A Selection of Recent Research on Exercise and Aging

A fair amount of interesting research on the topic of exercise and aging passes by every month. Most is not really worth commenting on here, other than to reinforce the point that there is a very, very large body of evidence to link regular exercise with improved long-term health and reduced mortality. Since I did note a few items worth reading recently, I thought I'd bundle them together for today's post as just such a reminder. In human studies the evidence for exercise tends to be a matter of correlation more often than causation, but the corresponding animal studies, in which researchers can put individuals into groups by level of exercise and observe the results across the life span of a cohort, leave no doubt as to the benefits provided by regular exercise. The results over the long term remain better than anything a basically healthy individual can obtain from medical science today, say to say, though that statement won't be true for many more years given the progress being made towards rejuvenation therapies. You can't exercise your way to ensuring a life span of 100 years, it isn't that large of an effect, but the benefits that can be realized are available, reliable, and free. It makes sense to take advantage of them.

The high level summary of the present research community consensus on the health benefits of exercise is that it, like many things in health and medicine, appears to have a U-shaped dose-response curve with the 80/20 point somewhere around about or a little above the standard recommendations for half an hour to an hour a day of moderate aerobic exercise. While elite athletes are shown to live a few years longer than the rest of us, it remains unclear as to whether that is due to the large amount of physical exercise or due to the fact that more robust people - who would live longer anyway - tend to have a better shot at succeeding in the world of professional athletics. At the other end of the dose-response curve, the growing use of accelerometers in studies has demonstrated that even modest levels of exercise, such as infrequent gardening or cleaning or walking, have noticeable correlations with health and mortality. More is better, however, and there is a pretty clear difference in life expectancy between those who manage regular moderate exercise and those who remain sedentary. Given that a radical change in the state of medicine lies ahead, the transition from not treating the causes of aging to actually and effectively repairing those causes, it makes sense to eke out extra years of healthy life, to increase the odds of living to take advantage of the rejuvenation biotechnologies yet to come.

Mortality and heart disease: you don't have to be an athlete to reduce the risk factors

Researchers, it is hoped, will one day find a miracle cure for all kinds of diseases. Yet over and over again it has been shown that even if it takes a little more effort than swallowing a little pill, exercise is an excellent preventive and curative treatment for many diseases. A new study shows that even low physical fitness, up to 20% below the average for healthy people, is sufficient to produce a preventive effect on most of the risk factors that affect people with cardiovascular disease. To measure the impact of physical fitness on heart disease risk factors, the researchers selected 205 men and 44 women with heart disease, including coronary artery disease, stroke, congestive heart failure, and heart valve disease, and had them undergo a stationary bike stress test to determine their fitness level. The results showed that normal physical fitness, even up to 20% below the population average, is sufficient to have a preventive effect on five of the eight risk factors affecting people with cardiovascular disease - abdominal circumference, diabetes, hypertension, obesity, and excess weight. Normal physical fitness means having the physical fitness of a person of the same weight, height, sex, and age, and who is disease-free. The easiest way to achieve this is to follow the recommendations of the World Health Organization - 150 minutes per week of moderate exercise or 75 minutes of vigorous exercise.

Does it matter how long you sit-if you are fit?

More and more studies confirm that sitting is bad for our health. It increases the likelihood of developing cardiovascular disease and other lifestyle-related illnesses such as diabetes. Some studies have estimated that being sedentary kills as many people as smoking. The average adult in the Western world sits between 9 and 11 hours a day, a number that only increases as we age. In fact, in a study in older adults just published researchers found that the least sedentary third of their study participants still spent between 12 and 13 hours in sedentary behavior, while the most sedentary of the elders in the study were sedentary for up to 15 hours a day.

But how does being fit affect the health risk associated with a sedentary lifestyle, especially in older adults, who are the most likely to be sedentary? The researchers found that older women and men in the most sedentary group were correspondingly 83% and 63% more likely to have risk factors for cardiovascular disease compared to women and men who were least sedentary. But when the researchers took fitness into account, they found that having high age-specific fitness (in this case, being among the fittest 40%) reduced the likelihood of having cardiovascular risks factors posed by extended time spent being sedentary. However, no such effect was found in those who were physically active without being fit. "Our Western lifestyles necessarily involve a lot of sitting, and we spend more and more time sitting on average as we age. But our findings show that being fit plays an important part in successful ageing and may lend protection against the negative health effects of being sedentary."

