High knees are a popular exercise often used to warm up for more intense activity. While the exercise is a powerful agent for strengthening specific muscle groups, it does not involve the static, held positions traditionally associated with stretching. Instead, high knees are a dynamic movement that rapidly and repeatedly contracts and lengthens muscles, preparing the body for performance.
High Knees as Dynamic Movement
The high knees exercise is a form of dynamic stretching or movement preparation, which involves active, controlled motion through a joint’s full range of motion. This continuous motion increases blood flow and muscle temperature, making tissues more pliable and ready for work. Execution involves alternating the legs to drive the knees up toward the chest, ideally reaching above the level of the hips, while maintaining an upright posture. The explosive, repetitive nature of the movement exaggerates the running gait, training the body to move with greater efficiency and range.
Key Muscles Targeted During Lift
The primary muscles responsible for the powerful lifting action of the knee are the hip flexors, a group of muscles including the iliopsoas. The iliopsoas, composed of the psoas major and the iliacus, works to pull the thigh and knee toward the torso. High knees demand high activation of these hip flexors as they concentrically contract to bring the knee up past the typical 90-degree angle of walking. Strengthening these muscles is particularly important for activities like running and jumping, where a strong upward pull of the leg is necessary for speed and efficient stride.
The quadriceps, especially the rectus femoris, also play a significant role in the lift, assisting the hip flexors in the upward movement and extending the knee. This action provides a rapid, cyclical engagement of the muscles on the front of the thigh and hip, improving both their strength and their ability to operate quickly. The calves are also engaged with each step, as the foot typically lands and pushes off from the ball of the foot, which strengthens the forefoot and toe muscles important for balance.
Stabilizing the Trunk and Lower Body
Beyond the powerful lifting muscles, the high knees drill heavily recruits several muscle groups to maintain balance and control throughout the movement. The core muscles, including the abdominals and obliques, stabilize the trunk and prevent the torso from swaying side-to-side or rounding the back. Maintaining an upright posture requires a constant, isometric contraction of these muscles to provide a stable base for the alternating leg action. This stabilization is necessary for transferring force efficiently and reducing the risk of undue strain on the lower back.
The glutes and hamstrings are also active, though their role is primarily in the stance phase and in controlling the descent of the leg. As the lifted leg returns to the ground, the hamstrings and glutes on the landing side work to decelerate the limb and absorb the impact. Meanwhile, the glutes on the grounded leg must fire to stabilize the hip and pelvis, preventing excessive movement while the opposite leg is in mid-air. This continuous stabilization from the core and posterior chain is what makes high knees a full-body conditioning exercise.
Preparing the Body for Performance
The functional application of the high knees exercise is best understood in its role as a warm-up drill, preparing the body for more demanding activities like sprinting or plyometrics. The rapid, alternating motion quickly elevates the heart rate and increases blood flow, which raises the temperature of the muscles. This physical preparation enhances dynamic flexibility and joint mobility, ensuring the hips and knees can move through a full range of motion without restriction.
A less obvious, yet equally important, benefit is the activation of the central nervous system (CNS). The quick, coordinated movements of high knees, combined with the arm pump, help to prime the body’s motor units and improve neuromuscular efficiency. This “waking up” of the nervous system improves coordination and reaction time, making the body more responsive and reducing the risk of injury during subsequent athletic performance. By exaggerating the running form, high knees also serve as a skill-development exercise, helping to ingrain the movement patterns required for a more powerful and efficient running technique.