Knee bursitis is the inflammation of a bursa, a small, fluid-filled sac that cushions bones, tendons, and muscles near a joint. When the bursa, such as the prepatellar (over the kneecap) or infrapatellar (below the kneecap) bursa, becomes irritated, it swells with excess fluid, causing pain and tenderness. While the condition limits activity, exercising with knee bursitis is possible, depending entirely on the current stage of inflammation. Safe physical activity shifts significantly between the acute, painful phase and the subacute recovery phase.
When Rest is Non-Negotiable
Exercise must stop immediately during the acute phase of knee bursitis to prevent further irritation and worsening of the condition. Pushing through the pain prolongs recovery and increases the risk of chronic inflammation. Signs signaling the need for complete rest are severe, constant pain and rapid, noticeable swelling directly over the knee.
Specific signs of acute inflammation include tenderness and warmth to the touch around the affected bursa. Any motion causing sharp pain or significantly limiting the knee’s range of motion requires immediate rest and potentially medical consultation.
The presence of systemic symptoms indicates septic bursitis, which is an infection of the bursa. If you experience fever, chills, spreading redness, or an inability to move the affected joint, seek medical attention urgently. Septic bursitis requires specific medical treatment, such as antibiotics, to prevent the infection from spreading. Ignoring these warning signs can lead to serious complications and long-term mobility issues.
Safe Low-Impact Activities for Recovery
Once acute pain, warmth, and swelling subside, the focus shifts to maintaining muscle function through safe, low-impact exercises. The goal is to encourage blood flow for healing and prevent muscle atrophy without placing direct pressure or excessive friction on the bursa. These movements must be performed within a pain-free range of motion; any increase in discomfort signals the need to stop immediately.
Gentle isometric exercises are a starting point because they activate muscles without moving the joint, minimizing bursa irritation. A quad set involves tightening the thigh muscles by pressing the back of the knee down onto a towel roll for a few seconds. This action helps maintain quadriceps strength for knee stability without causing joint movement.
Straight leg raises are excellent for strengthening the quadriceps and hip flexors while keeping knee movement minimal. While lying down, the straight leg is lifted slowly about a foot off the ground, engaging the muscles for stability. This controlled motion prevents repetitive friction that could aggravate the inflamed bursa.
Cardiovascular fitness can be maintained safely with activities that eliminate impact and deep knee bending. Stationary cycling, set with a high seat and very low resistance, allows for a smooth, controlled range of motion. The high seat height minimizes knee flexion, preventing compression of the bursa.
Water-based exercise, such as pool walking, is highly beneficial because water buoyancy reduces the body weight load on the knee joint. Gentle water aerobics or swimming are also good options, provided kicking motions are kept minimal or avoided completely. These low-resistance movements improve circulation and mobility, accelerating healing in a protected environment.
Identifying High-Risk Movements and Modification
As the knee recovers, identify and avoid or modify movements that place stress, friction, or direct compression on the bursa. Exercises requiring deep knee flexion or involving high impact are the biggest offenders and must be managed carefully. The primary mechanism of injury is the excessive force or pressure that physically squashes or rubs the inflamed sac.
Deep squatting and lunges are high-risk because bending the knee past a 45-to-60-degree angle significantly increases compressive forces on the joint and surrounding bursae. A safer alternative for strength training is to perform partial squats, limiting the depth to a pain-free range. Wall sits or chair squats, where the range of motion is controlled, also provide a safer way to build lower body strength.
Activities involving repetitive impact, such as running, jogging, and high-impact aerobics, should be substituted with lower-impact alternatives. The jarring force of striking the ground creates stress that can easily re-injure the bursa. Using an elliptical machine or brisk walking on a flat surface significantly reduces the repetitive shock load compared to running.
Kneeling, a common cause of prepatellar bursitis, must be strictly avoided during recovery as it places direct, sustained pressure on the bursa. Any activity involving bearing weight on the knee, such as certain yoga or floor exercises, should be eliminated until full recovery. High-resistance exercises on machines like leg extensions or leg presses should also be avoided or performed with very light weight and limited movement, as they generate high shear forces.