The influence of stretching and warm-up exercises on Achilles tendon reflex activity
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CONTRIBUTORS:
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JOURNAL:
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YEAR:
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1995
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PUB TYPE:
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Journal Article
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SUBJECT(S):
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ACHILLES-TENDON; INJURY; PREVENTION; STRETCHING; WARM-UP
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DISCIPLINE:
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No discipline assigned
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HTTP:
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LANGUAGE:
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English
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PUB ID:
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103-366-486
(Last edited on
2002/02/27 18:45:01 US/Mountain)
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SPONSOR(S):
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ABSTRACT:
The aim of this study was to investigate the acute effects of prior exercise (warm-up and stretching) on the electromyographic and force output of mechanically elicited triceps surae reflexes. Fifty male subjects performed eight reflex experiments under each of three successive conditions in one session: (1) no prior exercise, (2) after static stretching of the passive triceps surae (3 min) and (3) after a 10-min warm-up run on a treadmill. Tendon tap reflex force was elicited in the triceps surae of the right leg by means of a standardized reflex hammer and measured in a custom-built fixture. Electromyographic (EMG) signals were recorded with surface electrodes over the medial head of the gastrocnemius (G) and the soleus (S). Low coefficients of variation within subjects contrasted with high between-subject variations, indicating highly individual reflex characteristics. After stretching, reductions in the peak force (- 5 percent; P is less than 0.05), the force rise rate (-8 percent; P is less than 0.01), the half relaxation rate (-5 percent; N.S.), the EMG amplitudes (G, -16 percent; S, -17 percent; P is less than 0.01) and integrals (G, -15 percent; S, -18 percent; P is less than 0.01), and an increase in EMG latencies (G, +3 percent; S, +1 percent; P is less than 0.01), were found compared with the values obtained without prior exercise. After running, the peak force reached the values obtained without prior exercise (-2 percent; N.S.), the force rise rate and half relaxation rate increased by 8 and 12 percent, respectively (P is less than 0.01), and the impulse (force-time integral; -12 percent), EMG amplitudes (G, -20 percent; S, -23 percent; P is less than 0.01), integrals (G, -18 percent; S, -23 percent; P is less than 0.01) and latencies (G, -1 percent; S, -2 percent; P is less than 0.01) decreased significantly. The changes in the force characteristics observed after the stretching treatment indicate improved muscle compliance that might reduce the risk of injury. On the other hand, the changes after the additional warm-up run had a more pronounced influence with regard to improved force development and a decreased EMG activity, which can be viewed as a performance-enhancing effect.
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