19 International Journal of Sport Nutrition and Exercise Metabolism, 2012, 22, 19 -23 © 2012 Human Kinetics, Inc. The authors are with the Dept. of Human Nutrition, University of Otago, Dunedin, New Zealand. Energy Intakes of Ultraendurance Cyclists During Competition, an Observational Study Katherine E. Black, Paula M.L. Skidmore, and Rachel C. Brown Endurance events >10 hr are becoming increasingly popular but provide numerous physiological challenges, several of which can be attenuated with optimal nutritional intakes. Previous studies in ultraendurance races have reported large energy deficits during events. The authors therefore aimed to assess nutritional intakes in relation to performance among ultraendurance cyclists. This observational study included 18 cyclists in a 384-km cycle race. At race registration each cyclist’s support crew was provided with a food diary for their cyclist. On completion of the race, cyclists were asked to recall their race food and drink intakes. All food and fluids were analyzed using a computer software package. Mean (SD) time to complete the race was 16 hr 21 min (2 hr 2 min). Mean (SD) energy intake was 18.7 (8.6) MJ, compared with an estimated energy require- ment for the race of 25.5 (7.4) MJ. There was a significant negative relationship between energy intake and time taken to complete the race (p = .023, r 2 = –.283). Mean (SD) carbohydrate, fat, and protein intakes were 52 (27), 15.84 (56.43), and 2.94 (7.25) g/hr, respectively. Only carbohydrate (p = .015, r 2 = –.563) and fat intake (p = .037, r 2 = –.494) were associated with time taken to complete the race. This study demonstrates the difficulties in meeting the high energy demands of ultraendurance cycling. The relationship between energy intake and performance suggests that reducing the energy deficit may be advantageous. Given the high carbohydrate intakes of these athletes, increasing energy intake from fat should be investigated as a means of decreasing energy deficits. Keywords: energy balance, fat, cycling Extreme endurance events provide numerous physi- ological challenges, several of which can be attenuated with optimal nutritional intakes. Much of the previous research has been based on running events (Fallon, Broad, Thompson, & Reull, 1998; Glace, Murphy, & McHugh, 2002) or multistage races (Gabel, Aldous, & Edgington, 1995), during which the provision of carbohydrate and fluid has been seen as the major nutritional indicator of performance. Continuous, longer distance events of more than 10 hr duration are becoming increasingly popular, both in the number of events and the popularity of competing in them. One of the likely challenges is an athlete’s ability to consume sufficient energy to cover the large energy requirements to ensure that performance is not compromised. Energy for such races will be derived from a combination of carbohydrate, protein, and fat. Traditionally, because carbohydrate stores in the body are limited, dietary recommendations have primarily focused on obtaining sufficient amounts of carbohydrate. Inadequate ingestion of carbohydrate could have a nega- tive impact on blood glucose concentrations, placing an athlete’s health at risk. Hypoglycemia has been one of the medical complications among athletes competing in grueling endurance events (Peters, 2003). Blood glucose is maintained during ultraendurance events from hepatic glucose output via glycogenolysis and gluconeogenesis, as well as the ingestion of exogenous glucose. During endurance exercise it has been shown that ingesting 40 g of carbohydrate every hour delays fatigue (American Dietetic Association et al., 2009), and this is supported by the observation that a female athlete completing an ultraendurance run consumed around 44 g of carbohy- drate per hour (Moran, Dziedzic, & Cox, 2011). Current recommendations for carbohydrate intake suggest that athletes should ingest 40–75 g/hr during endurance events (Jeukendrup, Jentjens, & Moseley, 2005). This would equal around 640–1,200 kJ/hr and therefore 7,680–14,000 kJ over a 12-hr period. Reported energy expenditure from the limited literature on prolonged continuous endurance exercise has been estimated at 2,780 kJ/hr (Colombani, Mannhart, Wenk, & Frey, 2002). Therefore, based on current guidelines for endurance exercise, energy from exogenous carbohydrate sources would cover only 23–43% of predicted energy requirements. Given that the energy demands of extreme endurance events are so high, obtaining adequate energy per se may limit per- formance. Therefore, reliance on endogenous fuel stores and other exogenous sources such as fat and protein will be important to prevent large energy deficits that could negatively affect performance.