Abstract P177: Resistance Training Improves Cardiorespiratory Fitness And Maximal Fat Oxidation Similarly To Aerobic Training, But Uniquely Decreases Visceral Adipose Tissue In Previously Sedentary Postmenopausal Women

Abstract

Introduction: Cardiovascular disease is the leading cause of death for women, and postmenopausal (PM) women are a particularly vulnerable population in terms of adverse cardiometabolic (CM) risk. Progressive aerobic exercise training (AT) is efficacious for improving CM risk factors such as cardiorespiratory fitness (CRF), body composition (e.g., relative body fat (BF%)), and metabolic flexibility. However, there are large clinical gaps regarding the efficacy of progressive resistance training (RT) to reduce CM risk in PM women. Hypothesis: We hypothesized that 16 weeks of RT would (a) improve CRF, (b) decrease body weight, BF%, and visceral adipose tissue (VAT) volume, and (c) improve metabolic flexibility (as evidenced by an increase in maximal fat oxidation (MFO) during exercise) in a manner similar to AT, but greater than habitual activity control (CON). Methods: Forty-eight PM women (aged 56 ± 5 years) were randomized into RT (n=18), AT (n=16), or CON (n=14) and completed the study per protocol. Women in the RT group performed 2 - 4 sets of 9 resistance exercises using all major muscle groups on 3 d·wk -1 at 50-70% of one repetition maximum. Women in the AT group walked or biked 5 d·wk -1 at 50-65% of heart rate reserve. Women in the CON group maintained habitual physical activity levels and dietary habits. All exercise was progressive in nature. Pre- and post-intervention, participants arrived to the laboratory following a 10-h fast, and had body weight and VAT assessed using a medical-grade bioelectrical device and BF% determined by dual-energy x-ray absorptiometry. CRF (relative VO 2 in mL/kg/min), exercising whole body MFO (g/min), and the intensity at which MFO occurred (Fat max , %CRF) were determined using indirect calorimetry during a graded exercise test to volitional exhaustion on a cycle ergometer. Two-way mixed factorial ANOVAs and follow-up Holm-Sidak-corrected comparisons were used for statistical analyses. Changes are reported as mean ± SE of difference. Results: CRF and MFO increased similarly in the RT (+4.2 ± 1.0 mL/kg/min and +0.17 ± 0.05 g/min) and AT (+4.9 ± 1.0 mL/kg/min and +0.19 ± 0.05 g/min) groups (all p holm ≤ 0.001), and these changes were greater than in the CON group (+0.4 ± 1.0 ml/kg/min and -0.06 ± 0.05 g/min). There was similar improvement in Fat max among groups from pre- to post-intervention (+2.4 ± 1.7%; p = 0.01). Despite no observed changes in bodyweight ( p = 0.25), BF% decreased similarly in the RT (-1.21 ± 0.3%) and AT (-0.9 ± 0.3%) groups (all p holm ≤ 0.03), and to a greater extent than in CON (-0.49 ± 0.4%). However, only RT decreased VAT (-0.40 ± 0.14 l; p = 0.02). Conclusions: Sixteen weeks of RT was similarly efficacious to AT for improving CRF, reducing BF%, and increasing MFO in previously sedentary PM women. Interestingly, we demonstrate that RT may provide a unique benefit in reducing VAT.