Study design: Randomized, double-blind, placebo-controlled study with parallel design, in which 40 subjects engage in three exercise sessions. The sessions will be subdivided into a pre-test and test 1 and 2. Between test 1 and 2, participants receive daily for 4 weeks citrus flavonoid supplement or a placebo. Each day, subjects should consume 2 capsules each morning, containing in total 500 mg of citrus flavonoids or 500 mg placebo.