Swimming is an excellent activity for individuals seeking relief from knee discomfort and for use in rehabilitation. The aquatic environment offers a low-impact method of exercise, allowing movement and muscle strengthening without the jarring forces of land-based activities. This form of exercise provides a safe space to maintain cardiovascular health while reducing the load placed directly onto the knee joint.
The Biomechanics of Water
The therapeutic benefits of aquatic exercise stem from the unique physical properties of water. Buoyancy, the upward force exerted by the water, significantly counteracts gravity’s downward pull on the body. Submerging to chest height reduces the load on the lower limbs by approximately 60% to 75% compared to standing on land. This reduction in weight-bearing stress allows for a greater range of motion and muscle activation with less compressive force on the knee’s cartilage and ligaments.
Water also provides hydrostatic pressure, the force exerted uniformly against the body’s submerged surfaces. This pressure acts like a gentle, full-body compression garment, which is beneficial for managing inflammation. The constant external pressure helps reduce swelling (edema) within the joint and surrounding tissues. Reduced swelling leads directly to a decrease in pain and improved joint mobility.
Water’s viscosity provides resistance to movement in all directions, which helps build muscular strength. Unlike weights, water resistance requires muscles to work during both the push and pull phases of an action. This fluid resistance allows for controlled strengthening of the quadriceps and hamstrings, the muscles that stabilize the knee. The resistance level can be modulated by changing the speed of movement or the surface area engaging the water.
Recommended Aquatic Exercises
Activities beneficial for managing knee pain focus on rhythmic, controlled movements that utilize the water’s properties. Water walking is a simple yet effective starting point, performed in water that is waist- to chest-deep. Walking forward, backward, and sideways utilizes the water’s resistance to build strength in the muscles supporting the knee.
Simple range-of-motion exercises can be performed while holding the side of the pool for stability. These include gentle knee bends, where the knee is slowly flexed and extended, or single-leg swings. The water’s support makes these movements less painful than attempting them on land, encouraging consistent practice.
If swimming laps, the freestyle flutter kick is acceptable, provided the technique originates from the hips. The movement should be gentle, continuous, and fluid, with only a soft bend at the knee. This hip-driven motion engages the core and gluteal muscles, which are important for knee stability, minimizing stress on the joint. Using a pull buoy placed between the thighs can eliminate the need to kick entirely, allowing focus solely on arm movement and core stability.
Strokes and Movements to Avoid
While swimming is beneficial, specific strokes and movements can exacerbate existing knee conditions. The breaststroke whip kick is frequently identified as a potential cause of knee discomfort, often called “Breaststroker’s knee.” The kick requires the knee to move into external rotation, abduction, and forceful extension. This combination places significant, repetitive valgus stress and torque on the medial (inner) side of the joint, which can irritate the medial collateral ligament (MCL).
Caution should also be exercised during pool turns, especially forceful push-offs from the wall. Planting the feet and pushing off involves the knee moving into a high degree of flexion under sudden, high-shear stress. This compressive load can aggravate conditions such as patellofemoral pain or meniscal injuries. Instead of a forceful push-off or a flip turn, a gentle, open turn with a light step-off or walk-off from the wall is recommended.
The use of training tools, such as kickboards, can sometimes lead to excessive strain on the knee. Using a kickboard to isolate the legs can unintentionally encourage a more forceful or less efficient kick, increasing joint forces beyond a therapeutic level. Movement should always be smooth and purposeful rather than focused on maximum speed or power.
When to Seek Professional Guidance
Before starting any new exercise program for chronic pain, consult a healthcare provider, such as a doctor or physical therapist. They can provide clearance and help tailor an aquatic routine to suit the specific nature of the knee problem. A medical professional can distinguish between the muscle soreness of a new workout and true joint pain.
It is important to monitor symptoms closely during and after time in the water. If an exercise causes sharp, stabbing, or increasing joint pain, the activity should be stopped immediately. A dull ache or muscle fatigue is acceptable, but any signal suggesting joint irritation should be heeded to prevent further damage.
The success of aquatic exercise relies on proper structuring of the session. A brief warm-up, such as slow walking in the water, prepares the muscles and joints for movement. Following the main exercise period, a gentle cool-down helps to gradually lower the heart rate and stretch the muscles. Incorporating a specialist who understands swimming biomechanics can ensure exercises are performed with the correct form to maximize benefit and maintain safety.