Run for Your Life

by Mark Cucuzzella

  The sugar-burning “gasoline” system (mix of anaerobic and high-end aerobic)

  When you sprint or make an explosive, momentary effort, you are burning glucose, a quickly metabolized, high-octane sugar. The muscles almost instantly convert glucose to ATP and deliver short bursts of high energy. This is comparable to stomping on the gas and using the hybrid car’s gasoline engine exclusively—which can be handy for powering quickly up a steep, short hill to pass a truck.

  This capability has been useful to us throughout our evolution (think fight or flight), but only for about one minute at a stretch. There’s simply insufficient lead time to get a sustained dose of oxygen into the muscles for this instantaneous, on-demand form of energy. And this mostly anaerobic system (it occurs in the absence of oxygen) is limited by the toxic accumulation of acidic by-products—the equivalent of excessive, dark exhaust, in the car analogy. Hard sustained exercise uses the high end of the aerobic system and depletes the sugar/gas quickly and is also “exhaust” heavy.

  The fat-burning “electric” system (pure aerobic)

  To increase endurance and efficiency, on the other hand, we need to transition out of the sugar-burning “gas guzzling” mode, and switch to the more efficient, fat-burning “electric” system. It’s a cherished myth that if you are exercising at your peak efficiency, sugar is the best fuel to keep you going. In fact, fat is a far more useful energy source, because it offers much more ATP per molecule than sugar does. The metabolic by-products (“exhaust”) from burning fat are cleaner, too, resulting in less harmful inflammation. (Ketone bodies are one product of aerobic-fat metabolism, and have been described as a “super-fuel”—a clean source of energy that can be used directly by the brain and muscle.) As long as you’re burning fat, you’ll pass the smog test.

  When driving a hybrid car, you often can’t detect the subtle mixing of gas and electricity. Similarly, your exercising body constantly draws upon a changing mix of fat and sugar. But any vigorous effort lasting more than an hour is best performed in “electric”—aerobic, sustainable, comfortable, fat-burning—mode. When running aerobically on fat, we become resistant to breakdown and can run all day on a minimum of added fuel.

  A full battery wins the long-distance race.

  THE TRAINING ZONES

  When training, racing, or simply exerting at any activity, it is helpful to have an idea of the metabolic “training zone” that your body is operating in. These zones, and the thresholds that demarcate them, aren’t precise. But as you dial in awareness of your exertion level, you’ll be better able to gauge your fuel consumption and how long you can endure at a given level of effort.

  The aerobic zone is the lowest-level training range, in which you are functioning almost entirely aerobically, burning fat. The upper part of this zone corresponds to your maximum aerobic heart rate, and your ventilatory (or aerobic) threshold. Building health and endurance, and density of mitochondria, happens primarily in this zone. Paradoxically, strong aerobic training pushes up your anaerobic threshold (AT, see this page), too, because a well-developed aerobic system is packed with functioning mitochondria and better buffers acidity.

  The aerobic threshold (AeT), or ventilatory threshold (VT), is the mostly imperceptible line dividing the pure aerobic zone (in which you are burning primarily fat for energy) and the glucose-burning zone (in which you are burning the more accessible but far less abundant glycogen and glucose). When you are near this threshold, your exertion is aerobic, with minimal or no anaerobic contribution because you are still using your near-bottomless tank of fat. Your daily training goal is to stay near this threshold while remaining in the aerobic zone. You can use this simple feedback tool: when your respiratory rate picks up, or when you can no longer breathe through your nose, dial down your exertion a notch. (You’ll see this on a group run, for instance, when everyone is relaxed and conversational, then someone picks up the pace and conversation ceases.) Consistently creeping above the AeT/VT can lead to increased fatigue, poor recovery, and overall adrenal stress.

