Reference:
Pavey TG, Taylor AH, Fox KR, Hillsdon M, Anokye N, Campbell JL, Foster C, Green C, Moxham T, Mutrie N, Searle J, Trueman P, Taylor RS. Effect of exercise referral schemes in primary care on physical activity and improving health outcomes: systematic review and meta-analysis. British Medical Journal 2011;343: d6462.