A case study evaluation of competitors undertaking an antarctic ultra-endurance event: nutrition, hydration and body composition variables

Abstract

BackgroundThe nutritional demands of ultra-endurance racing are well documented. However, the relationship between nutritional consumption and performance measures are less obvious for athletes competing in Polar conditions. Therefore, the aim of this study was to evaluate dietary intake, hydration status, body composition and performance times throughout an 800-km Antarctic race.MethodsThe event organisers declared that 17 competitors would participate in the South Pole race. Of the 17 competitors, pre-race data were collected from 13 participants (12 males and 1 female (M ± SD): age: 40.1 ± 8.9 years; weight: 83.9 ± 10.3 kg; and body fat percentage: 21.9 ± 3.8%). Dietary recall, body composition and urinary osmolarity were assessed pre-race, midway checkpoint and end race. Data were compared on the basis of fast finishers (the Norwegian team (n = 3) who won in a record of 14 days) and slower finishers (the remaining teams (n = 10) reaching the South Pole between 22 and 28 days).ResultsThe percentage contribution of macronutrients to daily energy intake for all participants was as follows: carbohydrate (CHO) = 23.7% (221 ± 82 g.day−1), fat = 60.6% (251 ± 127 g.day−1) and protein = 15.7% (117 ± 52 g.day−1). Energy demands were closer met by faster finishers compared to slower finishers (5,332 ± 469 vs. 3,048 ± 1,140 kcal.day−1, p = 0.02). Average reduction in body mass throughout the race was 8.3 ± 5.5 kg, with an average loss of lean mass of 2.0 ± 4.1 kg. There was a significant negative correlation between changes in lean mass and protein intake (p = 0.03), and lean mass and energy intake (p = 0.03). End-race urinary osmolarity was significantly elevated for faster finishers compared to slower finishers and control volunteers (faster finishers: 933 ± 157 mOsmol.L−1; slower finishers: 543 ± 92 mOsmol.L−1; control: 515 ± 165 mOsmol.L−1, p = 0.04).ConclusionsThroughout the race, both groups were subjected to a negative change in energy balance which partly explained reduced body mass. Carbohydrate availability was limited inferring a greater reliance on fat and protein metabolism. Consequently, loss in fat-free mass was more prevalent with insufficient protein and caloric intake, which may relate to performance.

Description of Three Female 24-h Ultra-Endurance Race Winners in Various Weather Conditions and Disciplines

“…This is in accordance with previous findings in hot conditions, where a significant negative correlation between performance times and urine osmolality results was observed (11). By contrast, urine osmolality decreased in Case 1 in a cold race, even though faster finishers had higher urine osmolarity in a cold race than slower finishers in Paulin et al (56). The reason might be that the pre-race level of urine osmolality was nearly twice as high as the postrace level in Case 1.…”

Training Intensity Distribution and Changes in Performance and Physiology of a 2nd Place Finisher Team of the Race across America Over a 6 Month Preparation Period

“…It has been reported before, that the cycling speed during the training units was significantly and negatively related to race time (Knechtle et al, 2011, 2012b). Nevertheless, differences in race performances in ultra-endurance events can also result from various other influencing factors like race tactics, weather conditions, motivation (Lahart et al, 2013), sleep deprivation (Knechtle et al, 2012a), nutrition (Stewart and Stewart, 2007; Hulton et al, 2010; Bescós et al, 2012; Lahart et al, 2013; Paulin et al, 2015) and so on, which are not taken into account in this publication.…”

“…The physiological and environmental challenges encountered by the athletes participating in this event are numerous: insufficient energy intake (Knechtle et al, 2005; Hulton et al, 2010), sleep deprivation (Hulton et al, 2010; Lahart et al, 2013) and tough climate conditions like extreme heat in the desert or very high humidity resulting in a decline in performance due to dehydration (Bowen et al, 2006; Paulin et al, 2015). Additionally, over 30,000 m of altitude difference and the corresponding time under hypoxic conditions make the event one of the toughest bike races in the world and the unofficial world championship of ultra-endurance cycling.…”

Nutritional implications for ultra-endurance walking and running events

“…In other activities such as shorter duration endurance events, hydration needs for an event can be approximated during training through methods such as taking body weight before and after training at a duration, intensity, and environment that mimics that of a competition [105]. However, because reductions in body mass can be attributed to substantial breakdown of body tissues such as adipose and muscle [11] and increases in weight can result from reduced diuresis as well as decreases in intracellular osmolytes including glycogen, proteins, and triglycerides, this would be an ineffective strategy for ultra-endurance athletes. The reduced diuresis is induced by activation of vasopressin secretion and the angiotensin–renin–aldosterone mechanism during exercise and the decreases in intracellular osmolytes causes a shift of water to the extracellular compartment during very prolonged exercise [106].…”