  Between the AeT/VT and anaerobic threshold is the glucose-burning zone, where both aerobic and anaerobic metabolisms are operational. The rate of exertion remains tolerable, which means that acidity is buffered and doesn’t accumulate in the system. Racing and periodic workouts in this zone can work for those who are in excellent aerobic health. Many people routinely train in this zone, yet doing so for extended periods is not compatible with building health and endurance.

  The Training Zones

  At the top, at the highest level of exertion, are the anaerobic threshold and the anaerobic zone. When the level of exertion surpasses the anaerobic threshold (AT, also known as the lactate threshold), the body cannot buffer the acidity, and acid begins to accumulate in the muscles. When you’re out of shape, you may reach this threshold quickly, even during a slow jog. The AT of elite athletes, by comparison, is close to their maximum level of exertion, meaning that they can operate at a high level of performance and still remain just below their AT. Training above the AT is difficult and stressful. (For performance athletes, training in the anaerobic zone can be useful at times, but the small increment of fitness they gain can come at the cost of aerobic development and risk of overtraining and injury.)

  In summary, training constantly in the upper zones—above the AeT/VT—can be harmful. We have recently become aware that years of high-intensity training increase the risk of atrial fibrillation, right heart failure, and myocardial fibrosis. Humans, in order to survive, were designed to move efficiently and comfortably over long distances, with occasional bursts of speed. We weren’t designed to run ten hard miles every day at an anaerobic threshold pace.

  SO, WHAT DOES THIS MEAN FOR HOW WE EXERCISE?

  As you exercise and train, you can learn to sense which zone you are in and which threshold you might be near. When the blood glucose and muscle glycogen level—the gas tank—is depleted, we crash, or “bonk,” as runners say. The body signals the brain (which strives to maintain a constant blood sugar level) to tell the runner to slow down, stop, or take in nourishment immediately.

  Many of us run too hard, yet we get away with it by trying to replenish our easily accessed but quickly depleted glycogen gas tanks in the liver and the muscles. For the fatigued or bonked runner, however, topping off the tank with more sugar, followed by high levels of effort, only repeats the cycle of eating, exertion, and exhaustion. By analogy, it’s better to feed a hot fire by throwing on a log (fat) than by constantly feeding it paper or twigs (sugar).

  Months and years of aerobic training and proper diet can make you a “better butter burner”—as in fat burner. One common measure of cardiorespiratory fitness (especially endurance) is an individual’s maximum rate of oxygen consumption, or VO2 max, which can be measured during exercise of increasing intensity. What’s interesting is that two people with the same measured VO2 max—two runners with nominally the same level of maximum endurance—can exhibit, in running lab tests, a marked difference in their abilities to burn sugars or to burn fats. “Fat adapted” athletes can run close to their AT while still burning fat while sugar-dependent athletes switch to sugar at low intensities. In endurance training sessions or long events especially, those who have “trained” their enzymes and metabolism to burn long-lasting fat calories will pull away from those whose bodies have become dependent on stored and ingested sugar. I encourage you to visit runfo­ryour­lifeboo­k.com for my discussion about this, “Burn Fat for Health and Performance: Better Butter Burner,” where I share the results of my 2017 test.

  POWER CENTERS AND PATHWAYS

  To successfully build our endurance engine (and boost overall health), we need to increase the density of the mitochondria and capillaries in our muscles. This is done through consistent, sustained exercise of light to moderate intensity, and efficient delivery of oxygen to the muscles.

 
Our bodies can burn glucose and glycogen for only a short period. But most of us, even if our body profile appears lean, have a functionally limitless reserve of fat. We can tap into fat metabolism by slowing down and training within the pure aerobic zone, while maintaining a diet full of healthy fats.

  The burning of fat greatly boosts the efficiency of our mitochondrial machinery. Accessing fat provides the environment for building more mitochondrial power centers and more capillary pathways, meaning that even more fat can be metabolized for training runs and races—and for the military’s 1.5-mile fitness test.

