The aim of this study was to evaluate age-related changes in lumbar paravertebral muscle (LPM) morphology in healthy younger and older adult men.T2-weighted axial MRI of the lumbar spine were obtai...

This study investigates differences in pre- to post-expedition energy expenditure, substrate utilisation and body composition, between the all-male Spear17 (SP-17) and all-female Ice Maiden (IM) transantarctic expeditions (IM: N = 6, 61 days, 1700 km; SP-17: N = 5, 67 days, 1750 km). Energy expenditure and substrate utilisation were measured by a standardised 36 h calorimetry protocol; body composition was determined using air displacement plethysmography. Energy balance calculation were used to assess the physical challenge. There was difference in the daily energy expenditure (IM: 4,939 kcal day⁻¹; SP-17: 6,461 kcal day⁻¹, p = 0.004); differences related to physical activity were small, but statistically significant (IM = 2,282 kcal day⁻¹; SP-17 = 3,174 kcal day⁻¹; p = 0.004). Bodyweight loss was modest (IM = 7.8%, SP-17 = 6.5%; p > 0.05) as was fat loss (IM = 30.4%, SP-17 = 40.4%; p > 0.05). Lean tissue weight change was statistically significant (IM = − 2.5%, SP-17 = + 1.0%; p = 0.05). No difference was found in resting or sleeping energy expenditure, normalised to lean tissue weight (p > 0.05); nor in energy expenditure when exercising at 80, 100 and 120 steps min⁻¹, normalised to body weight (p > 0.05). Similarly, no difference was found in the change in normalised substrate utilisation for any of the activities (p > 0.05). Analysis suggested that higher daily energy expenditures for the men in Spear-17 was the result of higher physical demands resulting in a reduced demand for energy to thermoregulate compared to the women in Ice Maiden. The lack of differences between men and women in the change in energy expenditure and substrate utilisation, suggests no sex difference in response to exposure to extreme environments.

This paper reports the metabolic energy changes in six women who made the first unsupported traverse of Antarctica covering a distance of 1700km in 61 days hauling sledges weighing up to 80kg. Pre- and post-expedition, measurements of energy expenditure and substrate utilisation were made on all 6 members of the expedition over a 36hr period in a whole body calorimeter. During the study, subjects were fed an isocaloric diet: 50% carbohydrate, 35% fat and 15% protein. The experimental protocol contained pre and post-expedition measurement including periods of sleep, rest and three periods of standardised stepping exercise at 80, 100 and 120 steps min^-1. A median (IQR) decrease in the lean and fat weight of the subjects of 1.4 (1.0)kg and 4.4 (1.8) kg, respectively (p<0.05) was found, using air-displacement plethysmography. No statistically significant difference was found between pre- and post -expedition values for sleeping or resting metabolic rate nor for diet induced thermogenesis. A statistically significant difference was found in energy expenditure between the pre- and post-expedition values for exercise at 100 [4.7 (0.23) vs 4.4 (0.29), p<0.05] and 120 [5.7 (0.46) vs 5.5 (0.43), p<0.05] steps min^-1; a difference which disappeared when the metabolic rate values were normalised to body weight. The group was well matched for the measures studied. Whilst a physiological change in weight was seen the lack of change in metabolic rate measures supports a view that women appropriately nourished and well prepared can undertake polar expeditions with a minimal metabolic energy consequence.

