the effects of a six-week balance training … · balance training protocol on chronic ankle...

THE EFFECTS OF A SIX-WEEK

BALANCE TRAINING PROTOCOL ON

CHRONIC ANKLE INSTABILITY A COMPARISON BETWEEN AN UNIAXIAL AND MULTIAXIAL

BALANCE BOARD

Mathias Declercq

Stijn Hermans

Supervisors: Prof. Dr. Roel de Ridder, Prof. Dr. Phillip Roosen

A dissertation submitted to Ghent University in partial fulfilment of the requirements for the degree of

Master in Rehabilitation Sciences and Physiotherapy

Academic year: 2016 - 2017

THE EFFECTS OF A SIX-WEEK

BALANCE TRAINING PROTOCOL ON

CHRONIC ANKLE INSTABILITY A COMPARISON BETWEEN AN UNIAXIAL AND A MULTIAXIAL

BALANCE BOARD

Mathias Declercq

Stijn Hermans

Supervisors: Prof. Dr. Roel de Ridder, Prof. Dr. Phillip Roosen

A dissertation submitted to Ghent University in partial fulfilment of the requirements for the degree of

Master in Rehabilitation Sciences and Physiotherapy

Academic year: 2016 - 2017

Expression of gratitude

The authors of this study would like to thank Prof Dr. P. Roosen (Promotor), Dr. R. De Ridder

(Co-promotor), without whom this thesis would not have been possible. We would also like

to express our gratitude to Thomas Rubens and Iman Amiri for helping with the study setup

and data collection. We would also like to thank our girlfriends, parents and friends for their

support during this thesis.

Special thanks goes out to all who participated in this study, and donated a significant

amount of their time to make this thesis possible.

Table of Contents List of figures and tables.......................................................................................................................... 7

List of abbreviations ................................................................................................................................ 8

1. Abstract (Nederlands) ..................................................................................................................... 9

2. Abstract (English) ........................................................................................................................... 10

3. Introduction ................................................................................................................................... 11

3.1. Lateral ankle sprain ............................................................................................................... 11

3.2. Chronic ankle instability ........................................................................................................ 12

3.3. Neuromuscular control ......................................................................................................... 13

3.4. Balance training ..................................................................................................................... 14

4. Methods ........................................................................................................................................ 15

4.1. Study design .......................................................................................................................... 15

4.2. Participants ............................................................................................................................ 15

4.3. Procedure and equipment .................................................................................................... 17

4.4. EMG ....................................................................................................................................... 17

4.4.1. Maximal voluntary contraction (MVC) .......................................................................... 17

4.4.2. Functional jumps ........................................................................................................... 18

4.5. Questionnaires ...................................................................................................................... 18

4.6. Intervention ........................................................................................................................... 19

4.7. Data analysis .......................................................................................................................... 20

4.7.1. MVC ............................................................................................................................... 20


4.7.3. Statistical analysis .......................................................................................................... 21

5. Results ........................................................................................................................................... 22

5.1. Baseline differences pre-intervention ................................................................................... 22

5.2. Intervention ........................................................................................................................... 23


5.2.2. MVC (mean) ................................................................................................................... 25

5.2.3. Subjective parameters ................................................................................................... 25

5.3. Baseline differences post-intervention ................................................................................. 27

6. Discussion ...................................................................................................................................... 27

6.1. Intervention effect ................................................................................................................ 27

6.2. Subjective parameters ........................................................................................................... 29

6.3. Strengths and limitation ........................................................................................................ 30

6.4. Practical implications and conclusion ................................................................................... 31

6.5. Acknowledgements ............................................................................................................... 32

7. References ..................................................................................................................................... 32

8. Abstract in lekentaal ...................................................................................................................... 36

9. Ethical approval ............................................................................................................................. 37

10. Appendix .................................................................................................................................... 39

10.1. Inclusion criteria questionnaire ......................................................................................... 39

10.2. CAIT questionnaire ............................................................................................................ 41

10.3. FADI questionnaire ............................................................................................................ 42

10.4. GROC questionnaire .......................................................................................................... 44

10.5. VAS questionnaire ............................................................................................................. 44

10.6. Varus-click test and anterior drawer test .......................................................................... 45

10.7. Relative muscle activation values: PL, PB and GaMed ...................................................... 46

10.8. Absolute muscle activation values: UNI-group ................................................................. 47

10.9. Absolute muscle activation: MULTI-group ........................................................................ 51

10.10. VAS-scores ......................................................................................................................... 54

10.11. Baseline differences post-intervention ............................................................................. 55

10.12. Linear Mixed Models: Fixed Effects ................................................................................... 56

List of figures and tables

Table 1: Included subjects

Table 2: Mean (SD) for demographic variables

Table 3: Standardized electrode placement

Table 4: Six-week balance training program

Table 5: Baseline differences pre-intervention

Table 6: Analysis functional jumps TA

Table 7: Analysis functional jumps GaMed

Table 8: Analysis MVC’s UNI group

Table 9: Analysis MVC’s MULTI-group

Table 10: Analysis subjective questionnaires

Table 11: GROC statistics

Picture 1: Forward Jump (FJ)

Picture 2: Side Jump (SJ)

Picture 3: Uniaxial wobble board

Picture 4: Multiaxial wobble board

Picture 5: GROC bar chart

List of abbreviations

CAI Chronic Ankle Instability

FAI Functional Ankle Instability

MAI Mechanical Ankle Instability

FJ Forward Jump

SJ Side Jump

MVC Maximal Voluntary Contraction

TA Tibialis Anterior

PL Peroneus Longus

PB Peroneus Brevis

GaMed Gastrocnemius, Medial Head

GaLat Gastrocnemius, Lateral Head

EMG Electromyography

UNI Uniaxial

MULTI Multiaxial

VAS Visual Analog Scale

GROC Global Rate Of Change

CAIT Cumberland Ankle Instability Tool

FADI Foot and Ankle Disability Index

LAS Lateral Ankle Sprain

SLS Single Leg Stance

RCT Randomized Controlled Trial

CI Confidence Interval

ROM Range Of Motion

CoP Centre of Pressure

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1. Abstract (Nederlands) Achtergrond: Chronische enkel instabiliteit (CAI) is een frequente lange termijn complicatie volgend

op een enkel inversie trauma. Mede door structurele weefselschade en/of neurale veranderingen

ervaren CAI patiënten vaak aan een verminderd evenwicht. Net daarom wordt heel vaak

balanstraining gebruikt in de revalidatie van CAI. Alleen zijn er nog grote lacunes in de literatuur welk

type balanstraining nu het meest effectief is in het kader van CAI revalidatie.

Doel: Het doel van deze studie is om de effecten na te gaan van een zes weken durende

balanstraining tussen twee groepen: een uniaxiale kantelplank en een multiaxiale oefentol.

Studievorm: gerandomiseerd gecontroleerd onderzoek (RCT)

Methode: 28 patiënten lijdend aan CAI (geselecteerd volgens inclusie criteria geformuleerd in het

Internation Ankle Consortium) voerden een voorwaartse en zijwaartse sprongoefening uit terwijl

spieractiviteit gemeten werd met oppervlakte EMG. Deelnemers werden willekeurig verdeeld in twee

even grote groepen: een UNI- en een MULTI-groep. Allen voerden ze hetzelfde trainingsschema uit

gedurende zes weken. Na het beëindigen van de balanstraining werden dezelfde sprongoefeningen

herhaald en spieractiviteit gemeten. Spieren die werden gebruikt voor analyse waren de TA, PB, PL,

GaLAT en GaMED. Om extra subjectieve data te verzamelen, vulden deelnemers bij beide

testmomenten enkele vragenlijsten in (CAIT, FADI, VAS-schalen en GROC).

Resultaten: Er werden geen baseline verschillen gevonden tussen beide groepen pre- en post-

interventie. Een algemene daling van de relatieve spieractivatie wordt gezien tijdens de

sprongoefeningen. In de UNI-groep zien we een significante daling van de TA en GaMed in beide

sprongvormen, dit zowel pre- als post-impact. Daarboven zien we een significant daling post-impact

van de PB bij de zijwaartse sprongen. In de MULTI-groep zien we een significante daling van de

GaMed post-impact bij de zijwaartse sprongen. In het algemeen zien we een stijging van de MVC

waarden na de interventie. Een duidelijke daling was zichtbaar in de VAS-scores, GROC-resultaten

tonen een duidelijke subjectieve verbetering na interventie in beide groepen.

Conclusie: Beterschap is merkbaar in beide groepen na de balanstraining, al is deze groter in de UNI-

groep. Relatieve spieractivatie is verminderd, wat verklaard kan worden door een toegenomen

spierkracht (MVC) door een beter gesynchroniseerde spiervezel contractie en/of door een

toegenomen stabiliteit. Deze verbetering wordt bevestigd door een combinatie van toegenomen CAIT

en FADI scores, lagere VAS scores en een positieve GROC. Echter, mede door het ontbreken van

baseline verschillen post-interventie tussen beide groepen, kan er geen eenduidige aanbeveling

gemaakt worden in verband met het meest gunstige type kantelplank.

Sleutelwoorden: chronische enkelinstabiliteit, balanstraining, electromyografie, uniaxiale

kantelplank, multiaxiale kantelplank.

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2. Abstract (English) Background: Chronic Ankle Instability (CAI) is a frequent long-term complication following lateral

ankle sprain. Because of structural tissue damage and/or neural changes in CAI subjects, an impaired

balance is frequently observed. Therefore, balance training is an acclaimed treatment method for CAI.

However, it is still unclear which type of balance exercises are best suited for an optimal treatment.

Goal: The purpose of this study was to compare the effects of a six-week balance training protocol on

muscle activity between two groups: a uniaxial and multiaxial balance board group.

Study design: Randomized controlled trial (RCT)

Methods: 28 patients with CAI (selected with inclusion criteria defined in the International Ankle

Consortium) performed a forward and sideways jumping task whilst researchers measured muscle

activity through surface-EMG. Included subjects were evenly randomized into two groups: a UNI- and

a MULTI-group. All subjects followed an identical balance training scheme for six weeks, with

respectively uniaxial and multiaxial balance boards. Upon conclusion of the training protocol, both

jumping tasks were repeated and also analyzed with surface-EMG. The muscles used for

measurement were TA, PB, PL, GaMed and GaLat. In order to obtain additional subjective parameter

data, subjects filled in some questionnaires on both test moments (CAIT, FADI, VAS-scales and GROC).

Results: No baseline differences were found between both groups pre- and post-intervention. In the

functional jumps, there is a general decrease in relative muscle activation. In the UNI-group, a

significant decrease in TA and GaMed is observed in both jumping tasks, this as well pre- as post-

impact. Additionally, a post-impact significant decrease is seen for the PB in the sideways jumps. In

the MULTI-group a significant decrease is seen in the GaMed in the post-impact time period in the

sideways jumps. In general, all MVC values were increased post-intervention. In the CAIT and FADI

questionnaires, a general increase in score was found post-intervention. In the VAS scores, a general

decrease was seen and GROC results are positive.

Conclusion: Post-intervention improvements are noticeable in both groups, although they appear to

be higher in the UNI-group. Relative muscle activation rates tend to decrease, which may be

explained by an increase in muscle force (MVC) because of a better synchronized muscle fiber

contraction and/or a better stability. Additionally, a combination of higher CAIT and FADI scores,

lower VAS scores and a positive GROC score confirm the subtle overall CAI improvements. However,

mainly because of the lack of post-intervention baseline differences, no clear recommendation can be

made concerning which type of balance board is more beneficial.

