The effect of decreased muscle energy stores on thekinetics at the onset of exercisekinetics at the onset of exercise

Autor: Paganelli, W., Pendergast, D. R., Koness, J., Cerretelli, P.
Zdroj: European Journal of Applied Physiology and Occupational Physiology; December 1989, Vol. 59 Issue: 5 p321-326, 6p
Abstrakt: The kinetics of adjustment of oxygen uptakeat the onset of a square wave of exercise in man has been shown to be variable and related mainly to factors located distal to the capillary. The present study examined the effects of decreasing oxygen and high energy phosphates (∼P) stores, by blood flow occlusion (BFO) and/or preceding exercise, on the half time of theon-response (on-) during arm exercise. Twelve male subjects performed an arm exercise test at a standard intensity of 75 W (75 WA) following six procedures designed progressively to decrease O2and/or ∼P stores. Breath-by-breathand lactic acid accumulation in blood (Δ[lab]) during thetransient were measured. Preceding the 75 WAby 5 min of 125 W leg exercise decreased significantly theon- (63–47 s). Preceding the 75 WAwith either arm BFO and isometric exercise (1 min), no-load or 25 W (25 WA) arm cranking (5 min) did not significantly affecton- or Δ[lab]. Preceding 75 WAwith 5–10 min BFO or BFO plus 25 WAresulted in a significant decrease inon- (20% and 50%, respectively). The Δ[lab] increased linearly withon-responses greater than 24 s. These data suggest that the local depletion of O2and/or ∼P stores play an important role in determining the kinetics of adjustment ofto exercise.
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