People are attracted to weight training for various reasons. Some lift weights to assist them in other sports; for example, to increase muscular strength and prevent injuries. Others lift for competitive reasons, such as Olympic weightlifting, powerlifting or bodybuilding. Still others just want to look good, trim and muscular throughout their lives. While sensible bodybuilding exercise offers significant advantages for anyone, regardless of goal, it's particularly beneficial for those over age 40.
That relates to the use-it-or-lose-it principle, which simply states that whatever the body doesn't use recedes with time. The most evident example is the aging process. Aging is inevitable, but the rate at which you age is controllable to a large extent. Degenerative diseases associated with aging, such as cardiovascular disease and cancer, aren't inevitable. They can largely be controlled by avoiding known risk factors while staying healthy through regular exercise and proper nutrition. In short, whether you end up decrepit or in good physical condition is in your hands.
Although scientists give us many definitions of aging, perhaps the most succinct is that offered by Richard A. Miller, a researcher of the aging process at the University of Michigan. Miller says that aging 'is the process that converts fit adults into frailer adults with a progressively increased risk of illness, injury and death.' While aging cannot be eliminated (except for the unacceptable alternative of dying young), emerging therapies offer the promise of staying young as long as possible.
The actual cause of aging is still a subject of debate among gerontologists, or scientists who study the aging process. It's far more complex than most people imagine and involves both lifestyle and genetic factors. The influence of genetics is exemplified by some people who live to 100 or beyond. Many of them come from families whose members are long-lived. A classic example is Jeanne Calmet, a French woman who was born on February 21, 1875, and died on August 4, 1997. Both of her parents lived into their 90s, although her own children died relatively young. Most aging experts say that genetics accounts for only 30 percent of longevity.
Currently, the only scientifically plausible method of slowing the aging process involves calorie restriction'but that alone won't do it, as any observation of many third-world nations clearly shows. People in such poor countries eat few calories but have shorter-than-average lifespans due to such factors as disease and malnutrition. To be effective, low-calorie diets must be accompanied by optimal nutrition, or, as the foremost advocate of calorie restriction, Roy Walford, M.D., called it, CRON (caloric restriction with optimal nutrition).
As to how cutting calories works to delay the aging process, no one seems certain. One prevalent theory is that it slows every major process in the body, including those that produce free radicals. Free radicals are products of oxygen metabolism that wreak havoc in the body by attacking vital structures such as nucleic acids and cellular membranes.
In fact, most theories of why we age involve some aspect of out-of-control free-radical activity. It's implicated in the causes of not just aging but also every other degenerative disease, including cancer and cardiovascular disease. Anything that helps control those metabolic marauders known as free radicals should help slow the aging process.
The body has built-in systems to help defuse rampant free-radical activity. They consist of various enzyme systems, such as superoxide dismutase, catalase and glutathione peroxidase. Significantly, as is the case with many other enzymes in the body, those protective enzymes are activated by nutrients. Superoxide dismutase needs the trace minerals zinc and manganese to work properly. Manganese activates the superoxide dismutase found in the mitochondria portion of cells, where fat is burned and energy (as ATP) is synthesized.
The mitochondria, which depend on oxygen to produce ATP and burn fat, are also the site of the greatest release of free radicals. An emerging theory of aging is that damage to mitochondrial function due to excess free radicals eventually leads to the destruction of cellular mitochondria. Since the mitochondria are the sources of cellular energy, without them cells don't have the energy to engage in processes essential to their existence, such as repair of nucleic acids needed for cellular replication. DNA, a vital cellular nucleic acid, is itself subject to damage by free radicals, an effect that can lead to cellular mutation and cancer.
The prevailing theory about the free-radical-induced aging process, which was originally formulated in 1956 by Denham Harmen, is that the body's natural inherent antioxidant protection is reduced with age, leaving a person subject to oxidative damage. Even exercise, which involves increased use of oxygen, initially increases free-radical production. Some studies show that the body deals with that by also increasing the activity of its built-in antioxidant systems, such as the superoxide dismutase system. Other studies show that the body's built-in antioxidant protection is overcome by the extent of oxygen use during exercise.
From a practical point of view, you have two likely methods of extending youth and delaying the aging process. One involves calorie restriction; the other involves using antioxidant food supplements, such as various vitamins, minerals and other nutrients, to bolster existing antioxidant systems in the body. The problem is that many of the effects of calorie restriction aren't conducive to building muscle. Does that mean you have to make a choice between looking good and dying relatively young or looking scrawny and living longer?
Is Calorie Restriction the Answer?
