January 31, 2013

Why getting physically stronger will help you live longer

Fitness trends come and go, but weight training in particular never seems to come into style. Part of the problem is that most people associate it with bodybuilding culture, and women in particular are reluctant to join the guys at the back of the gym.

But as the latest studies show, strength is a key factor in longevity and an extended healthy life. And in fact, resistance training may be the single most important thing you can add to your fitness regimen. Here's how getting stronger will make you harder to kill.

Top image: Annie Thorisdottir, winner of the 2011 and 2012 CrossFit Games, and considered the world's fittest female.

Gradual muscle decline

Simply put, we get physically weaker as we get older. Most people tend to reach the apex of their physical strength during their 20s and 30s, and it gradually declines from there. Exceptions to this rule exist, however, including genetic outliers and people who begin their resistance training later in life.

But once our strength starts to go, so too do other things. For most people, extreme declines in strength tend to happen in their 80s and 90s. Frailty as a condition results in lower levels of physical activity, decreased muscle strength, increased fatigue, slower walking speed, and unwanted weight loss. It's also associated with adverse health outcomes, an increased dependency on others, decreased mobility, disability, institutionalization — and even mortality. Weaker elderly people also tend to fall more frequently and have greater difficulty standing from sitting or lying positions.

Gerontologists place the blame on our defective mitochondria — the powerhouses of our cells. As we age, our mitochondria start to degrade, resulting in weaker cells and muscle fibres. We experience this as decreased levels of endurance, strength, and function.

Another fundamental problem of aging is our decreased production of telomerase. This is a crucial enzyme that maintains and repairs the little caps on the ends of our chromosomes. When we can't produce enough telomerase, our genetic integrity is compromised, and so too is cellular division. Chromosomal degradation is to is the human body what rust is to a car.

Our testosterone production also decreases as we get older (what is a natural anabolic steroid), resulting in a decrease in muscle and bone mass.

Muscular strength and longevity

As a consequence of all this, muscular weakness is indelibly tied to not just our quality of life, but our life expectancy as well. And the science proves this.

Two recent studies published in the British Medical Journal (here and here) revealed that muscular strength is a remarkably strong predictor of mortality — even after adjusting for cardiorespiratory fitness and other health factors.

This conclusion was reached after an analysis of over 30 studies that recorded physical attributes like bench press strength, grip strength, walking speed, chair rising speed, and standing balance. What the researchers found was that poor performance on any of the tests was associated with higher all-cause mortality — anywhere from a 1.67 to a threefold increase in the likelihood of earlier mortality (the study primarily looked at people over the age of 70 — though five looked at people under 60; but across all ages, poor physical performance was associated with increased mortality).

Now, here's the good news: To a non-trivial degree, and despite the inexorable effects of aging, physical strength is an attribute we can control. As the science is increasingly showing, resistance training can literally add years to your life — and the earlier you get to it, the better.

Resistance training and rejuvenation

Weight training (and functional exercise in general) offers innumerable positive effects on our physical, cognitive, and emotional well being. Taken as a whole, exercise has been shown to add between six and seven years to a life span — if not more.

As noted earlier, mitochondrial degradation is a primary culprit in dwindling muscle mass. But recent evidence indicates that exercise can slow down this effect. According to Mark Tarnopolsky, a professor of pediatrics and medicine at McMaster University in Hamilton, Ontario, resistance training activates a muscle stem cell called a satellite cell. In a physiological process known as ‘gene shifting,' these new cells cause the mitochondria to rejuvenate. Tarnopolsky claims that after six months of twice weekly strength exercise training, the biochemical, physiological and genetic signature of older muscles are "turned back" by a factor of 15 to 20 years. That's significant — to say the least.

Studies involving middle-aged athletes indicate that high intensity exercise protects people at the chromosomal level as well. It appears that exercise stimulates the production of telomerase, what allows for the ongoing maintenance of genetic information and cellular integrity. Exercise also triggers the production of antioxidants, which boosts the health of the body in general.

And indeed, other studies are successfully linking athleticism to longevity. A recent analysis published in Deutsches Ă„rzteblatt International of more than 900,000 athletes (ranging in age from 20 to 79) showed that no significant age-related decline in performance appeared before the age of 55. And revealingly, even beyond that age the decline was surprisingly slow; in the 65 to 69 group, a quarter of the athletes performed above average among the 20 to 54 year-old group.

Essentially, exercise helps the body regenerate itself. This likely explains why older athletes are less susceptible to age-related illnesses than their sedentary counterparts. Moreover, ongoing exercise has been shown to preserve lean tissue, even during rapid and substantial weight loss. It also helps to maintain strength and mobility, which can significantly reduce risk of injury and stave off health problems that would otherwise linger.

Even more remarkable is how resistance training can stave off cognitive decline — what is arguably just as important as physical well being. In a study led by Teresa Liu-Ambrose of the University of British Columbia, women between the ages of 70 and 80 who were experiencing mild cognitive impairment were put through 60-minute classes two times per week for 26 weeks. They used a pressurized air system (for resistance) and free weights, and were told to perform various sets of exercises with variable loads. The results were remarkable: Lifting weights improved memory and staved off the effects of dementia. It also improved the seniors' attention span and ability to resolve conflicts.

Hit the weights, everyone

Now, as these studies indicate, not all exercise is equal. Resistance training (like lifting weights), in conjunction with high intensity workouts (like aerobics and running), are key. And it's never too late to start — and yes, ladies, this means you, too ("bulking up" is a myth; moreover, it's arguably more important for women to lift weights on account of a higher propensity for osteoporosis). Most gyms offer a weightlifting area, but even workouts at home involving dumbbells, kettlebells, or even functional body weight movements will work just as effectively (things like squats, push-ups, burpees, and pull-ups).

Seniors also need to lift weights. Actually, they really need to lift weights.

Studies show that elderly people still experience the benefits of gene shifting — even if they've never lifted weights before. It also results in an increased production of growth hormone and testosterone, and lower levels of dangerous cholesterol. And as already noted, it can stave off the awful effects of neurodegenerative disorders and depression.

Unfortunately, however, many doctors and healthcare workers are hesitant to make elderly people do anything too strenuous. Today, doctors and trainers are content to advise their elderly clients to simply walk or make circles with their arms in a swimming pool. This is not enough.

Clearly, it's only common sense that seniors should exercise within their limits — but it's also fair to say that it's okay to have them engage in workouts that are more intense than what convention normally dictates.

For seniors, strength training can be something as simple as doing curls with a 2 lbs weight, or getting up and down from a chair multiple times. It's good to get the heart rate up, and it's good to be sore the next day — and in fact, those are strong indicators that the workouts are hitting the right marks.

All this said, it's important to note that any exercise of this type should be done in consultation with a doctor and under the supervision of trained professionals.

Other sources: NYT (1), NYT (2), Globe & Mail.

This article originally appeared at io9.

Inset images: Joe Belanger/Jim David/Dmitriy Shironosov/shutterstock.

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