Energy-Matched Endurance and Resistance Training Elicit Distinct Adaptations in VO ₂ Peak and Time to Exhaustion in Postmenopausal Women with Obesity and Prediabetes

Objective: This study examined whether 12 weeks of energy-matched endurance training (ET) or resistance training (RT) differentially affect maximal oxygen uptake (VO 2 Peak) and time to exhaustion (TTE) in sedentary postmenopausal women with obesity and prediabetes, and whether changes in aerobic capacity are accompanied by changes in exercise tolerance. Hypothesis: We hypothesized that endurance training would result in greater improvements in VO 2 Peak and time to exhaustion compared to resistance training. Methods: PM women with prediabetes and obesity participating in an ongoing larger study of fat metabolism participated. Participants were randomized to 12 weeks of ET (n = 14; mean ± SD: age 60 ± 5 yr; BMI 35.9 ± 4.75 kg·m - 2 ) or RT (n = 23; mean ± SD: age 61 ± 5 yr; BMI 35.8 ± 4.4 kg·m - 2 ). PM status was defined as cessation of menses for at least 2 years. All study outcomes were assessed before (PRE) and following (POST) 12 weeks of ET or RT. Two-way mixed repeated-measures ANOVA was used to examine effects of Time (PRE vs POST) and Group (ET vs RT) on VO 2 Peak and TTE. Within-group changes were also assessed using paired t-tests for descriptive purposes. Absolute change scores (ΔVO 2 Peak and ΔTTE) were calculated and used in secondary between-group comparisons and correlational analyses to explore metabolic–performance relationships. Results: Endurance training resulted in a significant increase in VO 2 Peak (mean Δ = +2.10 ml·kg - ¹·min - ¹; p = .032), whereas no significant change was observed following resistance training (p = .110); however, the magnitude of VO 2 Peak change did not differ between groups (p = .664). Repeated-measures ANOVA revealed a significant main effect of Time for VO 2 Peak (F 1 , 35 = 6.98, p = .012) with no significant Time × Group interaction (F 1 , 35 = 0.15, p = .705), indicating similar overall patterns of change across training modalities. In contrast, time to exhaustion significantly increased following resistance training (mean Δ = +1.86 min; p = .0025), while no significant change was observed following endurance training (p = .295); nonetheless, the magnitude of TTE change did not differ significantly between training modalities (p = .402). Repeated-measures ANOVA further demonstrated a significant main effect of Time for TTE (F 1 , 35 = 8.53, p = .006) with no significant Time × Group interaction (F 1 , 35 = 1.13, p = .294), and no overall Group effect (F 1 , 35 = 0.19, p = .667). Changes in VO 2 Peak were not associated with changes in time to exhaustion in either the endurance training group (r = 0.15, p = 0.620) or the resistance training group (r = 0.07, p = 0.743). Conclusion: Endurance training improved aerobic capacity without a corresponding improvement in time to exhaustion, whereas resistance training improved time to exhaustion without significantly increasing VO 2 Peak. However, the magnitude of adaptation did not differ between training modalities for either outcome. Changes in VO 2 Peak were not associated with changes in time to exhaustion in either group. These findings highlight a dissociation between changes in aerobic capacity and functional performance and suggest that short-term, energy-matched exercise interventions may elicit modality-specific adaptations that are not captured by VO 2 Peak alone in this metabolically vulnerable population. Grant or Funding information: NIH RO1 DK125728 This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.