Increasing muscle strength can improve brain function

Mild Cognitive Impairment (MCI) defines people who have noticeably reduced cognitive abilities such as reduced memory but are still able to live independently, and is a precursor to Alzheimer's disease. Findings from the Study of Mental and Resistance Training (SMART) trial show, for the first time, a positive causal link between muscle adaptations to progressive resistance training and the functioning of the brain among those over 55 with MCI. "What we found in this follow up study is that the improvement in cognition function was related to their muscle strength gains. The stronger people became, the greater the benefit for their brain." SMART was a randomised, double-blind trial involving 100 community-dwelling adults with MCI, aged between 55 and 86. These new findings reinforce research from the SMART trial, whereby MRI scans showed an increase in the size of specific areas of the brain among those who took part in the weight training program. These brain changes were linked to the cognitive improvements after weight lifting.

Aerobic exercise and vascular cognitive impairment

To assess the efficacy of a progressive aerobic exercise training program on cognitive and everyday function among adults with mild subcortical ischemic vascular cognitive impairment (SIVCI), this was a proof-of-concept trial comparing a 6-month, thrice-weekly, progressive aerobic exercise training program (AT) with usual care plus education on cognitive and everyday function with a follow-up assessment 6 months after the formal cessation of aerobic exercise training. Seventy adults randomized to aerobic exercise training or usual care were included in intention-to-treat analyses. At the end of the intervention, the aerobic exercise training group had significantly improved Alzheimer's Disease Assessment Scale cognitive subscale (ADAS-Cog) performance compared with the usual care plus education group (-1.71 point difference); however, this difference was not significant at the 6-month follow-up (-0.63 point difference). There were no significant between-group differences at intervention completion and at the 6-month follow-up in EXIT-25 or ADCS-ADL performance. Examination of secondary measures showed between-group differences at intervention completion favoring the AT group in 6-minute walk distance (30.35 meter difference) and in diastolic blood pressure (-6.89 mm Hg difference). This study provides preliminary evidence for the efficacy of 6 months of thrice-weekly progressive aerobic training in community-dwelling adults with mild SIVCI, relative to usual care plus education.

Comments

@Reason: "You can't exercise your way to ensuring a life span of 100 years"

You're right. One of my heros is Jack Lalanne who exercised all his life (most of it publicly in front of the TV). I remember seeing him when I was a child in the 60s and 70s. I think he died of infection or pneumonia at age of about 93 or 94. He was promoting his juicer for some time before he died. So, yea, exercise can only push you along a little longer, but hopeful long enough to take advantage of the rejuv coming online over the next few decades.

Posted by: Robert at October 28th, 2016 9:04 PM

I remember Jack Lalanne, too. He lasted a long time, and did some amazing things all the way into his mid seventies. Swam the English Channel, things like that. He stayed pretty healthy well into old age, but you could see the cracks in his personality start to come out later in life. I'm not saying he was demented, but the age did start to show. Exercise didn't save him, but it sure did help.

So, this study about sitting has begun to irritate me. It reminds me of previous medical pronouncements, like drink 8 glasses of water a day, or no salt, or fat free diets. It's suspect. For example, the study says the average adult sits 9 to 11 hours a day, a number framed in disapproval. I recall the full study saying you increase your chance of heart disease if you sit for more than 3 hours a day. But let's do the math.

Basically, a person can only be lying down, standing (or walking) or sitting. You have to lie down for 8 hours a day, so that leaves 16 hours. If you sit for 8 hours during the day, that leaves 8 hours on your feet. Hmm. If you don't have job that requires you to stand, what would you be doing with yourself for those 8 hours of standing, really?

And how about the 3 hours a day only prescription from the study researchers? 13 hours a day on your feet?! Does anyone in the world except for salt mine slaves do that? I'm calling bullshit here...

Posted by: paul at October 29th, 2016 6:53 PM

That's a good question Paul.
I'm honestly not sure what kind of a person can manage to be standing/walking/running/etc. more than 8 hours every day. An athlete maybe?

I'd say not sitting for half of your waking day - 8 hours - would already put you in the lowest sitting percentile. Most people spend their whole day sitting.

Posted by: Anonymoose at October 29th, 2016 9:19 PM

Waitors/waitresses stand all day during their work time. They probable quickly get off their feet once the get off work, though.

But I think it makes sense that sitting too much is detrimental to our health. Before computers, TV's, and cars we were on our feet more often and more active. There were less overweight people. Now, we sit most of the time and don't get enough exercise.

