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Luder G.1,2, Mueller Mebes C.1, Haupt Bertschy B.1, Verra M.L.1, Aeberli D.3, Baeyens J.-P.2
1Bern University Hospital, Department of Physiotherapy, Berne, Switzerland, 2Vrije Universiteit Brussel, Physical Education and Physiotherapy, Brussels, Belgium, 3Bern University Hospital and Bern University, Department of Rheumatology, Clinical Immunology and Allergology, Berne, Switzerland
Background: Little is known about the management of persons with generalized joint hypermobility (GJH). Affected persons are often restricted in performing sports or leisure activities, as well as during work, due to pain and disability. Adequate muscle strength for movement control might be an important issue to overcome these restrictions. Resistance training has the possibility to improve muscle strength, but so far no study examined the influence of resistance training on strength and muscle size in women with GJH.
Purpose: The main goal was to investigate the effects of a 12 week resistance training in women with GJH on strength and muscle size. Additionally the influence on daily function and disability was investigated.
Methods: This RCT included 51 hypermobile women (mean age 26.5, sd 4.5 years) with a Beighton-score of six or more. 27 women performed a structured resistance training twice weekly for 12 weeks and 24 women did not exercise. Outcome measurements included maximum isometric strength (MVC) of knee extensors and flexors, muscle cross-sectional-area (mCSA) of the thigh at 33% above knee and the self-reported questionnaire SF-36. Data were analysed on an intention-to-treat basis using MANOVA with a significance level of p=0.05. Results are presented as mean difference between groups with 95% confidence intervals (CI) and the respective effect size (es).
Results: Both groups were comparable at baseline. The MANOVA revealed no significant difference in any of the five main variables. The difference of change between groups for maximum knee extensor strength was 43.9 N (CI -4.2 to 92.2, es=0.36), for knee flexors 29.2 N (CI -5.9 to 64.18, es=0.33) in favour of the training group. Regarding mCSA mean difference of change was 131.2 mm2 (CI -13.0 to 275.3, es=0.37) in favour for the training group. Concerning the SF-36 for the physical component summary score mean difference of change was 0.5 (CI -1.6 to 2.6, es=0.09) and for the mental component summary -4.2
(CI -0.8 to -7.5, es=0.50), thus favouring the control group.
Conclusion(s): The 12-week resistance training did not change isometric knee muscle strength or mCSA of the thigh in women with GJH. High standard deviations were seen, illuminating the high variability between the subjects in both groups, and maybe responsible for the non-significant result. Another possible reason for the lack of measured difference in strength might be that training was dynamic, while the measurement was isometrically. Furthermore, the analysis of the training protocols showed that several of the study participants did exercise with low resistance. As example in unilateral leg press the mean resistance of all women who exercised was 83% of body weight (range 65-160%) in the last training session. Therefore only three instruction sessions during the 12 weeks were probably insufficient to gain muscle mass and to keep motivation to exercise at the personal strength limit.
Implications: Resistance training did not clearly change strength and muscle mass in women with GJH. Maybe they need closer supervision and guidance during training to keep motivation and to use enough resistance for a clear gain in muscle strength and muscle mass.
Funding acknowledgements: No external financial support was given for this study.
Topic: Rheumatology
Ethics approval: The study was approved by the Ethics Committee of Canton Bern (222/12). The trial is registered as ISRCTN9022454.
All authors, affiliations and abstracts have been published as submitted.
