Objective <p>To compare the effects of different intensities of resistance training on self-reported lymphedema symptoms, upper limb muscle mass, and quality of life in patients after breast cancer surgery.</p> Methods <p>A total of 114 breast cancer patients who underwent axillary lymph node dissection were randomly assigned to three groups: control group (standard care), Intervention Group 1 (standard care plus low-intensity resistance exercise), and Intervention Group 2 (conventional care plus moderate-to-high intensity resistance exercise). Assessments were conducted at baseline, post-intervention, 3-month follow-up, and 6-month follow-up. Primary outcomes included patient-reported lymphedema symptoms (pain, swelling, tightness); secondary outcomes comprised bilateral upper limb skeletal muscle mass and quality of life.</p> Results <p>Before intervention, there were no statistically significant differences among the three groups in terms of lymphedema symptoms, skeletal muscle mass in both upper limbs, and quality of life (<i>P</i> &gt; 0.05). After intervention and at the 3-month and 6-month follow-ups, both Intervention Group 1 and Intervention Group 2 demonstrated significant improvements in lymphedema symptoms, skeletal muscle mass in both upper limbs, and quality of life compared to the control group (<i>P</i> &lt; 0.05). Furthermore, the improvement in tightness sensation in the affected limb, skeletal muscle mass in both upper limbs, and total quality of life score was significantly greater in Intervention Group 2 than in Intervention Group 1 (<i>P</i> &lt; 0.05).</p> Conclusion <p>Resistance training effectively improves lymphedema symptoms in breast cancer patients post-surgery, increases upper limb muscle strength, and enhances quality of life, with moderate-to-high intensity training yielding superior outcomes.</p>