Twelve weeks' progressive resistance training combined with protein supplementation beyond habitual intakes increases upper leg lean tissue mass, muscle strength and extended gait speed in healthy older women

In the land of not-unhappiness: On the state-of-the-art of targeting aging and age-related diseases by biomedical research

The concept of the Land of Not-Unhappiness refers to the potential achievement of eliminating the pathologies of the aging process. To inform of how close we are to settling in the land, we summarize and review the achievements of research on anti-aging interventions over the last hundred years with a specific focus on strategies that slow down metabolism, compensate for aging-related losses, and target a broad range of age-related diseases. We critically evaluate the existing interventions labeled as "anti-aging," such as calorie restriction, exercise, stem cell administration, and senolytics, to provide a down-to-earth evaluation of their current applicability in counteracting aging. Throughout the text, we have maintained a light tone to make it accessible to non-experts in biogerontology, and provide a broad overview for those considering conducting studies, research, or seeking to understand the scientific basis of anti-aging medicine.

Comparative Efficacy of Different Protein Supplements on Muscle Mass, Strength, and Physical Indices of Sarcopenia among Community-Dwelling, Hospitalized or Institutionalized Older Adults Undergoing Resistance Training: A Network Meta-Analysis of Randomized Controlled Trials

Aging-related sarcopenia exerts harmful impacts on muscle mass, strength, and physical mobility. Protein supplementation has been demonstrated to augment efficacy of resistance training (RT) in elderly. This study compared the relative effects of different protein supplements on muscle mass, strength, and mobility outcomes in middle-aged and older individuals undergoing RT. A comprehensive search of online databases was performed to identify randomized controlled trials (RCTs) examining the efficacy of protein supplement plus RT in untrained community-dwelling adults, hospitalized, or institutionalized residents who suffered acute or chronic health conditions. Network meta-analysis (NMA) was performed using a frequentist method for all analyses. Treatment effects for main outcomes were expressed as standard mean difference (SMD) with 95% confidence interval (CI). We used the surface-under-the cumulative-ranking (SUCRA) scores to rank probabilities of effect estimation among all identified treatments. Meta-regression analyses were performed to identify any relevant moderator of the treatment efficacy and results were expressed as β with 95% credible interval (CrI). We finally included 78 RCTs (5272 participants) for analyses. Among the six protein sources identified in this NMA, namely whey, milk, casein, meat, soy, and peanut, whey supplement yielded the most effective treatments augmenting efficacy of RT on muscle mass (SMD = 1.29, 95% CI: 0.96, 1.62; SUCRA = 0.86), handgrip strength (SMD = 1.46, 95% CI: 0.92, 2.00; SUCRA = 0.85), and walking speed (SMD = 0.73, 95% CI: 0.39, 1.07; SUCRA = 0.84). Participant's health condition, sex, and supplementation dose were significant factors moderating the treatment efficacy on muscle mass (β = 0.74; 95% CrI: 0.22, 1.25), handgrip strength (β = -1.72; 95% CrI: -2.68, -0.77), and leg strength (β = 0.76; 95% CrI: 0.06, 1.47), respectively. Our findings suggest whey protein yields the optimal supplements to counter sarcopenia in older individuals undergoing RT.

Effects of resistance training and protein supplementation interventions on muscle volume and muscle function: sex differences in humans

PURPOSE

This review aimed to identify differences in the effects of co-intervention with resistance training (RT) and protein supplementation according to sex and provide meaningful information for future research on the development of exercise programs to improve muscle volume and muscle function.

METHODS

PubMed, Science Direct, and Google Scholar were searched to identify clinical and nonclinical studies that assessed the effects of RT in older adults with sarcopenia; these studies were published between 1990 and 2023. Cross-sectional and double-blind studies (randomized controlled trials, RCTs) were examined in this review.

RESULTS

The effects of parallel intervention with RT and protein supplementation on muscle volume and physical function were found to differ according to sex. Both males and females had improvements in muscle strength, muscle mass, and physical function after RT and protein supplementation; however, many studies found a greater increase in muscle volume and function in males than in females. Such difference may be due to differences in physiological characteristics between males and females.

