Total Energy Expenditure and Nutritional Intake in Continuous Multiday Ultramarathon Events.

Continuous multiday ultramarathon competitions are increasingly popular and impose extreme energetic and nutritional demands on competitors. However, few data have been published on energy expenditure during these events. Here, we report doubly labeled water-derived measures of total energy expenditure (in kilocalories per day) and estimated physical activity level (PAL: total energy expenditure/basal metabolic rate) collected from five elite and subelite finishers (four males and one female, age 34.6 ± 4.9 years)-and nutritional intake data from the winner-of the Cocodona 250, a ∼402-km race in Arizona, and from a fastest-known-time record (one male, age 30 years) on the ∼1,315-km Arizona Trail. PAL during these events exceeded four times basal metabolic rate (Cocodona range: 4.34-6.94; Arizona Trail: 5.63). Combining the results with other doubly labeled water-derived total energy expenditure data from ultraendurance events show a strong inverse relationship between event duration and PAL (r2 = .68, p < .0001). Cocodona race duration was inversely, though not significantly, associated with PAL (r2 = .70, p = .08). Water turnover varied widely between athletes and was not explained by PAL or body mass. The Cocodona race winner met ∼53% of energy demand via dietary intake, 85.6% of which was carbohydrate, while ∼47% of energy demand was met via catabolism of body energy stores. Together, these results illustrate the energetic deficits incurred during competitive continuous multiday ultramarathon efforts and implicate macronutrient absorption and/or storage as key factors in ultramarathon performance.

Reindeer herders from subarctic Finland exhibit high total energy expenditure and low energy intake during the autumn herd roundup.

OBJECTIVE: High levels of total energy expenditure (TEE, kcal/day) have been documented among numerous human populations such as tropical climate horticulturalists and high-altitude agriculturalists. However, less work has been conducted among highly physically active cold climate populations. METHODS: In October 2018, TEE was measured using the doubly labeled water (TEEDLW , N = 10) and flex-heart rate methods (TEEHR , N = 24) for 6-14 days among reindeer herders (20-62 years) in northern Finland during an especially physically demanding, but not seasonally representative, period of the year for herders-the annual reindeer herd roundup. Self-reported dietary intake was also collected during TEE measurement periods. TEE was then compared to that of hunter gatherer, farming, and market economies. RESULTS: During the herd roundup, herders expended a mean of 4183 ± 949 kcal/day as measured by the DLW method, which was not significantly different from TEEHR . Mean caloric intake was 1718 ± 709 kcal/day, and was significantly lower than TEEDLW and TEEHR (p < .001). Herder TEEDLW was significantly higher than that of hunter gatherer (p = .0014) and market (p < .0014) economy populations; however, herder TEEDLW was not different from that of farming populations (p = .91). CONCLUSION: High TEE and low caloric intake among herders reflect the extreme demands placed on herders during the annual herd round up. Although TEEDLW was similar between cold climate herders and hot climate farming populations, there are likely differences in how that TEE is comprised, reflecting the local ecologies of these populations.

Sex differences and shifts in body composition, physical activity, and total energy expenditure across a 3-month expedition.

OBJECTIVES: An energetically demanding environment like a wilderness expedition can lead to potent stressors on human physiology and homeostatic balance causing shifts in energy expenditure and body composition. These shifts likely have consequences on overall health and performance and may potentially differ by sex. It is therefore critical to understand the potential differential body composition and energy expenditure changes in response to a novel and challenging environment in both males and female bodies. METHODS: Data were collected from 75 healthy individuals (female = 41; ages 18-53) throughout a 3-month long expedition in the American Rockies. Body mass, body fat, and lean muscle mass were measured before, during, and after the course. Physical activity intensity and energy expenditure were also measured in a subset of participants using the wGT3X-BT Actigraph wrist monitor and an accompanying Bluetooth heart rate monitor. RESULTS: Over the 3-month period, individuals initially experienced declines in body mass, body fat percentage, and lean muscle mass. Participants partially rebounded from these deficits to maintain overall body mass with a slight recomposition of body fat and lean muscle mass. Our data also demonstrated that sex moderated total energy expenditure, where females experienced a modest decline whereas males experienced an increase in energy expenditure from the beginning to the end of the course. CONCLUSIONS: Understanding changes in energy storage in the body and variation in energy expenditure between sexes during a 3-month expedition has critical implications for maintaining health and performance in an energetically demanding environment where resources may be scarce.

