Elsevier

Diabetes & Metabolism

Volume 32, Issue 6, December 2006, Pages 617-624
Diabetes & Metabolism

Original article
Effect of Ramadan fasting on fuel oxidation during exercise in trained male rugby players

https://doi.org/10.1016/S1262-3636(07)70317-8Get rights and content

Summary

Purpose

The aim of this study was to assess the effect of Ramadan fasting on substrate oxidation in trained athletes during moderate-intensity exercise.

Methods

Nine trained men (age: 192 yr, Height: 1.780.74 m) were tested on three occasions: during a control period immediately before Ramadan (C), at the end of the first week (Beg-R), and during the fourth week of Ramadan (End-R). On each occasion, they performed submaximal cycle ergometer exercise, with work-rates that were increased progressively (loadings corresponding to 20, 30, 40, 50, 60% of Wmax). Steady-state substrate oxidation was evaluated by indirect calorimetry.

Results

Participants showed significant decreases in body mass and body fat at the end of Ramadan, relative to initial control values (P<0.001). The daily food intake was also reduced during Ramadan (P<0.01). Haemoglobin concentrations and hematocrit were significantly higher at the end-Ramadan, both at rest (P<0.001 and P<0.0001 respectively) and after exercise, (P<0.05 and P<0.01 respectively) compared to control measurements made before Ramadan. At the end of Ramadan, our subjects had increased their fat utilization during exercise. The cross-over was observed at a higher intensity at the End-R (35% vs. 30% of Wmax, P<0.001). For the same power output, the Lipox max was also higher at the End-R, compared to control value (26538 vs. 199.120 mg/min, P<0.001).

Conclusion

Ramadan fasting increases the lipid oxidation of trained athletes during submaximal exercise. The increased fat utilisation may be related to decreases in body mass and body fat content.

Résumé

Effet du jeûne du Ramadan sur l'oxydation des substrats lors de l'exercice chez l'homme entraîné

Objectif

Le but de cette étude était d'évaluer l'effet du jeûne du Ramadan sur l'oxydation des substrats lors de l'exercice modéré chez des athlètes entraînés.

Méthodes

Neuf sujets entraînés (âge: 19 2 ans, taille: 1,78 0,74 m) ont été évalués lors de trois occasions: durant une période contrôle avant le Ramadan (C), à la fin de la 1re semaine du Ramadan (Beg-R) et pendant la 4e semaine du Ramadan (End-R). A chaque visite, les sujets ont réalisé un exercice sous maximal à palier progressif sur ergocycle (charges correspondant à 20, 30, 40, 50, et 60 % de la puissance maximale). L'oxydation des substrats à l'état stable a été évaluée selon la méthode de la calorimétrie indirecte.

Résultats

Les sujets ont montré des diminutions significatives de la masse corporelle et de la masse grasse à la fin du Ramadan en comparaison avec les valeurs avant le Ramadan (P < 0,001). L'apport alimentaire journalier a été aussi réduit pendant le Ramadan (P < 0,01). Les concentrations d'hémoglobine et l'hématocrite étaient significativement plus élevés à la fin du Ramadan au repos (P < 0,001 et P < 0,0001 respectivement) et après l'exercice, en comparaison avec les valeurs avant le Ramadan (P < 0,05 et P < 0,01 respectivement). Les points de croisement métabolique (cross over) et d'oxydation maximale des lipides (Lipox max) étaient significativement plus élevés à la fin du Ramadan (+12 % et +13 % que les valeurs contrôles respectivement, P < 0,05).

Conclusion

Le jeûne du Ramadan augmente l'oxydation des lipides chez les athlètes entraînés lors de l'exercice sous maximal. L'augmentation de l'utilisation des lipides était accompagnée par des diminutions de la masse corporelle et de la masse grasse.

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