Anabolic resistance of muscle protein synthesis to resistance training( Reference Greig, Gray and Rankin 1 ) and nutrition( Reference Guillet, Prod'homme and Balage 2 ) has been proposed as a potential cause of sarcopenia. Fish oil supplementation increases muscle protein synthesis in response to insulin and amino acids in older adults( Reference Smith, Atherton and Reeds 3 ) and may improve adaptations to resistance training in older women. However, this needs to be confirmed by results obtained from placebo controlled trials( Reference Rodacki, Rodacki and Pereira 4 ). The aim of the current study was to determine whether fish oil can enhance adaptations in skeletal muscle function after resistance training in elderly women.
A double-blind randomized placebo-controlled study design was used in this pilot study. Thirteen participants were randomly assigned to receive either 4 g fish oil (containing 1.7 g EPA and 0.4 g DHA) or 4 g control oil (olive oil) daily for 12 weeks. Participants also carried out resistance training twice a week for this period. Plasma profiles (i.e., phospholipid fatty acid composition, glucose, triglycerides, insulin and IL-6), a short performance battery test( Reference Guralnik, Ferrucci and Pieper 5 ), and isometric and isokinetic quadriceps muscle strength were determined pre- and post-intervention. Results are presented as means (SD).
* Denotes a significant difference between groups at post intervention (P<0.05, ANCOVA)
All baseline measures were similar between groups. Plasma EPA and DPA concentrations significantly increased in the fish oil group, compared with the control (P=0.01 and P=0.03 respectively), while insulin resistance, as measured by HOMA-IR, significantly decreased (P=0.03). Post-intervention, the fish oil group showed a greater increase in isometric muscle strength (31.8±8.7 vs. 15±9.6 N/m in fish oil and control groups, respectively; P=0.001) and a gait speed (0.24±0.12 vs. 0.09±0.11 m/s in fish oil and control group, respectively P=0.03) compared with the control group (Table 1). However, post-intervention, there were no differences in isokinetic muscle strength, balance, chair rise time, or plasma IL-6 and triglyceride concentrations.
We have demonstrated that 12 weeks supplementation with 4 g fish oil daily enhance the adaptive responses to resistance exercise and reduce markers of insulin resistance in elderly women, suggesting that fish oil may be beneficial to attenuate age-related loss of muscle mass.