CHAPTER 7

STRESS AND RECOVERY

As a runner, you not only fight individual battles against fatigue within workouts and races, but you also wage an ongoing war against fatigue throughout the training process. As we’ve already discussed, the faster and farther you can run without experiencing acute fatigue in a workout or race, the better your performance will be. But the same principle also applies on a broader scale, in the sense that the more total running—and especially the more race-specific running—you are able to do from week to week without succumbing to persistent or chronic fatigue (or injury), the more your running performance will improve.

In most hard workouts and races, you start off feeling fresh and finish feeling fatigued. But sometimes you feel fatigued from the very first step of a run. If this happens only once or twice a week, it’s nothing to worry about, especially if it happens on days when you do not have a key workout scheduled. If you begin to feel “prefatigued” on a regular basis, however, even on key workout days, you have a problem: Your body is not fully recovering from the stress of your workouts and, as a result, you’re not building fitness as quickly as you should be, if at all. In a word, you are overtraining.

Most runners think of acute fatigue (the kind of fatigue you feel at the end of a good run) and overtraining fatigue (the kind you feel at the beginning of a bad run) as being completely different, but in fact they are very much the same. Both types of fatigue are brain-centered ways of forcing you to slow down or stop so you don’t harm yourself.

As we’ve seen, during any given workout or race, fatigue is the performance limiter. You can run only so fast for so long before your brain begins to receive warning signals of impending health risks through afferent feedback from the body. For example, during a short, fast race, rising muscle lactate levels might trigger pain receptors that warn your brain of increasing muscle acidity, which could cause muscle damage if allowed to go too far. Your brain responds to these signals by creating feelings of discomfort and inhibiting motor output to the working muscles, causing you to slow down and avert the health risk.

A similar system operates at the level of long-term training. Sometimes, as runners increase their training workload in preparation for a peak race, they cross a threshold beyond which body tissues, organs, and systems are no longer able to properly recover from the previous workout stress before the next is administered. Thus, as the training workload increases, tissue damage caused by running begins to accumulate, threatening not only these tissues themselves but also the immune and neuroendocrine systems, which are responsible for repairing tissue damage and enabling tissues to adapt to the stressors (in this case running) that are causing it. At some point it becomes a losing battle, and the body sends signals to the brain conveying this message. The brain responds by producing symptoms to discourage continued training at the present workload. The runner begins to feel flat, tired, and heavy in the majority of his or her workouts. Post-workout muscle soreness becomes almost constant. Motivation plummets.

One of the main concerns of every runner should be to avoid the downward spiral of accumulating muscular, immune system, and neuroendocrine system stress that characterizes overtraining. Of course, the easiest way to avoid overtraining is to train very lightly, or not at all. The problem with this approach is—quite obviously—that running performance is closely correlated with training workload. In other words, the harder you train within the limits of your body’s recovery capacity, the fitter you become. So your true objective in relation to the danger of overtraining is to consistently train as hard as you can without exceeding your recovery capacity, and in ways that increase your maximum training limit.

In the following sections I will show you how to strike this balance using the brain training system of integrating subjective feedback (how your body feels), objective feedback (your training numbers), and collective feedback (the latest scientific knowledge of what’s really going on when you are experiencing overtraining fatigue). My brain training methods of balancing training stress and recovery are somewhat different from conventional methods, primarily because they are based on the new, brain-centered conception of overtraining fatigue. Before I share these methods, let me first say a little more about the brain’s role in overtraining fatigue.

STRESSED OUT AND INFLAMED

The word “stress” is given a variety of meanings in everyday speech, but its scientific meaning is very precise. Stress is a specific set of physiological reactions to perceived threats to the organism. A good example of a threat most runners can relate to is a growling dog. Such threats are perceived by the hypothalamus gland deep inside the brain, which initiates a cascade of nervous system and hormonal events that focus attention on the threat, increase fuel breakdown (to provide energy for fighting or running away), stimulate the immune system (in case an injury occurs), and reduce noncritical functions, such as digestion (to spare energy).

The stress response is an indispensable asset for handling threats, but when threats occur too frequently or persistently, the organs and systems involved can be thrown off balance and break down. For example, one of the most important stress hormones is cortisol, which is produced by the adrenal glands. When the adrenal glands are forced to produce too much cortisol too often, they may wear out and become unable to produce sufficient cortisol to handle future threats. But before that happens, chronically high cortisol levels are likely to suppress the immune system, cause weight gain, and even cause the brain to deteriorate.

