Excentrisk och isometrisk styrkemätning av inåt- och utåtrotation i glenohumeralleden med handhållen dynamometer hos elitspelande tennisjuniorer

Assessment of shoulder strength is an important part of the clinical examination of the shoulder. Imbalances between agonists and antagonists of the shoulder can lead to increased risk of injury. To acquire information about strength imbalances a handheld dynamometer can be used to assess isometric and eccentric strength and to calculate inter muscular strength ratios.The purpose of the study was to calculate functional and isometric strength ratios in the rotatorcuff in adolescent elite tennis players and compare with a control group of non-overhead athletes and to evaluate the use of a control group. A handheld dynamometer was used to measure rotatorcuff strength in 30 elite adolescent tennis players compared to a control group of 29 non-overhead athletes of the same age. Outcome variables of interest were ER/IR strength ratios.The result of the study showed significant two-way interactions (side × group) for all ER/IR ratios. There were larger differences between the girls’ groups. Overall most participants had lower functional and isometric ratios in the dominant arm compared to the non-dominant arm with larger differences between the arms in the tennis groups and in the girls. There is risk for bias in using the non-dominant arm as control when measuring strength in the rotatorcuff.This study shows that there is a difference in functional and isometric ratios in elite tennis players compared with a control group of non-overhead athletes with largest differences in the girls and in the dominant arm. The study provides clinicians with reference values for ER/IR strength ratios in young tennis players and non-overhead athletes. Future studies in this area should use a control group instead of comparing with the non-dominant arm and expand the groups for higher statistical level of evidence.Validerat; 20160619 (global_studentproject_submitter