Neuromuscular adjustments of the quadriceps muscle after repeated cycling sprints.
<h4>Purpose</h4>This study investigated the supraspinal processes of fatigue of the quadriceps muscle in response to repeated cycling sprints.<h4>Methods</h4>Twelve active individuals performed 10 × 6-s "all-out" sprints on a cycle ergometer (recovery = 30 s), follo...
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| Autores principales: | , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Public Library of Science (PLoS)
2013
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/0a19800f9f0d4e61af93e8f1b0a20f0c |
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| Sumario: | <h4>Purpose</h4>This study investigated the supraspinal processes of fatigue of the quadriceps muscle in response to repeated cycling sprints.<h4>Methods</h4>Twelve active individuals performed 10 × 6-s "all-out" sprints on a cycle ergometer (recovery = 30 s), followed 6 min later by 5 × 6-s sprints (recovery = 30 s). Transcranial magnetic and electrical femoral nerve stimulations during brief (5-s) and sustained (30-s) isometric contractions of the knee extensors were performed before and 3 min post-exercise.<h4>Results</h4>Maximal strength of the knee extensors decreased during brief and sustained contractions (~11% and 9%, respectively; P<0.001). Peripheral and cortical voluntary activation, motor evoked potential amplitude and silent period duration responses measured during briefs contractions were unaltered (P>0.05). While cortical voluntary activation declined (P<0.01) during the sustained maximal contraction in both test sessions, larger reductions occurred (P<0.05) after exercise. Lastly, resting twitch amplitude in response to both femoral nerve and cortical stimulations was largely (> 40%) reduced (P<0.001) following exercise.<h4>Conclusion</h4>The capacity of the motor cortex to optimally drive the knee extensors following a repeated-sprint test was shown in sustained, but not brief, maximal isometric contractions. Additionally, peripheral factors were largely involved in the exercise-induced impairment in neuromuscular function, while corticospinal excitability was well-preserved. |
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