Clinical research

This study examined 1,320 women from the Cooper Center Longitudinal Study to evaluate the relationship between serum vitamin D levels, cardiorespiratory fitness, and measures of body composition. Researchers found that higher vitamin D levels were significantly associated with greater cardiorespiratory fitness, measured by maximal treadmill exercise testing, with a positive trend across increasing vitamin D categories. Women classified as fit had higher vitamin D levels than unfit women across multiple measures of body composition, including waist circumference and waist-to-hip ratio. The findings suggest that maintaining adequate vitamin D status may be associated with better aerobic fitness and healthier body composition in women

This study evaluated 59 healthy young women and found that higher blood levels of vitamin D were significantly associated with greater cardiorespiratory fitness, measured by maximal oxygen uptake (VO₂max). Women with higher vitamin D levels also had lower body weight and body fat percentages. These findings suggest that better vitamin D status is associated with greater aerobic fitness and a healthier body composition.

This study analyzed data from nearly 2,000 U.S. adults and found that individuals with higher blood levels of vitamin D had significantly greater cardiorespiratory fitness, measured by VO₂max. Participants in the highest vitamin D group had a 4.3-fold higher cardiorespiratory fitness than those in the lowest group. The association remained significant even after adjusting for age, sex, race, body mass index, smoking, hypertension, and diabetes, with participants in the highest vitamin D group still demonstrating a 2.9-fold greater level of cardiorespiratory fitness than those in the lowest group. Each 10 nmol/L increase in vitamin D was associated with a measurable increase in VO₂max.

A systematic review of clinical trials in athletes found that improving vitamin D status may support physical performance, including aerobic capacity measures such as VO₂ max, particularly in individuals with insufficient vitamin D levels. The authors suggest that vitamin D may influence exercise performance through improved skeletal muscle function, mitochondrial activity, muscle protein synthesis, and oxygen delivery through effects on red blood cell production. Across the studies reviewed, vitamin D supplementation was associated with improvements in aerobic endurance, strength, and power, although results varied based on baseline vitamin D status and training conditions. These findings suggest that maintaining adequate vitamin D levels may support optimal physical performance, especially among individuals with low vitamin D status.

This study evaluated 200 healthy adults and found that individuals with higher blood levels of vitamin D had significantly greater cardiorespiratory fitness, measured by maximal oxygen uptake (VO₂max), even after accounting for age, sex, body mass index, and physical activity. The association was strongest among people with lower levels of physical activity, suggesting that maintaining adequate vitamin D levels may support aerobic fitness, particularly in less active individuals.

This study of elite ballet dancers found that supplementation with 2000 IU of vitamin D daily for 4 months improved strength and jump height and reduced risk of injury. Significant increases were noted for the intervention group for isometric strength (18.7%) and vertical jump (7.1%). The intervention group also sustained significantly less injuries than the controls during the study period.

This review of 11 studies found that vitamin D supplementation for periods of more than 1 week with a minimum dose of 2000 IU/day appears to be an effective strategy for attenuating muscle damage and inflammation after exercise.

This placebo-controlled study that gave athletes and healthy non-athletes 5000 IU of vitamin D per day for 8 weeks found that there was a significant increase in 10 m sprint times and vertical-jump in the vitamin D group whereas the placebo showed no change. This suggests that inadequate vitamin D concentration may be detrimental to musculoskeletal performance in athletes.

This review explores how vitamin D plays an important role in the bidirectional relationship observed between sleep and pain. The authors conclude that supplementation of vitamin D may have a therapeutic role, not only in sleep disorders but also in the prevention and treatment of chronic pain conditions.

This review found that the need for vitamin D in athletes is well established and that vitamin D acts throughout the body to impact a wide variety of health impacts central to peak physical performance including bone and muscle function, immunity, inflammation and respiratory function, protection from injury and disability, and recovery from bone and soft-tissue damage.

This study that gave subjects either 6000 IU vitamin D/day for 8 weeks or a placebo found that vitamin D supplementation significantly improved vitamin D level, max aerobic and anaerobic power, and VO2max in the treatment group compared to the control.