490 BC. The time of year was August. Caveman Doctor was at war with a woolly mammoth, and Greece and Persia were battling each other in Marathon. Greece emerged victorious, and Pheidippides took it upon himself to sprint the nearly 22-mile distance from Marathon to Athens to spread the news.
Upon entering the assembly and shouting, “We have won!” Then, he fell over dead, and so was the story of the first marathon. Clearly people realized that running extended distances could never be healthy, as Pheidippides was a young, healthy, trained soldier and it killed him. As a result, marathon running, jogging, and endurance training, were abandoned as the health risks of continuous exercise were known by all. To celebrate, each year on the third Monday of April, we commemorate Pheidippides and his selfless act of revealing the dangers of long-distance running and endurance training. Since then, we have come to realize the benefits of different forms of exercise like sprinting, walking frequently, and lifting heavy things.
The Pathway to Health…
Unfortunately, none of the above actually happened – although it should have. The history of Pheidippides’ deadly run is likely true, but as is often the case with mankind, we chose to ignore our history and an important life lesson. The third Monday of April each year is celebrated as Patriots’ Day, also known as the day of the annual Boston Marathon. Over the last 30 years, physicians, trainers, and many more have prescribed jogging and endurance exercise as the cure-all for diabetes, hypertension, obesity, and heart disease, among others. Weight training was left to the bodybuilders like Lou Ferrigno, and sprinting was left to the Olympians like Carl Lewis. Jogging and endurance training were prescribed as the pathway to health for everyone else. Those that competed in marathons and triathlons were considered the paragons of health.
Is This Healthy?
You Be the Judge.
In the late 70’s, around the same time our government released the “Dietary Guidelines for Americans,” better known as the “Pathway to Obesity” and our population started to gain immense amounts of weight, recommendations for jogging and endurance training started accumulating and took off over the several decades. These recommendations were based on several studies revealing that basically, the more activity we engaged in, the less chance we had of dying from heart disease1 or cancer;2 and the more intense the exercise, the better.3 Specifically, many studies have shown exercise capacity to be the major predictor of a reduction in mortality through exercise.4,5 In typical American fashion, if increased exercise capacity on a treadmill revealed benefits in health, then excessive amounts of jogging and endurance training must be even more beneficial. Much like the anti-fat campaign, such misguided recommendations were an attempt to promote health but missed the mark (see mu book Misguided Medicine…). The question we forgot to stop and ask ourselves was an important one:
Did we engage in this type of activity for several million years when we roamed the earth? If not, why would it be healthy to stress our body in this manner nowadays?
How Did We Train?
The simple answer is: we didn’t. For millions of years we walked several miles per day in search of food and water, sprinted in short bursts from predators and after prey, and lifted heavy objects when performing manual labor and hunting. Even gathering food required intense climbing, bending, squatting, digging, and lifting.6 This likely did not include extensive periods of running, resembling that on a treadmill or jogging. We never ran marathons, rarely jogged, and likely did not engage in endurance training, especially under the guise of health. Circumstances may have led to exceptions of course. However, it seems like most of the exercise our bodies encountered during their upright evolution involved periods of high intensity activity in short spurts intermixed with lifting of heavy weights and long periods of walking6 – both the antithesis of endurance training and jogging. Unfortunately, our society seems to have reached a paradox: physical activity is decreasing in many, even children;7 however, jogging, an exercise activity previously unseen in our society, has increased markedly in the past several decades.8
The modern-day hunter-gatherers also give a glimpse into past-time activities, as the Ache in eastern Paraguay have been known to walk very long distances in search of food9 intermixed with 20-30 second sprints, resembling that of running wind sprints.6 The women undergo long periods of activity as well when they spend a large fraction of the day moving camp.10 As described by Dr. Kim Hill, the anthropologist who has spent much time with Ache people, they “sprint, jog, climb, carry, jump, etc. all day long.” Interestingly and no surprise, studies were performed on these same individuals revealing elite physical abilities. Even the Maasai continue to walk extended distances, though they are part hunter-gatherers, part pastoral.11
Unfortunately, modern man, under the time constraints of work which often involves little physical activity while sitting at a desk,has replaced the activity of moving often and quickly at times, with long periods of inactivity followed by compensatory long periods of jogging and endurance training.
What Happens to the Body After a Lifetime of Endurance Training?
