Drinking behaviors of elite male runners during marathon competition.

OBJECTIVE: To describe the drinking behaviors of elite male marathon runners during major city marathons. DESIGN: Retrospective analysis of drinking behaviors. SETTING: Institutional. PARTICIPANTS: Ten (9 winners and 1 second position) male marathon runners during 13 major city marathons. MAIN OUTCOME MEASURES: Total drinking durations and fluid intake rates during major city marathons. RESULTS: The ambient conditions during the 13 studied marathon races were 15.3°C ± 8.6°C and 59% ± 17% relative humidity; average marathon competition time was 02:06:31 ± 00:01:08 (hours:minutes:seconds). Total drinking duration during these races was 25.5 ± 15.0 seconds (range, 1.6-50.7 seconds) equating to an extrapolated fluid intake rate of 0.55 ± 0.34 L/h (range, 0.03-1.09 L/h). No significant correlations were found between total drink duration, fluid intake (rate and total), running speed, and ambient temperature. Estimated body mass (BM) loss based on calculated sweat rates and rates of fluid ingestion was 8.8% ± 2.1% (range, 6.6%-11.7%). Measurements of the winner in the 2009 Dubai marathon revealed a BM loss of 9.8%. CONCLUSIONS: The most successful runners, during major city marathons, drink fluids ad libitum for less than approximately 60 seconds at an extrapolated fluid ingestion rate of 0.55 ± 0.34 L/h and comparable to the current American College of Sports Medicine's recommendations of 0.4-0.8 L/h. Nevertheless, these elite runners do not seem to maintain their BM within current recommended ranges of 2%-3%.

The effects of creatine and glycerol hyperhydration on running economy in well trained endurance runners.

BACKGROUND: Ingestion of creatine (Cr) and glycerol (Gly) has been reported to be an effective method in expanding water compartments within the human body, attenuating the rise in heart rate (HR) and core temperature (Tcore) during exercise in the heat. Despite these positive effects, a substantial water retention could potentially impair endurance performance through increasing body mass (BM) and consequently impacting negatively on running economy (RE). The objective of the present study was to investigate the effects of a combined Cr and Gly supplementation on thermoregulatory and cardiovascular responses and RE during running for 30 min at speed corresponding to 60% of maximal oxygen uptake (V˙O2max) in hot and cool conditions. METHODS: Cr·H2O (11.4 g), Gly (1 g·kg-1 BM) and Glucose polymer (75 g) were administered twice daily to 15 male endurance runners during a 7-day period. Exercise trials were conducted pre- and post-supplementation at 10 and 35°C and 70% relative humidity. RESULTS: BM and total body water increased by 0.90 ± 0.40 kg (P < 0.01; mean ± SD) and 0.71 ± 0.42 L (P < 0.01), respectively following supplementation. Despite the significant increase in BM, supplementation had no effect on V˙O2 and therefore RE. Both HR and Tcore were attenuated significantly after supplementation (P < 0.05, for both). Nevertheless, thermal comfort and rating of perceived exertion was not significantly different between pre- and post-supplementation. Similarly, no significant differences were found in sweat loss, serum osmolality, blood lactate and in plasma volume changes between pre- and post-supplementation. CONCLUSIONS: Combining Cr and Gly is effective in reducing thermal and cardiovascular strain during exercise in the heat without negatively impacting on RE.

Food and macronutrient intake of elite Ethiopian distance runners.

BACKGROUND: Explanations for the phenomenal success of East African distance runners include unique dietary practices. The aim of the present study was to assess the food and macronutrient intake of elite Ethiopian distance runners during a period of high intensity exercise training at altitude and prior to major competition. METHODS: The dietary intake of 10 highly-trained Ethiopian long distance runners, living and training at high altitude (approximately 2400 m above sea level) was assessed during a 7 day period of intense training prior to competition using the standard weighed intake method. Training was also assessed using an activity/training diary. RESULTS: Body mass was stable (i.e., was well maintained) over the assessment period (pre: 56.7 ± 4.3 kg vs. post: 56.6 ± 4.2 kg, P = 0.54; mean ± SD). The diet comprised of 13375 ± 1378 kJ and was high in carbohydrate (64.3 ± 2.6%, 545 ± 49 g, 9.7 ± 0.9 g/kg). Fat and protein intake was 23.3 ± 2.1% (83 ± 14 g) and 12.4 ± 0.6% (99 ± 13 g, 1.8 ± 0.2 g/kg), respectively. Fluid intake comprised mainly of water (1751 ± 583 mL), while no fluids were consumed before or during training with only modest amounts being consumed following training. CONCLUSIONS: Similar to previous studies in elite Kenyan distance runners, the diet of these elite Ethiopian distance runners met most recommendations of endurance athletes for macronutrient intake but not for fluid intake.