OBJECTIVE: To investigate the efficacy of 4 weeks of preoperative and 4 weeks of postoperative progressive resistance training (PRT), compared to 4 weeks of postoperative PRT only on functional performance, muscle strength, and patient-reported outcomes in patients undergoing total knee arthroplasty (TKA). METHODS: In total, 59 patients were randomized to 4 weeks of preoperative PRT (intervention group) or to a group who lived as usual (control group). Both groups performed 4 weeks of PRT after TKA. At 6 weeks and 1 week before TKA, and at 1, 6, and 12 weeks after TKA, performance-based measures (30-second chair stand test [30sCST], timed-up-and-go [TUG], and walking tests), knee extensor and flexor muscle strength (dynamometry), patient-reported functional performance, health-related quality of life, and pain scores were evaluated. RESULTS: When comparing the changes from baseline to the primary test point 6 weeks after TKA, a significant group difference in favor of the intervention group was found for the 30sCST (2.5 repetitions [95% confidence interval (95% CI) 0.9, 4.1] versus -1.1 repetitions [95% CI -2.8, 0.7]; P < 0.004), the TUG (-0.7 seconds [95% CI -1.6, 0.1] versus 0.8 seconds [95% CI -0.1, 1.7]; P = 0.015), normalized knee extensor muscle strength (-0.2 Nm/kg [95% CI -0.3, -0.1] versus -0.4 Nm/kg [95% CI -0.5, -0.3]; P = 0.002), and normalized knee flexor muscle strength (0.1 Nm/kg [95% CI 0.0, 0.2] versus 0.0 Nm/kg [95% CI -0.1, 0.1]; P = 0.016). No differences were found between groups on patient-reported outcomes. CONCLUSION: Supervised preoperative PRT is an efficacious and safe intervention for improving postoperative functional performance and muscle strength, but improvements in patient-reported outcomes were not detected.