Flynn, M. G., Costill, D. L., Kirwan, J. P., Mitchell, J. B., Houmard, J. A., Fink, W. J., Beltz, J. D., & D'Acquisto, L. J. (1990). Fat storage in athletes: Metabolic and hormonal responses to swimming and running. International Journal of Sports Medicine, 11, 433-440.

Male swimmers (N = 8), runners (N = 8), and triathletes (N = 6) were tested in running and swimming at similar intensities. The triathletes performed both running and swimming tests at 70% VO2max intensity. Blood samples were collected before and at 15, 30, 60, and 120 minutes after exercise. Expired gases and heart rates were obtained during exercise and recovery.

The caloric costs of recovery to both activities were similar but the RERs suggested increased fat oxidation during recovery from swimming. This may have been caused by depleted hepatic glycogen reserves. Recovery blood glucose levels were substantially lower for swimmers than runners suggesting that swimmers use more CHO rather than fats to perform similar amounts of work.

Implication. Swimming is not as good a "fat-burning" activity as is running. The dynamics of energy use and restoration are not sufficient to explain why swimmers display greater body fat measures than runners.

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