Keywords: chronic ankle instability, balance training, electromyography, uniaxial balance board,

multiaxial balance board.

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3. Introduction The goal of this study is to assess the differences in six-week balance training treatment effects

between an unidirectional and a multidirectional balance board. All subjects performed two different

jumping tasks (forward and sideways), whilst muscle force was measured through surface-EMG

analysis.

3.1. Lateral ankle sprain The foot and ankle-complex can be identified as the link between the human body and the ground.

Its function is crucial for completing daily life activities and is exposed to very high loads from time to

time. Hence ankle injuries are far from rare, with lateral ankle sprains being by far (77-85%) the most

prevailing ankle injury.(1, 2) This occurs when the foot is excessively inverted, hence a well-known

synonym for lateral ankle sprains are inversion traumata. Ankle injuries account for the largest

percentage of self-reported musculoskeletal injuries.(3) Researchers found a prevalence of 1 strain

per 10.000 active people daily in the United States.(4) Keeping in mind that as many as 55% of LAS

sufferers do not seek evaluation or treatment, it can be concluded that ankle sprains may be grossly

underreported.(5)

The symptoms experienced are irregular, often dependable upon the severity of the sprain. At first,

symptoms such as swelling, tenderness, pain and inability to sustain any weight can be observed.(6)

In proportion to the amount and kind of damaged structures around the ankle, more long term

symptoms can be diagnosed.

The pathomechanics of LAS are comparable in many situations: the rearfoot is forced into an

excessive supination. Research has shown that the position of the heel upon ground contact is

essential for the remaining duration of the stance phase. The more the centre of pressure (CoP) upon

heel strike is located laterally to the joint axis of the subtalar joint, the bigger the resulting inversion

moment is at the rearfoot. At a certain point, the inversion moment is too big for the muscles to

neutralize the movement, thus resulting in an ankle sprain. With these kinematic principles in mind,

it is important to acknowledge that wearing shoes can make an individual more vulnerable to LAS as

well. The shoe sole adds width to the foot, thus extending the possible hypersupination moment. The

friction between shoe sole and ground surface also adds a horizontal shear force component,

imposing more torque on the subtalar joint.(7)

An excessive supination in combination with an external rotation of the lower leg may result in a

strain of the lateral talocrural ligaments. Damage occurs when the forced strain exceeds the tensile

strength of the ligaments. The anterior talofibular ligament (ATFL) withstands less maximal load and

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energy compared to the posterior talofibular (PTFL) and calcaneofibular ligaments (CFL). Because of

this relative weakness, the ATFL is the first ligament to be damaged when the foot is sprained. When

this ligament is ruptured the internal rotation of the rearfoot increases and thus extra stresses the

intact lateral ligaments. This phenomenon is better known as “rotational instability”.(8) This allows

the CFL and the PTFL to be damaged as well.(9)

Many athletes are unwary that an ankle sprain can develop into a more severe, long term condition

called chronic ankle instability (CAI). Growing evidence confirms the relation between a cycle of ankle

sprain re-injury and joint synovitis, loose bodies, cartilage fibrillation and ultimately post-traumatic

osteoarthritis.(4)

3.2. Chronic ankle instability Chronic ankle instability or CAI is characterized by repetitive episodes of giving way or instability of

the ankle and/or the incidence of recurrent symptomatic ankle sprains.(10) Approximately 30-40 %

of acute lateral ankle sprains evolve to CAI, with some reporting percentages up to 70%.(10-12) The

observed posttraumatic changes are the main springboard for LAS evolving into CAI. These changes

can be categorized under functional and mechanical instability. It is believed that these two entities

work together in sustaining CAI.(11, 13)

Mechanical Ankle Instability (MAI) of the ankle complex occurs because of damage to structures

around the ankle joint after acute ankle sprain. The result is an ankle movement beyond the

physiologic limit of the ankle’s range of motion. MAI is often used synonymously with pathological

laxity of the ankle joint. One of the most common phrased causes for MAI is ligamentous damage.

Another possible insufficiency causing mechanical instability can be arthrokinematic impairments,

such as positional faults, hypomobility or hypermobility. The third cause of mechanical instability is

insufficiency caused by synovial and degenerative changes.(4)

Functional Ankle Instability (FAI) includes those deficits associated with ligamentous injury, mostly

proprioceptive, sensorimotor and neuromuscular. Because of those changes, the brain receives less

or false information about the position and muscle strength of the ankle. Thus, FAI results in a

deficiency of the dynamic defense mechanism protecting the rearfoot for hypersupination.(4) In

summary, FAI can be defined as the subjective feeling of ankle instability or recurrent, symptomatic

ankle sprains (or both) due to proprioceptive and neuromuscular deficits.(7) Whereas MAI is a range

of motion (ROM) beyond the physiological limits causing instability, FAI is defined is the instability

within the physiological ROM but beyond voluntary control.(14)

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3.3. Neuromuscular control It has to be clear that CAI can have far-reaching consequences for one’s daily life activities. As

suggested above, maintaining the foot’s stability during gait and other functional activities is crucial.

Accurate sensorimotor control is therefore vital, a concept comprehending neuromuscular control,

proprioception, postural control and strength.(1) This article focusses on neuromuscular control, a

phenomenon that can be described as a subconscious activation of dynamic control addressed in

preparation for, and in response to, joint motion and loading.(15) For this ability to work properly, a

constant interaction between afferent input and efferent output of the central nervous system is

necessary. It has been proven that impaired neuromuscular control is a risk factor for ankle injury in

previously uninjured football players.(14)

One of the main sources for afferent information are the mechanoreceptors found in ligamentous

and capsular tissue. These receptors are often damaged after LAS, resulting in deafferentiation.(16,

17) Sensory deficits may also be present, caused by joint inflammation and pain. Joint laxity may

induce a diminished ability to detect joint motion and position.

Efferent output may be affected as well, caused by changes in central processing and alpha

motoneuron pool excitability.(18) It has been proven that excitability is altered in muscles crossing

the ankle joint but also in proximal leg muscles in people suffering from CAI.(19, 20) In addition,

bilateral postural control deficits have been observed in patients suffering from acute ankle sprain

and CAI. (11) Due to these findings there is obvious evidence of central neural changes.

Neuromuscular control itself can further be divided into a feedforward and a feedback loop. Both are

equally important in maintaining dynamic balance. The easiest way to define both loops is by stating

that the feedforward loop is responsible for preparing our body for a certain action and that the

feedback loop is the reaction of our body to that action. The majority of the literature about

neuromuscular control is focusses on the feedback loop, only a minor part concentrates on the

feedforward loop. A possible explanation for this difference could be that investigating the feedback

loop is less complicated. Various theories suggest that a wide spectrum of feedforward and feedback

mechanisms may contribute to neuromuscular control deficits in CAI.(11, 21, 22)

Feedforward neuromuscular control can be divided in two facets. The first facet, planning

movements based on sensory information from past experiences, is impossible to measure. The

second facet, preparatory muscle activity, is measurable through EMG-measurement. This

preparatory activity, in advance of an anticipated impact, is essential for accurately positioning the

limb and inducing a dynamic joint stiffness upon landing. It also leads to an improved stretch

sensibility and hence a faster muscle reaction time upon landing.

Feedback neuromuscular control is essential in constantly adjusting muscle activity via reflex

pathways. Therefore, this type of muscle activity is often called reactive. This reflex mediated

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dynamic stability is related to speed and magnitude of the perturbation. Crucial for this loop is a

proper interaction of afferent and efferent output. Various injuries lead to a decrease in

neuromuscular control, as for CAI a proven setback in neuromuscular feedback has been found.(4,

11, 20-22)

For example, CAI-sufferers exhibit a delayed peroneal muscle reflex compared to healthy subjects,

which is essential in preventing the ankle to move to a hypersupination. These could be attributed to

proprioceptive deficits and/or to spinal level motoneuron alterations.(11, 23) Important is, however,

that this reflex is too slow to prevent hypersupination in healthy subjects as well. As written

previously, an inappropriate positioning of the lower limb before heel strike increases the potential

for injury. Because once the foot reaches the ground, the line of the reaction force is already

determined. If the foot is held in an inverted position when it reaches the ground, an external-

inversion load is placed upon the joint, increasing the likelihood of injury.(7, 24) It is clear that an

adequate position of the rearfoot upon ground contact is crucial, which can only be obtained through

appropriate feedforward neuromuscular control. Further research is needed to elucidate this matter.

3.4. Balance training Various rehabilitation protocols are used for CAI, typically they mainly involve exercises for

enhancing balance and proprioception. Balance training is one of the well-known protocols,

commonly used in CAI. Maintaining balance requires adequate integration of afferent visual,

vestibular and somatosensory inputs to generate an adequate efferent neuromuscular response.(25)

Lower limb injuries, such as ankle sprains, are believed to affect balance capabilities.(26) Because of

the initial injury mechanoreceptors may be damaged, hence leading to a (partial) deafferentation

and in its turn to alterations in muscle spindle sensitivity.(16, 27) These changes might lead to an

impaired balance and functional ankle instability. With balance training, muscle activity levels of

ankle stabilizing muscles are maximally stimulated and this could lead to a normalised neuromuscular

control. There is evidence of an improved postural control because of balance training, hence

implying a curative and a preventive effect.(16, 28, 29) A therapeutic effect has been shown in

subjects who suffered a previous ankle sprain.(18, 30) Furthermore, a preventive effect has been

found as well, as balance training could help prevent lateral ankle sprains.(31, 32) An explanation, as

stated by Asthon-Miller et Al. (2001) could be a higher stimulation of muscle spindles caused by long-

term balance training. This increased stimulation would improve neuromuscular control and thus a

better functional ankle stability.(33)

Until this day, there is no consensus about which type and modalities of balance training are best for

optimal rehabilitation.(18) The higher the muscle activity during balance training, the quicker the

rehabilitation speed and thus the quicker the return to performance.(34) The magnitude of the

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muscle activity however, depends of the stability of the used device.(35) Therefore two different

balance boards are selected for this article: a uniaxial and a multiaxial type. As already well-known,

the peroneus longus muscle is vital in counteracting the sudden inversion moment at the ankle.(23,

36-41) In the uniaxial balance board, previous research conducted by De Ridder et Al. (2014), has

shown that the biggest peroneus longus activity is present when the balance board axis is aligned

with the frontal plane.(36) For the multiaxial balance board, which has 360 degrees of freedom and

thus less rotational stability, a more generalised muscle activity would be apparent.

The purpose of this study was primarily comparing the effects on muscle activation levels of four

stabilizing ankle muscles, comparing the effects of a six-week balance training protocol on a uniaxial

and on a multiaxial balance board. Two functional jumping activities were used for analysis pre- and

post-intervention. The hypothesis put forward is that the uniaxial group (UNI-), would have a better

trained peroneus longus muscle (as they solemnly train inversion and eversion) compared to the

multiaxial group (MULTI-). And secondly, that the MULTI-group would exhibit a more general training

effect on all measured ankle muscles.

