Oxygen uptake during repeated-sprint exercise

Abstract

Objectives

Repeated-sprint ability appears to be influenced by oxidative metabolism, with reductions in fatigue and improved sprint times related to markers of aerobic fitness. The aim of the current study was to measure the oxygen uptake $(\dot{\text{V}}{\text{O}}_2)$ during the first and last sprints during two, 5 × 6-s repeated-sprint bouts.

Design

Cross-sectional study.

Methods

Eight female soccer players performed two, consecutive, 5 × 6-s maximal sprint bouts (B1 and B2) on five separate occasions, in order to identify the minimum time (t_rec) required to recover total work done (W_tot) in B1. On a sixth occasion, expired air was collected during the first and last sprint of B1 and B2, which were separated by t_rec.

Results

The t_rec was 10.9 ± 1.1 min. The $\dot{\text{V}}{\text{O}}_2$ during the first sprint was significantly less than the last sprint in each bout (p < 0.001), and the estimated aerobic contribution to the final sprint (measured in kJ) was significantly related to $\dot{\text{V}}{\text{O}}_2\max$ in both B1 (r = 0.81, p = 0.015) and B2 (r = 0.93, p = 0.001). In addition, the $\dot{\text{V}}{\text{O}}_2$ attained in the final sprint was not significantly different from $\dot{\text{V}}{\text{O}}_2\max$ in B1 (p = 0.284) or B2 (p = 0.448).

Conclusions

The current study shows that the $\dot{\text{V}}{\text{O}}_2$ increases from the first to the last of 5 × 6-s sprints and that $\dot{\text{V}}{\text{O}}_2\max$ may be a limiting factor to performance in latter sprints. Increasing $\dot{\text{V}}{\text{O}}_2\max$ in team-sport athletes may enable increased aerobic energy delivery, and consequently work done, during a bout of repeated sprints.

Introduction

Intense physical efforts performed at maximal or near-maximal speeds are important determinants of successful team-sport performance, with more fast-paced running and sprinting completed by top-level soccer players (both male and female) compared with their lower-level counterparts.1, 2 However, the volume of high-intensity running (measured by distance covered) has been shown to decline over the course of a soccer match, irrespective of playing standard.¹ These findings reflect fatigue development and suggest that the ability to recover from high-intensity running and sprinting may be an important marker of successful physical performance within team sports. It has also been suggested that fatigue development following high-intensity bursts has a detrimental effect on technical performance, and that technical success may be related to the ability to recover.³

Various markers of aerobic fitness, including maximal oxygen uptake ($\dot{\text{V}}{\text{O}}_2\max$), velocity at $\dot{\text{V}}{\text{O}}_2\max$ ($\text{v-}\dot{\text{V}}{\text{O}}_2\max$), velocity at the onset of blood lactate accumulation (v-OBLA) and $\dot{\text{V}}{\text{O}}_2$ kinetics, have been related to a reduction in fatigue (i.e., a smaller decrement in performance) over the course of a repeated-sprint bout.4, 5, 6 As well as performance decrement, other parameters associated with repeated-sprint ability (RSA) have been related to markers of aerobic fitness. For example, da Silva et al.⁶ found both v-OBLA and $\text{v-}\dot{\text{V}}{\text{O}}_2\max$ to be negatively correlated with the mean time to complete 7 × 34.2-m sprints. In addition, Dupont et al.⁵ reported a positive correlation between the time constant for the fast component of $\dot{\text{V}}{\text{O}}_2$ kinetics and the total time to complete 15 × 40-m sprints. Therefore, it appears that RSA is at least partially influenced by oxidative metabolism, perhaps via improved PCr resynthesis between sprints and greater aerobic contributions to latter sprints.7, 8 Despite these relationships, the $\dot{\text{V}}{\text{O}}_2$ during isolated maximal sprints has not been investigated during repeated-sprint exercise.

The majority of studies reporting aerobic contributions to maximal exercise have used single sprints lasting more than 10 s, with reported estimates for 90-, 60-, 45- and 30-s sprints of 61–64%, 49%, 31% and 23–28%, respectively.9, 10 These data demonstrate a linear decrease in aerobic contribution as sprint time decreases and, using these values, the predicted aerobic contribution to a 6-s sprint would be ∼9%. Péronnet and Thibault¹¹ calculated a value slightly lower than this estimate, suggesting a 5% aerobic contribution to a single 6-s sprint. However, this 5% value was derived from a mathematical model of metabolic energy production for the 1987 men's 60-m world record, rather than measured directly. Relatively few studies have attempted to unravel the complex energy contributions to repeated sprints lasting <10 s. Gaitanos et al.¹² showed a 65% decrease in anaerobic ATP production from the first to the last of 10 × 6-s sprints separated by 30 s. Since the associated performance decline was much smaller (27%), the authors hypothesised an increased aerobic energy contribution to the latter sprints. However, this was not measured directly and the hypothesis does not appear to have been tested to date.

The aim of the current study was to measure the $\dot{\text{V}}{\text{O}}_2$ and estimate the aerobic contribution during the first and last sprints of two, 5 × 6-s repeated-sprint bouts. It was hypothesised that (i) the $\dot{\text{V}}{\text{O}}_2$ and estimated aerobic contribution would be greater during the final sprint versus the first sprint of each respective bout and (ii) the estimated aerobic contribution to the final sprint of each bout would be related to $\dot{\text{V}}{\text{O}}_2\max$.