Low muscle strength is an important heritable indicator of poor health linked to morbidity and mortality in older people. In a genome-wide association study meta-analysis of 256,523 Europeans aged 60 ...years and over from 22 cohorts we identify 15 loci associated with muscle weakness (European Working Group on Sarcopenia in Older People definition: n = 48,596 cases, 18.9% of total), including 12 loci not implicated in previous analyses of continuous measures of grip strength. Loci include genes reportedly involved in autoimmune disease (HLA-DQA1 p = 4 × 10
), arthritis (GDF5 p = 4 × 10
), cell cycle control and cancer protection, regulation of transcription, and others involved in the development and maintenance of the musculoskeletal system. Using Mendelian randomization we report possible overlapping causal pathways, including diabetes susceptibility, haematological parameters, and the immune system. We conclude that muscle weakness in older adults has distinct mechanisms from continuous strength, including several pathways considered to be hallmarks of ageing.
Sarcopenia is a skeletal muscle disorder that commonly occurs with advancing age as well as with a number of long-term conditions. Recognition in clinical practice is relatively recent but important ...because of the association between sarcopenia and a range of adverse effects on health including impaired mobility, increased morbidity and mortality. Originally characterised as loss of muscle mass, the definition has evolved to focus on loss of skeletal muscle function, particularly strength, through a number of international definitions such as that of the European Working Group on Sarcopenia in Older People most recently revised in 2019. Progress in the decades ahead is likely to be seen with regard to use of routine health data, prescription of resistance exercise, translation of biology and epidemiology into first in man studies for new treatments, and focus on sarcopenia in low and middle-income countries. Immediate next steps include the newly formed Global Leadership Initiative on Sarcopenia to develop international consensus on definition and diagnosis.
PurposeTo investigate early structural and mechanical predictors of plantarflexor muscle strength and the magnitude of Achilles tendon (AT) nonuniform displacement at 6 and 12 months after AT ...rupture.MethodsThirty‐five participants (28 males and 7 females; mean ± SD age 41.7 ± 11.1 years) were assessed for isometric plantarflexion maximal voluntary contraction (MVC) and AT nonuniformity at 6 and 12 months after rupture. Structural and mechanical AT and plantarflexor muscle properties were measured at 2 months. Limb asymmetry index (LSI) was calculated for all variables. Multiple linear regression was used with the 6 and 12 month MVC LSI and 12 month AT nonuniformity LSI as dependent variables and AT and plantarflexor muscle properties at 2 months as independent variables. The level of pre‐ and post‐injury sports participation was inquired using Tegner score at 2 and 12 months (scale 0–10, 10 = best possible score). Subjective perception of recovery was assessed with Achilles tendon total rupture score (ATRS) at 12 months (scale 0–100, 100=best possible score).ResultsAchilles tendon resting angle (ATRA) symmetry at 2 months predicted MVC symmetry at 6 and 12 months after rupture (β = 2.530, 95% CI 1.041–4.018, adjusted R2 = 0.416, p = 0.002; β = 1.659, 95% CI 0.330–2.988, adjusted R2 = 0.418, p = 0.016, respectively). At 12 months, participants had recovered their pre‐injury level of sports participation (Tegner 6 ± 2 points). The median (IQR) ATRS score was 92 (7) points at 12 months.ConclusionGreater asymmetry of ATRA in the early recovery phase may be a predictor of plantarflexor muscle strength deficits up to 1 year after rupture.Trial Registration: This research is a part of “nonoperative treatment of Achilles tendon rupture in Central Finland: a prospective cohort study” that has been registered in ClinicalTrials.gov (NCT03704532)
Maximal isometric muscle strength (MIMS) assessment is a key component of physiotherapists' work. Hand-held dynamometry (HHD) is a simple and quick method to obtain quantified MIMS values that have ...been shown to be valid, reliable, and more responsive than manual muscle testing. However, the lack of MIMS reference values for several muscle groups in healthy adults with well-known psychometric properties limits the use and the interpretation of these measures obtained with HHD in clinic.
To determine the intra- and inter-rater reliability, standard error of measurement (SEM) and minimal detectable change (MDC) of MIMS torque values obtained with HHD.
Intra and Inter-rater Reliability Study. The MIMS torque of 17 muscle groups was assessed by two independent raters at three different times in 30 healthy adults using a standardized HHD protocol using the MEDup™ (Atlas Medic, Québec, Canada). Participants were excluded if they presented any of the following criteria: 1) participation in sport at a competitive level; 2) degenerative or neuromusculoskeletal disease that could affect torque measurements; 3) traumatic experience or disease in the previous years that could affect their muscle function; and 4) use of medication that could impact muscle strength (e.g., muscle relaxants, analgesics, opioids) at the time of the evaluation. Intra- and inter-rater reliability were determined using two-way mixed (intra) and random effects (inter) absolute agreement intraclass correlation coefficients (ICC: 95% confidence interval) models. SEM and MDC were calculated from these data.