4. Methods

4.1. Study design Randomised controlled trial.

4.2. Participants Subject recruitment was mainly undertaken by e-mailing all UGent physiotherapy students a

questionnaire containing various questions concerning their ankles in light of Gribble’s Position

Statement.(42) Supplementary, multiple advertisements were placed on social media and in various

sport clubs. Inclusion criteria were based on the International Ankle Consortium’s statement. (41)

These criteria suggest that CAI can be defined by: (1) a history of at least one significant ankle sprain,

(2) a history of the previously injured ankle joint giving way, and/or recurrent sprain and/or ‘feelings

of instability’, and (3) a general self-reported foot and ankle function questionnaire. A base level of

sportive activities were also required. Key exclusive criteria were: ligamentous lesions, surgery and

no feeling of instability or giving way. A second questionnaire, the Cumberland Ankle Instability Tool

(CAIT), was sent if criteria were met. (43) Only subjects scoring 24/30 or less were eligible. The ethics

committee of the University of Ghent granted ethical approval, and a written informed consent was

obtained for every patient who enrolled in our study.

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After the screening, 33 subjects were included in this study, of which 4 subjects dropped out after

the pre-intervention screening. One more subject was lost to follow-up after the intervention,

leaving us with 28 subjects evenly divided over the two groups. (Table 1)

Table 1: Included subjects

All patients were randomised into two groups by an online tool. One group performed the balance

training protocol with the uniaxial wobble board (UNI), the other group did the protocol with a

multiaxial wobble board (MULTI). (Table 2)

Uniaxial Multiaxial Total P-value

Gender 4♂/10♀ 1♂/13♀ 5♂/23♀ P=0.139

Age

Mean (SD)

20.86

(3.718)

21.07

(2.269)

20.96

(3.024) P=0.258

Length (cm)

Mean (SD)

171.36

(8.500)

168.93

(9.482)

170.14

(8.922) P=0.263

Weight (kg)

Mean (SD)

66.3429

(7.51334)

65.6643

(8.19565)

66.0036

(7.7226) P=0.970

Table 2: Mean (SD) for demographic variables.

No significant baseline differences were found: gender (P=0.139), age (P=0.258), length (P=0.263)

and weight (P=0.970). Statistical analysis was performed with a Chi-Square test.

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4.3. Procedure and equipment All tests were conducted in the week immediately before and after conclusion of the six-week

balance training program. Standardized shoes were used throughout the jumping trials, except for

two subjects whose shoe size were not available. Possible mechanical instability was objectified with

the varus click test and the anterior drawer test.

4.4. EMG Five stabilising ankle joint muscles were analysed with surface EMG (sEMG) (Noraxon TeleMyo): the

tibialis anterior (TA), peroneus longus (PL), peroneus brevis (PB), medial head of the gastrocnemius

(GaMed) and lateral head of the gastrocnemius (GaLat). A telemetric TeleMyo EMG system was used

for measurement (Noraxon U.S.A. Inc, Scottsdale, Arizona 85260, USA). Subjects’ skin was prepared

before electrode application: skin shaving, scrubbing and cleansing with ethanol. Bipolar Ag/AgCl

surface electrodes, 2cm diameter, with conducting gel were placed with an inter-electrode distance

of 2 cm center-to-center and parallel to the muscle fibres according to surface ElectroMyoGraphy for

Non-Invasive Assessment of Muscles (SENIAM) guidelines (www.seniam.org). Muscle motor points

(and hence electrode localisation) were located in a standardized manner (Table 3). All preparations

were carried out by the same researcher to diminish variability.

Table 3: Standardized electrode placement. (2 electrodes/muscle)

4.4.1. Maximal voluntary contraction (MVC) In order to normalize data measured during the jumping activities, a mean MVC was required of

every muscle. All muscles were tested in a standardized, isometric manner. The PL, PB and TA

muscles were tested in a sitting position. A manual resistance towards pronation was given for the PL

and PB muscle, whereas a manual resistance towards dorsiflexion was required for the TA. The

gastrocnemius was tested in a supine position, where the subjects were asked to perform an

isometric plantarflexion, pushing against a wall. For every muscle, 3 different isometric contractions

lasting for 5 seconds each, were required. A marker was placed on the subjective moment of

reaching maximal force. Every assessment of the MVC was made by the same researcher.

Muscle electrode placement

TA 1/3th of the distance between fibula head and medial malleolus (from proximal)

PM 1/4th of the distance between fibula head and lateral malleolus (from proximal)

PL 1/4th of the distance between fibula head and lateral malleolus (from distal)

GaMed Most prominent bulge of the muscle

GaLat Most prominent bulge of the muscle

Reference electrode

Bony fibula head

http://www.seniam.org/

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4.4.2. Functional jumps Subsequently subjects were asked to perform 5 valid forward (FJ) and sideways jumps (SJ). In order

to measure landing forces, a force plate (AMTI, Watertown, Massachusetts 02472, USA) measuring at

200Hz was embedded in a walkway. The required jumping distance was calculated individually for

every subject, based upon their body length (FJ = 40% height / SJ = 33% height). A landing zone was

visually marked on the force plate and a 15cm high hurdle was placed halfway, for standardisation of

jump height and distance. An attempt was valid if the subject took off on both legs simultaneously

and landed on their affected side. Upon landing, they had to keep their balance for 5 seconds with

their hands akimbo. Two test trials for each jumping variation were awarded.

Picture 1: Forward Jump (FJ)

Picture 2: Side Jump (SJ)

4.5. Questionnaires Upon initial and final assessment, subjects were requested to fill in some questionnaires. Among

them were a general survey inquiring for their medical history, a CAIT, a Foot and Ankle Disability

Index (FADI) and a series of Visual Analog Scale (VAS) styled questions concerning the jumping

activity. The CAIT questionnaire objectifies ankle instability, subjects had to select a box with the

answer best suited for them in every question, for both feet. A score of <24/30 could be interpreted

as ankle instability.(43) The FADI is divided into two subcategories: a first section focussing on daily

life (FADI A) and a second part highlighting solemnly sportive activities (FADI B). Respectively a score

is awarded on /104 and /32, which are then expressed as percentage scores. For every jumping

activity, 4 questions were proposed to every subject with a VAS-styled answering method. Questions

targeted pain, fatigue, instability and difficulty experienced during and after conclusion the jumps.

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Subjects’ marks on the 10cm line were measured and noted as a score on /100. A Global Rating Of

Change scale (GROC) was added for the final assessment. The GROC scale is used to measure

subjective improvement (of a certain intervention). A value, corresponding with a certain feeling, is

ticked-off.(Appendix 1-5) Statistic analysis was performed with a paired student’s T-test.

4.6. Intervention The intervention consisted of a 6 week stability training program.(44) Subjects were randomly

divided (using a computer programme) in two groups, both containing 14 subjects. One group

assisted the training with a uniaxial wobble board whilst another group used a multiaxial equivalent.

The axis of the uniaxial wobble board was aligned with the frontal plane, therefore the only possible

movements were pronation and supination. The radius of both wobble board curvatures are

identical: 21cm in width and 6.8cm in height with a diameter of 23cm.

Each subject was urged to perform three trainings a week. Every training session was supervised by

either one of the four researchers, this to ensure maximal quality of the training. Every week, the

training difficulty increased. Single leg stance (SLS) on the affected leg was used as a base exercise. In

between trials a 30” resting period was granted, a 2’ break was given in between exercises. A

summary of the training program is displayed in table 4.

Table 4: A six-week balance training program

Week 1 modalities Eyes Remarks

SLS 3x 20” open Hands on the waist, looking forward


Week 2



Week 3

SLS 3x30” open Hands on the waist, looking forward

SLS 3x30” closed Hands are free

SLS + reach 3x2 in every direction open Hands on the waist, reach = 30cm

Week 4


SLS 3x30” closed Hands on the waist, looking forward


Week 5




SLSquat 3x20” open Hands on the waist, looking forward

Week 6




SLSquat 3x20” open Hands on the waist, looking forward

20

Because of the difficulty of the SLS, especially for the multiaxial wobble board group, subjects were

allowed to sum up all their combined time balancing on the wobble board to attain their total time

target. For the SLS + reach exercises, the patients had to reach to 4 cones with the non-affected foot

whilst balancing on their affected leg. Cones were arranged in 4 directions: front, left, behind, right.

Distance to the cones was calculated to the centre of the wobble board axis.

Picture 3: uniaxial wobble board

Picture 4: multiaxial wobble board

4.7. Data analysis All EMG data was analysed with Myoresearch 3.4.5. Master edition (Noraxon U.S.A. Inc, Scottsdale,

Arizona 85260, USA).

4.7.1. MVC All raw MVC data was rectified and smoothed (RMS 50ms). Within every trial a 3-second interval

following the manually placed marker was demarcated. Mean values were calculated for every

interval. Subsequently the mean of all three interval means was calculated and used for further

analysis. This was done for both pre- and post-intervention MVC data.

21

4.7.2. Functional jumps This raw data was rectified and smoothed (RMS 50ms) as well. EMG data was paired with the

pressure plate data. For identifying moment of impact a marker was placed on the first pressure

plate value greater than 15N. Around this threshold, a 200ms interval before and after contact was

demarcated for every jump. Mean EMG values of all five muscles in those time periods were noted.

Again, a mean value of those means was calculated for further analysis. In this manner EMG mean

values were obtained for both time periods in both jumping activities. This was done for both pre-

and post-intervention functional jumping data.

For attaining a normalisation of the acquired functional jumping data, these mean recorded voltages

were divided by the mean MVC values. As a result, the jumping data are expressed as a percentage

of the subjects’ ‘maximal force’.

These percentages were used for statistical analysis. Twelve outliers were discarded for analysis.

4.7.3. Statistical analysis Statistical analysis was performed with SPSS 24 (SPSS Inc., Chicago, Illinois, USA). After pairing the

pre- and post-intervention data, a Linear Mixed Model analysis was applied to the newly paired data.

Analysis focussed on time, intervention and a nested term combining both. Consequently we

received information about baseline differences and interaction effects. Interaction effects were

defined for intervention duration, balance board group and a combination of both. Because of the

5% chance of reporting a type I error using Linear Mixed Models, the standard significance level of p

< 0.05 was divided by the amount of used muscles in our analysis (4), generating a significance level

of p < 0.012. MVC’s were also compared to one each other, this was done through a paired samples

T-test.

22

5. Results

5.1. Baseline differences pre-intervention No significant differences between the two study groups were found for age, weight, length and

mechanical instability (Table 2).

Of the 28 subjects, 5 subjects experienced a positive anterior drawer test (UNI 4 / MULTI 1) whereas

9 subjects perceived a positive varus click test (UNI 5 / MULTI 4). (Appendix 6)

Evenly important, no significant baseline differences were observed for muscle activities during both

FJ and SJ. (Table 5)

Pre- intervention

Time period UNI

Mean (SD) MULTI

Mean (SD) Mean difference

(95% CI) Sign.

