1.
Low skeletal muscle capillarization limits muscle adaptation to resistance exercise training in older adults.
Moro, T, Brightwell, CR, Phalen, DE, McKenna, CF, Lane, SJ, Porter, C, Volpi, E, Rasmussen, BB, Fry, CS
Experimental gerontology. 2019;:110723
-
-
Free full text
-
Abstract
OBJECTIVES Adequate muscle perfusion supports the transport of nutrients, oxygen and hormones into muscle fibers. Aging is associated with a substantial decrease in skeletal muscle capillarization, fiber size and oxidative capacity, which may be improved with regular physical activity. The aim of this study was to investigate the relationship between muscle capillarization and indices of muscle hypertrophy (i.e. lean mass; fiber cross sectional area (CSA)) in older adults before and after 12 weeks of progressive resistance exercise training (RET). DESIGN Interventional study SETTING AND PARTICIPANTS 19 subjects (10 male and 9 female; 71.1 ± 4.3 years; 27.6 ± 3.2 BMI) were enrolled in the study and performed a whole body RET program for 12 weeks. Subjects where then retrospectively divided into a LOW or HIGH group, based on their pre-RET capillary-to-fiber perimeter exchange index (CFPE). Physical activity level, indices of capillarization (capillaries-to-fiber ratio, C:Fi; CFPE index and capillary-to-fiber interface, LC-PF index), muscle hypertrophy, muscle protein turnover and mitochondrial function were assessed before and after RET. RESULTS Basal capillarization (C:Fi; CFPE and LP-CF index) correlates with daily physical activity level (C:Fi, r = 0.57, p = 0.019; CFPE index, r = 0.55, p = 0.024; LC-PF index, r = 0.56, p = 0.022) and CFPE and LC-PF indices were also positively associated with oxidative capacity (respectively r = 0.45, p = 0.06; r = 0.67, p = 0.004). Following RET, subjects in the HIGH group underwent hypertrophy with significant improvements in muscle protein synthesis and muscle fiber CSA (p < 0.05). However, RET did not promote muscle hypertrophy in the LOW group, but RET significantly increased muscle capillary density (p < 0.05). CONCLUSION/IMPLICATIONS Muscle fiber capillarization before starting an exercise training program may be predictive of the muscle hypertrophic response to RET in older adults. Increases in muscle fiber size following RET appear to be blunted when muscle capillarization is low, suggesting that an adequate initial capillarization is critical to achieve a meaningful degree of muscle adaptation to RET.
2.
ACTN3 Gene and Susceptibility to Sarcopenia and Osteoporotic Status in Older Korean Adults.
Cho, J, Lee, I, Kang, H
BioMed research international. 2017;:4239648
Abstract
BACKGROUND Little information is available about molecular markers for sarcopenia and osteoporosis in Asian populations. OBJECTIVE This study investigated the association of the ACTN3 polymorphism with sarcopenia and osteoporotic status in older Korean adults. METHODS Older Korean 62 men and 270 women (mean age 73.7 ± 6.6 years) participated in this study. Body mass index, percent body fatness, appendicular skeletal muscle mass, and bone mineral density of the lumbar spine, femur, and total body were analyzed with dual-energy X-ray absorptiometry. ACTN3 R/X genotyping was determined using TaqMan probes. RESULTS Determination of odds ratios (ORs) and 95% confidence intervals (CIs) using binary logistic regression analyses showed that XX homozygotes were at a significantly higher risk of sarcopenia (OR = 2.056, 95% CI = 1.024-4.127, p = 0.043) and osteoporosis (OR = 2.794, 95% CI = 1.208-5.461, p = 0.016) than RR homozygotes (reference group, OR = 1). The OR of XX homozygotes for having sarcopenia remained significant (OR = 2.237, 95% CI = 1.044-4.836, p = 0.038) after adjustments for age, gender, body fatness, and serum vitamin D. The OR of XX homozygotes for having osteoporosis was no longer significant (OR = 2.682, 95% CI = 0.960-7.942, p = 0.075) after adjustments for the covariates. CONCLUSION Our findings suggest that the ACTN3 R577X genotype may influence decline in muscle and bone health phenotypes in older Korean adults.
3.
Whole-body electromyostimulation as a means to impact muscle mass and abdominal body fat in lean, sedentary, older female adults: subanalysis of the TEST-III trial.
Kemmler, W, von Stengel, S
Clinical interventions in aging. 2013;:1353-64
Abstract
BACKGROUND The primary aim of this study was to determine the effect of 12 months of whole-body electromyostimulation (WB-EMS) exercise on appendicular muscle mass and abdominal fat mass in subjects specifically at risk for sarcopenia and abdominal obesity, but unable or unwilling to exercise conventionally. METHODS Forty-six lean, nonsportive (<60 minutes of exercise per week), elderly women (aged 75 ± 4 years) with abdominal obesity according to International Diabetes Federation criteria were randomly assigned to either a WB-EMS group (n=23) which performed 18 minutes of intermittent, bipolar WB-EMS (85 Hz) three sessions in 14 days or an "active" control group (n=23). Whole-body and regional body composition was assessed by dual energy X-ray absorptiometry to determine appendicular muscle mass, upper leg muscle mass, abdominal fat mass, and upper leg fat mass. Maximum strength of the leg extensors was determined isometrically by force plates. RESULTS After 12 months, significant intergroup differences were detected for the primary end-points of appendicular muscle mass (0.5% ± 2.0% for the WB-EMS group versus -0.8% ± 2.0% for the control group, P=0.025) and abdominal fat mass (-1.2% ± 5.9% for the WB-EMS group versus 2.4% ± 5.8% for the control group, P=0.038). Further, upper leg lean muscle mass changed favorably in the WB-EMS group (0.5% ± 2.5% versus -0.9% ± 1.9%, in the control group, P=0.033), while effects for upper leg fat mass were borderline nonsignificant (-0.8% ± 3.5% for the WB-EMS group versus 1.0% ± 2.6% for the control group, P=0.050). With respect to functional parameters, the effects for leg extensor strength were again significant, with more favorable changes in the WB-EMS group (9.1% ± 11.2% versus 1.0% ± 8.1% in the control group, P=0.010). CONCLUSION In summary, WB-EMS showed positive effects on the parameters of sarcopenia and regional fat accumulation. Further, considering the good acceptance of this technology by this nonsportive elderly cohort at risk for sarcopenia and abdominal obesity, WB-EMS may be a less off-putting alternative to impact appendicular muscle mass and abdominal fat mass, at least for subjects unwilling or unable to exercise conventionally.