Adiposity attenuates muscle quality and the adaptive response to resistance exercise in non-obese, healthy adults

Stem cell secretome treatment improves whole-body metabolism, reduces adiposity, and promotes skeletal muscle function in aged mice

Aging coincides with the progressive loss of muscle mass and strength, increased adiposity, and diminished physical function. Accordingly, interventions aimed at improving muscle, metabolic, and/or physical health are of interest to mitigate the adverse effects of aging. In this study, we tested a stem cell secretome product, which contains extracellular vesicles and growth, cytoskeletal remodeling, and immunomodulatory factors. We examined the effects of 4 weeks of 2×/week unilateral intramuscular secretome injections (quadriceps) in ambulatory aged male C57BL/6 mice (22-24 months) compared to saline-injected aged-matched controls. Secretome delivery substantially increased whole-body lean mass and decreased fat mass, corresponding to higher myofiber cross-sectional area and smaller adipocyte size, respectively. Secretome-treated mice also had greater whole-body physical function (grip strength and rotarod performance) and had higher energy expenditure and physical activity levels compared to control mice. Furthermore, secretome-treated mice had greater skeletal muscle Pax7+ cell abundance, capillary density, collagen IV turnover, reduced intramuscular lipids, and greater Akt and hormone sensitive lipase phosphorylation in adipose tissue. Finally, secretome treatment in vitro directly enhanced muscle cell growth and IL-6 production, and in adipocytes, it reduced lipid content and improved insulin sensitivity. Moreover, indirect treatment with secretome-treated myotube culture media also enhanced muscle cell growth and adipocyte size reduction. Together, these data suggest that intramuscular treatment with a stem cell secretome improves whole-body metabolism, physical function, and remodels skeletal muscle and adipose tissue in aged mice.

Obesity blunts insulin sensitivity improvements and attenuates strength gains following resistance training in nondiabetic men

PURPOSE

Impaired insulin sensitivity is central in the etiology of type 2 diabetes in people with obesity. The effectiveness of resistance training (RE) alone in improving insulin sensitivity in people with obesity is undetermined. This study aimed to determine the influence of obesity on insulin sensitivity responses to RE.

METHODS

Nineteen sedentary men were allocated to Lean (BMI 22.7 ± 2.5 kg m-2; n = 10) or Obese group (BMI 33.2 ± 3.2 kg m-2; n = 9). Participants were evaluated before and after a 10-week supervised progressive RE (3 sets of 10 repetition maximum (RM), 3 d/wk) for insulin sensitivity indexes using an oral glucose tolerance test, body composition using anthropometrics, and strength using 1RM.

RESULTS

Groups were matched at baseline for all variables except for body composition and absolute strength. Body fat was not changed in both groups. Matsuda insulin sensitivity index, hepatic insulin resistance, and insulin area under the curve improved by 64.3 ± 61.9 unit, - 58.2 ± 102.9 unit, 2.3 ± 4.1 unit, and - 721.6 ± 858.2 µU/ml, respectively, only in the Lean group. The increased 1RM% for leg press was greater in the Lean (49.5 ± 18.7%) than in the Obese (31.5 ± 13.9), but not different for bench press (18.0 ± 9.1% vs. 16.4 ± 6.0%, respectively).

CONCLUSION

Sustained obesity precludes insulin sensitivity improvements and attenuates strength gains in response to progressive RE. Additional strategies such as caloric restriction might be necessary for RE to improve insulin sensitivity, particularly at high levels of obesity.

Comparison of time-matched aerobic, resistance or combined exercise training in women living with obesity: The EXOFFIT study

Background

Improvements in cardiorespiratory fitness (CRF) have been shown to largely attenuate the negative health risks associated with obesity. To date, literature on women with obesity has focused upon the evaluation of aerobic-based exercise interventions. Hence, there is a need to evaluate resistance and combined interventions with this cohort.

Objective

This study aimed to evaluate the feasibility and efficacy of three exercise modalities in women with obesity for improving CRF, strength, body composition and other health outcomes.

Methods

Sixty-seven women with obesity were randomly assigned to the control (CON) or one of three exercise groups (aerobic [AE], resistance [RE], COM). Exercise groups were trained x3 times/week for 12 weeks (up to 150-min/week). Feasibility outcomes included adherence, attendance, recruitment and retention rates and adverse events. Secondary outcomes were CRF (predicted VO2 max), body composition (body weight [BW], waist circumference [WC], body fat percentage [%BF], fat mass [FM] and lean mass) and strength (5RM bench press, leg dynamometry, grip strength) and self-reported measures of physical activity, mood, sleep, pain and quality of life.

Results

Findings support the feasibility of all three exercise modalities in terms of adherence, attendance, and retention. Interventions with a resistance component (COM and RE) were associated with the greatest improvements across the broad range of health outcomes measured. Combined was the most promising for body composition outcomes including body mass index (Effect size [ES] = 0.79, p = 0.04), BW (ES = 0.75, p = 0.05), %BF (ES = 0.77, p = 0.04), FM (ES = 0.83, p = 0.03) and WC (ES = 0.90, p = 0.02), physical activity (i.e., moderate physical activity [ES = 0.69, p = 0.07), mood (ES = 0.83, p = 0.03) and sleep (ES = 0.78, p = 0.04). Resistance was most promising for CRF (ES = 1.47, p = 0.002), strength (i.e., bench press [ES = 2.88, p=<0.001]) and pain (i.e., pain severity [ES = 0.40, p = 0.31]).

Conclusions

For health outcomes, these results indicate the importance of including a resistance component when prescribing exercise for women with obesity to achieve meaningful improvements.

CLINICAL TRIAL REGISTRATION

ISRCTN13517067.