(P<0.012)

TA

FJ before contact

42.794 (7.436)

35.548 (7.436)

7.246 (-14.107 , 28.598)

0.495

FJ post contact

116.217 (12.644)

102.116 (12.644)

14.101 (-21.990 , 50.193)

0.435

SJ before contact

49.273 (10.808)

36.914 (10.808)

12.359 (-18.659 , 43.378)

0.424

SJ post contact

150.953 (21.462)

122.129 (21.462)

28.824 (-32.348 , 89.997)

0.347

PL

FJ before contact

141.745 (20.808)

94.903 (21.541)

46.842 (-13.367 , 107.051)

0.124

FJ post contact

247.083 (45.903)

136.520 (47.519)

110.563 (-22.257 , 243.382)

0.101

SJ before contact

131.965 (17.619)

90.758 (18.186)

41.207 (-9.781 , 92.195)

0.111

SJ post contact

222.072 (37.543)

127.930 (38.928)

94.142 (-14.481 , 202.764)

0.088

PB

FJ before contact

120.504 (19.647)

106.331 (19.647)

14.173 (-41.625 , 69.971)

0.612

FJ post contact

153.220 (19.032)

122.668 (19.032)

30.552 (-23.546 , 84.649)

0.262

SJ before contact

103.844 (13.986)

107.227 (13.986)

-3.382 (-43.109 , 36.344)

0.865

SJ post contact

152.144 (16.628)

128.110 (16.628)

24.034 (-23.244 , 71.312)

0.312

23

Table 5: Baseline differences pre-intervention

5.2. Intervention

5.2.1. Functional jumps Within FJ before contact in the UNI-group, a significant lower muscle activation was only found for

the TA (p=0.007) and GaMed (p=0.002) muscles post-intervention. In the MULTI-group, no significant

differences were found for the same interval. A general decline in muscle activity post-intervention

was observed in both groups for this time period. The decline, however, was bigger in the UNI-group

for all muscles except GaLat.

In the SJ exercise, a significant decrease is noted in the UNI-group, again for both the TA (P=0.008)

and GaMed (P=0.008) muscles. All muscles in both groups exhibit a general reduction in post-

intervention muscle activity, the overall drop is greater for the UNI-group in all muscles except PB

and GaLat.

Post-impact in the FJ activity we notice a significant decrease in EMG activation post-intervention for

both TA (P=0.000) and GaMed (P=0.001) muscles in the UNI-group, and in the GaMed (P=0.002)

muscle for the MULTI-group. The other muscles showed a lower activation, but these differences

were not significant. Overall decrease is greater for the UNI-group in all muscles.

For the last observation, we focus on the post-impact SJ exercise. Here a significant lower activation

of the TA (P=0.003), PB (P=0.004) and GaMed (P=0.008) muscles in the UNI-group are noted. For the

MULTI-group a significant decrease is only seen in the GaMed (P=0.004) muscle.

Muscles without significant interventional changes (PL, PB and GaLat) can be found in appendix 7.

GaMed

FJ before contact

188.072 (18.857)

213.441 (18.857)

-25.369 (-78.947 , 28.208)

0.346

FJ post contact

134.596 (17.634)

148.255 (17.634)

-13.660 (-64.064 , 36.745)

0.587

SJ before contact

164.428 (16.402)

181.058 (16.402)

-16.631 (-63.366 , 30.105)

0.477

SJ post contact

134.369 (16.412)

149.651 (16.412)

-15.282 (-62.250 , 31.686)

0.514

GaLat

FJ before contact

265.379 (45.754)

269.272 (45.754)

-3.893 (-133.796 , 126.010)

0.952

FJ post contact

231.410 (41.490)

200.800 (41.490)

30.610 (-87.325 , 148.545)

0.604

SJ before contact

212.507 (45.632)

222.577 (45.632)

-10.070 (-139.715 , 119.575)

0.877

SJ post contact

233.259 (47.408)

219.955 (47.408)

13.304 (-121.623 , 148.231)

0.844

24

Absolute EMG values (voltage levels before dividing them with MVC values) were compared as well.

Very little mean differences pre- and post-intervention were found. In the UNI group, two significant

decreases were found: the TA after contact in both FJ and SJ. In the MULTI-group, an increase in

most values was found. However, these results were not significant. (Appendix 8, 9)

Tibialis Anterior

Mean (SE) Pre Intervention

Mean (SE) Post Intervention

Mean difference (95% CI)

Sign. (P<0.012)

UNI Before Impact

FJ 42.794 (7.436)

26.034 (7.436)

16.760 0.007*

SJ 49.273 (10.808)

24.839 (10.808)

24.435 0.008*

After Impact

FJ 116.217 (12.644)

60.820 (12.644)

55.397 0.000*

SJ 150.953 (21.462)

76.101 (21.462)

74.852 0.003*

MULTI Before Impact

FJ 35.548 (7.436)

24.037 (7.436)

11.512 0.055

SJ 36.914 (10.808)

25.281 (10.808)

11.633 0.187

After Impact

FJ 102.116 (12.644)

77.108 (12.644)

25.008 0.060

SJ 122.129 (21.462)

93.435 (21.462)

28.694 0.222

Table 6: analysis functional jumps TA

Gastrocnemius Medialis

Mean (SD) Pre Intervention

Mean (SD) Post Intervention


Sign. (P<0.012)

UNI Before Impact

FJ 188.072 (18.857)

106.610 (18.857)

81.462 0.002*

SJ 164.428 (16.402)

111.972 (16.402)

52.456 0.008*

After Impact

FJ 134.596 (17.634)

71.953 (17.634)

62.643 0.001*

SJ 134.369 (16.412)

90.712 (16.412)

43.657 0.008*

MULTI Before Impact

FJ 213.441 (18.857)

154.777 (19.547)

58.664 0.025

SJ 181.058 (16.402)

132.275 (16.934)

48.784 0.016

After Impact

FJ 148.255 (17.634)

88.264 (18.107)

59.992 0.002*

SJ 149.651 (16.412)

100.719 (16.831)

48.932 0.004*

Table 7: analysis functional jumps GaMed

25

5.2.2. MVC (mean) Subsequent results, found in table 7 and 8 were found using a paired samples T-test. In general, we

observe an elevation in post-intervention mean MVC-values. However, the raise is only significant for

the GaLat in the UNI-group (P=0.000). For the MULTI-group, on the other hand, significant increases

are seen in TA (P=0.000), PB (P=0.000), GaMed (P=0.001) and GaLat (P=0.000) muscles’ mean MVC.

Table 8: analysis MVC’s UNI group

Table 9: analysis MVC’s MULTI-group

5.2.3. Subjective parameters

5.2.3.1. CAIT

In both groups a raise in post-intervention scores are observed, the UNI-group improves 4.14%

(significant, P=0.016) whereas the MULTI-group improves 2.71% (not significant, P=0.876). (Table 10)

5.2.3.2. FADI

An overall raise in post-intervention scores are observed, the only significant raise however is seen in

the UNI-group for the A part (P=0.001). Other results are slightly better but not significant. (Table 10)

UNI Pre-intervention

Mean (SD) Post-intervention


(95% CI) Sign. (2-tailed)

(P<0.05)

TA 383.27

(241.10) 466.17

(112.08) -82.9

(-157.15 , -8.65) 0.030*

PL 227.58

(148.51) 261.31

(164.28) -33.73

(-69.89 , 2.42) 0.066

PB 275.39

(248.47) 356.48

(151.53) -81.09

(-145.85 , -16.33) 0.016*

GaMed 322.84

(306.84) 412.24

(259.51) -89.40

(-185.33 , 6.52) 0.066

GaLat 192.35

(175.98) 313.51

(185.02) -121.16

(-165.60 , -76.71) 0.000*

MULTI Pre-intervention



(95% CI) Sign.

(P<0.05)

TA 335.78

(128.97) 423.26

(136.11) -87.48

(-131.64 , -43.32) 0.000*

PL 253.23

(124.93) 274.47 (95.30)

-21.24 (-68.43 , 25.95)

0.364

PB 233.61 (87.25)

367.62 (103.15)

-134.00 (-168.60 , -99.41)

0.000*

GaMed 181.20 (73.63)

324.69 (207.72)

-143.49 (-219.95 , -67.02)

0.001*

GaLat 116.44 (60.03)

293.63 (191.25)

-177.20 (-256.00 , -98.39)

0.000*

26

Table 10: Analysis subjective questionnaires

5.2.3.3. VAS

Overall a clear decrease in post-intervention values is observed. The only significant result, however,

is a decrease in pain reported during SJ within the UNI-group (p=0.017). All other decreases are not

significant for any group or any jump. (Appendix 10)

5.2.3.4. GROC

The mean value of the MULTI-group (group B) is slightly higher: 4.36 compared to 4.29 for the UNI-

group (group A), but the difference is not significant (P=0.895). (Picture 5) (Table 11)

Picture 5: GROC bar chart (UNI = blue, MULTI = green)

N Mean Std. Deviation Std. Error Mean

UNI 14 4.29 1.069 .286

MULTI 14 4.36 1.692 .452

Table 11: GROC statistics

Pre-intervention


Mean (SD) Mean Difference

(95% CI) Sign.

(P<0.05)

UNI

CAIT 15.21

(4.080) 19.36

(4.568) -4.143

(-6.313, -1.972) 0.016*

FADI A 88.324 (8.270)

93.201 (7.978)

-4.876 (-7.921, -1.832)

0.001*

FADI B 73.438

(12.119) 84.375

(12.856) -10.938

(-18.041, -3.834) 0.059

MULTI

CAIT 17.07

(3.222) 19.79

(5.102) -2.714

(-6.269, 0.841) 0.876

FADI A 92.239 (6.928)

93.887 (5.328)

-1.648 (-6.466, 3.169)

0.755

FADI B 75.893

(15.379) 84.152

(11.786) -8.259

(-16.285, -0.233) 0.067

27

5.3. Baseline differences post-intervention There are no significant baseline differences post-intervention. Only the GaMed muscle in the FJ

before contact nears the significance level of p < 0.012. All other muscles are remotely off

significance. (Appendix 11)

6. Discussion The main objective of this study was to compare a six-week balance training programme performed

on a uniaxial or a multiaxial balance board in subjects (N=28) with chronic ankle instability. To

objectively compare both groups, we analysed EMG data of 4 crucial muscles to ankle stability (TA,

PL, PB, GaLat and GaMed) during forward and sideways jumping tasks, this pre- and post-

intervention. A 200ms period pre- and post-landing was identified. Obtained EMG-data was divided

by associated mean MVC values as a manner of normalization. The subjects were asked to fill in a

collection of questionnaires pre- and post-intervention for accurate descriptive statistical analysis.

6.1. Intervention effect The hypothesis of this study was seeing an increased PL activity in the UNI group (because their

training was focused solemnly on inversion and eversion) and a more generalized increase in ankle

stabilising muscle activity in the MULTI-group (as they train in all 360°). Rather than noticing an

increase in muscle activity, an overall decrease for the normalized data was noted. Within the UNI-

group, the downfall was significant for the TA and GaMed in all 4 time periods and for the PB in the

SJ post-impact. In the MULTI-group, significant decreases were apparent for the GaMed in all time

periods.

The mean overall descent is bigger in the UNI-group, with percentages up to 83% less muscle activity

post-intervention. Comparing mean normalized overall muscle activity, decreases tend to be larger in

the FJ (23.73%) than in the SJ (16.93%) and larger post-impact (32.13%) than pre-impact (8.53%).

In search of an explanation for these curious findings, researchers investigated the two components

forming the normalized data as well. When comparing the absolute EMG values pre- and post-

intervention, little differences are discernible. (Appendix 8,9) Within the UNI-group, changes are

subtle as the number of gains and losses in post-intervention mean voltages even each other out.

Two changes are significant: TA muscle activity decreases after contact in both jumping varieties.

Regarding the MULTI-group, a different story is noticeable: in 16 of the 20 defined intervals, the

mean voltage increases. None of these raises, however, are significant.

