Defining and reporting exercise intensity in interventions for older adults: a modified Delphi process

Many exercise studies, including older adults, do not report all relevant exercise characteristics. Especially the description of exercise intensity is missing and mostly not controlled. This leads to difficulties in interpreting study results and summarizing the evidence in systematic reviews or meta-analyses. Therefore, the aim of the present Delphi study was to gain recommendations about the categorization of exercise intensity and for the conducting and reporting of characteristics in future intervention studies with older adults by experts in exercise science and physiology. Two hundred ninety-seven international interdisciplinary participants from an EU COST action were invited to participate in three rounds of online questionnaires in April/May 2023. Up to N = 93 experts participated in each round. Round 1 included open-ended questions to solicit possible recommendations and categorizations for light, moderate, vigorous, and high intensity. In round 2, the experts rated their agreement using Likert scales (1–10) on the revealed categories and recommendations. Clusters with a higher average rating of M = 8.0 were summarized into round 3. In the final round, the results were presented for a final rating of agreement (based on a simple majority > 50%). In round 1 a total of 416 qualitative statements were provided from thirteen questions. From round 1 to round 3, a total of 38 items were excluded, with 205 items retained for the final consensus. In round three 37 participants completed the whole questionnaire. The experts showed overall agreement on the final categorizations with 6.7 to 8.8 out of 10 points on the Likert scale. They also showed broad consensus on the relevance of reporting exercise intensity and the recommendations for future conducting and reporting of study results. However, exercise types such as yoga, balance, and coordination training led to conflicting results for categorization into light or moderate. The results of the current survey can be used to classify the intensity of exercise and suggest a practical approach that can be adopted by the scientific community and applied when conducting systematic reviews and meta-analysis articles when vital and objective information regarding exercise intensity is lacking from the original article. - Experts highlight the importance of reporting exercise intensity for individualization and participant safety - International interdisciplinary participants with expertise in exercise gained a common understanding of the categorization of exercise intensity for future intervention studies with older adults. - Conflicting results for exercise types such as yoga, balance, and coordination training present categorization challenges