  The physiology and chemistry is complex, but the practical implications for us are straightforward: the more capillaries and mitochondria we have, the more ATP they produce and the stronger and faster the muscles contract without fatiguing. When you create the demand for long-term performance, the body responds by creating the machinery. This is the hybrid’s electric engine: never empty and always recharging, as long as you eat healthy fats and maintain a comfortable pace. In the car analogy, you are morphing from a Charger to a Prius, and ultimately to a Tesla, as your electric engine grows.

  The long-term effect of comfortable endurance training: more energy-delivering capillaries and mitochondria expand and perfuse into the muscles.

  Running coach Arthur Lydiard was aware of this. His method of training the best middle- and long-distance runners began with months—even years—of aerobic training. His runners launched the foundational part of their training regimen with easy, aerobic runs—mostly in the comfortable, fat-burning aerobic zone. His 800-meter specialists trained by going on twenty-two-mile runs, and they racked up a hundred miles a week. The reason was simple: he wanted his runners to build a massive and resilient aerobic system. As competitive events approached, he turned up the intensity, by gradual and measured increments, until the runners were pushing their maximum capacity.

  For most athletes, six weeks of high-intensity training before an event seems to be the maximum tolerated training period before their level of performance peaks and then may even start to decline as the runner begins to overreach and overtrain. (See chapter 11 on recovery to better understand the important role that rest plays in building strength and endurance.) Muscoloskeletal injury is also associated with high-intensity training over extended periods.

  I’m not suggesting that you run twenty-two miles at a pop, or a hundred miles a week, but these principles still apply to almost all modern training programs. A carefully gauged progression works to optimize the body’s daily eustress—the optimum dose of physiological stress that builds health and imparts a feeling of fulfillment. At this moderate level of stress, neovascularization and biogenesis occur in the heart, too, whereby areas of the heart grow new blood vessels and the cells remodel, and more mitochondria and capillaries are formed. This results in a richer network for oxygen and nutrient delivery.

  In the year 2000, I began to experiment with pure aerobic training speeds, and as I slowed down, the faster I got—at the same level of easy effort. I began by running ten-minute miles at a heart rate of 150. Six months later, I was running six-minute miles at the same heart rate. That fall, I entered the thirty-thousand-runner Marine Corps Marathon, and finished third, without having done any hard running or speed work.

  At the finish line, I was surprised by an unusual sensation, compared with previous races: I felt that I could turn around and do it again. It’s common for runners to feel, after training in the aerobic zone for a few weeks, that they have more energy after their workout than when they began. Try it yourself.

  In the early 1960s, Lydiard introduced “jogging” to New Zealanders, and eventually to the world. He also developed the first cardiac rehabilitation program that included jogging as part of its therapy. He knew that relaxed movement was the secret to recovery from heart disease, and he encouraged cardiac patients to build up to thirty minutes of jogging a day (at a conversational pace), over a period of several weeks to months. At that time, by contrast, the U.S. medical establishment was focused on resting the body. Since then, we have learned that bed rest, especially, is very damaging to the heart, and we have adopted Lydiard’s principles. The thirty-minute a day jogging goal for cardiac rehab is now the foundation of the Physical Activity Guidelines for Americans.

  In my medical practice, too, I encourage my heart disease patients to slowly ramp up to a jogging pace. Following a heart attack, the heart loses some of its contractility and efficiency. But aerobic training boosts the capacity of the body’s muscles by up to 400 percent, which means that the heart needs to work less for any given activity.

  Take the case of local runner Mike Foster, a young father of three. At age thirty-eight, Mike was living a healthy, athletic life. He didn’t smoke, drank little alcohol, and ate healthfully, but he did have a family history of heart problems. In January 2014 he played a game of basketball and felt some pain in his chest (which he assumed was from an elbow in the ribs) and shortness of breath (which he thought was from being winded, following a two-week vacation).

