Sex-related differences in the acute physiological response to a high-intensity CrossFit® workout

CrossFit® is popular form of fitness training but the cardiorespiratory, hemodynamic and metabolic responses have not been well characterised. We compared responses to a short Fran CrossFit® session (consisting of three rounds of 21, 15 and 9 front squat to press overhead and pull-ups) between sexes to evaluate differences in acute exercise effects. Twenty-five (15 males and 10 females) trained participants performed a prescribed Fran session at maximal exertion. Cardiorespiratory variables were assessed at baseline, during and post-exercise. The rating of perceived exertion, blood pressure, blood lactate and glucose concentrations were measured at baseline and in the recovery period. The males completed Fran session in less time (males 177 ± 15 vs females 206 ± 27 s; mean ±SD), resulting in higher peak oxygen uptake values (50.1 ± 3.3 vs 46.4 ± 2.2 mL·kg −1 ·min −1 ), heart rate (187 ± 6 vs 180 ± 3 b∙min -1 ) and percentage heart rate (96 ± 3 vs 93 ± 1%) compared to females. In addition, elevated systolic blood pressure (male 154 ± 8 vs females 149 ± 10 mmHg), double product (27,050 ± 1,504 vs 25,999 ± 2,253 mmHg·b∙min –1 ), blood lactate (15.7 ± 1.7 vs 14.6 ± 2.0 mmol∙L –1 ) and glucose (132 ± 15 vs 132 ± 14 mg∙dL –1 ) values were observed in both sexes post-exercise. The substantial metabolic demands associated with a Fran session can yield similar elevations in cardiorespiratory and hemodynamic responses in both sexes, meeting the criteria for developing cardiorespiratory fitness. Complementarily, these results suggest that researchers and coaches can use the Fran session at maximal effort to assess and monitor crossfitters' training status throughout a CrossFit® season, guiding efforts towards excellence in this demanding sport. • Male participants demonstrated higher peak oxygen consumption and heart rate values and completed the Fran session in less time than female participants. • Although blood lactate, glucose, and blood pressure responses after exercise were similar between sexes, ventilatory and performance responses differed. • These sex-based physiological differences highlight the need for individualized CrossFit® programming and recovery strategies. • The Fran workout elicited cardiovascular responses consistent with vigorous-intensity exercise and can be used to monitor training status over time.