Surface Electromyogram of Lumbar Muscles ofPeople with and without Low Back Pain During

Running Exercise

W M Poon #, D K Kumar #, S P Arjunan #1,H Rudolph #, Y Hu*

# School of Electrical and Computer Engineering, RMIT UniversityGPO Box 2476, Melbourne, Australia, VIC 3001

1 sridhar_arjunan@ieee.org*Neural Engineering & Clinical Electrophysiology Lab,

University of Hong Kong

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Outline

• Abstract• Materials and Methods• Data Analysis• Results• Discussion

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Abstract

• Low back pain (LBP) can be dilapidating and causes major hardships to the sufferers. It is the single biggest cause for people taking time from work, resulting in large financial losses.

• There is an urgent need for evaluating the lower back at an early stage to mitigate the impact of LBP and reduce the possible recurrence.

• Current diagnostic techniques are cumbersome and expensive, and not suitable for routine clinical analysis.

• This paper describes the use of surface electromyogram (sEMG) for identifying people suffering with Lower Back Pain (LBP).

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Materials and Methods

• In 2005, WorkCover Victoria, Australia, reported that for the previous ten years, 26% of all claims directly related to back injury or disease and $1.3 billion had been paid for back injury or disease.

• Low back pain (LBP) has been associated with weakness of the muscles of the lumbar region.

• One proposed technique to identify muscle dysfunction is electromyogram (EMG). EMG is a measure of the electrical activity associated with muscle contraction.

• Researchers have determined significant difference in the sEMG of people suffering from LBP and people with no LBP patients when they were made to walk.

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Materials and Methods

• Patients with chronic LBP may alter the neuromuscular control of gross motor activities such as locomotion, by way of ’protective guarding’ or ’splinting’.

• These changes have been observed to be significant and may be used to identify people with back muscles ailments.

• The activity of the associated lumbar musculature such as erector spinae (ES) and Posoas major muscle have proven to be useful in the study of human gait.

• This paper proposes that one of the reasons for the lack of agreement between the various studies in the use of sEMG during walking is because of a lack of well defined protocol.

• This paper suggests that the difference between the two cohorts would be evident only if the exercise was sufficient to cause fatigue in the LBP cohort while not causing fatigue in the healthy cohort.

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Materials and Methods - Experiments

• The experiments were conducted at Gait Analysis Laboratory in Duchess of Kent Children’s Hospital Hong Kong.

• Eight volunteer subjects (Four healthy and four LBP) participated in the trial.

• Healthy subjects : they must NOT have any history of LBP or any other musculoskeletal disorders.

• LBP Subjects: non-specific mild to moderate LBP for more than 6 weeks and less than 4 months and for whom the medical treatment had not yet been started.

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Materials and Methods - Experiments

• Participants in both; healthy and LBP cohorts, were required to run on the treadmill (Life Fitness T7 treadmill).

• Duration : ten minutes or till the participant got fatigued.

• The participants were asked to jog in their usual style.

• Speed : 8 Km/hour or less if the subjects had difficulty at this speed.

• The subjects were allowed to stop when they felt pain or excessive fatigue.

Placement of electrodes at fourth Lumbar vertebra (L4) in both right and left

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Data segments for activation and deactivation periods

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Data Analysis

• Length of data chosen: one minute (large enough to be statistically significant with approximately 20 steps in the duration, while it is short enough to represent stationary status of the muscle.

• The first minute at the start represents the muscle prior to the exercise

• The tenth (last) minute represents the muscle at the end of the exercise

• Root Mean Square (RMS) of the signal was computed using a narrow moving window of 5 samples. RMS of the signal was used to identify the following:

• The activation and deactivation of the muscles. • Total activation period of each channel for each one minute

segment.• Average RMS value of each minute segment.

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Results

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Results

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Observations

• From Table I, it is observed that the value of variance of the LBP subjects is significantly higher than the healthy subjects.

• From Table II, it is observed that there was an increase of variance during running for LBP participants. This may be attributable to the participants with LBP getting fatigued early due to which they changed their muscle recruitment strategy.

• From Figure.3, it is observed that for the fixed rate running exercise the increase in variance of the amplitudes of sEMG for the CLBP.

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Results

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Discussion

• From the above results it is evident that there is a significant difference in the muscle activation between the LBP and no LBP cohorts.

• The variance in the sEMG of the LBP subjects is significantly higher than the healthy back people, which may be attributable to the muscle weakness of these people.

• The results also demonstrate that there is a significant change in the variance for both the cohorts over the duration of the exercise, but the change in the LBP is much greater than in the healthy subjects.

• From these results, it is concluded that variance and change of variance over time of sEMG recorded from L4/ L5 region during running may be used to identify the LBP patients.

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Thank You for your attention.

We hope that we did not cause you any low back pain due to sitting and listening this

presentation