Physiological Responses and Nutritional Intake during a 7-Day Treadmill Running World Record

Ultra-running comprises running events longer than a marathon (>42.2 km). The prolonged duration of ultra-running leads to decrements in most or all physiological parameters and considerable energy expenditure (EE) and energy deficits. SG, 47 years, 162.5 cm, 49 kg, VO_2max 4 mL/kg/min^-1/2.37 L/min^-1, ran continuously for 7 days on a treadmill in 3 h blocks followed by 30 min breaks and slept from 1-5 a.m. Heart rate (HR) oxygen uptake (VO₂), rating of perceived exertion, weight, blood lactate (mmol·L^-1), haemoglobin (g·dL), haematocrit (%) and glucose (mmol·L^-1), and nutrition and hydration were recorded. SG ran for 17.5 h/day, covering ~120 km/day at ~7 km/h. Energy expenditure for each 24 h period was 6878 kcal/day and energy intake (EI) was 2701 kcal/day. EE was 382 kcal/h, with 66.6% from fat and 33.4% from carbohydrate oxidation. 7 day EI was 26,989 kcal and EE was 48,147 kcal, with a total energy deficit (ED) of 21,158 kcal. Average VO₂ was 1.2 L·min^-1/24.7 mL·kg·min^-1, Respriatory echange ratio (RER) 0.80 ± 0.03, HR 120-125 b·min^-1. Weight increased from 48.6 to 49.5 kg. Haemoglobin decreased from 13.7 to 11 g·dL and haematocrit decreased from 40% to 33%. SG ran 833.05 km. SG exhibits an enhanced fat metabolism through which she had a large daily ED. Her success can be attributed to a combination of physiological and psychological factors.