CONCLUSION

Based on the findings of this review, the effects of combined intervention with RT and protein supplementation on muscle strength, muscle mass, and physical function to differ according to sex. Owing to these sex differences in the response and physiological characteristics caused by the parallel intervention of RT and protein supplementation, such differences must be considered to maximize the effects of RT and protein supplementation.

Effect Size of Dietary Supplementation and Physical Exercise Interventions for Sarcopenia in Middle-Aged Women

The purpose of this meta-analysis was to comprehensively analyze the relationship between intervention (di-etary supplementation and physical exercise), body composition, and physical activity capacity in middle-aged women with sarcopenia. A total of 19 studies published in the last ten years were selected. The overall effect size was small (0.29; 95% confidence interval: 0.195∼0.385). The Q value was 100.214 and the Higgin’s I² value was 82.038. Each study was found to be heterogeneous and there was no publication bias. The effect size was increased when the number of study partici-pants increased from 50 to 100 and when dietary vitamin D supplementation was combined with resistance exercise. Fur-thermore, the effect on physical activity capacity was higher than that on body composition. In conclusion, dietary vitamin D supplementation combined with resistance training had a positive impact on middle-aged women with sarcopenia.

The impact of resistance training on body composition, muscle strength, and functional fitness in older women (45-80 years): A systematic review (2010-2020)

As women age, they typically experience a progressive decrease in skeletal muscle mass and strength, which can lead to a decline in functional fitness and quality of life. Resistance training (RT) has the potential to attenuate these losses. Although well established for men, evidence regarding the benefits of RT for women is sparse and inconsistent: prior reviews include too few studies with women and do not adequately examine the interactive or additive impacts of workload, modalities, and nutritional supplements on outcomes such as muscle mass (MM), body composition (BC), muscle strength (MS), and functional fitness (FF). The purpose of this review is to identify these gaps. Thirty-eight papers published between 2010 and 2020 (in English) represent 2519 subjects (mean age = 66.89 ± 4.91 years). Intervention averages include 2 to 3 × 50 min sessions across 15 weeks with 7 exercises per session and 11 repetitions per set. Twelve studies (32%) examined the impact of RT plus dietary manipulation. MM, MS, and FF showed positive changes after RT. Adding RT to fitness regimens for peri- to postmenopausal women is likely to have positive benefits.

Daily Supplementation With Whey, Soy, or Whey-Soy Blended Protein for 6 Months Maintained Lean Muscle Mass and Physical Performance in Older Adults With Low Lean Mass

BACKGROUND

Few studies have investigated the effect of long-term protein supplementation alone on muscle health in older adults with low lean mass.

OBJECTIVE

To determine the effect of whey, soy or whey-soy blended protein supplementation on lean muscle mass and physical performance in older adults with low lean mass.

DESIGN

A 4-arm randomized controlled trial.

PARTICIPANTS/SETTING

Chinese older adults (n = 123, 65-79 years) with low lean mass (appendicular skeletal muscle index < 7.0 kg/m² in men and < 5.4 kg/m² in women) living in the urban area of Guangzhou participated between October 2015 and June 2016.

INTERVENTION

Participants were randomly assigned to receive approximately 16 g/d of whey, soy, or whey-soy blend protein or maintained habitual diets in control group for 6 months.

MAIN OUTCOME MEASURES

Lean mass, handgrip strength, and physical performance (gait speed, chair stand test, and Short Physical Performance Battery) were assessed at baseline and 6 months.

STATISTICAL ANALYSES

Two-way analysis of variance with the main effects of treatment and time and treatment × time interaction and analysis of covariance was used to determine differences in outcomes.

RESULTS

Appendicular skeletal muscle index, lean mass, percent lean mass in legs and appendicular areas, gait speed, and Short Physical Performance Battery score were maintained in the treatment groups and decreased in the control group, resulting in significant reduction in these variables from baseline in the control compared with treatment groups (all P < .01; percent differences between treatment and control groups ranged from 80% to 156%). The chair stand test time at month 6 decreased from baseline in the treatment groups and increased in the control group, resulting in a significant increase in the control compared with treatment groups (all P < .01; percent differences between treatment and control groups ranged from 132% to 155%). Handgrip strength remained unchanged. There were no significant differences in outcomes among treatment groups.

