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 .
Randomised, controlled walking trials in postmenopausal women: the minimum dose to improve aerobic fitness?
Background : The American College of Sports Medicine recommends 20–60 minutes of aerobic exercise three to five days a week at an intensity of 40/50–85 % of maximal aerobic power ( Vo2max ) reserve , expending a total of 700–2000 kcal ( 2.93–8.36 MJ ) a week to improve aerobic power and body composition . Objective : To ascertain the minimum effective dose of exercise . Methods : Voluntary , healthy , non-obese , sedentary , postmenopausal women ( n = 121 ) , 48–63 years of age , were r and omised to four low dose walking groups or a control group ; 116 subjects completed the study . The exercise groups walked five days a week for 24 weeks with the following intensity ( % of Vo2max ) and energy expenditure ( kcal/week ) : group W1 , 55%/1500 kcal ; group W2 , 45%/1500 kcal ; group W3 , 55%/1000 kcal ; group W4 , 45%/1000 kcal .  Vo2max  was measured in a direct maximal treadmill test .  Submaximal aerobic fitness was estimated as heart rates at submaximal work levels corresponding to 65 % and 75 % of the baseline Vo2max . The body mass index ( BMI ) was calculated and percentage of body fat ( F% ) estimated from skinfolds . Results : The net change ( the differences between changes in each exercise group and the control group ) in Vo2max was 2.9 ml/min/kg ( 95 % confidence interval ( CI ) 1.5 to 4.2 ) in group W1 , 2.6 ml/min/kg ( 95 % CI 1.3 to 4.0 ) in group W2 , 2.4 ml/min/kg ( 95 % CI 0.9 to 3.8 ) in group W3 , and 2.2 ml/min/kg ( 95 % CI 0.8 to 3.5 ) in group W4 . The heart rates in st and ard submaximal work decreased 4 to 8 beats/min in all the groups . There was no change in BMI , but the F% decreased by about 1 % unit in all the groups . Conclusions : Walking ( for 24 weeks ) at moderate intensity 45 % to 55 % of Vo2max , with a total weekly energy expenditure of 1000–1500 kcal , improves Vo2max and body composition of previously sedentary , non-obese , postmenopausal women . This dose of exercise apparently approaches the minimum effective dose
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 .