Inspecting the mean MVC values pre- and post-intervention, an overall increase in activation was

found. In the UNI-group TA, PB and GaLat increase significantly. Equivalent results are apparent for

28

the MULTI-group, with an additional significant increment for the GaMed. The overall gains are larger

for the MULTI-group: 112,64%, this is 31.02% more than the overall gains within the UNI-group.

These results seems to be consistent, hence alluding an increase in the maximal activation rate of the

muscle fibres. Previous studies have found that the axis of the balance board has influence on which

muscles are activated, this can explain the difference between the UNI- and the MULTI-group.(36)

Other research has found evidence of an increase in Hmax/Mmax ratio because of a balance training

protocol.(45) This ratio, describing the maximal H-reflex to maximal M-wave, is a measure of

effectivity of α-motoneuron activation. The better the ratio, the larger relative amount of α-

motoneurons activated by afferent nerve fibres.(45) This could be an explanation for the increase

observed in the MVC’s, since an increase in α-motoneuron activation indicates a greater amount and

a better synchronized muscle fibre activation.(46-48) A six-week training programme is insufficient

for generating a significant muscle hypertrophy, literature has proven that force gains in the first

weeks of training are to be found in central/peripheral neural changes.(49-51) Important

acknowledgment, however, is that this improved Hmax/Mmax ratio was observed in CAI subjects

performing a double-limb stance balance training protocol.(45) Seemingly contradictory, the same

study found a higher presynaptic reflex depression in single-limb stance after balance training in CAI

subjects compared to healthy controls. Presynaptic inhibition is believed to be a short-term response

to injury. A better ability to modulate the size of the reflex can lead to a better balance, as a

dampening of an exaggerated response to perturbation can increase stability. The double-limb

stance, where the Hmax/Mmax ratio changes were found, is an intrinsically more stable position

than the single-limb stance. This may explain why, in this position, there were no changes in

presynaptic reflexes as this position may not need a modulation in presynaptic reflex.(45) These

findings could explain why the MVC’s increase post-intervention. Still, a difference of 31.02% in mean

overall MVC exists between both groups, favouring the MULTI-group. A possible explanation could

be that the MULTI-group trains in a wide variety of degrees, therefore this could result in a bigger

activation of the ankle musculature.(34) Another possible contributing factor is the vast amount of

effort MULTI-group subjects experienced to stay atop their balance boards. They were constantly

challenged in maintaining balance, whilst the UNI-group mastered the exercises relatively fast. The

constant challenge may have extra stimulated α-motoneurons, hence the greater MVC increase.

As previously stated, the normalized data is acquired by dividing the absolute EMG data with the

MVC data. With a significant increase in MVC values (the denominator) and little change in the raw

EMG values (the nominator), the result is a lesser relative muscle activation rate post-intervention.

This can mean that muscle strength is improved because of a better muscle fibre activation

coordination and/or that less effort is needed in maintaining balance. Some studies indeed suggest

that a training protocol can cause changes in the neuromuscular system and the rate of force

29

development (this is a quality needed for active stabilisation of the joints).(52-56) Other, previously

conducted studies combining kinematics and EMG analysis, observe a lower activation of the TA, PL

and GaMed in CAI patients due to altered kinematic positions and reductions in joint

movements.(57) We can however not conclude if the kinematics were changed, because we did not

use this as an outcome parameter.

Also apparent in the performed Linear Mixed Model analysis is that for some muscles a significant

effect of intervention duration is found. (Appendix 12) On the other hand, no significant interaction

effects of intervention duration and balance board type are discernible. This means that some

muscles significantly improve because of a six-week balance training protocol that has been fulfilled,

but what group subjects were assigned to has no clear effect on muscle activity. This finding can be

extended to the baseline differences: pre-intervention no significant differences are observable.

Neither are significant differences post-intervention found, although there are some significant

differences in relative muscle activation rate during the jumping tasks post-intervention. This means

that, despite the slight advantage of the uniaxial balance board, the benefits appear to be too little to

impose a post-interventional change. Supposedly, a collaboration of various causes would be the

reason for these small benefits. It may be possible that the six-week training period is too short to

impose a transfer from the relatively static balance training program to the more dynamic jumping

tasks used as evaluation method, resulting in subtle changes during the post-interventional jumping

tasks.

6.2. Subjective parameters Researchers’ hypothesis is that there would be an overall improvement in subjective parameter

outcome post-intervention. The CAIT and FADI questionnaires are often used in balance training

protocols and have proven their clinical relevance. (4, 58-60) Overall, obvious improvements are

apparent in both groups, alluding that balance training could augment a subjectively reported degree

of functionality. Increments tend to be higher in the UNI-group, in comparison with the MULTI-group

differences of 1.4% (CAIT), 3.3% (FADI A) and 2.6% (FADI B) can be calculated, all favoring the UNI-

group. Significant increases can be found in CAIT and FADI A scores for the UNI-group. The pre-

intervention scores, however, are lower in the UNI-group, thus explaining their significant

differences.

Researchers identified an overall decrease in VAS scores, concerning all 4 questions. One difference

appears to be significant: SJ pain in the UNI-group. A possible explanation for the few significant

differences could be the high standard deviation in the means pre- and post-intervention. (Appendix

10) Nevertheless there are obvious decreases in all subjects’ VAS-scales, but some subjects who

started with a very high VAS score stayed relatively high, and the other way around. The biggest

30

decreases are observed for the questions about difficulty and instability, in the researchers’ opinion

these are the most important questions in this VAS-scale. In the UNI-group there is a post-

intervention overall mean decrease of 17.6mm in the FJ and 22.47mm in the SJ. The mean decrease

within the MULTI-group is 18.97mm FJ and 13.14mm SJ. Therefore, the differences in overall means

imply a minor favour towards the MULTI-group for FJ (1.37mm) and a favour towards the UNI-group

for SJ (9.33mm).

In the GROC questionnaire, rating subjective changes caused by an intervention, an overall

improvement is seen as well. The improvement in both groups is about the same, UNI-group

rapports a 4.29/7 mean score whilst the MULTI-group scores slightly better with a 4.36/7 mean.

Nevertheless, the dispersion within the MULTI-group is larger: one subject scored 0/7, another one

scored 1/7. This means those subjects feel no or only little improvement. Whereas in the UNI-group,

all subjects scored 3/7 or higher, meaning that they all feel at least somewhat better. In conclusion, it

can be said that all but one subject felt better-off afterwards the balance training protocol.

In general, both groups subjectively report a better feel concerning their ankle and it’s functioning.

As in most findings, the improvement appears to be more profound for the UNI-group. A possible

explanation could be that the MULTI-group suffered much more effort when doing the training

program, whereas the UNI-group quickly became familiar with their balance board. Hence, UNI-

group subjects may experience a bigger improvement since they had less effort maintaining balance.

As the MULTI-group kept struggling, those subjects could feel subjectively less trained.

6.3. Strengths and limitation

A first strength is that we were almost certain that subjects who participated in this study suffered

from CAI, because of the strong inclusion criteria.(42) A noticeable drawback of these criteria is that

they led to a small study sample. For future research, larger populations are desirable.

The fact that, on every training occasion, at least one researcher was present for piloting the subjects

is another strength. Some other studies give their subjects a home exercising program, but thereby

there is no certainty of a 100% compliance and correct execution. In this study subjects performed

the exercises with 95% compliance. Also, both the balance boards were custom made: the curvature

of both types is exactly the same. Thus, a possible difficulty difference between the groups can be

excluded.

All tests pre- and post-intervention were performed in the same setting, and by the same

researchers. For example, all varus-click tests and anterior drawer tests were executed by one

researcher, the electrodes were always placed by the same researcher and the manual resistance

during the MVC’s was also given by the same researcher. An important limitation, however, is

working with surface EMG at two different moments (pre- and post-intervention). Although various

31

measures were taken to standardize the electrode locations, a small difference pre- and post-

intervention is inevitable. The EMG system utilised in this research was wired. Therefore, noise

interfering with the signals during movements cannot be excluded.(61) A wireless EMG system could

have been better.

Another limitation is the way of computing our normalized EMG data: division of raw EMG data by

the correspondent mean MVC value. Hence the muscle activity, measured during the jumps, is

expressed as a percentage of the mean MVC value. These mean MVC values are, at their turn,

calculated out of 3 mean MVC’s. These means can be an underestimation of the real maximal

voluntary contraction. This also means that if there are major changes in pre- and post-intervention

mean MVC values, they could mask an alteration of the EMG data. Therefore researchers

investigated both raw EMG data and mean MVC values separately as well.

Lack of kinematic information concerning ankle position immediately pre- and post-contact is

another limitation. Coupling such data to EMG data could clear certain things out, a better

understanding of how balance training influences the ankle in CAI could have been forged. Kinematic

data could further explain the findings found in the EMG data.

No EMG measurements were taken of more proximal muscles, such as knee, hip and trunk

musculature. Because MULTI-group subjects experienced numerous more effort maintaining balance

atop the balance board they subjectively adopted more of a hip strategy, compared to the UNI-group

subjects who easily held their balance and were able to employ more of an ankle strategy in

maintaining balance. Hence, better trained ankle musculature in UNI-group subjects seems evident.

On the other hand, important alterations in muscle activity could have occurred in more proximal

muscles for MULTI-group subjects but no EMG data was gathered on that subject.

Researchers made no use of a control group. Thus no comparison in effects caused by the balance

training program can be made between healthy and CAI subjects.

6.4. Practical implications and conclusion

It is clear that both interventions had an effect on muscle activation. No significant differences were

found between the uniaxial and multiaxial balance board. We thus cannot conclude if one balance

board is better than the other. We can conclude however, that subjects with CAI have benefit with

training on a balance board. In researchers’ opinion, it may be useful starting balance training using

the more simple uniaxial balance board, gradually substituting it with a multiaxial balance board.

Additionally, it can be interesting to evolve from more a more static balance training program to a

more dynamic alternative when progressing the rehabilitation, as this dynamic balance training is

thought to be more functional. For a better understanding which balance board type is ultimately

32

better, we recommend further research with a larger population and/or longer intervention

duration.

6.5. Acknowledgements

The authors of this study would like to thank Prof. Dr. P. Roosen (promotor) and Dr. R. De Ridder (co-

promotor) for their effort and time. Without their help this study would not have been possible. We

also would like to thank the Department of Rehabilitation Sciences and Physiotherapy of Ghent

University for the use of their research laboratories and material.

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8. Abstract in lekentaal Achtergrond: Balanstraining wordt regelmatig gebruikt in de revalidatie van chronische

enkelinstabiliteit (CAI). Het nut hiervan is de voorbije jaren al uitvoerig onderzocht geweest en

dusdanig bewezen, al zijn er nog veel onzekerheden in verband met welk type balanstraining het

effectiefst is. In deze studie evalueren we spieractiviteit na balanstraining waarbij proefpersonen op

één been stonden op een kantelplank enerzijds (die slechts in twee richtingen kan omslaan; links en

rechts) en een oefentol anderzijds (die in alle 360° kan omslaan).

Doel: Het doel van deze studie is het vergelijken van spieractivatie gedurende twee

sprongoefeningen, voor en na het uitvoeren van een zes-weken durende balanstraining.

Methode: 28 patiënten, allen met CAI klachten, werden gerekruteerd volgens strenge voorwaarden.

Deelnemers werden willekeurig opgedeeld in twee even grote groepen, een groep kantelplank en een

groep oefentol. Voor en na het uitvoeren van de zes weken balanstraining werd spieractiviteit

gemeten tijdens het uitvoeren van een voorwaartse en zijwaartse sprongoefening.