We are accustomed to thinking of stress as beginning with information that reaches the brain through the senses. Examples include an argument with one’s spouse and a near accident on the freeway. But the stress response may also be triggered by physical events, such as a bacterial infection or injury. Exercise is another physical stressor. A hard run triggers the release of stress hormones, stimulates the immune system, and so forth. The stress response to exercise not only enables the body to better meet the challenge of a hard run, but it also causes many of the positive physiological adaptations to training, such as increased resistance to exercise-induced muscle damage. But as with other stressors, if exercise is too extreme, such that it outstrips the capacity of the stress response to consistently restore homeostasis to the body between workouts, a loss of balance may occur.

Both psychological and physical stressors cause immune cells to produce cytokines, which are chemical messengers that provide two-way communication between the brain and the body. Cytokines released from peripheral organs and tissues provide information concerning a threat, injury, or infection to the brain. In turn, the brain responds by initiating appropriate reactions in the nervous, endocrine, and immune systems, again using cytokines to coordinate the reactions. In the case of injuries and infections, the brain uses cytokines to produce an inflammation response.

Inflammation is a key player in overtraining fatigue. Tissue damage that occurs during and after running triggers the inflammation response, an immune system process whose purpose is to remove cellular debris from the site of damage and initiate repair. There are three phases of the inflammation response. First, blood vessels upstream from the site of damage dilate, increasing blood flow to the area. At the same time, blood vessels downstream from the site of damage constrict, causing blood to accumulate there. This flooding effect causes the classic symptoms of swelling, heat, and stiffness that are associated with inflammation. Next, specialized white blood cells called neutrophils migrate to the injured area and absorb the debris of damaged cells. Finally, other cells known as macrophages accumulate at the site of damage to complete the cleanup process and stimulate tissue regeneration.

Inflammation does several important things for runners. First, as mentioned, when a significant injury occurs, inflammation heals it and also produces symptoms of pain and stiffness that discourage activity during the healing process. If inflammation did not produce these symptoms, we would probably continue training as normal despite our injuries and make them continually worse until total dysfunction forced us to stop.

Most of us associate inflammation with acute injuries such as ankle sprains. But a much milder inflammation response occurs after normal workouts in which we do not suffer any serious injuries. Every workout causes microscopic damage to muscle fibers, which are repaired with the aid of inflammation during the following recovery period. The main cause of muscle damage during exercise is eccentric (pronounced “ee-centric”) muscle contractions, which are also known as lengthening contractions. An example of an eccentric contraction is the lowering phase of a biceps curl. During this action the active muscle fibers are essentially pulled in two directions as they resist the force of gravity, but not enough to overcome gravity and shorten, so they actually lengthen while “trying” to shorten. Eccentric contractions occur at various moments in the running stride —most notably at footstrike, when the quadriceps and other muscles are forced to lengthen by ground impact forces but contract to absorb these forces and prevent the collapse of the joints they attach to. The strain of these lengthening contractions results in damage to some of the sarcomeres that are linked together like a chain to form a muscle fiber. Sarcomere damage produces chemical signals that trigger the process of inflammation, which begins about two hours after a workout and typically resolves after 48 hours.

In addition to repairing everyday muscle damage from exercise, inflammation promotes training adaptations such as satellite cell proliferation, an essential step in the development of bigger, stronger muscle fibers. Inflammation even makes the athlete more resistant to muscle damage in the future—a phenomenon known as the repeated bout effect. Studies have shown that untrained individuals become more resistant to exercise-induced muscle damage after just a single workout. It appears that the inflammation response triggered by the first workout increases the activity of neutrophils in the next workout, protecting the muscle fibers from some of the damage that would otherwise occur.

There is a negative side to inflammation, however. Ironically, although inflammation repairs tissue damage caused during exercise, it also causes further damage, known as secondary muscle damage, between workouts. Secondary muscle damage is believed to be caused at least in part by the release of free radicals from active neutrophils. Secondary muscle damage is the main reason you feel sorer the morning after a particularly hard workout or race than you do right afterward, and why you sometimes feel sorest two days after the workout or race. This phenomenon is aptly referred to as delayed-onset muscle soreness (DOMS).

