Vitamin D2 (plant-based) and Vitamin D3 apparently have a very important difference when it comes to athletes. Vitamin D2 worsens muscle damage post exercise, vitamin D3 enhances recovery. It is possible that the D2 inhibits or competes for an enzyme that is required to produce D3. The mechanism is not known but what is clear is that taking large doses of D2 does lower D3 levels and this leads to more muscle damage post intense workout.