This study was designed to show the general increase in perceived exertion, perception of aches or pain in the legs, heart rate (HR), and blood lactate, and the covariance between these variables during bicycle ergometer work, and to describe individual differences both within and between power levels by testing a large group (28 male students). Estimates of perceived exertion and feelings of aches or pain in the legs were recorded using Borg's category-ratio scale (CR-10). The subjects were tested with a stepwise increase of power levels with 40 W increments up to a voluntary maximum. Though HR increases fairly linearly with power, the other variables follow positively accelerating functions with exponents of about 1.6-2 for the perceptual variables, and an exponent of about 3 for blood lactate. The results from the 8 most fit subjects could be described in the same way as for the whole group except for blood lactate, where there was a need to include a threshold value (b), that, together with a rest value (a), shows the starting point of the function (R = a + c(W - Wo)n). The data support the idea that a combination of heart rate and blood lactate is a better predictor of perceived exertion and feelings of aches and pain in the legs, than is each of the single physiological variables taken alone.

Perceptual ratings given on the Visual Analogue Scale (VAS) and the Category Ratio Scale (CR-10) were compared in 24 healthy male volunteers (18-39 years) subjected to an exercise test using a bicycle ergometer. Ratings of leg exertion were made by means of the CR-10, the VAS and, as a complementary measure, the method of free magnitude estimation (ME). Blood lactate levels (BL) and heart rates (HR) were used as correlates to sensory perception. The correlation between the CR-10 ratings and BL at 180 W were .59 (p less than .01), and between VAS ratings and BL .45 (p less than .05). The corresponding correlations with HR were .64 (p less than 0.01) and .58 (p less than 0.01), respectively. No significant correlation was found for ME. It was concluded that both the CR-10 and the VAS scales were found to be useful for the psychophysical estimation of perceptual intensities. The CR-10 scale appeared to be slightly more efficient than the VAS and both these methods much better than ME. The advantage of the CR-10 scale might be due to a greater ability to discriminate at high intensity levels.

Each of 30 male subjects judged, in a single session, the loudness of a 1000-Hz tone and the exertion perceived while pedaling a bicycle. Two psychophysical methods were used-one employing a combined category-ratio scale whose upper limit was defined as "maximum sensation" and the other a freer magnitude-estimation scale having no verbal labels. Both methods yielded data consistent with power functions, although the combined category-ratio scale gave slightly smaller exponents. The category-ratio estimates provided a measure of individual differences in perceived exertion: At any work level, the differences across subjects in judgment correlated with differences in heart rate (a physiological indicant of strain); this result is consistent with Borg's hypothesis that in dynamic work, maximal sensation is at least roughly equivalent across subjects. When the magnitude and the category-ratio estimates were converted to equivalent loudness (Stevens and Marks's method of magnitude matching), the derived loudness values also correlated with heart rate: This outcome provides evidence for the utility of the cross-modal procedure and provides further evidence consistent with Borg's model of perceived exertion.

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.

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