ISSN 0362-1197, Human Physiology, 2008, Vol. 34, No. 6, pp. 766–770. © Pleiades Publishing, Inc., 2008. Original Russian Text © E.B. Akimov, V.M. Alekseev, 2008, published in Fiziologiya Cheloveka, 2008, Vol. 34, No. 6, pp. 126–130. 766 Sufficiently intense and long exercise causes a feel- ing of exertion. Borg proposed the first scale for mea- suring this characteristic for practical purposes in 1966 [1]. In subsequent years, Borg and other researchers intensely studied both the phenomenology and the physiological and psychophysical mechanisms of sub- jective rating of perceived exertion (RPE) and devel- oped other scales and methods [1–5]. The RPE has been shown to be directly related to the exercise inten- sity, relative aerobic intensity (measured by oxygen consumption expressed in percent of the maximal oxy- gen consumption, %MOC), and heart rate (HR) in sub- jects of different ages, sexes, and degrees of training during global and regional physical exercises of various types. The RPE is an informative index of the degree of exertion in persons working at various air temperatures and other atmospheric conditions. It has been demon- strated that the RPE is a good predictor of the maximal oxygen consumption [6] and work capacity in submax- imal tests (similar to PWC 170 ) [1, 4]. The subjective RPE is used in training for orbital spaceflights [7, 8] and has been recommended for a wider range of train- ing and rehabilitation activities. Subjective criteria may be used for estimating the adequacy of training tasks to the physical capacity of an athlete’s body, the more so as exercise intensity in many sports, especially cyclic ones, has reached its limit or is approaching it. Examination of male and female elite ski racers during training has shown a significant posi- tive relationship between the RPE measured immedi- ately after training and the mean HR [9]. In many cases, however, individual pulse and subjective estimates deviate from the RPE–HR regression curve. The prac- tical implications of the existing subjective perceptual criteria and methods are likely to pertain to the overall assessment of a training session rather than to its pro- gramming. The use of subjective sensations, referred to as self- regulation, is recommended as an auxiliary means for correcting the initially set level of exertion (measured by, e.g., the HR) and/or the main way of regulating exercise intensity [2]. This requires preliminary evalu- ation (calibration) of the RPE–HR relationship [3] because the subjective estimates determined using Borg’s 6–20 scale [10] may vary in different athletes at the same HR because of individual differences in the maximum HR. We studied physiological (HR, lung ventilation (LV), and its components) and biomechanical (pedaling power, pedaling rate (PR), and ergometer flywheel resistance) responses during aerobic cycle ergometer exercises of different intensities performed on different days on the basis of the subjects' sensations alone. Production of perceived exertion (PPE) is perfor- mance of physical exercise with an intensity that causes specific sensations of the degree of exertion corre- sponding to target points of a scale or to verbal or other designations. Subjects themselves regulate the set degrees of exertion via empirical selection (setting) and control (changing) of mechanical variables, namely, the force applied to the support and/or the movement rate. For the PPE and subjective RPE, we used Alek- seev’s 50–100 scale [5], based on the numerical contin- uum of the relative working HR (%HRmax) and a uni- form distribution of verbally designated RPEs: 100, 95 (very high, VH), 90, 85 (high, H), 80, 75 (moderate, M), 70, 65 (low, L), 60, 55 (very low, VL), and 50. Twenty-seven volunteers (students of a physical education institution), including 17 men and 10 women with a mean age of 23 ±1.6 years, body weight of 70 ± 12 kg, and height of 171 ± 7 cm performed exercise on a Monark 828E cycle ergometer. On the first day, the exercise intensity was increased at a step of 40 W (3 min at every step) until failure, i.e., inability to con- SHORT COMMUNICATIONS Effects of the Production of Perceived Exertion during Cycle Ergometry E. B. Akimov and V. M. Alekseev Russian State University of Physical Education, Sports, and Tourism, Moscow, Russia Received May 21, 2008 Abstract—Physiological and biomechanical effects of aerobic exercise varying in intensity were studied on the basis of the subjects' perceived exertion. It was demonstrated that exercise regulated with the use of a 50–100 rating scale was characterized by reliably stable heart-rate and respiratory reactions and biomechanical responses. The relative working heart rate (HR) expressed in percent of the individual HRmax was found to be closely correlated with the values on the 50–100 scale within a wide range during exercise with constant or increasing perceived exertion. DOI: 10.1134/S0362119708060169