Aquatic Therapy for Degenerative Disc Disease

Degenerative disc disease (DDD) is one of the leading causes of chronic low back pain and spinal disability worldwide. As intervertebral discs lose water and height over time, spinal loading increases, often resulting in pain, stiffness and reduced mobility. A 2025 narrative review explored whether simulated microgravity, including aquatic therapy, may provide a novel approach to reducing spinal compression and supporting disc health.

Why aquatic therapy may benefit degenerative disc disease

Healthy intervertebral discs rely on adequate hydration to maintain their shock-absorbing properties. Continuous gravitational loading gradually compresses the spine, reducing disc height and water content.

Aquatic therapy creates a partially weightless environment through buoyancy, reducing axial loading on the spine. According to the review, this unloading may temporarily promote disc rehydration, reduce nerve compression and improve spinal mechanics while allowing patients to move with significantly less discomfort.

Understanding simulated microgravity

The review describes several methods that mimic the unloading experienced in space.

These include:

• Water immersion therapy
• Dry immersion
• Parabolic flight

Among these approaches, water immersion therapy is considered the most practical and clinically accessible because therapeutic pools are already widely available in rehabilitation settings.

How water immersion affects the spine

Reduced spinal compression

Buoyancy counteracts body weight, reducing compressive forces acting on the vertebral column.

The review explains that decreasing axial loading allows the intervertebral discs to absorb more fluid, temporarily increasing disc hydration while reducing mechanical stress on spinal structures.

Improved disc hydration

One of the central findings of the review is that unloading promotes an osmotic influx of water into the intervertebral discs.

Experimental studies included in the review demonstrated:

• Increased disc water content
• Increased intervertebral disc volume
• Temporary restoration of disc height

Improved hydration may help restore the shock-absorbing function of degenerating discs.

Reduced nerve compression

As discs regain hydration and height, pressure on surrounding nerve roots may decrease.

The authors suggest that improved disc height may relieve symptoms associated with nerve compression, including pain, numbness and radicular symptoms. However, they emphasise that this hypothesis still requires confirmation in clinical trials.

Biological mechanisms

The review discusses several biological mechanisms that may contribute to spinal recovery during unloading.

Increased proteoglycan production

Proteoglycans are responsible for attracting and retaining water within the nucleus pulposus.

Several experimental studies suggest that short-term unloading may stimulate proteoglycan synthesis, helping restore the disc’s ability to retain water and maintain mechanical function.

Activation of tissue repair pathways

The authors describe evidence that simulated microgravity may activate the TGF-β/Smad3 signalling pathway, an important regulator of tissue repair and extracellular matrix production.

Although these findings currently originate primarily from laboratory studies, they provide a possible biological explanation for the regenerative effects observed during spinal unloading.

Aquatic therapy in clinical rehabilitation

Unlike dry immersion or parabolic flight, aquatic therapy is already widely available in rehabilitation practice.

According to the review, water immersion may support rehabilitation by:

• Reducing spinal loading
• Promoting disc hydration
• Decreasing low back pain
• Facilitating early movement
• Allowing mobility and proprioceptive exercises in a reduced-load environment

The authors suggest aquatic therapy may be particularly valuable during conservative management of discogenic pain or as part of post-exercise recovery for athletes exposed to repetitive spinal loading.

Applications in sports medicine

The review highlights the potential value of aquatic therapy for athletes participating in sports involving high spinal loading, including:

• Weightlifting
• Wrestling
• Gymnastics
• American football

Temporary spinal unloading may help reduce cumulative mechanical stress while supporting recovery between training sessions and competitions.

Aquatic therapy should not be used alone

Although the authors describe promising physiological effects, they emphasise that aquatic therapy should be integrated into a comprehensive rehabilitation programme.

Recommended complementary interventions include:

• Core stabilisation exercises
• Proprioceptive training
• Functional rehabilitation
• Strength training
• Postural exercise programmes

The review concludes that unloading alone is unlikely to reverse degenerative disc disease without active rehabilitation addressing spinal stability and movement control.

Limitations

The evidence remains preliminary.

Of the nine studies included in this narrative review:

• Most were laboratory or animal studies.
• Human studies involved only small numbers of healthy volunteers.
• There is currently no high-quality clinical evidence demonstrating long-term benefits in patients with degenerative disc disease.

The authors also note that prolonged exposure to microgravity may have harmful effects, highlighting the importance of distinguishing short-term therapeutic unloading from long-duration spaceflight.

Conclusion

This narrative review suggests that aquatic therapy for degenerative disc disease may provide meaningful short-term spinal unloading by reducing axial compression and promoting intervertebral disc hydration. While the underlying biological mechanisms appear promising, current evidence is largely based on laboratory research and simulated microgravity models. Well-designed clinical trials are still needed before aquatic therapy can be considered a regenerative treatment for degenerative disc disease. At present, it should be viewed as a valuable component of a multidisciplinary rehabilitation programme rather than a standalone therapy.