The fitness world often uses a straightforward classification system to structure workouts, dividing movements into “push” or “pull” categories. This organization simplifies programming by grouping muscles that work together, such as the chest and triceps for pushing, or the back and biceps for pulling. While this system works seamlessly for the upper body, its application to the lower body often causes confusion, particularly regarding the quadriceps. Understanding where the quads fit requires looking beyond routine names and into the actual biomechanics of the movement.
The Primary Function of the Quadriceps
The quadriceps femoris, commonly called the quads, is a large muscle group consisting of four distinct muscles situated on the front of the thigh. These four heads include the Rectus Femoris, Vastus Lateralis, Vastus Medialis, and Vastus Intermedius. Collectively, the primary action of the quadriceps is knee extension, which is the movement of straightening the leg from a bent position. This force is transmitted through the tendons to the tibia, enabling fundamental movements like standing up, walking, and jumping.
The Rectus Femoris is unique among the four muscles because it is the only one that crosses both the knee and hip joints. This anatomical position gives it a secondary function: it assists in hip flexion, which is the action of raising the thigh toward the torso. However, in most compound lower body movements, the force generated by the quadriceps is directed toward extending the knee, making them the sole extensor muscle of that joint.
Classifying Quad Exercises as “Push”
The classification of an exercise as “push” or “pull” is based on the direction of the force relative to the body or the ground. A push movement drives resistance away from the body, or pushes the body away from the resistance. Conversely, a pull movement draws weight or resistance toward the body. Since the quadriceps’ main role is knee extension—the act of straightening the leg—their exercises fit squarely into the biomechanical definition of a push.
When performing a squat or a leg press, the quads contract to push the body or the sled away from the floor or machine, resulting in knee joint extension. Even isolation movements like the leg extension machine are push exercises, as the quads push the lower leg and the weight pad away from the thigh. The force generated by the muscle projects the resistance outward, fulfilling the criteria for a push movement. Therefore, based on their mechanical action of straightening the leg, the quadriceps are a push muscle group.
Why Legs Are Categorized Separately in Training Splits
Despite the quads being mechanically a push muscle, most common strength training routines, such as the Push/Pull/Legs (PPL) split, dedicate a separate day to the lower body. This split exists due to training efficiency, recovery needs, and the mixed nature of lower body actions. Leg day groups together all major muscles below the waist, including those that perform both pushing and pulling movements.
While the quads are the primary push muscles, the hamstrings and glutes perform biomechanically categorized pull movements. For example, the hamstrings pull the weight or the lower leg toward the body during curls or deadlifts. Combining all lower body work allows for a high-volume session focused on movements like squats without fatiguing the upper-body muscles needed for push or pull days. This grouping optimizes the weekly schedule by managing the recovery demands of the large leg muscles.