Comeback Trail - Page 3
What about Joe and Sharon's fuel levels? Glycogen—the fuel stored in muscles and the liver—is a major source of energy for endurance runners. Joe's glycogen stores decreased by more than 40 percent after four weeks of inactivity, and Sharon's only slightly less, around 30 percent.
And while Joe and Sharon were not running, they likely lost as much as 43 percent of their slow-twitch (endurance) muscle fibers. The majority of this reduction takes place in the first two to four weeks, but Joe's loss will be steeper because of his complete inactivity. However, Sharon's longer running layoff has resulted in a similar loss. Combined with these other myriad changes, Joe and Sharon would find their racing times significantly slower, almost at their pre-training levels.
Joe and Sharon's situations illustrate how critical it is that runners never stop training entirely, even in off-season. Joe, being initially fitter than Sharon, faces a longer, more difficult battle to regain his lost fitness. It could take up to six months for Joe to completely retrain, due in part to his age. Evidence shows it takes longer to retrain as you age, because as we age we lose fast-twitch muscle fibers, fiber strength and muscle elasticity. Thus, our ability to contract our muscles at maximal or sub-maximal levels is reduced, especially during aerobic activity.
Joe's return to training should be very gradual, because he is completely de-conditioned and severely debilitated from his illness. He should start walking two to three miles, several days each week, and gradually add jogging "bursts" of two to three minutes, with a two- to three-minute recovery walk. He can increase his jogging stints by two minutes every week, until he is running his former weekly mileage, which will take four to six months. It will require a few more months to regain his anaerobic threshold and maximal oxygen uptake levels. With his mileage base re-established, Joe will be ready for speed work by the seventh or eighth month.
Sharon also faces a long comeback trail but has the advantage of not being debilitated from illness and being younger. Therefore she'll bounce back in three to four months. She can start jogging two to three miles a day, and add a mile to each run each week. By building up to weekly long runs of two to three hours for the last two to three months, Sharon will be ready for an ultra in six months.
Roy Stevenson has a master's degree in coaching and exercise physiology from Ohio University. He competed in New Zealand championships on the track, road and cross country, and has coached hundreds of Seattle-area runners.
Dodge the Decline
- When runners stop training completely, or cut back on workout intensity by one or two thirds (even if they run just as often and as far), their VO2max drops dramatically.
- If, however, the intensity is unchanged and frequency and duration is reduced by as much as two thirds, VO2max can be maintained for up to 15 weeks.
- So, if Sharon had knocked out regular 20- to 30-minute tempo runs in Asia (see main text), she would have had little decrease in her VO2max for the first four months of her vacation, and would face a much shorter retraining period.
- Ultrarunners who want to retain their aerobic fitness should never stop running (or cross training) completely unless they are sick or injured.