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We investigated the effectiveness of a resistance training (RT) protocol with lower volume and lower load in the body recomposition of postmenopausal women, and to determine whether changes in body recomposition induced by RT would be associated with changes in physical performance, independently of confounding factors. Participants were randomly assigned to one of three groups: I) Single set-high load (SSHL, n = 14, 1 set of 8 to 12 maximum repetitions), II) Single set-low load (SSLL, n = 15, 1 set of 25 to 30 maximum repetitions), and III) Multiple sets-high load (MSHL, n = 14, 3–6 sets of 8 to 12 maximum repetitions). The study extended over a duration of 27 weeks, encompassing 24 weeks of RT. We assessed body composition using dual-energy X-ray absorptiometry, physical performance using the Timed Up and Go and sit and stand tests, and muscle strength using the one-repetition maximum (1RM) test. We quantified body recomposition using a composite z score calculated as follows: (appendicular lean mass % delta z score) + (− 1 × fat mass delta % z score) / 2. Results showed significant improvements in physical performance (P < 0.001), significant reductions in visceral adipose tissue, total fat mass, and % fat (P = 0.003, P = 0.042, and P < 0.001, respectively), and increases in muscle mass and strength (P < 0.001), regardless of group assignment. Notably, the higher load groups (SSHL and MSHL) had significantly greater body recomposition compared to the lower load group (SSLL), particularly after adjusting for age, physical activity, and sitting time (P = 0.028). Therefore, the higher load of RT is a critical factor in the body recomposition of postmenopausal women. Furthermore, the positive effects of body recomposition induced by RT extend to physical performance and muscle strength. [ABSTRACT FROM AUTHOR]

Purpose: The decline in physical performance, assessed by physical tests such as the timed up and go (TUG) test, is a consequence of reduced physiological reserves at higher levels of a hierarchical process. This occurs due to changes in muscle architecture, including atrophy and fat infiltration into the muscles, which in turn lead to changes in muscle function, resulting in reduced muscle strength and power and, consequently, affecting physical performance. This study investigated predictive factors for physical performance in breast cancer survivor (BCS), focusing on intramuscular adipose tissue (IMAT), quadríceps muscle area (QMA), and muscular power. Methods: This observational, analytical, and cross-sectional study included 23 women without a history of cancer (age, 58.5 ± 8.3 years; BMI, 27.2 ± 5.1 kg/m2) and 56 BCS (age, 58.5 ± 8.3 years; BMI, 27.2 ± 5.1 kg/m2). QMA and IMAT were assessed using computed tomography images. Muscular power and physical performance were measured using the 5-repetition sit-to-stand and TUG tests, respectively. Results: IMAT (r = 0.4, P < 0.01) and muscular power (r = − 0.4, P < 0.01) were associated with TUG performance in BCS, whereas QMA (r = − 0.22, P = 0.10) showed no significant association. QMA (r = 0.55, P < 0.01) was associated with muscular power, while no significant association was found between IMAT and muscular power (r = − 0.05, P = 0.73). Age explained 19% (P < 0.01) of TUG performance variability. Adding muscular power increased explanatory power by 12% (P < 0.01), and including IMAT further increased it by 7% (P = 0.02) for TUG performance. Collectively, age, muscular power, and IMAT accounted for 38% of the performance variance in the TUG test (age, B = 0.06, P = 0.043; muscular power, B = − 0.01, P = 0.002; IMAT, B = − 0.05, P = 0.020). Conclusions: Our findings suggest that IMAT and muscular power predict the physical performance of BCS, while QMA does not have the same predictive capability. [ABSTRACT FROM AUTHOR]

