<p dir="ltr">Fucoidan extracted from brown algae has been shown to improve aerobic capacity and increase muscle size and strength in mice. Whether these beneficial effects translate to humans is unknown. This study investigated the effect of a resistance training program in combination with fucoidan supplementation on measures of strength and performance in apparently healthy adults. In a double-blind placebo control fashion, 20 participants (9 male and 11 female) were randomised to supplement with fucoidan ( N = 10, 1 g/day) or placebo ( N = 10, 1 g/day) during six weeks of resistance training. Body composition, muscle strength, anaerobic performance, and blood measurements were compared pre- and post-resistance training. Strength measured by 1 repetition max back squat was significantly increased in both placebo and fucoidan supplemented groups ( p < 0.001), with no significant effect of treatment observed ( p = 0.48). Peak power and relative peak power produced during a Wingate test were significantly increased in the fucoidan supplemented group only ( p < 0.05). There was a significant treatment effect on body composition ( p < 0.05), with the fucoidan supplemented group demonstrating a significant increase in lean body mass and a decrease in body fat % ( p < 0.05). In conclusion, fucoidan supplementation during resistance training may provide a viable strategy for enhancing muscle anaerobic performance as well as improving metabolism and body composition.</p>