More than an unpleasant feeling, DOMS is a symptom of muscle tissue damage that can seriously compromise the quality of your training while it persists. A recent Spanish university study found that DOMS reduced running economy in a group of trained runners by more than 3 percent (which is a significant amount, considering the fact that a lifetime of training may only increase running economy by 10 percent). The loss of efficiency seen in athletes experiencing DOMS stems from changes in their normal movement patterns. These changes also place unaccustomed stress on the joints, increasing injury risk. In another study, cyclists with DOMS exhibited higher than normal heart rates, blood lactate levels, and cortisol levels during a workout, indicating that when lingering muscle damage exists, normal training becomes more stressful to the body. DOMS has even been shown to delay muscle glycogen replenishment (that is, muscle refueling) after workouts, leaving less energy available for the next session.

In runners who train hard every day, inflammation may not be entirely resolved and muscle damage may not heal adequately between workouts. When runners persist in training too hard and resting too little, they risk entering a cycle of persistent tissue trauma and chronic inflammation. Some exercise scientists believe that this cycle is at the heart of overtraining syndrome, a disorder that is characterized by loss of performance, low motivation, compromised immune function, disturbed sleep, and other symptoms. Athletes suffering from overtraining syndrome exhibit abnormal concentrations of cytokines, which are responsible for transforming the localized inflammation response at the site of damage into chronic, whole-body (or systemic) inflammation. Overtraining syndrome is a serious condition that sometimes requires months of recovery time. It is somewhat rare, but a less severe pattern of compromised training and recovery that results from exercise-related tissue damage and inflammation is common among competitive runners.

Joint tissues (tendons, ligaments, and cartilage) also suffer damage during exercise (especially when there are biomechanical irregularities) and undergo a subsequent inflammation response. When joint tissues fail to regenerate fully between workouts, they may become chronically inflamed and/or degenerate to the point of serious injury. Some overuse injuries that are all too familiar to runners—including runner’s knee and Achilles tendinosis— develop in this manner.

In summary, inflammation is a double-edged sword. Without it, our bodies could not heal tissue damage incurred during exercise, or gain fitness in response to workouts, or develop greater resistance to muscle damage in subsequent workouts. In competitive runners who train hard, however, inflammation can become a problem unto itself, causing secondary muscle damage between workouts that compromises our recovery and performance and may even lead to injuries.

TRAIN TO RECOVER, RECOVER TO TRAIN

Most runners become injured before they are able to train hard enough for a long enough period of time to develop full-blown overtraining syndrome, which is seen almost exclusively in elite athletes. Garden-variety overtraining, or training staleness, is a phenomenon that most competitive runners experience now and again, however, and the fitness development of all competitive runners is limited by their capacity to recover from the stress of training. The secret to maximizing your fitness development, therefore, is to enhance your recovery from workouts and to increase the training workload that you are able to adequately recover from between workouts. There are two general strategies you can use to achieve these objectives. The first strategy involves finding better ways to balance training stress and recovery—that is, to apply the right types and degrees of training stress at just the right times. The second is to facilitate recovery by getting the most out of three lifestyle factors that promote recovery: nutrition, sleep, and stress management. Following are some specific methods you can use to prevent overtraining fatigue from hampering your running.

Know Your Limits

Your running fitness will reach the highest level for a peak race if, throughout the training cycle that precedes it, your training workload is just slightly less than the most you can handle without experiencing overtraining fatigue. There is extreme variability in the amount of training stress individual runners can handle. Nevertheless, all runners can increase their training capacity over time.

The only way to know your training workload limit is to exceed it every once in a while. As long as it doesn’t happen too often (more than once or twice over the course of a training cycle), and the transgression is slight, such that you never experience anything worse than a brief stale patch in your training, and you reduce your training workload quickly in response to this experience, you will be okay—better off, in fact, than if you trained very conservatively and never neared your limit.

To begin, follow a training plan that you expect to keep you just on the safe side of overtraining, based on past experience. If, at any point in your execution of this plan, you encounter a period in which you feel lousy in several consecutive workouts, give yourself a chance to recover by taking a day off and doing only recovery workouts for the next few days. When you resume normal training, reduce your overall workload slightly (5 -15 percent) for the remainder of the training cycle.

If you feel far from overtrained as you move through your planned training, feel free to experiment with efforts to increase your training workload a little more than planned. Proceed cautiously, by adding just a few minutes to key workouts or by adding one additional recovery running or cross-training workout to your weekly schedule at a time. Again, if you hit a stale patch, pull back slightly and wait until the next training cycle to increase your training workload further. If you train well and feel good all the way to your peak race, you can increase your training workload somewhat more aggressively in the next training cycle.

