The heterogeneity in reported effects was reduced in higher quality studies , when physical activity was self-directed with some professional guidance and when there was on-going professional support .
Our review suggests that physical activity interventions have a moderate effect on self reported physical activity and cardio-respiratory fitness , but not on achieving a predetermined level of physical activity .
Due to the clinical and statistical heterogeneity of the studies , only limited conclusions can be drawn about the effectiveness of individual components of the interventions .
BACKGROUND Little is known about the effectiveness of strategies to enable people to achieve an increase in their physical activity .
OBJECTIVES To assess the effects of interventions for promoting physical activity in adults aged 16 years and older , not living in an institution .
The effect of life events and exercise program format on the adoption and maintenance of exercise behavior.
This study prospect ively investigated the effects of major life events on subsequent  exercise adherence rates of individuals ( N = 173 ) participating in a 2-year , r and omized , controlled clinical trial of 3 different exercise conditions ( higher-intensity home-based ; lower-intensity home-based ; and higher-intensity class-based ) . For 3 of 4 6-month exercise-adherence periods , an analysis of variance indicated a significant main effect ( p < .05 ) for major life events . Compared with participants reporting 0 or 1 major life event ,  exercise adherence in the maintenance phase was significantly lower for those reporting 3 or 4 major life events regardless of the exercise condition . No significant life-event-exercise-adherence relationship was found in the adoption phase of exercise participation ( i.e. , Months 1 to 6 ) . The deleterious effect of life events emphasizes the importance of instruction regarding how to prepare for high-risk situations that can lead to missed exercise sessions or to program attrition
The heterogeneity in reported effects was reduced in higher quality studies , when physical activity was self-directed with some professional guidance and when there was on-going professional support .
Our review suggests that physical activity interventions have a moderate effect on self reported physical activity and cardio-respiratory fitness , but not on achieving a predetermined level of physical activity .
Due to the clinical and statistical heterogeneity of the studies , only limited conclusions can be drawn about the effectiveness of individual components of the interventions .
BACKGROUND Little is known about the effectiveness of strategies to enable people to achieve an increase in their physical activity .
OBJECTIVES To assess the effects of interventions for promoting physical activity in adults aged 16 years and older , not living in an institution .