Intra- and inter-rater reliability were excellent with ICC (95% confidence interval) varying from 0.90 to 0.99 (0.85-0.99) and 0.89 to 0.99 (0.55-0.995), respectively. Absolute SEM and MDC for intra-rater reliability ranged from 0.14 to 3.20 Nm and 0.38 to 8.87 Nm, respectively, and from 0.17 to 5.80 Nm and 0.47 to 16.06 Nm for inter-rater reliability, respectively.
The excellent reliability obtained in this study suggest that the use of such a standardized HHD protocol is a method of choice for MIMS torque measurements in both clinical and research settings. And the identification of the now known metrological qualities of such a protocol should encourage and promote the optimal use of manual dynamometry.
Fragala, MS, Cadore, EL, Dorgo, S, Izquierdo, M, Kraemer, WJ, Peterson, MD, and Ryan, ED. Resistance training for older adults: position statement from the national strength and conditioning ...association. J Strength Cond Res 33(8): 2019-2052, 2019-Aging, even in the absence of chronic disease, is associated with a variety of biological changes that can contribute to decreases in skeletal muscle mass, strength, and function. Such losses decrease physiologic resilience and increase vulnerability to catastrophic events. As such, strategies for both prevention and treatment are necessary for the health and well-being of older adults. The purpose of this Position Statement is to provide an overview of the current and relevant literature and provide evidence-based recommendations for resistance training for older adults. As presented in this Position Statement, current research has demonstrated that countering muscle disuse through resistance training is a powerful intervention to combat the loss of muscle strength and muscle mass, physiological vulnerability, and their debilitating consequences on physical functioning, mobility, independence, chronic disease management, psychological well-being, quality of life, and healthy life expectancy. This Position Statement provides evidence to support recommendations for successful resistance training in older adults related to 4 parts: (a) program design variables, (b) physiological adaptations, (c) functional benefits, and (d) considerations for frailty, sarcopenia, and other chronic conditions. The goal of this Position Statement is to a) help foster a more unified and holistic approach to resistance training for older adults, b) promote the health and functional benefits of resistance training for older adults, and c) prevent or minimize fears and other barriers to implementation of resistance training programs for older adults.
ABSTRACT
Introduction
The purpose of this study was to determine the impact of an in‐home expiratory muscle strength training (EMST) program on pulmonary, swallow, and cough function in individuals ...with amyotrophic lateral sclerosis (ALS).
Methods
EMST was tested in a prospective, single‐center, double‐blind, randomized, controlled trial of 48 ALS individuals who completed 8 weeks of either active EMST (n = 24) or sham EMST (n = 24). The primary outcome to assess treatment efficacy was change in maximum expiratory pressure (MEP). Secondary outcomes included: cough spirometry; swallowing; forced vital capacity; and scoring on the ALS Functional Rating Scale—Revised.
Results
Treatment was well tolerated with 96% of patients completing the protocol. Significant differences in group change scores were noted for MEP and Dynamic Imaging Grade of Swallowing Toxicity scores (P < 0.02). No differences were noted for other secondary measures.
Discussion
This respiratory training program was well‐tolerated and led to improvements in respiratory and bulbar function in ALS. Muscle Nerve 59:40–46, 2019
See editorial on pages 6–7 in this issue.
Key points
Recent evidence suggests that impaired mitophagy, a process in charge of removing damaged/dysfunctional mitochondria and in part regulated by Parkin, could contribute to the ageing‐related ...loss of muscle mass and function.
In the present study, we show that Parkin overexpression attenuates ageing‐related loss of muscle mass and strength and unexpectedly causes hypertrophy in adult skeletal muscles. We also show that Parkin overexpression leads to increases in mitochondrial content and enzymatic activities. Finally, our results show that Parkin overexpression protects from ageing‐related increases in markers of oxidative stress, fibrosis and apoptosis.
Our findings place Parkin as a potential therapeutic target to attenuate sarcopenia and improve skeletal muscle health and performance.
