RESUMEN
Previous studies have used the doubly labeled water method to evaluate the total energy expenditure (TEE) during Ironman, ultramarathon trail runs, and competitive road cycling. However, the technique has not been applied to a 24-hour cross-country mountain-bike event. PURPOSE: This case study aimed to measure the TEE, cycling metrics, and ad libitum nutrient/fluid intake during a 24-hour cross-country mountain-bike race. METHODS: A trained male cyclist (41 y, 74.1 kg, 172.4 cm) received an oral dose of doubly labeled water prior to the 24-hour event for the calculations of TEE and water turnover. Nude body weight and urine samples were collected prerace, during the race, and postrace. Total nutrient intake and total fluid intake in addition to cycling metrics (speed, power output, cadence, and heart rate) were continuously recorded during the event. RESULTS: The rider completed 383 km coupled with a vertical gain of 7737 m during the 24-hour event. Average speed, power, and heart rate were 16.3 (2) km·h-1, 122 (29) W, and 134 (18) beats·min-1, respectively. TEE and total nutrient intake were 41 and 23.5 MJ, respectively. Total carbohydrate intake was 1192 g with an average hourly intake of 58 (22) g·h-1. Total body weight was 75.3 and 72.3 kg prerace and postrace, respectively, with a measured ad libitum total fluid intake of 13.3 L and a water turnover of 17.2 L. CONCLUSIONS: These data provide novel insights for measures of TEE, total energy intake, and total fluid intake during an ultraendurance cross-country mountain-biking event and provide a foundation for future race/training needs.
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Ciclismo , Ingestión de Energía , Humanos , Masculino , Ciclismo/fisiología , Ingestión de Alimentos , Agua , Nutrientes , Peso Corporal/fisiología , Metabolismo Energético/fisiologíaRESUMEN
OBJECTIVE: Determine serum lipid and general health/fitness alterations following a 5-month wildfire suppression season. METHODS: We recruited 100 wildland firefighters (WLFFs) to a 5-month pre- to post-season observational study. Nude body mass, blood pressure (BP), grip strength, and steptest heart rate (HR) were recorded. Blood samples were collected for lipid panel analysis (total cholesterol, high density lipoproteins (HDL)-cholesterol, low density lipoproteins-cholesterol, very low density lipoproteinscholesterol, triglycerides, triglyceride:HDL-cholesterol ratio). Two-tailed dependent t tests determined statistical significance (Pâ<â0.05). RESULTS: There were pre- to post-season changes in nude body mass (+2â±â4%, Pâ =â0.001), systolic BP (-2â±â10%, Pâ =â0.01), step-test HR (-5â±â10%, Pâ <â0.001), and all serum lipids (total cholesterol: +5â±â14%, Pâ =â0.02, HDL-cholesterol:â=â1â±â17%, Pâ =â0.04, low density lipoproteins-cholesterol: +8â±â22%, Pâ =â0.02, very low density lipoproteins-cholesterol: +31â±â49%, Pâ <â0.001, triglycerides: +30â±â49%, Pâ <â0.001, triglyceride:HDL-cholesterol ratio: +37â±â58%, Pâ <â0.001). Pre- to post-season diastolic BP (Pâ=â0.12) and grip strength (Pâ=â0.60) remained stable. CONCLUSIONS: WLFFs demonstrate maladaptive serum lipids and body mass alterations despite subtle aerobic fitness improvements.
