C-20: Thematic Poster – Weight and Athletes: THURSDAY, JUNE 2, 2005 9:00 AM - 12:00 PM: ROOM: Ryman C1: 9:00 to 10:00 a.m., View Presentations – 10:00 a.m. to 12:00 p.m., Chair Leads Discussion
A previous study found elite Kenyan athletes to be in negative energy balance prior to major competition (Onywera et al. Int J Sports Nutr. In press). In that study, estimated energy intake (EI) over the 7 day assessment period was significantly lower than energy expenditure (EE) as assessed using Physical Activity Ratio (EI: 12.5 ± 1.2 MJ·d1 vs. EE: 15.1 ± 0.5 MJ·d−1 (mean ± SD); P <0.001) and this was accompanied by a significant reduction in body mass (BM:58.9 ± 2.7 kg vs. 58.3 ± 2.6 kg; P <0.001).
To confirm the above findings using the Doubly Labeled Water (DLW) method of assessing EE.
Nine elite Kenyan endurance runners based at a high altitude training camp in the Rift Valley (altitude:2200 m a.s.l, daytime ambient temperature: 10–26°C) were recruited to participate in this study one week before the Kenyan 2004 Olympic trials. EI was assessed using a 7 day nutritional diary, whilst EE was estimated by DLW.
The reported EI of 13.2 ± 1.3 MJ·d−1 was significantly lower than EE (14.6 ± 1.0 MJ·d−1; P =0.049). Calculation of underreporting (underreporting = [(EI - EE)/EE] * 100%) and undereating (undereating = [(ΔBM * 30 MJ/7 d)/EE] * 100%) revealed (median (range)) 8.9 (−13 (−23.6 -8.8)) %underreporting and 9.4 (−8.6 (−54.8 - 38.7)) %undereating, respectively. Total water intake (i.e. reported water intake plus calculated metabolic water) was lower than water loss (4.0 ± 0.7 L·d−1 vs. 4.5 ± 0.8 L·d−1; P = 0.02); an amount that can be accounted for by inspired atmospheric moisture (typically 3–10 % of water turnover at 40 % relative humidity at 22°C, Schoeller and van Santen. J Appl Physiol 53: 955–9, 1982). There was no significant change in BM over the training period (56.0 ± 3.4 kg vs. 55.7 ± 3.6 kg; P = 0.285). The diet consisted mainly of carbohydrate sources (67.3 ± 7.8%, 9.8g·kg−1 BM·d−1) compared with protein (15.3 ± 4.0%, 2.2 g·kg−1 BM·d−1) and fat (17.4 ± 3.9%).
These results confirm previous observations that elite Kenyan endurance runners are in negative energy balance prior to major competition. The significance of this remains to be determined.
Supported in part by Global Sports Communication, The Netherlands.