Activin type I receptor polymorphisms and body composition in older individuals with sarcopenia-Analyses from the LACE randomised controlled trial

BACKGROUND

Ageing is associated with changes in body composition including an overall reduction in muscle mass and a proportionate increase in fat mass. Sarcopenia is characterised by losses in both muscle mass and strength. Body composition and muscle strength are at least in part genetically determined, consequently polymorphisms in pathways important in muscle biology (e.g., the activin/myostatin signalling pathway) are hypothesised to contribute to the development of sarcopenia.

METHODS

We compared regional body composition measured by DXA with genotypes for two polymorphisms (rs10783486, minor allele frequency (MAF) = 0.26 and rs2854464, MAF = 0.26) in the activin 1B receptor (ACVR1B) determined by PCR in a cross-sectional analysis of DNA from 110 older individuals with sarcopenia from the LACE trial.

RESULTS

Neither muscle mass nor strength showed any significant associations with either genotype in this cohort. Initial analysis of rs10783486 showed that males with the AA/AG genotype were taller than GG males (174±7cm vs 170±5cm, p = 0.023) and had higher arm fat mass, (median higher by 15%, p = 0.008), and leg fat mass (median higher by 14%, p = 0.042). After correcting for height, arm fat mass remained significantly higher (median higher by 4% padj = 0.024). No associations (adjusted or unadjusted) were seen in females. Similar analysis of the rs2854464 allele showed a similar pattern with the presence of the minor allele (GG/AG) being associated with greater height (GG/AG = 174±7 cm vs AA = 170 ±5cm, p = 0.017) and greater arm fat mass (median higher by 16%, p = 0.023). Again, the difference in arm fat remained after correction for height. No similar associations were seen in females analysed alone.

CONCLUSION

These data suggest that polymorphic variation in the ACVR1B locus could be associated with body composition in older males. The activin/myostatin pathway might offer a novel potential target to prevent fat accumulation in older individuals.

Muscle Quality Index is inversely associated with psychosocial variables among Chilean adolescents

A good muscle quality index (MQI) may have an inverse relationship with psychosocial variables of depression, anxiety, and stress in adolescents. Unfortunately, little scientific evidence has related MQI to psychosocial variables in this population. Therefore, this research aimed to determine the relationship between the MQI and psychosocial variables of depression, anxiety, and stress in Chilean adolescents. In this quantitative correlational design study, sixty adolescents participated voluntarily (mean ± standard deviation [SD]: age 15.11 ± 1.78 years). Anthropometric parameters, prehensile strength, MQI, and psychosocial variables were evaluated. The results showed that adolescents with high levels of MQI presented lower levels of depression (7.50 ± 6.06 vs. 10.97 ± 5.94), anxiety (5.64 ± 4.81 vs. 9.66 ± 5.12), and stress (6.79 ± 5.09 vs. 10 ± 5.58), in addition to reported lower abdominal obesity (WtHR, 0.47 ± 0.07 vs. 0.52 ± 0.07) than those with low levels of MQI. The group with high levels of MQI reported a higher prevalence of nonanxiety (81.3%, p = 0.031) and a lower prevalence of abdominal obesity (55.8%, p = 0.023). Likewise, a significant inverse association was evidenced between MQI and depression (β; -6.18, 95% CI; -10.11: -2.25, p = 0.003), anxiety (β; -6.61, 95% CI; -9.83: -3.39, p < 0.001) and stress (β; -4.90, 95% CI; -8.49: -1.32 p = 0.008). In conclusion, the results suggest that high levels of MQI are associated with a higher prevalence of nonanxiety in adolescents and a significant inverse association between MQI and levels of depression, anxiety, and stress.

Effects of resistance training on body recomposition, muscular strength, and phase angle in older women with different fat mass levels

AIMS

The concomitant increase in skeletal muscle mass (SMM) and decrease in fat mass has been termed body recomposition. This study aimed to analyze the influence of pre-training levels of fat mass on body recomposition, muscular strength, and (phase angle) PhA after 24 weeks of resistance training (RT) in older women.

METHODS

Data from 99 older women (68.6 ± 5.7 years, 65.7 ± 8.6 kg, 155.1 ± 5.8 cm, 27.2 ± 3.1 kg/m²) was retrospectively analyzed. Participants were separated into tertiles according to the amount of fat mass at baseline as follows: low fat mass (L-FM, n = 33), moderate fat mass (M-FM, n = 33), and high fat mass (H-FM, n = 33). The participants underwent a RT program consisting of eight exercises, three sets per exercise, with a load between 8 and 15 RM, performed three times per week for 24 weeks. The SMM and fat mass were evaluated by dual-energy X-ray absorptiometry (DXA). Body recomposition was determined by the composite Z-score of changes in SMM and fat mass. One repetition maximum (1RM) tests in chest press, knee extension, and preacher curl were assessed to verify muscular strength. Bioimpedance was used to determine phase angle.

RESULTS

Results indicated that after the RT period, a greater positive body recomposition was observed in the L-FM group than in M-FM and H-FM groups. Moreover, all groups increased muscular strength and phase angle with no significant difference among groups (P > 0.05).

CONCLUSION

The present study results suggest that the initial amount of fat mass influences the body recomposition induced by RT in older women, with those with lower pre-training fat mass levels presenting higher levels of body recomposition. However, improvements in muscular strength and phase angle are not dependent on the amount of initial fat mass in older women.

Heterogeneity in resistance training-induced muscle strength responses is associated with training frequency and insulin resistance in postmenopausal women

BACKGROUND

In older adults, muscle strength (MS), a key component of sarcopenia, is essential to maintaining independence and physical capacity. The rate of muscle strength decline typically accelerates during the menopausal transition. Although MS has been shown to increase with resistance training (RT), the response to training is quite heterogeneous. Thus, if contributing factors to RT non-responsiveness to MS gains are identified, it may be possible to develop more effective and personalized ways to improve MS or identify individuals who may benefit from RT interventions. This study assessed potential factors that may contribute to MS response heterogeneity in postmenopausal women: training frequency, serum FSH and estrogen levels, adiposity, inflammation marker, and insulin resistance.

