How one feels about exertion moderates the response to exercise and effort. Thus, the perception of what is happening in exercise, and its concomitant effect on physiological function, needs to be known to further understand the nature of an exercise response. How one feels modifies reactions to exercise stress and the mechanisms that underlie them. Among many of today's sport scientists, there is an opinion that physical strain does not involve any psychological factors. This is a false stance.
Exercise is never a purely mechanistic physiological reaction.
The interpretation of the exercise experience governs the nature, quality, and extent of the exercise response. To fully understand and accurately assess the nature of an exercise behavior, it is necessary to measure as many moderating variables as possible. Physiological measures can be used to grade the strain for each individual, but so can exertion estimates. Without knowledge of the psychological moderator variables, the physiological measure alone would be misleading. Its value as a predictor variable usually would be negligible.