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.

January 11, 2013

Should we eliminate the human ability to feel pain?

Though pain has clearly served an important evolutionary purpose, not everyone is convinced that we still need it. A growing number of forward-looking thinkers are suggesting that we need to get rid of it — and that we'll soon have the technological know-how to do this. But should we choose to embark on such a radical experiment, we'll need to pay close attention to the risks and those aspects of humanity we might risk losing.

Above image: "Ascension" by Hank Akins.

To help us better understand the perspective of the so-called "pain abolitionists," I spoke to philosopher and ethicist David Pearce. Back in 1995 he authored The Hedonistic Imperative, an influential online manifesto that urged the use of biotechnology to abolish suffering throughout the living world.

After speaking with Pearce, it became clear that the technologies required to pull off such a feat will soon be within our grasp — and that there's a strong moral argument to back his case. But as Pearce admitted to us, a pain-free world doesn't necessarily imply a perfect world — just one that would be considerably more comfortable to live in.

David, before we get into the ethics of creating a pain-free humanity, it's important to consider the technological viability of such a project. Will it really be possible to remove physical pain from the human experience?

In a nutshell, yes.

Technically, physical pain could be banished in humans and nonhumans alike. Today, the lives of hundreds of millions of people are blighted by chronic pain. Mercifully, most of us are normally pain-free. But at some point in our lives, pain of nightmarish intensity can strike - and then we're shocked at how dreadful the experience can be.

From an engineering perspective, however, pain is unnecessary. Nonbiological robots don't suffer its nasty "raw feels" at all. Our silicon robots can be programmed to respond adaptively to noxious stimuli without the slightest discomfort. So we know that the function of nociception and the experience of phenomenal pain are distinct.

Indeed, rare humans born with congenital analgesia never experience phenomenal pain in the course of their entire lives. The problem with congenital analgesia is that phenomenal pain normally plays a signalling role in human and nonhuman animals. So people born with congenital analgesia are at risk from all sorts of health problems. They must lead sheltered, cosseted lives. They wouldn't survive on the African savannah. Therefore the challenge we face is to find ways of replicating the functional, information-signalling role of physical pain minus its nasty raw feels.

How soon before we'll be able to start doing this?

Well, we could start right now. Pain and pain-thresholds are modulated by a number of different genes. Let's focus on just one of them here: SCN9A.

The SCN9A gene codes for the Nav1.7 sodium ion channels present at endings of pain-sensing nociceptors. The SCN9A gene has numerous variant alleles. Nonsense mutations of the SCN9A gene abolish the capacity to feel pain. Other alleles confer an unusually high pain-sensitivity or an unusually low pain-sensitivity.

So prospective parents have a choice. We can continue playing genetic roulette as now, putting our faith in God or Mother Nature. Alternatively, if we're ethically serious about reducing the burden of suffering in the world, we could use preimplantation genetic diagnosis (PGD) to choose benign "low pain" variants of the SCN9A gene for our future children. Prudence dictates that we shouldn't (yet) abolish the capacity for phenomenal pain altogether. But we can still ensure that pain has a negligible impact on our children's quality of life by selecting "low pain" alleles for their genomes.

Time out: This sounds a little bit like eugenics. Isn't all of this just genetic experimentation on our kids?

All children are genetic experiments. If we're going to create life, we should at least ensure we don't create suffering.

And you're right — critics of the reproductive revolution in process will raise the spectre of eugenics. Pessimists warn of "designer babies" and discrimination against the poor. Some of their worries may be well-founded. Potential pitfalls abound. But it's worth stressing that PGD doesn't entail creating designer babies. PGD just screens for what Nature has thrown up "naturally". True designer zygotes will certainly be an option to explore; but they aren't essential to pain-reduction.

Moreover, the biggest users of PGD aren't prospective parents in the developed western nations. Its biggest users are Indians and Chinese eager to prevent the misfortune of having a girl. Arguably our ethical priorities are skewed.

For now, adults seeking to banish pain from their lives are stuck with "analgesics" and narcotics. So-called analgesics are weak. Strong opioid painkillers have well-known problems of tolerance and dependence. Pain clinics exist "to help you manage your pain". Yet developments in gene-editing technologies will shortly allow mature humans to edit our own genetic source code. We'll be able to modulate our own pain thresholds, not just the pain-thresholds of our prospective children.