METHODS

One hundred and thirteen individuals participated in a 16-week program of supervised RT (3 sets, 8-12 repetitions, and 2-3 times/week). A control group (CTL, n = 63 - no performed the RT) was used as the comparator arm. Body composition (skinfold) and blood samples (metabolic and inflammatory indicators and hormones) were measured at baseline. Knee extensor strength (1RM) was measured at baseline, 8 weeks, and 16 weeks.

RESULTS

Only the RT group increased 1RM after 8 weeks (RT = 14 ± 12% vs. CTL = 6 ± 15%). Both groups increased 1RM after 16 weeks, with the RT group showing a greater increase than the CTL group (RT = 31 ± 23% vs CTL = 13 ± 25%). After 8 weeks of RT, 41 (36% of total) individuals were considered non-responders (based on control group responses) and 27 (24% of total) individuals after 16 weeks. At week 8, lower RT frequency (2 times/week vs. 3 times/week) was associated with higher odds of being non-responder (3 times, P = 0.048). At week 16, lower RT frequency (13 times, P = 0.009) and higher HOMA-IR (for every unit increase, odds increase by 40%, P = 0.022) were associated with higher odds of being non-responder. Higher QUICKI was associated with lower odds of being non-responder (for every unit increase, odds decrease by 16%, P = 0.039). Moreover, higher RT frequency (17 times, P = 0.028) and higher QUICKI (for every unit increase, odds increase by 41%, P = 0.017) were associated with higher odds of becoming a responder at week 16, being a non-responder at week 8.

CONCLUSION

Heterogeneity in RT-induced MS responses is associated with training frequency and insulin resistance in postmenopausal women.

Effects of Training with Different Modes of Strength Intervention on Psychosocial Disorders in Adolescents: A Systematic Review and Meta-Analysis

Physical exercise has a positive impact on anxiety and depression. However, the evidence that associates strength training with a decrease in adolescents' psychosocial disorders is scarce. Consequently, the objective was to analyze the effects of training with different modes of strength intervention on anxiety, stress, and depression in adolescents. The search was designed according to PRISMA^®. We searched WoS, Scopus, SPORTDiscus, PubMed, and MEDLINE (2010-2020). Methodological quality and risk of bias were assessed with the Cochrane Collaboration. The analysis was carried out with a standardized mean difference (SMD) pooled using the Hedges g test (95% CI). The Main Outcome Measures were: anxiety, stress, and depression in adolescents post strength training. Nine studies were included in the systematic review and seven in the meta-analysis. These studies showed a large and significant effect of strength training on anxiety (SMD = -1.75; CI = 95%: -3.03, -0.48; p = 0.007) and depression (SMD = -1.61; CI = 95%: -2.54, -0.67, p = 0.0007). In conclusion, training with different modes of strength intervention have shown control over anxiety and depression in adolescents. However, conventional strength training seems to have better results than other modes of strength intervention.

Whole-body electrical stimulation as a strategy to improve functional capacity and preserver lean mass after bariatric surgery: a randomized triple-blind controlled trial

BACKGROUND/OBJECTIVES

Bariatric surgery (BS) is a successful, long-lasting treatment option for obese. The early postoperative (PO) period is followed by dietary restriction and physical inactivity, leading to declines in muscle mass and functional capacity. Whole-body electromyostimulation (WB-EMS) may be a feasible and potential early rehabilitation strategy post BS. The aim was to evaluate the effects of WB-EMS with exercise training (Fe) on functional capacity, body composition, blood biomarkers, muscle strength, and endurance post BS.

SUBJECTS/METHODS

This is a randomized, triple-blind, sham-controlled trial. Thirty-five volunteers underwent a Roux-en-Y gastric bypass and were randomized into a WB-EMS (WB-EMSG) or control group (ShamG). Preoperative evaluations consisted of maximal and submaximal exercise testing, body composition, blood biomarkers, quadriceps strength, and endurance. After discharge, functional capacity and body composition were obtained. Exercise training protocols in both groups consisted of 14 dynamic exercises, 5 days per week, completing 30 sessions. The WB-EMSG also underwent an electrical stimulation protocol (Endurance: 85 Hz, 350 ms, 6 s of strain, 4 f of rest; Strength: 30 Hz, 350 ms, 4 s of strain, 10 seconds of rest, with bipolar electrical pulse). After intervention, subjects were reevaluated.

RESULTS

The protocol started on average 6.7 ± 3.7 days after discharge. Both groups presented with a decline in functional capacity after BS (p < 0.05) and a reduction in all body composition measurements (p < 0.05). The exercise training program led to significant improvements in functional capacity (ShamG - PO: 453.8 ± 66.1 m, Post: 519.2 ± 62.8 m; WB-EMSG- PO: 435.9 ± 74.5, Post: 562.5 ± 66.4 m, p < 0.05), however, only the WB-EMSG demonstrated significant changes of distance walked (interaction time vs group effect, p < 0.05). In addition, adiponectin significantly increased only in the WB-EMSG (p < 0.05). The WB-EMSG was also able to preserve muscle strength, endurance, and fatigue index, while the ShamG demonstrated significant decline (p < 0.05).

CONCLUSION

WB-EMS + Fe can be an attractive and feasible method following BS to enhance functional capacity and prevent deterioration of muscle function in the early PO.

CLINICAL TRIAL REGISTRATION

ReBEC, RBR-99qw5h, on 20 February 2015.

Association of metabolic phenotypes, grip strength and diabetes risk: The 15-year follow-up of The North West Adelaide Health Study, Australia

BACKGROUND

The association of diabetes risk in the long-term, metabolic phenotypes (MP) and muscle strength is unclear. We aimed to investigate the association between strictly defined MP, grip strength (GS) and diabetes.

MATERIAL AND METHODS

MP were defined according to BMI and presence of any individual metabolic abnormality for ≥18 years, in participants of the North West Adelaide Health Study (Australia) free of diabetes at baseline. The association of MP and dominant hand GS with incident diabetes over 15-years follow-up and the moderation effect of GS on the association between diabetes and MP were investigated by logistic regression models.

