Alaska Mountain Wilderness Ski Classic: Alterations in Caloric Expenditure and Body Composition

Alaska backcountry expeditionary hunting promotes rapid improvements in metabolic biomarkers in healthy males and females

We have previously reported negative energy balance and health benefits during an Alaska backcountry expeditionary hunting (ABEH) immersion in two males. The purpose of our present study was to increase the number of participants, include females, and evaluate macronutrient intake and serum lipids. Four men (age: 46 ± 6 year, BMI: 26 ± 1 kg/m2 ) and three women (age: 46 ± 11 year, BMI: 25 ± 3 kg/m2 ) were recruited. Doubly labeled water methodology and dietary recall were utilized to assess energy expenditure and energy intake, respectively. Data were collected during pre- and post-ABEH visits. Body composition was measured using dual-energy x-ray absorptiometry and the cross-sectional area of skeletal muscle in the upper leg (XT), and intrahepatic lipid (IHL) was determined using magnetic resonance imaging and/or spectroscopy (MRI/MRS). Blood parameters were measured by LabCorp. Paired T-tests were used for statistical analysis. Data are reported as mean ± SD and considered significant at p < 0.05. Total energy intake was 7.7 ± 3.4 MJ/day and total energy expenditure was 17.4 ± 2.6 MJ/day, resulting in a negative energy balance of -9.7 ± 3.4 MJ/day. Protein intake(grams)/body weight(kilograms)/day was 1.0 ± 0.4. There were reductions in body weight (Δ-1.5 ± 0.7 kg), BMI (Δ-0.3 ± 0.2 kg/m2 ), fat mass (Δ-1.7 ± 0.9 kg), and IHL (Δ-0.3 ± 0.3% water peak). There were no changes in lean tissue mass (Δ0.6 ± 1.4 kg) or XT (Δ-1.3 ± 3.3 cm2 ). There were significant reductions in total cholesterol (Δ-44 ± 35 mg/dl), LDL-cholesterol (Δ-25 ± 14 mg/dl), VLDL-cholesterol (Δ-7 ± 7 mg/dl), and triglycerides (Δ-35 ± 33 mg/dl). The ABEH immersion resulted in considerable negative energy balance and provided comprehensive benefits in metabolic health without any reduction in skeletal muscle.

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

Background: To date, no study has focused on body composition characteristics and on parameters associated with skeletal muscle damage and renal function in runners participating in a 24-h winter race held under extremely cold environmental conditions (average temperature of -14.3°C). Methods: Anthropometric characteristics, plasma urea (PU), plasma creatinine (Pcr), creatine kinase (CK), plasma volume (PV) and total body water (TBW) were assessed pre- and post-race in 20 finishers (14 men and 6 women). Results: In male runners, body mass (BM) (p = 0.003) and body fat (BF) (p = 0.001) decreased [-1.1 kg (-1.4%) and -1.1 kg (-13.4%), respectively]; skeletal muscle mass (SM) and TBW remained stable (p > 0.05). In female runners, BF decreased (p = 0.036) [-1.3 kg (-7.8%)] while BM, SM and TBW remained stable (p > 0.05). The change (Δ) in BM was not related to Δ BF; however, Δ BM was related to Δ SM [r = 0.58, p = 0.007] and Δ TBW (r = 0.59, p = 0.007). Δ SM correlated with Δ TBW (r = 0.51, p = 0.021). Moreover, Δ BF was negatively associated with Δ SM (r = -0.65, p = 0.002). PV (p < 0.001), CK (p < 0.001), Pcr (p = 0.004) and PU (p < 0.001) increased and creatinine clearance (CrCl) decreased (p = 0.002). The decrease in BM was negatively related to the increase in CK (r = -0.71, p < 0.001). Δ Pcr was positively related to Δ PU (r = 0.64, p = 0.002). The decrease in CrCl was negatively associated with the increase in both PU (r = -0.72, p < 0.001) and CK (r = -0.48, p = 0.032). Conclusion: The 24-h running race under extremely cold conditions led to a significant BF decrease, whereas SM and TBW remained stable in both males and females. Nevertheless, the increase in CK, Pcr and PU was related to the damage of SM with transient impaired renal function.

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

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.

The energy requirements and metabolic benefits of wilderness hunting in Alaska

The purported healthy aspects of subsistence foods have led to the popularity of the Paleo diet. There has been very little focus, surprisingly, on health benefits derived from the nomadic nature of humans during the Paleolithic era. The purpose of our study was to examine total energy expenditure (TEE), total energy intake (TEI), body composition, blood lipids, and intrahepatic lipid in humans during a 12-day Alaskan backcountry expeditionary hunting (ABEH) immersion. Four healthy men (age: 42 ± 3 year, BMI: 27 ± 1 kg/m2 ) were recruited for the study. TEE was measured using the doubly labeled water method and a food diary was utilized to assess TEI. Body composition was measured using dual energy X-ray absorptiometry (DXA); cross-sectional area of the thigh (XT) and intrahepatic lipid (IHL) were measured using molecular imaging. Blood samples were collected for the measurement of blood lipids. DXA, XT, IHL, and blood data were collected pre- and immediately post-ABEH. Results were analyzed using paired t-tests and considered significant at P < 0.05. TEE and TEI averaged 18.1 ± 1.2 and 9.1 ± 2.5 MJ/day, respectively, indicating substantial negative energy balance (-9.0 ± 1.3 MJ/day). There was a reduction in percent body fat (∆-3.3 ± 0.2%), total fat mass (∆-3.3 ± 0.4 kg), and visceral fat volume (Δ-261 ± 188 cm3 ). Lean tissue mass and XT was unchanged. There was a decrease in IHL (Δ-0.5 ± 0.1% water peak), and a trend (P = 0.055) toward reduction in LDL-cholesterol. We conclude that constancy of physical activity during negative energy balance may provide metabolic benefits above and beyond variations in diet that exist with the hunter-gatherer lifestyle.