The physical demands of stage race cycling are well documented. However, less is known about the physiological demands placed on the body in terms of fluid balance and thermoregulation. Recent investigations in hot and or humid conditions have observed body mass deficits of ~ 2kg (2.8%) per stage during an international stage-race tour (2) despite meeting nutritional guidelines for fluid and carbohydrate intake (1). However, the physiological impact of stage-race cycling in a thermoneutral environment has not been established. The purpose of this study was to quantify the fluid and food intake during a men`s National Road Series stage-race in thermoneutral conditions and observe the changes in body mass, thermal comfort and gastrointestinal temperature (TGI). The information from this study will help to determine how periods of intense cycling in cool conditions impact thermoregulation and cycling performance. Methods Five men (age: 19.6 ± 0.4 y, body mass: 72.4 ± 5.0 kg, and height 179 ± 3 cm) of the Australian Institute of Sport Road Cycling squad participated in the study. The cyclists competed in the Tour of Gippsland (Victoria, Australia) consisting of 9 stages (55 ± 21 km; 71 sprints; 20 hill climbs) over 4.5 d in July/August. On days 1-4, a `first waking` urine sample was analysed for determination of specific gravity (USG). Body mass (BM) and thermal comfort was recorded immediately before and after each stage. Power output via an SRM power meter (Jülich, Germany) and TGI via an ingestible pill (CorTemp; HQInc, Palmetto, Florida, USA) was recorded throughout each stage. Cyclists recalled the types and volumes of fluid and food consumed throughout each stage. All data presented are mean ± SD. Results Stage-race characteristics can be found in Table 1. Cyclists performance was reflected with overall general classification ranging from 1st - 97th placing, including 5 stage wins, overall Criterium and Young Rider classification Cyclists presented in the morning on race day with USG readings of 1.023 ± 0.006. Mean fluid losses were 1.1 ± 0.3 L.h-1 (Fig 1a; range = -0.6 to -2.0 L.h- 1). Mean change in body mass was -1.3 ± 0.5% (range -0.5 to -2.7%; Fig 1b) which was matched with peak TGI of 38.9 ± 0.7°C (67% of observations made were >39.0°C; Fig 1c). Subjective ratings of thermal comfort were 4.7 ± 0.5 (where a score of 5 = "warm"). Cyclists consumed 510 ± 450 ml during each stage (0.32 ± 0.25 L.h-1), which consisited of either water or sports drink which correlated with stage distance (R2 = 0.95). Mean carbohydrate intake was 48 ± 45 g which is equal to 28 ± 26 g.h-1 and ~0.64 g.kg-1 BM. Discussion/Conclusion This study captured novel and insightful data which details the effects of highintensity stage-race cycling in cool conditions. We were surprised to find consistent observations of high peak TGI coupled with moderate changes in body mass despite adequate opportunity for food and fluid consumption and the expected cooling effect of airflow during each stage. These data provide evidence of increased thermal strain which may compromise cycling performance in low ambient conditions. Further research is required to determine optimal preparation strategies for cyclists competing in cool temperatures, including the next scheduled World Championships (Geelong, Australia in 2010) and Olympic Games (London, England in 2012).
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