Vitamin D and magnesium work together to regulate muscle contraction, energy production, bone strength, and recovery, forming a nutrient pairing that determines how effectively your body responds to training
Research consisting of professional and Olympic sports shows widespread vitamin D and magnesium deficiency, which raises injury risk, slows recovery, weakens strength, and reduces endurance through impaired calcium and adenosine triphosphate (ATP) function
Magnesium deficiency often hides behind normal blood tests, disrupts cellular energy production, worsens fatigue and cramps, and increases soreness, especially in endurance athletes training hard or in hot environments
Endurance exercise increases magnesium needs by shifting the mineral into working muscles and increasing losses through sweat and urine
Supplementing magnesium and vitamin D together improves strength, endurance, recovery, and soreness within weeks, particularly in athletes starting deficient or training at high volumes, without increasing workout intensity