Vitamin D supplementation effects on the IGF system in men after acute exercise (828.15)

Abstract

Conflicting data between the IGF system and exercise may be due to IGF binding proteins. Vit D insufficiency is related to muscle weakness and IGFBP3. To determine if a combination of Vit D and acute exercise can alter the IGF system, Vit D insufficient and deficient men (39.0±8.6yo with 25OH D 20.0±7.7ng/mL) did one hour of stretching (ST), aerobic (AB), and resistive (RT) exercises, before and after 28 d of 4000IU/d Vit D3 (D, n=6) or Placebo (P, n=7). ST, an attention/time control visit, alternated passive movements. AB was moderate intensity treadmill walking. RT rotated moderate strength 50% 1‐RM repetitions (15, 10) of squat, bench press, leg press, and lat pull down. Serum total IGF1 (TIGF1), IGFBP1 (BP1), IGFBP3 (BP3) were measured before (T1, fasting), immediately after (T2), and 2 h post (T3) exercise. After ST, BP3 was higher in the D group at T2 (2948, 2130 ng/mL; p<0.03) and T3 (3087, 2212; p<0.02). During RT, TIGF1 decreased in the P group from T1 to T3 (151.4, 107.3 ng/mL; p<0.05), while BP1 increased in the D group from T1 to T3 (26.5, 96.2 ng/mL; p<0.05). RT BP3 was higher at T1, T2, and T3 in the D group (2932.5, 2110.7; p<0.03), (3163.9, 2392.5; p<0.04), and (3355.3, 2353.1; p<0.01). In AB, BP3 was higher in the D group at T2 (3128.6, 2226.3.0; p<0.04) and T3 (2949.7, 2135.1; p<0.05). D supplementation increased BP3 after low or moderate activity which may increase the delivery of IGF1 to tissues. Resistance exercise with Vit D not only heightened BP3 and BP1 levels but also maintained TIGF1 levels, potentially altering the IGF system for enhanced muscle health.