Effect of sprint interval training on circulatory function during exercise in sedentary, overweight/obese women

Very high-intensity, low-volume, sprint interval training (SIT) increases muscle oxidative capacity and may increase maximal oxygen uptake ((V) over barO(2max)), but whether circulatory function is improved, and whether SIT is feasible in overweight/obese women is unknown. To examine the effects of SIT on (V) over barO(2max) and circulatory function in sedentary, overweight/ obese women. Twenty-eight women with BMI > 25 were randomly assigned to SIT or control (CON) groups. One week before pre-testing, subjects were familarized to (V) over barO(2max) testing and the workload that elicited 50% (V) over barO(2max) was calculated. Preand post-intervention, circulatory function was measured at 50% of the pre-intervention (V) over barO(2max), and a GXT was performed to determine (V) over barO(2max). During the intervention, SIT training was given for 3 days/ week for 4 weeks. Training consisted of 4-7, 30-s sprints on a stationary cycle (5% body mass as resistance) with 4 min active recovery between sprints. CON maintained baseline physical activity. Post-intervention, heart rate (HR) was significantly lower and stroke volume (SV) significantly higher in SIT (-8.1 and 11.4%, respectively; P < 0.05) during cycling at 50% <(V)over bar>O(2max); changes in CON were not significant (3 and -4%, respectively). Changes in cardiac output ((Q) over bar) and arteriovenous oxygen content difference [(a -v) O2 diff] were not significantly different for SIT or CON. The increase in (V) over barO(2max) by SIT was significantly greater than by CON (12 vs. -1%). Changes by SIT and CON in HRmax (-1 vs. -1%) were not significantly different. Four weeks of SIT improve circulatory function during submaximal exercise and increases (V) over barO(2max) in sedentary, overweight/ obese women.