The origin of caloric-restriction theory, or CR, began in 1935, when a researcher named Clive McKay from Cornell University found that lab rats deprived of calories lived up to a third longer than other lab rats that were allowed to eat as much as they wanted. Roy Walford, a pathologist at UCLA, extended the CR research beginning in 1972 and eventually showed that CR slowed aging in a wide variety of species, from rats to fish, worms and flies, among others. The typical reduction in such studies involved subjects getting 30 to 60 percent fewer calories than they were eating before. While the results with those varied species appeared to point to a definite beneficial effect of CR, the question remained as to whether it offered similar life-extending benefits to humans. Since a human study wasn't possible, the next best thing was to use mankind's closest relative, the monkey. The studies began in 1987 and 1989 at the National Institute of Aging and the University of Wisconsin.
ALL While the final results won't be available for another 20 years or so, the preliminary results show that the rhesus and squirrel monkeys that are eating an average of 30 percent fewer calories than other monkeys are aging slower. They handle glucose better and show decreased insulin levels and increased insulin sensitivity. Those markers for aging all are indicative of a decreased incidence of diabetes.
Diabetes is considered an aging-accelerated disease, since the inability to dispose of excess glucose that's characteristic of diabetes causes glucose to wind up in places it shouldn't be, such as interlaced with protein structures. That process, known as glycation, leads to the stiffened connective tissues commonly seen in older people. The good news is, there are some drugs that may break up such glucose-and-protein crosslinking, and nutrients such as alpha lipoic acid may help prevent it too.
The monkeys on the CR regimen are also showing less incidence of cancer than the other monkeys. That's significant because cancer incidence increases with age. It's thought to occur due to an impaired immune system or to the effects of free radicals on cellular structures. Both are considerably blunted by CR. Mice studies also show that CR may help block cancer by decreasing insulinlike growth factor 1 (IGF-1). While local IGF-1 synthesized in muscle helps to foster muscular repair after exercise, systemic IGF-1 promotes cellular growth, including that of tumors.
On a genetic level, a study published in the August 27, 1999, issue of Science found that CR blocked 84 percent of the activity of genes that trigger cellular aging. Other genes, such as those governing such beneficial processes as response to overheating, DNA repair and oxidative stress, doubled in activity after a CR eating plan.
Those were all animal-based studies, however. CR proponents point to two pieces of evidence to bolster their assertion that CR is the best way to forestall the aging process. One involves people living on the island of Okinawa, near Japan, who show a 40-fold increase in their odds of living to 100 over other people. Their diets average only 1,100 calories a day, but they appear to thrive.1
The other case involves an ecological experiment funded by Texas oil billionaire Ed Bass. Called Biosphere-2 (Biosphere-1 is Earth), it was a three-acre, seven-million-foot enclosed ecological domed space located just outside Tucson, Arizona. The biosphere was supposed to simulate how a colony living in outer space might survive and thrive, and it featured several types of habitats, including a rain forest, savanna, desert, ocean, marsh, agricultural station and living quarters. Four men and four women, including Roy Walford, allowed themselves to be sealed into Biosphere-2 from 1991 to 1993.
Several unforeseen events occurred, and the people living in the biosphere were forced to live on a CR diet, averaging about 1,800 calories daily. That resulted in an average weight loss of 18 percent in the men and 10 percent in the women. Their diet also led to reductions in resting glucose, insulin and cholesterol levels; however, when they emerged from the dome in 1993, most of them looked more haggard than youthful. The Bodybuilding Plan
The good news in terms of CR's implications for bodybuilding is that animal studies show that it helps preserve youthful-appearing muscles. In a study of rats reported in the June 1997 issue of the FASB journal, a diet that restricted calories to 35 to 50 percent of normal led to a prevention of age-related muscle fiber loss and decreased muscle mitochondrial damage due to oxidation effects. The rats in the study began the diet at the human equivalent of middle age.
A rat study published in the journal Biology of Sport in 1995 found that rats on a typical CR regimen of 30 percent reduced calories that exercised for 30 days showed decreased growth and decreased liver and muscle glycogen content. Even worse, they showed decreased activity of the enzymes used in fat oxidation. The rats did only endurance, or aerobic, exercise, which appeared to promote catabolic processes in muscle when combined with significantly reduced calories.
A recent study featured 13 men and 11 physically fit women who reduced their required daily caloric intake by 750 calories, 60 percent of which came from carbohydrates.2 They engaged in treadmill running during the two-week study, and 61 percent of weight loss during that time consisted of lean tissue mass along with increased nitrogen loss, which points to muscle protein breakdown. Despite being in a clearly catabolic state, subjects in the CR group showed no loss of muscle strength, and they had increased muscle endurance.
