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A recent study's results give hope to those who haven't really exercised or been physically active as they've gone through middle-age (it's viewed as "sedentary aging") and wonder if this dooms them in some way. Is it too late to get benefits from starting to exercise now? Studies show that being sedentary (that is, not being physically active or exercising weekly) and in "poor physical fitness" in middle-age is a risk factor for later heart failure. This is because a consequence of "sedentary aging" is stiffness of the heart, specifically the left ventricle (thus a loss of "cardiac plasticity").

But the study found that after 2 years of an exercise program in (formerly) sedentary middle-aged adults, they improved their maximal oxygen uptake, decreased the heart's stiffness, and improved overall fitness. All good, even though it was a small study (only 53 people completed the study). So the bottom line is: No, it's not too late to start exercising. The heart has elasticity and can remodel itself if the exercise is started before age 65 and is done 4 to 5 times a week. The adults studied were both male and female, between the ages of 45 and 64,  and exercised or were physically active for a total of 150 to 180 minutes a week, which meant at least 30 minutes 4 or 5 times a week.

Looking at the study's exercise regimen, it's clear that a variety of exercises or physical activities (low, moderate, and high intensity) is necessary. Some of the time one should be active or exercise to a point of breaking a sweat and feeling the heart pump. This meant that over time the participants increased their exercise frequency, duration, and intensity. Think about it - as you get more fit, it takes more to get your heart pumping and to break a sweat, and you can handle more exercise. 

Unfortunately the "control group", who did a combination of yoga, balance, and strength training 3 times a week for 2 years did not show improvements in heart plasticity, maximal oxygen uptake, or in overall fitness.Yikes. Sooo...the study clearly shows it is worth getting off your butt and making the effort to exercise. Perhaps view it as brushing your teeth - a daily nuisance, but necessary for health. The researchers themselves stated "Exercise is medicine." From Science Daily:

Proper exercise can reverse damage from heart aging

Exercise can reverse damage to sedentary, aging hearts and help prevent risk of future heart failure -- if it's enough exercise, and if it's begun in time, according to a new study by cardiologists at UT Southwestern and Texas Health Resources. To reap the most benefit, the exercise regimen should begin by late middle age (before age 65), when the heart apparently retains some plasticity and ability to remodel itself, according to the findings by researchers at the Institute for Exercise and Environmental Medicine (IEEM), which is a collaboration between UT Southwestern Medical Center and Texas Health Presbyterian Hospital Dallas.

And the exercise needs to be performed four to five times a week. Two to three times a week was not enough, the researchers found in an earlier study..... The regimen included exercising four to five times a week, generally in 30-minute sessions, plus warmup and cool-down: One of the weekly sessions included a high-intensity 30-minute workout, such as aerobic interval sessions in which heart rate tops 95 percent of peak rate for 4 minutes, with 3 minutes of recovery, repeated four times (a so-called "4 x 4"). Each interval session was followed by a recovery session performed at relatively low intensity. One day's session lasted an hour and was of moderate intensity. (As a "prescription for life," Levine said this longer session could be a fun activity such as tennis, aerobic dancing, walking, or biking.) One or two other sessions were performed each week at a moderate intensity, meaning the participant would break a sweat, be a little short of breath, but still be able to carry on a conversation -- the "talk test.".... One or two weekly strength training sessions using weights or exercise machines were included on a separate day, or after an endurance session.

The more than 50 participants in the study were divided into two groups, one of which received two years of supervised exercise training and the other group, a control group, which participated in yoga and balance training.A t the end of the two-year study, those who had exercised showed an 18 percent improvement in their maximum oxygen intake during exercise and a more than 25 percent improvement in compliance, or elasticity, of the left ventricular muscle of the heart, Dr. Levine noted. He compared the change in the heart to a stretchy, new rubber band versus one that has gotten stiff sitting in a drawer. Sedentary aging can lead to a stiffening of the muscle in the heart's left ventricle, the chamber that pumps oxygen-rich blood back out to the body, he explained.

"When the muscle stiffens, you get high pressure and the heart chamber doesn't fill as well with blood. In its most severe form, blood can back up into the lungs. That's when heart failure develops," said Dr. Levine, who holds the S. Finley Ewing Chair for Wellness at Texas Health Dallas and the Harry S. Moss Heart Chair for Cardiovascular Research. Earlier research by UT Southwestern cardiologists showed that left ventricular stiffening often shows up in middle age in people who don't exercise and aren't fit, leaving them with small, stiff chambers that can't pump blood as well[Original study.]

Two studies (one in mice and one in humans) from researchers at the University of Illinois found that no matter what your diet - exercise changes the gut bacteria in a beneficial way. And when you go back to a sedentary lifestyle, your gut microbes change again and beneficial microbes such as short chain fatty acids (SCFAs), especially butyrates, decline. The effect was more pronounced in lean sedentary adults (as compared to obese sedentary adults).

