Energy absorbing capacity of rat tail tendon at various ages.

Fibres from tail tendons of male rats aged 1--18 months were stretched to breaking point by an 'Instron' tensile apparatus. The energy absorbed during stretching of the tendon was calculated. A sharp increase was found in the energy value during the first 6 months of postnatal life. The following components of this energy were also evaluated: (1) energy absorbed during the period of linear relationship between force and extension; (2) energy absorbed during the period of non-linear relationship. Both components showed rapid increases in value during the first 6 months after birth, after which they levelled off.