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Objectives: To investigate the synergist effects of exercise and β-hydroxy β-methylbutyrate (HMB) supplementation on disability, cognitive and physical function, and muscle power in institutionalized older people. Design: Cluster-randomized controlled trial. Participants: Seventy-two institutionalized older adults (age = 83 ± 10 years old; 63% women) were randomized in four groups: exercise plus placebo (EX), HMB supplementation, EX plus HMB supplementation (EX + HMB), and control (CT). Intervention: The exercising participants completed a 12-week tailored multicomponent exercise intervention (Vivifrail; 5 days/week of an individualized resistance, cardiovascular, balance and flexibility program), whereas the HMB groups received a drink containing 3 g/day of HMB. Measurements: Participants were assessed Pre and Post intervention for disability and cognitive function (validated questionnaires), physical function (short physical performance battery, SPPB), handgrip strength and sit-to-stand relative muscle power. Linear mixed-effect models were used to compare changes among groups. Results: Compared to baseline, both EX and EX + HMB improved cognitive function (+2.9 and +1.9 points; p 0.05). Significant between-group differences were noted between CT, EX and EX + HMB for cognitive function (p

Abstract Background Maximum muscle power (Pmax) is a biomarker of physical performance in all ages. No longitudinal studies have assessed the effects of aging on Pmax obtained from the torque‐velocity (T‐V) relationship, which should be considered the ‘gold standard’. This study evaluated the longitudinal changes in the T‐V relationship and Pmax of the knee‐extensor muscles in young, middle‐aged, and older adults after 10 years of follow‐up. Methods Four hundred eighty‐nine subjects (311 men and 178 women; aged 19–68 years) were tested at baseline and after a 10‐year follow‐up. Anthropometric data, daily protein intake, physical activity level (PAL), and knee‐extension muscle function (isometric, isokinetic, and isotonic) were evaluated. A novel hybrid equation combining a linear and a hyperbolic (Hill‐type) region was used to obtain the T‐V relationship and Pmax of the participants, who were grouped by sex and age (young: 20–40 years; middle‐aged: 40–60 years; and old: ≥60 years). Linear mixed‐effect models were used to assess effects of time, sex, and age on T‐V parameters, Pmax, and body mass index (BMI). Additional analyses were performed to adjust for changes in daily protein intake and PAL. Results Pmax decreased in young men (−0.6% per year; P

Estimating lower-limb muscle power during sit-to-stand (STS) tests is feasible for large-scale implementation. This study investigated 1) whether age, functional limitations and sex have an influence on the movement strategy and power production during STS; and 2) potential differences between STS power estimated with either a simple equation or a sensor. Five-repetition STS data of 649 subjects (♂352 ♀297) aged 19 to 93 years were included. Subjects were divided in different age groups and levels of functioning. A body-fixed sensor measured (sub)durations, trunk movement (flexion/extension) and STS muscle power (Psensor). Additionally, mean STS muscle power was calculated by a mathematic equation (Alcazar et al., 2018b)Pformula.Results revealed that 1) older subjects and women showed greater trunk flexion before standing up than younger subjects and men, respectively (both p

Abstract Background Although growth differentiation factor 15 (GDF15) is known to increase with disease and is associated with low physical performance, the role of GDF15 in normal ageing is still not fully understood. Specifically, the influence of circulating GDF15 on impairments in maximal muscle power (a major contributor to functional limitations) and the underlying components has not been investigated. Methods Data from 1305 healthy women and men aged 20 to 93 years from The Copenhagen Sarcopenia Study were analysed. Circulating levels of GDF15 and markers of inflammation (tumor necrosis factor‐alpha, interleukin‐6, and high‐sensitivity C‐reactive protein) were measured by ELISA (R&D Systems) and multiplex bead‐based immunoassays (Bio‐Rad). Relative (normalized to body mass), allometric (normalized to height squared), and specific (normalized to leg muscle mass) muscle power were assessed by the Nottingham power rig [leg extension power (LEP)] and the 30 s sit‐to‐stand (STS) muscle power test. Total body fat, visceral fat, and leg lean mass were assessed by dual energy X‐ray absorptiometry. Leg skeletal muscle index was measured as leg lean mass normalized to body height squared. Results Systemic levels of GDF15 increased progressively as a function of age in women (1.1 ± 0.4 pg·mL−1·year−1) and men (3.3 ± 0.6 pg·mL−1·year−1) (both P

