The Primal Blueprint (37 page)
Read The Primal Blueprint Online
Authors: Mark Sisson
While you can benefit from low-intensity aerobic exercise almost indefinitely (e.g., hiking the Pacific Crest Trail or Appalachian Trail all summer is pretty darn good for your overall health), you can obtain outstanding health and fitness benefits by engaging in a moderate amount of low-intensity aerobic movement (hike, walk briskly, cycle gently—or jog if you are really fit). Everyone should shoot for a bare minimum of two hours of low-intensity aerobic movement per week. Obviously, Grok did much more than this and ideally we would, too. I’d consider three to five hours per week an optimal range for most people with busy lives. If you can manage a single long hike on the weekend and a few short walks or cardio machine sessions during the week, you will dramatically reduce your risk of heart disease (in comparison to being sedentary), support optimal metabolism, better control your weight, and, in conjunction with the other two types of workouts, achieve Primal Fitness.
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The aging process should really be called the “process of physical decline largely due to inactivity.”
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Remember that these recommendations are averages. I will occasionally go for extended periods of time (for instance, when I travel for business or pleasure) doing much less exercise than normal. I suffer no ill effects, experience no change in body composition, and invariably pick up right where I left off when I resume normal training. At other times, when the stars align and I have the free time, I’ll benefit greatly from doing vastly more than the recommended average (e.g., when going on a backpacking trip or another active vacation).
My definition of
low intensity
is working at 55 to 75 percent of maximum heart rate (I will discuss in detail just what this means shortly). With this casual aerobic exercise, your heart and other energy systems work a little harder to handle the extra fuel
and oxygen delivery demands, but not so much that you are overstressed. The specific biochemical signals created by this low-level aerobic activity produce numerous health and fitness benefits:
Improved Fat Metabolism:
Low-level aerobic exercise trains your body to efficiently utilize free fatty acids for fuel, a benefit that is realized 24 hours a day, with a higher metabolic rate and a preference for fat over glucose (provided you follow the
Primal Blueprint
low insulin–producing diet). Low-level aerobic exercise has also been shown to help balance blood sugar levels and regulate appetite.
Improved Cardiovascular Function:
Aerobic exercise increases your capillary network (blood vessels that supply the muscle cells with fuel and oxygen), muscle mitochondria, and stroke volume of your heart (more blood pumped with each beat) and also improves oxygen delivery by your lungs.
Improved Musculoskeletal System:
Aerobic exercise strengthens your bones, joints, and connective tissue so you can absorb increasing stress loads without breaking down. This is critical to your ability to perform and recover from the occasional intense workouts that are a key component of the
Primal Blueprint
program.
Stronger Immune System:
Aerobic exercise enhances immune function by stimulating beneficial hormone flow and building a more efficient circulatory system.
Increased Energy:
Low-level aerobic exercise leaves you energized and refreshed, rather than slightly fatigued and depleted from more intense workouts.
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Walking is the best possible exercise. Habituate yourself to walk very far. —
Thomas Jefferson”
My discussion about Law #3 repeatedly references the optimal low-level exercise zone of 55 to 75 percent of maximum heart rate. Fifty-five percent of maximum reflects the bare minimum exertion level to legitimately consider your effort “exercise.” An unfit person can reach this walking to the mailbox. If you aren’t familiar with heart rate training, you may be surprised to discover just how easy even the upper limit of 75 percent of maximum heart rate is. At this pace, you break a light to moderate sweat, can easily converse without getting short of breath, and finish feeling refreshed and energized instead of slightly fatigued and hungry, as you might after more strenuous workouts.
The increasingly popular (and affordable—an excellent model can now be had for about $70) wireless heart rate monitors can help you accurately determine your exercising heart rate to ensure you stay in optimal range. While I won’t say monitoring your heart rate is mandatory, this is one area where technology can play a valuable role, especially to ensure the success of your low-level workouts. Even for experienced athletes, it’s quite easy to exceed 75 percent (and thereby sabotage the benefits of your session) because perceived exertion at that level is so minimal.
