Abstract
In a recent article in the Consultant’s Corner section of this journal, Bennett (1988) considers a problem in the area of kinesiology. Apparently, when humans exercise strenuously, an ‘anaerobic threshold’ is passed; this threshold is defined to be the level of oxygen consumption ‘just below that at which an abrupt change in metabolism occurs accompanied by associated changes in the exchange of gases in the lungs’. This is thought to be reflected in the relationship of expired ventilation ($y$) to oxygen uptake ($x$). For the particular data set, pertaining to a single individual taking part in one particular test, given in Table 1 of Bennett (1988), we can see no evidence of any sudden change of the kind expected. While we are not qualified to doubt the existence of the anaerobic threshold in general, we feel we must point out that it appears that either (a) an abrupt change in metabolic activity does not necessarily translate directly to a similar change in expired ventilation, or (b) at least for some individuals, the physiological changes take place more gradually.