The aim of our experiment was to study the effects of physical activities on the biochemical and biomechanical properties of tendons in 12 standard (S) broilers and 12 Label Rouge (LR) chickens. In the two types of birds no differences were found between control and active birds for body weights. Gastrocnemius (Gas) tendon and Pectoralis minor (Pm) tendons were harvested and processed for passive stretch tests prior to cooking or not. Some biochemical parameters alsowere determined. Results showed that total collagen content in Gas tendon was significantly higher in active than in control birds. However, no significant changes were found in collagen solubility in LR tendons while these values were increased in S ones. Active birds showed greater sGAGs content than control ones. Ultimate load was found to be significantly higher in active birds than in control. Deformability (defined by Poisson’s ratio) of raw and heated at 80◦C Gas tendons increases in active groups because Poisson’s ratio decreases. Physical activities also increase the rigidity (defined by elastic modulus) of raw and heated at 80◦C Gas tendons because elastic modulos values increase. Physical activity was not able to modify stiffness or maximum stress values in raw or heated at 80◦C Gas tendons from broilers whereas these two parameters were found to be slightly higher in active group from LR chickens only in raw tendons. All the biomechanical results recorded in Pm tendons from both types of chickens were not significantly different between control and active birds. A significant correlation was found between the total collagen content and stiffness in Gas tendon from LR active birds.