Not exact matches
One study found that subjects that were doing a very hard
aerobic activity had significantly decreased glutathione levels that are
capable of affecting the gastrointestinal, nervous and immune
systems.
This is because the
aerobic system can just keep revving up over a pretty long period of time — as the carb levels in your muscles drop, your body may increase your fat - burning (if it's
capable of doing so)
The «problem» is that the energy
system capable of providing the endurance necessary for you to run marathons — which we call the
aerobic system — takes a very long time to develop.
While a lot of people's mitochondria are pretty
capable, eating a lot of sugar / carbs means that the second part of the
aerobic system is often underdeveloped.