Posted by: Robert at October 29th, 2016 9:38 PM

Housewives too probably stand at least 8 hours a day.

Posted by: Antonio at October 30th, 2016 2:50 AM

Arguably anyone in the trades is likely to be standing and/or walking all day, people who farm, landscapers, servers, bartenders, cooks, police that walk a beat, retail salespeople, etc, etc, etc. The more I think about it I'd say that it's mostly only office workers, scientists, students and teachers and even amongst them there are many exceptions who walk or stand all day.

Posted by: DerCribben at October 30th, 2016 6:59 AM

@DerCribben - how many people work in the trades tho? An ever smaller proportion of the population. And there's enough trades that involve sitting as well.
Farming doesn't take a lot of standing on your feet and manual labor as far as I've experienced, my grandparents used to go tend to their sizable vegetable farm after work and they worked well into their 60s, I'd go help them when I was a kid. Farming is mostly waiting for the plants to grow and providing them with water and manure or other fertilizers, besides the initial setup period there's not a whole lot of standing around in farming. Same with landscaping, it's not an everyday all day kind of job.
Retailers - it depends on the shop.
I've not seen a policeman patrol a street by foot in my parts in decades, but let's say they still do it in some countries so I'll give you that one.

Disregarding all of that, I'm not sure if it's even wise to stand and walk for more than 8 hours everyday. Most animals don't, it probably doesn't make sense for us either. And after a quick search I see that indeed, it is not.

Like everything else it's a bell-curve. If you don't stand at all you'll have problems but if you stand and walk the whole day you'll have problems as well. Finding a happy medium shouldn't be that hard. I suspect most people know by intuition when they should sit down and when they have to stretch their legs a bit - so it shouldn't be that hard to figure out.

Posted by: Anonymoose at October 30th, 2016 9:19 AM

I used to do Karate with a guy who was a hairdresser and stood all day. He was stiff as a board. Definitely a happy medium to be found here.

Posted by: Mark at October 31st, 2016 6:37 AM

I have a desk job that requires me to sit at least 8 hours a day.
Standing more takes a mentality change and some time to build the muscles and bodily support system to keep you up for long stretches.
I'm at the point now where it almost hurts and becomes uncomfortable when I sit down for more than an hour.
During the day, I typically only sit when I go to the restroom or maybe in some meeting that I couldn't get out from. Adding it all up, I sit maybe 3 to 4 hours a day spread over 15 to 30 minute chunks.
I got there by selling my car and start commuting by bike, walking or public transportation (where there's hardly ever space to sit down). You automatically build the leg and back muscle strength and flexibility that you need for standing up longer. Your whole body becomes more flexible and stronger.
Get a good desk that you can crank up to the height that is most comfortable for you and get good footwear (I prefer just wearing socks but that's most probably because I haven't spent the time yet trying to find better quality shoes).
Quite often I also find myself dancing and moving all the time while standing while working and listening to music.

Posted by: Jo at November 25th, 2016 3:38 PM

Re: all the skepticism and confusion about the hours of sedentary and active behaviors:

Sedentary Time, Cardiorespiratory Fitness, and Cardiovascular Risk Factor Clustering in Older Adults--the Generation 100 Study

To estimate ST [sedentary time] and PA [physical activity], participants wore an ActiGraph GT3X+ accelerometer (ActiGraph, LLC), which was removed only during water exposure, for 7 consecutive days. ... Epochs were set with 10-second intervals, and data between 6:00 AM and midnight were included in the analysis. The data were converted into activity counts to reflect the intensity of bodily movement. Non-wear time was excluded from the analysis. Non-wear time was defined as time periods with more than 60 consecutive minutes of zero counts, with allowance of 2 minutes of counts greater than zero. Data were included in the analysis if a participant had at least 4 days of 10 h/d or more validly recorded.

Sedentary time was estimated as all registered accelerometer data (minutes) below 100 counts/min (CPM) ... The amount of moderate to vigorous PA was estimated by summing the time spent in sustained bouts of at least 10 minutes with 1952 CPM or more, with allowance of a maximum of 2 interruptions of 2 minutes in total. Sedentary time and time spent in moderate to vigorous PA were adjusted for wear time by multiplying the recorded time by 1080 minutes (ie, a complete day of 18 hours excluding night time) and dividing it by the total wear time in minutes. Sedentary time was further converted to hours per day.

Posted by: Michael at November 26th, 2016 9:23 PM

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