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Int J Sports Med 1989; 10: S41-S48
DOI: 10.1055/s-2007-1024953
© Georg Thieme Verlag Stuttgart · New York

Eating, Drinking, and Cycling. A Controlled Tour de France Simulation Study, Part 2: Effect of Diet Manipulation*

F. Brouns, W. H. M. Saris, J. Stroecken, E. Beckers, R. Thijssen, N. J. Rehrer, F. ten Hoor
  • Nutrition Research Centre, Department of Human Biology, University of Limburg, Maastricht, the Netherlands
* Supported by a grant from Wander Ltd., Bern, Switzerland
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Publication Date:
14 March 2008 (online)

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Eating, Drinking, and Cycling. A Controlled Tour de France Simulation Study, Part 1*Int J Sports Med 1989; 10(S 1): S32-S40
DOI: 10.1055/s-2007-1024952

Abstract

Field studies during the Tour de France indicated that cyclists consume 30% of daily energy intake as liquid carbohydrate (CHO)-enriched nutrition with the goal of maintaining energy and CHO balance. The aim of the present investigation was to study the effect of such dietary manipulation during 2 days of long-lasting exhausting cycling on food and fluid intake, energy balance, nitrogen balance, and nutrient oxidation.

Thirteen highly trained cyclists were divided into two subgroups receiving ad libitum either a primarily maltodextrin-based beverage (Mf) (20% w/v, 85% maltodextrin, 15% fructose) or a 50/50% composed fructosemaltodextrin (FM) beverage in addition to their normal diet. The study was performed during a 7-day stay in a respiration chamber (2 preparation days, 1 standardized resting day, 2 cycling days, 1.5 standardized recovery days), allowing for continuous gas analysis, weighed food and fluid intake procedure, and collection of excretes. The data of this study were compared with data from the same subjects receiving a normal CHO-rich diet (N) (60 En%) in a separate experiment.

The results showed that the cyclists receiving Mf were able to maintain EB during sustained exercise days in contrast to when receiving N and to subjects receiving FM. With Mf treatment CHO intake increased, up to 80 En% (17.5 ± 1.0 g · kg-1 BW) and carbohydrate balance remained positive. The subjects receiving FM had the largest CHO oxidation, calculated from R. Protein oxidation significantly increased in N and FM as a result of exercise but not in Mf. The latter subjects were in slighly negative nitrogen balance at a protein intake level of 1.4 g · kg-1 BW.

The results show that supplementation with maltodextrin beverages is an adequate measure to maintain EB and CHO balance and furthermore that increased CHO intake induces protein sparing. The protein requirement while being in energy and carbohydrate balance during days of sustained exhausting cycling was in the range of 1.5-1.8 g · kg-1 BW.

Key words

Food intake - fluid intake - diet manipulation - energy balance - nitrogen balance - nutrient oxidation - cycling

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