Purpose: To gain more knowledge about the mechanism (i.e., mediators) of resistance exercise (RE)-induced improvements in physical performance (PP), we seek to investigate whether improvements in muscle strength (MS), muscle power (MP), and lean body mass (LBM) and (or) self-reported fatigue (SRF) are mediators of the effect of RE on PP in breast cancer survivor women (BCSW). Methods: The volunteers were randomly divided into two groups: control group (CT; n = 9) and resistance exercise (RE; n = 11). The RE protocol consisted of three sets in each exercise (leg extension, leg curl, 45° leg press, and calf raise), between 8 and 12 repetitions per set, with an estimated load of 80% of one-repetition maximum (1RM), and three times a week on non-consecutive days for 12 weeks. The CT group performed only stretching exercises twice a week. SRF, maximal muscle power (Pmax), MP, LBM, and PP were assessed using the Brief Fatigue Inventory Questionnaire; 1RM test; isoinertial dynamometer; DXA; and walking speed, sit-to-stand (STS), and timed up and go (TUG) test, respectively. Results: Following 12 weeks, the RE group reduced SRF and increased MP, Pmax, LBM, and performance in all tests (walking speed, STS, and TUG) when compared with the CT group. There were significant associations of the changes in LBM, MS, Pmax, and SRF with changes in physical performance tests only in the RE group. Conclusion: Our findings suggest that improvements in LBM, MS, MP, and self-reported fatigue mediate the effect of resistance exercise on physical performance in BCSW. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to investigate whether the higher load resistance training with a cluster training sets (CS) design maximizes muscle power and strength gains when compared to higher load resistance training with a traditional sets (TS) design in postmenopausal women (PW). Methods: Each leg of 16 PW was randomly allocated into two groups: TS (n = 16 legs) and CS (n = 16 legs). Both groups performed three sets of four repetitions at 90% one repetition maximum (1RM), 3 s per muscle action, with a 1.5-min rest interval between sets, twice-weekly, for 8 weeks. Only CS group performed 30 s interrepetition rest periods. Results: Both groups similarly increased (P < 0.05) thigh muscle mass, muscle strength (1RM), and maximal muscle power. However, whereas the CS increased (P < 0.05) peak power at 40% and theoretical maximal velocity (V0), the TS increase theoretical maximal force (F0). The TS reduced slope of the force–velocity relationship when compared to the CS. Conclusions: Although both CS and TS design are similarly effective at improving muscle mass and strength and Pmax, TS and CS induce different changes in the force–velocity profile (Sfv) in PW. Thus, our findings suggest that TS may be a preferential RT design if the focus of training is a force–velocity profile more "force-oriented", whereas CS may be a preferential RT design if the focus of training is a force–velocity profile more "velocity-oriented". [ABSTRACT FROM AUTHOR]

This study evaluated the effect of resistance training (RT) volume on muscular strength and on indicators of abdominal adiposity, metabolic risk, and inflammation in post-menopausal women (PW). Thirty-two volunteers were randomly allocated into the following three groups: control (CT, no exercise, n = 11), low-volume RT (LV, three sets/exercise, n = 10), and high-volume RT (HV, six sets/exercise, n = 11). The LV and HV groups performed eight exercises at 70 % of one maximal repetition, three times a week, for 16 weeks. Muscular strength and indicators of abdominal adiposity, metabolic risk, and inflammation were measured at baseline and after 16 weeks. No differences were found in baseline measures between the groups. The PW showed excess weight and fat percentage (F%), large waist circumference (WC), high waist-hip ratio (WHR), and hypercholesterolemia and borderline values of glycated hemoglobin (HbA1c%). Following the RT, a similar increase in muscle strength and reduction in F% from baseline were found in both trained groups. In HV, a decrease in total cholesterol, LDL-c, WC, and WHR was noted. Moreover, the HV showed a lower change (delta%) of interleukin-6 (IL-6) when compared to CT (HV = 11.2 %, P25–75 = −7.6–28.4 % vs. CT = 99.55 %, P25–75 = 18.5–377.0 %, p = 0.049). In LV, a decrease was noted for HbA1c%. There were positive correlations (delta%) between WHR and IL-6 and between IL-6 and TC. These results suggest that while a low-volume RT improves HbA1c%, F%, and muscular strength, a high-volume RT is necessary to improve indicators of abdominal adiposity and lipid metabolism and also prevent IL-6 increases in PW. [ABSTRACT FROM AUTHOR]