Beneficial microbes that increased with exercise in humans were species of Faecalibacterium, Roseburia, Lachnospira, Lachnospiraceae, and Clostridiales. Faecalibacterium prausnitzii has been discussed in earlier posts as a beneficial keystone species in the gut (here, here, and here). What kind of exercises did they do? They did three supervised 30 to 60 minute moderate to vigorous intensity aerobic/endurance exercise sessions per week for 6 weeks, and they could use a cycle ergometer (stationary bicycle) or treadmill each session.

Besides beneficial microbial changes, 6 weeks of exercising resulted in improved body composition (total lean body mass, decreased body fat, increased bone mineral density), and an improvement in cardiorespiratory fitness. These changes reversed in everyone when they went back to 6 weeks of a sedentary lifestyle. Bottom line: get out and move, move, move. Your gut microbes and your body will thank you. From Science Daily:

Exercise changes gut microbial composition independent of diet, team reports

Two studies -- one in mice and the other in human subjects -- offer the first definitive evidence that exercise alone can change the composition of microbes in the gut. The studies were designed to isolate exercise-induced changes from other factors -- such as diet or antibiotic use -- that might alter the intestinal microbiota.

In the first study, scientists transplanted fecal material from exercised and sedentary mice into the colons of sedentary germ-free mice, which had been raised in a sterile facility and had no microbiota of their own. In the second study, the team tracked changes in the composition of gut microbiota in human participants as they transitioned from a sedentary lifestyle to a more active one -- and back again.

Recipients of the exercised mouse microbiota also had a higher proportion of microbes that produce butyrate, a short-chain fatty acid that promotes healthy intestinal cells, reduces inflammation and generates energy for the host. They also appeared to be more resistant to experimental ulcerative colitis, an inflammatory bowel disease.

In the human study, the team recruited 18 lean and 14 obese sedentary adults, sampled their gut microbiomes, and started them on an exercise program during which they performed supervised cardiovascular exercise for 30-60 minutes three times a week for six weeks. The researchers sampled participants' gut microbiomes again at the end of the exercise program and after another six weeks of sedentary behavior. Participants maintained their usual diets throughout the course of the study. Fecal concentrations of SCFAs, in particular butyrate, went up in the human gut as a result of exercise. These levels declined again after the participants reverted to a sedentary lifestyle.

The most dramatic increases were seen in lean participants, who had significantly lower levels of SCFA-producing microbes in their guts to begin with. Obese participants saw only modest increases in the proportion of SCFA-producing microbes. The ratios of different microbes in the gut also differed between lean and obese participants at every stage of the study, the researchers said. "The bottom line is that there are clear differences in how the microbiome of somebody who is obese versus somebody who is lean responds to exercise," Woods said. " [Original study in humans.]

 Once again a great reason to exercise - a study found that adults with the highest levels of weekly physical activity had the longest telomeres, which are markers of overall health and aging. Think of it this way: we all age, but some people seem young for their age, while others seem old for their age. This study looked at differences among groups of people at the cellular level.

The multi-year study looked at both physical activity levels of 5,823 adults and their telomeres. The adults provided DNA samples, from which the researchers measured telomere length. Telomeres are "protein caps positioned at the end of chromosomes". Aging causes telomeres to shorten and results in gradual cell deterioration - thus they are good markers of our biological age, that is, how we're aging (rather than just our chronological age). Study author Larry A. Tucker said “We know that, in general, people with shorter telomeres die sooner and are more likely to develop many of our chronic diseases. It's not perfect, but it's a very good index of biological aging.”

What causes telomeres to shrink faster?  Telomere shortening  can be hastened by things that result in inflammation and oxidative stress, such as obesity, smoking, poor diet, type 2 diabetes, and low socioeconomic levels. On the other hand, this study found that adults with high levels of physical activity had significantly longer telomeres. The longer telomeres found in the active adults reduced cellular aging by about 9 years, as compared to those adults who were sedentary or had low to medium levels of physical activity. Nine years less of biological aging is a lot! The shortest telomeres were in sedentary people.

How much physical activity should one aim for? The study found that activity levels in the study were measured in MET-minutes (metabolic equivalent minutes) - which can sound confusing, but can be achieved by incorporating exercise into daily routines, as well as also doing vigorous activities or exercises. In the present study, men had to attain >1887 MET-minutes per week and women >1375 to be included in the category with the highest activity levels (longest telomeres). It does mean several hours a week of physical activity, which can include gardening, bicycling, walking, vacuuming, exercising, running, etc. From Science Daily:

High levels of exercise linked to nine years of less aging at the cellular level

Despite their best efforts, no scientist has ever come close to stopping humans from aging. But new research from Brigham Young University reveals you may be able to slow one type of aging -- the kind that happens inside your cells. As long as you're willing to sweat. "Just because you're 40, doesn't mean you're 40 years old biologically," Tucker said. "We all know people that seem younger than their actual age. The more physically active we are, the less biological aging takes place in our bodies."