The picture changes, however, with weight-training exercise. Numerous studies have shown that animals can increase muscle size even on a starvation diet, provided some form of weight resistance is placed on muscles. A recent rat study showed that while overloaded muscle is protected by weight training during calorie restriction, fast-twitch muscle'the type most prone to growth'is most adversely affected by significant drops in calories, while slow-twitch, or endurance, muscle is comparatively spared under such conditions.3
A study of women who went on a reduced-calorie diet compared groups who lifted weights with those who only dieted.4 Not only didn't the women who lifted and dieted lose any muscle, but they actually gained muscle mass.
One scientist who has studied the effects of CR in rats and other animals found that reducing calories by only 10 percent but combining the diet with weight-training exercise showed the same beneficial effects as those seen in rats who didn't exercise but consumed a 30 percent CR diet. That's good news, since even staunch advocates of CR admit that few people have the willpower to follow a 30 percent CR diet for the rest of their lives'however short or long that may be. Several people have followed such a regimen for more than 10 years, and judging by photos, none made a dent in the aging process. They all looked skeletal'nary a muscle anywhere. On the other hand, none of them lifted weights. One known effect of extended CR is an increase in cortisol'which is catabolic to muscle.
You may eventually be able to cull the benefits of CR without the pain. Drugs that mimic the effects of CR are currently in experimental stages, and preliminary studies with animals show that they produce the same effects as CR without the hunger or the pain. One compound in particular, 2-deoxy-D-glucose, enables rats to eat as much as they please yet experience all the beneficial effects of CR. The problem with that compound, which is nothing more than glucose with two missing oxygen atoms, is that it's a bit toxic in large doses. But continuing research will likely yield other formulas that will provide similar effects with less toxicity.
One thing to keep in mind is that CR alone can be dangerous if you don't take in enough essential nutrients. Even CR advocates like Roy Walford advise taking plenty of vitamins and minerals. Walford's Biosphere-2 diet consisted of 76 percent carbs, 12 percent fat and 12 percent protein'a prescription for muscle catabolism. Anyone engaging in weight training would be well advised not to curtail protein intake, even if you're contemplating a modified, or 10 percent, CR diet.
Since one of the primary mechanisms thought to underlie the benefits of CR is a decrease in oxidation, a primary cause of aging, it's also prudent not to skimp on antioxidants. That includes the entire spectrum of dietary antioxidants, since they work best as a team. Recall that superoxide dismutase, one of the body's primary antioxidants, won't work without zinc and manganese. Other vital antioxidants include vitamin E (at least 800 units daily), vitamin C (2,000 milligrams daily) and selenium (200 micrograms daily).
Eating the recommended five daily servings of fruits and vegetables is a definite plus for anyone seeking longevity. Those foods contain compounds that aren't yet available in supplement form, including many substances that have potent antioxidant activity. They're known to help prevent many degenerative diseases, such as cardiovascular disease and cancer. One study showed that not eating the suggested five daily servings of fruits and vegetables led to a 50 percent increase in mortality.5
Since much of the damage caused by free radicals occurs in the cellular mitochondria, you might want to consider preliminary evidence that certain nutrients may shield mitochondria from oxidative damage. They include acetyl L-carnitine, alpha lipoic acid and coenzyme Q10. Increasing the level of a vital antioxidant called glutathione in the body is also known to help prevent age-related degeneration. Glutathione levels can be elevated by taking alpha lipoic acid, N-acetyl cysteine and whey protein, which has a high content of the amino acid precursor to glutathione, cysteine. As noted in a recent review in this magazine, glutamine may also offer protective effects against rampant mitochondrial internal oxidation.
References
1 Akisaka, M., et al. (1996). Energy and nutrient intakes of Okinawan centenarians. J Nutr Sci Vitaminol. 42:241-48.
2 Zachwieja, J., et al. (2001). Short-term dietary energy restriction reduces lean body mass but not performance in physically active men and women. Int J Sports Med. 22:310-16.
3 Almurshed, K., et al. (2000). The effects of dietary energy restriction on overloaded skeletal muscle in rats. British J Nutr. 84:697-704.
4 Ballor, D.E., et al. (1988). Resistance weight training during caloric restriction enhances lean body weight maintenance. Am J Clin Nutr. 47:19-25.
5 Kant, A.K., et al. (1993). Dietary diversity and subsequent mortality in the First National Health and Nutrition Examination Survey epidemiologic follow-up study. Am J Clin Nutr. 57:434. IM
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