The bottom line is that it’s good to overtrain very slightly and very briefly every once in a while, because it provides useful information about your current limit that you can use to your benefit going forward. This cautious, conscious way of overtraining is sometimes referred to as “overreaching” to distinguish it from the more careless and thoughtless way of overtraining.

Learn Your Recovery Profile

All runners are unique in terms of how they recover from training. Some runners recover faster from long runs than from high-intensity runs, while other runners do the opposite. Some runners experience big fluctuations in their recovery speed as their fitness level changes, while others are more consistent in their recovery. There are many other examples of differences in individual recovery profiles I could list. By paying attention to and learning how your body recovers from training—your personal recovery profile—you can adjust your training in ways that enable you to perform most of your key workouts at a high level and minimize overtraining fatigue.

For example, in paying attention to my own recovery, I discovered that I tend to get stronger and stronger as the week progresses. I responded to this observation by tweaking my training schedule so that I train very lightly on Monday and Tuesday, waiting until Wednesday to do my first key workout, and I do my hardest workouts on Friday and Sunday. Back-loading my weekly training schedule in this manner leaves me feeling even more of a wreck on Monday and Tuesday, but it works out for the best because it also enables me to do my hardest workouts when I feel strongest.

Nothing is off limits when it comes to adjusting your training patterns to maximize your key workout performances and minimize overtraining fatigue, as long as each adjustment is a sensible response to a consistent self-observation. You can run twice a day three days a week instead of once a day six times a week if the former pattern seems to work better for you. Or you can do key workouts on back-to-back days and wait three days to do your third weekly key workout. The worst that can happen is that you try a new training pattern based on a hunch and find that it doesn’t work out, so you go back to your old pattern.

Train Responsively

In chapter 1 I defined responsive training as modifying your planned workout as necessary depending on how you feel immediately before or after you start running. Responsive training is most crucial in key workouts. If you’re too fatigued from previous training (or whatever else) to perform adequately in a key workout, you’re better off doing an easier alternative workout instead.

In my experience, it is seldom possible to anticipate ahead of time whether you are going to perform well or poorly in a key workout. You just have to start running and then make a judgment about whether to continue based on how you feel. Here are some responsive training guidelines.

• Always complete your planned workout if you are hitting your target pace and feel at least “fair” on a scale of great-good-fair-bad-terrible.

• If you are failing to hit your target pace and you feel fair, cut the planned workout in half. For example, instead of doing 20 minutes of tempo running at 10K pace, do 10 minutes.

• If you are failing to hit your target pace and you feel bad, switch to an easier key workout featuring short intervals at a high intensity. Runners usually feel and perform better on their flat days when they shorten and speed up their high-intensity efforts. I have no idea what the neurophysiological mechanism behind this phenomenon may be, but that doesn’t make it any less real. So, for example, if you start a 20-minute tempo run at 10K pace and feel bad, try switching to 5 × 400m at 5K pace. You’ll probably feel better and you’ll get more out of the workout than you would if you had to resort to the next option, which is this:

• If you are failing to hit your target pace and you feel terrible, switch to a recovery run. Make the run as short and slow as necessary to feel at least “fair” (you probably won’t feel any better than fair on such days).

Practice Recovery Nutrition

Nutrition is one of the most important influences on the body’s ability to absorb and adapt to training stress. In particular, the right nutrition habits will strengthen your immune system, accelerate postrun muscle tissue repair, and minimize inflammation. The two most effective nutritional means to enhance muscle recovery are maintaining a diet that’s high in antioxidants and consuming fluids, carbohydrates, and proteins within the first hour after completing exercise.

Antioxidants are nutrients that neutralize the free radicals that are released from damaged muscle cells. Vitamins C and E are perhaps the best-known antioxidant nutrients. Many runners try to boost their levels of antioxidants with supplements, but ingesting these free radical fighters in natural foods is the best way to get the volume and variety of antioxidants needed to maximize recovery. Many antioxidants work synergistically, so it’s preferable to get a balance of different antioxidants, as in natural foods, rather than taking just one or two antioxidants, as in supplements.

