Oral fucoidan improves muscle size and strength in mice

Abstract

Fucoidan is a sulfated polysaccharide found in a range of brown algae species. Growing evidence supports the long-term supplementation of fucoidan as an ergogenic aid to improve skeletal muscle performance. The aim of this study was to investigate the effect of fucoidan on the skeletal muscle of mice. Male BL/6 mice (N = 8-10) were administered a novel fucoidan blend (FUC, 400 mg/kg/day) or vehicle (CON) for 4 weeks. Treatment and control experimental groups were further separated into exercise (CON+EX, FUC+EX) or no-exercise (CON, FUC) groups, where exercised groups performed 30 min of treadmill training three times per week. At the completion of the 4-week treatment period, there was a significant increase in cross-sectional area (CSA) of muscle fibers in fucoidan-treated extensor digitorum longus (EDL) and soleus fibers, which was accompanied by a significant increase in tibialis anterior (TA) muscle force production in fucoidan-treated groups. There were no significant changes in grip strength or treadmill time to fatigue, nor was there an effect of fucoidan or exercise on mass of TA, EDL, or soleus muscles. In gastrocnemius muscles, there was no change in mRNA expression of mitochondrial biogenesis markers PGC-1α and Nrf-2 in any experimental groups; however, there was a significant effect of fucoidan supplementation on myosin heavy chain (MHC)-2x, but not MHC-2a, mRNA expression. Overall, fucoidan increased muscle size and strength after 4 weeks of supplementation in both exercised and no-exercised mice suggesting an important influence of fucoidan on skeletal muscle physiology.

Keywords: Fucoidan; endurance exercise; muscle contraction; muscle fatigue; skeletal muscle.

FIGURE 1

Effects of exercise and fucoidan on forelimb grip strength and endurance. Comparing pre‐treatment to post‐treatment period, there was no effect of vehicle (VEH) or fucoidan (FUC) treatment on absolute grip strength (a) or grip strength normalized to body mass (b) in either no‐exercise groups. Four weeks of moderate exercise did not significantly affect grip strength (c) or grip strength normalized to body mass (d) in either VEH+EX or FUC+EX groups. Data are expressed as means ± SEM, n = 8 for control, n = 10 for fucoidan, n = 10 for control + exercise, and n = 10 for fucoidan + exercise

FIGURE 2

Effects of exercise and fucoidan on treadmill running endurance. In the VEH and FUC groups that did not exercise, there was no change in time running on the treadmill (a) or distance covered (b) pre‐ or post‐4‐week treatment period. Following 4 weeks of moderate exercise, VEH+EX and FUC+EX had significantly improved both time running (c) and distance traveled (d). Data are expressed as means ± SEM, *p < .05 – main effect for exercise; two‐way ANOVA. n = 8 for control, n = 10 for fucoidan, n = 10 for control + exercise, and n = 10 for fucoidan + exercise

FIGURE 3

Effects of exercise and fucoidan on tibialis anterior (TA) strength. (a) Exercise had no effect on muscle strength normalized to muscle size (sPo); however, both experimental groups receiving fucoidan demonstrated significantly stronger sPo. (b) There was no effect of exercise or fucoidan on force frequency relationship of TA muscle. ^# p < .05 – main effect for fucoidan, two‐way ANOVA. n = 8 for control, n = 10 for fucoidan, n = 10 for control + exercise, and n = 10 for fucoidan + exercise

FIGURE 4

Effects of exercise and fucoidan on mRNA expression in gastrocnemius. Markers of mitochondrial biogenesis (a,b), angiogenesis (c), myogenesis (d), and myosin heavy chain isoform (e,f). *p < .05 – main effect for exercise, ^# p < .05 – main effect for fucoidan; two‐way ANOVA. n = 8 for control, n = 10 for fucoidan, n = 10 for control + exercise, and n = 10 for fucoidan + exercise