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Bomberos , Metabolismo de los Lípidos , Aptitud Física , HDL-Colesterol , LDL-Colesterol , Humanos , Triglicéridos , Incendios ForestalesRESUMEN
OBJECTIVE: Document wildland firefighters (WLFFs) hydration status during a singular workshift (13.7â±â1.4âhours). METHODS: WLFF researchers documented real-time WLFF (nâ=â71) urine metrics and fluid consumption. Body weight and blood samples (nâ=â25) were also collected. Two-tailed dependent t tests determined statistical significance (Pâ<â0.05). RESULTS: Body weight significantly decreased (-0.3â±â1.1%, Pâ>â0.05). Fluid consumption totaled 6.2â±â2.3âL including food and 5.0â±â2.1âL without food. Morning versus afternoon urine frequency (2.6â±â1.3, 3.1â±â1.9 voids), urine volume (1.2â±â0.7, 1.3â±â0.8âL), urine volume per void (440â±â157, 397â±â142âmL), and urine specific gravity (1.010â±â0.007, 1.010â±â0.007) were not significantly different (Pâ>â0.05). Pre- to post-workshift serum chloride (103.2â±â1.9, 101.4â±â1.7âmM) and blood glucose (5.2â±â0.4, 4.5â±â0.7âmM) significantly decreased (Pâ<â0.05), while serum sodium (141.5â±â2.4, 140.8â±â2.0âmM) and serum potassium (4.3â±â0.3, 4.2â±â0.3âmM) remained stable (Pâ>â0.05). CONCLUSIONS: WLFFs can ingest fluid and food amounts that maintain workshift euhydration and electrolyte status.
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Bomberos , Incendios Forestales , Peso Corporal , Deshidratación , Humanos , UrinálisisRESUMEN
INTRODUCTION: Wildfire suppression is characterized by high total energy expenditure and water turnover rates. Hydration position stands outline hourly fluid intake rates. However, dose interval remains ambiguous. We aimed to determine the effects of microdosing and bolus-dosing water and microdosing and bolus-dosing carbohydrate-electrolyte solutions on fluid balance, heat stress (physiologic strain index [PSI]), and carbohydrate oxidation during extended thermal exercise. METHODS: In a repeated-measures cross-over design, subjects completed four 120-min treadmill trials (1.3 m·s-1, 5% grade, 33°C, 30% relative humidity) wearing a US Forest Service wildland firefighter uniform and a 15-kg pack. Fluid delivery approximated losses calculated from a pre-experiment familiarization trial, providing 22 doses·h-1 or 1 dose·h-1 (46±11, 1005±245 mL·dose-1). Body weight (pre- and postexercise) and urine volume (pre-, during, and postexercise) were recorded. Heart rate, rectal temperature, skin temperature, and steady-state expired air samples were recorded throughout exercise. Statistical significance (P<0.05) was determined via repeated-measures analysis of variance. RESULTS: Total body weight loss (n=11, -0.6±0.3 kg, P>0.05) and cumulative urine output (n=11, 677±440 mL, P>0.05) were not different across trials. The micro-dosed carbohydrate-electrolyte trial sweat rate was lower than that of the bolus-dosed carbohydrate-electrolyte, bolus-dosed water, and microdosed water trials (n=11, 0.8±0.2, 0.9±0.2, 0.9±0.2, 0.9±0.2 L·h-1, respectively; P<0.05). PSI was lower at 60 than 120 min (n=12, 3.6±0.7 and 4.5±0.9, respectively; P<0.05), with no differences across trials. The carbohydrate-electrolyte trial's carbohydrate oxidation was higher than water trial's (n=12, 1.5±0.3 and 0.8±0.2 g·min-1, respectively; P<0.05), with no dosing style differences. CONCLUSIONS: Equal-volume diverse fluid delivery schedules did not affect fluid balance, PSI, or carbohydrate oxidation during extended thermal work.
Asunto(s)
Ingestión de Líquidos , Ejercicio Físico , Respuesta al Choque Térmico , Equilibrio Hidroelectrolítico , Agua , Adulto , Temperatura Corporal , Metabolismo de los Hidratos de Carbono , Estudios Cruzados , Fluidoterapia , Calor , HumanosRESUMEN
The mechanism of ISA23 · HCl interaction with model membrane vesicles (80-100 nm in diameter) was investigated using EPR in conjunction with SANS. For EPR, 16-DSE was dissolved in the vesicle membrane to measure its dynamics and polarity, whereas a spin-labeled (Tempo)-ISA 23 analogue was used to give a measure of the polymer flexibility. When ISA23 was added to the external vesicle surface, no interaction was found. This observation conflicts with the reported ability to lyse RBC, but is in agreement with recent studies that showed no effect on membrane permeability when a PAA was added to an incubation medium containing isolated lysosomal vesicles. The vesicle-mimetic models used here provide a new and useful tool for studying endosomolytic polymer/membrane interactions.