Living to a ripe old age is, statistically speaking, a relatively recent phenomenon. Your great-great grandfather was likely to live to the age of 46 to 51. Today, a man at 50 can expect to live until the age of 81.9, and a woman of the same age until 84.8. Many of us will live much longer than that.
This dramatic average increase in life expectancy brings us, for the first time, face to face with what it means to get old, and more specifically, what "normal" aging actually is.
We assume that aging involves a slow decline, with loss of function and increasing levels of frailty and disability. But is that "normal" aging? Many people live active, happy lives well into their 80s and 90s. Is that "abnormal" aging?
Indeed, thousands of studies now document the fact that while we can't choose our lifespan, we can have a tremendous impact on our health span. Our "health span" is a term coined to denote not how long we live, but how long we stay healthy and are able to enjoy life while we live.
The body is surprisingly malleable. What you expose we body to throughout life has a tremendous impact in the long run. And next to the foods we eat, few things have more effect on our long-term health than our level of physical activity.
How to Age 30 Years in 20 Days
In 1966, at the height of space exploration, a group of researchers decided to see what happens when the body is exposed to long periods of inactivity. They enrolled six 20-year-old male volunteers, measured their cardiovascular fitness level, and assigned them to 20 days of total bed rest, before re-measuring them on the same fitness markers.
The results would forever revolutionize how doctors think about the effects of bed rest and inactivity. In just 20 days of bed rest, the men's fitness decreased dramatically -- on markers of both muscle strength and cardiovascular fitness. It took eight weeks of intensive endurance training to get them back to previous levels.
When the researchers did a follow-up study 30 years later, they discovered something even more interesting. Now in their 50s, without engaging in any particular program of physical activity, the men were more fit at 50 than they had been after the 20 days of bed rest. In other words, three weeks of bed rest had had a more profoundly negative impact on their aerobic fitness than three decades of aging.
The result of the Dallas Bed Rest study, as it has become popularly known, should give anyone pause. It is the longest study giving us a glimpse into the dramatic effects of inactivity on the body. It shows us that the line between what we consider aging and what are really the effects of inactivity may be much more blurred than we think.
Inactivity is not an either-or; there are varying degrees. While most people are rarely confined to the complete inactivity of bed rest, we are all affected -- incrementally -- by lower levels of physical activity. Ultimately, this has significant implications for how we think about what it means to grow old, and indeed, what "normal" aging really is.
Revisiting "Normal" Aging
For an interesting perspective on "normal" aging, let's turn to another study. In 2009, a group of Japanese researchers set out to create a model for why people lose physical function as they get older. They proposed that the reasons why people lose their ability to function independently over time can be subsumed under two main models of declining function.
• The "stroke model" involves a sudden, acute onset of decline due to a sudden, life-altering event, such as a disease or injury, a stroke, an osteoporotic fracture (particularly hip fractures), spinal cord injury, and so on.
• The "disuse syndrome model" involves a gradual decline of functioning, which happens slowly (and often in steps), but without a sudden triggering event. The Japanese researchers described it as "a universal phenomenon of diminution of almost all the physiological functions of all the body systems as a consequence of inactivity. It can occur at any age, but may occur more easily and more intensively in older persons."
Here is where it gets interesting. Based on that model of declining function, the researchers surveyed a group of 542 older (65+) people assigned to long-term care assistance. Based on surveys on factors causing the loss of function, the researchers found that:
• Five in 10 elderly people with disabilities belonged to the "stroke model." No surprise there. It is well known that sudden events like a stroke or an osteoporotic fracture top the list of risk factors for disability.
• Four in 10 elderly belonged to the "disuse syndrome model." This was the big surprise. Almost as many people as those losing function because of a dramatic life event, experienced declining function for no particular reason at all -- simply from lack of activity or disuse. (Many people in this group had also mild-to-moderate chronic diseases like hypertension or diabetes, which, however, did not have a direct effect on their ability to function.)
When older persons perceive themselves as weaker, less durable, and less resilient -- and attribute it to the effect of aging -- the researchers concluded, "Quite often, in reality, it is the result of disuse syndrome as an accumulated effect of inactive life."
Does Inactivity Trigger a Syndrome of Systemic Changes?
Other researchers focusing on the parallel concept of age-related "frailty" also propose that inactivity may trigger a syndrome of "systemic" effects in the body.
Similar to the stress syndrome, which affects all bodily systems, some propose that disuse may trigger a body-wide syndrome, or a "cycle of frailty," where the combined effects of musculoskeletal, neuroendocrine, nutritional, and immunological factors conspire to set off a global deterioration of bodily functions.
In short, like a domino cascade, decreased physical activity leads to muscle weakness and bone fragility. This is in turn associated with decreased oxygen throughput, decreased arterial size, and altered blood cholesterol levels. Further down the cascade comes increasing metabolic inefficiency, obesity, and possibly Type 2 diabetes and declining immune function.
Choosing Your Health Span
If declining function isn't a normal part of aging -- but rather associated with a generalized "disuse syndrome" -- then what are the implications? Well, the implications are that we may have much greater impact on how we age than most of us realize.
Indeed, we can -- and must -- make a difference. It is easy to get trapped in a cycle of declining activity at any age. As we move less, we lose muscle mass, which makes it harder to move around, so we move even less, and in turn get less fit.
But we have a choice. There will always be wear and tear of the body, and some effects of aging and lifestyle are irreversible. But a surprising number of the changes we consider a "normal" part of aging can be slowed or completely reversed with time and patience. In the 30-year follow-up study of the five men in the Dallas Bed Rest Study, the researchers put the now 50-year-old men through a program of endurance training. In six months, they were able to completely reverse the 30-year decline in aerobic power -- although it took them six months compared to the eight weeks it took in their 20s.
In other words, we have the potential to redefine how we think about aging, and also to take greater control of the process of aging itself. So to launch you on a new start for the year, consider these five steps to make a lasting difference:
1. Find something you love. Exercising "just" to stay fit or lose weight is a losing proposition, according to Jay Kimiecik, author of The Intrinsic Exerciser. Instead, he notes, the key to sustaining the effort and motivation to be more active is to find your own enjoyable way to move. Be it dancing, walking, yoga, bicycling -- finding out which physical activities give you the most joy will help you find your inner path of exercising.
2. Put the body in charge. Most people fail at exercise programs because they put their mind in charge. Whenever we feel we "should" do more crunches or we "must" run for 30 minutes, it is the mind pushing the body to perform. If you pit mind against body, the body will always win. If you continually have to push yourself to exercise, it is only a matter of time before your body will give up.
3. Tune in. Instead, learn to listen to your body. What does it want to do? Oftentimes, you may not feel much like moving at all when you start out. Start slowly, and build from there. If you don't feel like moving much, don't force it. Start slowly without too much effort. As your body gets warmed up, you'll be surprised how you gradually feel like moving more.
4. Explore the mind-body disciplines. Holistic fitness activities that engage both mind and body -- such as yoga, tai chi, qi gong, and the martial arts -- offer a path to a deeper experience of the body. They build great sensitivity of body, mind, and senses. For many people, connecting with physical activities that offer a path of personal exploration and transformation can be a key to finding lasting joy in movement.
5. Make it a routine. If you have to find time every day for physical activity, it won't happen -- at least not as a lasting, long-term habit. Instead, schedule a time of day where you do, e.g., a morning yoga routine, or sign up to attend specific exercise classes. Take advantage of the numerous resources for online yoga, Pilates, and other great fitness activities to make physical activities an integral part of your daily or weekly routine.
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