Extreme events reveal an alimentary limit on sustained maximal human energy expenditure.

The limits on maximum sustained energy expenditure are unclear but are of interest because they constrain reproduction, thermoregulation, and physical activity. Here, we show that sustained expenditure in humans, measured as maximum sustained metabolic scope (SusMS), is a function of event duration. We compiled measurements of total energy expenditure (TEE) and basal metabolic rate (BMR) from human endurance events and added new data from adults running ~250 km/week for 20 weeks in a transcontinental race. For events lasting 0.5 to 250+ days, SusMS decreases curvilinearly with event duration, plateauing below 3× BMR. This relationship differs from that of shorter events (e.g., marathons). Incorporating data from overfeeding studies, we find evidence for an alimentary energy supply limit in humans of ~2.5× BMR; greater expenditure requires drawing down the body's energy stores. Transcontinental race data suggest that humans can partially reduce TEE during long events to extend endurance.

Human energy expenditure, allocation, and interactions in natural temperate, hot, and cold environments.

OBJECTIVE: The aim of this research is to analyze how energy is allocated differently in temperate, hot, and cold environments among National Outdoor Leadership School students. METHOD: Basal metabolic rate, physical activity, thermoregulation, and the thermic effect of food were estimated to determine the total energy expenditure and energy allocation differences among a group of healthy, highly active adults (N = 59) participating in National Outdoor Leadership School courses in the western United States. Two of these courses took place in both hot and temperate climates (N = 22) and the other two in both temperate and cold climates (N = 28). Data from a pilot study (N = 6) in a temperate climate were also included. Each climate regime lasted for one month. RESULTS: Total energy expenditure values were statistically equivalent in temperate and hot climates (p = .97). However, subjects experienced significantly higher total energy expenditures in cold climates (p < .0001), expending an additional ∼1550 kcal day-1 . There is a significant interaction between physical activity and thermoregulation, such that physical activity reduces thermoregulatory costs in cold climates, but increases it in hot climates. CONCLUSIONS: Dissection of the energy budget revealed that total energy expenditure is significantly higher in cold climates. This is due to a combination of high levels of physical activity and high thermoregulatory costs. High levels of physical activity may substantially lower the cost of thermoregulation in cold climates, and this interaction should be taken into account when estimating TEE.

The allocation and interaction model: A new model for predicting total energy expenditure of highly active humans in natural environments.

OBJECTIVE: The purpose of this study was to develop a new model, the Allocation and Interaction Model (AIM), to better predict human total energy expenditure (TEE) among a group of highly active humans living in a variety of natural environments. AIM estimates were tested to determine if it produces more accurate TEE predictions than the Factorial Method. METHODS: AIM includes metabolic cost terms for basal metabolic rate, thermoregulation, and the thermic effect of food, as well as more accurate activity cost estimations. AIM was tested using doubly labeled water and Flex-Heart Rate (Flex-HR)-measured TEEs of healthy, highly active adults (N = 59) participating in National Outdoor Leadership School semester-long courses. Data from a month-long pilot study (N = 6) were also included. RESULTS: AIM produced TEE estimates that were not significantly different from measured energy expenditure values. Overall, AIM came within 4.1% of measured values; the Factorial Method underestimated by over 25%. At TEEs greater than 3,000 kcal day(-1) , AIM underestimated TEE by 11% compared to 31.6% by the Factorial Method. Also, at TEEs greater than 3,000 kcal day(-1) , the Flex-HR method overestimated TEE by 17%. CONCLUSIONS: This analysis demonstrated that AIM is more accurate than the Factorial Method for predicting TEE across a range of climates and physical activity levels. This suggests that AIM should be used in place of the Factorial Method for estimating human TEE. Am. J. Hum. Biol. 28:372-380, 2016. © 2015 Wiley Periodicals, Inc.