The effect of fish oil supplementation on resistance training-induced adaptations

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

doi:10.1080/15502783.2023.2174704

The effect of fish oil supplementation on resistance training-induced adaptations

J Int Soc Sports Nutr. 2023 Dec;20(1):2174704. doi: 10.1080/15502783.2023.2174704.

Authors

Affiliations

¹ Department of Health, Human Performance, and Recreation, Baylor University, Waco, TX, USA.
² Nutrition Services Division, Walter Reed National Military Medical Center, Bethesda, MD, USA.
³ Kinesiology Department, College of Health Sciences and Human Services, California State University - Monterey Bay, Seaside, CA, USA.
⁴ Department of Educational Psychology, Baylor University, Waco, TX, USA.
⁵ Department of Nutrition, U.S. Military-Baylor University Graduate Program in Nutrition, Fort Sam Houston, TX, USA.
⁶ Department of Human Sciences and Design, Baylor University, Waco, TX, USA.

Abstract

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^-1). 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_SQT) and bench press (1RM_BP) 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 a priori α-level of 0.05 was used to determine statistical significance and Cohen's d was used to quantify effect sizes (ES).

Results: Twenty-one of 28 male and female participants (FOS, n = 10 [4 withdrawals]; PL, n = 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%, p< .001) and did not change in the PL group (+1.3%, p = .938). Similar between-group changes in LBM (FOS: +3.4%, PL: +2.4%, p = .457), FM (FOS: -5.2%, PL: 0.0%, p = .092), and %BF (FOS: -5.9%, PL: -2.5%, p = .136) were observed, although, the between-group ES was considered large for FM (d = 0.84). Absolute and relative (kg·kg [body mass]^-1) 1RM_BP was significantly higher in the FOS group compared to PL (FOS: +17.7% vs. PL: +9.7%, p = .047; FOS: +17.6% vs. PL: +7.3%, p = .011; respectively), whereas absolute 1RM_SQT was similar between conditions (FOS: +28.8% vs. PL: +20.5%, p = .191). Relative 1RM_SQT was higher in the FOS group (FOS: +29.3% vs. PL: +17.9%, p = .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.

Keywords: Hypertrophy; body composition; docosahexaenoic acid; eicosapentaenoic acid; strength.

Publication types

Randomized Controlled Trial

MeSH terms

Body Composition
Dietary Supplements
Docosahexaenoic Acids / pharmacology
Eicosapentaenoic Acid / pharmacology
Female
Fish Oils* / pharmacology
Humans
Male
Muscle Strength
Muscle, Skeletal
Resistance Training* / methods

Substances

Docosahexaenoic Acids
Eicosapentaenoic Acid
Fish Oils

Grants and funding

This study was funded by the Baylor University Research Committee Grant.