Association between core stability and physical function, functional performance in patients with systemic sclerosis

Objective: To investigate the association of core stability with physical function and functional performance in patients with systemic sclerosis (SSc). Methods: Forty patients who met the American College of Rheumatology / European League Against Rheumatism 2013 classification criteria for SSc were included in the cross-sectional study. For evaluation of core stability, trunk muscle endurance and trunk muscle strength were assessed. Trunk extensor and trunk flexor endurance tests were used for assessment of trunk muscle endurance. Trunk muscle strength was measured with a hand-held dynamometer and modified sit-up test. To measure physical function the Health Assessment Questionnaire Disability Index (HAQ-DI) and to measure functional performance 6-minute walking test (6MWT) and sit-to-stand test (STS) were used. Results: Patients with SSc had lower mean trunk extensor and flexor endurance test times (49.87 +/- 30.81 and 32.17 +/- 15.42 seconds, respectively), modified sit-up test repetition (17.42 +/- 7.81) and trunk extensor and flexor muscle strength (7.48 +/- 2.29 kg and 6.20 +/- 1.68 kg, respectively) when compared to the reference values in healthy individuals. All measurements were used to evaluate core stability associated with HAQ-DI score, 6DMWT walking distance and STS test duration (all P < .05). Conclusion: Patients with SSc have markedly reduced core stability and this negatively affects the physical function and functional performance. Therefore, this study highlights the importance of trunk muscle in patients with SSc. We suggest that not only upper-lower extremity muscles, but also trunk muscle strength and endurance should be measured and core stability exercises can be added to the training programs to maintain and/or improve physical functions and functional performance in SSc patients.