Aquatic Therapy for Knee Hyperextension After Stroke

Stroke is one of the leading causes of long-term disability worldwide. One of the most common gait abnormalities following stroke is knee hyperextension (genu recurvatum), which affects approximately 65% of stroke survivors. This abnormal movement pattern results from impaired proprioception, muscle weakness, spasticity and poor neuromuscular control, reducing walking efficiency while increasing the risk of falls and degenerative knee injury.

A 2025 randomized controlled study investigated whether combining aquatic proprioceptive training with bilateral prowling exercises would improve gait and reduce knee hyperextension more effectively than performing the same exercises on land.

Study objective

The purpose of the study was to compare:

Conventional physiotherapy plus land-based proprioceptive training and bilateral prowling
Conventional physiotherapy plus aquatic proprioceptive training and bilateral prowling

The primary outcomes were:

Wisconsin Gait Scale (WGS)
Knee hyperextension angle measured with Kinovea motion-analysis software

Assessments were performed at baseline and after 2, 4 and 6 weeks.

Study design

Twenty-eight adults with chronic stroke completed the study.

Participants were randomly allocated into:

Group A: Land-based rehabilitation (14 participants)
Group B: Aquatic rehabilitation (14 participants)

Both groups received identical conventional physiotherapy. The only difference was whether the proprioceptive training and bilateral prowling exercises were performed on land or in water.

Aquatic intervention

The aquatic programme lasted 6 weeks and progressed over time.

Weeks 1–3

Participants performed:

Single-leg stance
Squats
Dynamic squats
Marching
Lunges
Single-leg squats
10 repetitions of each exercise
Five rounds of bilateral prowling with approximately 15–20° knee flexion

Weeks 4–6

Progression included:

Increasing all exercises to 20 repetitions
Increasing bilateral prowling to 10 rounds

Exercises were performed in an aquatic environment under supervision.

Why water may improve rehabilitation

The authors describe several mechanisms explaining why aquatic therapy may enhance recovery after stroke.

Buoyancy

Water reduces effective body weight, allowing individuals with weakness and impaired balance to perform movements that may be difficult or unsafe on land.

Hydrostatic pressure

Continuous pressure around the limbs enhances proprioceptive input and contributes to improved postural stability and circulation.

Water resistance

Viscosity provides multidirectional resistance throughout movement, promoting muscle strengthening and neuromuscular control.

Thermal effects

Warm water promotes muscle relaxation, reduces spasticity and pain, and creates an environment that facilitates motor relearning.

Results

Improvement in gait quality

Both rehabilitation programmes significantly improved walking.

However, the aquatic group achieved greater improvements.

Wisconsin Gait Scale

Land-based rehabilitation

Baseline: 27.2
Week 6: 21.1
p = 0.002

Aquatic rehabilitation

Baseline: 27.9
Week 6: 19.4
p = 0.0001

Lower scores indicate better gait quality, demonstrating a larger improvement in the aquatic group.

Improvement in knee hyperextension

Knee extension angles also improved in both groups.

Land group

Baseline: −13.6°
Week 6: −10.3°

Aquatic group

Baseline: −14.0°
Week 6: −8.4°

Between-group analysis demonstrated significantly greater improvement following aquatic rehabilitation (p = 0.0001).

Why bilateral prowling may work

Bilateral prowling requires walking while maintaining approximately 15–20° of knee flexion throughout stance.

According to the authors, this technique:

Prevents excessive knee extension
Increases hamstring activation
Encourages quadriceps endurance
Promotes improved knee alignment during walking
Reinforces more normal gait mechanics

When combined with aquatic therapy, these effects may be amplified by the enhanced sensory feedback provided by water.

Proposed mechanisms for the superior aquatic results

The authors suggest several reasons why aquatic therapy produced better outcomes than land-based therapy.

Enhanced proprioception

Hydrostatic pressure continuously stimulates cutaneous and deep sensory receptors, improving joint position awareness.

High-repetition practice

Reduced joint loading allows patients to safely perform more repetitions without excessive fatigue.

Improved muscle co-contraction

Water resistance promotes coordinated activation of the quadriceps and hamstrings, improving dynamic knee stability.

Reduced fear of falling

The supportive environment encourages patients to practise larger, more confident movements, which may enhance motor learning and neuroplasticity.

Sensorimotor retraining

The combination of buoyancy, resistance and continuous sensory feedback may facilitate reorganization of central nervous system motor patterns.

Clinical implications

Aquatic therapy appears particularly valuable for post-stroke patients presenting with:

Knee hyperextension (genu recurvatum)
Proprioceptive deficits
Gait abnormalities
Muscle weakness
Balance impairments
Fear of falling
Difficulty tolerating weight-bearing exercise

The study suggests that combining aquatic proprioceptive training with bilateral prowling may accelerate improvements in gait quality compared with identical exercises performed on land.

Limitations

Several limitations should be considered:

Small sample size (28 participants)
Single-centre study
Six-week intervention period
No long-term follow-up
Functional outcomes beyond gait were not evaluated

Although statistically significant differences were found, larger multicentre randomized trials are needed before definitive clinical recommendations can be made.

Conclusion

This randomized controlled study found that aquatic proprioceptive training combined with bilateral prowling exercises produced greater improvements in gait quality and significantly reduced knee hyperextension compared with the same rehabilitation programme performed on land. The supportive properties of water—including buoyancy, hydrostatic pressure, viscosity and thermal effects—appear to enhance proprioceptive retraining, improve dynamic knee stability and facilitate safer, more effective gait rehabilitation after stroke.