What is running anaerobically anyway?

Oversimplification: anerobic = sprint or near sprint pace

aerobic = tolerable pace

Anaerobic means without oxygen. Basically any race lasting under 2 min is primarily anaerobic.

If you are young, this may ring a bell (layman's terms).

A race is anerobic when you sprint the first 400-600. That horrible feeling the next 400-600 is you trying to recover from putting so much lactic acid into your muscles and heart rate is high. Finally, after slowing dramatically, your body has processed the lactic acid somewhat, and you begin to fall back into an aerobic rhythm, before going anaerobic again at the end. The key is to keep pushing this line (theshold) higher and higher so you can go faster and faster without going over that line of no return and be in control of your race surging, kicking, etc. when you desire instead of when or if you can.

You don't just go "anaerobic" or "aerobic". Those are terms that describe where the energy is coming from. All activities are partly aerobic and partly anaerobic. Anaerobic means of energy production include Creatine Phosphate system and Glycolysis. You have stored in your body a limited amount of ATP (energy needed for anyting you do). This is used up within seconds and Creatine Phosphate "reenergizes" the spent ATP. You also have a limited supply of creatine phosphate in the body. Between the stored ATP and stored Creatine Phosphate you have enough energy for about 6-10 seconds of all-out work. This is Anaerobic and does not require the use of oxygen. So the energy required for the legs to move an elite sprinter 100meters is purely anaerobic. Glycolysis uses glucose (carbohydrates) to produce ATP. The byproduct of Fast Glycolysis is lactic acid whereas the byproduct of Slow Glycolysis is pyruvate. Slow Glycolysis is also the first step in aerobic energy production (Oxidation). Glycolysis is also anaerobic and does not need oxygen. Every race a runner runs from 100m on up requires both aerobic and anaerobic energy production. The buidup of the byproducts of Glycolysis (lactic acid and hydrogen, especially hydrogen) is what causes most muscle fatigue in races from 200m up to the half marathon. Under very easy exericse the lactic acid produced by glycolysis is shuttled out of the muscle and thus does not lead to fatigue. The more intense the exerice the more lactic acid builds up and thus the more "anaerobic" it is.

A 5k is partly "aerobic" and "anaerobic". The energy needs are somewhere in the range of 20% "anaerobic" 80% "aerobic". If you are hurting and your legs are getting stiff and tired then you are feeling the byproducts of glycolysis.

I hope this helps.

Alan

You are all wrong.

There is no such thing as "anerobic" or "anaerobic" running, and these terms are not acceptable even for the purpose of simply communicating the basic idea of energy systems.

Remember that a muscle does not function as a whole, but rather as a collection of individual muscle cells.

All of the muscle fibers utilize a certain percentage of both aerobic and anaerobic metabolism for contraction, and this percentage is constant regardless of how fast you run. The only difference between faster and slower running is that faster running recruits more fast-twitch fibers, and hence more fibers that utilize a relatively high percentage of anaerobic metabolism. However, the abolute amount of energy produced aerobically is actually GREATER during fast running, even though the percentage is lower. So, terms like "aerobic" and "anaerobic" running are quite inaccurate.

Thanks. So Alan, if its 80-20 for a 5k does that mean the first 80% of the race I am running aerobically and the last 20 % running anaerobically?

Good definition Art.

In any distance race the energy will come from a mix of aerobic and anaerobic energy.

At about the pace you can race for an hour, you will be at what is termed the "lactate threshold." Any slower than this and your body is producing a small amount of energy anaerobically which will break down carbohydrate without oxygen to form lactate ions. The body will remove these lactate ions as quickly are they formed and the lactic acid amount will stay relatively low.

If you run faster than that pace, for example in your 5k race, however the energy demands will be greater. There will not be enough oxygen present in the muscle fibers. The result is that the lactate ions will build up gradually and lactic acid will pool in your mucles and blood. If you race the 5K at an even pace the lactate level will rise throughout the race, peaking at the finish.

So to answer your question, the 20% will be spread throughout the race. Actually, the best way to race is to run more anaerobically toward the end. The reason is if the lactic acid gets too strong it will slow you down. At the finish that is ok because you are done. It is not ok with a lap to go with because the last lap will be slower. Really, at an even pace you are running 80% aerobic / 20% anaerobic the entire race, other than the very start. It is better to run slightly more aerobic earlier in the race and slightly more anaerobic the end (last 1K) of the race. That means you want to run a slightly slower pace than your predicted time the first ~4K and finish faster than that.

Basically "anaerobic" exercise produces a burn in your muscles due to some production of energy without oxygen. It occurs when you're running faster.

So you would, in a 5k, run APPROXIMATELY this way. Most of your energy for movement at a given time (holding your race pace) is produced using oxygen ("aerobic"). BUT 20% of the energy (perhaps - this is an approximation and varies from person to person) is produced by anaerobic processes, not requiring oxygen but building up lactic acid in your muscles.

Bottom line: The 5k is not a sprint, but you will feel a noticeable anaerobic burn during it. It'll be a more painful pace than, say, your average comfortable distance pace. Be prepared for discomfort - although it IS a distance race, it's relatively short and so you can run faster because you'll have less time in which to build up lactate. Be prepared to breathe hard - go look up "oxygen debt." You'll experience this in the 5k.