This study sought to determine the time course of training adaptations to two different sprint interval training programmes with the same sprint: rest ratio (1:8) but different sprint duration. Nine participants (M: 7; F: 2) were assigned to 15-second training group (15TG) consisting of 4-6 × 15-second sprints interspersed with 2-minute recovery, whereas eight participants (M: 5; F: 3) were assigned to 30-second training group (30TG) consisting of 4-6 × 30 second sprints interspersed with 4-minute recovery. Both groups performed their respective training twice per week over 9 weeks and changes in peak oxygen uptake (V˙O2peak) and time to exhaustion (TTE) were assessed every 3 weeks. Additional eight healthy active adults (M: 6; F: 2) completed the performance assessments 9 weeks apart without performing training (control group, CON). Following 9 weeks of training, both groups improved V˙O2peak (15TG: 12.1%; 30TG: 12.8%, P<.05) and TTE (15TG: 16.2%; 30TG: 12.8%, P<.01) to a similar extent. However, while both groups showed the greatest gains in V˙O2peak at 3 weeks (15TG: 16.6%; 30TG: 17.0%, P<.001), those in TTE were greatest at 9 weeks. CON did not change any of performance variables following 9 weeks. This study demonstrated that while the changes in cardiorespiratory function plateau within several weeks with sprint interval training, endurance capacity (TTE) is more sensitive to such training over a longer time frame in moderately-trained individuals. Furthermore, a 50% reduction in sprint duration does not diminish overall training adaptations over 9 weeks.
Keywords: endurance capacity; peak oxygen uptake; sprint-to-rest ratio; time course of training adaptations.
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