All foods contain antioxidants, but the best sources are fresh fruits and vegetables. Fruits and vegetables have not only vitamins C and E in them, but also dozens of other antioxidants, such as isoflavones, catechins, and carotenoids. For optimal muscle protection, consume seven to nine servings of fresh fruits and veggies per day.

Free radicals aren’t the only culprits that cause muscle damage long after you’ve completed a run. Stress hormones, particularly cortisol, tend to stay elevated for some time after exercise. Cortisol breaks down muscle proteins to release energy—which helps you function and refuel after a run, but also causes the damage that leads to sore legs.

You can counteract cortisol by eating and drinking as soon after a run as possible. By bringing hydration and blood sugar back to a normal state you limit stress hormone production and therefore limit the amount of muscle damage that can occur.

In addition to water, which increases blood flow to the muscles, the most important nutrients for quick muscle repair are carbohydrates to turn off the cortisol switch, and proteins, which provide the amino acids your muscles need to rebuild. Timing is all-important. In a study by Vanderbilt University, subjects were given a carbohydrate-and-protein supplement either immediately after a cycling workout or three hours later. The first group experienced a net gain in muscle protein, while the second group experienced a net loss, indicating they did not fully repair the muscle damage incurred in the workout. You don’t have to use a commercial recovery drink—although they work. A real-food mix of carbs and protein, such as a piece of chicken with pasta, or peanut butter on a bagel, is also effective. The important thing is to be fanatical about refueling immediately after a run.

Get Plenty of Sleep

Lack of adequate sleep is itself a stressor, so if you consistently undersleep, you will not recover from workouts as quickly and you will also be unable to handle as much training as you could handle if you did sleep adequately. As few as four nights of partial sleep deprivation result in skyrocketing levels of circulating cortisol. In addition, research in nonathletes has shown that short-term partial sleep deprivation increases circulating levels of C-reactive protein, a biomarker of inflammation. Therefore muscle damage-related inflammation is likely to be exacerbated by inadequate sleep.

How much sleep is enough? Sleep experts believe that there is a high degree of variation in sleep needs among individuals. It’s best to sleep until you are “slept out,” regardless of how much time it takes. In other words, you should sleep long enough so that you awaken spontaneously in the morning and couldn’t sleep more if you tried.

Sleep also benefits runners in ways that are more strictly brain-centered. For example, recent neuroscientific research has found that the brain actually practices motor skills (everything from running to playing video games) during sleep. In a study performed at Harvard Medical School, two groups of right-handed subjects practiced a rapid typing task with their left hand, at the end of which time they were tested for improvement in the skill. Then they waited 12 hours and were tested for further improvement in the task. One group was tested at ten a.m., following a practice session, and was retested at ten p.m. the same day without any additional practice. The other group was tested at ten p.m. and was retested at ten a.m. the next morning, after sleeping, and without additional practice. Members of the first group showed a 2 percent improvement when they were retested. Members of the second group, who slept between tests, showed a 20 percent improvement the next morning without any additional practice of the skill.

The lesson is plain: Much of the improvement in our ability to perform motor tasks, such as running, occurs within the brain during sleep. So if you want to get the most out of your workouts, get plenty of sleep!

Manage Your Life Stressors

Remember, the body does not distinguish among causes of stress. Any influence that triggers the physiological stress response will affect your body in more or less the same way; hence, the concept of the “total stress load” (also known as allostatic load), which refers to the total physiological effect of all the stressors in your life. There is a limit to the amount of stress anyone can handle, so the more non-running-related stress there is in your life, the less running you will be able to handle without experiencing overtraining fatigue. For the sake of your running and your overall health and well-being, you should make stress management a daily priority in your life.

Among the major sources of psychological stress in modern life are family and relationship conflicts, overworking, feelings of lack of control at work, commuting, and financial concerns. Among the most effective stress relievers are exercise, spending time with friends, laughter, practicing hobbies, meditation—and sex!

Get the Most out of Recovery Runs

If you asked a stadium-size crowd of other runners to name the most important type of running workout, some would say tempo runs, others would say long runs, and still others would say intervals of one kind or another. None would mention recovery runs. Unless I happened to be in that stadium.

Now, I won’t go quite so far as to say that recovery runs are more important than tempo runs, long runs, and intervals, but I do believe they are no less important. Why? Because recovery runs, if properly integrated into your training regimen, will do just as much to enhance your race performances as any other type of workout. Seriously.