The energy expenditure and substrate utilisation were measured in 5 men pre- and post- a 67 day, 1750km unassisted Antarctic traverse from the Hercules Inlet to the Ross Sea Ice via the South pole pulling sledges weighing 120kg whilst experiencing temperatures as low as -57°C. A 36-hours protocol in a whole body calorimeter was employed to measure periods of rest, sleep and three periods of standardised stepping exercises at 80, 100 and 120 steps min-1; participants were fed isocalorically. Unlike previous expeditions where large weight loss was reported, only a modest loss of body weight (7%, P = 0.03) was found; fat tissue was reduced by 53% (P = 0.03) together with a small, but not statistically significant, increase in lean tissue weight (P = 0.18). This loss occurred despite a high-energy intake (6500 kcal/day) designed to match energy expenditure. An energy balance analysis suggested the loss in body weight could be due to the energy requirements of thermoregulation. Differences in energy expenditure [4.9 (0.1) vs 4.5 (0.1) kcal/min. P = 0.03], carbohydrate utilisation [450 (180) vs 569 (195) g/day; P = 0.03] and lipid utilisation [450 (61) vs 388 (127) g/day, P = 0.03] at low levels of exertion were different from pre-expedition values. Only carbohydrate utilisation remained statistically significant when normalised to body weight. The differences in energy expenditure and substrate utilisation between the pre- and post-expedition for other physiological states (sleeping, resting, higher levels of exercise, etc) were small and not statistically significant. Whilst inter-subject variability was large, there was a tendency for increased carbohydrate utilisation, post-expedition, when fasted that decreased upon feeding.

Purpose: To investigate changes in 24‐h energy expenditure (EE), substrate oxidation, and body composition following resistance exercise (RE) and a high protein diet via whey protein supplementation (alone and combined) in healthy older men.Methods: In a pooled groups analysis, 33 healthy older men [(mean ± SE) age: 67 ± 1 years; BMI: 25.4 ± 0.4 kg/m²] were randomized to either RE (2×/week; n = 17) or non‐exercise (n = 16) and either a high protein diet via whey protein supplementation (PRO, 2 × 25 g whey protein isolate/d; n = 17) or control (CON, 2 × 23.75 g maltodextrin/d; n = 16). An exploratory sub‐analysis was also conducted between RE+CON (n = 8) and RE+PRO (n = 9). At baseline and 12 weeks, participants resided in respiration chambers for measurement of 24‐h EE and substrate oxidation and wore an accelerometer for 7 days for estimation of free‐living EE.Results: Resistance exercise resulted in greater increases in fat‐free mass (1.0 ± 0.3 kg), resting metabolic rate [(RMR) 36 ± 14 kcal/d], sedentary EE (60 ± 33 kcal/d), and sleeping metabolic rate [(SMR) 45 ± 7 kcal/d] compared to non‐exercise (p < 0.05); however, RE decreased activity energy expenditure in free‐living (−90 ± 25 kcal/d; p = 0.049) and non‐exercise activity inside the respiration chamber (−1.9 ± 1.1%; p = 0.049). PRO decreased fat mass [(FM) −0.5 ± 0.3 kg], increased overnight protein oxidation (30 ± 6 g/d), and decreased 24‐h protein balance (−20 ± 4 g/d) greater than CON (p < 0.05). RE+PRO decreased FM (−1.0 ± 0.5 kg) greater than RE+CON (p = 0.04).Conclusion: Resistance exercise significantly increased RMR, SMR, and sedentary EE in healthy older men, but not total EE. PRO alone and combined with RE decreased FM and aided body weight maintenance. This study was registered at clinicaltrials.gov as NCT03299972.

Antarctic expeditions present extreme physiological challenges due to cold temperatures, high physical exertion, and 24-hour daylight. This observational study evaluated endocrine adaptation in nine participants (six men, three women) during a 47-day, 1,000 km unassisted ski traverse. Detailed salivary sampling was conducted before, during and after the expedition, corroborated by blood and hair sampling before and after the expedition. Cortisol, testosterone, and androstenedione were measured using mass spectrometry, and thyroid hormones via immunoassay. Diurnal cortisol, androstenedione and testosterone variation was preserved, while the morning cortisol increased during the expedition, suggesting that exercise demands overshadow the effects of continuous daylight in controlling hypothalamic-pituitary-adrenal and gonadal axis function. Morning testosterone decreased during the expedition, with a greater effect seen among men. No significant changes were seen in blood or hair steroid hormones. Gonadotropins in women indicated central suppression pre-expedition, normalizing post-expedition. Thyroid-stimulating hormone levels increased post-expedition without significant changes in free T3 or T4, consistent with mild polar T3 syndrome. These findings highlight the adaptability of hypothalamic-pituitary function to combined stressors of exercise, energy deficit, and cold. This is the first study to capture in situ endocrine responses during an Antarctic traverse, advancing our understanding of human adaptation in extreme environments.