CONCLUSIONS

Supplementation with whey, soy, or whey-soy blended protein for 6 months equally maintained lean muscle mass and physical performance in older adults with low lean mass.

A 4-week exercise and protein program improves muscle mass and physical functioning in older adults - A pilot study

BACKGROUND

Prehabilitation might attenuate common surgery-induced losses in muscle mass and physical performance. Beneficial effects of physical exercise with protein supplementation have been reported in older adults, but typically after an intervention of at least 12 weeks. The time-window for pre-surgery training is often limited to around 30 days, and it is not known if it is possible to achieve comparable results in such a short time window.

OBJECTIVES

The aim of this study was to pilot-test the effectiveness of a controlled four-week combined exercise and protein supplementation program on skeletal muscle-related outcomes in a Dutch older adult population.

DESIGN

This study was a one-armed pilot trial.

PARTICIPANTS

Seventeen older men and women, aged 55-75y, not scheduled for surgery.

INTERVENTION

A 4-week intervention program consisting of a twice-weekly supervised resistance and high-intensity aerobic exercise training of 75 min, combined with daily protein supplementation (2 doses of 15.5 g/day at breakfast and lunch).

MEASUREMENT

After two and four weeks, isometric quadriceps maximal voluntary contraction (MVC) was assessed via Biodex and quadriceps cross-sectional area (CSA) via magnetic resonance imaging. Other outcome measures were handgrip strength, chair rise time and maximal aerobic capacity (VO₂-max), as assessed from a submaximal exercise test.

RESULTS

Compliance to the supervised training sessions (99.3%) and the protein supplementation (97%) was very high. The 4-week exercise and protein program led to an increase in quadriceps CSA of 2.3 ± 0.7 cm² (P = 0.008) in the dominant leg and 3.2 ± 0.7 cm² (P < 0.001) in the non-dominant leg. Isometric quadriceps MVC increased in the dominant leg (Δ14 ± 4 Nm, P = 0.001) and in the non-dominant leg (Δ17 ± 5 Nm, P = 0.003). Chair rise test time improved with -3.8 ± 0.5 s (P < 0.0001), and VO₂-max improved with 3.3 ± 1.1 ml/min/kg (P = 0.014). We observed no changes in body weight and handgrip strength.

CONCLUSION

A 4-week exercise and protein intervention led to improvements in muscle-related outcomes in older adults with low levels of physical activity.

Effect of lean red meat combined with a multicomponent exercise program on muscle and cognitive function in older adults: a 6-month randomized controlled trial

BACKGROUND

Exercise and increased dietary protein have been linked to improved muscle and cognitive health, but the combination may be more effective.

OBJECTIVE

In this study performed in community-dwelling older adults undergoing a 3-d/wk resistance-based exercise training program, we investigated whether those who consumed lean red meat compared to carbohydrates on the 3 training days per wk would experience greater exercise-induced improvements in total body and leg lean mass (LM), muscle strength, and executive function (multiple primary outcomes), as well as muscle size and density, functional performance, cognition, inflammatory and neurotrophic markers, blood pressure, and lipid concentrations.

DESIGN

In a 24-wk, 2-arm parallel randomized controlled trial, 154 adults aged ≥65 y participated in a multicomponent 3-d/wk resistance-based exercise program with random allocation to either a lean red meat group (two 80-g servings of cooked red meat), the exercise plus lean red meat (Ex + Meat) group (n = 77) or a control group receiving carbohydrates in the form of one-half cup (approximately 225 g cooked weight) of rice or pasta or 1 medium potato, the exercise plus carbohydrate control (C + Ex) group (n = 77), on the training days.

