Sex Differences in Cardiac Adaptation to Distinct Modalities of Exercise: A Cardiac Magnetic Resonance Study

Purpose: No previous study has described sex differences in chronic cardiac adaptation in response to distinct modalities of exercise training in humans. Methods: Cardiac magnetic resonance imaging (1.5 T) was used to assess left ventricular (LV) outcomes in 78 untrained subjects (46F, 26 M; 26.1 +/- 5.4 yr). Subjects underwent 3 months of closely supervised and monitored resistance (RES) and endurance (END) training, separated by a 3-month washout period. Results: LV mass (LVM) increased in response to END in both sexes (females Delta 3.98 +/- 7.98 g, P = 0.002; males Delta 5.99 +/- 10.67 g, P = 0.005), whereas LV end-diastolic volume (EDV) increased inmales (Delta 7.48 +/- 11.91mL, P = 0.002) but not females (Delta 1.54 +/- 10.49 mL, P = 0.373). In response to RES, LVM and EDV did not increase in either sex. The proportion of subjects exhibiting a positive response to training (i.e., a change >0) for LVM and EDV did not differ between sexes for either training modality. Conclusion: Eccentric hypertrophy in response to END training was more apparent in males than females, whereas there were no notable cardiac changes between sexes for RES training. The proportion of low versus high responders to training was not sex specific for LVM or EDV in response to either commonly prescribed exercise training modality.