Omega-3 Supplementation Improves Isometric Strength But Not Muscle Anabolic and Catabolic Signaling in Response to Resistance Exercise in Healthy Older Adults

Abstract

Old skeletal muscle exhibits decreased anabolic sensitivity, eventually contributing to muscle wasting. Besides anabolism, also muscle inflammation and catabolism are critical players in regulating the old skeletal muscle’s sensitivity. Omega-3 fatty acids (ω-3) are an interesting candidate to reverse anabolic insensitivity via anabolic actions. Yet, it remains unknown whether ω-3 also attenuates muscle inflammation and catabolism. The present study investigates the effect of ω-3 supplementation on muscle inflammation and metabolism (anabolism/catabolism) upon resistance exercise (RE). Twenty-three older adults (65–84 years; 8♀) were randomized to receive ω-3 (~3 g/d) or corn oil (placebo [PLAC]) and engaged in a 12-week RE program (3×/wk). Before and after intervention, muscle volume, strength, and systemic inflammation were assessed, and muscle biopsies were analyzed for markers of anabolism, catabolism, and inflammation. Isometric knee-extensor strength increased in ω-3 (+12.2%), but not in PLAC (−1.4%; pinteraction = .015), whereas leg press strength improved in both conditions (+27.1%; ptime < .001). RE, but not ω-3, decreased inflammatory (p65NF-κB) and catabolic (FOXO1, LC3b) markers, and improved muscle quality. Yet, muscle volume remained unaffected by RE and ω-3. Accordingly, muscle anabolism (mTORC1) and plasma C-reactive protein remained unchanged by RE and ω-3, whereas serum IL-6 tended to decrease in ω-3 (pinteraction = .07). These results show that, despite no changes in muscle volume, RE-induced gains in isometric strength can be further enhanced by ω-3. However, ω-3 did not improve RE-induced beneficial catabolic or inflammatory adaptations. Irrespective of muscle volume, gains in strength (primary criterion for sarcopenia) might be explained by changes in muscle quality due to muscle inflammatory or catabolic signaling.

Cannabinoid receptor 1 expression is higher in muscle of old vs. young males, and increases upon resistance exercise in older adults

“…Protein extraction and western blot analysis. As previously described 3,22,38 , frozen skeletal muscle tissue (15-20 mg) was homogenized (4 × 20 s) in ice-cold lysis buffer (1/10 w/v; 50 mM Tris-HCl, pH 7.0; 270 mM sucrose; 5 mM EGTA; 1 mM EDTA; 1 mM sodium orthovanadate; 50 mM glycerophosphate; 5 mM sodium pyrophosphate; 50 mM sodium fluoride; 1 mM dithiothreitol; 0.1% Triton X-100; and a complete protease inhibitor tablet) using the FastPrep (MP Biomedicals, Santa Ana, CA). The obtained homogenates were centrifuged at 10,000g (20 min at 4 °C) and the supernatant was stored at − 80 °C.…”

“…Muscle volume and density. As previously reported 3 , a computed tomography scan (Somatom Force ® , Siemens Medical Solutions, Erlangen, Germany) was used to measure the muscle volume of the left upper leg. Four thick axial images of 5 mm were obtained at the midpoint of the distance between the medial edge of the trochanter major and the intercondyloid fossa of the femur.…”

“…Currently, resistance exercise (RE), whether or not combined with protein 2 , omega-3 3 , 4 or vitamin D 5 supplementation, is considered the primary intervention to attenuate age-related muscle deterioration. However, muscular adaptations to RE are less pronounced in old compared to young adults 6 , 7 .…”

Adaptations in Reactive Balance Strategies in Healthy Older Adults After a 3-Week Perturbation Training Program and After a 12-Week Resistance Training Program

“…The perturbation-based training (PBT) group consisted of 16 individuals that followed a perturbation-based balance training program during 3 weeks. The resistance training (RT) group consisted of 14 individuals that were part of a larger group participating in a study that was focused on observing effects of omega-3 supplementation during a 12-week RT training program on muscle strength, and muscle anabolic insensitivity (Dalle et al, 2021 ). Those that indicated their interest, combined the RT training program with the assessment sessions of the present study.…”

“…The 12-week supervised RT program for the lower limbs consisted of three 40-min sessions per week (Dalle et al, 2021 ). Each training session consisted of a 10-min warm-up on a bicycle ergometer at low intensity followed by the RT program.…”