Abstract Background Chronic low‐grade inflammation has been suggested as one of the key elements in the development of sarcopenia, but in contrast to disease‐related loss of muscle mass, the role of chronic low‐grade inflammation in age‐related (primary) sarcopenia is still not clear. The aim of this study was to investigate low‐grade inflammation in relation to age and the potential association between inflammatory biomarkers and body composition, muscle strength and physical performance in a healthy Danish cohort. Methods There were 1160 generally healthy men and women (range: 22–93 years) included. Appendicular lean mass (ALM) and visceral fat normalized to height (kg/m2) was assessed by dual‐energy X‐ray absorptiometry (iDXA, GE Lunar). Muscle strength and physical performance were evaluated by handgrip strength (HGS), 30 s sit‐to‐stand performance, and maximal gait speed (GS). Systemic levels of TNF‐α, IL‐6, IL‐1β, IL‐4, IL‐13, and IFN‐γ were measured using multiplex bead‐based immunoassays (Bio‐Rad). hsCRP was assessed using latex particle‐enhanced immunoturbidimetric assays (Roche Diagnostics). Results With age, ALM/h2, HGS, sit‐to‐stand performance and GS decreased, whereas visceral fat/h2 increased in both men and women (P

Abstract The purposes of this study were: (i) to evaluate the association of sit-to-stand (STS) power and body composition parameters [body mass index (BMI) and legs skeletal muscle index (SMI)] with age; (ii) to provide cut-off points for low relative STS power (STSrel), (iii) to provide normative data for well-functioning older adults and (iv) to assess the association of low STSrel with negative outcomes. Cross-sectional design (1369 older adults). STS power parameters assessed by validated equations, BMI and Legs SMI assessed by dual-energy X-ray absorptiometry were recorded. Sex- and age-adjusted segmented and logistic regression analyses and receiver operator characteristic curves were used. Among men, STSrel showed a negative association with age up to the age of 85 years (− 1.2 to − 1.4%year−1; p

Abstract Background A validated, standardized, and feasible test to assess muscle power in older adults has recently been reported: the sit‐to‐stand (STS) muscle power test. This investigation aimed to assess the relationship between relative STS power and age and to provide normative data, cut‐off points, and minimal clinically important differences (MCID) for STS power measures in older women and men. Methods A total of 9320 older adults (6161 women and 3159 men) aged 60–103 years and 586 young and middle‐aged adults (318 women and 268 men) aged 20–60 years were included in this cross‐sectional study. Relative (normalized to body mass), allometric (normalized to height squared), and specific (normalized to legs muscle mass) muscle power values were assessed by the 30 s STS power test. Body composition was evaluated by dual energy X‐ray absorptiometry and bioelectrical impedance analysis, and legs skeletal muscle index (SMI; normalized to height squared) was calculated. Habitual and maximal gait speed, timed up‐and‐go test, and 6 min walking distance were collected as physical performance measures, and participants were classified into two groups: well‐functioning and mobility‐limited older adults. Results Relative STS power was found to decrease between 30–50 years (−0.05 W·kg−1·year−1; P > 0.05), 50–80 years (−0.10 to −0.13 W·kg−1·year−1; P

