Physiological and Perceptual Responses to High-Intensity Circuit Training using Body Weight as Resistance: Are There Sex-Specific Differences?

High-intensity circuit training (HICT) using body weight as resistance is a popular fitness trend and an ideal exercise modality in terms of functionality and economy. Given the popularity of HICT, evidence suggests that sex may elicit unique physiological and perceptual responses to this mode of exercise and there is a need for further work in this area. The purpose of this study was to examine physiological and perceptual responses of females and males to HICT using body weight resistance exercise. Forty-five participants (23 females and 22 males) completed baseline testing and a 15-minute HICT exercise bout wearing a portable metabolic analyzer. %VO(2max), %HR(max), and RER were monitored during exercise and analyzed at 3 different 5-minute time segments during the HICT (beginning, middle, end). RPE was assessed half-way through the circuit (7.5), immediately upon cessation of exercise (15), and 15-minutes post-exercise (Session RPE). There was a significant (p<0.01) time effect on %VO(2max), %HR(max), RER, and RPE. At all three time points, %VO(2max) was significantly (p<0.02) higher among females compared to males. RER values were significantly (p=0.02) higher among females during the last 5-minute segment (i.e. the end) of the exercise bout. However there were no differences in %HR(max) (p>0.20). Males reported a higher RPE immediately post-exercise compared to females (p=0.01). Taken together, these data suggest that there are distinct, sex-specific physiological and perceptual responses to HICT; thus, sex-specific exercise prescription considerations are warranted.