Neuromuscular function during prolonged pedalling exercise at different cadences.
OBJECTIVE
The purpose of the present work was to assess the strategies set by the central nervous system in order to provide the power output required throughout a prolonged (1-h) pedalling exercise performed at different cadences (50 rpm, 110 rpm and the freely chosen cadence).


METHODS
Neuromuscular (NM) activity of vastus lateralis, rectus femoris, biceps femoris and gastrocnemius lateralis muscles was studied quantitatively [root-mean square (RMS) and mean power frequency (MPF)] and qualitatively (timing of onset and offset of muscle bursts during crank cycle).


RESULTS
The present results showed that increased cadence resulted in earlier muscle activation in crank cycle. The influence of cadence on RMS and MPF depended on the considered muscle and its functional role during pedalling. Timing of onset and offset of muscle bursts was not altered by fatigue throughout the prolonged exercise. In contrast, RMS and MPF of some muscles was found to increase during prolonged exercise.


CONCLUSIONS
In summary, the present study revealed that tonic aspects of the NM activity (RMS, MPF) are altered during prolonged pedalling exercise, while phasic aspects are remained unchanged. These results suggest that the strategies set by the central nervous system in order to provide the power output required by the exercise are held constant throughout the exercise, but that quantitative aspects of the central drive are increased in order to adapt to the progressive occurrence of the NM fatigue.
Sarre
G
G
INSERM ERM207, UFR STAPS, Université de Bourgogne, Dijon Cedex, France.
Lepers
R
R
D000222:Adaptation, Physiological; D000704:Analysis of Variance; D002490:Central Nervous System / Q000502:physiology*; D004576:Electromyography; D016552:Ergometry; D006801:Humans; D007717:Knee; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology*; D013997:Time Factors