Food and Energy
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
How hard you work during exercise
because our body system has to work harder
perceived exertion
Mitochondria make the energy in your body. During exercise you need more energy so you need more energy "factories"
Yes, however during intense opiate withdrawls (first 3-5 days depending on habit) it will be pretty hard to force exercise on the body. Exercise really helped me out with coping with the withdrawals from opiates. My 'restless leg' problem was also gone when I took to running at just about the time when my pangs set in. I was addicted to Dextropropoxyphene for over 15 years. Trust me, vigorous exercising really works !
Hard exercise on a water fast is a seriously bad idea. Your body will have to find the energy somewhere, and if you aren't eating there aren't many places it can get it from. Muscle is easier to metabolize than fat, so they will suffer.
A person who wants to exercise safely without endangering their health should use a heart monitor. They can do this by monitoring how hard their heart works before, during, and after workouts.
white blood cell
Because your body cells, especially the ones that are working hard, need more oxygen to burn the fuel to keep on exercising.
Her butt is real, her boobs aren't, she works out hard to achieve her body though
you get hard