Negative Energy Balance Does Not Alter Fat-Free Mass During the Yukon Arctic Ultra—The Longest and the Coldest Ultramarathon

Abstract

Purpose: The objective of this study was to determine alterations in caloric balance, body composition, metabolites, and cytokines in athletes participating in the Yukon Arctic Ultra.Methods: Ten participants traveling on foot in the 2017 692-km event were recruited for the study. Measurements and samples were obtained at pre-event, 278 km (C1), 384 km (C2), and post-event. Body composition measurements were obtained using bioelectrical impedance analysis. Accelerometer devices were utilized to provide an estimation of caloric expenditure and dietary recalls provided assessments of caloric intake. Blood serum samples were collected, processed, and analyzed using enzyme-linked immunosorbent assays or nuclear magnetic resonance. Results were analyzed using linear mixed model, presented as means ± SD, and considered significant at p < 0.05.Results: Participants (8 males, 2 females; age: 37 ± 10 years; body mass index: 24.4 ± 2.5 kg/m2) were recruited. Four males and one female completed the entire event in 260 ± 19 h. Caloric intake/expenditure was 4,126 ± 1,115 kcal/day and 6,387 ± 781 kcal/day, respectively, indicating a caloric deficit of 2,261 ± 1,543 kcal/day. Total mass, body mass index, and fat mass were reduced at each time point of the event. Fat-free mass (FFM) was unchanged throughout the event. Follistatin was increased at C1 (1,715 ± 876 pg/ml) in comparison to baseline. Acetoacetate increased significantly at post-event (6.1 ± 1.5 mg/ml).Conclusions: Despite a pronounced caloric deficit and sustained activity under extreme cold conditions, FFM was preserved with an increase in serum follistatin and acetoacetate. Future studies should be directed at the role of nutrient strategies and/or training methods on the retention of FFM under these conditions.

Body Composition Changes During a 24-h Winter Mountain Running Race Under Extremely Cold Conditions

“…An interesting fact was the finding that runners with a higher decrease in percentage BF showed a higher increase in SM. Investigations in athletes exercising in extremely cold conditions for extended periods (Coker et al, 2017; Johannsen et al, 2018; Schalt et al, 2018; Shepard, 1985, 1993) found significant reductions in BF, but no change in fat free mass, despite sustained negative energy balance, similarly as in the present study. Moderate negative associations between fat-free mass and percentage BF have been reported by Baur et al (2016).…”

“…Total body water and SM remained stable in both sexes. No changes in fat free mass and TBW were noted during The Yukon Arctic Ultra in the study by Schalt et al (2018). A study during an ultra-distance race in cold weather in Alaska (17 male and 3 female athletes) with temperatures ranging from -14 to -2°C (Stuempfle et al, 2003) described a mean BM loss of 1.2 kg; similarly as in the present male runners.…”

“…A case study of competitors undertaking an antarctic ultra-endurance event showed a reduction in both BM and lean mass (Paulin et al, 2015). On the contrary, recent studies in the cold antarctic environment (Coker et al, 2017; Johannsen et al, 2018; Schalt et al, 2018) demonstrated preserved fat free mass in the athletes.…”

“…Coker et al (2017) reported almost complete muscle preservation under extreme conditions of prolonged cold exposure during the Yukon Arctic Ultra in athletes at all distances, also at the shortest distance with twice less kilometers than the distance covered on average by the present runners during 24 h. Higher BF and BM loss could then be masked by the synthesis of a similar mass of lean tissue in some of the present 24-h runners, both males and females. Results suggest that runners may utilize a combination of training, pacing strategies and nutrition that enable adaptive responses to the environmental stress (Schalt et al, 2018). Future studies should be directed at measuring dietary intake with the molecular components of protein metabolism and/or training methods that may be responsible for the lean BM preservation despite sustained high levels of caloric expenditure and extremely cold conditions.…”

“…To date, there is a limited number of studies on ultra-endurance athletes competing in cold temperatures ranging from -21°C to -2°C (Stuempfle et al, 2002, 2003; Chlíbková et al, 2019) and under very cold weather conditions with temperatures down to -48°C (O’Hara et al, 1977; Paulin et al, 2015; Coker et al, 2017; Johannsen et al, 2018; Schalt et al, 2018).…”