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Anaerobic threshold in patients with chronic cardiac failure due to ischaemic heart disease
J S Elborn1, M Riley, C F Stanford
1Royal Victoria Hospital, Belfast, Northern Ireland.
Objectives:
Anaerobic threshold was measured to examine its relationship with venous lactate levels and the reproducibility of gas exchange methods.
Methods:
Twenty patients with chronic cardiac failure due to ischaemic heart disease underwent two successive treadmill tests with measurements of respiratory gas exchange.
Results:
An anaerobic threshold was demonstrated in 78 p. 100 of tests, by plotting either VE/VO2 or VCO2/VO2, and reproducibility between the two tests was satisfactory. Peripheral venous lactate levels did not increase from rest to the end of the exercise stage prior to the anaerobic threshold, but did increase significantly thereafter. Where an anaerobic threshold could be demonstrated, it was reproducible and correlated strongly with peak achieved VO2.
Conclusion:
However, as measurement of anaerobic threshold requires exercise to 90 p. 100 maximum VO2, it may be preferable to continue until limiting symptoms, and use peak achieved VO2 as the end point. Anaerobic threshold is a reproducible measure of anaerobic exercise capacity.