The body's fuel requirements become higher as the body's main energy source(carbohydrates) becomes depleted and needs topped up with a sugary substance.
or
The body's fuel may increase as you may not have enough glucose in your body so your body starts to break into your glycogen store's (fat, which is stored glucose) which provides the body with huge amounts of energy.
Eat alot.
by doing exercise
just one exercise can increase flexibility in a body and that is only all kind of physical exercise ,,
You can increase your muscles by doing regular exercise. gradually increasing resistance. following a proper diet and achieving proper rest...your muscles grow while resting not while working out....
you get dehydrated (lose body water) by doing lots of exercise or doing a tiring activity
lactic acid
Carbohydrate is a food stuff which is the bodies preferred fuel. Your body will choose to burn carbs first, except whilst doing aerobic exercise where it will choose to burn fat. Any carbs your body does not burn off through the day will be stored on the body as fat.
when we exercise more HDL cholesterol are being produced which reduces our body cholesterol
During exercise, your body uses energy. This process requires oxygen. So, if you exercise you pant, or breathe harder, in order for your body to draw in more oxygen.
Progressive Overload
you get dehydrated (lose body water) by doing lots of exercise or doing a tiring activity
Biking is a great exercise for cardiovascular. Biking is hard on the body in a good way in that it works the lower body but whilst it is good for cardio it can be bad for your joints so if you are looking for a cardio exercise which is not hard on your body you should try something like swimming