I02 Physiological, perceptual and neuromuscular responses to 15 vs. 30 s work durations during short high intensity interval training

Abstract

High intensity interval training (HIIT) is an extremely potent stimulus for physiological adaptation offering a low volume training approach that can be easily accommodated into an individual’s training schedule. A key feature that drives physiological adaptation is the time the individual spends at or around their individual V̇O_2max during HIIT. This can be influenced by several variables, including the work bout duration (Buchheit & Laursen, 2013, Sports Med, 43, 318-338). The use of short duration HIIT intervals (i.e., < 60 s) are popular due to their ability to facilitate a high oxygen uptake while minimising fatigue (Buchheit & Laursen, 2013, Sports Med, 43, 318-338). However, the physiological response to different short duration HIIT formats has not yet been investigated. The aim of this study was to measure the physiological, perceptual and neuromuscular responses to two traditional short duration (i.e., 15 and 30 s) HIIT formats in trained athletes. With ethics approval, 10 well-trained male and female team sport players (mean + SD; age: 22 ± 1 years; body mass: 78 ± 6 kg; stature: 176 ± 4 cm) were recruited to the study and visited the laboratory on three separate occasions. After an incremental test to exhaustion on a cycle ergometer to establish V̇O_2max (52.3 ± 5.7 ml·kg^-1·min^-1) and peak power output at V̇O_2max (pV̇O_2max; 313 ± 21 W), two HIIT sessions (15 s effort: 15 s passive recovery and 30 s effort: 30 s passive recovery) were completed in a randomised order. HIIT interventions comprised 15 s or 30 s at 120% pV̇O_2max followed by 15 or 30 s passive recovery, repeated for 2 × 6 min with 5 min active recovery at 40% pV̇O_2max. V̇O₂, time >90% V̇O_2max, heart rate, and RPE were measured during the HIIT session and blood lactate concentration recorded 5 minutes afterwards. Measures of knee extensor maximal voluntary contraction (MVC) were measured immediately before and after each HIIT session.