Vitamin D supplementation affects the IGF system in men after acute exercise

Area of Science:

• Endocrinology
• Exercise Physiology
• Nutritional Science

Background:

• Conflicting data exists regarding the Insulin-Like Growth Factor (IGF) system and exercise.
• Vitamin D deficiency is linked to muscle weakness and altered IGF binding proteins, specifically IGFBP3.
• A combined intervention of Vitamin D and acute exercise may modulate the IGF system.

Purpose of the Study:

• To investigate the effects of Vitamin D supplementation combined with different exercise modalities on the IGF system.
• To determine if Vitamin D influences IGF1, IGFBP1, and IGFBP3 levels in men with Vitamin D insufficiency.
• To explore potential mechanisms for improved muscle well-being through Vitamin D and exercise interactions.

Main Methods:

• Men with Vitamin D insufficiency underwent 28 days of Vitamin D3 (4000 IU/d) or placebo supplementation.
• Participants performed 1 hour of stretching (ST), aerobic (AB), or resistance (RT) exercise.
• Serum levels of Total IGF1 (TIGF1), IGFBP1, and IGFBP3 were measured before, immediately after, and 2 hours post-exercise.

Main Results:

• Vitamin D supplementation significantly increased IGFBP3 levels after ST, AB, and RT exercises.
• During RT, the Vitamin D group showed increased IGFBP1 and preserved TIGF1 levels compared to placebo.
• Placebo group experienced a decrease in TIGF1 after resistance exercise, while the Vitamin D group maintained levels.

Conclusions:

• Vitamin D supplementation amplifies IGFBP3, potentially enhancing IGF1 delivery to tissues.
• Combined resistance exercise and Vitamin D supplementation positively modulate the IGF system, increasing IGFBP3 and IGFBP1 while conserving TIGF1.
• These findings suggest a potential benefit for muscle well-being through Vitamin D intervention alongside exercise.