More formally, chiroplasty, or cheiroplasty, is a term which refers to plastic surgery of the hands. The term combines root word chir(o), which means hand, and the suffix -plasty, which means surgical repair.
(How Do Your Muscles Work continued) Thousands of thin spaghetti-like fibers make up muscle tissue. These fibers receive messages from the brain, causing the fibers to contract. The main muscles at work in cycling are the quadriceps and hamstrings in the upper leg, and the gastrocnemius and soleus in the calf. These muscles contract in a sequence that creates the pedaling action. The quadriceps and hamstrings do most of the work when you ride a bicycle.
Elite cyclists are born, or made, but the very best are probably both. Cyclists create power by mixing food energy with oxygen at a certain rate, just as cars create power by mixing fuel (petrol, gasoline) energy with oxygen. In both cases the speed with which oxygen can be mixed with energy is the limiting factor in power output, not the supply of food or fuel which is almost limitless.