the shops
Z's you dont really need GCSE's to work there.
Muscles do is to command the bones to move and you need food and energy to move around.
When any function has to be performed by body , muscles use energy. It helps in doing work.
The same place they get it from when they're used to do work ... the chemical potential energy that's extracted from food you eat, and stored in your body until the brain and muscles need it.
Your body uses oxygen make energy, and muscles need energy to relax and contract, or flex. As you run, the demand for energy in your muscles increases, and so your lungs work harder to provide the oxygen your muscles are begging for. The result of higher demand for oxygen is faster deeper breaths.
muscles need food and oxegen to work
Muscles must work together because you need to move your body.
Human work converts chemical energy from food into mechanical energy through the contraction of muscles.
Muscles primarily use chemical energy stored in the form of adenosine triphosphate (ATP) to produce mechanical work. The chemical energy in ATP is converted into mechanical energy to enable muscle contraction and movement.
Muscles turn chemical energy into heat and work during contraction. Straight from the science book.
The byproduct of ATP when it makes muscles work is ADP and energy. They are not harmful in anyway.
In a simple answer, one could say they begin the chain reaction because they need energy in order to work. At the end of glycolosis, along with ATP comes lactic acid which affects the muscles. That is what causes soarness in the muscles after we exercise.