The study, published in the medical journal Preventive Medicine, finds that people who have consistently high levels of physical activity have significantly longer telomeres than those who have sedentary lifestyles, as well as those who are moderately activeTelomeres are the protein endcaps of our chromosomes. They're like our biological clock and they're extremely correlated with age; each time a cell replicates, we lose a tiny bit of the endcaps. Therefore, the older we get, the shorter our telomeres.

Exercise science professor Larry Tucker found adults with high physical activity levels have telomeres with a biological aging advantage of nine years over those who are sedentary, and a seven-year advantage compared to those who are moderately active. To be highly active, women had to engage in 30 minutes of jogging per day (40 minutes for men), five days a week.

Tucker analyzed data from 5,823 adults who participated in the CDC's National Health and Nutrition Examination Survey, one of the few indexes that includes telomere length values for study subjects....His study found the shortest telomeres came from sedentary people -- they had 140 base pairs of DNA less at the end of their telomeres than highly active folks. Surprisingly, he also found there was no significant difference in telomere length between those with low or moderate physical activity and the sedentary people.

 A new study found differences in gut microbes between active women (they exercised at least the recommended amount) and those that are sedentary. When the gut bacteria were analyzed with modern tests (genetic sequencing) the active women had more of the health promoting beneficial bacteria such as Faecalibacterium prausnitzii, Roseburia hominis, and Akkermansia muciniphila than the sedentary women. The sedentary women also had some bacterial species not seen in the active women. The researchers said that exercise "modifies the composition of gut microbiota" (the gut microbes) in a way beneficial for health.

And what is the recommended minimal amount of exercise? The World Health Organization recommends at least 3 days of exercise per week for 30 minutes at a moderate intensity. Note that exercise can mean doing exercises, but it can also include walking briskly, intense housework (scrubbing, vacuuming with lots of bending, etc.), gardening (digging, raking, etc), or shoveling snow, etc. In this study the group of active women had at least 3 hours of physical exercise per week. Note that a sedentary lifestyle is associated with a high incidence of chronic diseases such as cardiovascular disease, cancer and diabetes, while physical exercise or activity has metabolic and immune health benefits (prevents disease).

But...reading the full study, the research also showed that the active group ate more fruits and vegetables - which we know has an effect on the gut microbiome and feeds beneficial bacteria. Although the diets of the 2 groups of women were similar in total carbohydrates, protein and fat content eaten, the active women ate more fruits, vegetables, and fiber, and the sedentary group ate more processed meat. So it looks like both exercise and a good amount of fruits and vegetables may be important for nurturing beneficial bacteria. By the way, the 3 species of beneficial bacteria mentioned currently are not found in any probiotic supplements on the market. (Earlier posts on the beneficial F. prausnitzii and Akkermansia muciniphila). From PLoS ONE:

Differences in gut microbiota profile between women with active lifestyle and sedentary women

Physical exercise is a tool to prevent and treat some of the chronic diseases affecting the world’s population. A mechanism through which exercise could exert beneficial effects in the body is by provoking alterations to the gut microbiota, an environmental factor that in recent years has been associated with numerous chronic diseases. Here we show that physical exercise performed by women to at least the degree recommended by the World Health Organization can modify the composition of gut microbiota. Using high-throughput sequencing of the 16s rRNA gene, eleven genera were found to be significantly different between active and sedentary women. Quantitative PCR analysis revealed higher abundance of health-promoting bacterial species in active women, including Faecalibacterium prausnitzii, Roseburia hominis and Akkermansia muciniphila. Moreover, body fat percentage, muscular mass and physical activity significantly correlated with several bacterial populations. In summary, we provide the first demonstration of interdependence between some bacterial genera and sedentary behavior parameters, and show that not only does the dose and type of exercise influence the composition of gut microbiota, but also the breaking of sedentary behavior.

Sedentary lifestyle is associated with a high incidence of chronic diseases such as cardiovascular disease, cancer and diabetes. Physical exercise is a powerful preventative and treatment intervention that is known to be effective in generating metabolic and immune health benefits. The gut microbiota is essential for processing dietary components and has a major role in shaping the immune system.... Dysbiosis or imbalance in gut microbiota has been associated with many diseases, among which are ulcerative colitis, Crohn's disease, colon cancer, metabolic syndrome, type I and type II diabetes, cardiovascular disease, allergy, asthma, eczema and autism.....Several studies in experimental models have addressed the relationship between gut microbiota composition and physical exercise....Collectively, these findings indicate that modulation of the microbiota by exercise depends not only on the physiological state of the individual, but also on the diet.