Those who compete in marathons, triathlons, and other endurance events have been considered the quintessential beings of fitness. However, studying these individuals paints a much different picture, one closer to naked Pheidippides after collapsing, especially when it comes to effects on the heart. Recent data is nearly echoing what Pheidippides showed us some 2,500 years ago. Once again, when we ignore history, our health suffers.
A recent study followed 40 athletes, analyzing several cardiac factors at baseline, following 3-11 hours of endurance exercise (a race), and one week later to assess the effect on the heart.12 The results revealed right heart dysfunction and the release of cardiac enzymes, both in direct proportion to race time. Cardiac enzymes are released from the heart when myocardial cells (muscle cells) are damaged. Basically, the longer the participants trained, the more right heart dysfunction they experienced. This dysfunction mostly resolved within a week, however, and here is the important part, in those participants who chronically engaged in endurance exercise, cardiac remodeling, including fibrosis of the heart occurred.
Extensive studies in runners of the Boston Marathon have analyzed heart function, revealing some remarkable results. To look at this, they studied troponin (a protein attached to heart muscle which is released into the blood stream from myocardial damage during a heart attack) and echocardiograms (ultrasound images of the heart). The echocardiograms done in marathon participants revealed more right ventricular dysfunction with impaired filling of the heart (as it prepares to pump our blood) and a resulting increased pressure on the lungs (pulmonary pressure).13 Several biomarkers were increased as well, and over 60% of runners had significantly increased troponin levels, including 40% with high levels of heart muscle cell death (necrosis) and levels that, had these people presented to the emergency room, they would be considered as heart attack patients!
However, this damage is not only limited to right side of the heart, as studies have shown that prolonged endurance exercise decreases function of the left ventricle as well.14 A similar study showed that left ventricular dysfunction even occurs in triathletes.15 However, a similar study showed that while Olympic athletes fared differently,16 it still occurred in non-Olympic athletes who likely compare with the rest of us.
In fact, another studied showed that 50% of lifelong male athletes, though healthy and asymptomatic, had myocardial fibrosis.17 Fibrosis of the heart was significantly associated with the number of marathons, ultra-endurance activity, and number of years spent training.
Have a Heart, Skip the Marathon
Marathon running has been shown to result in cardiac inflammation and decreased blood flow to the heart, which may explain why runners have an increased risk of heart damage during the marathon. Other studies show that acutely, running a marathon results in enlargement of the right atrium and ventricle with associated dysfunction, along with the release of cardiac troponin I and B-type natriuretic peptide.18 This is, in essence, again similar to what you would find when someone was experiencing a heart attack. Stressing the body has been shown to be beneficial in many ways (as discussed here , here, and here), however, it is difficult to believe that mimicking a heart attack through exercise is advantageous. In fact, excessive stress from exercise has been shown to decrease our body’s natural hormonal response19 as well as damage the autonomic system. This may also account for several of the heart attack deaths during marathons that we hear about on the news often.20
However, injury is not limited to the heart in endurance athletes. While all forms of activity obviously increase the chance for physical injury, studies have shown the risk of sustaining an activity-related injury was proportional to duration of intense physical activity per week.21 It is not surprising that the chronic pounding of endurance exercise wears and tears both the joints and heart. In fact, data shows 38% of runners are injured per year, with a third of these related to knee injuries, and these risks are associated with increased mileage22 and time of activity.23 Similar to heart damage in marathon runners, the total time of extreme activity appears to be key.
Running from Lions and After Prey: Stop Jogging and Start Sprinting
We used to walk most of our day in pursuit of food, shelter, and animals while heavy lifting occurred both during and after these periods of travel, as food and supplies needed to be transported and shelter was built. Recent studies have researched whether the stress and pounding of endurance training can be replaced with training that involves intervals of intense activity, such as sprints, intermixed with less intense periods, just like the Ache people. Such a strategy could effectively provide the potential cardiovascular benefits of exercise, while minimizing the joint and heart damage that result from jogging and endurance exercise. Such exercise also limits the main factor for injury – total time of extreme activity. The drastically smaller amount of time one would have to spend to engage in these activities is the added bonus.
