Sex differences in the effect of fish-oil supplementation on the adaptive response to resistance exercise training in older people: a randomized controlled trial.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 27852617 · doi:10.3945/ajcn.116.140780
What was done
Fifty older adults (27 men, mean age 70.6 years; 23 women, mean age 70.7 years) were randomized to receive daily supplementation with either long-chain n-3 polyunsaturated fatty acids (3 g fish oil/day, n = 23) or placebo (3 g safflower oil/day, n = 27) during an 18-week, twice-weekly lower-limb resistance exercise training program. Outcomes evaluated before and after the intervention included muscle anatomic cross-sectional area, muscle fat, isometric and isokinetic torque (at 30, 90, and 240°/s), muscle quality (strength per unit muscle area), physical performance (4-m walk time, chair-rise time), and circulating metabolic and inflammatory markers.
What was found
In women, the fish-oil group had a significantly greater increase in maximal isometric torque (P < 0.05) and muscle quality (P < 0.05) compared to the placebo group; these differences were not observed in men (P > 0.05). Across both sexes, there were no significant between-group differences (P > 0.05) in maximal isokinetic torque, muscle cross-sectional area, muscle fat, 4-m walk time, chair-rise time, glucose, insulin, or inflammatory markers. Plasma triglyceride concentrations decreased significantly more (P < 0.05) in the fish-oil group compared to placebo in both men and women.
Why it matters
The findings indicate that the adjuvant benefits of omega-3 fatty acids for resistance exercise adaptations in older age may be sex-dependent, selectively augmenting muscle quality and isometric strength in older women but not in older men.
Limits
The total sample size was small (50 participants total, divided into four sex-by-treatment subgroups of 11 to 14 participants), which increases the risk of type II errors for modest effects. The study examined only lower-limb resistance training over 18 weeks in healthy older adults, and the abstract does not provide absolute effect estimates or confidence intervals.
Cited by
- supports A study by Stuart Gray's group in Glasgow found that omega-3 supplementation enhanced strength gains from resistance training in older women, but not in older men.