Abstract Background Despite no international consensus on the diagnostic criteria for sarcopenia, low lean mass, muscle strength, and physical function are important risk factors for disability, frailty, and mortality in older individuals, as well as in a wide range of patients with muscle loss. Here, we provide a population‐based reference material of total and regional lean body mass, muscle strength/power parameters, and physical function in a healthy cohort of Danish men and women across the lifespan. Methods Volunteers aged 20–93 years from the Copenhagen City Heart Study were invited to establish a Danish reference material (Copenhagen Sarcopenia Study) on lean mass characteristics [appendicular lean mass (ALM), iDXA, GE Lunar], muscle function [handgrip strength (HGS), Jamar dynamometer and leg extension power (LEP), Nottingham Power Rig], and physical function [30 s sit‐to‐stand test (STS), 10‐m maximal and habitual gait speed (GS)]. Results A total of 1305 participants [729 women (age: 56.4 ± 18.9 years, height: 1.66 ± 0.01 m, body mass index: 24.6 ± 4.3 kg/m2 and 576 men, age: 57.0 ± 17.5 years, height: 1.80 ± 0.07 m, body mass index: 26.0 ± 3.9 kg/m2] completed all measurements and were included in the present analysis. Lean mass characteristics (TLM, ALM, and ALM/h2) decreased with increasing age in both men and women (P < 0.001). Men demonstrated larger absolute and relative total ALM and higher HGS and LEP compared with women at all age intervals (P < 0.001). HGS and LEP decreased progressively with age in both men and women (P < 0.01); 30 s STS performance, habitual GS, and maximal GS decreased at an accellerated rate of decline with increasing age in both men and women (P < 0.001). Habitual GS was reduced in men and women aged ≥70 years, while maximal GS was reduced from the age of ≥60 years compared with young adults (P < 0.001). Regardless of sex, 30 s STS was reduced from the age of ≥50 years compared with the young reference group (P < 0.001) Conclusions While the power‐based measurements (LEP and 30 s STS) started to decline already at age +50 years, less power‐based parameters (GS and HGS) and lean mass characteristics (TLM, ALM, and ALM/h2) remained unaltered until after the age of +70 years. Notably, the cut‐off thresholds derived in the present study differed from earlier reference data, which underlines the importance of obtaining updated and local reference materials.

BackgroundPower-oriented resistance training (PRT) is one of the most effective exercise programs to counteract neuromuscular and physical function age-related declines. However, the optimal load that maximizes these outcomes or the load-specific adaptations induced on muscle power determinants remain to be better understood. Furthermore, to investigate whether these adaptations are potentially transferred to an untrained limb (i.e., cross-education phenomenon) could be especially relevant during limb-immobilization frequently observed in older people (e.g., after hip fracture).MethodsAt least 30 well-functioning older participants (>65 years) will participate in a within-person randomized controlled trial. After an 8-week control period, the effects of two 12-week PRT programs using light vs. heavy loads will be compared using an unilateral exercise model through three study arms (light-load PRT vs. non-exercise; heavy-load PRT vs. non-exercise; and light- vs. heavy- load PRT). Muscle-tendon function, muscle excitation and morphology and physical function will be evaluated to analyze the load-specific effects of PRT in older people. Additionally, the effects of PRT will be examined on a non-exercised contralateral limb.DiscussionTailored exercise programs are largely demanded given their potentially greater efficiency preventing age-related negative consequences, especially during limb-immobilization. This trial will provide evidence supporting the use of light- or heavy-load PRT on older adults depending on individual needs, improving decision making and exercise program efficacy.Clinical Trial RegistrationNCT03724461 registration data: October 30, 2018.