It is widely assumed that the purpose of recovery runs—which we may define as relatively short, slow runs undertaken four to 24 hours after a harder run—is to facilitate recovery from preceding hard training. You hear coaches talk about how recovery runs increase blood flow to the legs, clearing away lactic acid, and so forth. The truth is that lactic acid levels return to normal within an hour after even the most brutal workouts. Nor does lactic acid cause muscle fatigue in the first place. Nor is there any evidence that the sort of light activity that a recovery run entails promotes muscle tissue repair, glycogen replenishment, or any other physiological response that actually is relevant to muscle recovery.

In short, recovery runs do not enhance recovery. Nevertheless, recovery runs are almost universally practiced by top runners. That would not be the case if this type of workout weren’t beneficial. So what are the real benefits of recovery runs? The conventional, muscle-based and energy-focused models of running performance cannot account for the effectiveness of recovery runs. But the new, brain-centered theory can. Here’s how.

There’s a cytokine called interleukin-6 (IL-6) that plays a variety of crucial roles in coordinating the body’s response to tissue trauma and stress, including the stress and trauma of exercise. Large amounts of IL-6 are released into the bloodstream by the muscles during exercise and travel to organs throughout the body, including the brain. Exercise scientists have recently discovered that increasing levels of IL-6 in the brain are a major cause of fatigue during exercise. In a South African study, runners injected with interleukin-6 before a 10K time trial ran a full minute slower than they did when given a placebo. Inside the brain, IL-6 causes feelings of fatigue and inhibits motor impulses sent from the brain to the muscles.

In addition to causing fatigue during running, IL-6 is believed to facilitate many of the body’s adaptations to exercise training, ranging from increased fat burning to greater resistance to muscle damage to improved cognitive function. So the very molecule that causes fatigue during exercise helps you become fitter after exercise.

The primary trigger for IL-6 release during exercise is glycogen depletion. Glycogen consists of long chains of glucose molecules stored in the muscles and liver. It is the muscles’ primary fuel during moderate-to-high-intensity running. Glycogen is also the muscles’ limiting fuel, because it is stored in relatively small amounts, and when its supply runs too low, running performance drops precipitously. Because glycogen depletion produces high levels of IL-6, and because IL-6 coordinates many fitness adaptations to training, it follows that training in a glycogen-depleted state will tend to produce stronger training adaptations (of certain kinds, anyway) than training in a glycogen-replete state.

Recovery runs are exactly that. They occur within 24 hours of hard training, when muscle glycogen is not fully replenished and there is still lingering muscle damage (which is another cause of IL-6 release). Instead of promoting recovery from previous exercise, recovery runs actually enhance running fitness by challenging the runner to perform in a glycogen-depleted state. The notion that relatively short, slow runs can increase the fitness of a runner who also does longer and faster workouts is counterintuitive, but it’s true, thanks to IL-6.

A study from the University of Copenhagen, Denmark, provided some validation for the hypothesis that recovery workouts enhance fitness. Subjects exercised one leg once daily and the other leg twice every other day throughout the study period. The total amount of training was equal for both legs, but the leg that was trained twice every other day was forced to train in a glycogen-depleted state in the afternoon (recovery) workouts. After several weeks of training in this split manner, the subjects engaged in an endurance test with both legs. The researchers found that the leg trained twice every other day increased its endurance 90 percent more than the other leg.

The release of interleukin-6 is probably not the only mechanism by which recovery runs enhance fitness. Research has shown that when athletes begin a workout with glycogen-depleted muscle fibers and lingering muscle damage from previous training, the brain alters the muscle recruitment patterns used to produce movement. Essentially, the brain tries to avoid using the worn-out muscle fibers and instead involve fresher muscle fibers that are less worn-out precisely because they are less preferred under normal conditions. When your brain is forced out of its normal muscle recruitment patterns in this manner, it finds neuromuscular “shortcuts” that enable you to run more efficiently (using less energy at any given speed) in the future. Prefatigued running is sort of like a flash flood that forces you to alter your normal morning commute route. The detour seems like a setback at first, but in searching for an alternative way to reach the office you might find a faster way— or at least a way that’s faster under conditions that negatively affect your normal route.

Another benefit of involving less-used muscle fibers during recovery runs is that these muscle fibers become conditioned to prolonged running. They adapt to the demands placed on them in recovery runs by producing more mitochondria (intracellular aerobic “factories”), capillaries, and aerobic enzymes, so they can be more helpful whenever called upon again.

