Is it normal for the arms to be different in size when exercising

It is usually normal for the arms to be thicker during exercise, and in most cases, it is related to the habit of exerting force and asymmetrical movement patterns. In rare cases, it may indicate muscle damage or abnormal nerve innervation. The difference in arm circumference between the two sides during fitness is common in individuals with unilateral advantage, such as right-handed individuals who have more developed muscles on the right side. In daily training, exercises such as pushing and pulling can easily lead to uneven muscle growth due to excessive force exerted by the dominant hand. Pay attention to adjusting posture symmetry during training, increase individual training on the weaker side, and use dumbbells instead of barbells to reduce compensation. If the difference persists for more than 2 centimeters after 3-6 months of observation, it is recommended to undergo a posture assessment. Pathological asymmetry should consider brachial plexus nerve injury or muscle strain, which may be accompanied by symptoms such as force pain and limited joint movement. Cervical spondylotic myelopathy may lead to unilateral upper limb muscle atrophy, and electromyography examination can clarify the nerve conduction status. Unilateral swelling after trauma requires examination for hematoma or compartment syndrome, which often accompanies changes in skin temperature and significant tenderness.

It is recommended to regularly measure the circumference of both arms and record changes. During training, mirror observation or video recording should be used to correct movement deviations. Ensure a protein intake of at least 1.6 grams per kilogram of body weight through diet, and conduct 1-2 additional targeted training sessions on the weaker side after training. If accompanied by neurological symptoms such as numbness, stabbing pain, or persistent pain, one should promptly seek medical attention from a rehabilitation medicine department to investigate organic problems.