Exercises to Lessen Extensor Lag of Quadriceps

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Extension lag of the quadriceps typically occurs after injury or surgery on the knee joint. It is defined as lack of active knee extension with full passive motion available. That means that your knee can be stretched or will passively have normal range of motion, but you have insufficient quadriceps strength to achieve full extension with a muscle contraction. According to "The Journal of Orthopaedic and Sports Physical Therapy," extensor lag can be attributed to muscle weakness, joint stiffness and pain. Quadriceps weakness can be improved with a variety of exercises.

Step-ups are ideal for training quadriceps muscles for extensor lag because they focus on gaining terminal knee extension. To complete, stand at the bottom of the stairs, use a handrail or the wall for balance. Place your right leg on the bottom stair, and push up lifting your left leg off the floor as if you are climbing stairs. Let your left leg hang in the air and push your right knee straight focusing on gaining full knee extension. Hold this position for 10 seconds and slowly lower the left leg to the floor. This exercise can be done facing forward, sideways and backward going up the stairs. Always put your affected limb on the stair and push with that leg.

Seated Knee Extension

Rehabilitation by a trainer

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Seated knee extension exercises can be completed at home in a chair or on a weight training machine at the gym. If you are using weights, it is important to monitor your technique and ensure you are able to maximally extend your knee. Sit with your feet on the floor and slowly raise your affected leg until your knee is straight. Hold it straight at maximum extension for 10 seconds and slowly lower to the floor.


General squats and lunges can also assist with improving quad strength but you may see better results by training at end range knee extension with the above exercises. General exercise guidelines for strength training are to complete eight to 10 repetitions for three sets. Advance resistance when the exercise becomes easy. To continue to gain strength, you must work the muscle to fatigue. With these exercises, it is important to focus on end range quadriceps motion. Proper technique is crucial to training the quadriceps at end range.

Electrical Stimulation

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A study in 2009 in "The Journal of Medical Biomechanics" reported that use of electrical stimulation coupled with traditional exercise resulted in more improvement of extensor lag than traditional exercise alone. If you aren’t seeing sufficient improvements on your own, try a physical therapy program that can incorporate the use of electrical stimulation.