Case Study: Providing Nutritional Support to an Ultraendurance Runner in Preparation for a Self-Sufficient Multistage Ultramarathon: Rationed Versus Full Energy Provisions

Publication date: Available online 22 September 2018Source: Wilderness & Environmental MedicineAuthor(s): Rebekah Alcock, Alan McCubbin, Vera Camões-Costa, Ricardo J.S. CostaAbstractTo assess the impact of rationed versus full estimated energy provisions on markers of physiological strain in response to a simulated 250km multistage ultramarathon (MSUM), on two separate occasions, the ultraendurance runner performed a laboratory simulated MSUM, with rationed (RP: 3303±75 kcal⋅day-1) and full (FP: 7156±359 kcal⋅day-1) provisions. Total daily energy expenditure was determined using dual-method indirect calorimetry. Resting metabolic rate, iDXA, and body water were measured at baseline, day 3, and post-MSUM. Blood, urine, and feces were collected, and mood state was measured, d 1 to 5 (before and after running) to determine various physiological strain indices. Heart rate, RPE, thermal comfort, gastrointestinal symptoms, and non-protein oxidation rates were measured every 30min during running. Data were analyzed using single-subject design analysis and interpreted using Cohen's effect size. Energy expenditure was lower on RP (6943±145 kcal⋅day-1) than FP (7486±143 kcal⋅day-1) (Cohen's δ=-3.1). More pronounced exertional strain (RPE δ=1.2, thermal conform δ=0.6, rectal temperature δ=1.0, and plasma cortisol concentration δ=1.7) was observed on RP as the MSUM progressed. Total carbohydrate and fat oxidation during running decreased (0.76 vs. 1.82 g⋅min-1; δ=-3....
Source: Wilderness and Environmental Medicine - Category: Environmental Health Source Type: research