RESULTS

Of 3039 participants followed over 13.3 years (SD 2.6), 236 (7.8%) developed diabetes. Compared to the metabolically healthy (MH) normal weight phenotype, the metabolically unhealthy (MU) overweight (OR 6.15, 95%CI 2.43-15.59) and obese (OR 12.32, 95%CI 4.97-30.52) phenotypes were associated with a high risk of diabetes, but not the MU normal weight (OR 1.73, 95%CI 0.57-5.25), MH overweight (OR 1.15, 95%CI 0.31-4.31) or MH obese phenotypes (OR 0.77, 0.07-8.89). GS was inversely associated with diabetes (OR 0.97, 95% CI 0.95-0.99) and attenuated the risk associated with MU overweight (beta = -0.296, p = 0.039) and MU normal weight (beta = -0.773; p for interaction = 0.009).

CONCLUSION

Strictly defined MP (rather than based on metabolic syndrome criteria) and GS, a proxy of muscle strength, might be useful for stratifying the risk of diabetes in the long-term. Improving muscle strength might be an important strategy to reduce diabetes risk.

Resistance training leads to large improvements in strength and moderate improvements in physical function in adults who are overweight or obese: a systematic review

QUESTIONS

What are the effects of resistance training on muscle strength, physical function and muscle power in adults who are overweight or obese? Which factors moderate the effects?

DESIGN

Systematic review of randomised controlled trials, with random effects meta-analyses and meta-regressions.

PARTICIPANTS

Adults who are overweight or obese.

INTERVENTION

Resistance training lasting ≥ 4 weeks.

OUTCOME MEASURES

Muscle strength, muscle power and physical function.

RESULTS

Thirty trials with 1,416 participants met the eligibility criteria. Pooled analyses indicated that resistance training has a large beneficial effect on muscle strength (SMD 1.39, 95% CI 1.05 to 1.73, I² = 85%) and a moderate effect on physical function (SMD 0.67, 95% CI 0.25 to 1.08, I² = 71%) in adults who are overweight or obese. However, the effect of resistance training on muscle power was unclear (SMD 0.42, 95% CI -3.3 to 4.2, I² = 46%). The effect of resistance training on strength was greatest for the upper body (versus lower/whole body: β = 0.35, 95% CI 0.05 to 0.66) and in dynamic strength tests (versus isometric/isokinetic: β = 1.20, 95% CI 0.60 to 1.81), although trials judged to have good methodological quality reported statistically smaller effects (versus poor/fair quality: β = -1.21, 95% CI -2.35 to -0.07). Concomitant calorie restriction did not modify strength gains but reduced the effect of resistance training on physical function (β = -0.79, 95% CI -1.41 to -0.17). Small study effects were evident for strength outcomes (β = 5.9, p < 0.001).

CONCLUSIONS

Resistance training has a large positive effect on muscle strength and a moderate effect on physical function in adults who are overweight or obese. However, the effect of resistance training on muscle power is uncertain. In addition, concomitant calorie restriction may compromise the functional adaptations to resistance training.

REGISTRATION

PROSPERO CRD42019146394.

Dynapenic Abdominal Obesity as a Risk Factor for Worse Trajectories of ADL Disability Among Older Adults: The ELSA Cohort Study

Background

There is little epidemiological evidence demonstrating that dynapenic abdominal obese individuals have worse trajectories of disability than those with dynapenia and abdominal obesity alone. Our aim was to investigate whether dynapenic abdominal obesity can result in worse trajectories of activities of daily living (ADL) over 8 years of follow-up.

Methods

We used longitudinal data from 3,723 participants free from ADL disability at baseline from the English Longitudinal Study of Ageing. Using measures of handgrip strength (<26 kg for men; <16 kg for women) and waist circumference (>102 cm for men; >88 cm for women), participants were classified into four groups: nondynapenic/nonabdominal obese (reference group), abdominal obese only, dynapenic only, and dynapenic abdominal obese. We used generalized linear mixed models with ADL as the outcome and the four groups according to dynapenia and abdominal obesity status as the main exposure controlled by sociodemographic, behavioral, and clinical characteristics.

Results

The estimated change over time in ADL disability was significantly higher for participants with dynapenic abdominal obesity compared with those with neither condition (+0.018, 95% CI: 0.008 to 0.027). Compared with the results of our main analysis (which took into account the combination of dynapenia and abdominal obesity on the rate of change in ADL), the results of our sensitivity analysis—which examined dynapenia and abdominal obesity only as independent conditions—showed an overestimation of the associations of dynapenia only and of abdominal obesity only on the ADL disability trajectories.

Conclusions

Dynapenic abdominal obesity is an important risk factor for functional decline in older adults.

Reference values for the Unsupported Upper Limb Exercise test in healthy adults in Brazil

Objective:

To establish reference values for the Unsupported Upper Limb EXercise (UULEX) test, which measures peak arm exercise capacity, in healthy adults in Brazil.

Methods:

This was a cross-sectional study, involving presumably healthy individuals ≥ 30 years of age who completed questionnaires and underwent spirometry. All of the individuals underwent two UULEX tests 30-min apart. The outcome measure was the maximum time (in min) to completion of the test.

Results:

We included 100 individuals between 30 and 80 years of age. The mean test completion time was 11.99 ± 1.90 min among the women and 12.89 ± 2.15 min among the men (p = 0.03). The test completion time showed statistically significant correlations with age (r = −0.48; p < 0.001), gender (r = 0.28; p = 0.004), body mass index (BMI, r = −0.20; p = 0.05), and height (r = 0.28; p = 0.005). Linear regression analysis showed that the predictors of UULEX completion time were age (p = 0.000), BMI (p = 0.003), and gender (p = 0.019), which collectively explained 30% of the total variability. The mean UULEX completion time was 6% lower for the women than for the men.