RESULTS

Exercise-induced improvements (mean within group changes) did not significantly differ between groups for the primary outcomes of total body LM (0.6 to 0.8 kg), leg LM (0.1 to 0.2 kg), thigh muscle cross-sectional area (3.7% to 4.9%), leg and back muscle strength (26% to 40%), and executive function (z-score SD: 0.33 to 0.39), nor the secondary outcomes of global cognition function (0.17 to 0.23 SD), fat mass (-0.65 to -0.75 kg), physical function measures (sit-to-stand, both 15%; 4-square step test, 2% to 7%), or systolic blood pressure (-3.2 to -4.1 mm Hg). The Ex + Meat group experienced greater improvements than the C + Ex in arm LM (0.07 kg; 95% CI: 0.01, 0.14; P = 0.029), gait speed (0.05 m/s; 95% CI: 0.00, 0.11; P = 0.042), muscle density (1.0%; 95% CI: 0.2, 1.9; P = 0.015), and appendicular LM in the per-protocol analysis (0.21 kg; 95% CI: 0.02, 0.40; P = 0.03). The C + Ex group had greater net improvements in working memory/learning after 12 wk (SD: 0.24; 95% CI: 0.05, 0.43; P = 0.011) and 24 wk (SD: 0.27; 95% CI: 0.06, 0.49; P = 0.007). Inflammatory and neurotrophic markers did not change in either group.

CONCLUSION

In healthy community-dwelling older adults undertaking resistance-based exercise training 3-d/wk, participants who consumed lean red meat in line with current Australian dietary recommendations did not experience any significant additional benefits in the primary outcome measures of muscle mass, strength, or cognitive function compared to participants consuming carbohydrates.This trial is registered with the Australian and New Zealand Clinical Trials Registry as ACTRN12613001153707.

Sarcopenia: Current treatments and new regenerative therapeutic approaches

Sarcopenia is characterized by loss of muscle and reduction in muscle strength that contributes to higher mortality rate and increased incidence of fall and hospitalization in the elderly. Mitochondria dysfunction and age-associated inflammation in muscle are two of the main attributors to sarcopenia progression. Recent clinical trials on sarcopenia therapies such as physical exercise, nutraceutical, and pharmaceutical interventions have revealed that exercise is the only effective strategy shown to alleviate sarcopenia. Unlike nutraceutical and pharmaceutical interventions that showed controversial results in sarcopenia alleviation, exercise was found to restore mitochondria homeostasis and dampen inflammatory responses via a complex exchange of myokines and osteokines signalling between muscle and bone. However, as exercise have limited benefit to immobile patients, the use of stem cells and their secretome are being suggested to be novel therapeutics that can be catered to a larger patient population owing to their mitochondria restoration effects and immune modulatory abilities. As such, we reviewed the potential pros and cons associated with various stem cell types/secretome in sarcopenia treatment and the regulatory and production barriers that need to be overcome to translate such novel therapeutic agents into bedside application.

Translational potential: This review summarizes the causes underlying sarcopenia from the perspective of mitochondria dysfunction and age-associated inflammation, and the progress of clinical trials for the treatment of sarcopenia. We also propose therapeutic potential of stem cell therapy and bioactive secretome for sarcopenia.

Age-Group Differences in the Performance of Selected Tests of Physical Function and Association With Lower Extremity Strength

BACKGROUND AND PURPOSE

It is not known whether short functional performance tests used in aging research are appropriate for use in healthy older adults. The purpose of this study was to investigate age-group differences (sixth decade vs seventh decade) in selected functional performance tests and the association between lower extremity strength and functional performance.

METHODS

One hundred fifty-nine (18.2% [n = 29] male) healthy older adults (mean (standard deviation) age 60.4 (5.3) years), adults were recruited from the University of Limerick Campus Community. Knee extensor (KE) peak torque (PT) was assessed from a maximal voluntary isometric contraction. Subsequently, participants completed 10-m maximal and habitual gait speed tests, 5 repetition and 30-second chair rise tests, and a 900-m gait speed test.

RESULTS AND DISCUSSION

There was no difference in 10-m gait speed between those in the sixth and seventh decades (P > .05). Compared with the sixth decade, those in the seventh decade required an extra 39 seconds to complete 900 m, an extra 0.6 seconds to complete 5 chair rises and performed 2 fewer chair rises in a 30-second time period (P < .05). All tests had a weak association with KE strength (r = 0.226-0.360; P < .05), except for 900-m gait speed that had a moderate association (r = -0.537; P < .001). Our findings suggest that gait speed tests of 10 m or less cannot detect age-related difference in functional capacity when used in healthy older adults.

