Dataset Information

Type 2 diabetes does not account for ethnic differences in exercise capacity or skeletal muscle function in older adults.

ABSTRACT:

Aims/hypothesis

The aim of this study was to compare exercise capacity, strength and skeletal muscle perfusion during exercise, and oxidative capacity between South Asians, African Caribbeans and Europeans, and determine what effect ethnic differences in the prevalence of type 2 diabetes has on these functional outcomes.

Methods

In total, 708 participants (aged [mean±SD] 73?±?7 years, 56% male) were recruited from the Southall and Brent Revisited (SABRE) study, a UK population-based cohort comprised of Europeans (n?=?311) and South Asian (n?=?232) and African Caribbean (n?=?165) migrants. Measurements of exercise capacity using a 6 min stepper test (6MST), including measurement of oxygen consumption ([Formula: see text]) and grip strength, were performed. Skeletal muscle was assessed using near infrared spectroscopy (NIRS); measures included changes in tissue saturation index (?TSI%) with exercise and oxidative capacity (muscle oxygen consumption recovery, represented by a time constant [?]). Analysis was by multiple linear regression.

Results

When adjusted for age and sex, in South Asians and African Caribbeans, exercise capacity was reduced compared with Europeans ([Formula: see text] [ml min^-1 kg^-1]: ??=?-1.2 [95% CI -1.9, -0.4], p?=?0.002, and ? -1.7 [95% CI -2.5, -0.8], p?1c (and fat-free mass for grip strength). However, the differences between Europeans and South Asians were no longer statistically significant after adjustment for other possible mediators or confounders (including physical activity, waist-to-hip ratio, cardiovascular disease or hypertension, smoking, haemoglobin levels or ?-blocker use). The difference in ?TSI% between Europeans and South Asians was marginally attenuated after adjustment for type 2 diabetes or HbA_1c and was also no longer statistically significant after adjusting for other confounders; however, ? remained significantly longer in South Asians vs Europeans despite adjustment for all confounders.

Conclusions/interpretation

Reduced exercise capacity in South Asians and African Caribbeans is unexplained by higher rates of type 2 diabetes. Poorer exercise tolerance in these populations, and impaired muscle function and perfusion in South Asians, may contribute to the higher morbidity burden of UK ethnic minority groups in older age.

SUBMITTER: Jones S

PROVIDER: S-EPMC6997264 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Publications

Type 2 diabetes does not account for ethnic differences in exercise capacity or skeletal muscle function in older adults.

Jones Siana S Tillin Therese T Williams Suzanne S Eastwood Sophie V SV Hughes Alun D AD Chaturvedi Nishi N

Diabetologia 20191209 3

<h4>Aims/hypothesis</h4>The aim of this study was to compare exercise capacity, strength and skeletal muscle perfusion during exercise, and oxidative capacity between South Asians, African Caribbeans and Europeans, and determine what effect ethnic differences in the prevalence of type 2 diabetes has on these functional outcomes.<h4>Methods</h4>In total, 708 participants (aged [mean±SD] 73 ± 7 years, 56% male) were recruited from the Southall and Brent Revisited (SABRE) study, a UK population-bas ...[more]

PMID: 31820039

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Project description: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.

Project description:Key pointsHealthy older adults exhibit lower cardiorespiratory fitness ( V̇O2peak ) than young in the absence of any age-related difference in skeletal muscle mitochondrial capacity, suggesting central haemodynamics plays a larger role in age-related declines in V̇O2peak . Total physical activity did not differ by age, but moderate-to-vigorous physical activity was lower in older compared to young adults. Moderate-to-vigorous physical activity is associated with V̇O2peak and muscle oxidative capacity, but physical inactivity cannot entirely explain the age-related reduction in V̇O2peak .AbstractDeclining fitness ( V̇O2peak ) is a hallmark of ageing and believed to arise from decreased oxygen delivery and reduced muscle oxidative capacity. Physical activity is a modifiable lifestyle factor that is critical when evaluating the effects of age on parameters of fitness and energy metabolism. The objective was to evaluate the effects of age and sex on V̇O2peak , muscle mitochondrial physiology, and physical activity in young and older adults. An additional objective was to assess the contribution of skeletal muscle oxidative capacity to age-related reductions in V̇O2peak and determine if age-related variation in V̇O2peak and muscle oxidative capacity could be explained on the basis of physical activity levels. In 23 young and 52 older men and women measurements were made of V̇O2peak , mitochondrial physiology in permeabilized muscle fibres, and free-living physical activity by accelerometry. Regression analyses were used to evaluate associations between age and V̇O2peak , mitochondrial function, and physical activity. Significant age-related reductions were observed for V̇O2peak (P < 0.001), but not muscle mitochondrial capacity. Total daily step counts did not decrease with age, but older adults showed lower moderate-to-vigorous physical activity, which was associated with V̇O2peak (R2 = 0.323, P < 0.001) and muscle oxidative capacity (R2 = 0.086, P = 0.011). After adjusting for sex and physical activity, age was negatively associated with V̇O2peak but not muscle oxidative capacity. Healthy older adults exhibit lower V̇O2peak but preserved mitochondrial capacity compared to young. Physical activity, particularly moderate-to-vigorous, is a key factor in observed age-related changes in fitness and muscle oxidative capacity, but cannot entirely explain the age-related reduction in V̇O2peak .

Dataset Information

Type 2 diabetes does not account for ethnic differences in exercise capacity or skeletal muscle function in older adults.

Aims/hypothesis

Methods

Results

Conclusions/interpretation

Publications

Type 2 diabetes does not account for ethnic differences in exercise capacity or skeletal muscle function in older adults.

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