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Comparison of fat oxidation during exercise in lean and obese pubertal boys: clinical implications
  1. G Zunquin1,2,
  2. D Theunynck1,3,
  3. B Sesboüé4,
  4. P Arhan1,
  5. D Bouglé1,5
  1. 1
    Laboratoire REcherche Littorale en Activités Corporelles et Sportives, Dunkerque, France
  2. 2
    Laboratoire de Physiologie Digestive et Nutritionnelle, CHU Caen, France
  3. 3
    Service d’anesthésie, Centre Hospitalier Dunkerque, France
  4. 4
    Service des Explorations Fonctionnelles A, CHU Caen, France
  5. 5
    Service de Pédiatrie, CH de Bayeux, France
  1. Correspondence to Dr G Zunquin, Laboratoire REcherche Littorale en Activités Corporelles et Sportives, Dunkerque, Université du Littoral Côte d’Opale, F 59140, Dunkerque, France; gautier.zunquin{at}


Objective: To examine fat oxidation rates during exercise in lean and obese pubescent children.

Design: A graded leg cycle ergometry test was performed by two groups of pubescent boys (13 lean: mean (SD) age 12.0 (0.5) years, body mass index (BMI) 18.56 (1.12) kg/m2; 17 obese: mean (SD) age 12.1 (0.1) years, BMI 26.68 (3.37) kg/m2; p<0.001). The first step of the test was fixed at 30 W and power was gradually increased by 20 W every 3.5 min. The mean ventilatory gas measurement was obtained during the last 30 s of each step for calculation of fat oxidation rate vs exercise intensity.

Results: At low intensity (0–30% of peak oxygen consumption) when fat-free mass is considered, the fat oxidation rate was identical for the two groups. At higher intensities (40%, 50% and 60% of peak oxygen consumption) the fat oxidation rate was significantly higher in lean boys than in obese boys.

Conclusion: These results confirm that obese pubertal boys have fat-free mass decreased capacities to use fat during moderate exercise. The findings suggest that obese boys need to practise physical activity at a lower intensity than healthy boys to enhance lipolysis and diminish adipose tissue and the consequences of obesity.

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  • Competing interests None.

  • Patient consent Parental consent obtained.