> but in order to accelerate, a deer goes anaerobic, while the man remains in an oxygenated jogging zone.<p>Anaerobic exercise is where you get close to red-lining your body's limits.<p>The Ironman is arguably one of the most difficult single-day athletic event an individual can participate in. Training for the Ironman (2.4 mile swim, 112 mile bike ride, 26.2 mile run) requires at least one year of up to 20 to 40 hrs of concentrated training every week. The whole point of the training is to build your body's endurance such that when you do the actual race you do not go anaerobic. Even the people winning the race in 9hr times do not venture into the anaerobic zone while racing. Once you go anaerobic (lactic acid), your ability to complete the race (or even continue) goes seriously downhill. Going anaerobic is also the reason why most people cannot swim more than 100m without training (simply put - their technique is so bad that most of their energy is expended and wasted into fighting the water - so it's like running 100m sprints).<p>Also, check out the Marathon Monks of Japan. 84km/day for 100 days.<p><a href="http://www.howtobefit.com/tendai-marathon-monks.htm" rel="nofollow">http://www.howtobefit.com/tendai-marathon-monks.htm</a>