High knees are a dynamic, plyometric exercise used in warm-ups and high-intensity interval training (HIIT) circuits to quickly elevate the heart rate. This bodyweight movement exaggerates the running motion by actively driving the knees upward toward the chest. The exercise is a closed-chain, weight-bearing activity that provides cardiovascular benefits while engaging numerous muscle groups simultaneously. It requires no equipment, offering an accessible method to boost aerobic fitness and prepare the body for more complex activities.
Step-by-Step Guide to Proper Form
Proper execution begins with standing tall, feet hip-width apart, and the core muscles braced to maintain a stable, upright torso. Your arms should be bent at approximately a 90-degree angle, positioned at your sides, similar to a sprinter’s ready stance. The movement is initiated by quickly and alternately driving one knee upward toward the ceiling, aiming to bring the thigh to at least a parallel position with the floor or hip height.
As one knee drives up, the opposite arm should simultaneously pump forward, mirroring the natural mechanics of running to aid momentum and balance. This synchronized, contralateral movement—right knee with left arm, left knee with right arm—is crucial for maximizing coordination and efficiency. The focus should be on a quick, explosive hip flexion to lift the leg, rather than simply pulling the foot up with the hamstring.
During the repetition, the foot of the lifted leg should descend rapidly, with the landing occurring lightly on the ball of the foot, not the heel. This forefoot landing helps to absorb impact and immediately prepares the foot for the next explosive push-off, minimizing ground contact time.
The entire movement should feel spring-like and aerobic, where the quick transfer of weight from one foot to the other generates the intensity. Maintaining a slight forward lean from the ankles, not the waist, can help keep the momentum flowing and prevent leaning back, which can strain the lower back. The speed and height of the knee lift can be gradually increased as coordination and endurance improve, but form should never be compromised for pace.
Muscles Activated During High Knees
High knees primarily target the muscles of the lower body and the core. The hip flexors (psoas and iliacus) are the main movers, responsible for lifting the thigh toward the torso. The quadriceps also contribute by extending the leg during the upward drive.
The posterior chain muscles, including the glutes and hamstrings, engage explosively when driving the foot down to the ground and providing power for the next lift. Calves are activated during the continuous push-off and landing phases, as the body remains on the balls of the feet. Core muscles (transverse abdominis and obliques) contract isometrically to stabilize the trunk and pelvis, preventing unwanted rotation or arching in the lower back.
Common Form Mistakes and Corrections
A frequent error is leaning too far forward or backward, which compromises spinal alignment and reduces the hip flexors’ ability to contract fully. The correction involves engaging the core and keeping the torso upright, maintaining a slight forward lean only from the ankles.
Another mistake is stomping or landing heavily on the heels, which sends unnecessary impact through the joints. To fix this, focus on landing softly and quietly on the forefoot, aiming for minimal noise. This technique utilizes the natural spring of the calf muscles and Achilles tendon for shock absorption and quick rebound.
Failing to lift the knee high enough limits the range of motion and diminishes the exercise’s benefits. The proper adjustment is to use the hands as a target by holding them out in front of the hips at waist level, consciously driving the knees up to meet them.
A final error is neglecting the arms, either by letting them hang loose or swinging them across the body. Proper arm drive is integral to balance and momentum. The correction is to pump the arms rhythmically in opposition to the legs, keeping the elbows bent and moving them forward and backward.