Resultaten: Beide groepen maakten vooruitgang gezien ze relatief minder spierkracht gebruikten

tijdens de sprongoefeningen. In de aangeboden vragenlijsten beschreven ze minder last te hebben

van hun enkelinstabiliteit. De vooruitgang blijkt groter te zijn in de kantelplank groep, erop wijzend

dat de kantelplank een voordeel kan opleveren tegenover de oefentol.

37

9. Ethical approval

39

10. Appendix

10.1. Inclusion criteria questionnaire Naam: Geboortedatum:

Emailadres: Lengte:

Telefoonnummer: Gewicht:

Omcirkel wat bij u past en/of vul in

1. Heeft u ooit uw enkel verzwikt (lees verstuikt)?

Links: ja nee

Rechts: ja nee

Indien u nog nooit uw enkel heeft verzwikt, hoeft u de rest van de vragenlijst niet meer in te vullen!

2. Heeft u ooit uw enkel verzwikt waardoor u gedurende ten minste 3 weken klachten (zoals

pijn, zwelling en stijfheid) in uw enkel heeft gehad en waardoor u gedurende dezelfde

periode uw beroep, sport, hobby of andere bewegingsactiviteiten heeft moeten staken?

Links: ja nee

Rechts: ja nee

Indien u hier 2x nee hebt ingevuld, hoeft u de rest van de vragenlijst niet meer in te vullen!

3. Verzwikt u sindsdien herhaald deze enkel?

Links: ja, ongeveer …. per jaar nee

Rechts: ja, ongeveer …. per jaar nee

4. Gaat dit herhaald verzwikken dan gepaard met klachten (pijn, zwelling, stijfheid) achteraf?

Links: ja, altijd ja, soms nooit

Rechts: ja, altijd ja, soms nooit

5. Heeft u een onzeker, instabiel gevoel in uw enkel?

Links: ja nee

Rechts: ja nee

6. Heeft u een gevoel van zwakte rond de enkel?

Links: ja nee

Rechts: ja nee

7. Hoelang wordt u met het herhaald verzwikken van uw enkel geconfronteerd (in maanden

en/of jaren uitgedrukt)?

Links: ongeveer….. jaar en/of ….. maand

Rechts ongeveer….. jaar en/of ….. maand

8. Wanneer hebt u voor het laatst uw enkel verzwikt? ……. maand/jaar geleden

40

9. De kwaliteit in het uitoefenen van mijn sport of hobby is door het frequent verzwikken van

mijn enkel verminderd ten opzichte van de periode van voor mijn enkelprobleem.

waar niet waar

10. De kwaliteit in het uitoefenen van mijn beroep is door het frequent verzwikken van mijn

enkel verminderd ten opzichte van de periode van voor mijn enkelprobleem.

waar niet waar

11. Ik ben van mening dat ik voor mijn enkelprobleem behandeld zou moeten worden

ja nee

12. Oefent u activiteiten uit (m.b.t. sport, hobby) bestaande uit lopen, springen of wandelen?

ja nee

13. Beoefent u sport op professioneel of semiprofessioneel niveau?

ja nee

Zo ja, welke?

14. Beoefent u een sport op competitief niveau?

ja nee

Zo ja, welke?

15. Beoefent u een sport op recreatief niveau?

ja nee

Zo ja, welke?

16. Hoe frequent oefent u uw sport of hobby uit?

o 4 à 7 maal per week o 1 à 3 maal per week o 1 à 3 maal per maand o Ik beoefen geen sport

41

10.2. CAIT questionnaire Naam:

Gelieve bij ELKE vraag ÉÉN stelling aan te duiden die het BEST uw enkels beschrijft.

LINKS RECHTS

1. Ik heb pijn aan mijn enkel

Nooit □ □

Bij het sporten □ □

Bij het lopen op oneffen ondergrond □ □

Bij het lopen op effen ondergrond □ □

Bij het stappen op oneffen ondergrond □ □

Bij het stappen op effen ondergrond □ □

2. Mijn enkel voelt ONSTABIEL aan

Nooit □ □

Soms bij het sporten (niet altijd) □ □

Vaak bij het sporten (elke keer) □ □

Soms bij dagelijkse activiteiten □ □

Vaak bij dagelijkse activiteiten □ □

3. Als ik SCHERPE bochten maak, voelt mijn enkel ONSTABIEL aan

Nooit □ □

Soms bij het lopen □ □

Vaak bij het lopen □ □

Bij het stappen □ □

4. Als ik trappen afdaal, voelt mijn enkel ONSTABIEL aan

Nooit □ □

Als ik snel stap □ □

Af en toe □ □

Altijd □ □

5. Mijn enkel voelt onstabiel aan als ik op ÉÉN been sta

Nooit □ □

Op de bal van mijn voet (tenenstand) □ □

Met mijn voet plat op de grond □ □

6. Mijn enkel voelt ONSTABIEL aan als

Nooit □ □

Ik van de ene kant naar de andere kant huppel □ □

Ik ter plaatse huppel □ □

Als ik spring □ □

7. Mijn enkel voelt ONSTABIEL aan als

Nooit □ □

Ik op oneffen ondergrond loop □ □

Ik jog op oneffen ondergrond □ □

Ik op oneffen ondergrond stap □ □

Ik op een vlakke ondergrond stap □ □

42

LINKS RECHTS

8. NORMAALGEZIEN, als ik mijn enkel begin te verstuiken, kan ik dit ... stoppen

Meteen □ □

Vaak □ □

Soms □ □

Nooit □ □

Ik heb nog nooit mijn enkel verstuikt □ □

9. Na een TYPISCH voorval van het verstuiken van mijn enkel, wordt mijn enkel weer ‘normaal’

Bijna meteen □ □

In minder dan één dag □ □

1–2 dagen □ □

Meer dan 2 dagen □ □

Ik heb nog nooit mijn enkel verstuikt □ □

10.3. FADI questionnaire Naam:

Gelieve elke vraag te beantwoorden met één antwoord dat het best aansluit bij hoe u zich de afgelopen week hebt gevoeld. Als de activiteit in kwestie beperkt wordt door iets anders dan uw voet of enkel, duid dan N/T*aan.

Geen enkel probleem

Niet zo moeilijk

Moeilijk Enorm moeilijk

Onmogelijk

1. Staan

2. Op effen grond wandelen

3. Blootsvoets op effen ondergrond wandelen

4. Helling opwandelen

5. Helling afwandelen

6. Trap opgaan

7. Trap afgaan

8. Op oneffen grond wandelen

9. Stoeprand open afgaan

10. Hurken

11. Slapen

12. Op de tenen gaan staan

13. Beginnen te wandelen

14. 5 minuten of minder wandelen

43

15. Ongeveer 10 minuten wandelen

16. 15 minuten of langer wandelen

17. Huishoudelijke taken

18. Dagelijkse activiteiten

19. Persoonlijke verzorging

20. Licht tot gematigd werk (staan, stappen)

21. Zwaar werk (duwen/trekken, klimmen, dragen)

22. Recreatieve activiteiten

GEEN PIJN

MILDE PIJN

GEMATIGDE PIJN

HEVIGE PIJN

ONDRAAGLIJKE PIJN

23. Gemiddeld pijnniveau

24. Pijn in rust

25. Pijn bij normale activiteiten

26. Pijn bij het begin van de dag

Sportmodule (FADI B)

Geen enkel probleem

Niet zo moeilijk

Moeilijk Enorm moeilijk

Onmogelijk

1. Lopen

2. Springen

3. Neerkomen

4. Hurken en plots stoppen

5. Plotseling van richting veranderen, zijwaartse bewegingen

6. Weinig belastende activiteiten

7. Mogelijkheid om activiteit uit te voeren met uw normale techniek

8. Mogelijkheid om aan uw favoriete sport deel te nemen zolang u wil

44

10.4. GROC questionnaire

Thank you for the opportunity to assist in your rehabilitation. The following rating scale allows us to

review the overall outcome of your condition with physical therapy intervention. It allows us to

review your physical therapy outcome, which helps guide our treatment to better serve our patients

in the future. The Global Rating of Change (GROC) has been well documented and extensively used in

research as an outcome measure as well as to compare outcome measures. Please rate the overall

condition of your injured body part or region FROM THE TIME THAT YOU BEGAN TREATMENT UNTIL

NOW (Check only one):

A very great deal worse (-7) About the same (0) A very great deal better (7)

A great deal worse (-6) A great deal better (6)

Quite a bit worse (-5) Quite a bit better (5)

Moderately worse (-4) Moderately better (4)

Somewhat worse (-3) Somewhat better (3)

A little bit worse (-2) A little bit better (2)

A tiny bit worse (-1) A tiny bit better (1)

10.5. VAS questionnaire Naam: Code:

1. Forward Jump

Hebt u pijn tijdens het uitvoeren van de oefening?

Geen pijn _________________________________________________ ondraaglijke pijn

Vindt u deze oefening moeilijk?

Niet moeilijk _________________________________________________ enorm moeilijk

Ervaart u een instabiel gevoel tijdens deze oefening?

Neen _________________________________________________ enorm instabiel

Heb u een vermoeid gevoel tijdens deze oefening?

Neen _________________________________________________ enorm vermoeid

45

2. Side Jump

Hebt u pijn tijdens het uitvoeren van de oefening?

Geen pijn _________________________________________________ ondraaglijke pijn

Vindt u deze oefening moeilijk?

Niet moeilijk _________________________________________________ enorm moeilijk

Ervaart u een instabiel gevoel tijdens deze oefening?

Neen _________________________________________________ enorm instabiel

Heb u een vermoeid gevoel tijdens deze oefening?

Neen _________________________________________________ enorm vermoeid

10.6. Varus-click test and anterior drawer test Anterior Drawer Test: UNI-GROUP MULTI-GROUP TOTAL

Negative Count 10 13 23

% 71,4% 92,9% 82,1%

Positive Count 4 1 5

% 28,6% 7,1% 17,9%

Total Count 14 14 28

% 100,0% 100,0% 100,0%

Varus Click Test: UNI-GROUP MULTI-GROUP TOTAL

Negative Count 8 10 18

% 61,5% 71,4% 66,7%

Positive Count 5 4 9

% 38,5% 28,6% 33,3%

Total Count 13 14 27

% 100,0% 100,0% 100,0%

46

10.7. Relative muscle activation values: PL, PB and GaMed

Peroneus

Longus

Mean (SD)

Pre

Intervention

Mean (SD)

Post

Intervention

Mean

difference

(95% CI)

Sign.

