The effects of atropine and practolol on the perception of exertion during treadmill exercise

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Abstract
The role of heart rate (f H) in the perception of exertion (RPE) during short term progressive and prolonged (l h) exercise has been studied in healthy male subjects by observing the effects of experimentally changingf H, using intravenous injections of either atropine or practolol to modify the influence of the autonomic system. In short term exercise the results showed that independently of the large changes produced f H for a given oxygen intake, the subjects rated their exertion in accordance with the relative work performed (i.e. % [Vdot]o2max) in all experiments with and without drug administration. In prolonged exercise the association of RPE and %[Vdot]o2max was less clear. After 10min of prolonged exercise at the same [Vdot]o2 the RPE scores were lower than those observed in the progressive work tests and with atropinisalion and β-blockade RPE tended to rise during the exercise to reach a maximum value at the 60th min though [Vdot]o2 remained unchanged. It was concluded that heart rate per sehas little influence on RPE and is not an important factor underlying the perception of effort. Nor can it be used to explain the close association between RPE and relative work load found in short term exercise. During prolonged exercise more research is required before any definitive conclusion can be reached particularly bearing in mind the importance of RPE scales to the study of industrial and occupational stress.