Background Juvenile idiopathic arthritis (JIA) is a chronic disease that occurs before the age of 16 years. It was shown that anaerobic exercise capacity, which is important for most daily activities in children such as jumping, hoping and climbing was diminished in JIA. Previous studies showed that anaerobic exercise capacity was related to well-being level, functional status, and aerobic exercise capacity in JIA. However, no data is available about the relationship between lower extremity muscle power and anaerobic exercise capacity in children with JIA.

Objectives To determine the possible relationships between lower extremity muscle strength and anaerobic capacity.

Methods Forty-six children with JIA (14 F, 32 M), with a mean age of 13.74±2.29 years (min-max: 9–17 years) were included in the study. Isometric lower extremity muscle strength was assessed with a hand-held dynamometer at the end points of knee flexion, knee extension, hip flexion and hip extension movements, which are generated from gross lower extremity muscles and important for anaerobic power. All the muscle testing was performed on the right leg. Anaerobic exercise capacity was measured performing a 30-second Wingate test. Both absolute and per kilogram values for peak power and average power were noted. The relationships between the parameters were determined with Pearson's correlation coefficient. (Relationship levels were interpreted as 0.05–0.30: low correlation; 0.30–0.40: low-moderate correlation; 0.40–0.60: moderate correlation; 0.60–0.75: good correlation; 0.75–1.00: good-excellent correlation.

Results All children completed the assessments without any adverse effects. Demographics, average isometric lower extremity muscle strengths and parameters related to the anaerobic exercise capacity testing were shown at Table 1. Moderate to good correlations were determined between isometric muscle strength and anaerobic exercise capacity parameters p<0.001 (Table 2).

Conclusions The results of this study suggested that lower extremity muscle strength might influence the anaerobic exercise capacity. Exercise regimes including lower extremity strengthening might help improving anaerobic exercise capacity in children with JIA.

Disclosure of Interest None declared