Friday, August 3, 2007

Training is no guarantee of health

By: Mark Sisson

Let’s get one thing straight right off the bat: Endurance training is antithetical to anti-aging. So it amazes me when guys in their 40s and 50s who are training for a marathon or Ironman suggest that doing so will keep them young. It won’t. You may feel like a stud now with your shaved legs and your magic marker biceps tattoos, but endurance training speeds up the aging process almost as fast as watching TV, drinking sodas and eating potato chips. Actually, in some cases, it speeds it up even faster.

I know, I know, you’ve been told that exercise is the great panacea -- the fountain of youth -- and that the more you do, the greater the benefits will accrue. Well, science has started to prove that concept wrong, and I suspect the evidence in support of my thesis will accumulate exponentially now that the first generation of Frank Shorter "psychophants" has started dropping. There is a middle ground where there's a perfect balance of diet and exercise that will lead to the longest, most productive and "youthful" existence possible. But it certainly isn't found in endurance training. That said, I do think there are ways (some legal, some not) to mitigate the damage and extract the healthiest life possible if you do choose to train long and hard.

First, if I may, a little history lesson:

Humans were just not designed to work for extended periods of time at 80-90% VO2max. Our evolutionary blueprint, the last draft of which was completed well over 10,000 years ago, set us up as great slow-movers and occasional fast sprinters. Our two primary energy systems are: (1) fat-based, which allows for long slow steady walking across the Savannah (or the Queen K after dark); and (2) ATP-based, which gave our ancestors 20 seconds of balls-out sprint speed to escape the charging saber tooth tiger (or let grandma lift the '67 Ford truck off gramps when the jack failed). We just weren't designed to operate at high revs for long periods of time. Doesn’t mean we can't, we can, but it's at an appreciable cost that I will explain shortly. It just means we weren't evolved to. Even our hunter-gatherer ancestors probably relied more on superior tracking skills and walking than they did running for hours or days after their prey. In fact, the energy costs of doing the latter were so high as to almost guarantee extinction. (Imagine your predicament when you run after an antelope for four hours and he gets away. Now you not only don't have any food, you’ve used up all your glycogen and, oops, there’s that frikkin' saber-tooth again, licking his chops.)

But our bodies are among the best in Nature at adapting to hostile environments and self-destructive lifestyles. It's that capacity to adapt that allowed our ancestors to pass along their DNA blueprints to us, but it's also what allows us to today to weigh 500 pounds when we overeat a little, or allows addicts to thrive on a 60 Vicodin a day, when the rest of us would die taking 10. During the Irish potato famine, many went from living on nothing but 14 pounds of potatoes per person per day to living on nothing but seaweed and shoe leather for months. Now that’s what I call adaptation. But, I digress.

Back when the concept of extended games playing was invented it was a natural alpha male thing to want to test the endurance of one guy against another. And because the first real endurance games probably only happened after the introduction of agriculture around 10,000 years ago, you could say that it was largely because of access to these new-fangled high-carbohydrate grains that we could first fully explore our adaptive endurance mechanisms. You could even argue that grains and sugars fueled the endurance fire as our early frat-boy ancestors attempted to one-up each other every generation until today, where we have type-As doing triple-ultra Ironman and Marathon de Sables back-to-back. Sure, they burn a little fat here and there, but most of it is based on a maladaptive second-rate carbohydrate energy system that was never contemplated in the original design prototype! OK, enough endurance history. What does this have to do with aging?

Turns out that carbohydrate metabolism is an inefficient and costly way to locomote, especially if you intend to operate at high revs for long periods of time. Your muscles and liver can only hold 500-600 grams of precious glycogen (stored glucose) at any one time. Even for a well-trained runner, that’s only about two hours worth of fuel when you’re cranking sub-sixes. So it behooves an endurance athlete to consume lots of carbs -- the simpler the better -- and to accelerate the burning of fatty acids if s/he chooses to continue training and racing. And that's where the philosophies of endurance training and anti-aging agree to disagree.

The requisite high intake of carbohydrates to provide fuel requires that an enormous amount of insulin be produced and circulated to help store it. Chronic high blood insulin levels promote inflammation. Anti-aging scientists will tell you that insulin is one of the best markers of longevity in all animals… that the less you produce (type 1 diabetics notwithstanding) the longer you live.

Chronic high-level training naturally depletes glycogen, which causes the body to release the adrenal hormone cortisol to cannibalize muscle tissue in order to help make new glucose (gluconeogenesis). Besides tearing down valuable muscle, chronic cortisol release carries with it a litany of negative effects. It suppresses immune function, which opens the door not only for short term upper respiratory infections, but may leave the door open for longer term, more serious issues (asthma, cancer, heart disease [which we know has a strong inflammatory component]). Chronic cortisol release also reduces calcium uptake by bones, and it's not surprising that so many runner/triathletes -- especially women -- have low bone density. Anti-aging experts will tell you that among elderly, low bone density is a pretty accurate predictor of mortality. Break a hip bone when you're older and your chances of dying skyrocket.

Speaking of cortisol, not only does training and racing tend to produce it, but even the training meals can produce it. A meal high in sugar and other simple carbohydrates can cause a dramatic rise in cortisol (as part of an insulin-adrenaline cascade). That's one reason why sugar is known as a powerful immune suppressor.