CONCLUSION

Extended physical performance tests should be used in aging research on healthy older adults.

Health Benefits of Whey or Colostrum Supplementation in Adults ≥35 Years; a Systematic Review

Food-health claims are an important method of translating nutrition research to consumers. Whey and colostrum are thought to exert health benefits to adults, but it is unclear what measurable, objective health benefits they impart. This review aimed to identify the objective health benefits of bovine whey or colostrum-based beverages to healthy adults aged ≥35 years to substantiate a food-health claim. Seven databases were systematically searched. Eligible articles were RCTs that involved healthy adults aged ≥35 years, consuming whey or colostrum in beverage form and measuring objective health markers. Quality assessment and data extraction was conducted in duplicate. The searches identified 9943 papers and 16 were included in this review; 13 studies, reported across 15 papers, related to whey, one study to colostrum. The outcomes identified were body composition, bone mineral density, biochemical markers, such as blood glucose and lipids, and muscle strength and synthesis. Heterogeneous outcomes, high risk of bias and inconsistent findings resulted in inconclusive evidence to substantiate a food-health claim. Clearer reporting and consensus on a minimum set of objective measures would allow for more robust recommendations regarding food-health claims. Protecting consumers from misleading health claims will require collaboration between regulators, researchers, and the food industry.

Johnson M. Pain and Function in the Runner a Ten (din) uous Link

A male runner (30 years old; 10-km time: 33 min, 46 s) had been running with suspected insertional Achilles tendinopathy (AT) for ~2 years when the pain reached a threshold that prevented running. Diagnostic ultrasound (US), prior to a high-volume stripping injection, confirmed right-sided medial insertional AT. The athlete failed to respond to injection therapy and ceased running for a period of 5 weeks. At the beginning of this period, the runner completed the Victoria institute of sports assessment–Achilles questionnaire (VISA-A), the foot and ankle disability index (FADI), and FADI sport prior to undergoing an assessment of bi-lateral gastrocnemius medialis (GM) muscle architecture (muscle thickness (MT) and pennation angle (PA); US), muscle contractile properties (maximal muscle displacement (Dm) and contraction time (Tc); Tensiomyography (TMG)) and calf endurance (40 raises/min). VISA-A and FADI scores were 59%/100% and 102/136 respectively. Compared to the left leg, the right GM had a lower MT (1.60 cm vs. 1.74 cm), a similar PA (22.0° vs. 21.0°), a lower Dm (1.2 mm vs. 2.0 mm) and Tc (16.5 ms vs. 17.7 ms). Calf endurance was higher in the right leg compared to the left (48 vs. 43 raises). The athlete began a metronome-guided (15 BPM), 12-week progressive eccentric training protocol using a weighted vest (1.5 kg increments per week), while receiving six sessions of shockwave therapy concurrently (within 5 weeks). On returning to running, the athlete kept daily pain (Numeric Rating Scale; NRS) and running scores (miles*rate of perceived exertion (RPE)). Foot and ankle function improved according to scores recorded on the VISA-A (59% vs. 97%) and FADI (102 vs. 127/136). Improvements in MT (1.60 cm vs. 1.76 cm) and PA (22.0° vs. 24.8°) were recorded via US. Improvements in Dm (1.15 mm vs. 1.69 mm) and Tc (16.5 ms vs. 15.4 ms) were recorded via TMG. Calf endurance was lower in both legs and the asymmetry between legs remained (L: 31, R: 34). Pain intensity (mean weekly NRS scores) decreased between week 1 and week 12 (6.6 vs. 2.9), while running scores increased (20 vs. 38) during the same period. The program was maintained up to week 16 at which point mean weekly NRS was 2.2 and running score was 47.

A new approach to the classification of muscle health: preliminary investigations

OBJECTIVE

Upper leg skeletal or lean tissue mass (LTM), strength and muscle quality have emerged as time-sensitive indices of muscular health. The aim of this study was to generate a comparative data set based on these indices, in healthy young (n  =  30, 29.0  ±  3.0 y old) and older (n  =  32, 58.7  ±  2.8 years old) adults, in order to evaluate their construct validity in establishing cut-points for muscle health.

