Exercising with reserve: Evidence that the CNS regulates exercise performance

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The below may be of interest:

Exercising with reserve: Evidence that the CNS regulates prolonged

exercise performance

Jeroen Swart 1*, Lamberts 1, Ian Lambert 1,

Alan St Clair Gibson 2, Estelle Vicki Lambert 2, Skowno 3 and

Noakes 3

Objective: The purpose of this study was to measure the effects of an

amphetamine (methylphenidate) on exercise performance at a fixed

rating of perceived exertion of 16.

Methods: Eight elite cyclists ingested 10mg Methylphenidate in a

randomized, placebo-controlled cross-over trial.

Results: Compared to placebo, subjects receiving methylphenidate

cycled for ~ 32% longer before power output fell to 70% of the

starting value. At the equivalent time at which the placebo trial

terminated, subjects receiving methylphenidate had significantly

higher power outputs, oxygen consumptions, heart rates, ventilatory

volumes and blood lactate concentrations although EMG activity

remained unchanged. Thus the ingestion of a centrally-acting

stimulant allowed subjects to exercise for longer at higher cardio-

respiratory and metabolic stress indicating the presence of a

muscular reserve in the natural state.

Conclusions: This suggests that endurance performance is not

only " limited " by mechanical failure of the exercising muscles

( " peripheral fatigue " ). Rather performance during prolonged endurance

exercise under normal conditions is highly regulated by the CNS to

insure that whole body homeostasis is protected and an emergency

reserve is always present.

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Carruthers

Wakefield, UK