Vitamin D Supplementation Does Not Enhance Gains in Muscle Strength and Lean Body Mass or Influence Cardiorespiratory Fitness in Vitamin D-Insufficient Middle-Aged Men Engaged in Resistance Training

This study examined the impact of vitamin D supplementation on muscle strength, lean body mass (LBM), and cardiorespiratory fitness in vitamin D-insufficient middle-aged men undergoing resistance training. Participants were divided into two groups: one receiving vitamin D supplements and the other a placebo, during a 12-week supervised training program. Results showed increased serum vitamin D levels in the supplement group, but no significant differences between the groups in muscle strength, LBM, fat reduction, or VO₂max. The findings suggest that vitamin D supplementation alone does not enhance physical fitness outcomes in this demographic.

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