The findings of this one suggest that muscle fatigue per se cannot explain the loss of work efficiency during constant-load exercise above the gas exchange threshold (~50%-60% of VO2max), but muscle activation heterogeneity and metabolism can partially account for both.
- No temporal relationship between loss of work efficiency and the behaviour of muscle force production was observed.
- Loss of torque production, changes in the ratio between muscle V˙O2 kinetics and O2 delivery, a greater rating of perceived exertion, and the loss of work efficiency --mainly during very heavy exercise-- appear to share physiological mechanisms of similar origin.
- The work efficiency loss is bigger in the very heavy domain, and the changed anaerobic energy production is involved with the loss of work efficiency and muscle fatigue.
- The activation and recruitment of type I and II motor units, mainly in the rectus femoris muscle during cycling, could partially explain the additional O2 cost and muscle fatigue.
- The relationship of muscle fatigue and the work efficiency loss with the muscle fibre conduction velocity of different muscles is dependent on muscle activation heterogeneity during cycling.
- A positive, moderate, relationship between work efficiency loss and blood lactate accumulation was also found.
" the theory of Korzeniewski and Rossiter... stated that inorganic phosphate is the major contributor to the V˙O2sc (loss of work efficiency) and, the additional ATP usage indeed starts when cytosolic inorganic phosphate exceeds a ‘critical’ concentration...
"...Another study from the same authors indicated that the mechanisms of each-step activation of oxidative phosphorylation and inhibition of ATP supply by anaerobic glycolysis are associated with the V˙O2sc...these results partially confirm the theory stated above."
TL;DR, in english:
- Muscle fatigue and O2 cost seem to share the same physiological cause, linked with a decrease in muscle V˙O2 and a change in lactate accumulation.
- Muscle fatigue and work efficiency loss are associated with muscle activation heterogeneity and metabolism of different muscles activated during exercise.
Energy metabolism and muscle activation heterogeneity explain V˙O2 slow component and muscle fatigue of cycling at different intensities (open access)
doi.org/10.1113/EP0904…
#exercise #Workout #TrainHard #GymLife #GymTime #muscle #strength #lift #GetStrong #cardio #hiit
doi.org/10.1113/EP0904…
#exercise #Workout #TrainHard #GymLife #GymTime #muscle #strength #lift #GetStrong #cardio #hiit
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