Prolonged exercise at a constant load on a bicycle ergometer: ratings of perceived exertion and leg aches and pain as well as measurements of blood lactate accumulation and heart rate.

To study changes over time during prolonged exercise on a bicycle ergometer at a constant load, 22 healthy males rated perceived exertion as well as aches and pain in the legs, and measurements were taken on blood lactate accumulation and heart rate (HR). The prolonged exercise was carried out at WOBLA (the power level eliciting a blood lactate concentration of 4 mmol X l-1). All four measured variables, ratings of perceived exertion, ratings of aches and pain in the legs, blood lactate accumulation, and HR, grew systematically according to negatively accelerating functions. HR showed more of a steady state, whereas all the other three variables grew continuously over time. Three subgroups were identified related to the blood lactate response after 15 min at WOBLA: elevated (greater than 5 mmol X l-1), intermediate (3.5-4.9 mmol X l-1), and low (less than 3.4 mmol X l-1). It was suggested that a major contribution to the discrepancies in blood lactate between the subgroups after 15 min was partly due to insufficient warming up, which was 5 min at 20 W as compared with the final power level (WOBLA), which differed between 140 and 260 W. After 15 min both rated perceived exertion and rated aches and pain in the legs were related to the corresponding blood lactates. It was suggested that rated perceived exertion and rated aches and pain in the legs partly reflected the degree of "anaerobic" metabolism measured as blood lactate.