(P<0.012)

UNI Before

Impact

FJ 141.745

(20.808)

85.183

(20.808)

56.561 0.034

SJ 131.965

(17.619)

80.435

(17.619)

51.530 0.014

After

Impact

FJ 247.083

(45.903)

132.302

(45.903)

114.781 0.050

SJ 222.072

(37.543)

119.352

(37.543)

102.719 0.046

MULTI Before

Impact

FJ 94.903

(21.541)

80.582

(20.808)

14.320 0.585

SJ 90.758

(18.186)

75.201

(17.619)

15.557 0.445

After

Impact

FJ 136.520

(47.519)

118.262

(45.903)

18.258 0.752

SJ 127.930

(38.928)

108.920

(37.543)

19.010 0.707

Peroneus Brevis

Mean (SD) Pre

Intervention

Mean (SD) Post

Intervention


Sign. (P<0.012)

UNI Before Impact

FJ 120.504 (19.647)

63.372 (20.379)

57.132 0.042

SJ 103.844 (13.986)

65.300 (14.504)

38.544 0.050

After Impact

FJ 153.220 (19.032)

94.978 (19.717)

58.242 0.025

SJ 152.144 (16.628)

85.744 (17.221)

66.400 0.004*

MULTI Before Impact

FJ 106.331 (19.647)

68.193 (19.647)

38.138 0.157

SJ 107.227 (13.986)

66.872 (13.986)

40.355 0.037

After Impact

FJ 122.668 (19.032)

83.983 (19.032)

38.685 0.117

SJ 128.110 (16.628)

83.539 (16.628)

44.571 0.040

47

Gastrocnemius Lateralis

Mean (SD) Pre

Intervention

Mean (SD) Post

Intervention


Sign. (P<0.012)

UNI Before Impact

FJ 265.379 (45.754)

159.765 (45.754)

105.614 0.109

SJ 212.507 (45.632)

142.053 (45.632)

70.454 0.241

After Impact

FJ 231.410 (41.490)

104.351 (41.490)

127.059 0.021

SJ 233.259 (47.408)

121.671 (47.408)

111.588

0.054

MULTI Before Impact

FJ 269.272 (45.754)

136.928 (47.481)

132.345 0.050

SJ 222.577 (45.632)

120.012 (47.304)

102.566 0.099

After Impact

FJ 200.800 (41.490)

97.157 (42.979)

103.643 0.061

SJ 219.955 (47.408)

110.728 (49.013)

109.228 0.064

10.8. Absolute muscle activation values: UNI-group

Paired Samples Statistics Mean N Std. Deviation Std. Error Mean

Pair 1 FJ_TA_BC 124,2200 14 49,73789 13,29301

FJ_TA_BC_POST 104,7014 14 83,22536 22,24291

Pair 2 FJ_PL_BC 201,3590 14 67,96057 18,16323

FJ_PL_BC_POST 175,5550 14 56,48916 15,09736

Pair 3 FJ_PB_BC 205,050 13 132,8450 36,8446

FJ_PB_BC_POST 208,7954 13 107,38250 29,78255

Pair 4 FJ_GaMED_BC 454,9190 14 257,08184 68,70801

FJ_GaMED_BC_POST 390,0993 14 169,45897 45,28981

Pair 5 FJ_GaLAT_BC 297,1181 14 197,32473 52,73725

FJ_GaLAT_BC_POST 302,3750 14 178,33208 47,66125

Pair 6 FJ_TA_AC 399,5179 14 247,85335 66,24159

FJ_TA_AC_POST 273,3093 14 90,30364 24,13466

Pair 7 FJ_PL_AC 298,0952 14 94,79932 25,33618

FJ_PL_AC_POST 286,0721 14 123,74441 33,07208

Pair 8 FJ_PB_AC 259,8682 13 97,55935 27,05810

FJ_PB_AC_POST 296,2308 13 106,74347 29,60531

Pair 9 FJ_GaMED_AC 275,0138 14 112,86887 30,16548

FJ_GaMED_AC_POST 213,4086 14 82,48199 22,04424

Pair 10 FJ_GaLAT_AC 218,4257 14 109,26680 29,20278

FJ_GaLAT_AC_POST 192,6779 14 71,82953 19,19725

48

Pair 11 SJ_TA_BC 120,7757 14 67,31120 17,98968

SJ_TA_BC_POST 100,4186 14 78,38530 20,94935

Pair 12 SJ_PL_BC 190,2579 14 67,98289 18,16919

SJ_PL_BC_POST 181,3057 14 89,30414 23,86753

Pair 13 SJ_PB_BC 187,0765 13 94,73664 26,27522

SJ_PB_BC_POST 211,3631 13 99,42093 27,57441

Pair 14 SJ_GaMED_BC 379,2179 14 171,61098 45,86496

SJ_GaMED_BC_POST 388,5429 14 153,55172 41,03842

Pair 15 SJ_GaLAT_BC 252,9307 14 172,43994 46,08651

SJ_GaLAT_BC_POST 274,5318 14 168,01288 44,90333

Pair 16 SJ_TA_AC 461,2786 14 244,71309 65,40232

SJ_TA_AC_POST 331,8893 14 91,40765 24,42972

Pair 17 SJ_PL_AC 280,4536 14 101,51344 27,13061

SJ_PL_AC_POST 256,6929 14 110,11378 29,42914

Pair 18 SJ_PB_AC 276,8062 13 108,31044 30,03991

SJ_PB_AC_POST 276,5808 13 108,74521 30,16050

Pair 19 SJ_GaMED_AC 283,3750 14 111,83565 29,88933

SJ_GaMED_AC_POST 286,0086 14 86,28121 23,05962

Pair 20 SJ_GaLAT_AC 223,3768 14 110,20399 29,45325

SJ_GaLAT_AC_POST 236,1100 14 89,90204 24,02733

49

Paired Samples Test: Paired Differences

Mean Std.

Deviation

Std. Error

Mean

95% CI

Lower

Pair 1 FJ_TA_BC -

FJ_TA_BC_POST

19,51857 87,57657 23,40582 -31,04663

Pair 2 FJ_PL_BC -

FJ_PL_BC_POST

25,80405 52,24108 13,96202 -4,35906

Pair 3 FJ_PB_BC -

FJ_PB_BC_POST

-3,74513 126,84343 35,18004 -80,39585

Pair 4 FJ_GaMED_BC -

FJ_GaMED_BC_POST

64,81976 192,43862 51,43139 -46,29099

Pair 5 FJ_GaLAT_BC -

FJ_GaLAT_BC_POST

-5,25690 115,74773 30,93488 -72,08765

Pair 6 FJ_TA_AC -

FJ_TA_AC_POST

126,20857 194,52593 51,98924 13,89265

Pair 7 FJ_PL_AC -

FJ_PL_AC_POST

12,02310 97,13043 25,95920 -44,05835

Pair 8 FJ_PB_AC -

FJ_PB_AC_POST

-36,36256 94,61486 26,24144 -93,53775

Pair 9 FJ_GaMED_AC -

FJ_GaMED_AC_POST

61,60524 108,20993 28,92032 -,87331

Pair 10 FJ_GaLAT_AC -

FJ_GaLAT_AC_POST

25,74786 117,92138 31,51581 -42,33792

Pair 11 SJ_TA_BC -

SJ_TA_BC_POST

20,35714 52,13573 13,93386 -9,74513

Pair 12 SJ_PL_BC -

SJ_PL_BC_POST

8,95214 44,74578 11,95881 -16,88330

Pair 13 SJ_PB_BC -

SJ_PB_BC_POST

-24,28654 109,75116 30,43950 -90,60850

Pair 14 SJ_GaMED_BC -

SJ_GaMED_BC_POST

-9,32500 129,54469 34,62227 -84,12188

Pair 15 SJ_GaLAT_BC -

SJ_GaLAT_BC_POST

-21,60107 121,80682 32,55424 -91,93024

Pair 16 SJ_TA_AC -

SJ_TA_AC_POST

129,38929 207,83075 55,54510 9,39139

Pair 17 SJ_PL_AC -

SJ_PL_AC_POST

23,76071 74,96309 20,03473 -19,52169

Pair 18 SJ_PB_AC -

SJ_PB_AC_POST

,22538 65,83876 18,26039 -39,56058

Pair 19 SJ_GaMED_AC -

SJ_GaMED_AC_POST

-2,63357 86,27138 23,05700 -52,44518

Pair 20 SJ_GaLAT_AC -

SJ_GaLAT_AC_POST

-12,73321 120,13452 32,10730 -82,09682

50

95% CI t df Sig. (2-tailed)

Upper

Pair 1 FJ_TA_BC -

FJ_TA_BC_POST

70,08378 ,834 13 ,419

Pair 2 FJ_PL_BC -

FJ_PL_BC_POST

55,96715 1,848 13 ,087

Pair 3 FJ_PB_BC -

FJ_PB_BC_POST

72,90559 -,106 12 ,917


FJ_GaMED_BC_POST

175,93051 1,260 13 ,230


FJ_GaLAT_BC_POST

61,57384 -,170 13 ,868

Pair 6 FJ_TA_AC -

FJ_TA_AC_POST

238,52450 2,428 13 ,030

Pair 7 FJ_PL_AC -

FJ_PL_AC_POST

68,10454 ,463 13 ,651

Pair 8 FJ_PB_AC -

FJ_PB_AC_POST

20,81262 -1,386 12 ,191


FJ_GaMED_AC_POST

124,08379 2,130 13 ,053


FJ_GaLAT_AC_POST

93,83363 ,817 13 ,429

Pair 11 SJ_TA_BC -

SJ_TA_BC_POST

50,45942 1,461 13 ,168

Pair 12 SJ_PL_BC -

SJ_PL_BC_POST

34,78759 ,749 13 ,467

Pair 13 SJ_PB_BC -

SJ_PB_BC_POST

42,03543 -,798 12 ,440


SJ_GaMED_BC_POST

65,47188 -,269 13 ,792


SJ_GaLAT_BC_POST

48,72809 -,664 13 ,519

Pair 16 SJ_TA_AC -

SJ_TA_AC_POST

249,38719 2,329 13 ,037

Pair 17 SJ_PL_AC -

SJ_PL_AC_POST

67,04312 1,186 13 ,257

Pair 18 SJ_PB_AC -

SJ_PB_AC_POST

40,01135 ,012 12 ,990


SJ_GaMED_AC_POST

47,17804 -,114 13 ,911


SJ_GaLAT_AC_POST

56,63039 -,397 13 ,698

51

10.9. Absolute muscle activation: MULTI-group

Paired Samples Statistics Mean N Std. Deviation Std. Error Mean

Pair 1 FJ_TA_BC 92,7700 14 26,77517 7,15596

FJ_TA_BC_POST 93,5471 14 32,56687 8,70386

Pair 2 FJ_PL_BC 199,8231 13 74,48416 20,65819

FJ_PL_BC_POST 185,0785 13 60,22515 16,70345

Pair 3 FJ_PB_BC 220,681 14 85,9812 22,9794

FJ_PB_BC_POST 240,6814 14 95,40438 25,49789

Pair 4 FJ_GaMED_BC 342,3429 14 132,50859 35,41441

FJ_GaMED_BC_POST 390,1000 14 202,98157 54,24911

Pair 5 FJ_GaLAT_BC 235,8429 14 64,45789 17,22710

FJ_GaLAT_BC_POST 269,6171 14 109,80271 29,34601

Pair 6 FJ_TA_AC 287,9857 14 101,62548 27,16055

FJ_TA_AC_POST 294,3143 14 69,81724 18,65944

Pair 7 FJ_PL_AC 282,8231 13 68,15490 18,90277

FJ_PL_AC_POST 289,8154 13 61,26279 16,99124

Pair 8 FJ_PB_AC 253,2829 14 67,81490 18,12429

FJ_PB_AC_POST 292,0143 14 96,92708 25,90485

Pair 9 FJ_GaMED_AC 227,4714 14 80,43085 21,49605

FJ_GaMED_AC_POST 233,4857 14 103,30907 27,61051

Pair 10 FJ_GaLAT_AC 178,5714 14 55,43792 14,81641

FJ_GaLAT_AC_POST 184,4514 14 44,07473 11,77947

Pair 11 SJ_TA_BC 99,9100 14 36,78138 9,83024

SJ_TA_BC_POST 94,9100 14 38,20545 10,21084

Pair 12 SJ_PL_BC 193,1108 13 59,26324 16,43666

SJ_PL_BC_POST 180,0154 13 46,55094 12,91091

Pair 13 SJ_PB_BC 227,3714 14 94,10037 25,14938

SJ_PB_BC_POST 235,9714 14 88,21250 23,57578

Pair 14 SJ_GaMED_BC 288,8657 14 103,15057 27,56815

SJ_GaMED_BC_POST 338,6857 14 143,66749 38,39675

Pair 15 SJ_GaLAT_BC 207,1857 14 58,03211 15,50973

SJ_GaLAT_BC_POST 236,5571 14 70,47357 18,83485

Pair 16 SJ_TA_AC 342,5857 14 102,20488 27,31540

SJ_TA_AC_POST 362,0729 14 80,96432 21,63862

Pair 17 SJ_PL_AC 267,7846 13 79,06645 21,92909

SJ_PL_AC_POST 264,8000 13 35,29750 9,78976

Pair 18 SJ_PB_AC 263,6143 14 66,18949 17,68989

SJ_PB_AC_POST 291,8857 14 81,84934 21,87516

52

Pair 19 SJ_GaMED_AC 234,6286 14 90,26361 24,12396

SJ_GaMED_AC_POST 252,3600 14 85,21805 22,77548

Pair 20 SJ_GaLAT_AC 193,1886 14 56,63843 15,13726

SJ_GaLAT_AC_POST 198,2600 14 45,30956 12,10949

Paired Samples Test: Paired Differences

Mean Std.