Conclusions:

The present study was able to establish reference values for the UULEX test in healthy adults in Brazil. The values were influenced by age, gender, and BMI.

The combination of dynapenia and abdominal obesity as a risk factor for worse trajectories of IADL disability among older adults

Background/Objectives

The concept of dynapenic obesity has been gaining great attention recently. However, there is little epidemiological evidence demonstrating that dynapenic abdominal obese individuals have worse trajectories of disability than those with dynapenia and abdominal obesity alone. Our aim was to investigate whether dynapenia combined with abdominal obesity can result in worse trajectories of instrumental activities of daily living (IADL) among English and Brazilian older adults over eight and ten years of follow-up, respectively.

Methods

We used longitudinal data from 3374 participants from the English Longitudinal Study of Ageing (ELSA) and 1040 participants from the Brazilian Health, Well-being and Aging Study (SABE) who were free from disability as assessed by IADL at baseline. IADL disability was defined herein as a difficulty to perform the following: preparing meals, managing money, using transportation, shopping, using the telephone, house cleaning, washing clothes, and taking medications according to the Lawton IADL modified scale. The study population in each country was categorized into non-dynapenic/non-abdominal obese (reference group), abdominal obese, dynapenic and dynapenic abdominal obese according to their handgrip strength (<26 kg for men and <16 kg for women) and waist circumference (>102 cm for men and >88 cm for women). We used generalized linear mixed models with IADL as the outcome.

Results

The estimated change over time in IADL disability was significantly higher for participants with dynapenic abdominal obesity compared to those with neither condition in both cohorts (ELSA: 0.023, 95% CI = 0.012–0.034, p < 0.001; SABE: +0.065, 95% CI = 0.038–0.091, p < 0.001). Abdominal+obesity was also associated with changes over time in IADL disability (ELSA: +0.009, 95% CI = 0.002–0.015, p < 0.05; SABE: +0.021, 95% CI = 0.002–0.041, p < 0.05), which was not observed for dynapenia.

Conclusions

Abdominal obesity is an important risk factor for IADL decline but participants with dynapenic abdominal obesity had the highest rates of IADL decline over time among English and Brazilian older adults.

Effect of a randomised 12-week resistance training programme on muscular strength, cross-sectional area and muscle quality in women having undergone Roux-en-Y gastric bypass

The purpose of this study was to examine the effect of a 12-week resistance training programme on fat-free mass (FFM), muscle cross-sectional area, muscular strength and muscle quality in women who underwent Roux-en-Y gastric bypass surgery. Participants were 16 women (mean age = 44.9 ± 10.2 years) from bariatric surgical groups who were randomly assigned into either a control or an intervention group. Air displacement plethysmography measured FFM and magnetic resonance imaging measured quadriceps muscle cross-sectional area and whole thigh muscle cross-sectional area. Muscular strength and quality was assessed using an estimated 1-Repetition Maximum assessment. All measurements were collected twice, at baseline and at a 12-week follow-up. There were significantly greater improvements in leg press strength (mean differences = 55.4%, P < 0.001, Cohen's d = 2.4), leg extension strength (mean differences = 18.0%, P = 0.014, Cohen's d = 0.86) and leg press muscle quality (mean differences = 54.5%, P < 0.001, Cohen's d = 1.9) in the intervention group compared to the control group following the resistance training programme. The resistance training intervention significantly improved muscular strength and quality; however, it did not illicit changes in FFM or muscle cross-sectional area in women who underwent Roux-en-Y gastric bypass surgery.

Muscle Weakness Thresholds for Prediction of Diabetes in Adults

BACKGROUND

Despite the known links between weakness and early mortality, what remains to be fully understood is the extent to which strength preservation is associated with protection from cardiometabolic diseases, such as diabetes.

PURPOSE

The purposes of this study were to determine the association between muscle strength and diabetes among adults, and to identify age- and sex-specific thresholds of low strength for detection of risk.

METHODS

A population-representative sample of 4066 individuals, aged 20-85 years, was included from the combined 2011-2012 National Health and Nutrition Examination Survey (NHANES) data sets. Strength was assessed using a handheld dynamometer, and the single highest reading from either hand was normalized to body mass. A logistic regression model was used to assess the association between normalized grip strength and risk of diabetes, as determined by haemoglobin A1c levels ≥6.5 % (≥48 mmol/mol), while controlling for sociodemographic characteristics, anthropometric measures and television viewing time.

RESULTS

For every 0.05 decrement in normalized strength, there were 1.26 times increased adjusted odds for diabetes in men and women. Women were at lower odds of having diabetes (odds ratio 0.49; 95 % confidence interval 0.29-0.82). Age, waist circumference and lower income were also associated with diabetes. The optimal sex- and age-specific weakness thresholds to detect diabetes were 0.56, 0.50 and 0.45 for men at ages of 20-39, 40-59 and 60-80 years, respectively, and 0.42, 0.38 and 0.33 for women at ages of 20-39, 40-59 and 60-80 years, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

We present thresholds of strength that can be incorporated into a clinical setting for identifying adults who are at risk of developing diabetes and might benefit from lifestyle interventions to reduce risk.

Upper and Lower Body Muscle Power Increases After 3-Month Resistance Training in Overweight and Obese Men

This study evaluates the effect of 3 months resistance and aerobic training on muscle strength and power in 17 male overweight and obese men. Subjects underwent either a resistance or aerobic training for a period of 3 months (three sessions per week). Peak isometric force, rate of force development, peak power and height of countermovement and squat jumps, reactive strength index, and mean power in the concentric phase of bench presses were all assessed prior to and after completing the training program. Results identified a significant increase of mean power during both countermovement bench presses at 30 kg (18.6%, p = .021), 40 kg (14.6%, p = .033), and 50 kg (13.1%, p = .042) and concentric-only bench presses at 30 kg (19.6%, p = .017) and 40 kg (13.9%, p = .037) after the resistance training. There was also a significant increase in the height of the jump (12.8%, p = .013), peak power (10.1%, p = .026), and peak velocity (9.7%, p = .037) during the countermovement jump and height of the jump (11.8%, p = .019), peak power (9.6%, p = .032), and peak velocity (9.5%, p = .040) during the squat jump. There were no significant changes in the reactive strength index, peak force, and the rate of force development after the resistance training. The aerobic group failed to show any significant improvements in these parameters. It may be concluded that 3 months of resistance training without caloric restriction enhances upper and lower body muscle power in overweight and obese men.

