Maximal exercise tolerance, objective trunk strength and mobility measurements in axial spondyloarthritis.

OBJECTIVE: Although exercise therapy is safe, effective and recommended within the nonpharmacological treatment in axial spondyloarthritis (axSpA), guidelines regarding type and dosage lack. Insufficient knowledge about physical and physiological parameters makes designing effective exercise programs challenging. Therefore, the goal was to simultaneously assess trunk strength, spinal mobility and the axSpA patients' cardiorespiratory fitness.

METHODS: In a cross-sectional study, 58 axSpA patients (mean age:40.8years, 50% males, mean symptom duration:10.3years) performed maximal cervical and trunk mobility and isometric strength tests in all planes (David Back Concepts devices) and a maximal cardiopulmonary bicycle exercise test (n=25). Mobility and strength data were compared to healthy reference data. Cut-off values for clinical CPET interpretation were used to judge normality. Patients were compared based on radiographic involvement and symptom duration.

RESULTS: Both strength (p≤0,017) and mobility (p≤0,001) were significantly lower for the axSpA patients compared to reference. Strength deficits were comparable between the radiographic and nonradiographic group (p>0,05 except trunk extension p=0,029), whereas mobility showed higher deficits in the radiographic group (cervical extension p=0,017 and rotation p=0,005 and trunk extension p=0,034 and rotation p=0,029), regardless of symptom duration. Similarly, symptom duration positively affected oxygen pulse (p=0,027), relative anaerobic threshold (p=0,020) and aerobic capacity (p=0,021).

CONCLUSION: Strength is more affected than mobility when compared to healthy controls. Likewise, mainly the metabolic component of aerobic capacity is impaired, affecting cardiopulmonary fitness. These findings indicate that future personalized exercise programs in axSpA patients should incorporate exercises for cardiopulmonary fitness next to strength and mobility training.