APPROACH

Whole body and upper leg LTM was obtained (iDXATM; GE Healthcare, Madison, WI) prior to the assessment of maximal voluntary isometric torque of the knee extensors and flexors (Cybex Isokinetic Dynamometer; Humac Norm, USA).

MAIN RESULTS

Peak isometric upper leg torque showed the greatest age-related difference (-29.0%), followed by muscle quality (-19.1%) and upper leg LTM (-9.8%).

SIGNIFICANCE

Cut-points based on Z and T-scores generated from the young adult mean suggest muscle quality demonstrates the greatest construct validity toward the aim of classifying the muscular health of adults. Data generated from large, representative and sex-specific samples are required to adequately classify the muscular health of adults.

Neuromuscular Attributes Associated With Lower Extremity Mobility Among Community-Dwelling Older Adults

BACKGROUND

The Short Physical Performance Battery (SPPB) is advocated as a screening tool in geriatric care for predicting future disability. We aimed to identify the leg neuromuscular attributes to be targeted in rehabilitative care among older adults with poor SPPB scores.

METHODS

Boston Rehabilitative Impairment Study of the Elderly (Boston RISE) participants (n = 430) underwent assessment of neuromuscular attributes (leg strength, leg velocity, trunk extensor endurance, knee flexion range of motion [ROM], ankle ROM, and foot sensation). Linear regression models examined association between each neuromuscular attribute and SPPB, adjusting for age, race, gender, comorbidity, body mass index, depression, cognition, and other neuromuscular attributes.

RESULTS

Participants with 1 SD unit higher leg strength, leg velocity, and trunk extensor endurance had 0.52, 0.30, and 0.52 points higher SPPB total score. Participants with ankle ROM impairment and foot sensory loss had 0.43 and 0.57 lower SPPB total score compared with those without these. Leg strength and trunk extensor endurance were associated with balance; leg velocity, trunk extensor endurance, and ankle ROM were associated with gait speed; and strength, trunk extensor endurance, knee ROM, and feet sensation were associated with chair stand score. Neuromuscular attributes, along with covariates, explained 40.4% of the variance in the total SPPB score, a substantial increase over the 22.7% variance explained by covariates alone.

CONCLUSIONS

Neuromuscular attributes affect mobility performance in older patients as measured by the SPPB. Specific impairments are associated with poor performance in specific component scores. Assessment of the SPPB components and rehabilitation of associated impairments may help improve the functional performance among older adults.

The effects of a combined bodyweight-based and elastic bands resistance training, with or without protein supplementation, on muscle mass, signaling and heat shock response in healthy older people

This investigation sought to determine the effects of twelve weeks of resistance exercise training in addition to protein supplementation on body composition, markers of muscle atrophy/hypertrophy and heat shock response (HSR) in healthy older adults. Thirty-eight healthy sedentary participants (M/F, 18/20; age, 63.5 ± 4.4 y) were randomly assigned to four groups: I) PLACEBO: no training, receiving placebo sachets; II) NUTRITION: no training, receiving protein supplementation sachets; III) EXERCISE PLACEBO: training, placebo sachets and IV) EXERCISE NUTRITION: training, receiving protein sachets. The resistance training (using bodyweight and elastic bands) consisted of 45 min supervised training sessions, 3×/week. Participants from both exercise groups increased their total lean body mass (from 48.4 ± 8.7 to 49.2 ± 8.7 kg and from 44.9 ± 7.8 to 45.9 ± 8.1 kg, average of gain ~0.8 and 1 kg, placebo and nutrition respectively) and improved results in physical tests. Exercise nutrition group also reduced their body fat (from 34.8 ± 7.3 to 32.9 ± 7.4%), increased the expression of proteins/gene involved on the HSR, S6 and eEF2, while FOXO3 and Murf1 were reduced. Expression of MHC-I was reduced in both exercise groups while MHC-IIa increased, with no effect of protein supplementation alone. Body-weight and elastic bands based resistance exercise prompted, in healthy older people, improvements in body composition and muscle function. When protein supplementation was added to the people engaged in resistance training, improvements in fat mass and changes in skeletal muscle signaling were detected, favoring protein synthesis pathways and the protective heat shock response.

