FISIOLOGIA DELLO STRETCHINGFISIOLOGIA DELLO STRETCHING

Prof. Fabio EspositoProf. Fabio Esposito

Dipartimento di Scienze dello Sport, Nutrizione e SaluDipartimento di Scienze dello Sport, Nutrizione e Salutete

FacoltFacoltàà di Scienze Motoriedi Scienze Motorie

UniversitUniversitàà degli Studi di Milanodegli Studi di Milano

INTRODUCTIONINTRODUCTION

Acute passive stretching:Acute passive stretching:

•• Increases joint range of motionIncreases joint range of motion

•• Reduces risks of injuriesReduces risks of injuries

•• Improves performanceImproves performance

decreases maximum force and powerdecreases maximum force and powerreduces performancereduces performance

Fowles, J Appl Physiol (2000)Fowles, J Appl Physiol (2000)Kokkonen, Res Q Exerc Sport (2001)Kokkonen, Res Q Exerc Sport (2001)Nelson, J Sports Sci (2004)Nelson, J Sports Sci (2004)CCèè, J Sports Sci (2008), J Sports Sci (2008)Costa, Int J Sports Med (2009)Costa, Int J Sports Med (2009)

Two main mechanisms:Two main mechanisms:

Neural changes:Neural changes:

Decreased motoDecreased moto--neuron excitability (preneuron excitability (pre-- and postand post--synaptic synaptic

mechanisms)mechanisms)

MuscleMuscle--tendon unit changes:tendon unit changes:

Increased muscleIncreased muscle--tendon unit compliance, reduction in passive tendon unit compliance, reduction in passive

tension, alteration of muscle elasticity and tension/length tension, alteration of muscle elasticity and tension/length

relationshiprelationship

Mainly type II motor unitsMainly type II motor units

AIMAIM

To assess stretchingTo assess stretching--induced effects on induced effects on maximum aerobic power and endurancemaximum aerobic power and endurance

METHODSMETHODSTen active males Ten active males (age 23(age 23±±5 yrs; body mass 695 yrs; body mass 69±±7 kg; stature 1717 kg; stature 171±±9 cm; mean9 cm; mean±±SD)SD)

Ten tests (5 with and 5 without stretching) on a cycle ergometeTen tests (5 with and 5 without stretching) on a cycle ergometer (100 r (100 ±±

3 rpm), in a random order3 rpm), in a random order

•• Two squareTwo square--wave maximum incremental testswave maximum incremental tests

•• Two ramp maximum incremental testsTwo ramp maximum incremental tests

•• Six tests at 85% VSix tests at 85% VOO2 max2 max (W(W8585), until exhaustion), until exhaustion

Stretching routine: 5 x (45 s on / 15 s off)Stretching routine: 5 x (45 s on / 15 s off)

Measurements: gas exchange, cardioMeasurements: gas exchange, cardio--respiratory parameters, lactate respiratory parameters, lactate

concentrationconcentration

.. ..

.

RAMP MAXIMUM INCREMENTAL TESTRAMP MAXIMUM INCREMENTAL TEST

Power Power maxmax

Heart Rate Heart Rate maxmax Peak [La]Peak [La]

Peak OPeak O22 uptakeuptake*

*

WW8585

..

**

Exercise durationExercise duration

Oxygen uptake

% T tot0 10 20 30 40 50 60 70 80 90 100

VO

2 (m

l/min

)

1500

2000

2500

3000

3500

4000

controlsstretching

* * * * *

.

Oxygen uptake

% T tot0 10 20 30 40 50 60 70 80 90 100

VO

2 (m

l/min

)

1500

2000

2500

3000

3500

4000

controlsstretching

* * * * *

.

Blood Lactate

% T tot0 10 20 30 40 50 60 70 80 90 100

[La- ] (

mM

)

2

4

6

8

10

12

controlsstretching

*

Blood Lactate

% T tot0 10 20 30 40 50 60 70 80 90 100

[La- ] (

mM

)

2

4

6

8

10

12

controlsstretching

*

Respiratory Rate

% T tot0 10 20 30 40 50 60 70 80 90 100

RR

(b/m

in)

20

30

40

50

60

70

80

controlsstretching

*

* * *** *

*

Respiratory Rate

% T tot0 10 20 30 40 50 60 70 80 90 100

RR

(b/m

in)

20

30

40

50

60

70

80

controlsstretching

*

* * *** *

*

Tidal Volume

% T tot0 10 20 30 40 50 60 70 80 90 100

VT (

l)

1.5

2.0

2.5

3.0

controlsstretching

Tidal Volume

% T tot0 10 20 30 40 50 60 70 80 90 100

VT (

l)

1.5

2.0

2.5

3.0

controlsstretching

Expired Ventilation

% T tot0 10 20 30 40 50 60 70 80 90 100

VE

(l/m

in)

20

40

60

80

100

120

140

controlsstretching

*

.*

Expired Ventilation

% T tot0 10 20 30 40 50 60 70 80 90 100

VE

(l/m

in)

20

40

60

80

100

120

140

controlsstretching

*

.*

Heart Rate

% T tot0 10 20 30 40 50 60 70 80 90 100

HR

(bpm

)

100

120

140

160

180

200

controlsstretching

Heart Rate

% T tot0 10 20 30 40 50 60 70 80 90 100

HR

(bpm

)

100

120

140

160

180

200

controlsstretching

time (min) 2 4 6 8 10

e net

0.16

0.18

0.20

0.22

* ****

Net efficiencyNet efficiency

With acute passive stretching:With acute passive stretching:

Maximum aerobic power is not affectedMaximum aerobic power is not affectedEndurance time of a highEndurance time of a high--intensity exercise is intensity exercise is

significantly reducedsignificantly reducedExercise efficiency is decreasedExercise efficiency is decreasedType II motor units are impairedType II motor units are impaired

ACKNOWLEDGEMENTSACKNOWLEDGEMENTS

•• Dr. Eloisa LimontaDr. Eloisa Limonta

•• Dr. Emiliano CDr. Emiliano Cèè

•• Dr. Luca AgnelloDr. Luca Agnello

•• Prof. Arsenio VeicsteinasProf. Arsenio Veicsteinas