A story about intervals

Intervals. I dread them and love them. I have been doing them for years, ever since joining the track team in 5th grade. In high school, I kept running and started swimming. Both sports rely on interval-based training. In college, I did crew. More intervals. Now I'm biking and all winter long I've been doing intervals. I recently read a great story about them. It's from a book Once a Runner by John L. Parker. But I read it in Going Long: Legends, Oddballs, Comebacks and Adventures. The Best Stories from Runner's World.

"Twenty quarters [quarter miles] in sets of five, 110 jog btw the quarters, 440 jog between the sets, 62-63 second effort."

That's the workout the coach prescribed in the book. After the first set of 20 intervals, the coach tells his distance protege to do 20 more. At the end of 40, the coach says he has 20 left. The distance athlete is left running long into the night.

I only do intervals if I have a coach telling me I have to do them. As a Christmas present, Jeff gave me an awesome gift: free coaching for a number of months. All winter long, I have been working with Chris Newell from Sublime Athletics. He coaches a lot of athletes in Baltimore, and has been giving me weekly training plans. Most of them involve intervals on the bike trainer or road if weather permits. I have to log my workouts on Training Peaks, which keeps me accountable. If I didn't have a coach, I would skip the intervals and just do lots of long endurance steady state zone 3 workouts. The kind of workouts that are fun and build an aerobic base, but don't make you faster at anything.

"They began. The first few always seemed especially bad. Actually that was misleading. They seemed sluggish because the body was shocked by such a sudden demand for sustained speed. The heart rate shot up to the hummingbird levels it would have to maintain for some time. The legs became prematurely heavy, and the central nervous system sent up the message that such punishment could not be endured."

This is exactly how my interval work usually starts. The first ones are often the worst. I think it's partly because your body is shocked into a high output mode, but it's also mental. At the start of an interval session, there is so much more hard work ahead of you that it can be difficult to wrap your mind around actually finishing.

"The runner deals nearly daily in such absolutes of physical limitation, which the nonrunner confronts only in dire situations. Fleeing from an armed killer or deadly animal, a layman will soon find the frightening limits that even stark terror will not overcome. The runner knows such boundaries like he knows the sidewalks of his own neighborhood."

Interval work changes the body physiologically. In sedentary or recreational athletes, interval training can increase one's VO2 max by as much as 44 percent after just 10 weeks of training. VO2 max is a measure of aerobic fitness; it's the maximal amount of oxygen your body can take up and use to make ATP to power your muscles before lactic acid starts accumulating and your legs feel tired and heavy. Interestingly, in endurance-trained athletes, interval training has little effect on VO2 max. In endurance-trained athletes, interval training improves performance but through other mechanisms.

"Round and round the field they went, each repetition so much like the one before they had to count out loud lest they forget how many they had done....The only difference between one and the next was the slight increase in lactic acid in the lifting muscles on top of the thigh that made each a little more difficult and started hurting earlier in the sprint."

Highly trained athletes already have a high VO2 max. Their hearts are already strong and pump blood efficiently throughout the body. Their muscles have already adapted to exercise. Highly trained athletes have more type 1 muscle fibers, which are important for removing lactic acid, and their muscles have an increased density of capillaries, which means more blood flow and oxygen delivery. Muscle enzymes that make ATP have already adapted to work at maximal capacity. So in highly trained endurance athletes, it can be difficult to measure exactly how interval training increases performance.

"In a hail of killing blows, the fighter's quiet center of logic, schooled in brutality, will be calmly theorizing: We are hurt pretty badly. If we do not cover up and take up the slack we will soon be unconscious. Not that this quiet center logic fears unconsciousness (indeed, how welcome it might seem at times), but it knows that one can't win while unconscious. Likewise, no highly trained runner slacks off because he fears pain, but because the quiet center of logic says he will win nothing if he runs himself to a standstill."

In elite athletes, interval training improves performance through a number of proposed mechanisms. It increases the heart's contractile force, which means more blood flow and oxygen delivery to the body. It improves heat tolerance by increasing blood flow to your skin and sweating rate. It may improve the ability of working muscles to produce and use ATP. Interval training has been shown to provide athletes with a greater ability to buffer acid build-up. Acid inhibits the oxidative enzymes that make ATP, so athletes who can buffer acids can make more ATP to power their muscles. But I think the most important part of endurance training is the mental toughness it instills. Interval training forces you to overcome that quiet center of logic that says stop and seek safety. It re-teaches your brain to allow you to run yourself into the ground. It means that in a race, your body will be primed for peak performance and your mind will know how to push it even further.

"Just as each repetition made the next seem more impossible, he knew that without question he would do it. There was no refuge in injury; his body could not be injured in this way. There was no refuge in mercy; there was nothing to forgive, no one to issue dispensation. And at last he saw: there was no refuge in cowardice, because he was not afraid. There was no alternative; it just had to be done."

At the end of the day, this is how an interval workout gets finished. As the workout progresses, resolution sinks in. There is no place to escape to until the intervals are done, no option to spend the present time in any different way. Once started, intervals must be finished because any other scenario will render all that initial work for nothing. So the mind focuses on overcoming each little hurdle and steadfastly ignores the pain in the legs, the pounding heart and the trouble breathing. There is no alternative; the intervals just have to be done.

"When he finally trotted on, he looked up at the bright, clear stars and his eyes welled; mixed with the hot sweat of his face, tears ran down to the spittle around his mouth and chin, and he felt quite literally that he was melting, turning into human slush as he jogged along. Only when he started a repetition did he become solid once more."

When I first read this story, I thought it was real. I believed this Olympic-bound runner actually did 60 intervals around the track, 40 more than he originally thought he was going to have to do. For about a month, whenever I had an interval workout, I thought about this runner and knew that if he could push himself to such extremes for hours on end, then I could get though just 1 hour on the trainer. I found out later that this story is one of fiction. But I still like it. I'm sure someone out there has read this story too and has actually gone out to do 60 quarter mile intervals or something equally as long and hard. Maybe one day I will try that. Fictional or real, I think this story captures exactly the sentiments and lunacy that at a lot of athletes experience when faced with prescribed interval workouts and touches on the importance of mental toughness that interval training builds.