The process of adaptation begins with your genes. Training provides stimuli (e.g., glycogen depletion) that turn specific genes on or off. By altering the expression of genes, training changes the rates at which your body makes and breaks down specific proteins. For example, endurance training turns on genes for the production of mitochondrial protein. More endurance training leads to more mitochondria in your muscles so that you can produce more energy aerobically. Your muscles and cardiovascular system adapt over days, weeks, and months to the cumulative effects of your repeated training.
Runners vary greatly in how long it takes them to recover from and adapt to a workout. Differences among runners in recovery time and rate of improvement are determined by genetics, age (you tend to recover more slowly with age), training history, gender (women tend to recover more slowly because of lower testosterone levels), and lifestyle factors. Your genetics determine your predisposition to adapt to training; some of us are programmed to adapt more quickly than others. Lifestyle factors, such as diet, quantity and quality of sleep, general health, and various life stressors (such as work, finances, and relationships), all influence how quickly you recover from and adapt to training. Because so much variation exists among runners in how many workouts they can tolerate in a given period, you shouldn’t copy your training partner ’s running program. Only through experience will you learn how much training you can handle.
As an example, figure 3.1, adapted from Tudor Bompa’s Periodization Training for Sports (2005), details two runners who do the same workout and experience the same amount of initial fatigue but who recover at different rates. Rachel (represented by the solid line) recovers more quickly than Karen (represented by the dashed line). Rachel will be able to recover from and adapt positively to more high-quality workouts in a given period and will, therefore, improve more quickly than Karen. Rachel would also require a shorter taper before a race than Karen.
Only through trial and error will you know how much training your body can positively adapt to in a given time. Successful marathoning requires that you go through this self-discovery process intelligently and systematically. Determining this balance can be tricky because it can be hard to isolate variables. For example, if your job is now much more stressful than the last time you trained for a marathon, your current rate of recovery might be slower. You must find the correct balance of training stimulus and recovery for your specific circumstances over the long weeks that constitute marathon training.
Unfortunately, the scientific literature doesn’t provide clear evidence of the amount of time required to realize the benefits of an individual training session. Personal experience and discussions with many runners and coaches indicate that 8 to 10 days is an adequate amount of time to recover from and reap the rewards of most hard training sessions. Given that any one workout provides only a small fitness benefit – on the order of magnitude of less than 1 percent – but that a workout can cause severe short-term fatigue, it’s wise to err on the side of caution and allow enough time to fully recover from training before a race. For the marathon race itself, complete recovery from training is critical for success. Marathon tapering generally requires a full 3 weeks; tapering is the subject of chapter 5.
Table 3.1 shows typical times to reap the benefits of three major types of workouts. The third column indicates typical amounts of time to recover from a workout of each type. For example, the table indicates that you should allow at least 4 days between tempo runs or between a tempo run and a tune-up race. You don’t, however, need to allow 4 days between a tempo run and a long run or interval workout. That’s because each type of workout uses different combinations of energy systems, so complete recovery from one type of workout isn’t necessary before you do another type of workout.
Although you won’t see the benefits of this week’s workout in this weekend’s race, if you do the workout early enough in the week you should recover sufficiently for it not to have a detrimental effect on your race performance. The timelines in Table 3.1 take into account the fact that we often do a tune-up race when the fatigue of previous training is reduced rather than when supercompensation has occurred. You generally can’t afford the time required to be optimally rested for tune-up races. Marathoners should allow only enough rest and recovery to obtain optimal results for the marathon itself and possibly for one tune-up race.
Of the major types of workouts, tempo runs are the easiest to recover from because they don’t break down the body as much as the other forms of hard training. Tempo runs are neither fast enough to cause substantial muscle damage nor long enough to totally deplete your muscles of glycogen.
Long runs seem to cause the most variability in recovery time among runners, although replenishing glycogen stores generally requires only 24 to 48 hours. Some runners are able to recover relatively quickly from long runs, whereas others are wiped out for days after one. The variability in recovery time depends on your training history, the genetic and lifestyle factors discussed previously, the type of courses you train on (downhills cause more muscle damage and greater recovery time), and the weather (the same long run in 85-degree F [29-degree C] weather will take longer to recover from than one on a 50-degree F [10-degree C] day).
Interval workouts put your muscles and cardiovascular system under the most stress and generally require the longest recovery time. Later in this chapter, we’ll discuss strategies that you can use to speed your recovery.
Regardless of the type of workout involved, the pattern of workout and recovery is basic to effective training. Generally known as the hard/easy principle, this dictates the structure of your training over the weeks and months leading up to the marathon. Let’s investigate the rationale for following the hard/easy principle.
The Hard/Easy Principle
Conventional wisdom calls for following the hard/easy principle of training, which is typically interpreted to mean that a hard effort is always followed by 1 or more recovery days. A recovery day may consist of an easy run, a light cross-training session, or total rest. During your marathon preparation, however, it’s sometimes best to violate this training pattern and do back-to-back hard days. The appropriate interpretation of the hard/easy principle is that 1 or more hard days should be followed by 1 or more recovery days. Let’s investigate the physiological rationale for following the hard/easy principle and look at two situations in which you should do back-to-back hard training days.
The hard day/easy day training pattern follows from the physiological dogma of stimulus and response – hard training provides a stimulus for your body to improve, but rest is then needed to allow your body to recover and adapt to a higher level. Three reasons to follow the hard/easy principle are to prevent total glycogen depletion, to prevent illness, and to minimize the effects of delayed onset muscle soreness (DOMS).