Low-intensity Kaatsu resistance training performed by patients with moderate vascular occlusion is known to cause skeletal muscle hypertrophy over a short term. In our patients who used such training as a part of their rehabilitation, we have seen the same results, as well as a quenching analgesic effect. Herein, we report the effect of Kaatsu resistance training in a patient with patella tendinitis. The patient was a 17-year-old male who played basketball and came to us with intense pain at the lower edge of the patella in the right knee and was confirmed by an MRI image which showed a high intensity signal in the area of the patella tendon. Initially, we gave a dose of antiphlogistic analgetic, a steroid injection, and prescribed hospitalization for 1 month. Kaatsu resistance training was also recommended in an attempt to prevent muscle atrophy. The vascular occlusion point for the Kaatsu training cuff was the proximal end of the right limb, which had an occlusion pressure ranging from 160-180 mmHg. The exercise components that were used in combination with the Kaatsu training program were SLR, hip abduction, hip adduction, calf raise, toe raise, squat, crunch, back extension, and shooting. The exercise protocol was performed at about 30% of 1RM, with 3 sets of 15 repetitions, 5 to 6 times per week, for 3 weeks. T2 weighted MRI images (axial and sagittal) of the right patella tendon prior to beginning Kaatsu training showed high intensity signals, however, after 3 weeks of Kaatsu training, the signal intensity was reduced and the thigh circumference was increased by 7 mm and 2 mm for the right and left sides, respectively. Further, there was no evidence of muscle atrophy. The present patient was then treated with appropriate anti-inflammatory drugs and 1-month of hospitalization. During that time it was possible to completely relieve the inflammation and avoid muscle atrophy with Kaatsu training, and the patient quickly returned to playing basketball. In conclusion, this low-intensity resistance training was able to be performed without applying excessive load, which may have caused further damage, and we intend to use Kaatsu training with future patients to help them return as early as possible to full activities.