Aquatic Exercise for Ankylosing Spondylitis: Evidence from a Network Meta-analysis

Ankylosing spondylitis (AS), also known as axial spondyloarthritis, is a chronic inflammatory disease primarily affecting the sacroiliac joints and spine. Progressive stiffness, pain and reduced spinal mobility often lead to impaired physical function and decreased quality of life. Exercise is now regarded as a cornerstone of treatment alongside pharmacological management.

A 2025 systematic review and network meta-analysis compared multiple exercise modalities to determine which type of exercise provides the greatest clinical benefit for people with ankylosing spondylitis. Unlike conventional meta-analyses that compare only two interventions at a time, a network meta-analysis allows simultaneous comparison and ranking of several interventions.

Study objective

The review aimed to compare the effectiveness of different exercise interventions on:

• Disease activity (BASDAI)
• Functional ability (BASFI)
• Spinal mobility (BASMI)
• Quality of life (ASQoL)

The goal was to identify the most effective exercise programme for clinical practice.

Study design

Researchers systematically searched six international databases up to March 2025.

The review included:

• 48 clinical studies
• 3,140 participants
• Publications between 2002 and 2024

Exercise programmes were classified into six categories:

• Aquatic Stretching Exercise (ASE)
• Aquatic Aerobic Exercise (AAE)
• Land Aerobic Exercise (LAE)
• Land Stretching Exercise (LSE)
• Muscle Exercise (ME)
• China Health Campaign (Tai Chi, Baduanjin, Qigong)

The interventions were compared using a frequentist network meta-analysis with SUCRA rankings to determine the probability that each intervention was the most effective.

Why aquatic exercise may be particularly beneficial

The authors explain that aquatic exercise offers several unique therapeutic advantages.

Reduced joint loading

Buoyancy decreases weight-bearing forces on painful spinal and peripheral joints, allowing patients to exercise with less discomfort.

Improved movement

Reduced gravitational loading enables greater spinal mobility and larger movement amplitudes that may be difficult to achieve on land.

Warm-water effects

Warm water helps reduce pain and muscle stiffness while promoting relaxation.

Low-impact conditioning

Patients with severe pain or limited mobility can exercise at higher volumes without excessive mechanical stress.

These characteristics make aquatic exercise particularly suitable for individuals with active disease or advanced functional limitations.

Main findings

Disease activity (BASDAI)

Compared with usual care, several exercise modalities significantly reduced disease activity.

Aquatic Stretching Exercise (ASE)

• Mean difference: −1.42
• Highest effectiveness ranking
• SUCRA: 85.5%

Land Aerobic Exercise

• Mean difference: −0.94

Land Stretching Exercise

• Mean difference: −0.49

Aquatic Stretching Exercise ranked as the most effective intervention for reducing disease activity.

Functional ability (BASFI)

Aquatic Stretching Exercise again demonstrated the strongest improvements.

Significant improvements

• Aquatic Stretching Exercise: −1.74
• Aquatic Aerobic Exercise: −0.90
• Land Aerobic Exercise: −0.74
• Land Stretching Exercise: −0.54
• Muscle Exercise: −0.48

Aquatic Stretching Exercise achieved an exceptional SUCRA score of 99.6%, indicating the highest probability of being the best intervention for improving physical function.

Spinal mobility (BASMI)

Several interventions improved spinal mobility.

The highest-ranked interventions were:

• China Health Campaign (Tai Chi/Baduanjin): SUCRA 78.7%
• Aquatic Stretching Exercise
• Land Aerobic Exercise

Although China Health Campaign ranked first for spinal mobility, Aquatic Stretching Exercise also demonstrated statistically significant improvements.

Quality of life (ASQoL)

Only two interventions demonstrated statistically significant improvements in quality of life.

Aquatic Stretching Exercise

• Mean difference: −3.67
• SUCRA: 88.4%

Land Aerobic Exercise

• Mean difference: −2.64

Aquatic Stretching Exercise again ranked as the most effective intervention.

Overall ranking of exercise interventions

Across all outcome measures, Aquatic Stretching Exercise consistently performed best.

Overall, aquatic stretching emerged as the most consistently effective intervention for people with ankylosing spondylitis.

Clinical implications

The findings suggest aquatic therapy should be strongly considered for patients who experience:

• Moderate to severe pain
• Morning stiffness
• Reduced spinal mobility
• Functional limitations
• Difficulty tolerating land-based exercise
• Reduced quality of life

Aquatic exercise may also serve as an effective bridge toward more intensive land-based rehabilitation as symptoms improve.

Limitations

The authors acknowledge several important limitations:

• Considerable variation in exercise protocols
• Differences in intervention duration (2–48 weeks)
• Limited number of aquatic studies compared with land-based exercise
• Blinding was rarely possible, increasing risk of bias
• Most comparisons relied on indirect evidence

Despite these limitations, this represents the largest comparative synthesis of exercise interventions for ankylosing spondylitis published to date.

Conclusion

This 2025 systematic review and network meta-analysis demonstrates that Aquatic Stretching Exercise (ASE) is the most effective exercise modality for improving overall outcomes in ankylosing spondylitis. Compared with land-based exercise, aquatic stretching consistently ranked highest for reducing disease activity, improving physical function and enhancing quality of life, while aquatic exercise in general offers a safe, low-impact environment that enables effective rehabilitation for patients with pain, stiffness and limited mobility. These findings support incorporating aquatic therapy as a key component of multidisciplinary management for ankylosing spondylitis.