The most accurate way to determine your maximum heart rate (and thus calculate your numeric ranges for your 55 to 75 percent exercise zone) is with a maximum heart rate test. No fancy laboratory wires needed; you simply warm up, exercise all-out for a couple of minutes and then sprint the last 15 seconds and note your heart rate (or have someone note it for you if you become cross-eyed…or horizontal!). All kidding aside, conducting a max heart rate test requires full medical clearance from your physician and is best done under supervision from a fitness professional. The next best option is to use these formulas to generate an accurate estimate for the vast majority of the population:
• 220 – age = estimated maximum heart rate for males
• 226 – age = estimated maximum heart rate for females
For example, Ken Korg at 40 would have an estimated max of 180 beats per minute (220-age 40). His low-level aerobic workouts should thus be conducted in a heart rate range of 99 beats per minute (180 max × 55 percent) to 135 beats per minute (180 max × 75 percent). The “Primal Fitness Heart Rate Zones” sidebar will help you understand the perceived exertion equivalents to various heart rate zones, as well as the metabolic effects of working out at these intensities. The workout descriptions in each zone based on fitness level are purposefully vague and are meant just as a rough guideline.
Heart rate training individualizes your experience to ensure you get an optimal workout, particularly when you consider the benefits of staying under 75 percent versus the drawbacks of exceeding 75 percent routinely. This critical “individual” element—one that can make or break your entire exercise program—has long been ignored by group class instructors, Team in Training coaches, and other social or competitive workout groups. Generally speaking, asking a class or group of workout partners to keep pace together is a recipe for failure,
for all but the fittest members of the group
. Sure, the camaraderie aspect is motivating and enjoyable, but those with inferior conditioning will become overstressed. There are many ways to still achieve a beneficial group workout (i.e., with each person staying in the optimal heart rate zone) with exercisers of disparate fitness levels, including something as simple as having the faster athletes loop back time and again to retrieve slower members of the group.
The Primal Fitness Heart Rate Zones
20 to 30 percent of maximum: resting heart rate for the extremely fit athlete
. Athletes have a higher stroke volume (more blood pumped per beat) than an unfit person. In my marathon days, my resting heart rate was 38 beats per minute. So much for astronaut Buzz Aldrin’s quote about not doing exercise because “the heart only has so many beats and I don’t want to waste any!” The finite capacity of the heart is literally true, but a fit person will save about 72,000 beats a day, 26 million over a year, and a couple of billion over a lifetime.
40 to 50 percent of maximum: resting heart rate for the unfit person
. The average resting heart rate for adults is 72 beats per minute. Smokers and completely sedentary folks can have resting heart rates that exceed 100 beats per minute. (Lance Armstrong can ride in the pack at 25 mph during the Tour de France at about this rate!)
55 percent of maximum: lower limit of zone for Law #3, Move Frequently at a Slow Pace
. This is the minimum heart rate for an activity to be considered a workout.
Energy source:
primarily fat.
Fit person:
slow to medium hike, slow bike ride, very easy to easy cardio machine.
Unfit to moderately fit person:
casual walk around the block.
75 percent of maximum: upper limit of zone for Law #3, Move Frequently at a Slow Pace
. This is the optimum heart rate for maximum aerobic benefits to occur with minimal stress response or glucose metabolism.
Energy source:
still primarily fat.
Fit person:
vigorous hilly hike, moderately hilly bike ride, medium-intensity cardio machine, medium intensity group gym workout, or slow to medium jog.
Unfit to moderately fit person:
slow to medium hike, minimal to moderately hilly bike ride at slow pace, easy to medium intensity cardio machine, easy to medium intensity gym workout, or very slow jog.
80 percent of maximum: upper limit of zone for Law #3, Move Frequently at a Slow Pace—
for accomplished endurance athletes
. With an excellent aerobic base present, 80% workouts will still rely primarily on fat metabolism with minimal stress response.
85 to 90 percent of maximum: Chronic Cardio “no-man’s-land.”
