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Healthy aging can be promoted by enhanced metabolic fitness and physical capacity. Mitochondria are chief metabolic organelles with strong implications in aging that also coordinate broad physiological functions, in part, using peptides that are encoded within their independent genome. However, mitochondrial-encoded factors that actively regulate aging are unknown. Here, we report that mitochondrial-encoded MOTS-c can significantly enhance physical performance in young (2 mo.), middle-age (12 mo.), and old (22 mo.) mice. MOTS-c can regulate (i) nuclear genes, including those related to metabolism and proteostasis, (ii) skeletal muscle metabolism, and (iii) myoblast adaptation to metabolic stress. We provide evidence that late-life (23.5 mo.) initiated intermittent MOTS-c treatment (3x/week) can increase physical capacity and healthspan in mice. In humans, exercise induces endogenous MOTS-c expression in skeletal muscle and in circulation. Our data indicate that aging is regulated by genes encoded in both of our co-evolved mitochondrial and nuclear genomes.

High magnitude loading from performing resistance-based exercise has been found to improve tendon strength and reduce symptoms of Achilles tendinopathy (AT) but is difficult to quantify without specialist equipment. Here, we assess the validity and reliability of a novel AT rehabilitation tool (the "PhysViz" system) compared to a "gold-standard" dynamometer for assessing plantarflexion maximal voluntary isometric contractions (MVIC). 41 participants aged 18–60 completed the study. A within-subject test–retest study design was used to examine and compare the validity and reliability of the two systems during plantarflexion MVICs. Test – retest reliability of the two methods were determined by calculating intra-class correlation coefficients (ICCs) and 95% confidence intervals. Method agreement was assessed with Bland – Altman Limits of Agreement (LoA) analysis. The PhysViz demonstrated excellent test–retest reliability; ICC, SEM and MDC were numerically comparable to the dynamometer (ICC 0.93 vs. 0.92; SEM 2.01 vs. 2.95 kg and MDC 5.58 vs. 8.18 kg, respectively), indicating that the novel system is valid and reliable for measuring plantarflexor MVICs. Future studies should address its utility in monitoring AT rehabilitative loading remotely over time. [ABSTRACT FROM AUTHOR]

Background Many individuals develop excess skin (ES) following massive weight loss (MWL). Patient-reported outcomes demonstrate that abdominal ES negatively impacts perceived physical function which is improved by abdominal body contouring surgery (ABCS). However, the effect of ABCS on objective measures of physical function is unknown. Objectives The aim of this study was to examine the impact of ABCS on objective measures of physical function in individuals who have undergone MWL. Methods Patients who have undergone MWL with abdominal ES (grade, ≥2) underwent the following physical function assessments: 9-item modified physical performance test (mPPT), chair stand, star excursion balance test (SEBT), timed up and go (TUG), modified agility T test, and 6-minute walk test (6-MWT). Perception of physical exertion and BODY-Q questionnaire scales were also collected. Nonsurgical controls (n = 21) and those who had undergone ABCS (n = 6) after the first visit performed a second physical function assessment 8 to 12 weeks later to allow for postoperative healing. Results No ceiling or floor effect was detected for any physical function measure. The intraclass correlation coefficient was 0.78 (95% CI, 0.44, 0.91) for the mPPT and >0.80 for all other measures. The effect sizes were 0.74 (75% CI, 0.19, 1.28) for the mPPT, 0.54 (75% CI, 0.00, 1.08) for the SEBT, –0.63 (75% CI, –1.17, –0.09) for the modified agility T test, and 0.79 (75% CI, 0.24, 0.13) for the 6-MWT. Conclusions The mPPT and tests involving dynamic balance, agility, and walking were reliable and showed medium to large effect sizes, suggesting that these tests may be sensitive to change following ABCS. Level of Evidence: 2 [ABSTRACT FROM AUTHOR]

Purpose: Self-myofascial release (SMR) is a common exercise and therapeutic modality shown to induce acute improvements in joint range of motion (ROM) and recovery; however, no long-term studies have been conducted. Static stretching (SS) is the most common method used to increase joint ROM and decrease muscle stiffness. It was hypothesized that SMR paired with SS (SMR+SS) compared with SS alone over a 4-wk intervention would yield greater improvement in knee-extension ROM and hamstring stiffness. Methods: 19 men (22 ± 3 y) with bilateral reduced hamstring ROM had each of their legs randomly assigned to either an SMR+SS oran SS-only group. The intervention consisted of 4 repetitions of SS each for 45 s or the identical amount of SS preceded by 4 repetitions of SMR each for 60 s and was performed on the respective leg twice daily for 4 wk. Passive ROM, hamstring stiffness, rate of torque development (RTD), and maximum voluntary contraction (MVC) were assessed pre-and postintervention. Results: Passive ROM (P < .001 ), RTD, and MVC (P < .05) all increased after the intervention. Hamstring stiffness toward end-ROM was reduced postintervention (P - .02). There were no differences between the intervention groups for any variable. Conclusion. The addition of SMR to SS did not enhance the efficacy of SS alone. SS increases joint ROM through a combination of decreased muscle stiffness and increased stretch tolerance. [ABSTRACT FROM AUTHOR]

Disuse-induced muscle atrophy is accompanied by a blunted postprandial response of the mammalian target of rapamycin complex 1 (mTORC1) pathway. Conflicting observations exist as to whether postabsorptive mTORC1 pathway activation is also blunted by disuse and plays a role in atrophy. It is unknown whether changes in habitual protein intake alter mTORC1 regulatory proteins and how they may contribute to the development of anabolic resistance. The primary objective of this study was to characterize the downstream responsiveness of skeletal muscle mTORC1 activation and its upstream regulatory factors, following 14 days of lower limb disuse in middle-aged men (45-60 yr). The participants were further randomized to receive daily supplementation of 20 g/d of protein (n = 12; milk protein concentrate) or isocaloric carbohydrate placebo (n = 13). Immobilization reduced postabsorptive skeletal muscle phosphorylation of the mTORC1 downstream targets, 4E-BP1, P70S6K, and ribosomal protein S6 (RPS6), with phosphorylation of the latter two decreasing to a greater extent in the placebo, compared with the protein supplementation groups (37% ± 13% vs. 14% ± 11% and 38% ± 20% vs. 25% ± 8%, respectively). Sestrin2 protein was also downregulated following immobilization irrespective of supplement group, despite a corresponding increase in its mRNA content. This decrease in Sestrin2 protein was negatively correlated with the immobilization-induced change in the in silico-predicted regulator miR-23b-3p. No other measured upstream proteins were altered by immobilization or supplementation. Immobilization downregulated postabsorptive mTORC1 pathway activation, and 20 g/day of protein supplementation attenuated the decrease in phosphorylation of targets regulating muscle protein synthesis. [ABSTRACT FROM AUTHOR]