  Mike had suffered a heart attack. He promptly underwent quintuple bypass surgery. Afterward, he committed himself to rehab, and set his sights on entering the Freedom’s Run 5K in October of the same year—and he completed it. One year later, following twelve more months of low-intensity training, he broke the tape of the Freedom’s Run marathon. His kids were waiting and cheering at the finish line.

  By focusing on comfortable training and overall health, Mike no longer has markers of progressive heart disease. He—and increasingly others—have shown that whole body conditioning may be the best form of cardiac rehab.

  SLOW AND STEADY WINS THE RACE…

  Many believe that high-intensity, push-the-envelope workouts make you stronger and fitter than low-intensity workouts. This may work temporarily, but can create a toxic, acidic environment in the muscles, inhibiting the aerobic development that we seek.

  Less acute, but just as damaging in the long term, is falling into the “black hole” of training. This comes from consistently training above your aerobic threshold, and not allowing sufficient time for recovery. Many of us do this, and wonder why our performance declines. It distresses me to see people destroying themselves in brutal, intense daily workouts in the name of athletic excellence (or to “make up for lost time”). We need to slow down in order to speed up, and we need to run with joy. As the minimalist running tribe leader and friend Barefoot Ted says, “Don’t practice pain. Practice pleasure.”

  There’s no hurry. We are training for the rest of our healthy lives.

  Slow and steady wins the race.

  DRILLS

  To determine the best, sustainable level of exertion for building the aerobic (“electric”), fat-burning engine, it’s best to have a trainer or master teacher. But a heart rate monitor can work, plus some simple measurements and record keeping. Once you reach a fitness plateau, you shouldn’t even need these.

  1. Determine your maximum aerobic heart rate

  There are several methods for finding your maximum aerobic heart rate (MAHR)—the sustained rate that will best build your endurance engine. This heart rate (or range, within a few beats per minute) is most easily and safely determined by using the “180 Formula,” developed by Dr. Phil Maffetone in 1982. Despite some differences, other methods for calculating this work fine—most of the time. The Karvonen formula and the Friel method, based on lactate threshold, work well, but deriving MAHR from them is more complicated.

  Elite athletes Mark Allen and Mike Pigg, among many others, have successfully used the 180 Formula for building a solid foundation for health and world-class performance, and for extending their race careers. I’m confident that you’ll discover what we have: although your heart rate remains in check over the weeks and months of training, your endurance, your feeling of well-being, and your speed will improve.

  The 180 Formula

  Subt
ract your age from 180 (180 – age). This gives you a baseline beats per minute (bpm).

  Then modify this number by selecting adjustments that match your health profile:

  If you have a major illness (heart disease, high blood pressure, etc.), are in recovery from an operation or hospital stay, or are taking medication, subtract an additional 10 bpm.

  If you have never exercised, have been training inconsistently, have not recently progressed in training or competition, are injured, or get more than two colds or bouts of flu per year or have allergies (or are subject to a combination of these), subtract an additional 5 bpm.

  If you’ve been exercising regularly (at least four times weekly) for up to two years without any of the problems listed above, keep the number at 180 minus age.

  If you have been competing for more than two years without any of the problems listed above, and have improved in competition without injury, add 5 bpm.

  For example, if you are thirty years old and have not been training consistently, then your MAHR would be:

  180 – 30 = 150, then 150 – 5 = 145 bpm

  In my case, I am fifty-one years old and work out at least four times per week, and I’ve been healthy, so I add 5 bpm to the raw number of 180 minus my age. I end up with a MAHR of 134 bpm.

  Whatever figure results from this calculation, this maximum aerobic heart rate generally falls within the range recommended by exercise physiologists as a safe aerobic training heart rate: 60 to 80 percent of one’s maximum heart rate—the highest rate that your heart should normally reach during extended physical exertion. The 180 Formula is slightly conservative, and therefore especially good if you are new to running, are recovering from an injury, or don’t feel sufficiently fit to take on the high-intensity run.