Sunday, May 31, 2009

The End-of-Season Decline

Rob Shoaf was a little light haired fellow from Trinity High School. He liked to crack jokes. We were friendly. At any given race, though, I felt I should beat him.

Immediately after the cross country season we arranged to drive together to Bowling Green for the Wendy’s 10K Classic. Dave Lawhorn, my teammate at Atherton, rode shotgun. Shoaf took the back seat. He brought a cooler. For the duration of the trip he cracked beers. He offered them up to the front seat. We declined, of course. I gave a knowing look to Dave. We could add another item to the list of reasons I should beat him.

When track or cross country season ended, I would take a week or so easy, and then ramp back up to a regular training schedule. Shoaf took a month off. I made every commitment to prepare for competition. Shoaf seemed to lag into every season, coaxed along by his coaches.

When the starter gun fired, Shoaf and I ran near to each other, as we had during much of the cross country season. He started to fade mid way through the race. I rolled on, as expected. A mile and a half later, Shoaf runs up alongside me. “I had a little cramp,” he says. He proceeds to pick up the pace. I’m unable to respond.

Shoaf and I traded victories. Mine came throughout the regular season, his came at the championship events. I always liked Shoaf, I just resented that he somehow managed to beat me when it counted. And he partied while I was home sleeping.

I have run many seasons since then. Competitive runners with long careers must cycle through phases of work and rest. Continuous improvement never is. Runners who don’t take a break typically break down. After my first season of cross country in high school, I continued on to the regional and national junior Olympics competition. Although I finished respectably, I felt “stale” at those races. When I continued to run in preparation for indoor track, I was finally forced to take a break because of tendonitis in my hip.

Starting from a baseline of general fitness, but little or no specialized training, athletes can quickly build aerobic capacity. We impose demands on the body, and the body adapts. The increasing fitness can be very motivating. Good coaches know that adaptation really occurs on rest days, as the body restores what has been broken down. They will sometimes have to bridle the horses who push themselves day after day.

Work-rest cycles certainly characterize a typical training week. It is harder to conceive why work-rest cycles must also characterize training at longer time-scales. Several weeks of hard work must be followed by an easy week, for example. And several months of hard work must be followed by an easy month. Why? If you go out on the track and do several fast repeats, not only will you feel tired afterwards, but you will likely have incurred muscle damage. It makes sense that you would need to wait long enough for muscle tissue to repair itself before you do another track workout. Are there analogous processes that occur over longer time-scales?

Conventional wisdom among ultrarunners holds that end-of-season breaks allow connective tissue to heal itself. The idea seems to be that while muscle builds quickly (a few days) connective tissue builds more slowly (a few weeks).

Injury, however, is not necessarily the bane of every runner who refuses to take a break. The more insidious problem is the performance plateau, or even decline, that extended seasons often bring. Rapid improvements in performance are very typical for athletes who have a reasonable fitness base, but are coming off of a period of rest or inactivity. As training continues, however, the rate of improvement will decrease. Most athletes who continue to train without a substantial break, even if they are able to continue running, will see a decline in performance. What, I always wondered, is the measurable index in the body that declines along with performance? Does mitochondrial density decrease? Do the raw materials for metabolic enzymes run low?

The pretext for much of my writing has been to establish natural explanations for human performance. I don’t want to invoke mysterious powers of will or spirit to explain how athletes strive and achieve. I don’t even want to use the term “mind” as if it works in a different way from the rest of what constitutes us. It is understandable, then, that I would search for the physical substrate of declines in performance. I can’t ignore, however, the most obvious index of declining performance: decreased motivation. Athletes who have been training hard for an extended time become lackadaisical. They don’t care as much. I recalled feeling “stale” toward the end of my first extended season. I could continue my search for the physical substrate that explains both declining performance and declining motivation. We can all accept that depletion in the body will cause decreased motivation “in the mind.” [This makes treating the body and mind separately unnecessary] But this would ignore the interesting possibility that we don’t need a physical parameter to explain the end-of-season blahs.

Imagine identical twins (Adam and Bob) on treadmills on opposite sides of a large gym. We have them hooked up to measure oxygen uptake, blood sugar levels, glycogen stores, and skeletal muscle activation. We start the treadmills and run them at the same speed. After a warm-up we tell Adam he has 10 minutes to go and Bob he has 30 minutes to go. We then ask each to rate his level of exertion. Adam reports a higher level of exertion than Bob, although all the measured physical parameters were identical. After the conversation, however, Bob’s skeletal muscle activation decreases compared to Adam’s. Although the experimental set-up is imaginary, it reflects the real results of experiments conducted by Tim Noakes that I referred to in an earlier post.

The critical finding is that what we anticipate at the beginning of a workout will affect our perception of effort, which will in turn affect our skeletal muscle activation. “What we anticipate” is, of course, a state of mind. While I certainly hold that states of mind exist naturally (via physical changes in the brain), the significant feature of these brain-states is their perceptual meaning. The meaning of “you have 10 minutes to go” depends on prior experience (like the last time you ran for 10 minutes on a treadmill), and, importantly, that perception will feedback on how your muscles are activated.

I suggest we look for a similar mechanism governing the experience of seasonality. At the beginning of the season we know there is “a long way to go.” We rapidly improve in fitness. Toward the end of a season, we know that “the end is near.” We have slow or stalled improvements to motivate us. Workouts of similar quality may require more effort (as perceived by the athlete). The result may be a slow decline in performance, even without the depletion of the body.

Our findings may suggest ways to manage our activities so that we can get the most out of them. We may find that the phased training employed by athletes and coaches with seasonal breaks, stumbled on by trial and error, is the best solution possible. Rob Shoaf “accidentally” managed his seasons so that he peaked when the stakes were highest. He took lengthy breaks, starting his seasons slowly, and kept a lighthearted and spontaneous approach to racing and training. I guess I’m hoping that a methodical approach can yield even better results.

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