Effects of prolonged cycle ergometer exercise on maximal muscle power and oxygen uptake in humans.
The mechanical power (Wtot, W.kg-1) developed during ten revolutions of all-out periods of cycle ergometer exercise (4-9 s) was measured every 5-6 min in six subjects from rest or from a baseline of constant aerobic exercise [50%-80% of maximal oxygen uptake (VO2max)] of 20-40 min duration. The oxygen uptake [VO2 (W.kg-1, 1 ml O2 = 20.9 J)] and venous blood lactate concentration ([la]b, mM) were also measured every 15 s and 2 min, respectively. During the first all-out period, Wtot decreased linearly with the intensity of the priming exercise (Wtot = 11.9-0.25.VO2). After the first all-out period (t greater than 5-6 min), and if the exercise intensity was less than 60% VO2max, Wtot, VO2 and [la]b remained constant until the end of the exercise. For exercise intensities greater than 60% VO2max, VO2 and [la]b showed continuous upward drifts and Wtot continued decreasing. Under these conditions, the rate of decrease of Wtot was linearly related to the rate of increase of VO2 [(dWtot/dt) (W.kg-1 x s-1) = 5.0 x 10(-5) -0.20.(VO2/dt) (W.kg-1 x s-1)] and this was linearly related to the rate of increase of [la]b [(dVO2/dt) (W.kg-1 x s-1) = 2.3 x 10(-4) + 5.9 x 10(-5).(d[la]b/dt) (mM.s-1)].(ABSTRACT TRUNCATED AT 250 WORDS)
Capelli
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C
Dipartimento di Scienze e Tecnologie Biomediche, Sezione di Fisiologia, Udine, Italy.
Antonutto
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G
Zamparo
P
P
Girardis
M
M
di Prampero
P E
PE
D000328:Adult; D000332:Aerobiosis; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005221:Fatigue / Q000378:metabolism; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007700:Kinetics; D007773:Lactates / Q000097:blood; D008297:Male; D009132:Muscles / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*
D007773:Lactates