Faster adjustment of O2 uptake to the energy requirement of exercise in the trained state.

The purpose of this study was to determine the effect of endurance exercise training on the time course of the increase in VO2 toward steady state in response to submaximal constant load work. Seven men participated in a strenuous program of endurance exercise for 40 min/day, 6 days/wk for 10 wk. Their average VO2max increased from 3.29 liters before training to 4.53 liters at the end of the training program. VO2 was measured continuously on a breath-by-breath basis at work rates requiring 40%, 50%, 60%, or 70% of VO2max before training. After training the subjects were retested both at the same absolute and the same relative work rates. The increases in VO2 toward steady state occurred more rapidly in the trained than in the untrained state both at the same absolute and at the same relative work rates. The finding that O2 uptake rises to meet O2 demand more rapidly in the trained than in the untrained state provides evidence that the working muscles become less hypoxic at the onset of exercise of the same intensity after training.

Linear increase in aerobic power induced by a strenuous program of endurance exercise.

Eight subjects exercised for 40 min/day, 6 days/wk for 10 wk. For 3 days/wk they performed six 5-min intervals of bicycling on an ergometer against a resistance that elicited VO2 max, separated by 2-min intervals of exercise requiring 50-60% of Vo2 max. On the alternate 3 days, they ran as far as they could in 40 min. Our purpose was to obtain information regarding the time course and magnitude of the increase in Vo2 max and endurance that occur in response to strenuous exercise when the training stimulus is kept approximately constant relative to maximum aerobic capacity. Average Vo2 max increased 5% (P less than 0.05) during the 1st wk. Endurance, Vo2 max, and time to attainment of peak heart rate all increased linearly during the 10 wk. The average weekly increase in Vo2 max was 0.12 l/min. The total increase in Vo2 max averaged 16.8 ml/kg per min (44%). Four of the eight subjects attained Vo2 max levels approaching or exceeding 60 ml/kg per min. It appears from these results that aerobic work capacity can increase more rapidly and to a greater extent in response to training than has generally been thought.

Correlation between gait speed and spasticity at the knee.

An automated system designed and developed at this laboratory was used to measure spasticity in the thigh musculature of fifteen patients with hemiplegia. In addition, each subject was timed during a gait trial over a measured distance at maximum speed. Analysis of the data revealed no statistically significant correlation between spasticity in the thigh musculature and the gait speed of the subjects studied. Factors which may have contributed to the findings are mentioned.