Abstract
To study the physiologic basis of variability of physical performance in the laboratory,
ten male subjects were studied once a week, during a 9-12 month period. Previously,
the reference maximal work load attained (Wref) was determined in each subject. The
test protocol of the actual study was based on the individual Wref and started at
70% Wref for 5 min whereupon the work load was increased by 5% Wref every 2.5 min
to exhaustion. The maximal work load attained (Wmax) was considered as the test performance.
Heart rate, respiratory variables, oxygen uptake (V̇O2), and blood lactate concentration were determined at each work load. The rate of
perceived exertion during submaximal and maximal work was also scored. In all subjects,
Wmax and V̇O2max varied randomly, while the coefficient of variation in V̇O2max (4.20%-11.35%) exceeded that in Wmax (2.95%-6.83%). No seasonal influences on
V̇O2max and Wmax were observed. In all subjects the physiologic variables, when plotted
as a function of external work load, were shifted to the right with higher Wmax values
and to the left with lower Wmax values. With lower Wmax values, the rate of perceived
exertion during submaximal work tended to increase. The results suggest that the magnitude
of physiologic responses to exercise is related to relative work load and that variability
of physical performance is related to changes in gross mechanical efficiency.
Key words
exercise - performance - variability - aerobic power - rate of perceived exertion