Lower leg muscle density is independently associated with fall status in community-dwelling older adults

Muscle density is a risk factor for fractures in older adults; however, its association with falls is not well described. After adjusting for biologically relevant confounding factors, a unit decrease in muscle density was associated with a 17 % increase in odds of reporting a fall, independent of functional mobility.

INTRODUCTION

Falls are the leading cause of injury, disability, and fractures in older adults. Low muscle density (i.e., caused by muscle adiposity) and functional mobility have been identified as risk factors for incident disability and fractures in older adults; however, it is not known if these are also independently associated with falls. The purpose of this study was to explore the associations of muscle density and functional mobility with fall status.

METHODS

Cross-sectional observational study of 183 men and women aged 60-98 years. Descriptive data, including a 12-month fall recall, Timed Up and Go (TUG) test performance, lower leg muscle area, and density. Odds ratio (OR) of being a faller were calculated, adjusted for age, sex, body mass index, general health status, diabetes, and comorbidities.

RESULTS

Every mg/cm(3) increase in muscle density (mean 70.2, SD 2.6 mg/cm(3)) independently reduced the odds of being a faller by 19 % (OR 0.81 [95 % CI 0.67 to 0.97]), and every 1 s longer TUG test time (mean 9.8, SD 2.6 s) independently increased the odds by 17 % (OR 1.17 [95 % CI 1.01 to 1.37]). When both muscle density and TUG test time were included in the same model, only age (OR 0.93 [95 % CI 0.87 to 0.99]) and muscle density (OR 0.83 [95 % CI 0.69 to 0.99]) were independently associated with fall status.

CONCLUSIONS

Muscle density was associated with fall status, independent of functional mobility. Muscle density may compliment functional mobility tests as a biometric outcome for assessing fall risk in well-functioning older adults.

Grip Strength as a Marker of Hypertension and Diabetes in Healthy Weight Adults

INTRODUCTION

Muscle strength may play a role in cardiometabolic disease. We examined the relationship between hand grip strength and diabetes and hypertension in a sample of healthy weight adults.

METHODS

In 2015, we analyzed the National Health and Nutrition Examination Survey 2011-2012 for adults aged ≥20 years with healthy BMIs (between 18.5 and <25) and no history of cardiovascular disease (unweighted n=1,467; weighted n=61,587,139). Hand grip strength was assessed with a dynamometer. Diabetes was based on hemoglobin A1c level and reported diabetes diagnosis. Hypertension was based on measured blood pressure and reported hypertension diagnosis.

RESULTS

Individuals with undiagnosed diabetes compared with individuals without diabetes had lower grip strength (51.9 vs 69.8, p=0.0001), as did individuals with diagnosed diabetes compared with individuals without diabetes (61.7 vs 69.8, p=0.008). Mean grip strength was lower among individuals with undiagnosed hypertension compared with individuals without hypertension (63.5 vs 71.5, p=0.008) as well as among individuals with diagnosed hypertension compared with those without hypertension (60.8 vs 71.5, p<0.0001). In adjusted analyses controlling for age, sex, race, smoking status, and first-degree relative with disease, mean grip strength was lower for undiagnosed diabetes (β=-10.02, p<0.0001) and diagnosed diabetes (β=-8.21, p=0.03) compared with individuals without diabetes. In adjusted analyses, grip strength was lower among individuals with undiagnosed hypertension (β=-6.6, p=0.004) and diagnosed hypertension (β=-4.27, p=0.04) compared with individuals without hypertension.

CONCLUSIONS

Among healthy weight adults, combined grip strength is lower in individuals with diagnosed and undiagnosed diabetes and hypertension.

Diminished satellite cells and elevated adipogenic gene expression in muscle as caused by ovariectomy are averted by low-magnitude mechanical signals

Age-related degeneration of the musculoskeletal system, accelerated by menopause, is further complicated by increased systemic and muscular adiposity. The purpose of this study was to identify at the molecular, cellular, and tissue levels the impact of ovariectomy on adiposity and satellite cell populations in mice and whether mechanical signals could influence any outcomes. Eight-week-old C57BL/6 mice were ovariectomized, with one half subjected to low-intensity vibration (LIV; 0.3 g/90 Hz, 15 min/day, 5 day/wk; n = 10) for 6 wk and the others sham vibrated (OVX; n = 10). Data are compared with age-matched, intact controls (AC; n = 10). In vivo μCT analysis showed that OVX mice gained 43% total (P < 0.001) and 125% visceral adiposity (P < 0.001) compared with their baseline after 6 wk, whereas LIV gained only 21% total (P = 0.01) and 70% visceral adiposity (P < 0.01). Relative to AC, expression of adipogenic genes (PPARγ, FABP4, PPARδ, and FoxO1) was upregulated in OVX muscle (P < 0.05), whereas LIV reduced these levels (P < 0.05). Adipogenic gene expression was inversely related to the percentage of total and reserve satellite cell populations in the muscle, with both declining in OVX compared with AC (-21 and -28%, respectively, P < 0.01). LIV mitigated these declines (-11 and -17%, respectively). These results provide further evidence of the negative consequences of estrogen depletion and demonstrate that mechanical signals have the potential to interrupt subsequent adipogenic gene expression and satellite cell suppression, emphasizing the importance of physical signals in protecting musculoskeletal integrity and slowing the fat phenotype.