A recent study showed improvements in vascular function with interval training, hinting at a possibility that this ancestral method of “exercise” could provide the cardiovascular benefits of exercise without the ill effects. Sprint interval training showed benefits on muscle health by enhancing its ability to metabolize carbohydrates,24 stopping them from hanging around and increasing blood sugar, insulin levels, and fat production (as already discussed here). Other studies confirm these findings, showing that sprint intervals can provide increased muscle oxidative potential and endurance capacity at a fraction of the time24,25 and physical cost of the wear and tear of jogging.
Taking this a step further, one study directly compared sprinting intervals with continuous running, and sprinting increased insulin sensitivity and decreased blood glucose levels26 over jogging. In the same study, sprinting, but not continuous running, reduced LDL and total cholesterol. However, as you will see below, the benefits don’t stop here.
A common goal of the caveman diet and lifestyle is to limit and fight free-radical attack on the body. This can be done by avoiding excess amounts of carbohydrates and reducing inflammation. High intensity training (via interval training) in rats resulted in a similar benefit, revealing an increase in glutathione peroxidase activity (our body’s free-radical fighting mechanism).27 However, continuous training for 45 minutes did not yield similar results, leaving this advantage for the sprinters and fast movers. While chronic endurance activity induces responses and releases chemicals within the body that resembles that of a heart attack, high intensity training, like interval sprinting increases muscle mitochondrial capacity (mitochondria are the powerhouses of our cells), making them more efficient, improving exercise performance and their ability to use carbohydrates for energy in the form of glycogen, instead of storing extra fat.28 It also increases sirtuin content, which has been shown to extend lifespan in yeast29 (and may be activated by resveratrol in red wine30).
Caveman Doctor thinks Tyson Gay looks a lot more like his ancestors versus triathlon competitors or marathon runners.
The Benefits of Short Interval, High Intensity Workouts and Heavy Weight Training:
- Saves many hours per week versus jogging and endurance training.25
- Increases insulin sensitivity and decreases blood sugar levels over jogging.26
- Is more efficient at increasing exercise capacity and aerobic power.31
- Provides increased fat loss and better physique to look good for cavelady.32
- Enhances muscle aerobic metabolism.33
- Increases in testosterone, growth hormone, and IGF-BP,34 (which fights cancer) while over-training disturbs autonomic function.19
- Increase strength, explosiveness, and performance to run from lions, or sometimes cavelady.35,36
- Reduces wear and tear on your joints and ligaments that happens during long periods of endurance training.
- Results in less neurologic fatigue and risk of injury, i.e. when you hit neurologic failure from extended training, your joints, tendons and ligaments are recruited to carry the load instead of your muscles taking the brunt, resulting in more injuries.
- Provides increased muscle mass, decreased body fat, and less muscle wasting that occurs with endurance exercise.
- Leaves your heart more efficient and requiring less oxygen to function well.37
Just like modern diets that are foreign to our bodies and upon which we cannot thrive, modern exercise is often no different. Injury to the heart and body is not why we exercise and avoiding long duration endurance training may be our best bet to provide us with the benefits of exercise, while minimizing damage to our joints and cardiovascular system. Not to mention the time you will save. A common complaint of healthy eaters and modern cavemen alike is the time that it takes to hunt and gather good food and cook it. Next time you are going on a long run, spend 10-15 minutes running interval sprints instead. Use the time saved to cook up a meal that would make a caveman proud.
Also, keep in mind sprints don’t have to be based on running. Any quick intense activity in cycles can be considered sprinting, including swimming or one of many weight-bearing exercises in the gym. Ten repetitions of 20-30 second spurts of intense activity may work best, whether it is sprinting at the park, or for those of you who don’t want to run (especially in public), try going into the cardio room at the gym, closing the door, and throwing some weights around in similar intervals. I also find that this quick, fast-paced workout is a better stress reliever mentally than the drone of the treadmill or elliptical trainer.
A common theme on this website is that nature and history will guide us to health. Reviewing the activities of our ancestors may provide the greatest insight as to which form of exercise will provide us with the most benefits. Don’t ignore this history. Heed the prophetic message of Pheidippides’s demise and avoid endurance activities.
Every time Caveman Doctor ventures to Washington Square Park to run sprints, or the Schuylkill River trail to walk several miles, he gives his thanks to his ancestors and Pheidippides for paving the way to exercise health. You may also catch him at the gym lifting heavy weights, just like his ancestors setting up camp or carrying their dinner home. However, you definitely won’t catch him jogging for miles, and his knees and heart thank him for that.
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