Differences in self-reported perceived and objective measures of duration and intensity of physical activity for adults in skiing.

The effect of physical activity (PA) on health is well documented. The assessment of PA is a valuable and important issue, however, there are several methodological issues among the available methods of measurement that may have implications for the prevention of specific diseases. The purpose of this study was to examine the differences between an objective method of measurement and the subjective estimation of the PA for novice skiers. Seventy-five students aged 19-21 years old with no previous experience in ski participated in this study. Participants wore a heart rate monitor during practice in order to record the exercise intensity. Simultaneously, a trained observer recorded their time on task. A day after the objective measurement, the participants filled a questionnaire in order to estimate their perceived exertion during practice as well as their perceived time on task. The results showed (1) differences between the observed time on task and the perceived recalled time, (2) no differences overall between the recorded and perceived recalled intensity of exercise but when groups were split according to their objective intensity a difference was found for each group respectively. Participants overall had overestimated the time on task, but they had underestimated the intensity of their effort recalled 1 day after their practice. These results raise the question whether a questionnaire as method of measuring PA is reliable, especially when it is used to estimate energy expenditure. However, further studies must be made in order to examine the implications of such a question.