Intramuscular adipose tissue, muscle area, and power as predictors of performance in breast cancer survivors.

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.

Effect of resistance training volume on body adiposity, metabolic risk, and inflammation in postmenopausal and older females: Systematic review and meta-analysis of randomized controlled trials.

PURPOSE: This meta-analytical study aimed to explore the effects of resistance training (RT) volume on body adiposity, metabolic risk, and inflammation in postmenopausal and older females. METHODS: A systematic search was performed for randomized controlled trials in PubMed, Scopus, Web of Science, and SciELO. Randomized controlled trials with postmenopausal and older females that compared RT effects on body adiposity, metabolic risk, and inflammation with a control group (CG) were included. Independent reviewers selected the studies, extracted the data, and performed the risk of bias and certainty of the evidence (Grading of Recommendations, Assessment, Development, and Evaluation (GRADE)) evaluations. Total body and abdominal adiposity, blood lipids, glucose, and C-reactive protein were included for meta-analysis. A random-effects model, standardized mean difference (Hedges' g), and 95% confidence interval (95%CI) were used for meta-analysis. RESULTS: Twenty randomized controlled trials (overall risk of bias: some concerns; GRADE: low to very low) with overweight/obese postmenopausal and older females were included. RT groups were divided into low-volume RT (LVRT, ∼44 sets/week) and high-volume RT (HVRT, ∼77 sets/week). Both RT groups presented improved body adiposity, metabolic risk, and inflammation when compared to CG. However, HVRT demonstrated higher effect sizes than LVRT for glucose (HVRT = -1.19; 95%CI: -1.63 to -0.74; LVRT = -0.78; 95%CI:-1.15 to -0.41) and C-reactive protein (HVRT = -1.00; 95%CI: -1.32 to -0.67; LVRT = -0.34; 95%CI, -0.63 to -0.04)) when compared to CG. CONCLUSION: Compared to CG, HVRT protocols elicit greater improvements in metabolic risk and inflammation outcomes than LVRT in overweight/obese postmenopausal and older females.

Predicting Functional Capacity From Measures of Muscle Mass in Postmenopausal Women.

BACKGROUND: Menopause increases body fat and decreases muscle mass and strength, which contribute to sarcopenia. The amount of appendicular muscle mass has been frequently used to diagnose sarcopenia. Different measures of appendicular muscle mass have been proposed. However, no studies have compared the most salient measure (appendicular muscle mass corrected by body fat) of the appendicular muscle mass to physical function in postmenopausal women. OBJECTIVE: To examine the association of 3 different measurements of appendicular muscle mass (absolute, corrected by stature, and corrected by body fat) with physical function in postmenopausal women. DESIGN: Cross-sectional descriptive study. SETTING: Outpatient geriatric and gynecological clinic. PARTICIPANTS: Forty-eight postmenopausal women with a mean age (standard deviation [SD]) of 62.1 ± 8.2 years, with mean (SD) length of menopause of 15.7 ± 9.8 years and mean (SD) body fat of 43.6% ± 9.8%. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Appendicular muscle mass measure was measured with dual-energy x-ray absorptiometry. Physical function was measured by a functional capacity questionnaire, a short physical performance battery, and a 6 minute-walk test. Muscle quality (leg extensor strength to lower-body mineral-free lean mass ratio) and sum of z scores (sum of each physical function tests z score) were performed to provide a global index of physical function. RESULTS: The regression analysis showed that appendicular muscle mass corrected by body fat was the strongest predictor of physical function. Each increase in the standard deviation of appendicular muscle mass corrected by body fat was associated with a mean sum of z score increase of 59% (standard deviation), whereas each increase in absolute appendicular muscle mass and appendicular muscle mass corrected by stature were associated with a mean sum of z scores decrease of 23% and 36%, respectively. Muscle quality was associated with appendicular muscle mass corrected by body fat. CONCLUSION: These findings indicate that appendicular muscle mass corrected by body fat is a better predictor of physical function than the other measures of appendicular muscle mass in postmenopausal women. LEVEL OF EVIDENCE: I.

Acute resistance exercise reduces increased gene expression in muscle atrophy of ovariectomised arthritic rats.

OBJECTIVE: We studied the effect of resistance exercise (RE) on mRNA levels of atrogin-1, MuRF-1, and myostatin in the gastrocnemius muscle of arthritic rats after loss of ovarian function (LOF). MATERIAL AND METHODS: Thirty female Wistar rats (nine weeks old, 195.3 ±17.4 grams) were randomly allocated into five groups: control group (CT-Sham; n = 6); group with rheumatoid arthritis (RA; n = 6); group with rheumatoid arthritis subjected to RE (RAEX; n = 6); ovariectomy group with rheumatoid arthritis (RAOV; n = 6); and an ovariectomy group with rheumatoid arthritis subjected to RE (RAOVEX; n = 6). After 15 days of intra-articular injections with Met-BSA the animals were subjected to RE and six hours after workout were euthanised. RESULTS: The rheumatoid arthritis provoked reduction in the cross-sectional area (CSA) of muscle fibres, but the CSA was lower in the RAOV when compared to the RA groups. Skeletal muscle atrogin-1 mRNA level was increased in arthritic rats (RA and RAOV), but the atrogin-1 level was higher in RAOV group when compared to other arthritic groups. The Muscle MuRF-1 mRNA level was also increased in the RAOV group. The increased atrogin-1 and MuRF-1 mRNA levels were lower in the RAOVEX group than in the RAOV group. The myostatin mRNA level was similar in all groups, except for the RAOVEX group, in which it was lower than the other groups. CONCLUSIONS: LOF results in increased loss of skeletal muscle-related ubiquitin ligases (atrogin-1 and MuRF-1). However, the RE reduces the atrogin-1, MuRF-1, and myostatin mRNA levels in muscle of arthritic rats affected by LOF.

Low-load resistance training promotes muscular adaptation regardless of vascular occlusion, load, or volume.

PURPOSE: This study investigates the impact of two different intensities and different volumes of low-load resistance training (LLRT) with and without blood flow restriction on the adaptation of muscle strength and size. METHODS: The sample was divided into five groups: one set of 20 % of one repetition maximum (1RM), three sets of 20 % of 1RM, one set of 50 % of 1RM, three sets of 50 % of 1RM, or control. LLRT was performed with (OC) or without (NOC) vascular occlusion, which was selected randomly for each subject. The maximal muscle strength (leg extension; 1RM) and the cross-sectional area (quadriceps; CSA) were assessed at baseline and after 8 weeks of LLRT. RESULTS: 1RM performance was increased in both groups after 8 weeks of training: OC (1 × 50 % = 20.6 %; 3 × 50 % = 20.9 %; 1 × 20 % = 26.6 %; 3 × 20 % = 21.6 %) and NOC (1 × 50 % = 18.6 %; 3 × 50 % = 26.8 %; 1 × 20 % = 18.5 %; 3 × 20 % = 21.6 %; 3 × 20 % = 24.7 %) compared with the control group (-1.7 %). Additionally, the CSA was increased in both groups: OC (1 × 50 % = 2.4 %; 3 × 50 % = 3.8 %; 1 × 20 % = 4.6 %; 3 × 20 % = 4.8 %) and NOC (1 × 50 % = 2.4 %; 3 × 50 % = 1.5 %; 1 × 20 % = 4.3 %; 3 × 20 % = 3.8 %) compared with the control group (-0.7 %). There were no significant differences between the OC and NOC groups. CONCLUSION: We conclude that 8 weeks of LLRT until failure in novice young lifters, regardless of occlusion, load or volume, produces similar magnitudes of muscular hypertrophy and strength.