Why does my leg shake when i lift my heel?
Answers
It's part of the Golgi tendon reflex. Golgi tendons are small receptors located in every muscle that protect them from over stretching damage. They do this by recognising when a muscle is over stretched and then sending a message to your spinal cord- which then sends a message back telling the muscle to contract to prevent it hurting itself.
When you go onto your tiptoes the Golgi tendons sense the calf (gastrocnemius, soleus and to a lesser degree plantar is) is stretching, so the it sends the message to the spinal cord and we get the contraction reflex. So then the leg rises due to plantar flexion at the ankle and the calf muscles relax. After they relax, the leg drops again- we get the stretch- then the stretch reflex and the cycle repeats, carrying on the continual bounce of the leg