Blood lactate response to the Canadian Aerobic Fitness Test (CAFT)

This study evaluated the blood lactate (LA) response to stepping exercise, specifically the Canadian Aerobic Fitness Test (CAFT). It also compared the correlation between either LA or heart rate (HR) at a given stage of the CAFT and directly measured maximal aerobic power (VO2max). A total of 137 male Canadian Forces (CF) personnel between the ages of 18 and 53 years participated in this study. The LA concentration after each stage of the CAFT was measured in all subjects from blood sampled from the fingertip. Seventy-eight of these subjects also had their VO2max measured directly during a maximal treadmill run. The results showed that increasing stages of the CAFT were associated with exponentially increasing LA. At Stage 5, LA concentration ranged from 1.0 to 7.0, with a mean of 2.6 mmol.L-1, while HR ranged from 72 to 192 with a mean of 132 beats. When the LA and HR measures at Stage 5 of the CAFT were compared for their ability to predict VO2max, the correlation between lactate and VO2max was -0.71 (p less than .001); between HR and VO2max it was -0.36 (p less than .01). These results suggest that LA is a better predictor of VO2max than HR.