Athletic training demands consistent effort in any conditions: rain or shine, morning or night, tired or sore muscles. Vitamin D may help improve the quality, frequency, and duration of workouts, and help facilitate faster muscle recovery.† Klean-D™ 5,000 IU offers natural Vitamin D3 which may be beneficial to athletes who train indoors and receive little natural sunlight. Supplementation with Vitamin D may also help maintain athletes' immunity, musculoskeletal strength, and physical performance.†