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Skeletal Muscle Mitochondrial Adaptations to Maximal Strength Training in Older Adults.

ABSTRACT: Maximal strength training (MST) results in robust improvements in skeletal muscle force production, efficiency, and mass. However, the effects of MST on muscle mitochondria are still unknown. Accordingly, the purpose of this study was to examine, from the molecular level to whole-muscle, mitochondrial adaptations induced by 8 weeks of knee-extension MST in the quadriceps of 10 older adults using immunoblotting, spectrophotometry, high-resolution respirometry in permeabilized muscle fibers, in vivo 31P magnetic resonance spectroscopy (31P-MRS), and gas exchange. As anticipated, MST resulted in an increased isometric knee-extensor force from 133 ± 36 to 147 ± 49 Nm (p < .05) and quadriceps muscle volume from 1,410 ± 103 to 1,555 ± 455 cm3 (p < .05). Mitochondrial complex (I-V) protein abundance and citrate synthase activity were not significantly altered by MST. Assessed ex vivo, maximal ADP-stimulated respiration (state 3CI+CII, PRE: 23 ± 6 and POST: 14 ± 5 ρM·mg-1·s-1, p < .05), was decreased by MST, predominantly, as a result of a decline in complex I-linked respiration (p < .05). Additionally, state 3 free-fatty acid linked respiration was decreased following MST (PRE: 19 ± 5 and POST: 14 ± 3 ρM·mg-1·s-1, p < .05). Assessed in vivo, MST slowed the PCr recovery time constant (PRE: 49 ± 13 and POST: 57 ± 16 seconds, p < .05) and lowered, by ~20% (p = .055), the quadriceps peak rate of oxidative ATP synthesis, but did not significantly alter the oxidation of lipid. Although these, likely qualitative, mitochondrial adaptations are potentially negative in terms of skeletal muscle energetic capacity, they need to be considered in light of the many improvements in muscle function that MST affords older adults.

SUBMITTER: Berg OK

PROVIDER: S-EPMC7896183 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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Skeletal Muscle Mitochondrial Adaptations to Maximal Strength Training in Older Adults.

Berg Ole Kristian OK Kwon Oh Sung OS Hureau Thomas J TJ Clifton Heather L HL Thurston Taylor S TS Le Fur Yann Y Jeong Eun-Kee EK Trinity Joel D JD Richardson Russell S RS Wang Eivind E Layec Gwenael G

The journals of gerontology. Series A, Biological sciences and medical sciences 20201101 12

Maximal strength training (MST) results in robust improvements in skeletal muscle force production, efficiency, and mass. However, the effects of MST on muscle mitochondria are still unknown. Accordingly, the purpose of this study was to examine, from the molecular level to whole-muscle, mitochondrial adaptations induced by 8 weeks of knee-extension MST in the quadriceps of 10 older adults using immunoblotting, spectrophotometry, high-resolution respirometry in permeabilized muscle fibers, in vi ...[more]

PMID: 32253421

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Project description:Several studies suggest resistance training (RT) while supplementing with various protein supplements can enhance strength and muscle mass in older individuals. However, to date, no study has examined the effects of RT with a peanut protein powder (PP) supplement on these outcomes. Herein, 39 older, untrained individuals (n = 17 female, n = 22 male; age = 58.6 ± 8.0 years; body mass index =28.7 ± 5.8) completed a 6-week (n = 22) or 10-week (n = 17) RT program, where full-body training was implemented twice weekly (ClinicalTrials.gov trial registration NCT04015479; registered July 11, 2019). Participants in each program were randomly assigned to consume either a PP supplement once per day (75 total g powder providing 30 g protein, > 9.2 g essential amino acids, ~ 315 kcal; n = 20) or no supplement (CTL; n = 19). Right leg vastus lateralis (VL) muscle biopsies were obtained prior to and 24 h following the first training bout in all participants to assess the change in myofibrillar protein synthetic rates (MyoPS) as measured via the deuterium-oxide (D2O) tracer method. Pre- and Post-intervention testing in all participants was conducted using dual energy x-ray absorptiometry (DXA), VL ultrasound imaging, a peripheral quantitative computed tomography (pQCT) scan at the mid-thigh, and right leg isokinetic dynamometer assessments. Integrated MyoPS rates over a 24-h period were not significantly different (p < 0.05) between supplement groups following the first training bout. Regarding chronic changes, there were no significant supplement-by-time interactions in DXA-derived fat mass, lean soft tissue mass or percent body fat between supplementation groups. There was, however, a significant increase in VL thickness in PP versus CTL participants when the 6- and 10-week cohorts were pooled (interaction p = 0.041). There was also a significant increase in knee flexion torque in the 10-week PP group versus the CTL group (interaction p = 0.032). In conclusion, a higher-protein, defatted peanut powder supplement in combination with RT positively affects select markers of muscle hypertrophy and strength in an untrained, older adult population. Moreover, subanalyses indicated that gender did not play a role in these adaptations.

Dataset Information

Skeletal Muscle Mitochondrial Adaptations to Maximal Strength Training in Older Adults.

Publications

Skeletal Muscle Mitochondrial Adaptations to Maximal Strength Training in Older Adults.

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