Twenty five studies (n=approximately 8,660) were included in the review, but only nine studies were included in the meta analysis. Seven RCTs were rated as high methodological quality, six as good and 12 as fair. Methodological limitations included differences at baseline between groups, high attrition rates and inadequate reporting of outcomes.
Long-term effectiveness of physical activity interventions: Four RCTs reported increases in weekly energy expenditure of up to 975kcal and physical fitness of up to 11% for intervention groups compared to no-intervention and minimal-intervention control groups. The proportion of participants in the physical activity intervention group who met recommended targets or adhered to physical activity prescriptions ranged between 4.5% and 81%.
One RCT found significant increases in the proportion of participants who met recommended physical activity targets in the physical activity group compared to no intervention group (OR 3.31, 95% CI 1.99 to 5.52). No statistically significant differences were reported between physical activity groups compared to minimal intervention control (two RCTs) or health-care staff advice (two RCTs). There was evidence of significant increases in self-reported energy expenditure for physical activity groups compared to no intervention control (SMD 0.24, 95% CI 0.12 to 0.37; two RCTs). There were no statistically significant differences between a physical activity group and a no-intervention control group for number of minutes per week of physical activity (one RCT). There were significant increases in physical fitness in the physical activity intervention groups compared to the physician advice control groups (SMD 0.15, 95% CI 0.06 to 0.24; three RCTs) and for minutes per week of physical activity intervention groups compared to the minimal control groups (SMD 0.13, 95% CI 0.01 to 0.24; one RCT), but no statistically significant differences between physical activity interventions and minimal control group for physical fitness (two RCTs).
There was evidence of statistical heterogeneity for the analyses that compared physical activity intervention groups with minimal intervention control for physical fitness (I2=97.7%). There was no evidence of statistical heterogeneity for any other analysis. No differences were reported to results after sensitivity analyses. Mixed results were reported for sustainability of intervention effects up to 24 months. Results for the effectiveness of intervention-specific populations were also reported.
Effectiveness of specific intervention components: No significant differences were reported between groups for initial intervention intensity (two RCTs). Mixed results were reported for written exercise prescriptions as part of a physical activity intervention compared to control groups. Mixed results were also reported for tailored versus standard intervention messages; one RCT found evidence of effectiveness of culturally tailored strategies.