A total of 15 phyla were detected, in order of presence: Bacteroidetes (54%), Firmicutes (44%), Proteobacteria (0.96%), Tenericutes (0.39%), Verrucomicrobia (0.11%), Euryarchaeota (0.08%), Actinobacteria (0.07%), Lentisphaerae (0.06%), Cyanobacteria (0.050%), Spirochaetes (0.04%), Fusobacteria (0.014%), Elusimicrobia (0.009%), Synergistetes (0.007%), kTM7 (0.003%), and Acidobacteria (0.0001%). Acidobacteria (2 subjects), Elusimicrobia (2 subjects) and Spirochaetes (2 subjects) phyla were detected only in sedentary subjects.... At the genus level, there were significant differences in eleven genera: Bifidobacterium, Barnesiellaceae, Odoribacter, Paraprevotella, Turicibacter, Clostridiales, Coprococcus, Ruminococcus, and two unknown genera of Ruminococcaceae family. Given the importance of some bacterial species in health, the presence of Bifidobacterium longum, Faecalibacterium prausnitzii, Roseburia hominis, Akkermansia muciniphila was measured by qPCR. Analyses revealed a more significant abundance of F. prautznnii, R. hominis and A. muciniphila in active than in sedentary women.

Among all the genera studied, the abundance of eleven of them was significantly different between the active and sedentary group, with Paraprevotella and an unclassified genus of the Desulfovibrionaceae family specifically associated with sedentarism parameters, while the remaining genera where largely associated with diet parameters.....Nonetheless, as exercise and diet often go hand in hand, an active lifestyle is frequently associated with a high consumption of fruits and vegetables, whereas sedentarism is associated with the consumption of high-calorie and fatty foods. Indeed, exercise interventions in human populations have resulted in an improvement in diet habits. Although the diets were similar in our study regarding total carbohydrates, protein and fat content, significant differences were observed for fiber (higher in the active group) and processed meat (higher in the sedentary group).

Exercise is the Fountain of Youth? Note that they could not come up with a biomarker of aging in these active people. From Medical Xpress;

Exercise allows you to age optimally

Staying active allows you to age optimally, according to a study by King's College London and the University of Birmingham. The study of amateur older cyclists found that many had levels of physiological function that would place them at a much younger age compared to the general population; debunking the common assumption that ageing automatically makes you more frail.

The study, published in The Journal of Physiology, recruited 84 male and 41 female cycling enthusiasts aged 55 to 79 to explore how the ageing process affects the human body, and whether specific physiological markers can be used to determine your age.

Cyclists were recruited to exclude the effects of a sedentary lifestyle, which can aggravate health problems and cause changes in the body, which might appear to be due to the ageing process. Men and women had to be able to cycle 100 km in under 6.5 hours and 60 km in 5.5 hours, respectively, to be included in the study...Participants underwent two days of laboratory testing at King's. For each participant, a physiological profile was established which included measures of cardiovascular, respiratory, neuromuscular, metabolic, endocrine and cognitive functions, bone strength, and health and well-being. Volunteers' reflexes, muscle strength, oxygen uptake during exercise and peak explosive cycling power were determined.

The results of the study showed that in these individuals, the effects of ageing were far from obvious. Indeed, people of different ages could have similar levels of function such as muscle strength, lung power and exercise capacity. The maximum rate of oxygen consumption showed the closest association with age, but even this marker could not identify with any degree of accuracy the age of any given individual, which would be the requirement for any useful biomarker of ageing.

In a basic, but important test of function in older people, the time taken to stand from a chair, walk three metres, turn, walk back and sit down was also measured. Taking more than 15 seconds to complete the task generally indicates a high risk of falling. Even the oldest participants in the present study fell well below these levels, fitting well within the norm for healthy young adults.

Overall, the study concluded that ageing is likely to be a highly individualist phenomenon...The main problem facing health research is that in modern societies the majority of the population is inactive. A sedentary lifestyle causes physiological problems at any age. Hence the confusion as to how much the decline in bodily functions is due to the natural ageing process and how much is due to the combined effects of ageing and inactivity."

"In many models of ageing lifespan is the primary measure, but in human beings this is arguably less important than the consequences of deterioration in health. Healthy life expectancy - our healthspan - is not keeping pace with the average lifespan, and the years we spend with poor health and disabilities in old age are growing."

Emeritus Professor Norman Lazarus, a member of the King's team and also a cyclist, said: "Inevitably, our bodies will experience some decline with age, but staying physically active can buy you extra years of function compared to sedentary people. Cycling not only keeps you mentally alert, but requires the vigorous use of many of the body's key systems, such as your muscles, heart and lungs which you need for maintaining health and for reducing the risks associated with numerous diseases."