Finally, recovery runs help you become fitter simply by adding volume to your training without spoiling your key workouts. While hard key workouts boost running fitness more than easier runs individually, high overall running volume is also a powerful fitness booster. The most effective way to enjoy the benefits of key workouts and high running volume simultaneously is to supplement your three weekly key workouts with one or more recovery runs.

The reason high running volume is beneficial is that increases in running economy are very closely correlated with increases in running mileage. Research by Tim Noakes and others suggests that while improvement in other performance-related factors such as VO₂max ceases before runners achieve their volume limit, running economy continues to improve as running mileage increases, all the way to the limit. For example, if the highest running volume your body can handle is 50 miles per week, you are all but certain to achieve greater running economy at 50 miles per week than at 40 miles per week, even though your VO₂max may stop increasing at 40 miles.

The explanation for this linear relationship between running volume and running economy goes back to neuromuscular coordination. Running is a bit like juggling. It is a motor skill that requires communication between your brain and your muscles. Great jugglers have developed highly refined communication between their brain and muscles during the act of jugging, which enables them to juggle three plates with one hand while blindfolded. Well-trained runners have developed super-efficient communication between their brain and muscles during the act of running, allowing them to run at a high, sustained speed with a remarkably low rate of energy expenditure. Sure, the improvements that a runner makes in neuromuscular coordination are less visible than those made by a juggler, but they are no less real.

For both the juggler and the runner, it is time spent simply practicing the relevant action that improves communication between the brain and the muscles. It’s not a matter of testing physiological limits, but of developing a skill through repetition. Thus, the juggler who juggles an hour a day will improve faster than the juggler who juggles five minutes a day, even if the former practices in a dozen separate five-minute sessions and therefore never gets tired. And the same is true for the runner.

The analogy only goes so far, however, because the primary goal of every runner is to push back the wall of fatigue. This requires that runners frequently complete workouts that leave them seriously fatigued. But recovery workouts, which you should always finish feeling no more fatigued than when you started, also help to push back the wall of fatigue by enhancing economy of movement.

Now that I’ve sold you on the benefits of recovery runs, let’s look at how to do them so that they most effectively serve their purpose of balancing training stress and running volume in your training. There are six specific guidelines I suggest you follow.

1. Recovery runs are only necessary if you run four times a week or more. If you run just three times per week, each run should be a key workout followed by a day off. If you run four times a week, you will also do three key workouts, and your fourth workout only needs to be a recovery run if it is done the day after a key workout instead of the day after a rest day. If you run five times a week, at least one run should be a recovery run, and if you run six or more times a week, at least two runs should be recovery runs.

2. Whenever you run again within 24 hours of completing a key workout (or any run that has left you severely fatigued or exhausted), the follow-up run should usually be a recovery run.

3. There’s seldom a need to insert two easy runs between hard runs, and it’s seldom advisable to do two consecutive hard runs within 24 hours.

4. Recovery runs are largely unnecessary during base training, when most of your workouts are moderate in both intensity and duration. When you begin doing formal high-intensity workouts and exhaustive long runs, it’s time to begin doing recovery runs in roughly a one-to-one ratio with these key workouts.

5. There are no absolute rules governing the appropriate duration and pace of recovery runs. A recovery run can be as long and fast as you want, provided it does not affect your performance in your next scheduled key workout (which is not particularly long or fast, in most cases). Indeed, because one purpose of recovery runs is to maximize running volume without sacrificing training stress, your recovery runs should generally be as long and fast as you can make them without affecting your next key workout. A little experimentation will be needed to find the recovery run formula that works best for you.

6. Don’t be too proud to run very slowly in your recovery runs, as Kenya’s runners are famous for doing. Even very slow running counts as practice of the running stride that will yield improvements in your running economy, and running very slowly allows you to run longer (that is, to maximize volume) without sabotaging your next key workout.

 
The following tables show how key workouts and recovery workouts are typically scheduled in the Level 1, Level 2, and Level 3 training plans for all peak race distances in Part II of this book. These general templates show only running workouts and do not include cross-training workouts. The Level 2 and Level 3 plans appear identical because the Level 3 plans include more cross-training workouts that aren’t shown here (as well as more challenging key workouts).

TABLE 7.1 Weekly Workout Template for Level 1 Brain Training Plans

TABLE 7.2 Weekly Workout Template for Level 2 and Level 3 Brain Training Plans