The effects of resistance exercise and post‐exercise meal timing on the iron status in iron deficient rats

Abstract

Resistance exercise increases heme synthesis in the bone marrow and the hemoglobin (Hb) in iron deficient rats. Post‐exercise early nutrient provision facilitates skeletal muscle protein synthesis compared to late provision. However, the effects of post‐exercise nutrition timing on Hb synthesis are unclear. This study investigated the effect of post‐exercise meal timing on the activity of the key enzyme involved in hemoglobin synthesis, δ‐aminolevulinic acid dehydratase (ALAD), in the bone marrow and examined the Hb concentration in iron deficient rats. Male 4‐week‐old Sprague‐Dawley rats were fed an iron deficient diet containing 12 mg iron/kg and performed climbing exercise (5 min × 6 sets/d, 3 d/w) for 3 weeks. The rats were divided into a group fed a post‐exercise meal early after exercise (E) or a group fed the meal 4h after exercise (L). A single bout of exercise after resistance exercise training for 3 weeks increased the bone marrow ALAD activity, plasma iron concentration and transferrin saturation (TfS). Although the plasma iron concentration and TfS were lower in the E group than in the L group after a single bout of exercise, the basal hematocrit, Hb and total iron binding capacity after 3 weeks did not differ between the groups. Therefore, resistance exercise increases the bone marrow ALAD activity, while the post‐exercise meal timing has no effect on the Hb concentration in iron deficient rats.