How Many Milliliters In A Liter

Anaerobic Work Has Its Limits

Today we will look at the important role that anaerobic development plays in developing the runner to high performance.

In Monday's post we discussed not only the cardiovascular and muscular benefits of heavy aerobic work, but also the fact that the aerobic base is virtually unlimited. The runner can develop this base and strength over many years. After all, no one runs an ultra during his first few months of training.

But as many competitive runners will quickly point out, the runner has to develop his speed, and for that he needs to do some anaerobic (without oxygen) work as well. The obstacle is that there is a limit to the ability to run in oxygen debt. Let's look at how Lydiard explains it, by the numbers.

"We know that the ability of the top endurance athletes to assimilate, transport, and use oxygen has an upper limit (VO2max) of about 7 liters per minute, or 85-90 milliliters per kilogram per minute. Suppose I have an athlete with a VO2max of 3 liters/minute. I explain to him that this can be improved.

No one knows what the limits are to the development of the cardiovascular system in any individual. What we do know is that our ability to incur oxygen debt, called anaerobic capacity, is limited to between 15 and 20 liters, so if I give this athlete with a VO2max of 3-liter/minute some anaerobic training, and in the 4 weeks it typically takes to develop this to its maximum, let's say we reach an anaerobic capacity of 18 liters. We have now reached the performance limit of the athlete, because it's physiologically impossible to increase the anaerobic capacity any further.

Now suppose this athlete carries out a workload that requires 4 liters of oxygen per minute. He is incurring an oxygen debt of 1 liter/minute (4 liters/minute required minus 3 liters/minute capacity), and can keep going for only 18 minutes at that speed (18 liters total oxygen debt divided by 1 liter debt each minute).

If we increase the workload to 5 liters/minute, he will incur an oxygen debt of 2 liters/minute (5 liters/minute required minus 3 liters/minute capacity), and can only keep going for 9 minutes at that speed (18 liters debt divided by 2 liters debt each minute). Therefore, oxygen debts not only double, but square and cube, and as we get faster, the oxygen debt becomes very great with only small increases in speed, eventually causing neuromuscular breakdown, or failure.

The only way to improve this athlete's performance limit is to increase the base (aerobic capacity). If it can be raised be from, say, 40 ml/kg/min in the first year, to 50 ml/kg/minute in the second year, and so on, I can improve the performance level with the same anaerobic capacity, so the performance level is governed by aerobic threshold, not by anaerobic development, and this can be improved year by year with what I call marathon training, or the aerobic volume of training.

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