High intensity exercise for 3 months reduces disease activity in axial spondyloarthritis (axSpA): a multicenter randomised trial of 100 patients

Key points

1. 01ASDAS disease activity score fell by 0.6 points more in the exercise group than controls (p<0.001), and BASDAI fell by 1.2 points more (p<0.001)
2. 0252% of exercisers achieved a 20% improvement in disease activity versus only 10% of controls; the number needed to treat was 3
3. 03Peak oxygen uptake (VO2peak) improved by 2.7 mL/kg/min more in the exercise group (p<0.001), suggesting meaningful cardiovascular benefit
4. 04Physical function (BASFI) improved by 0.9 points more in exercisers (27% vs 11% change, p<0.001)
5. 05High-intensity exercise was safe: no disease flares were recorded and only minor adverse events occurred

How it was conducted

Design

Assessor-blinded multicentre randomised controlled trial (RCT) across 4 rheumatology centres in Norway and Sweden

Participants

100 adults aged 18-70 with axSpA, moderate to high disease activity (BASDAI >=3.5), and no regular exercise in the past 6 months

Intervention

3 supervised sessions per week for 12 weeks: 2 physiotherapist-led high-intensity cardiorespiratory and strength sessions plus 1 independent cardio session

Control

Standard care with instruction to maintain usual physical activity level

Primary outcomes

Disease activity measured by ASDAS-CRP and BASDAI at 3 months

Analysis

Intention-to-treat using ANCOVA adjusted for baseline values and study centre

What they found

• ASDAS: estimated mean group difference -0.6 (95% CI -0.8 to -0.3), p<0.001; exercise group changed from 2.6 to 1.9 vs control group 2.7 to 2.6
• BASDAI: estimated mean group difference -1.2 (95% CI -1.8 to -0.7), p<0.001; exercise group changed from 4.9 to 3.3 vs control 5.3 to 4.8
• ASAS20 response: 52% (25/48) in exercise group vs 10% (5/49) in control; absolute increased benefit 42% (95% CI 25% to 58%), NNT 3 (95% CI 2 to 4)
• ASAS40 response: 38% (18/48) in exercise group vs 4% (2/49) in control; absolute increased benefit 33% (95% CI 19% to 48%), NNT 3 (95% CI 2 to 5)
• VO2peak: mean group difference +2.7 mL/kg/min (95% CI 1.6 to 3.8), p<0.001; 8.2% difference in change between groups
• Physical function BASFI: mean group difference -0.9 (95% CI -1.3 to -0.4), p<0.001
• Spinal mobility BASMI: mean group difference -0.3 (95% CI -0.5 to -0.06), p=0.016
• Waist circumference: mean group difference -1.7 cm (95% CI -3.2 to -0.2), p=0.031 (in those with elevated baseline waist)
• CRP: significant group difference in favour of exercise group (p=0.041, Mann-Whitney); ESR difference not significant (p=0.066)
• Fatigue sub-score (BASDAI): group difference -1.4 (95% CI -2.2 to -0.6), p<0.001
• Morning stiffness sub-score: group difference -1.7 (95% CI -2.4 to -1.0), p<0.001

Limitations

• No blinding of participants was possible, so a psychological (attention) effect on patient-reported outcomes cannot be ruled out
• Only short-term (3-month) effects were measured; long-term sustainability is unknown
• Motivated patients may have self-selected into the study, potentially limiting generalisability to less motivated populations
• About 40% of participants were on stable TNF-inhibitor treatment, which may have influenced the observed treatment effects

Why it matters

For patients

People with axial spondyloarthritis can safely perform high-intensity exercise and expect meaningful reductions in pain, fatigue, stiffness, and improvements in their ability to function day-to-day.

For clinicians

High-intensity cardiorespiratory and strength training should be considered a core component of axSpA management alongside pharmacotherapy, offering disease-modifying and cardiovascular benefits with a low number needed to treat (3).

For readers

This RCT directly challenges the longstanding clinical concern that vigorous exercise is harmful in axSpA, providing robust evidence that it is both safe and effective.