Author(s): IGLESIAS-SOLER, E., NINE, I., RIAL-VÁZQUEZ, J., FARIÑAS, J., RÚA-ALONSO, M., CARNERO, E.A., Institution: PERFORMANCE AND HEALTH GROUP. UNIVERSITY OF A CORUNA. , Country: SPAIN, Abstract-ID: 1485

INTRODUCTION:
Hormonal changes associated with menopause affect several components of women’s health-related fitness, including body composition and cardiorespiratory and neuromuscular function. Resistance training is an effective strategy to mitigate some deleterious menopausal effects. Among resistance training variables, set configuration has been shown to modulate metabolic, cardiovascular, and mechanical responses. Moreover, metabolic adaptation (i.e., measured resting metabolic rate that is lower than the predicted value) has been observed after combined endurance and resistance training in older women. This study aimed to analyze the effects of resistance training programs with different set configurations on body composition, resting metabolic rate (RMR), and metabolic adaptation in physically active postmenopausal women.
METHODS:
Thirty-two physically active postmenopausal women (64 ± 10 years) participated. At baseline, RMR and body composition were assessed after an overnight fast. VO₂ and VCO₂ were measured for 45 minutes using open-circuit indirect calorimetry (CORTEX Metamax 3B-R2), and RMR was calculated from the final 20 minutes of steady-state data. Body composition was evaluated by multifrequency tetrapolar bioelectrical impedance (Bodystat 4000 QuadScan). Stepwise regression was used to estimate resting energy expenditure from fat-free mass (FFM) and fat mass (FM), with only FFM retained. A subsample of 23 participants subsequently completed a 12-week resistance training program and were assigned to either a short (9 sets of 4 repetitions at 12RM) or long (4 sets of 9 repetitions at 12RM) set configuration. Programs were equated for work-to-rest ratio. In this subsample, body composition and RMR were reassessed post-intervention. Metabolic adaptation was determined by comparing measured post-training RMR with estimated baseline RMR. Linear mixed models and paired t-tests were used.
RESULTS:
In the training subsample, FFM significantly increased (1.1 ± 0.4 kg; p = 0.011), with no between-group differences. FM decreased in both groups, with a trend for time (−0.9 ± 0.4 kg; p = 0.06). RMR remained unchanged after training (1581 vs. 1558 kcal/day). No differences were found between estimated and measured post-training RMR (p = 0.365).
CONCLUSION:
Set configuration did not modulate body composition changes in physically active postmenopausal women. In the training subsample, both interventions improved body composition, mainly by increasing FFM. This increase was not accompanied by changes in RMR, potentially suggesting adaptive thermogenesis. However, no differences were observed between estimated and measured RMR post-intervention. Thus, unlike combined training, resistance training alone does not seem to induce metabolic adaptation, regardless of set configuration.