Maximal-Intensity Intermittent Exercise: Effect of Recovery Duration

Abstract

Seven male subjects performed 15×40m sprints, on three occasions, with rest periods of either 120 s (R₁₂₀), 60 s (R₆₀) or 30 s (R₃₀) between each sprint. Sprint times were recorded with four photo cells placed at 0, 15, 30 and 40 m. The performance data indicated that whereas running speed over the last 10 m of each sprint decreased in all three protocols (after 11 sprints in R₁₂₀, 7 sprints in R₆₀ and 3 sprints in R₃₀), performance during the initial acceleration period from 0-15 m was only affected with the shortest rest periods increasing from (mean±SEM) 2.58±.03 (sprint 1) to 2.78±.04s (sprint 15) (p <.05). Post-exercise blood lactate concentration was not significantly different in R₁₂₀ (12.1±1.3mmol·l^-1) and R₆₀ (13.9±1.2mmol·l^-1), but a higher concentration was found in R₃₀ (17.2±.7mmol·l^-1) (p < .05). After 6 sprints there was no significant difference in blood lactate concentration with the different recovery durations, however, there were significant differences in sprint times at this point, suggesting that blood lactate is a poor predictor of performance during this type of exercise. Although the work bouts could be classified primarily as anaerobic exercise, oxygen uptake measured during rest periods increased to 52, 57 and 66% of maximum oxygen uptake in R₁₂₀, R₆₀ and R₃₀, respectively. Evidence of adenine nucleotide degradation was provided by plasma hypoxanthine and uric acid concentrations elevated post-exercise in all three protocols. Post-exercise uric acid concentration was not significantly affected by recovery duration. These data indicate that during repeated 40 m sprints, however, a longer intervening rest period allowed for baseline performance to be sustained during more trials the associated net loss to the total adenine nucleotide pool was not suppressed.

Key words

Repeated sprints - performance - blood lactate - hypoxanthine - uric acid