Physiological Responses and Physical Performance during Football in the Heat

PURPOSE: To examine the impact of hot ambient conditions on physical performance and physiological responses during football match-play. METHODS: Two experimental games were completed in temperate (∼ 21°C; CON) and hot ambient conditions (∼ 43°C; HOT). Physical performance was assessed by match analysis in 17 male elite players during the games and a repeated sprint test was conducted after the two game trials. Core and muscle temperature were measured and blood samples were obtained, before and after the games. RESULTS: Muscle and core temperatures were ∼ 1°C higher (P<0.05) in HOT (40.3 ± 0.1 and 39.5 ± 0.1°C, respectively) compared to CON (39.2 ± 0.1 and 38.3 ± 0.1°C). Average heart rate, plasma lactate concentration, body weight loss as well as post-game sprint performance were similar between the two conditions. Total game distance declined (P<0.05) by 7% and high intensity running (>14 km ⋅ h(-1)) by 26% in HOT compared to CON), but peak sprint speed was 4% higher (P<0.05) in HOT than in CON, while there were no differences in the quantity or length of sprints (>24 km ⋅ h(-1)) between CON and HOT. In HOT, success rates for passes and crosses were 8 and 9% higher (P<0.05), respectively, compared to CON. Delta increase in core temperature and absolute core temperature in HOT were correlated to total game distance in the heat (r = 0.85 and r = 0.53, respectively; P<0.05), whereas, total and high intensity distance deficit between CON and HOT were not correlated to absolute or delta changes in muscle or core temperature. CONCLUSION: Total game distance and especially high intensity running were lower during a football game in the heat, but these changes were not directly related to the absolute or relative changes in core or muscle temperature. However, peak sprinting speed and execution of successful passes and crosses were improved in the HOT condition

The comparison of fertilization-triggered membrane potential changes of the eggs belong to internally and externally fertilizing organisms

Experimental Biology 2005 Meeting/35th International Congress of Physiological Sciences -- MAR 31-APR 06, 2005 -- San Diego, CAWOS: 000227610701352…Amer Assoc Anatomists, Amer Assoc Immunol, Amer Phtsiol Soc & Int Union Physiol Sci, Amer Soc Biochem & Mole Biol, Amer Soc Investigat Pathol, Amer Soc Nutr Sci, Amer Soc Pharmacol & Exptl Therapeu

Individual fluid plans versus ad libitum on hydration status in minor professional ice hockey players

Abstract Background Despite exercising in cool environments, ice hockey players exhibit several dehydration risk factors. Individualized fluid plans (IFPs) are designed to mitigate dehydration by matching an individual’s sweat loss in order to optimize physiological systems and performance. Methods A randomized control trial was used to examine IFP versus ad libitum fluid ingestion on hydration in 11 male minor professional ice hockey players (mean age = 24.4 ± 2.6 years, height = 183.0 ± 4.6 cm, weight = 92.9 ± 7.8 kg). Following baseline measures over 2 practices, participants were randomly assigned to either control (CON) or intervention (INT) for 10 additional practices. CON participants were provided water and/or carbohydrate electrolyte beverage to drink ad libitum. INT participants were instructed to consume water and an electrolyte-enhanced carbohydrate electrolyte beverage to match sweat and sodium losses. Urine specific gravity, urine color, and percent body mass change characterized hydration status. Total fluid consumed during practice was assessed. Results INT consumed significantly more fluid than CON (1180.8 ± 579.0 ml vs. 788.6 ± 399.7 ml, p = 0.002). However, CON participants replaced only 25.4 ± 12.9% of their fluid needs and INT 35.8 ± 17.5%. Mean percent body mass loss was not significantly different between groups and overall indicated minimal dehydration (<1.2% loss). Pre-practice urine specific gravity indicated CON and INT began hypohydrated (mean = 1.024 ± 0.007 and 1.024 ± 0.006, respectively) and experienced dehydration during practice (post = 1.026 ± 0.006 and 1.027 ± 0.005, respectively, p < 0.001). Urine color increased pre- to post-practice for CON (5 ± 2 to 6 ± 1, p < 0.001) and INT (5 ± 1 to 6 ± 1, p < 0.001). Conclusions Participants consistently reported to practice hypohydrated. Ad libitum fluid intake was not significantly different than IFP on hydration status. Based on urine measures, both methods were unsuccessful in preventing dehydration during practice, suggesting practice-only hydration is inadequate to maintain euhydration in this population when beginning hypohydrated