Background This paper describes the protocol and methodological prerequisites for a randomised controlled exercise intervention. Selected baseline data from the study are also presented, demonstrating some methodological challenges related to exercise intervention trials. The aim of the trial was to study the effects of exercise training on physiological responses to acute psychosocial stress in untrained individuals.
Methods Individuals with a low level of physical activity were invited to participate in an exercise intervention lasting for 6 months. A total of 119 participants were included and went through a peak oxygen uptake test and a psychosocial stress test at baseline. Adrenocorticotropic hormone (ACTH) and cortisol were measured in connection to the stress test to identify the physiological response.
Results Almost 90% of the participants reported themselves as untrained, but results from the objectively measured oxygen uptake did not seem to correspond to the reported sedentary lifestyle. The primary outcome measures at baseline varied between individuals. The mean change from pre-test to peak value was 214% for ACTH and 94% for cortisol. Of these, 13 individuals did not respond in ACTH and/or and cortisol.
Discussion Supposedly untrained individuals seeking participation in an exercise intervention might not be as untrained as they report, a methodological consideration of importance when evaluating the effects of training. Another important consideration is related to the primary outcome measure, which should be measurable and possible to affect. Absence of reaction at baseline means that changes can only be detected as an increased reaction.
- physical activity
- longitudinal study
- psychosocial stress
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Contributors EA: involved in the protocol design and the overall planning of the study. Collected and analysed the data and wrote the manuscript. ASD: involved in the protocol design and the overall planning of the study. Revised the manuscript and provided final approval of the version to be published. MB: involved in the protocol design and the overall planning of the study. Revised the manuscript, added valuable intellectual content and provided final approval of the version to be published. LG: revised the manuscript, added valuable intellectual content and provided final approval of the version to be published. IHJ: involved in the protocol design and the overall planning of the study. Providing substantial contributions to the work and valuable intellectual content, and provided final approval of the version to be published.
Funding This trial was supported by funding from the Swedish Research Council for Health, Working Life and Welfare.
Competing interests None declared.
Patient consent Obtained.
Ethics approval The study was approved by the Regional Ethical Review Board, Gothenburg, Sweden, conducted according to the 1964 Declaration of Helsinki, number 917-12, and registered as a randomised controlled trial at ClinicalTrials.gov (ID no. NCT0251127).
Provenance and peer review Not commissioned; externally peer reviewed.