The advent of user-friendly genome-authoring and editing tools will potentially be hugely empowering. We won't all need to become molecular biologists to take control of our own genetic destiny. 

Realistically, autosomal gene-editing tools for the home user are decades away. But just as we need a Hundred Year Plan to tackle global warming, I think we need a Hundred Year Plan to tackle the scourge of physical pain.

Studies have shown that people without the capacity for pain have shorter life expectancies compared to normally functioning people. Clearly, pain has a life preserving purpose. So, without it, how will we know if we're hurt or harming ourselves? 

Just to be clear, a post-genomic world of minimal pain is not the same as a pain-free world. But if we want to phase out physical pain altogether, then its abolition needn't force us to embrace the cotton-wool existence of congenital analgesics. Instead, a regime of robust, healthy, pain-free life is technically feasible for us all.

Two long-term options for total pain-replacement deserve to be considered. One option is to replace the signalling role of pain as it exists today with information-signalling gradients of bodily well-being — with dips in bodily well-being signalling potentially noxious stimuli. Intuitively, mere dips in well-being wouldn't adequately motivate us to action. But empirically, this doesn't seem to be the case. Compare two people making love. Some aspects of lovemaking are more rewarding than others. Yet sensitive lovers can still respond and adapt to hedonic dips and peaks without ever finding their experience less than enjoyable. In principle, this lesson could be transposed to everyday life.

A more radical option for dealing with the problem of pain would be to replace the signalling role of the pleasure-pain axis in its entirety — for noxious stimuli, at any rate. This is because we could offload its current role in nociception onto smart prostheses. If equipped with smart sensors and smart prostheses, then you could painlessly and automatically withdraw your hand in the vicinity of a hot stove, say, before you inadvertently injure yourself. Or rather, your hand would withdraw automatically. Presumably, such technology would standardly be fitted with manual overrides to avoid any perceived loss of bodily autonomy.

Such enhancement technologies promise to make us "cyborgs". Not everyone finds the prospect of cyborgization appealing. Would your body software be licensed or owned? What if your body were hacked? Despite the potential snags in store, bioconservative critics might wish to reconsider their opposition to a world without pain next time they are writhing in agony. Either way, the point is that later this century the experience of phenomenal pain of any kind will become optional. Ethically speaking, we should be free to choose.

There's got to be some other trade-offs for losing the capacity for pain. Doesn't physical pain serve any other sort of purpose, such as building character or making us tougher, better — even more empathetic human beings?

Bioconservatives often quote a line from Nietzsche: "That which does not crush me makes me stronger." But alas pain often does crush people: physically, emotionally, morally. Chronic, uncontrolled pain tends to make the victim tired, depressed and weaker. True, some people are relatively resistant to physical distress. For example, high testosterone function may make someone "tougher", more "manly", more resilient, and more able to deal with physically painful stimuli. But such strength doesn't necessarily make the subject more empathetic or a better person. Indeed, if I may quote W. Somerset Maugham, "It is not true that suffering ennobles the character; happiness does that sometimes, but suffering, for the most part, makes men petty and vindictive."

Of course, suffering doesn't always enfeeble and embitter. By analogy, someone who is emotionally depressed may feel that despair is the only appropriate response to the horrors of the world. But the solution to the horrors of the world is not for us all to become depressed. Rather it's to tackle the biology of depression. Likewise, the solution to the horrors of physical pain is not to flagellate ourselves in sympathy with the afflicted. Instead it's to tackle the biological roots of suffering.

There is another possibility in terms of unanticipated side-effects: Won't we be more inclined to physically hurt or coerce people if they don't experience pain?

The infliction of physical pain is used by abusive regimes — and also by abusive parents — the world over to coerce the vulnerable. So conferring immunity to pain is more likely to promote resistance to coercion, not increased vulnerability. But phasing out the biology of physical pain is not some utopian blueprint for a perfect world, any more than the development of pain-free surgery was a panacea for the ills of the body.

Rather, the creation of a world without involuntary pain is a precondition for a civilized society.

This article originally appeared at io9.

Inset images via 1: David Pearce | 2:nobeastsofierce/shutterstock | 3:Vladimir/shutterstock.