The heel slide, also known as the supine knee flexion and extension exercise, is a foundational movement in physical therapy for individuals recovering from knee or hip injuries and surgeries. This simple, low-impact exercise gently mobilizes the knee joint to restore range of motion, particularly knee bending (flexion). Moving the heel along a surface allows for controlled muscle activation and joint movement without placing excessive stress or bearing weight on the limb.
Executing the Basic Heel Slide
To begin the exercise, lie flat on your back on a firm surface, such as a mat or the floor, with both legs extended straight out. Placing a small towel, plastic bag, or sock under the heel of the affected leg will significantly reduce friction. The non-exercising leg can remain straight or be bent with the foot flat on the floor for comfort.
The movement starts by slowly bending the knee of the affected leg, actively sliding the heel backward along the surface toward the buttocks. This action primarily engages the hip flexor and hamstring muscles to pull the limb into flexion. Continue the slide only until a gentle stretch is felt at the knee or hip joint, which is the comfortable limit of the current range of motion.
Maintain this maximum bent position for a brief hold of three to five seconds. Following the hold, slowly and with control, push the heel back to the starting position until the leg is fully extended. The entire movement should be performed slowly to prevent jerky motions and maintain continuous contact between the heel and the surface. A typical routine involves completing 8 to 12 repetitions for one set, suggesting two to three sets performed daily.
Identifying and Correcting Common Form Errors
One frequent error is lifting the heel or the entire leg off the ground during the movement, which defeats the purpose of the slide. The heel must remain in contact with the surface throughout the entire range of motion to ensure a controlled, isolated movement of the knee joint. If the heel lifts, slow the movement down and actively press the heel into the surface, using less force to pull the leg.
Another common mistake is pushing through sharp or severe pain in an attempt to gain more range of motion quickly. While a mild, tolerable stretch or discomfort is expected, sharp pain indicates that the joint or surrounding tissues are being irritated or strained. If this occurs, immediately reduce the distance the heel slides backward and only move within the current comfortable limit.
Compensating with the torso is a third error, often seen as arching the lower back or twisting the hips. This compensation reduces the therapeutic benefit to the knee and can place unwanted strain on the lower back. The correction involves ensuring the back and hips remain level and pressed gently into the floor throughout the slide. Maintaining the foot, knee, and hip in a straight line, without allowing the foot to rotate inward or outward, prevents unnecessary twisting in the joint.
Modifying the Exercise for Progression
As mobility improves and the basic slide becomes easier, the exercise can be modified to continue challenging the joint and surrounding musculature. A simple progression involves incorporating a strap, belt, or towel looped around the foot for an assisted pull to increase knee flexion. After actively sliding the heel as far as possible, gently pull on the strap to encourage the knee to bend a fraction further, holding the deeper stretch for five to ten seconds.
Another way to advance the exercise is to add resistance by performing the slide on a surface with slightly more friction, such as a thin carpet instead of a polished floor. This requires the muscles to work harder against the resistance to pull the heel back. For an advanced core challenge, the “heel slide with a hover” involves lifting the heel one to two inches off the surface during the extension phase, requiring greater engagement of the abdominal muscles to stabilize the hip.
Progression guidelines often suggest increasing the number of repetitions or sets, but the most important indicator for increasing difficulty is the ease of movement and the absence of pain. Once the current range of motion is achieved easily and without discomfort, introduce one of these modifications. Remember to consult a therapist or physician before advancing the routine to ensure the progression is appropriate for the stage of recovery.