Acute Effects of Long Interval Training With Varied Recovery Periods in Trained Runners

The aim of this study was to assess the effect of recovery period during long interval training (IT) on mechanical, physiological, perceptive, and neuromuscular parameters. Six men and six women trained runners (23.82 ± 7.83years; 56.27 ± 8.95kg; 167.55 ± 9.77cm) performed three treadmill interval sessions (4x4min) at 1% incline with 1min, 2min or self-selected recovery periods (SSrecovery) at highest possible average running speed. Velocity and distance increased by 2.5% (p < 0.05) in SSrecovery (~ 190s) compared to 2min. Blood lactate concentration (BLC) (p < 0.01) and RPE (p < 0.05) were lower with SSrecovery compared to 1min. Vertical oscillation decrease in SSrecovery vs 1min (p < 0.01) and stride frequency in lower recovery periods compared to SSrecovery (p < 0.01). Women displayed lower stride length, distance, velocity, heart rate recovery (p < 0.001) and flight time (p < 0.05), and higher contact times, BLC and RPE (p < 0.05), and less CMJ height loss (p < 0.05) than men in all conditions. Our findings suggest that manipulating the duration of the recovery period during a 4x4min IT leads to a 5% decrease in performance in the shorter recovery periods, greater BLC and RPE combined with a lower stride frequency and higher vertical oscillation. Women had higher metabolic and perceptive stress than men, while men suffered more mechanical fatigue.