The goal of this study is to determine whether Vitamin D supplementation improves strength and bone density, and reduces the risk of injury in collegiate athletes.

Vitamin D is a hormone that is important for bone and muscle health. As such, not having enough vitamin D in your body is associated with increased risk of injury and reduced health and athletic performance. It is often recommended that individuals who have low levels of vitamin D take vitamin D supplements. However, the effects of vitamin D supplementation on health and strength gains in collegiate athletes are not known. The goal of this study is to determine whether vitamin D supplementation increases strength and bone density, while reducing the risk of injury in collegiate athletes. Fasting vitamin D concentrations will be measured and athletes will be supplemented daily with Vitamin D for 8-12 weeks. The amount of supplementation will depend on whether the athlete is categorized as sufficient (>30ng/ml), insufficient (20-35ng/ml), or deficient (<20ng/ml). Vitamin D concentrations, strength, bone density, and injury risk will be assessed before and after the intervention period.

Inclusion Criteria:

• athlete for a sanctioned Virginia Tech sport

Exclusion Criteria:

• pregnant or trying to become pregnant, currently taking vitamin D (>600IU/day), calcium (>1000mg/dl), taking any performance enhancing supplements (example, creatine), or any other medication or nutritional supplements that might influence the study variables, cardiac or thyroid problems, have diabetes, or epilepsy

Any individuals involved in study measures will also be masked.