What the research says. A 2026 systematic review and meta-analysis in healthy young to middle-aged adults reported that across nine placebo-controlled eccentric-exercise trials, long-chain omega-3 (EPA/DHA) supplementation reduced delayed-onset muscle soreness and improved muscle strength and range of motion at the point of peak impairment after hard training. The authors described the wider recovery evidence…

What the research says. A meta-analysis of eight randomised trials in 284 athletes found that vitamin D supplementation had no overall effect on muscle strength or on jump power, with a benefit appearing only for lower-limb strength in subgroup analysis. Source. Zhang L, Quan M, Cao ZB. Effect of vitamin D supplementation on upper and…

What the research says. The International Society of Sports Nutrition's position stand on beta-alanine concludes that four weeks of supplementation at 4 to 6 g daily significantly raises muscle carnosine, which acts as an intracellular pH buffer, and that 4 to 6 g daily for at least two to four weeks has been shown to…

What the research says. A 2018 systematic review and meta-analysis in the Journal of the International Society of Sports Nutrition found that caffeine ingestion produced small improvements in maximal upper-body strength and in muscle power, with no significant effect found for lower-body strength. Source. Grgic J, Trexler ET, Lazinica B, Pedisic Z. Effects of caffeine…

What the research says. The International Society of Sports Nutrition's position stand on caffeine reports small-to-moderate performance benefits at doses of roughly 3-6 mg per kilogram of body mass, most consistently for aerobic endurance, while noting that the size of the response varies considerably between individuals and that very high doses mainly add side effects…