Muscle strength and size are associated with motor unit connectivity in aged mice

In older adults, the loss of muscle strength (dynapenia) and the loss of muscle mass (sarcopenia) are important contributors to the loss of physical function. We sought to investigate dynapenia, sarcopenia, and the loss of motor unit function in aging mice. C57BL/6J mice were analyzed with cross-sectional (males: 3 vs. 27 months; males and females: 8 vs. 12 vs. 20 months) and longitudinal studies (males: 10-25 months) using in vivo electrophysiological measures of motor unit connectivity (triceps surae compound muscle action potential and motor unit number estimation), in vivo measures of plantar flexion torque, magnetic resonance imaging of hind limb muscle volume, and grip strength. Compound muscle action potential amplitude, motor unit number estimation, and plantar flexion torque were decreased at 20 months. In contrast, grip strength was reduced at 24 months. Motor unit number estimates correlated with muscle torque and hind limb muscle volume. Our results demonstrate that the loss of motor unit connectivity is an early finding in aging male and female mice and that muscle size and contractility are both associated with motor unit number.

Myocardial adaption to HI(R)T in previously untrained men with a randomized, longitudinal cardiac MR imaging study (Physical adaptions in Untrained on Strength and Heart trial, PUSH-trial)

Objective

Although musculoskeletal effects in resistance training are well described, little is known about structural and functional cardiac adaption in formerly untrained subjects. We prospectively evaluated whether short term high intensity (resistance) training (HI(R)T) induces detectable morphologic cardiac changes in previously untrained men in a randomized controlled magnetic resonance imaging (MRI) study.

Materials and methods

80 untrained middle-aged men were randomly assigned to a HI(R)T-group (n = 40; 43.5±5.9 years) or an inactive control group (n = 40; 42.0±6.3 years). HI(R)T comprised 22 weeks of training focusing on a single-set to failure protocol in 2–3 sessions/week, each with 10–13 exercises addressing main muscle groups. Repetitions were decreased from 8–10 to 3–5 during study period. Before and after HI(R)T all subjects underwent physiologic examination and cardiac MRI (cine imaging, tagging).

Results

Indexed left (LV) and right ventricular (RV) volume (LV: 76.8±15.6 to 78.7±14.8 ml/m²; RV: 77.0±15.5 to 78.7±15.1 ml/m²) and mass (LV: 55.5±9.7 to 57.0±8.8 g/m²; RV: 14.6±3.0 to 15.0±2.9 g/m²) significantly increased with HI(R)T (all p<0.001). Mean LV and RV remodeling indices of HI(R)T-group did not alter with training (0.73g/mL and 0.19g/mL, respectively [p = 0.96 and p = 0.87]), indicating balanced cardiac adaption. Indexed LV (48.4±11.1 to 50.8±11.0 ml/m²) and RV (48.5±11.0 to 50.6±10.7 ml/m²) stroke volume significantly increased with HI(R)T (p<0.001). Myocardial strain and strain rates did not change following resistance exercise. Left atrial volume at end systole slightly increased after HI(R)T (36.2±7.9 to 37.0±8.4 ml/m², p = 0.411), the ratio to end-diastolic LV volume at baseline and post-training was unchanged (0.47 vs. 0.47, p = 0.79).

Conclusion

22 weeks of HI(R)T lead to measurable, physiological changes in cardiac atrial and ventricular morphologic characteristics and function in previously untrained men.

Trial regristration

The PUSH-trial is registered at the US National Institutes of Health (ClinicalTrials.gov), NCT01766791.

