Effects of a Low-Volume Aerobic-Type Interval Exercise on VO2max and Cardiac Mass

Purpose The aim of this study was to compare the effects of time-efficient, low-volume interval exercises on cardiorespiratory capacity and left ventricular (LV) mass with traditional continuous exercise in sedentary adults. Methods Forty-two healthy but sedentary male subjects (age 26.5 +/- 6.2 yr) participated in an 8-wk, five times per week, supervised exercise intervention. They were randomly assigned to one of three exercise protocols: sprint interval training (SIT, 5 min, 100 kcal), high-intensity interval aerobic training (HIAT, 13 min, 180 kcal), and continuous aerobic training (CAT, 40 min, 360 kcal). Cardiorespiratory capacity (VO2max) and LV mass (3T-MRI) were measured preintervention and postintervention. Results We observed significant (P < 0.01) increases in VO2max in all three groups, and the effect of the HIAT was the greatest of the three (SIT, 16.7% +/- 11.6%; HIAT, 22.5% +/- 12.2%; CAT, 10.0% +/- 8.9%; P = 0.01). There were significant changes in LV mass, stroke volume (SV), and resting HR in both the SIT (LV mass, 6.5% +/- 8.3%; SV, 5.3% +/- 8.3%; HR, -7.3% +/- 11.1%; all P < 0.05) and HIAT (LV mass, 8.0% +/- 8.3%; SV, 12.1% +/- 9.8%; HR, -12.7% +/- 12.2%; all P < 0.01) but not in the CAT (LV mass, 2.5% +/- 10.1%; SV, 3.6% +/- 6.6%; HR, -2.2% +/- 13.3%; all P > 0.05). Conclusions Our study revealed that VO2max improvement with the HIAT was greater than with the CAT despite the HIAT being performed with a far lower volume and in far less time than the CAT. This suggests that the HIAT has potential as a time-efficient training mode to improve VO2max in sedentary adults.