Wednesday, February 25, 2009

Anaerobic Exercise

Aerobic exercise is big on today's health and fitness scene. Walking and jogging are the two main aerobic activities, although cycling is also popular. Walking and cycling are preferable to jogging because of cumulative damage caused by the high-impact nature of the activity.

Joggers who run for three, four or five miles every day are doing harm to feet, knees hips and back that may not show up for decades. Some, like a jogger I knew who was in his late forties, never made the connection between his favorite activity and his chronic back troubles.

Anaerobic exercise begins when the muscle cells need to oxidize fuel faster than your blood can carry oxygen to them. Here is an explanation from the Wikipedia article:

Anaerobic exercise is exercise intense enough to trigger anaerobic metabolism. It is used by athletes in non-endurance sports to build power and by body builders to build muscle mass. Muscles trained under anaerobic conditions develop differently, leading to greater performance in short duration, high intensity activities, which last up to about 2 minutes.

Aerobic exercise, on the other hand, includes lower intensity activities performed for longer periods of time. Such activities like walking, running, swimming, and cycling require a great deal of oxygen to generate the energy needed for prolonged exercise.

There are two types of anaerobic energy systems, the ATP-CP energy system, which uses creatine phosphate as the main energy source, and the lactic acid (or anaerobic glycolysis) system that uses glucose (or glycogen) in the absence of oxygen. Events or activity that last up to about thirty seconds rely primarily on the former, phosphagen, system. Beyond this time aerobic and anaerobic glycolysis begin to predominate. Anaerobic glycolysis uses glucose inefficiently, and produces by-products such as lactic acid that are thought to be detrimental to muscle function; this limits activity based predominantly on anaerobic glycolysis to about 2 minutes. The effectiveness of anaerobic activity can be improved through training.

Note that [i]t is used by athletes in non-endurance sports to build power. Power is a function of both strength and speed. One athlete can do thirty pushups in 25 seconds while another of comparable weight can do them in 15 seconds.

While both athletes are performing the same amount of work (force x distance), the second one has more power, more pushups per second.

In another post I want to discuss the application of power in self defense training.

2 comments:

Stephen said...

Thanks for this post.
I mainly jog for a workout, so I guess I should diversify a little bit. It's amazing how many exercises can actually be harmful to our bodies.

Craig Mutton said...

Swimming is also a good, no-impact aerobic workout that I forgot to mention in the post.