Modified sprint interval training protocols: Physiological and psychological responses to four weeks of training

Sprint interval training (SIT) protocols involving brief (≤15 s) work bouts improve aerobic and anaerobic performance, highlighting peak speed generation as a potentially important adaptive stimulus. To determine the physiological and psychological effects of reducing the SIT work bout duration, while maintaining total exercise and recovery time, forty-three healthy males (n=27) and females (n=16) trained for four weeks (three times/week) using one of the following running SIT protocols: 1) 30:240 (n=11; 4-6 x 30 s bouts, 4 min rest); 2) 15:120 (n=11; 8-12 x 15 s bouts, 2 min rest); 3) 5:40 (n=12; 24-36 x 5 s bouts, 40 s rest); or 4) served as a non-exercising control (CTRL, n=9). Protocols were matched for total work (2-3 min) and rest (16-24 min) duration, as well as the work-to-rest ratio (1:8 s). Pre- and post-training measures included a: graded VO2max test, 5-km time trial, and 30 s maximal sprint test. Self-efficacy, enjoyment, and intentions were assessed following the last training session. Train...