Question naires were the more predominant way to evaluate PA .
Most studies showed that PA promotes a protective effect against a higher BF gain .
CONCLUSION It was concluded that PA has a protective effect against BF with differences between the genders and according to the BF marker or measurement assessed ; higher intensity PA leads to a greater effect against BF gain in both genders ; and the maintenance or increase of PA level on BF observed through analysis of change in PA level yielded more consistent findings in the relation between PA and BF
BACKGROUND Physical activity ( PA ) practice has been inversely associated to body  fat ( BF ) and recommended as a way to reduce and prevent obesity .
The objective of this study was to conduct a systematic review on the association of  PA and BF in adolescence .
BMI-related errors in the measurement of obesity
Body mass index ( BMI ) has various deficiencies as a measure of obesity , especially when the BMI measure is based on self-reported height and weight . BMI is an indirect measure of body fat compared with more direct approaches such as bioelectrical impedance . Moreover , BMI does not necessarily reflect the changes that occur with age . The proportion of body fat increases with age , whereas muscle mass decreases , but corresponding changes in height , weight and BMI may not reflect changes in body fat and muscle mass . Both the sensitivity and specificity of BMI have been shown to be poor . Additionally , the relation between BMI and percentage of body fat is not linear and differs for men and women . The consequences of the errors in the measurement of obesity with BMI depend on whether they are differential or nondifferential . Differential misclassification , a potentially greater problem in case – control and cross-sectional studies than in prospect i ve cohort studies , can produce a bias toward or away from the null . Nondifferential misclassification produces a bias toward the null for a dichotomous exposure ; for measures of exposure that are not dichotomous , the bias may be away from the null . In short , the use of BMI as a measure of obesity can introduce misclassification problems that may result in important bias in estimating the effects related to obesity
Question naires were the more predominant way to evaluate PA .
Most studies showed that PA promotes a protective effect against a higher BF gain .
CONCLUSION It was concluded that PA has a protective effect against BF with differences between the genders and according to the BF marker or measurement assessed ; higher intensity PA leads to a greater effect against BF gain in both genders ; and the maintenance or increase of PA level on BF observed through analysis of change in PA level yielded more consistent findings in the relation between PA and BF
BACKGROUND Physical activity ( PA ) practice has been inversely associated to body  fat ( BF ) and recommended as a way to reduce and prevent obesity .
The objective of this study was to conduct a systematic review on the association of  PA and BF in adolescence .