I was pleased to receive a comment from Brent to the article on "The Case for Distance Training". It would be best to read his comment in full, Prime Boosts but if you are in a hurry I have attempted to extract his crucial points and copied them in the summary below. "Please tell me - what does 20,000 or even 14,000 yards a day do for a sprint swimmer? Why would someone racing for less than a minute need to train aerobically so much? This article talks a lot about who is training with this much yardage, but not about why they do it. I am not saying that lots of yardage is never good, but it isn’t for everyone. Fact: distance training decreases maximal stroking power. Fact: maximal stroking power is continually shown to be very highly correlated to maximal swimming velocity. In my opinion, the benefits of lots of yardage are not worth the loss of power in sprinters.

Brent is quite right. No one should swim 100 kilometers every week just because Phelps or Lochte are reported as swimming that far. That’s asking for far too big a leap of faith. Of course there should be a good reason. After all it’s a bloody long way to swim. Only a complete moron would do it without some idea of it physiological outcome. So what does happen when an athlete swims 100 kilometers a week for 25 weeks a year? In the five years it takes to develop an international level of aerobic fitness that’s 125 weeks and 12,500 kilometers; or New York to Los Angeles three and a bit times. Here is a simplified description of the physiological changes that occur. Remember though I’m not a doctor. However the descriptions are accurate even if they are not couched in medical terms. First there is a 40% increase in the density of the muscle’s capillary bed. A detailed study completed in Poland recently concluded with the following statement.

So what is the practical effect of these changes? One National Champion I coached began by swimming 26×200 meter sets in 2.45 with a heart rate of 160. Four years later the same swimmer was swimming the same set on the same interval, at the same heart rate in 2.16; same effort 18% faster. All the physiological changes mentioned above had occurred. Check this out swimmer could now swim at a 100 meter rate of 1.08 without dipping into her anaerobic mechanisms. At its most simple the faster you can swim aerobically the further ahead you start and the faster you will swim when you dip into your anaerobic and speed energy systems. And that’s true whether the event is 50 or 100 or 200 or 1500 met100 meters butterfly. Before his swims we spent ten weeks doing all the stuff Barry would drool over. For ten weeks he never swam further than 16,000 in a week. But he did it on top of a steady aerobic base. That’s why it worked.