Objective: Reduced maximal muscle strength and strength endurance has been found in patients with hypermobile Ehlers-Danlos syndrome/Hypermobility Spectrum Disorder (hEDS/HSD) and is recognized as a common associated feature of the disorder. However, it is currently not documented to which extent these parameters change over time. Therefore, an 8-year follow-up study was performed to investigate this evolution.
Methods: Thirty female patients (mean age: 41 years) with hEDS/HSD and 17 controls participated at baseline and eight years later. Maximal muscle strength and strength endurance tests of the knee flexors and extensors (Biodex), and two lower limb posture maintenance tests were performed to evaluate static strength endurance. In addition, muscle mass and density were evaluated by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography.
Results: Maximal muscle strength and strength endurance were significantly lower at both baseline and follow-up in the hEDS/HSD group compared to the control group (p≤0.007). Maximal muscle strength of the knee flexors (decreased in the control group: pɳ2 : 0.139), strength endurance of the knee extensors (decreased in the hEDS/HSD group and increased in the control group: pɳ2 : 0.244) and muscle density (decreased in the hEDS/HSD group: pɳ2 : 0.263) showed a significantly different evolution over eight years. No other significant differences in evolution were found.
Conclusion: Decreased muscle strength was identified at both time points in patients with hEDS/HSD. The evolution of most muscle strength parameters over time did not significantly differ between groups. Future studies should focus on effectiveness of different types of muscle training strategies in hEDS/HSD patients.