This study examined sex-specific responses during self-paced, high-intensity interval training (HIIT). Sixteen (8 male, 8 female) individuals completed a VO2peak test and 3 treadmill HIIT sessions on separate days. The HIIT sessions consisted of 6, 4 minute intervals performed at the highest self-selected intensity individuals felt they could maintain. Recovery between intervals were counterbalanced and consisted of 1-min, 2-min, or 4-min recovery during each trial. Relative measures of intensity including percent of velocity at VO2peak (vVO2peak), percent of VO2peak, percent of HRmax, and blood lactate concentration ([La]) were observed during the trials. Perceived readiness was recorded immediately before and ratings of perceived exertion (RPE) were recorded at the end of each interval with session RPE recorded after each trial. Results revealed a significant effect of sex on %vVO2peak (p<0.01) and %HRmax (p<0.01). Data show that across trials men self-select higher %vVO2peak (84.5% vs. 80.7%), whereas, women produce higher %HRmax (96.9% vs. 92.1%) and %VO2peak (89.6% vs. 86.1%) with no difference in [La] or perceptual responses. These findings support the notion that women may demonstrate improved recovery during high-intensity exercise, as they will self-select intensities resulting in greater cardiovascular strain. Moreover, results confirm previous findings suggesting a 2:1 work-to-rest ratio is optimal during HIIT for both men and women.
Copyright (C) 2013 by the National Strength & Conditioning Association.