The purpose of this study was to examine the effects of acute normobaric (NH, decreased FiO2) and hypobaric (HH, 4200 m ascent) hypoxia exposures compared to sea level (normobaric normoxia, NN). Tissue oxygenation, cardiovascular, and body fluid variables measured during rest and a 3-min step-test following 90-min exposures (NH, HH, NN). Muscle oxygenated hemoglobin (O2Hb) decreased, and muscle deoxygenated hemoglobin (HHb) increased environmentally independent from rest to exercise (p < 0.001). During exercise, brain O2Hb was lower at HH compared to NN (p = 0.007), trending similarly with NH (p = 0.066), but no difference between NN and NH (p = 0.158). During exercise, HR at NH (141 ± 4 beats·min−1) and HH (141 ± 3 beats·min−1) were higher than NN (127 ± 44 beats·min−1, p = 0.002), but not each other (p = 0.208). During exercise, stroke volume at HH (109.6 ± 4.1 mL·beat−1) was higher than NH (97.8 ± 3.3 mL·beat−1) and NN (99.8 ± 3.9 mL·beat−1, p ≤ 0.010) with no difference between NH and NN (p = 0.481). During exercise, cardiac output at NH (13.8 ± 0.6 L) and HH (15.5 ± 0.7 L) were higher than NN (12.6 ± 0.5 L, p ≤ 0.006) with HH also higher than NH (p = 0.001). During acute hypoxic stimuli, skeletal muscle maintains oxygenation whereas the brain does not. These differences may be mediated by environmentally specific cardiovascular compensation. Thus, caution is advised when equating NH and HH.
Purpose Research has elucidated the impact of post-exercise carbohydrate nutrition and environmental conditions on muscle glycogen re-synthesis. However, research has minimally considered the implications of glycogen recovery in females and has mostly focused on commercial sport nutrition products. The purpose of this study was to determine the effects of varied mixed macronutrient feedings on glycogen recovery and subsequent exercise performance in both sexes. Methods Males (n = 8) and females (n = 8) participated in a crossover study. Subjects completed a 90-min cycling glycogen depletion trial, then rested for 4 h. Two carbohydrate feedings (1.6 g kg −1) of either sport supplements or potato-based products were delivered at 0 and 2 h post-exercise. Muscle biopsies (glycogen) and blood samples (glucose, insulin) were collected during the recovery. Afterwards, subjects completed a 20 km cycling time trial. Results There was no difference between sexes or trials for glycogen recovery rates (male: 7.9 ± 2.7, female: 8.2 ± 2.7, potato-based: 8.0 ± 2.5, sport supplement: 8.1 ± 3.1 mM kg wet wt −1 h −1 , p > 0.05). Time trial performance was not different between diets (38.3 ± 4.4 and 37.8 ± 3.9 min for potato and sport supplement, respectively, p > 0.05). Conclusions These results indicate that food items, such as potato-based products, can be as effective as commercially marketed sports supplements when developing glycogen recovery oriented menus and that absolute carbohydrate dose feedings (g kg −1) can be effectively applied to both males and females.
Objective: Document wildland firefighters (WLFFs) hydration status during a singular workshift (13.7 AE 1.4 hours). Methods: WLFF researchers documented real-time WLFF (n ¼ 71) urine metrics and fluid consumption. Body weight and blood samples (n ¼ 25) were also collected. Two-tailed dependent t tests determined statistical significance (P < 0.05). Results: Body weight significantly decreased (À0.3 AE 1.1%, P > 0.05). Fluid consumption totaled 6.2 AE 2.3 L including food and 5.0 AE 2.1 L without food. Morning versus afternoon urine frequency (2.6 AE 1.3, 3.1 AE 1.9 voids), urine volume (1.2 AE 0.7, 1.3 AE 0.8 L), urine volume per void (440 AE 157, 397 AE 142 mL), and urine specific gravity (1.010 AE 0.007, 1.010 AE 0.007) were not significantly different (P > 0.05). Pre-to post-workshift serum chloride (103.2 AE 1.9, 101.4 AE 1.7 mM) and blood glucose (5.2 AE 0.4, 4.5 AE 0.7 mM) significantly decreased (P < 0.05), while serum sodium (141.5 AE 2.4, 140.8 AE 2.0 mM) and serum potassium (4.3 AE 0.3, 4.2 AE 0.3 mM) remained stable (P > 0.05). Conclusions: WLFFs can ingest fluid and food amounts that maintain workshift euhydration and electrolyte status.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.