Energy Balance, Macronutrient Intake, and Hydration Status During a 1,230 km Ultra-Endurance Bike Marathon

Abstract

Athletes competing in ultra-endurance events are advised to meet energy requirements, to supply appropriate amounts of carbohydrates (CHO), and to be adequately hydrated before and during exercise. In practice, these recommendations may not be followed because of satiety, gastrointestinal discomfort, and fatigue. The purpose of the study was to assess energy balance, macronutrient intake and hydration status before and during a 1,230-km bike marathon. A group of 14 well-trained participants (VO2max: 63.2 ± 3.3 ml/kg/min) completed the marathon after 42:47 hr. Ad libitum food and fluid intake were monitored throughout the event. Energy expenditure (EE) was derived from power output and urine and blood markers were collected before the start, after 310, 618, and 921 km, after the finish, and 12 hr after the finish. Energy intake (EI; 19,749 ± 4,502 kcal) was lower than EE (25,303 ± 2,436 kcal) in 12 of 14 athletes. EI and CHO intake (average: 57.1 ± 17.7 g/hr) decreased significantly after km 618 (p < .05). Participants ingested on average 392 ± 85 ml/hr of fluid, but fluid intake decreased after km 618 (p < .05). Hydration appeared suboptimal before the start (urine specific gravity: 1.022 ± 0.010 g/ml) but did not change significantly throughout the event. The results show that participants failed to maintain in energy balance and that CHO and fluid intake dropped below recommended values during the second half of the bike marathon. Individual strategies to overcome satiety and fatigue may be necessary to improve eating and drinking behavior during prolonged ultra-endurance exercise.

Energy Balance During A Self-sufficient, Multistage Ultramarathon

“…This meant the subject experienced a mean energy deficit of 1992 ¡ 952 kcal/day (range: 846-3396 kcal) during the five competitive race days. Previous studies have also demonstrated that athletes were unable to consume enough food/fluid to meet estimated energy requirements during an Ironman triathlon (Kimber, Ross, Mason, & Speedy, 2002) and a 1230 km bike marathon (Geesmann, Mester, & Koehler, 2014). Despite the large negative energy deficit in the present study, the subject reported ''at no time did I feel hungry, I probably took too much food''.…”

Association Between Energy Balance and Metabolic Hormone Suppression During Ultraendurance Exercise

“…We have previously reported dietary intake, energy expenditure, and hydration status from the same data set. 5 We chose this group of athletes because even though the athletes completed the event as a group, their energy intake, and consequently their energy balance varied considerably, 5 whereas environmental factors were identical among all participants.…”

“…Because each athlete consumed food and beverages ad libitum, dietary intake was obtained by direct observation for each individual athlete. 5 Participants received all food and beverages from supporting staff. All food and beverages were packed individually for each athlete and were weighed to the nearest gram prior to loading the support vehicles before the start of the event.…”

“…3,4 Reasons why endurance athletes fail to eat adequately include satiety and gastrointestinal discomfort while exercising, limited gastrointestinal capacity to absorb nutrients, and difficulties in balancing food and fluid consumption to prevent dehydration. 2,5,6 We recently reported that energy balance can vary considerably among ultra-endurance cyclists, even when they competed at similar exercise intensities, and that this large variation in energy balance is predominantly a result of the highly varying intake of solid foods. 5 Previous literature suggests that prolonged endurance exercise is also associated with the suppression of key metabolic hormones, including leptin and testosterone; 7-10 whereas, the effect of prolonged endurance exercise on other metabolic hormones, such as IGF-1 11,12 and ghrelin remain oblique.…”

“…2,5,6 We recently reported that energy balance can vary considerably among ultra-endurance cyclists, even when they competed at similar exercise intensities, and that this large variation in energy balance is predominantly a result of the highly varying intake of solid foods. 5 Previous literature suggests that prolonged endurance exercise is also associated with the suppression of key metabolic hormones, including leptin and testosterone; 7-10 whereas, the effect of prolonged endurance exercise on other metabolic hormones, such as IGF-1 11,12 and ghrelin remain oblique. However, it is only poorly understood whether these endocrine changes are a result of prolonged exercise per se or secondary to the energy deficit that frequently occurs during ultraendurance exercise.…”