Sixteen studies (7,465 participants recruited) were included: 13 RCTs (6,306 patients recruited), 2 non-randomised controlled trials (549 patients recruited) and one uncontrolled before-and-after study (610 patients recruited).
There was substantial heterogeneity in the programmes reviewed in terms of the intervention design, recruitment methods, participants recruited, outcome measures, length of follow-up, and results; this made comparison difficult. Losses to follow-up were often high, ranging from 3 to 61%.
In the short term (less than 6 months), most studies (11 out of 15) reported some significant benefit of TTM-based interventions over control conditions, in terms of either stage progression or activity levels. Only 6 studies showed a statistically-significant benefit in terms of increased activity. In one study, the control group (who were given 6 months' free gym membership, starting with 3 weeks of supervised exercise instruction) showed a statistically-significant increase in activity levels in comparison with TTM interventions. In the longer term (over 6 months), only 2 out of 7 studies reported some benefit of TTM- based programmes.