The lateral raise, designed to build wider, stronger shoulders, involves lifting the arm away from the body to the side (abduction). Although simple, this movement often causes pain due to the shoulder joint’s highly mobile and complex nature. The extensive range of motion comes at the cost of inherent stability, making the joint susceptible to strain during resistance training. Understanding the biomechanical reasons behind this discomfort is the first step toward performing the exercise safely. This article explores why lateral raises can hurt and provides strategies to resolve the issue.
Why Lateral Raises Stress the Shoulder Joint
Discomfort during lateral raises often stems from the narrow subacromial space in the shoulder. This small area is located beneath the acromion (the bony “roof” of the shoulder blade) and above the head of the humerus (upper arm bone). This space contains soft tissues, including the supraspinatus tendon and the subacromial bursa.
When the arm is lifted out to the side, the greater tuberosity of the humerus approximates the acromion, minimizing the subacromial space. This reduction can compress the tissues within, a mechanism known as shoulder impingement. Repetitive compression under load leads to irritation and inflammation, often felt as a sharp or dull ache during the lift.
While the medial deltoid drives the movement, the smaller rotator cuff muscles provide crucial stabilization. The rotator cuff must keep the head of the humerus centered within the shoulder socket as the arm elevates. If the deltoid overpowers a weak rotator cuff, the humerus can migrate upward, further reducing the subacromial space and increasing impingement risk.
Correcting Common Form Errors
One of the most frequent causes of pain is using too much weight, which forces the body to recruit larger muscles outside of the shoulder. Excessive weight often leads to using momentum or swinging the body to initiate the lift, compromising control and placing undue stress on the joint capsule. Reducing the weight allows for a smoother, more controlled tempo, ensuring the medial deltoid is the primary muscle performing the work.
Another common error is raising the arms too high, specifically past the point where the elbow is parallel to the shoulder. Once the arm travels above this 90-degree angle, the emphasis shifts away from the deltoid and onto the upper trapezius muscles. Lifting too high significantly increases the compression in the subacromial space, making impingement almost inevitable.
Improper hand positioning, often called the “pouring the water bottle” mistake, significantly contributes to shoulder pain. This involves internally rotating the shoulder so the thumb points downward at the top of the movement. This internal rotation drives the greater tuberosity of the humerus directly into the acromion, increasing the potential for rotator cuff tendon impingement. The hand should remain in a neutral position, with the thumb slightly higher than the pinky finger, to maintain an open joint space.
Finally, many individuals initiate the movement by shrugging the shoulders upward, which recruits the upper trapezius instead of the deltoids. This shrugging action elevates the entire shoulder girdle, further reducing the space beneath the acromion. To avoid this, the movement should be led by the elbows, and the shoulder blades should be actively kept down and back throughout the entire range of motion.
Adjustments to Minimize Strain
When pain persists despite correcting basic form, modifying the exercise setup can help isolate the deltoid while bypassing painful movement mechanics. One effective adjustment is changing the plane of movement from directly out to the side to slightly forward, known as the scapular plane. Raising the dumbbells about 20 to 30 degrees in front of the torso aligns the movement more naturally with the shoulder blade’s anatomy, which is a safer position for the rotator cuff tendons.
Switching the type of resistance can also alleviate strain, such as moving from heavy dumbbells to resistance bands or a cable machine. Dumbbells provide maximum resistance when the arm is parallel to the floor, which is often the most painful point of impingement. Conversely, leaning away from a low cable machine alters the resistance curve, placing more tension on the deltoid at the beginning of the movement when the arm is strongest, and less at the top.
Another simple modification is performing the exercise with bent elbows, which shortens the lever arm and effectively reduces the torque placed on the shoulder joint. This allows the use of heavier resistance while lowering the overall strain on the shoulder capsule. If a specific point in the range of motion is painful, reducing the range by stopping well short of parallel can prevent the arm from entering the painful impingement arc.
Identifying Underlying Shoulder Issues
While form errors are the most common cause of pain, persistent or sharp discomfort may indicate a pre-existing injury requiring medical attention. Pain that remains constant outside of exercise, or is accompanied by clicking, catching, or significant weakness, should be considered a red flag. These symptoms suggest structural damage beyond simple muscle fatigue or poor technique.
Common underlying conditions exacerbated by lateral raises include rotator cuff tendonitis (inflammation of the shoulder tendons) or bicipital tendonitis. Impingement syndrome often results from underlying biomechanical issues, such as poor posture or muscle imbalances that cause the humerus to migrate within the joint. If pain continues for more than two weeks despite strict form correction and exercise modification, consulting a physical therapist or orthopedic specialist is advised for an accurate diagnosis.