Abstract 4361819: Sex Differences in Response to Endurance Training

Background: Few studies have systematically evaluated whether adaptations to endurance training differ by sex. We assessed sex differences in cardiopulmonary, body composition, and metabolic adaptations among male and female sedentary adults following a 20-week endurance training program. Hypothesis: Male and female participants will demonstrate equal cardiovascular and metabolic adaptations in response to an identical dose of supervised endurance training. Methods: HERITAGE Family Study participants (56% female, mean age: 34 years) completed a supervised endurance training program, with cardiopulmonary exercise tests, body composition, and metabolic assessments performed at baseline (n=834) and after the training period (n=720). Two-sample t-tests were used to compare exercise responses among male and female participants. An external exercise training intervention study involving 149 individuals with abdominal adiposity (63% female, mean age: 52 years) was used for validation of training-related adaptations. Results: We observed sex differences in several (18/65) training-related adaptations in HERITAGE. Notably, while male participants exhibited higher VO2max at baseline (36 vs 27 ml/kg/min, p=5x10-49), female participants demonstrated greater improvements following the training intervention (+20 vs +16%, p=2x10-7). From a body composition and metabolic standpoint, male participants exhibited greater reductions in body fat percentage (-4 vs -2%, p=0.004) and visceral fat (-6 vs -2%, p=0.002), and a three-fold greater increase in insulin sensitivity (+17 vs +6%, p=0.009) compared to female participants. In the validation cohort, male participants also demonstrated greater training-related improvements in body mass index, waist circumference, and insulin/glucose responses to an oral glucose tolerance test. Conclusions: This study highlights important sex differences in adaptations to endurance training. Specifically, while female individuals demonstrated greater trainability in VO2max, male individuals exhibited larger improvements in body composition and glucose/insulin metabolism.