A Cochrane review included 20 studies with a total of 5 870 subjects. The studies varied in the timing and intensity of the smoking cessation and exercise programmes. The largest study was an internet trial with 2 318 participants, and eight of the studies had fewer than 30 people in each treatment arm. Four studies showed significantly higher abstinence rates in a physically active group versus a control group at end of treatment. One of these studies also showed a significant benefit for exercise versus control on abstinence at the three-month follow up and a benefit for exercise of borderline significance (P = 0.05) at the 12-month follow up. Another study reported significantly higher abstinence rates at six month follow-up for a combined exercise and smoking cessation programme compared with brief smoking cessation advice. One study showed significantly higher abstinence rates for the exercise group versus a control group at the three-month follow up but not at the end of treatment or 12-month follow up. The other studies showed no significant effect for exercise on abstinence.
Comment: The quality of evidence is downgraded by study quality (19 studies were rated at unclear risk in at least one domain) and by inconsistency (unexplained variability in results and heterogeneity in interventions and outcomes).