Inflammation And Hepcidin Responses To Nutritional Supplementation During Load Carriage And Short-term Military Training: 629 Board #1 June 1, 1

Prolonged low-to-moderate intensity load carriage (LC) endurance-type exercise may exacerbate the inflammatory and hepcidin response to traditional endurance exercise modes and contribute to poor iron status, particularly when LC is performed repeatedly during military training operations that result in severe energy deficits. Nutritional supplementation may mitigate this response by attenuating the energy deficit. PURPOSE: Two studies were conducted to assess inflammation and hepcidin responses to acute LC exercise and short-term (4-d) military training, with or without nutritional supplementation. METHODS: Study 1: 40 adults fed eucaloric diets were randomly assigned to perform 90-min, intensity-matched (2.2 ± 0.1 VO2 L·m-1) LC (treadmill, 24 kg carried) or cycle ergometry (CE) exercise, during which protein and carbohydrate (10 g protein/46 g carbohydrate) or control (non-nutritive) drinks were consumed. Study 2: 73 soldiers were randomly assigned to receive three combat rations alone, three rations and four 20 g protein-based snacks, or three rations and four 48 g carbohydrate-based snacks during a 4-d arctic military training operation (51 kM ski march, 45 kg LC) that produced a 55%, energy deficit. Interleukin-6 (IL-6), hepcidin, and ferritin were determined at baseline, 3-h, 24-h, 48-h, and 72-h post-exercise for study 1 and before (PRE) and after (POST) the 4-d training in study 2. RESULTS: Study 1: IL-6 was higher 3-h and 24-h for CE only (mode x time, P < 0.05), but hepcidin peaked 3-h and recovered by 48-h, and ferritin peaked 24-h and remained elevated 72-h (P < 0.05), regardless of exercise mode and nutrition supplementation. Study 2: IL-6, hepcidin and ferritin were higher (P < 0.05) POST compared to PRE, regardless of diet group. Energy expenditure (r = 0.40), intake (r = -0.26) and balance (r = -0.43) were associated (P < 0.05) with POST hepcidin levels. CONCLUSION: Inflammation and hepcidin increase in response to acute LC and traditional, non-weight-bearing endurance exercise and are not affected by supplemental nutrition when performed during energy balance. However, increasing energy intake, regardless of macronutrient source, during short-term military training consisting of repeat LC bouts may attenuate hepcidin and potential decrements in iron status by minimizing the energy deficit.