Effect of resistance training on muscle properties and function in women with generalized joint hypermobility: a single-blind pragmatic randomized controlled trial

BACKGROUND: Generalized joint hypermobility is defined as an excessive range of motion in several joints. Having joint hypermobility is not a pathology, but when associated with pain and other symptoms, it might affect health and function. Evidence for physiotherapy management is sparse and resistance training might be a possible intervention. Thus, the effects of 12-week resistance-training on muscle properties and function in women with generalized joint hypermobility were evaluated. METHODS: In this single-blind randomized controlled trial women between 20 and 40 years with generalized joint hypermobility (Beighton score at least 6/9) were included. Participants were randomly allocated to 12-week resistance training twice weekly (experimental) or no lifestyle change (control). Resistance training focused on leg and trunk muscles. Primary outcome was muscle strength; additional outcomes included muscle properties, like muscle mass and density, functional activities, pain and disability. Training adherence and adverse events were recorded. RESULTS: Of 51 participating women 27 were randomised to training and 24 into the control group. In each group 11 women had joint hypermobility syndrome, fulfilling the Brighton criteria, while 24 (89%) in the training group and 21 (88%) in the control group mentioned any pain. The mean strength of knee extensors varied in the training group from 0.63 (sd 0.16) N/bm before training to 0.64 (sd 0.17) N/bm after training and in the control group from 0.53 (sd 0.14) N/bm to 0.54 (sd 0.15) N/bm. For this and all other outcome measures, no significant differences between the groups due to the intervention were found, with many variables showing high standard deviations. Adherence to the training was good with 63% of participants performing more than 80% of sessions. One adverse event occurred during training, which was not clearly associated to the training. Four participants had to stop the training early. CONCLUSIONS: No improvement in strength or muscle mass by self-guided resistance training was found. Low resistance levels, as well as the choice of outcome measures were possible reasons. A more individualized and better guided training might be important. However, program adherence was good with few side effects or problems triggered by the resistance training. TRIAL REGISTRATION: This trial was prospectively registered in the ISRCTN registry (www.isrctn.com, BMC, Springer Nature) on July 16, 2013 as ISRCTN90224545. The first participant was enrolled at October 25, 2013. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13102-021-00238-8.