Sex Differences in High-Intensity Interval Training–Are HIIT Protocols Interchangeable Between Females and Males?

Abstract

Background: High-intensity interval training (HIIT) is a well-established training modality to improve aerobic and anaerobic capacity. However, sex-specific aspects of different HIIT protocols are incompletely understood. This study aimed to compare two HIIT protocols with different recovery periods in moderately trained females and males and to investigate whether sex affects high-intensity running speed and speed decrement. Methods: Fifty moderately trained participants (30 females and 20 males) performed an exercise field test and were randomized by lactate threshold (LT) to one of two time-and workload-matched training groups. Participants performed a 4-week HIIT intervention with two exercise sessions/week: Group 1 (4 × 30,180 HIIT), 30-s all-out runs, 180-s active recovery and Group 2 (4 × 30,30 HIIT), 30-s all-out runs, 30-s active recovery. High-intensity runs were recorded, and speed per running bout, average speed per session, and speed decrement were determined. Blood lactate measurements were performed at baseline and follow-up at rest and immediately post-exercise. Results: Females and males differed in running speed at LT and maximal running speed determined during exercise field test (speed at LT, females: 10.65 ± 0.84 km h −1 , males: 12.41 ± 0.98 km h −1 , p < 0.0001; maximal speed, females: 14.55 ± 1.05 km h −1 , males: 17.41 ± 0.68 km h −1 , p < 0.0001). Estimated maximal oxygen uptake was ~52.5 ml kg −1 min −1 for females and 62.6 ml kg −1 min −1 for males (p < 0.0001). Analysis of HIIT protocols revealed an effect of sex on change in speed decrement (baseline vs. follow-up) in that females showed significant improvements only in the 4 × 30:30 HIIT group (p = 0.0038). Moreover, females performing the 4 × 30:30 protocol presented increased speed per bout and average speed per session at follow-up (all p ≤ 0.0204), while no effect was detected for females performing the 4 × 30:180 protocol. Peak blood lactate levels increased in all HIIT groups (all p < 0.05, baseline vs. follow-up), but males performing the 4 × 30:180 protocol showed no difference in lactate levels. Conclusions: If not matched for physical performance, females, but not males, performing a 4 × 30 HIIT protocol with shorter recovery periods (30 s) present increased average Schmitz et al.

Effects of 4 Weeks of a Technique-Specific Protocol with High-Intensity Intervals on General and Specific Physical Fitness in Taekwondo Athletes: An Inter-Individual Analysis

“…In this sense, although the HIIT all-out format is accepted in the scientific literature, taekwondo athletes may have underestimated the intensity of the work performed; (ii) the lack of control of dietary habits that could have influenced the reported changes in body composition; (iii) the lack of progression of the training load applied in HIIT; (iv) the evaluation by bioimpedance, which could have overestimated the body composition; and (v) the small number of athletes analysed. In addition, potential biases that could have influenced the results of this study include the following: (i) the variability of the response according to the sex of the athletes [ 49 , 50 , 51 ]; (ii) the absence of analysis and subsequent distribution of the athletes according to their biological age [ 52 , 53 ]; (iii) the variation of physical performance according to the time of day [ 54 ]; and (vi) the possible variability of the body composition due to the use of bioimpedance [ 55 ].…”

Physiological sex differences affect the integrative response to exercise: acute and chronic implications

“…It is possible that females require less rest between intense interval exertions for adequate metabolic recovery; if standard training recommendations that are based predominately on male research are applied to both sexes, females might not receive an optimal stimulus for adaptation. Indeed, a recent study investigated whether manipulation of the rest period duration affects the adaptation to an interval training programme in males and females (Schmitz et al., 2020). The authors demonstrated a reduced training effect in female participants when rest periods were extended from 30 to 180 s, with no such effect in males.…”

Recovery from Different High-Intensity Interval Training Protocols: Comparing Well-Trained Women and Men

“…HIIT protocols from studies only performed with men are commonly adapted for women. This might be erroneous as the present results and previous studies have indicated that sex-dependent and anthropometric and physiological differences between females and males might significantly affect recovery following repeated high-intensity exercise and thus can affect training response [ 36 , 37 ]. During repeated bouts of exercise women, may be more resistant to fatigue and have a greater ability to recover metabolically, but they have slower heart rates and subjective recovery.…”