Effects of resistance training with and without caloric restriction on physical function and mobility in overweight and obese older adults: a randomized controlled trial

BACKGROUND

Resistance training (RT) improves muscle strength and overall physical function in older adults. RT may be particularly important in the obese elderly who have compromised muscle function. Whether caloric restriction (CR) acts synergistically with RT to enhance function is unknown.

OBJECTIVE

As the primary goal of the Improving Muscle for Functional Independence Trial (I'M FIT), we determined the effects of adding CR for weight loss on muscle and physical function responses to RT in older overweight and obese adults.

DESIGN

I'M FIT was a 5-mo trial in 126 older (65-79 y) overweight and obese men and women who were randomly assigned to a progressive, 3-d/wk, moderate-intensity RT intervention with a weight-loss intervention (RT+CR) or without a weight-loss intervention (RT). The primary outcome was maximal knee extensor strength; secondary outcomes were muscle power and quality, overall physical function, and total body and thigh compositions.

RESULTS

Body mass decreased in the RT+CR group but not in the RT group. Fat mass, percentage of fat, and all thigh fat volumes decreased in both groups, but only the RT+CR group lost lean mass. Adjusted postintervention body- and thigh-composition measures were all lower with RT+CR except intermuscular adipose tissue (IMAT). Knee strength, power, and quality and the 4-m gait speed increased similarly in both groups. Adjusted postintervention means for a 400-m walk time and self-reported disability were better with RT+CR with no group differences in other functional measures, including knee strength. Participants with a lower percentage of fat and IMAT at baseline exhibited a greater improvement in the 400-m walk and knee strength and power.

CONCLUSIONS

RT improved body composition (including reducing IMAT) and muscle strength and physical function in obese elderly, but those with higher initial adiposity experienced less improvement. The addition of CR during RT improves mobility and does not compromise other functional adaptations to RT. These findings support the incorporation of RT into obesity treatments for this population regardless of whether CR is part of the treatment. This trial was registered at clinicaltrials.gov as NCT01049698.

Community-dwelling female fallers have lower muscle density in their lower legs than non-fallers: evidence from the Saskatoon Canadian Multicentre Osteoporosis Study (CaMos) cohort

OBJECTIVES

Our objectives were to determine whether peripheral quantitative computed tomography (pQCT)-derived lower leg muscle density and area, and basic functional mobility differ between community-dwelling older women who do and do not report recent falls.

DESIGN

Matched case-control comparison.

SETTING

Academic biomedical imaging laboratory.

PARTICIPANTS

147 Women, 60 years or older (mean age 74.3 y, SD 7.7) recruited from a longitudinal, population-based cohort representing community-dwelling residents in the area of Saskatoon, Canada.

MEASUREMENTS

A cross-sectional pQCT scan of the non-dominant lower leg was acquired to determine muscle density and area. Basic functional mobility (Timed Up and Go Test [TUG]) and SF36 health status were also measured. Fallers (one or more falls) and non-fallers (no falls) were grouped according to a 12-month retrospective survey and matched on measured covariates.

RESULTS

The muscle density of fallers (n = 35) was a median of 2.1 mg/cm3 lower (P = 0.019, 95% C.I. -3.9 to -0.1) than non-fallers (n = 78) after matching and adjusting for age, body mass index, and SF36 general health scores. Muscle area and TUG did not differ between fallers and non-fallers.

CONCLUSIONS

Muscle density may serve as a physiological marker in the assessment of lower leg muscular health and fall risk in community-dwelling elderly women. These results are limited to our study population who were mostly Caucasian. Prospective studies are required for verification.

Identification of skeletal muscle mass depletion across age and BMI groups in health and disease--there is need for a unified definition

Although reduced skeletal muscle mass is a major predictor of impaired physical function and survival, it remains inconsistently diagnosed to a lack of standardized diagnostic approaches that is reflected by the variable combination of body composition indices and cutoffs. In this review, we summarized basic determinants of a normal lean mass (age, gender, fat mass, body region) and demonstrate limitations of different lean mass parameters as indices for skeletal muscle mass. A unique definition of lean mass depletion should be based on an indirect or direct measure of skeletal muscle mass normalized for height (fat-free mass index (FFMI), appendicular or lumbal skeletal muscle index (SMI)) in combination with fat mass. Age-specific reference values for FFMI or SMI are more advantageous because defining lean mass depletion on the basis of total FFMI or appendicular SMI could be misleading in the case of advanced age due to an increased contribution of connective tissue to lean mass. Mathematical modeling of a normal lean mass based on age, gender, fat mass, ethnicity and height can be used in the absence of risk-defined cutoffs to identify skeletal muscle mass depletion. This definition can be applied to identify different clinical phenotypes like sarcopenia, sarcopenic obesity or cachexia.

Difference in muscle quality over the adult life span and biological correlates in the Baltimore Longitudinal Study of Aging

OBJECTIVES

To examine differences in a proxy measure of muscle quality across the adult life span and explore potential mechanisms of muscle quality change through identification of cross-sectional correlates of muscle quality.

DESIGN

Cross-sectional study.

SETTING

Baltimore Longitudinal Study of Aging.

PARTICIPANTS

Seven hundred eighty-six individuals with a mean age of 66.3 (range 26-96) (N = 786). A sensitivity analysis was conducted in a subset of participants matched according to sex, muscle mass, and body size.

MEASUREMENTS

Muscle quality was operationalized as the ratio of knee-extension strength (isokinetic dynamometry) to thigh muscle cross-sectional area (computed tomography). Differences in muscle strength, muscle area, and muscle quality ratio with age were evaluated, and the association between the muscle quality ratio and measures reflecting domains of cognitive function, motor control, peripheral nerve function, adiposity, glucose homeostasis, and inflammation were assessed through multivariate regression analyses.

