Road racers rejoice! The season is coming to a well-earned finale for most of the World and it’s time for a tasty beverage, a big couch, and a slice or two of pizza! Or is it? Should you take a break or keep your foot on the gas? Let’s weigh the arguments.
Weekly training stress, intervals heaped upon intervals, how much do you weigh? These are the habits and dailies of the racing cyclist. After months upon months of them surely you deserve a break, a rest, a respite, don’t you? You’ve likely earned one, but then again if your training plan was well designed and well executed you shouldn’t be quite as shelled as your body and brain may wish. Indeed you probably have a solid foundation for a fall fitness push.
Which Is Better
To rest or to train—that is the essential question today. What rationale is there for taking a break? How long should it be? What happens when I do? Will I benefit more if I keep training? What about racing some cyclocross this fall?
In the “old” days (as far back as, gasp, the 90s!) racers would routinely put away the bike for weeks on end, sometimes months. Then they would slowly begin to build back the aerobic base that sets the stage for the coming season. As racing has become more specialized and the off-season ever shorter, the days of sitting on the couch and putting on weight are (some say, sadly) over.
Without question taking time off of structured training is an essential part of a responsible training plan. If you’ve been going full tilt since the spring, your body needs the rest and recuperation. Your mind probably needs it even more. So, first I am not advocating a 52-week training calendar, far from it. I am advocating the continuation of your fitness regimen. After all, we are athletes by choice and lifestyle, and that doesn’t stop just because the calendar ticks over. Of course to my mind the “old schoolers” were putting the bike away at one of the most gorgeous times of the year to ride, so it made no sense to me.
Effects of Detraining
Ok, we’ve established that you need a rest. Great. But how long do you rest and what are the net effects on your body? Fortunately, Bryan Bergman, an associate professor at the University of Colorado Medical Center, wrote a great summary on the adaptations and effects of not training. Among his findings via a summary of over 50 relevant studies:
VO2max, Blood Volume and Mitochondrial Density
VO2max can drop by as much as 4-14 percent in as little as four weeks, according to Bergman. In the first three weeks this drop was attributed to decreases in cardiac output, while the final weeks drop was likely due to decreases in mitochondrial density. This loss of mitochondrial volume is most significant in the first eight weeks of detraining, but tended to stabilize at roughly 50 percent above sedentary control subjects thereafter.
Research suggests that the 50 percent increase in volume between sedentary and elite participants was due to the maintenance of training induced oxidative enzyme levels in fast twitch fibers, while slow twitch fibers returned to control levels. This is a major consideration for cyclists as it is a primarily aerobic sport, so you need to avoid prolonged inactivity or suffer the consequences as a mere mortal upon your return to training. Similarly, as little as a week of inactivity can also induce a loss of muscle glycogen stores, although it was not quantified how much of a loss to expect.
Blood volume begins to drop off after as little as two days of inactivity and after four weeks can be 12 percent. While most of this volume loss is plasma (water), up to 3 percent can be due to loss of red blood cell density, the delivery mechanisms of oxygen. Interestingly, capillary density (the amount of capillaries per fusing the muscle itself) showed little to no decrease in elite level athletes at the cessation of training.
All of these losses lead to a general decrease in endurance capacity of as much as 25 percent in as little as two to four weeks. Some of this decrease is likely due to an increased use of carbohydrate as a fuel source, according to Bergman’s summary. As you might infer given the above decreases, sub-maximal lactate concentrations tended to rise when training was stopped for as little as one week. Though no direct explanation was offered, it was postulated that the increase concentration was due to a decrease in lactate clearing.
Absolute Lactate Threshold also decreases with the end of training. This decrease stabilizes after 3 months or so. Changes in LT are vitally important to cyclists for, as Bergman summarizes, “High lactate threshold is one of the most important predictors of endurance performance. It takes a lot of time, even years, to increase lactate threshold to an athlete’s genetic potential, so it is vital to prevent a large drop during the offseason. Only by building upon the current season’s gains in LT, will LT increase from year to year to an elite level.”