Previously, young people walked to school [ 4] which enabled them to achieve desirable levels of physical activity.
Most of the underlying mechanisms leading to the described desirable effects of physical activity are poorly investigated.
Most physicians recognize that regular exercise is a critical component of effective health promotion regimens, but there is substantial disagreement about details, most importantly volume: how much daily caloric expenditure, as physical activity, is desirable.
Health promotion efforts should continue efforts to encourage everyone to achieve guideline activity levels, but even modest shifts in the population distribution of physical activity are desirable.
Moreover, a standardised use of outcome measures and assessment of the intensity of physical activity are desirable and important in future randomised controlled trials to facilitate more reliable and valid synthesis of results from different studies.
Although self-report questionnaires have been shown to be prone to misinterpretation, socially desirable responses and overestimation of physical activity in adolescents [ 8], they remain commonly used at the population level because they are relatively inexpensive and easy to use [ 9].
They thought that physical activity is obviously desirable for everyone and were therefore doubtful about the necessity to prescribe it.
Parents in this study recognised the importance of physical activity for its desirable effect on their child's health or behaviour.
However, it is desirable to add questions on AS-specific physical activity.
Given the barriers to physical activity, it would be desirable if patients could gain benefit from incorporating relatively light levels of activity into their treatment modalities, which might be accomplished by simply reducing or breaking up sedentary time with movement.