RESULTS

A linear relationship between age and muscle quality ratio was observed, suggesting a gradual decline in muscle quality over the adult life course. Associations were observed between muscle quality ratio and measures of adiposity, as well as peroneal nerve motor conduction velocity, finger tapping speed, and memory performance (P < .01). The association between muscle quality ratio and nerve conduction velocity was maintained after adjustment for anthropometric measurements (P < .05).

CONCLUSION

Muscle quality declines progressively with age over the adult life span and is affected by obesity and neurological factors. Studies are needed to clarify the mechanisms of these associations and their implications for functional outcomes.

Highlights from the functional single nucleotide polymorphisms associated with human muscle size and strength or FAMuSS study

The purpose of the Functional Single Nucleotide Polymorphisms Associated with Human Muscle Size and Strength study or FAMuSS was to identify genetic factors that dictated the response of health-related fitness phenotypes to resistance exercise training (RT). The phenotypes examined were baseline muscle strength and muscle, fat, and bone volume and their response to RT. FAMuSS participants were 1300 young (24 years), healthy men (42%) and women (58%) that were primarily of European-American descent. They were genotyped for ~500 polymorphisms and completed the Paffenbarger Physical Activity Questionnaire to assess energy expenditure and time spent in light, moderate, and vigorous intensity habitual physical activity and sitting. Subjects then performed a 12-week progressive, unilateral RT program of the nondominant arm with the dominant arm used as a comparison. Before and after RT, muscle strength was measured with the maximum voluntary contraction and one repetition maximum, while MRI measured muscle, fat, and bone volume. We will discuss the history of how FAMuSS originated, provide a brief overview of the FAMuSS methods, and summarize our major findings regarding genotype associations with muscle strength and size, body composition, cardiometabolic biomarkers, and physical activity.

Effect of mechanical and metabolic factors on motor function and fatigue in obese men and women: a cross-sectional study

BACKGROUND

Mechanical overload and poor quality of contractile elements related to metabolic abnormalities concur to motor disability of obesity. The independent contribution of these factors to motor dysfunction in obese individuals is scarcely defined.

AIM

Aim of the study is to test the hypothesis that metabolic factors may independently affect motor function in obesity.

METHODS

Leg maximum power output per unit body mass (W Mb), per unit fat-free mas (W FFM) and fatigue in daily functioning were assessed in 635 obese [body mass index (BMI)≥ 35 kg/m(2)] individuals (286 men, 349 women) aged 19-78 yr. The independent effects of age, BMI, insulin resistance and the five components of the metabolic syndrome on W Mb, W FFM and fatigue were evaluated by multivariate analysis.

RESULTS

A multiple regression analysis revealed that in both genders W Mb (denoting the individual's performance capability during anaerobic tasks) was independently reduced by age (p<0.001), BMI (p<0.05-0.001) and abnormalities of glucose metabolism (p<0.06-0.01), while W FFM (representing the muscle intrinsic anaerobic capability) was affected only by age (p<0.001) and glucose metabolism impairment (p<0.06-0.01). In both genders fatigue was increased by age (p<0.001) and BMI (p<0.05-0.01), but augmented by low levels of HDL-cholesterol in men only (p<0.05).

CONCLUSIONS

Besides depending on mechanical overload and age, low muscle power output in obese individuals was independently associated also with metabolic abnormalities related to impaired glucose homeostasis. Fatigue and performance, although similarly influenced by age and body mass excess, are affected by different metabolic factors.

Intramuscular adipose tissue attenuates gains in muscle quality in older adults at high risk for falling. A brief report

OBJECTIVES

To examine the influence of intramuscular adipose tissue (IMAT) on muscle quality (MQ) changes in older adults after 12 weeks of exercise training.

DESIGN

Prospective cohort design.

SETTING

Academic health science center clinical exercise facility.

PARTICIPANTS

70 older (mean age 73.4 ± 6.3 years) adults with a history of falls.

INTERVENTION

Resistance, endurance and balance exercise three times weekly for 12 weeks.

MEASUREMENTS

Quadriceps strength was determined by maximum voluntary isometric contraction. An MRI of the thigh was used to determine cross-sectional area of lean tissue and IMAT. MQ was calculated as the force per unit area of lean tissue. Individuals were stratified into tertiles (Low IMAT, Middle IMAT, High IMAT) based on pre-IMAT levels. Changes in MQ, lean and IMAT were compared across groups.

RESULTS

No significant changes in lean or IMAT occurred in any group with training. MQ increased only in the Low IMAT group. The Middle and High IMAT groups did not demonstrate a significant change in MQ following 12 weeks of training. Low IMAT, pre = 2.7 [0.6] post= 3.0 [0.6]; Middle IMAT, pre =2.54 [0.8] post =2.75 [0.7]; High IMAT, pre =2.6 [0.6] to post =2.5 [0.6].

CONCLUSION

High levels of thigh IMAT appear to blunt the adaptive MQ response to training. High levels of thigh IMAT may be a potential reason why some older adults do not change their MQ following training. Future research should confirm these results and determine why IMAT impairs MQ and the adaptive response to training in older adults.

Secondary muscle pathology and metabolic dysregulation in adults with cerebral palsy

Cerebral palsy (CP) is caused by an insult to or malformation of the developing brain which affects motor control centers and causes alterations in growth, development, and overall health throughout the life span. In addition to the disruption in development caused by the primary neurological insult, CP is associated with exaggerated sedentary behaviors and a hallmark accelerated progression of muscle pathology compared with typically developing children and adults. Factors such as excess adipose tissue deposition and altered partitioning, insulin resistance, and chronic inflammation may increase the severity of muscle pathology throughout adulthood and lead to cardiometabolic disease risk and/or early mortality. We describe a model of exaggerated health risk represented in adults with CP and discuss the mechanisms and secondary consequences associated with chronic sedentary behavior, obesity, aging, and muscle spasticity. Moreover, we highlight novel evidence that implicates aberrant inflammation in CP as a potential mechanism linking both metabolic and cognitive dysregulation in a cyclical pattern.