Many indicators of over-reaching and over-training have been proposed, using both physiological and psychological techniques. Field testing of athletes has led us to believe that a decrease in the ratio of blood lactate concentration to ratings of perceived exertion indicates a fatigued and/or over-reached state following intensive training. The purpose of this study, therefore, was to test the hypothesis that a decrease in the ratio of blood lactate concentration to ratings of perceived exertion would indicate an over-reached state. Seven well-trained male cyclists performed two weeks each of: normal (moderate) training, overtraining and recovery. During each time period an incremental exercise test was performed to maximal effort with blood lactate concentration (HLa) and ratings of perceived exertion (RPE) obtained for each workload. All seven subjects became over-reached during the two week period of intensive interval training. The ratio of HLa:RPE (multiplied by 100) decreased with all workloads following both one (mean decrease 29.1 +/- 3.0%) and two (mean decrease 48.7 +/- 2.5%) weeks of overtraining. However, only the decrease at the maximal workload was statistically significant. Examining the individual data revealed that at maximal workload all seven subjects had HLa:RPE ratios of less than 100 when over-reached. The ease and speed at which the HLa:RPE ratio can be determined may make it useful for coaches and athletes in monitoring intensive exercise training and recovery.