Work efficiency in repeated sets of sprint interval exercise in cyclists

BACKGROUND: While interval training is considered an effective modality for improving physical performance, there is a lack of data on the body's response to repeated sets of sprint exercise. The aim of this study was to assess changes in work efficiency during subsequent sets of sprint interval training in cyclists with different interval training experience. METHODS: The study involved 20 cyclists divided into two groups: those who had been performing interval training for at least one year (experienced [group E], N.=10) and those who had no experience with interval training (inexperienced [group IE], N.=10). All participants performed an interval training-based exercise test involving four sets of four 30-s repetitions of maximal ergometer cycling interspersed with 90 s of low-intensity recovery. Each set was followed by a period of active recovery (lasting 25-40 minutes). Work output, total oxygen uptake, work efficiency and post-exercise H+ concentration were collected in each set. RESULTS: Work output in group IE decreased by the second and third set (5% and 7.3%, respectively) while only in the fourth set (1.6%) in group E. Work efficiency in group E increased by 7.1%, 7.2%, and 5.1% in the second, third, and fourth set, respectively; total oxygen uptake decreased in the third set by 2.4%. H+ concentrations decreased in the second and subsequent sets in group IE whereas in the third and subsequent sets in group E. CONCLUSIONS: An improvement in work efficiency in subsequent sets of sprint interval training was found in cyclists with interval training experience.