Chemical Energy.
Energy is stored as fat in the muscles.
In this case the player is compressing muscles in his legs which then can be expanded to produce kinetic energy. The energy stored in the muscles would be a form of elastic potential, but I don't think it is quite the same as winding up a rubber band, because the muscles actually produce energy as well as release stored energy. You might get a better explanation from section Human Physiology.
Food provides energy, and too much food = too much energy so it will be stored. It will be stored and it is what we call fat. Fat can be stored almost anywhere on the human body, their usually stored around our bellys, butts, legs and arms.
The primary energy reserve stored in the body is glycogen, which is stored in the liver and muscles. Additionally, the body can also store energy in the form of adipose tissue (body fat) for long-term energy storage.
Glucose is stored in the liver and muscles in the form of glycogen. When blood sugar levels are high, excess glucose is converted to glycogen for storage. This stored glycogen can be broken down back into glucose when needed for energy.
Potential energy is energy that is stored in an object due to its position or configuration. In the context of the human body, potential energy can be stored in the form of chemical energy in food or as mechanical energy in muscles, ready to be used when needed for activities like movement.
When you sweep the yard, your muscles use chemical energy stored in the form of adenosine triphosphate (ATP) to perform the physical work of sweeping. The muscles contract and relax, converting this chemical energy into mechanical energy to move the broom and complete the sweeping motion.
Adenosine Triphosphate (ATP)?
Excess nutrients are stored in the body as energy reserves in the form of glycogen in muscles and the liver, and as triglycerides in adipose tissue. These reserves can be used by the body when needed for energy production.
Energy stored in your muscles, which ultimately comes from the food you eat.
The body stores primary energy in the form of glycogen in the liver and muscles, and in adipose tissue in the form of triglycerides. When needed, these energy stores are broken down and converted into usable energy for the body.
Glycogen is stored in the cytosol of every cell, bound to water. The main store of glycogen in the human body is the liver. It is also stored, bound to water, in muscle cells where it provides a source of rapid energy during exercise.Glygcogen is a storage form for glucose which is found in the liver where it is formed from a glucose and from noncarbohydrate sources, such as amino acids and the glycerol portion of fats via gluconeogenesis. Another, and major glycogen store in terms of mass, is within skeletal muscles, where glycogen is stored so that there is a ready source of glucose for activity.