Muscle deoxygenation and neural drive to the muscle during repeated sprint cycling.
OBJECTIVE
To investigate muscle deoxygenation and neural drive-related changes during repeated cycling sprints in a fatiguing context.


METHODS
Nine healthy male subjects performed a repeated-sprint test (consisting of 10 x 6-s maximal sprints interspaced by 30 s of recovery). Oxygen uptake was measured breath-by-breath; muscle deoxygenation of the vastus lateralis was assessed continuously using the near-infrared spectroscopy technique. Surface electromyograms (RMS) of both vastus lateralis and biceps femoris were also recorded. Furthermore, before and after the repeated-sprint test, the percentage of muscle activation by voluntary drive (twitch-interpolated method) was measured during a maximal voluntary contraction.


CONCLUSIONS
Consistent with previous research, our data showed a significant power decrement during repeated-sprint exercise. There was also a progressive muscle deoxygenation, but our data showed that the ability of the subjects to use available O2 throughout the entire repeated-sprint test was well preserved. Our data displayed a significant decrement in the RMS activity during the acceleration phase of each sprint across the repeated-sprint exercise. Moreover, decrement in motor drive was confirmed after exercise by a significant decrease in both percentage of voluntary activation and RMS/M-wave ratio during a maximal voluntary contraction.


CONCLUSIONS
In this experimental design, our findings suggest that the ability to repeat short-duration (6 s) sprints was associated with the occurrence of both peripheral and central fatigue.
Racinais
Sébastien
S
Motor Efficiency and Deficiency Laboratory, Montpellier, France. contact@sebastienracinais.com
Bishop
David
D
Denis
Romain
R
Lattier
Grégory
G
Mendez-Villaneuva
Alberto
A
Perrey
Stéphane
S
D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology*; D001642:Bicycling / Q000502:physiology*; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D011446:Prospective Studies; D019265:Spectroscopy, Near-Infrared