Radiographic axial spondyloarthritis, historically known as ankylosing spondylitis, is defined by inflammation of the axial skeleton, the entheses where tendons anchor to bone, and sometimes peripheral joints. Over years, the disease drives structural damage visible on X-rays, progressive loss of spinal mobility, and, in many patients, extra-musculoskeletal manifestations such as anterior uveitis, inflammatory bowel disease, or psoriasis. Because the condition typically begins in early adulthood, its cumulative toll on physical function can span an entire lifetime. Spinal mobility generally declines over time, and studies show that structural damage in the spine continues to accrue even after a decade of disease, particularly in male patients.

Exercise has long been a cornerstone of axSpA management, and structured programs have been shown to improve physical function, spinal mobility, muscle performance, and quality of life. Vigorous high-intensity exercise has even demonstrated effects on disease activity and inflammation in randomized trials. But those trials mostly enrolled younger patients, leaving a critical gap: what happens when people have lived with the disease for 25 years or more and are entering their sixties and seventies? The Gothenburg team set out to answer exactly that question, measuring not just how much patients moved, but how hard they moved, and how that related to their self-reported health.

The study drew on the Long-term Outcome Ankylosing Spondylitis (LOAS) cohort in western Sweden, originally recruited in 2009. Of the 210 patients enrolled at baseline, 141 returned for the 13-year follow-up conducted between May 2022 and February 2023. The participants, whose mean age was 60 years and who had lived with their diagnosis for an average of 25 years, underwent a remarkably comprehensive assessment battery. Physical function was quantified with the Bath Ankylosing Spondylitis Functional Index (BASFI), spinal mobility with the modified Bath Ankylosing Spondylitis Metrology Index (BASMI), leg strength with the Timed Stands Test (TST), which records how quickly a patient can rise from a standard chair ten times, and handgrip force with the Grippit dynamometer, which captures the mean force in Newtons over a ten-second squeeze.

Physical activity was self-reported across three dimensions: vigorous activity such as running, gymnastics, or sports that leave a person short of breath and sweaty; moderate activity such as brisk walking, gardening, or cycling; and sedentary behavior, measured as time spent sitting apart from sleep. Health status was scored with the ASAS Health Index (ASAS HI), a 0-to-17 scale where lower scores indicate better health, with a cutoff of 5 or below defining good health. Health-related quality of life was captured with the Short Form 36-Item survey (SF-36), which yields separate physical and mental component summary scores standardized against the general Swedish population. The researchers then used multivariable linear regression to untangle which of these factors independently predicted health outcomes, running the models both for the whole group and stratified by sex.

The headline finding was striking. Physical function and vigorous physical activity were the strongest determinants of both health status and quality of life. The regression models explained roughly half of the variation in the ASAS HI and in the physical component of the SF-36, and about 21 percent of the variation in the mental component. In correlation analyses, BASFI showed strong associations with both health status and physical quality of life, with Spearman correlation coefficients of 0.69 and minus 0.66 respectively. Spinal mobility, muscle function, and vigorous activity showed weaker but still significant links. Age itself correlated with declining mobility, weaker legs, and reduced grip strength, but the exercise signal persisted even after accounting for these demographic factors.

Sex differences added an intriguing layer. Male participants displayed significantly greater handgrip force and reported more vigorous physical activity than females. In the male subgroup, better leg strength also emerged as an independent predictor of better health status, while in the female subgroup, greater handgrip force and more moderate physical activity played that role. For mental quality of life, vigorous activity, better physical function, and younger age predicted better outcomes in the total group and among women, but among men only physical function mattered, and the model explained just 8 percent of the variation in their mental scores, compared with 35 percent in women. The authors note that female participants showed a non-significant trend toward poorer mental health scores than males.

Perhaps the most encouraging result is how well this cohort was actually doing. Sixty-two percent of participants reported good health status on the ASAS HI, and only four individuals, or 2.8 percent, fell into the poor health category. When adjusted for age and compared with reference values from the general population, 55 percent scored physical function within the range of healthy controls, and 45 percent maintained spinal mobility within normal limits. Muscle function was even more preserved: 82 percent performed within the normal range on the Timed Stands Test and 91 percent on handgrip force. Moreover, 77 percent of participants met the World Health Organization guidelines for health-enhancing physical activity, exceeding the 66 percent reported for the general Swedish population aged 30 to 84, and surpassing previous axSpA cohorts in which adherence estimates ranged from 17 to 71 percent.

The finding that vigorous exercise outperformed moderate daily activity in predicting health outcomes aligns with a growing body of evidence. Previous randomized trials have shown that high-intensity exercise reduces disease activity and improves fatigue, sleep, and mood in axSpA patients, and a recent meta-analysis concluded that aerobic exercise programs lower C-reactive protein, a marker of systemic inflammation. Interviews with patients who engage in high-intensity training reveal that while the exercise is perceived as challenging for both body and mind, the rapid physical benefits strengthen confidence in one’s own body and transform motivation to keep exercising. Notably, prior research comparing patients with healthy controls using accelerometer technology found that light and moderate activity levels were similar between groups, but patients reported significantly less vigorous activity, making this study’s high participation in intense exercise all the more remarkable.

The authors are careful to note the study’s limitations. As a cross-sectional analysis, it cannot establish causality; it is possible that healthier patients simply find it easier to exercise vigorously. The surviving cohort of 141 may also represent a selected group whose health literacy and lifestyle differ from the original 210 patients. Self-reported physical activity can be both overestimated and underestimated, and differences in how studies measure activity complicate cross-study comparisons. Still, the message is clear and potentially practice-changing: older individuals with long-standing r-axSpA can and do engage in vigorous physical activity, and those who do report markedly better health. The researchers call for randomized controlled trials of vigorous exercise specifically in older axSpA populations, a group that has been almost entirely absent from high-intensity exercise research to date. For patients and clinicians alike, the study suggests that the prescription for a stiff spine may need a higher dose of intensity than conventionally assumed.

Subject of Research: The association between vigorous physical activity, physical function, and health outcomes in older patients with long-standing radiographic axial spondyloarthritis

Article Title: Vigorous physical activity and physical function are strongly associated with better health in patients with long-standing radiographic axial spondyloarthritis

Article References: Feldthusen, C., Hallström, M., Hulander, E., Deminger, A., & Forsblad-d’Elia, H. (2026). Vigorous physical activity and physical function are strongly associated with better health in patients with long-standing radiographic axial spondyloarthritis. PLOS One, 21(10), e0360248. https://doi.org/10.1371/journal.pone.0360248

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360248

Keywords: axial spondyloarthritis, ankylosing spondylitis, vigorous exercise, physical function, quality of life, rheumatology, spinal mobility, muscle strength, health status, PLOS One, physical activity guidelines, older adults