THE EFFECTS OF BLOOD LACTATE CONCENTRATION ON PERCEPTION OF EFFORT DURING EXERCISE 424

Abstract

Several studies have reported that rating of perceived exertion (RPE) covaries more with blood lactate concentration (BLC) than other measures of relative exercise intensity. However, few have studied the relationship between RPE and BLC across a variety of graded exercise tests (GXTs) and exercise training settings. The purpose of this study was to determine if RPEs are reliable at matched BLC between the GXT and steady state exercise in the field setting. Thirteen healthy males (25±5.3 yrs) completed two maximal treadmill protocols (Bruce and Balke) and one steady state exercise trial on a treadmill at two intensities which lasted approximately 7 minutes each. The intensities (40% & 70% VO2 max) were below and above their ventilatory threshold. RPEs were recorded during the last 2 minutes and last minute of each stage of the Bruce and Balke protocols, respectively, and the last minute of each workload of the field trial (FT). Blood samples were collected for BLC analysis every minute during the GXTs and immediately following the end of each workload of the FT. RPEs were cross compared between the FT and the GXTs at matched BLCs measured from the FT, using a repeated measures ANOVA across exercise trials. Table There were no significant differences in RPEs at matched BLCs between the FT and GXTs at the lower intensity; however, at the higher intensity, RPEs were significantly lower during the FT compared to the GXTs. These results suggest that the relationship between RPE and BLC established during GXT may not be transferable to the exercise training setting at exercise intensities in the typical prescription range of 50-85%. Therefore, using RPE for exercise prescription may not be an effective method for regulating exercise intensity according to BLC.