Understanding how resistance exercises are classified is fundamental to designing an effective training program. Strength training movements are often grouped by the muscles they engage or the joints they move. A more functional system separates upper body movements into two categories: push and pull. This classification is based purely on the direction of force and the resulting joint action. Proper classification of movements like the bicep curl ensures a balanced workout routine.
Defining Pull and Push Movements
The difference between a push and a pull exercise is determined by the biomechanical action that moves the resistance. A push movement involves exerting force to move a weight or object away from the body, generally involving the extension of a limb joint. Examples include the bench press or the overhead press, where the weight is extended away from the body. These movements primarily engage the muscles on the front of the body, such as the chest, shoulders, and triceps.
Conversely, a pull movement involves exerting force to move a weight or object toward the body, or pulling the body toward a fixed object, which typically involves flexing a limb joint. Exercises like a pull-up or a bent-over row are classic examples. Pulling movements predominantly activate muscles on the back of the body, including the back, rear shoulders, and biceps. This directional distinction provides the framework for classifying resistance exercises.
The Classification of Curls
Based on the criteria of directional force, the standard bicep curl is classified as a pull exercise. When performing a curl, the weight is moved from a position near the hips toward the shoulder. This action shortens the distance between the hand and the shoulder joint, which is the defining characteristic of a pulling movement.
The movement pattern involves elbow flexion, where the angle of the elbow joint decreases as the forearm is drawn upward against the resistance. This flexion is the joint action responsible for drawing the weight toward the body, confirming its place in the pulling category. The direction of the resistance relative to the body is the sole determinant of this classification.
Muscles Engaged During the Movement
The physiological function of the muscles involved solidifies the curl’s classification as a pull movement. The primary muscle driving the bicep curl is the biceps brachii, located on the front of the upper arm, which acts as the agonist. During the lifting phase, the biceps brachii contracts concentrically, meaning the muscle fibers shorten to generate the force needed to pull the weight up.
This concentric contraction is directly responsible for the elbow flexion that brings the weight toward the body. The movement is also assisted by synergistic muscles, namely the brachialis and the brachioradialis, which help stabilize the joint and contribute to the pulling force. The subsequent lowering of the weight involves an eccentric contraction of these muscles to control the weight’s descent.
Applying This Knowledge to Workout Splits
Understanding the curl as a pull exercise has significant practical implications for structuring a workout routine, particularly when utilizing a Push/Pull/Legs (PPL) split. This popular training method organizes workouts by movement pattern to ensure opposing muscle groups are trained efficiently and allowed adequate recovery time. The PPL split typically dedicates separate days to pushing movements, pulling movements, and lower body exercises.
Because the bicep curl is a pull movement, it is logically included on the “Pull Day” alongside other back and bicep exercises like rows and lat pulldowns. This strategic grouping ensures that the biceps, already fatigued from compound pulling movements, receive their isolated training on the appropriate day. Conversely, this classification prevents the biceps from being worked on “Push Day,” ensuring that the pulling muscles can fully recover before their next dedicated session.