Jeffery L Heileson, Steven B Machek, Dillon R Harris, Sara Tomek, Leticia C de Souza, Adam J Kieffer, Nicholas D Barringer, Andrew Gallucci, Jeffrey S Forsse, LesLee K Funderburk
Journal: Journal of the International Society of Sports Nutrition 2023;20(1):2174704
PMID: 36822153
The preservation and promotion of skeletal muscle mass and strength is critical for physical performance and healthy physiology throughout the lifespan. Resistance exercise training (RET) may be one of the best- and well-established strategies to influence these parameters. The study aimed to investigate the impact of fish oil supplement (FOS) compared to placebo (PL) on RET-induced adaptations following a 10-week RET programme. This study was a randomised, single-blind, parallel-group design study. Twenty-eight young male (n = 12) and female (n = 16) adults were recruited and randomly assigned to one of the two groups. Results showed that: - Blood eicosapentaenoic acid + docosahexaenoic acid levels significantly increased in the FOS group (+109.7%) but remained unchanged in the PL group (+1.3%). - lean body mass, fat mass, and percentage body fat changes were similar between groups, although the effect size for fat mass favoured FOS (d = 0.84). - Absolute and relative 1RMBP (1 repetition maximum testing via bench press) strength were significantly higher in the FOS group compared to PL. - Absolute 1RMSQT (1 repetition maximum testing via the back squat) strength was similar between conditions. Authors concluded that FOS may be explored as a feasible and cost-effective nutritional strategy to influence general health and training adaptations, primarily for those with low blood or suboptimal dietary intake of long chain omega-3 polyunsaturated fatty acids.
BACKGROUND
Resistance exercise training (RET) is a common and well-established method to induce hypertrophy and improvement in strength. Interestingly, fish oil supplementation (FOS) may augment RET-induced adaptations. However, few studies have been conducted on young, healthy adults.
METHODS
A randomized, placebo-controlled design was used to determine the effect of FOS, a concentrated source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), compared to placebo (PL) on RET-induced adaptations following a 10-week RET program (3 days·week). Body composition was measured by dual-energy x-ray absorptiometry (LBM, fat mass [FM], percent body fat [%BF]) and strength was measured by 1-repetition maximum barbell back squat (1RM) and bench press (1RM) at PRE (week 0) and POST (10 weeks). Supplement compliance was assessed via self-report and bottle collection every two weeks and via fatty acid dried blood spot collection at PRE and POST. An α-level of 0.05 was used to determine statistical significance and Cohen's was used to quantify effect sizes (ES).
RESULTS
Twenty-one of 28 male and female participants (FOS, = 10 [4 withdrawals]; PL, = 11 [3 withdrawals]) completed the 10-week progressive RET program and PRE/POST measurements. After 10-weeks, blood EPA+DHA substantially increased in the FOS group (+109.7%, < .001) and did not change in the PL group (+1.3%, = .938). Similar between-group changes in LBM (FOS: +3.4%, PL: +2.4%, = .457), FM (FOS: -5.2%, PL: 0.0%, = .092), and %BF (FOS: -5.9%, PL: -2.5%, = .136) were observed, although, the between-group ES was considered large for FM ( = 0.84). Absolute and relative (kg·kg [body mass]) 1RM was significantly higher in the FOS group compared to PL (FOS: +17.7% vs. PL: +9.7%, = .047; FOS: +17.6% vs. PL: +7.3%, = .011; respectively), whereas absolute 1RM was similar between conditions (FOS: +28.8% vs. PL: +20.5%, = .191). Relative 1RM was higher in the FOS group (FOS: +29.3% vs. PL: +17.9%, = .045).
CONCLUSIONS
When combined with RET, FOS improves absolute and relative 1RM upper-body and relative 1RM lower-body strength to a greater extent than that observed in the PL group of young, recreationally trained adults.
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