Lewis BA, Williams DM, Frayeh A, Marcus BH Self-efficacy versus perceived enjoyment as predictors of physical activity behaviour. Psychol Health. 2016;31(4):456-69. doi: 10.1080/08870446.2015.1111372. Epub 2015 Nov 18.
McAuley E, Duncan T, Tammen VV Psychometric properties of the Intrinsic Motivation Inventory in a competitive sport setting: a confirmatory factor analysis. Res Q Exerc Sport. 1989 Mar;60(1):48-58.
Omorou AY, Langlois J, Lecomte E, Briançon S, Vuillemin A Cumulative and bidirectional association of physical activity and sedentary behaviour with health-related quality of life in adolescents. Qual Life Res. 2016 May;25(5):1169-78. doi: 10.1007/s11136-015-1172-7. Epub 2015 Nov 6.
Williams NH, Hendry M, France B, Lewis R, Wilkinson C Effectiveness of exercise-referral schemes to promote physical activity in adults: systematic review. Br J Gen Pract. 2007 Dec;57(545):979-86. doi: 10.3399/096016407782604866. Review.
Comparative Study in Long-term Commitment to Physical Activity After Two Different Resumption Programs
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.
