Modelling of aerobic and anaerobic energy production in middle-distance running

Abstract

A mathematical model of performance describing aerobic and anaerobic energy production during exercise was applied to middle-distance running data from world records (WR) and from a group of elite runners (NL). The model is based on the assumption that, above a critical power (Pc), a continuous rate of anaerobic energy production occurs, until the entire anaerobic stores (W') are depleted. The fraction of metabolic power above Pc provided by anaerobic metabolism is denoted alpha. A second power threshold (Pt) sets the limit above which any further increase in power is met exclusively by anaerobic sources. The oxygen uptake kinetics was described by a monoexponential equation with time constant tau. The results show that the model successfully fits the WR over 1,500-5,000 m. However, in the range of distances from 800 to 5,000 m the performance over 800 and 1,000 m were overestimated. Contrary to Pc and the anaerobic contribution at steady state oxygen uptake, the estimate of W' was sensitive to the value assigned to tau in the range from 0 to 30 s. Using best performances from 1,500 to 5,000 m in NL resulted in Pc estimates not significantly different from the metabolic power at the lactate threshold. The anaerobic contribution at steady state oxygen uptake increased from zero at Pc to 8.3% (WR) and 7.8+/-3.1% (NL) at Pt. This suggests that a substantial contribution of anaerobic processes occurs in the range between Pc and Pt, even though the exercise does not elicit maximal aerobic power.

The critical velocity in swimming

“…Furthermore, the simplifying assumption is also made that the anaerobic contribution to the overall energy requirement is nil up to _ VO 2max ; a fact that is not always necessarily true (e.g. see Busso and Chatagnon 2006;Chatagnon and Busso 2006).…”

Modelling of aerobic and anaerobic energy production during exhaustive exercise on a cycle ergometer

“…The latter used distinct equations according to the level of power as described in the companion paper (Busso and Chatagnon 2006). In the present study, the model was used to relate the time to exhaustion to the mechanical (external) power output.…”

“…The model formulation introduced a parameter defined a which, for exercise intensities between P c and P t , is the fraction of the energy rate exceeding P c provided by anaerobic metabolism. This new formulation of the model allowed a successful fit of performance in middle-distance running (Busso and Chatagnon 2006). This study based on the computation of the metabolic power according to running velocity suggested a substantial anaerobic contribution to total energy production for power lower than P t .…”

“…This study based on the computation of the metabolic power according to running velocity suggested a substantial anaerobic contribution to total energy production for power lower than P t . The modelestimated relative anaerobic contribution was reported to increase from zero at P c until around 8% at P t (Busso and Chatagnon 2006).…”

“…In a companion paper (Busso and Chatagnon 2006), we have proposed to add other modifications in the original model. This model, which included the Wilkie's correction, assumed that the aerobic power at the steady state increases linearly with total power output until a maximal level.…”