Low-volume, high-intensity, aerobic interval exercise for sedentary adults: O2max, cardiac mass, and heart rate recovery

The aim of this study was to compare the effects of low-volume, high-intensity aerobic interval training (HAIT) on maximal oxygen consumption (O-2max), left ventricular (LV) mass, and heart rate recovery (HRR) with high-volume, moderate-intensity continuous aerobic training (CAT) in sedentary adults. Twenty-four healthy but sedentary male adults (aged 29.2 +/- A 7.2 years) participated in an 8-week, 3-day a week, supervised exercise intervention. They were randomly assigned to either HAIT (18 min, 180 kcal per exercise session) or CAT (45 min, 360 kcal). O-2max, LV mass (3T-MRI), and HRR at 1 min (HRR-1) and 2 min (HRR-2) after maximal exercise were measured pre- and post-intervention. Changes in O-2max during the 8-week intervention were significant (P < 0.01) in both groups (HAIT, 8.7 +/- A 3.2 ml kg(-1) min(-1), 22.4 +/- A 8.9 %; CAT, 5.5 +/- A 2.8 ml kg(-1) min(-1), 14.7 +/- A 9.5 %), while the O-2max improvement in HAIT was greater (P = 0.02) than in CAT. LV mass in HAIT increased (5.1 +/- A 8.4 g, 5.7 +/- A 9.1 %, P = 0.05), but not in CAT (0.9 +/- A 7.8 g, 1.1 +/- A 8.4 %, P = 0.71). While changes in HRR-1 were not significant in either group, change in HRR-2 for HAIT (9.5 +/- A 6.4 bpm, 19.0 +/- A 16.0 %, P < 0.01) was greater (P = 0.03) than for CAT (1.6 +/- A 10.9 bpm, 3.9 +/- A 16.2 %, P = 0.42). This study suggests that HAIT has potential as a time-efficient training mode to improve cardiorespiratory capacity and autonomic nervous system function in sedentary adults.