Spirulina may have some beneficial effects on exercise performance, but current evidence is mixed and inconclusive.
Preliminary research suggests that spirulina may have a positive effect on endurance training (e.g., running, cycling) by lowering fatigue and increasing power output, possibly through reductions in oxidative stress and increases in hemoglobin levels and oxygen uptake.[1][2][3][4]
In terms of recovery, the majority of research suggests that spirulina has no impact on post-exercise muscle recovery, including delayed onset muscle soreness.[4] However, in athletes with an insufficient intake of dietary antioxidants, spirulina may reduce muscle oxidative damage and accelerate recovery.[3][4]
While the antioxidant effects of spirulina in clinical trials are generally mixed, it’s also important to consider that antioxidant supplementation during or after exercise may blunt the body's natural responses required for muscle adaptation and growth.[5]