To avoid any danger of injury it is absolutely recommended to do warm-up exercises. The stretching of the Achilles tendon is ideal before doing leg exercises. For that, make a little lunge forward and flex slightly your leg while you stretch backward the other leg. To make sure that the exercise is effective, the heel of your backward leg should not fully touch the ground. Keep your arms stretched and close to your head. Remain in this stretched position for 15 seconds and repeat the exercise with the other leg.