The sacroiliac (SI) joints connect the sacrum, a triangular bone at the base of the spine, to the pelvis’s iliac bones. These joints support the upper body’s weight and act as shock absorbers. SI joint pain, or dysfunction, arises from either excessive movement (hypermobility) or restricted movement (hypomobility), often causing discomfort in the lower back, buttocks, and sometimes radiating down the leg. Swimming is beneficial for managing this condition because it allows for movement and strengthening without the compressive forces of land-based exercises. The water environment minimizes the stress that often aggravates the SI joint.
How Water Buoyancy Affects SI Joint Stress
The physical properties of water offer biomechanical advantages that benefit individuals with SI joint pain. The upward force of buoyancy counteracts gravity, which significantly reduces the vertical load placed on the joints. When submerged to chest depth, the body is supported enough to reduce the weight bearing on the lower body by approximately 75%. This reduction in compression minimizes the stress and shear forces that typically aggravate a dysfunctional SI joint during activities like walking or running.
Exercising in water also introduces resistance, which is utilized for gentle muscle strengthening without high-impact movements. This resistance engages muscles during the pushing phase while avoiding the jarring eccentric phase common in land exercises. Furthermore, the hydrostatic pressure of the water acts uniformly across the submerged body, assisting in reducing inflammation and improving blood circulation. The warm temperature of many therapy pools can also enhance this effect by promoting muscle relaxation and increasing flexibility around the pelvis.
Recommended and Restricted Swimming Strokes
The suitability of a swimming stroke depends on the degree of pelvic and lumbar rotation it requires. Strokes that maintain a neutral spine and symmetrical movement pattern are safer for joint stability. The front crawl, or freestyle, can be adapted by focusing on smooth, minimal hip rotation. Swimmers should concentrate on keeping the body streamlined and performing a controlled, gentle flutter kick, avoiding forceful twisting motions required for breathing or propulsion.
The breaststroke is often restricted because the traditional “frog” kick involves an outward and circular motion of the hips that places excessive strain on the SI joint. This motion can compress or stretch the joint structures, increasing symptoms. Likewise, the butterfly stroke must be avoided due to its requirement for significant spinal hyperextension and powerful, undulating movements of the core and pelvis. These extreme ranges of motion are provocative for both hypermobile and hypomobile SI joint conditions.
A recommended modification is using a kickboard to isolate the legs for a simple flutter kick. This allows for strengthening the hip flexors and core muscles while the upper body remains stable, eliminating torso rotation. The backstroke is another beneficial option because it promotes an aligned body position and symmetrical movement, which helps stabilize the spine and gently works the surrounding muscles.
Low-Impact Aquatic Alternatives
For individuals experiencing a flare-up of pain or whose condition is too sensitive for modified swimming strokes, non-swimming aquatic exercises provide a safe entry point to physical activity. Water walking is an effective alternative, as the water’s resistance strengthens the supporting muscles while buoyancy unloads the joint. Walking forward, backward, and sideways in waist-deep water targets different muscle groups that contribute to pelvic stability.
Gentle core stabilization can be performed while holding the edge of the pool. Standing leg lifts, including hip abduction and adduction (moving the leg away from and toward the body), use the water’s resistance to strengthen the gluteal and hip muscles without undue impact. Another beneficial exercise involves slow, controlled knee-to-chest lifts while floating or holding the wall, which helps to increase flexibility in the hips and lower back. These exercises mimic movements used in formal aquatic physical therapy, which is an excellent option for structured, professionally guided rehabilitation.