Purpose: This study aimed to investigate the changes in pain following exercise sessions with different intensities in patients who underwent total knee arthroplasty (TKA). Methods: This is a repeated measure and single-blinded randomized controlled study. Thirty-six patients who underwent TKA (age, 64.9 ± 7.42 years) were randomly assigned to either low-intensity exercises (LIEs) group or high-intensity exercises (HIEs) group. Exercise programs lasted for five days during the hospitalization period. Pain intensity was assessed by visual analog scale (VAS) and pressure pain thresholds (PPTs) were measured over quadriceps and biceps brachii and muscles immediately before and after exercise. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) subscale (pain, stiffness, and physical function) scores were recorded at two points in baseline and discharge from the hospital. Results: The pain intensity decreased in patients in both groups after TKA. PPTs increased in both groups at all tested sites following the first, third, and fifth exercise bouts. HIE program had a greater positive effect on the pain intensity after the first exercise session than LIE program on the PPTs (<FOR VERIFICATION>p < 0.05). HIE program was more effective in order to reduce pain severity immediately after the exercise sessions in patients (<FOR VERIFICATION>d: 0.5, <FOR VERIFICATION>p < 0.05). WOMAC scores significantly improved in both groups during the discharge from the hospital (<FOR VERIFICATION>p = 0.001). Conclusion: Our results found that both LIE and HIE programs performed during hospitalization after TKA declined pain intensity. Particularly notable were the substantial improvements observed in managing post-operative pain, especially following the second exercise session. The HIE program proved more effective in improving stiffness, and enhancing physical function.