There are 3 energy systems that runners have to be aware of and each system has to be trained a specific way.
The 3 energy systems:
ATP – PC (Adenosine Triphosphate Phosphocreatine) or referred to as the Power system (phosphagen) (non-oxygen dependent) (without oxygen) . Running events lasting 10-30 sec.
Glycolytic system (anaerobic) (non-oxygen dependent) (without oxygen) (dependent on muscle glycogen) (stored carbohydrates). Running events lasting 1-2 min.
Aerobic or Oxidative system (oxygen dependent) (with oxygen). Running events lasting several minutes to hours.