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Mitochondria adapt to increased energy demands during muscle contraction by acutely altering metabolite fluxes and substrate oxidation. With age, an impaired mitochondrial metabolic response may contribute to reduced exercise tolerance and decreased skeletal muscle mass, specific force, increased overall fatty depositions in the skeletal muscle, frailty and depressed energy maintenance. We hypothesized that elevated energy stress in mitochondria with age alters the capacity of mitochondria to utilize different substrates following muscle contraction. To test this hypothesis, we used in vivo electrical stimulation to simulate high‐intensity intervals (HII) or low intensity steady‐state (LISS) exercise in young (5–7 months) and aged (27–29 months) male and female mice to characterize effects of age and sex on mitochondrial substrate utilization in skeletal muscle following contraction. Mitochondrial respiration using glutamate decreased in aged males following HII and glutamate oxidation was inhibited following HII in both the contracted and non‐stimulated muscle of aged female muscle. Analyses of the muscle metabolome of female mice indicated that changes in metabolic pathways induced by HII and LISS contractions in young muscle are absent in aged muscle. To test improved mitochondrial function on substrate utilization following HII, we treated aged females with elamipretide (ELAM), a mitochondrially‐targeted peptide shown to improve mitochondrial bioenergetics and restore redox status in aged muscle. ELAM removed inhibition of glutamate oxidation and showed increased metabolic pathway changes following HII, suggesting rescuing redox status and improving bioenergetic function in mitochondria from aged muscle increases glutamate utilization and enhances the metabolic response to muscle contraction in aged muscle. Key points: Acute local contraction of gastrocnemius can systemically alter mitochondrial respiration in non‐stimulated muscle.Age‐related changes in mitochondrial respiration using glutamate or palmitoyl carnitine following contraction are sex‐dependent.Respiration using glutamate after high‐intensity contraction is inhibited in aged female muscle.Metabolite level and pathway changes following muscle contraction decrease with age in female mice.Treatment with the mitochondrially‐targeted peptide elamipretide can partially rescue metabolite response to muscle contraction. [ABSTRACT FROM AUTHOR]

BackgroundBuilding both strength and endurance has been a challenge in exercise training in the elderly, but dietary supplements hold promise as agents for improving muscle adaptation. Here, we test a formulation of natural products (AX: astaxanthin, 12 mg and tocotrienol, 10 mg and zinc, 6 mg) with both anti-inflammatory and antioxidant properties in combination with exercise. We conducted a randomized, double-blind, placebo-controlled study of elderly subjects (65-82 years) on a daily oral dose with interval walking exercise on an incline treadmill.MethodsForty-two subjects were fed AX or placebo for 4 months and trained 3 months (3×/week for 40-60 min) with increasing intervals of incline walking. Strength was measured as maximal voluntary force (MVC) in ankle dorsiflexion exercise, and tibialis anterior muscle size (cross-sectional area, CSA) was determined from magnetic resonance imaging.ResultsGreater endurance (exercise time in incline walking, >50%) and distance in 6 min walk (>8%) accompanied training in both treatments. Increases in MVC by 14.4% (±6.2%, mean ± SEM, P  0.6 for all).ConclusionsThe AX formulation improved muscle strength and CSA in healthy elderly in addition to the elevation in endurance and walking distance found with exercise training alone. Thus, the AX formulation in combination with a functional training programme uniquely improved muscle strength, endurance, and mobility in the elderly.

High-relief, complex seafloor habitats (e.g., rock and coral reef) present a number of challenges for the deployment of traditional fishing gears, such as seines, gill nets, bottom trawls, and longlines. [...]

Understanding patterns in community structure in large marine ecosystems is necessary for advancing community- and ecosystem-based approaches to marine fisheries management. We analyzed data from a large-scale, fishery-independent video survey to quantify the structure of reef fish communities on offshore hard-bottom reef habitats in the northern Gulf of Mexico (nGOM). A novel aspect of this work is that all species visualized on videos were identified and enumerated over a 13-year period, which allowed for a comprehensive analysis of fish community structure. We observed a total of 243 fish species from 54 families and 14 orders. Species richness and biodiversity varied considerably across the nGOM and were highest in regions that harbor extensive coral reef habitat (south Florida, Louisiana-Texas shelf). Multivariate analyses identified 12 species assemblages, with important fishery species and species of concern (i.e. IUCN-listed) occurring in the largest identified assemblages. One assemblage composed mostly of large-bodied fishery species accounted for 45% by number and 89% by weight of all fish observed. Species assemblages were most strongly associated with depth, temperature, and substrate composition, with weaker associations with the amount of attached algae and vertical relief, while species richness was positively correlated with bottom water temperature. In general, large-scale bathymetric and hydrographic factors (e.g. depth, temperature) were more important than local topographic structure and biogenic habitat in structuring reef fish communities at the spatial scales (i.e.1000 km) considered here. Our results advance ecosystem-based approaches to fisheries management by providing a basis for incorporating multispecies spatial dynamics into the monitoring and assessment of hard-bottom reef fish communities in the nGOM. [ABSTRACT FROM AUTHOR]