These workouts stimulate anaerobic metabolism with glucose as the preferred fuel, lactate accumulation in the bloodstream (waste product from insufficient oxygen that causes the familiar “burn” and postexercise soreness), and excessive cortisol production.
Energy source:
primarily glucose
Fit person:
brisk pace or hilly bike ride, vigorous cardio machine or group gym workout, brisk paced run
Unfit person:
vigorous hilly hike, medium speed or moderately hilly bike ride, medium to vigorous intensity cardio machine, medium to vigorous intensity group gym workout, or slow to medium jog. Intensity too high to be considered aerobic but too low (or too lengthy in duration) to be considered an effective sprint session. Occasional sustained workouts in this “race pace” zone can produce outstanding fitness benefits; damage occurs when these cardio workouts are conducted too frequently (i.e. Chronic Cardio).
90 to 100 percent of maximum: high-intensity zone for Law #5, Sprint Once in a While
. This is the optimal zone for occasional brief, all-out efforts. These workouts build muscle, support enhanced organ function, accelerate metabolism, and delay aging via the “use it or lose it” principle.
Energy source:
glucose (for sprints over 30 seconds), lactate (8-30 seconds), or Adenosine triphosphate (“ATP”; for efforts under 8 seconds). Cortisol is released briefly in line with the genetic fight-or-flight response.
In contrast to the comprehensive benefits of a frequent, comfortably paced exercise, getting more serious about working out can really mess you up if you have a flawed approach. Chronic Cardio at heart rates above 75 percent and up to 95 percent of maximum places excessive stress on your body to which you are not genetically adapted. I’d estimate that the vast majority of folks you see working out on cardio machines, jogging through the neighborhood, or keeping pace in the group class are exceeding 75 percent (often by a wide margin) for the duration of nearly every session.
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Chronic Cardio—a program I followed for nearly 20 years as a marathoner and later as an ironman triathlete—is bad for your health, period
.
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While an aerobic workout at the typical intensity of 75 to 95 percent might not feel terribly difficult at the time, a sustained pattern of Chronic Cardio can lead to numerous problems with metabolism, stress management, immune function, and general health. As exercise intensity increases, your preferred fuel choice shifts from primarily fat at intensities below 75 percent (fat burns well in the presence of oxygen, and supplies are abundant—even in the skinniest marathoners!) to an ever-increasing percentage of glucose (quicker and easier to burn when oxygen is lacking due to your quickening pace).
A routine of Chronic Cardio requires large amounts of dietary carbohydrates each day to support it. While the risks of excess fat storage and hyperinsulinemia (overproduction of insulin) are moderated somewhat by a heavy exercise schedule, they are still significant because of your altered dietary habits throughout the day. When muscles are depleted of glycogen (remember, stored glycogen is converted back into glucose for exercise fuel), your brain sends a powerful signal to replenish with quick-energy carbohydrate foods. Our brains have a tendency to tell us to overcompensate by eating a little too much. This is a genetically programmed survival adaptation against starvation risk, handed down to us from Grok. If you are looking to reduce body fat primarily through
vigorous cardiovascular exercise (as Conventional Wisdom promises), you are quite likely to fail unless you slow down your pace and alter your diet to limit your carb intake.
Besides the weight-loss challenges, Chronic Cardio increases the production of cortisol (in all but the most genetically gifted endurance athletes), which breaks down muscle tissue and suppresses production of key anabolic hormones, such as testosterone and human growth hormone. This hormonal imbalance caused by overexercising contributes to fatigue, burnout, immune suppression, loss of bone density, and undesirable changes in fat metabolism. Furthermore, the stress of Chronic Cardio increases systemic inflammation (a strong contributing factor to heart disease, cancer, and nearly all other health problems) and increases oxidative damage (via free radical production) by a factor of 10 to 20 times normal. This can lead to acceleration of the aging process. It’s ironic that many in their 40s and 50s start engaging in marathon or triathlon training in hopes of improving health and delaying the aging process, when, quite often, it has the exact opposite effect.