The beta-oxidation of fats during heavy training generates oxidative fallout (also known as "free radical damage") at a rate that is often 20 times what you generate at rest. Oxidative damage of cellular constituents such as DNA, proteins and lipids can result in progressive destruction of cells and tissues. This oxidative damage is believed to be a contributing factor to many diseases including cancer, heart disease and aging in general. Your body has natural antioxidant systems designed to keep pace with your normal low-level fat-burning systems (walking and at rest) and even your occasional ATP-based "life or death sprint" systems, but it really wasn't designed to compensate for hours of high-level aerobic performance. Oxidative damage to cellular DNA is usually cleaned up by the immune system, which destroys damaged cells, but if your immune system is compromised, it may set the stage for major problems later on. The cumulative effects of oxidative damage are visible on the faces of many long-time mileage junkies, but it's the damage underneath that most aggressively counters any anti-aging efforts.

Lean mass in general is one major defining predictor of longevity. The concept of dying of "natural causes" is, in reality, better described as "dying from organ failure due to loss of organ reserve and lean tissue." Organ reserve (the functional capacity of any or all organs necessary to support life) and skeletal muscle mass tend to increase or decrease together depending on the stimulus or lack of it. So, as a rule of thumb, anything you do to build muscle generally tends also to build or improve other tissue, including vital organs (heart, liver, lungs, kidneys, etc). Similarly, anything you do to diminish muscle tends likewise to have a negative effect on organ reserve. We call it "atrophy." Of course, the old adage "use it or lose it" has significance here, since it is presumed that by moving about, by doing work and generally being "vital" you give your body a reason to "adapt" to the work. Furthermore, because your muscles are generally fed either directly or indirectly by those organs, they are also called upon to adapt and stay vital. Stay in bed for a few weeks and you'll lose both muscle mass and organ reserve. If you are young, you can build both back with diet and minimal exercise. If you are old, it's often the beginning of the end.

Generally, exercise is a great way to increase muscle mass and, hence, organ reserve. We were, after all, designed to move. The difference is that our DNA blueprints were fine-tuned to have us operating optimally when we walk long distances, sprint like hell periodically, move occasional heavy loads, climb trees and generally tap into our fat-based energy system and our ATP-based energy systems. The benefits of true low level activity are many: We develop an extensive capillary network to bring fatty-acid fuel to each and every muscle cell, we up-regulate the production of fat-mobilizing and fat-burning enzymes which take fat out of storage and present it to the mitochondria for combustion, we improve cardiac muscle efficiency and cardiac capacity and we increase natural internal antioxidant levels. As for the ATP-based system, intermittent heavy loads do increase muscle mass very effectively, also stimulating growth hormone release, as well as improving insulin sensitivity and promoting bone density. The net effect of surviving that run in with a saber tooth tiger was that you got stronger and better adapted to do it again next time.

The problem with many, if not most, age group endurance athletes is that the low-level training gets out of hand. They overtrain in their exuberance to excel at racing, and they over consume carbohydrates in an effort to stay fueled. The result is that over the years, their muscle mass, immune function, and testosterone decrease, while their cortisol, insulin and oxidative output increase (unless you work so hard that you actually exhaust the adrenals, introducing an even more disconcerting scenario). Any anti-aging doc will tell you that if you do this long enough, you will hasten, rather than retard, the aging process. Studies have shown an increase in mortality when weekly caloric expenditure exceeds 4,000.

That's why I stopped racing and training ten years ago and why I prefer hiking, sprinting and weight-training today. But what's a competitive type-A to do if s/he wants to kick age-group butt in Kona and NOT fade away prematurely?

Given carte blanche to take advantage of all that medicine has to offer, I would aggressively consume antioxidants during my training (10-20,000 ORAC units per day), I would increase the amount of healthy fats (omega 3-rich) in my diet to 50% of total calories and I would only consume quality complex carbohydrates during my training. In fact, I would calculate my carbohydrate requirements on a daily basis and not exceed them. I would use simple sugars (e.g., gels) during long rides and races only to the extent they are necessary. That means I would do most of my training without them, saving them for races. I would work closely with a trained anti-aging doctor to monitor my fasting glucose, fasting insulin, free and bound testosterone, liver enzymes, cortisol, DHEA, hematocrit, ferritin and other parameters.

I would incorporate therapeutic amounts of testosterone (yes, I know it's illegal, but I'm giving you the best-case scenario), to balance out high levels of cortisol when I have gone to the well too much. (On a side note, I find it doubly ironic that Floyd Landis was allowed to take thyroid hormone because of his exhausted thyroid and cortisone because of his necrotic hip, but was not allowed to take testosterone during training. If he had been allowed the testosterone, it's quite likely he would not have required the other two meds! And I believe he did not take testosterone).

I would take at least 6 months away from training each year and focus on building lean mass and recovering from the prior season. Under those conditions, I am fairly certain that I could mitigate most of the damage done by any unnatural endurance endeavor I elected to do -- such as IM and marathons -- despite the known consequences.

Now, what does all this mean for the generation of us who bought into Ken Cooper’s "more aerobics is better" philosophy? Is it too late to get on the anti-aging train? Hey, we're still probably a lot better off than our college classmates who gained 60 pounds and can't walk up a flight of stairs. Sure, we may look a little older and move a little slower than we'd like, but there's still time to readjust the training to fit our DNA blueprint. Maybe just move a little slower, lift some weights, do some yoga and eat right and there's a good chance you'll maximize the quality of your remaining years… and look good doing whatever you do.

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