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 .
Good maintenance of high-impact activity-induced bone gain by voluntary, unsupervised exercises: An 8-month follow-up of a randomized controlled trial.
The purpose of this study was to evaluate whether premenopausal women 's voluntary unsupervised aerobic and step training could maintain the skeletal benefits obtained by an 18-month supervised high-impact training , and if so , to what extent . Thirty women of the original 39 study subjects ( i. e. , persons who completed the preceding 18-month r and omized training intervention and who volunteered to continue the training on their own for a further 8 months ) and 19 women of the 45 original control subjects ( i.e. , persons who volunteered to continue as controls ) were included . The study group trained an average of twice per week and the training consisted of regular aerobic and step classes provided by local fitness centers .  Areal bone mineral density ( BMD , g/cm2 ) was measured from the lumbar spine , femoral neck , trochanter area of the femur , distal femur , patella , proximal tibia , calcaneus , and dominant distal radius at baseline and after 18 and 26 months . During the extended 8-month follow-up , the BMD of the study group increased more at the femoral neck ( the intergroup change was + 0.9 % at 18 months and + 2.8 % at 26 months , p = 0.004 for the change between 18 and 26 months ) and remained at the 18-month level at the distal femur , patella , proximal tibia , and calcaneus . In these sites , the statistically significant changes during the entire 26 months of training were 1.7 - 4.0 % in the training group as compared with the changes of -0.9 - 1.5 % in the control group . In the lumbar spine , BMD decreased from the 18-month level in both groups . In conclusion , the significant BMD increases that were obtained by supervised 18-month high-impact training were effectively maintained with subsequent unsupervised regular aerobic and step classes ( twice per week ) . The finding emphasizes the effectiveness and feasibility of self-controlled aerobic and step exercises in the primary prevention of osteoporosis among healthy premenopausal women
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 .