The shape of the force-velocity (F-V) relationship has important implications for different aspects of muscle physiology, such as muscle efficiency and fatigue, the understanding of the pathophysiology of several myopathies or the mechanisms of muscle contraction per se, and may be of relevance for other fields, such as the development of robotics and prosthetic applications featuring natural muscle-like properties. However, different opinions regarding the shape of the F-V relationship and the underlying mechanisms exist in the literature. In this review, we summarize relevant evidence on the shape of the F-V relationship obtained over the last century. Studies performed at multiple scales ranging from the sarcomere to the organism level have described the concentric F-V relationship as linear, hyperbolic or double-hyperbolic. While the F-V relationship has most frequently been described as a rectangular hyperbola, a large number of studies have found deviations from the hyperbolic function at both ends of the F-V relation. Indeed, current evidence suggests that the F-V relation in skeletal muscles follows a double-hyperbolic pattern, with a breakpoint located at very high forces/low velocities, which may be a direct consequence of the kinetic properties of myofilament cross-bridge formation. Deviations at low forces/high velocities, by contrast, may be related to a recently discovered, calcium-independent regulatory mechanism of muscle contraction, which may also explain the low metabolic cost of very fast muscle shortening contractions. Controversial results have also been reported regarding the eccentric F-V relationship, with studies in prepared muscle specimens suggesting that maximum eccentric force is substantially greater than isometric force, whereas in vivo studies in humans show only a modest increase, no change, or even a decrease in force in lengthening contractions. This review discusses possible reasons reported in the literature for these discrepant findings, including the testing procedures (familiarization, pre-load condition, and temperature) and a potential neural inhibition at higher lengthening velocities. Finally, some unresolved questions and recommendations for F-V testing in humans are reported at the end of this document.

This study aimed to evaluate the effect of the stretch-shortening cycle (SSC) on different portions of the force–velocity (F–V) relationship in older adults with and without chronic obstructive pulmonary disease (COPD), and to assess its association with physical function. The participants were 26 older adults with COPD (79 ± 7 years old; FEV1 = 53 ± 36% of predicted) and 10 physically active non-COPD (77 ± 4 years old) older adults. The F–V relationship was evaluated in the leg press exercise during a purely concentric muscle action and compared with that following an eccentric muscle action at 10% intervals of maximal unloaded shortening velocity (V0). Vastus lateralis (VL) muscle thickness, pennation angle (PA), and fascicle length (FL) were assessed by ultrasound. Habitual gait speed was measured over a 4-m distance. COPD subjects exhibited lower physical function and concentric maximal muscle power (Pmax) values compared with the non-COPD group (both p < 0.05). The SSC increased force and power values among COPD participants at 0–100 and 1–100% of V0, respectively, while the same was observed among non-COPD participants only at 40–90 and 30–90% of V0, respectively (all p < 0.05). The SSC induced greater improvements in force, but not power, among COPD compared with non-COPD subjects between 50 and 70% of V0 (all p < 0.05). Thus, between-group differences in muscle power were not statistically significant after the inclusion of the SSC (p > 0.05). The SSC-induced potentiation at 50–100% of V0 was negatively associated with physical function (r = -0.40–0.50), while that observed at 80–100% of V0 was negatively associated with VL muscle thickness and PA (r = -0.43–0.52) (all p < 0.05). In conclusion, older adults with COPD showed a higher SSC-induced potentiation compared with non-COPD subjects, which eliminated between-group differences in muscle power when performing SSC muscle actions. The SSC-induced potentiation was associated with lower physical function, VL muscle thickness, and VL PA values. The SSC-induced potentiation may help as a compensatory mechanism in those older subjects with a decreased ability to produce force/power during purely concentric muscle actions.

Chronic obstructive pulmonary disease (COPD) is characterized by persistent respiratory symptoms and airflow limitation. Apart from the ventilatory limitations, patients with COPD present an impaired exercise capacity that limits their ability to perform the activities of daily living and impact negatively on their quality of life. Limb muscle dysfunction is a systemic consequence of COPD associated with exercise intolerance, poor quality of life and increased mortality. This COPD-related syndrome is characterized by reduced muscle cross-sectional area, strength and endurance, and is highly prevalent among COPD patients. Thus, pulmonary rehabilitation (PR) is recommended in order to combat the negative consequences of COPD on patients’ exercise capacity and quality of life. Exercise training is regarded as the cornerstone of PR and can be implemented at any stage of the disease. To date, the combination of resistance and endurance training (i.e. concurrent training) has demonstrated to be the most beneficial exercise intervention in COPD. Concurrent training provides clinically and statistically significant benefits in exercise tolerance and quality of life to patients with COPD. In addition, there are other potential adjuncts to exercise training and strategies to enhance the implementation of PR programs in COPD patients.