A new aerobic fitness score based on lactate sensing during sub-maximal exercise.

Given the known clinical utility of cardiorespiratory fitness, measurement of physiological responses to submaximal exercise may be a feasible approach well suited for diagnostic and prognostic purposes in non-athletes and the chronically ill. Lactate levels and watt output during a short submaximal exercise and a subsequent relaxation period yield an aerobic score that is consistent with cardiorespiratory fitness grades in non-athletes and that may be used as a marker in such approaches. In this study, 28 females (23 +/- 3 years) were submitted to a 15 min submaximal recumbent bike session, and their capillary and saliva lactate concentrations were recorded and plotted against time. An individual aerobic score was calculated from this curve, using watt output during equal relative percentiles of maximum heart-rate benchmarks. The scores were compared with respective results in a VO2max test and with a similar scoring system in 14 older (51 +/- 9 years) females; they correlated with the 6 categories of the VO2max test results and classified into 3 categories of VO2max grades (very poor/poor; fair/good; excellent/superior) with a combined accuracy of 80.95%. More studies are required to validate the potential utility of this submaximal test as an additional risk factor for diagnostic purposes in non-athletes.