Scaling behaviour of in athletes and untrained individuals

Abstract

Objective: The present study analysed the allometric relationship (MR = a · M^b) between human metabolic rate (MR), ranging from resting to maximal metabolic conditions, and body mass (M ), both in athletes of different specialization and untrained individuals.

Subjects and methods: Two hundred and seventy male athletes and 43 untrained men performed a continuous incremental test to volitional exhaustion on a motorized treadmill. Metabolic rate (i.e. ) was measured during resting (), sub-maximal (walking at 5 km h⁻¹ ; running at 7.5 km h⁻¹ ; ventilatory anaerobic threshold ) and maximal exercise conditions (maximum oxygen uptake ).

Results: A significant difference ( p < 0.001) in the MR–body mass relationships between athletes and controls was found. For the control group, the mass exponent b exhibited a non-significant ( p = 0.37) increase with increasing metabolic demand (b = 0.69, 0.76, 0.76, 0.84, and 0.89, for , , , , and , respectively). In contrast, the corresponding mass exponent for the athletic group significantly ( p < 0.01) decreased when moving from resting to maximal metabolic conditions (b = 0.98, 0.88, 0.80, 0.69, and 0.67).

Conclusion: These results indicate that the recently proposed allometric cascade model may be valid in describing the scaling behaviour of MR in untrained individuals, but not in athletes of different specialization.

• Metabolic scaling
• resting metabolic rate
• maximal oxygen uptake
• exercise
• metabolism
• body size