Measurement of muscle health in aging

Muscle health is a critical component in the struggle against physical frailty and the efforts to maintain metabolic health until the limit of chronological age. Consensus opinion is to evaluate muscle health in terms of muscle mass, strength and functional capability. There has been considerable variability in the components of muscle health which have been investigated in addition to variability in the tools of assessment and protocol for measurement. This is in stark contrast to the validated measurement of bone health across the adult life span. The purpose of this review was to identify indices of muscle mass, strength and functional capability most responsive to change with ageing and where possible to provide an estimate of the rate of change. We suggest lean tissue mass (LTM) or skeletal muscle (SM) is best evaluated from the thigh region due to its greater responsiveness to ageing compared to the whole body. The anterior compartment of the thigh region undergoes a preferential age-related decline in SM and force generating capacity. Therefore, we suggest that knee extensor torque is measured to represent the force generating capacity of the thigh and subsequently, to express muscle quality (strength per unit tissue). Finally, we suggest measures of functional capability which allow participants perform to a greater maximum are most appropriate to track age-related difference in functional capacity across the adult lifespan. This is due to their ability encompass a broad spectrum of abilities. This review suggests indices of muscular health for which reference ranges can be generated across the lifespan.

Muscle strength can better differentiate between gradations of functional performance than muscle quality in healthy 50-70y women

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Muscle strength is a better predictor of functional performance than muscle quality.

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Extended gait speed is a functionally relevant measure in healthy 50–70 y women.

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Healthy adults need functional assessments that allow performance toward maximum.

Objective

It is not known which laboratory indices of muscle mass, strength or quality can distinguish functional performance in healthy middle aged women. The aim of this study was to (a) examine the association between upper leg lean tissue mass, knee extensor strength, muscle quality (strength per unit lean tissue mass) and functional performance and (b) to determine the utility of tertiles of muscle strength and muscle quality to distinguish gradations of functional capacity in healthy 50–70 y women.

Methods

Using a cross-sectional study design, one hundred and twenty-eight healthy 50–70 y women (mean age: 60.4, SD = 5.1 y) underwent body composition assessment (dual X-ray absorptiometry) and performed maximal voluntary isometric contractions of the knee extensors (Con-Trex Dynamometer). Functional performance was assessed using a 5 repetition and 30 s chair rise test and 900 m gait speed test.

Results

Ordered by muscle strength or muscle quality, those in the highest tertile (T1) demonstrated greater functional performance than those in lowest tertile (T3). There was no association between upper leg lean tissue mass and functional performance (r = ≤0.06). Muscle strength explained a greater proportion of the variance in all functional performance measures relative to muscle quality (R² = 0.13–0.36 vs. R² = 0.11–0.16).

Conclusion

Upper leg lean tissue mass is not associated with physical performance in healthy 50–70 y women. These results suggest strength relative to the body mass being accelerated distinguishes gradations in functional performance better than muscle quality healthy 50–70 y women.

Resistance wheel exercise from mid-life has minimal effect on sciatic nerves from old mice in which sarcopenia was prevented

The ability of resistance exercise, initiated from mid-life, to prevent age-related changes in old sciatic nerves, was investigated in male and female C57BL/6J mice. Aging is associated with cellular changes in old sciatic nerves and also loss of skeletal muscle mass and function (sarcopenia). Mature adult mice aged 15 months (M) were subjected to increasing voluntary resistance wheel exercise (RWE) over a period of 8 M until 23 M of age. This prevented sarcopenia in the old 23 M aged male and female mice. Nerves of control sedentary (SED) males at 3, 15 and 23 M of age, showed a decrease in the myelinated axon numbers at 15 and 23 M, a decreased g-ratio and a significantly increased proportion of myelinated nerves containing electron-dense aggregates at 23 M. Myelinated axon and nerve diameter, and axonal area, were increased at 15 M compared with 3 and 23 M. Exercise increased myelinated nerve profiles containing aggregates at 23 M. S100 protein, detected with immunoblotting was increased in sciatic nerves of 23 M old SED females, but not males, compared with 15 M, with no effect of exercise. Other neuronal proteins showed no significant alterations with age, gender or exercise. Overall the RWE had no cellular impact on the aging nerves, apart from an increased number of old nerves containing aggregates. Thus the relationship between cellular changes in aging nerves, and their sustained capacity for stimulation of old skeletal muscles to help maintain healthy muscle mass in response to exercise remains unclear.