• Overweight and obese older adults exhibit significantly lower patellofemoral joint force and contact area during normal walking compared to normal-weight individuals.
• During Tai Chi movements, knee flexion moment, patellofemoral joint force, and quadriceps muscle force are significantly reduced in overweight and obese groups.
• Body mass index is negatively correlated with several patellofemoral joint biomechanical parameters during specific Tai Chi movements, indicating reduced joint loading with higher BMI.
• Tai Chi is recommended as a safe exercise for overweight and obese older adults to minimize lower limb joint loading and prevent injuries.