This study compared the effects of a 2-week program of low-volume high-intensity interval training (HIT) with the effects of higher-volume moderate-intensity continuous training (CT) on cardiopulmonary and vascular functions in postmenopausal women.
Twenty-two postmenopausal women were randomly assigned to undertake six HIT (n = 12) or CT (n = 10) sessions for 2 weeks. HIT sessions consisted of ten 1-minute intervals of cycling exercise
at 100% of peak power output separated by 1 minute of active recovery. CT sessions involved 40 minutes of continuous cycling at 65% of peak power output. Variables assessed at baseline and 2 weeks included cardiopulmonary function (ventilatory threshold, peak oxygen uptake), macrovascular endothelial function
of the brachial artery), and microvascular function (reactive hyperemia and local thermal hyperemia of forearm skin).
Eighteen participants completed the study (HIT, 11; CT, 7). Adherence to the exercise
programs was excellent, with 107 of 108 sessions completed. Despite substantially lower total time commitment (∼2.5 vs ∼5 h) and training volume (558 vs 1,237 kJ) for HIT versus CT, increases from baseline in peak oxygen uptake achieved significance (P
= 0.01) for the HIT group only (Δ = 2.2 mL kg−1
for interaction = 0.688). Improvements in exercise
test duration were observed in both groups (HIT, 13%; CT, 5%; P
for interaction = 0.194). There were no significant changes in macrovascular or microvascular function in either group.
The findings suggest that low-volume HIT is feasible and can lead to rapid improvements in cardiopulmonary function in postmenopausal women.