The underhand pull-up (chin-up) is a classic exercise. For most trainees it can rank as an effective pulling movement, though probably not as well as the row. It requires a specific style of performance though, and even then it it suboptimal.
The underhand pull-up works the upper back, the back half of the shoulders, and the elbow flexors. Major muscles include the latissimus dorsi, teres major, trapezius, rhomboids, rear deltoid, biceps brachii, brachioradialis, and brachialis. Joint motions include shoulder extension and adduction, scapular adduction or retraction, and elbow flexion.
Although not mentioned in most sources, with the proper form it also addresses the back half of the middle deltoid. Since the shoulder depresses as well (not as much with the style suggested), the sternal portion of the pectoralis major, pectoralis minor, and subclavius receive work as well. The abdominals stabilize and contribute to the movement intensely through a natural but slight crunch. It co-contracts with the latissimus dorsi. The muscles attached to the hands and forearm work hard to maintain the grip.
This guide focuses on the underhand pull-up using an overhead bar. Usually a chin-up refers to a supinated hand position. A pull-up refers to a pronated hand position. I use pull-up instead of chin-up here.
You will need an overhead bar. Use a box for elevation if needed. I suggest against jumping. An overhead bar can aggravate the wrists, due to the extreme supination required. A V-shaped bar would be ideal. This allows you to assume a moderate grip between supinated and neutral. Gymnastics rings, if available, represent a challenging variation that can match joint function as well. Although an Olympic bar can wedge in the saddles of a power rack as a substitute, this may prevent the stability needed. For assistance if needed, bands that assist with your bodyweight can help. These modify the resistance curve for the exercise though, so do not use them unless necessary.
The ideal pulling movement is horizontal. This best protects the joints and works the involved muscles at their ideal lengths for generating tension. In theory, the row would function as the best option. It should surpass the pull-up. Unfortunately, rows allow poor adjustments in body position too easily as the weight increases. It becomes effortless to cheat the weight up, reducing the range of motion needed. The pull-up is a vertical pulling exercise that elevates the arms. This is undesirable. This can cause joint stress and work the muscles poorly as commonly performed. With the right setup though, these effects are minimized. This involves setting the body in a lean-back position.
Use a standard medium grip to grab the bar. The arm should place at about a 45° relative to the body with this grip. When the humerus (arm bone) abducts and externally rotates, it tends to close up the space under the acromion. This occurs with a wide, overhand grip. The glenoid becomes packed, making impingement of rotator cuff likely. This method came from bodybuilding to isolate the upper back muscles and limit arm involvement. Instead, you gain a less functional exercise while risking joint injury. Isolation is a flawed concept.
Conduct this test to determine grip width: elevate the arms with the palms facing the ceiling. Begin at your sides. If the hands remain too close together, you will not be able to meet the bar with your hands. The tightness in your shoulder will stop you about halfway up. Too wide will strain the wrists and feel unnatural. The medium grip will keep the elbows in line with the wrist as well.
Keep the shoulder blades pulled back and down away from your ears. Stick the chest out. Maintain this tight position throughout the exercise and never allow slack. Lean slightly backward at the pelvis and low back. This may make the movement feel harder due to poorer leverage, but works the muscles better. Although mechanically during pulling movements the resistance should move in a straight path close to the body, assuming the proper position will increase the distance between your body and the bar. Better leverage and hence using more weight does not always stimulate muscles best. Keep your eyes focused toward the ceiling or where the wall meets the ceiling. This assists in maintaining the setup.
Some include a hip-initiated movement referred to as a kip. This can only really occur if using a grip other than that recommended in this article. I would recommend against it anyway, though this is a mute point. The body moving through space prevents most cheating. This makes the intended muscles perform the work. Grab the bar tightly. Maintain retraction and depression of the shoulder blades. Lift your feet from the ground to start the motion.
Lifting (Positive) Phase:
Keep the elbows in front of the body. Avoid attempting to draw them behind the body. Although this motion is impossible, the attempt to do so can harm the joints. Drive the elbows downward to propel yourself away from the ground. Use all the involved joints to elevate your body. Do not try to focus on a single joint action. Make the endpoint at the top of the movement with your chin just above the bar. Any additional range of motion is unnecessary. With the proper setup, this endpoint will feel harder to achieve than if depressing the shoulders without the lean-back position. Squeeze the butt to limit swaying.
Lowering (Negative) Phase:
Do not drop and control your bodyweight, but move quickly. Do not forcefully lock out the elbows at the conclusion of the repetition while lowering. Attempt to keep a slight bend in your elbow if the lockout causes stress. Keep using the same tips recommended in the lifting phase. Stay tight with the lean-back posture.
Slowly lower yourself to the bottom and let go of the bar with your feet close to the ground.
The Underhand Pull-Up
The pull-up serves as a possible pulling movement. Sometimes referred to as the upper body squat, it works many muscles simultaneously and intensely throughout the upper body and core. The row remains the superior choice though due to less stress on the shoulder and more ideal length-tension relationships in the muscles.