The ageing‐related loss of muscle mass and strength, a process called sarcopenia, is one of the most deleterious hallmarks of ageing. Solid experimental evidence indicates that mitochondrial dysfunctions accumulate with ageing and are critical in the sarcopenic process. Recent findings suggest that mitophagy, the process in charge of the removal of damaged/dysfunctional mitochondria, is altered in aged muscle. Impaired mitophagy represents an attractive mechanism that could contribute to the accumulation of mitochondrial dysfunctions and sarcopenia. To test this hypothesis, we investigated the impact of Parkin overexpression in skeletal muscles of young and old mice. Parkin was overexpressed for 4 months in muscles of young (3 months) and late middle‐aged (18 months) mice using i.m. injections of adeno‐associated viruses. We show that Parkin overexpression increased muscle mass, fibre size and mitochondrial enzyme activities in both young and old muscles. In old mice, Parkin overexpression increased muscle strength, primordial germ cell‐1α content and mitochondrial density. Parkin overexpression also attenuated the ageing‐related increase in 4‐hydroxynonenal content (a marker of oxidative stress) and type I collagen content (a marker of fibrosis), as well as the number of terminal deoxynucleotidyl transferase dUTP nick‐end labelling‐positive myonuclei (a marker of apoptosis). Overall, our results indicate that Parkin overexpression attenuates sarcopenia and unexpectedly causes hypertrophy in adult muscles. They also show that Parkin overexpression leads to increases in mitochondrial content and enzymatic activities. Finally, our results show that Parkin overexpression protects against oxidative stress, fibrosis and apoptosis. These findings highlight that Parkin may be an attractive therapeutic target with respect to attenuating sarcopenia and improving skeletal muscle health and performance.
Key points
Recent evidence suggests that impaired mitophagy, a process in charge of removing damaged/dysfunctional mitochondria and in part regulated by Parkin, could contribute to the ageing‐related loss of muscle mass and function.
In the present study, we show that Parkin overexpression attenuates ageing‐related loss of muscle mass and strength and unexpectedly causes hypertrophy in adult skeletal muscles. We also show that Parkin overexpression leads to increases in mitochondrial content and enzymatic activities. Finally, our results show that Parkin overexpression protects from ageing‐related increases in markers of oxidative stress, fibrosis and apoptosis.
Our findings place Parkin as a potential therapeutic target to attenuate sarcopenia and improve skeletal muscle health and performance.
Context:
Testosterone's effects on muscle strength and physical function in older men have been inconsistent; its effects on muscle power and fatigability have not been studied.
Objective:
To ...determine the effects of testosterone administration for 3 years in older men on muscle strength, power, fatigability and physical function
Study Design:
In this double-blind, placebo-controlled, randomized trial, healthy men ≥60 years with total testosterone 100–400 ng/dL or free testosterone <50 pg/mL, were randomized to 7.5-g 1% testosterone or placebo gel daily for 3 years.
Outcomes:
Loaded and unloaded stair-climbing power, muscle strength, power, and fatigability in leg press and chest press exercises, and lean mass at baseline, 6, 18, and 36 months.
Results:
The groups were similar at baseline. Testosterone administration for 3 years was associated with significantly greater performance in unloaded and loaded stair-climbing power than placebo (mean (95% CI) estimated between-group difference 10.7W (-4.0,25.5; P=0.026) and 22.4W (4.6,40.3) P=0.027), respectively. Changes in chest press strength (estimated mean difference 16.3N (95% CI 5.5,27.1; P<0.001) and power (mean (95%CI) difference 22.5W (7.5,37.5); P<0.001), and leg press power were significantly greater in men randomized to testosterone than in those randomized to placebo. Lean body mass significantly increased more in the testosterone group.
Conclusion:
Compared to placebo, testosterone replacement in older men for 3 years was associated with modest but significantly greater improvements in stair-climbing power, muscle mass and power. Clinical meaningfulness of these treatment effects and their impact on disability in older adults with functional limitations remains to be studied.
Abstract
Objective
This study aimed to evaluate the intrarater and interrater reliability of isometric quadriceps strength (IQS) using a portable dynamometer in individuals with chronic obstructive ...pulmonary disease (COPD) and to verify their tolerance to the protocol.
Methods
A cross-sectional reliability study was conducted with 50 individuals with stable COPD (34 men and 16 women; mean age = 70 years SD = 8). The main outcome measure was obtained using a portable dynamometer (Microfet 2) to assess IQS. Two masked raters performed 2 assessments in the dominant lower limb on 2 nonconsecutive days. The intraclass correlation coefficient (ICC) was used to verify the intrarater and interrater reliability and was considered excellent when >0.90, with a 5% significance level.
Results
Rater 1 and 2 intrarater reliability was as follows: ICC = 0.96 (95% CI = 0.94 to 0.98) and ICC = 0.97 (95% CI = 0.95 to 0.98), respectively. The interrater reliability was as follows: ICC = 0.96 (95% CI = 0.93 to 0.98). The minimum detectable difference was 4 to 5 peak isometric strength, in mean, for intrarater and interrater reliability. Not all patients presented relevant changes in physiological responses, dyspnea, and lower limb fatigue.
Conclusion
There was an excellent intrarater and interrater reliability for IQS, and the participants tolerated the protocol.
Impact
This tool can be used to assess quadriceps strength in clinical practice in patients with COPD.
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