Deviation

Std. Error

Mean

95% CI

Lower

Pair 1 FJ_TA_BC -

FJ_TA_BC_POST

-,77714 23,60423 6,30850 -14,40582

Pair 2 FJ_PL_BC -

FJ_PL_BC_POST

14,74462 82,19100 22,79568 -34,92291

Pair 3 FJ_PB_BC -

FJ_PB_BC_POST

-20,00000 83,98700 22,44647 -68,49265


FJ_GaMED_BC_POST

-47,75714 174,16938 46,54873 -148,31955


FJ_GaLAT_BC_POST

-33,77429 114,24262 30,53262 -99,73601

Pair 6 FJ_TA_AC -

FJ_TA_AC_POST

-6,32857 107,13174 28,63216 -68,18460

Pair 7 FJ_PL_AC -

FJ_PL_AC_POST

-6,99231 87,07168 24,14934 -59,60920

Pair 8 FJ_PB_AC -

FJ_PB_AC_POST

-38,73143 84,55292 22,59772 -87,55083


FJ_GaMED_AC_POST

-6,01429 78,46243 20,96997 -51,31714


FJ_GaLAT_AC_POST

-5,88000 65,05761 17,38738 -43,44315

Pair 11 SJ_TA_BC -

SJ_TA_BC_POST

5,00000 37,13150 9,92381 -16,43909

Pair 12 SJ_PL_BC -

SJ_PL_BC_POST

13,09538 61,09045 16,94344 -23,82121

Pair 13 SJ_PB_BC -

SJ_PB_BC_POST

-8,60000 78,10581 20,87465 -53,69695


SJ_GaMED_BC_POST

-49,82000 113,30102 30,28097 -115,23806


SJ_GaLAT_BC_POST

-29,37143 77,96212 20,83625 -74,38541

53

Pair 16 SJ_TA_AC -

SJ_TA_AC_POST

-19,48714 85,57038 22,86964 -68,89401

Pair 17 SJ_PL_AC -

SJ_PL_AC_POST

2,98462 90,99405 25,23721 -52,00254

Pair 18 SJ_PB_AC -

SJ_PB_AC_POST

-28,27143 75,55944 20,19411 -71,89815


SJ_GaMED_AC_POST

-17,73143 69,75021 18,64153 -58,00400


SJ_GaLAT_AC_POST

-5,07143 76,16940 20,35713 -49,05033

95% CI t df Sig. (2-tailed)

Upper

Pair 1 FJ_TA_BC -

FJ_TA_BC_POST

12,85153 -,123 13 ,904

Pair 2 FJ_PL_BC -

FJ_PL_BC_POST

64,41214 ,647 12 ,530

Pair 3 FJ_PB_BC -

FJ_PB_BC_POST

28,49265 -,891 13 ,389


FJ_GaMED_BC_POST

52,80526 -1,026 13 ,324


FJ_GaLAT_BC_POST

32,18744 -1,106 13 ,289

Pair 6 FJ_TA_AC -

FJ_TA_AC_POST

55,52745 -,221 13 ,829

Pair 7 FJ_PL_AC -

FJ_PL_AC_POST

45,62458 -,290 12 ,777

Pair 8 FJ_PB_AC -

FJ_PB_AC_POST

10,08798 -1,714 13 ,110


FJ_GaMED_AC_POST

39,28857 -,287 13 ,779


FJ_GaLAT_AC_POST

31,68315 -,338 13 ,741

Pair 11 SJ_TA_BC -

SJ_TA_BC_POST

26,43909 ,504 13 ,623

Pair 12 SJ_PL_BC -

SJ_PL_BC_POST

50,01198 ,773 12 ,455

Pair 13 SJ_PB_BC -

SJ_PB_BC_POST

36,49695 -,412 13 ,687


SJ_GaMED_BC_POST

15,59806 -1,645 13 ,124

54


SJ_GaLAT_BC_POST

15,64256 -1,410 13 ,182

Pair 16 SJ_TA_AC -

SJ_TA_AC_POST

29,91972 -,852 13 ,410

Pair 17 SJ_PL_AC -

SJ_PL_AC_POST

57,97177 ,118 12 ,908

Pair 18 SJ_PB_AC -

SJ_PB_AC_POST

15,35529 -1,400 13 ,185


SJ_GaMED_AC_POST

22,54114 -,951 13 ,359


SJ_GaLAT_AC_POST

38,90747 -,249 13 ,807

10.10. VAS-scores

Pre-intervention Mean (SD)

Post-intervention Mean (SD)

Mean Difference (95% CI)

Sign. (P<0.05)

UNI Pain FJ 16.36 (23.180)

2.86 (3.009)

13.500 (0.519 , 26.481)

0.309

Pain SJ 14.50 (16.883)

1.79 (1.477)

12.714 (3.475, 21.954)

0.017*

Fatigue FJ 18.07 (19.357)

5.79 (8.304)

12.286 (0.662 , 23.910)

0.685

Fatigue SJ 27.14 (23.605)

9.21 (11.342)

17.929 (3.712, 32.145)

0.612

Difficulty FJ 33.21 (24.106)

18.71 (11.180)

14.500 (1.034 , 27.966)

0.296

Difficulty SJ 48.14 (26.628)

24.64 (18.236)

23.500 (4.465 , 42.535)

0.874

Instability FJ

46.64 (19.357)

16.43 (11.992)

30.214 (18.512 , 41.917)

0.076

Instability SJ

51.57 (26.323)

9.21 (11.342)

35.857 (22.101 , 49.614)

0.130

55

MULTI Pain FJ 13.50 (14.737)

5.29 (11.027)

8.214 (-1.440 , 17.868)

0.533

Pain SJ 16.69 (17.632)

11.85 (13.465)

4.846 (-8.095 , 17.788)

0.819

Fatigue FJ 21.00 (24.172)

8.14 (8.655)

12.857 (-2.511, 28.225)

0.689

Fatigue SJ 18.85 (23.745)

10.00 (10.824)

8.846 (-8.363 , 26.055)

0.404

Difficulty FJ 32.86 (23.035)

14.07 (13.731)

18.786 (6.979 , 30.593)

0.086

Difficulty SJ 35.46 (22.769)

20.00 (14.804)

15.462 (2.063 , 28.860)

0.220

Instability FJ

47.79 (17.529)

11.71 (10.410)

36.071 (24.253 , 47.890)

0.975

Instability SJ

42.69 (22.914)

19.38 (13.727)

23.308 (8.029 , 38.586)

0.701

10.11. Baseline differences post-intervention

UNI Mean (Std. Error)

MULTI Mean (Std. Error)


Sign. (P<0.012)

TA FJ before contact 26.034 (7.436)

24.037 (7.436)

1.998 (-19.355 , 23.350)

0.850

FJ post contact 60.820 (12.644)

77.108 (12.644)

-16.288 (-52.379 , 19.804)

0.368

SJ before contact 24.839 (10.808)

25.281 (10.808)

0.442 (-31.461 , 30.576)

0.977

SJ post contact 76.101 (21.462)

93.435 (21.462)

-17.333 (-78.506 , 43.839)

0.571

PL FJ before contact 85.183 (20.808)

80.582 (20.808)

4.601 (-54.570 , 63.772)

0.876


118.262 (45.903)

14.040 (-116.489 , 144.569)

0.830


75.201 (17.619)

5.235 (-44.960 , 55.430)

0.835


108.920 (37.543)

10.433 (-96.212 , 117.077)

0.845

56

PB FJ before contact 63.372 (20.379)

68.193 (19.647)

-4.821 (-61.665 , 52.024)

0.865


83.983 (19.032)

10.995 (-44.075 , 66.066)

0.690


66.872 (13.986)

-1.572 (-42.038 , 38.895)

0.935


83.539 (16.628)

2.204 (-45.915 , 50.324)

0.927

GaMed FJ before contact 106.610 (18.857)

154.777 (19.547)

-48.168 (-102.728 , 6.393)

0.082


88.264 (18.107)

-16.311 (-67.361 , 34.738)

0.522


132.275 (16.934)

-20.303 (-67.782 , 27.176)

0.394


100.719 (16.831)

-10.007 (-57.541 , 37.527)

0.673

GaLat FJ before contact 159.765 (45.754)

136.928 (47.481)

22.837 (-109.540 , 155.215)

0.731


97.157 (42.979)

7.194 (-112.857 , 127.244)

0.905


120.012 (47.304)

22.042 (-109.987 , 154.070)

0.739


110.728 (49.013)

10.944 (-126.242 , 148.129)

0.873

10.12. Linear Mixed Models: Fixed Effects

Intervention * Time (Sig.)

Intervention (Sig). Time (Sig.)

FJ_TA_BC 0.523 0.638 0.002

FJ_PL_BC 0.254 0.284 0.061

FJ_PB_BC 0.616 0.825 0.017

FJ_GaMed_BC 0.516 0.086 0.000

FJ_GaLat_BC 0.773 0.838 0.013

FJ_TA_AC 0.103 0.944 0.000

FJ_PL_AC 0.238 0.241 0.108

FJ_PB_AC 0.571 0.335 0.009

FJ_GaMed_AC 0.914 0.501 0.000

FJ_GaLat_AC 0.754 0.686 0.004

SJ_TA_BC 0.301 0.675 0.006

SJ_PL_BC 0.210 0.276 0.024

SJ_PB_BC 0.946 0.871 0.006

SJ_GaMed_BC 0.890 0.394 0.001

SJ_GaLat_BC 0.705 0.905 0.049

SJ_TA_AC 0.167 0.825 0.004

SJ_PL_AC 0.242 0.209 0.094

SJ_PB_AC 0.465 0.488 0.001

SJ_GaMed_AC 0.811 0.546 0.000

SJ_GaLat_AC 0.976 0.827 0.010

the effects of a six-week balance training … · balance training protocol on chronic ankle...

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