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There is another great reason to try to lose weight if you are overweight or obese - being overweight or obese lowers blood flow to the brain in older adults. Yikes! However, one bit of good news from a study of 495 adults (average age 69) was that increased physical activity (brisk walks count!) can reduce or eliminate this association.

This could help explain why obesity increases the risk for a number of conditions as a person gets older, such as heart disease, dementia, and Alzheimer's disease.

The study was part of the Irish Longitudinal Study on Ageing. The average BMI (body mass index) was 28, which is considered overweight. One finding was that each 1 cm increase in waist circumference was associated with the same reduction of brain (cerebral) blood flow as 1 year of advancing age. (Yes, brain volume and blood flow typically diminish with age in older adults. So you want to prevent it as much as possible.)

The study found that higher levels of physical activity can reduce or remove this association of overweight & obesity and reduced brain blood flow. So if it's not possible to lose weight - then get really physically active!

How much exercise is beneficial? The researchers recommend at least 1.5 to 2 hours per day of "being active", that is, doing activities that require "moderate" effort - this means breathing somewhat harder than normal (e.g. brisk walking, cycling at a regular pace, carrying light loads). Equally beneficial is to get some "vigorous activity" which results in breathing much higher than normal (e.g., digging, aerobics, fast cycling, carrying heavy loads). But any and all movement is good!

Medical Xpress: Researchers find obesity linked to reduced blood flow to the brain

A new study from scientists at The Irish Longitudinal Study on Aging (TILDA) at Trinity College Dublin reveals important findings, indicating that being overweight or obese significantly reduces blood flow in the brain. The study also shows that increased physical activity can positively modify, or even negate, this reduction in brain blood flow. ...continue reading "Overweight and Obesity Is Associated With Reduced Blood Flow In the Brain"

Another reason to get more active - a new study finds that being physically inactive (a couch potato) is associated with a higher risk of severe COVID-19 infection, hospitalization and ICU admission for COVID-19, and death from COVID-19. The researchers concluded that being consistently inactive should be viewed as a risk factor for severe COVID-19 outcomes, and that it is a "stronger risk factor than any of the underlying medical conditions and risk factors identified by the CDC except for age and a history of organ transplant". Yikes!

On the other hand, being physically active at least 150 minutes per week, and this includes brisk walking, is linked to lower rates of all of the above. Some activity (but under 150 minutes per week) is also better than none, but 150 minutes or more is better. The researchers state that besides vaccinations, social distancing, and mask wearing - being physically active is the single most important action individuals can take to prevent severe COVID-19 and its complications, including death.

The 150 minutes (2 1/2 hours) of physical activity per week are the recommended US Physical Activity Guidelines for adults, and include moderate and vigorous physical activity. It includes brisk walking. This can be achieved in less than 1/2 hour per day!

The researchers point out that health benefits of regular physical activity include: improved immune function, lower incidence of viral infections, as well as lower intensity and cases of death from viral infections, lowers the risk of chronic inflammation, improves cardiovascular health, increases lung capacity, muscle strength, and improves mental health. Which is why it is not surprising that persons getting a good amount of physical activity each week also generally have fewer problems with COVID-19 infections.

From CNN: Reduce risk of severe Covid with regular activity, study says. Here's how to get in 22 minutes of exercise daily

Some excerpts from the study at British Journal of Sports Medicine (BJSM): Physical inactivity is associated with a higher risk for severe COVID-19 outcomes: a study in 48,440 adult patients

Abstract: Objectives To compare hospitalisation rates, intensive care unit (ICU) admissions and mortality for patients with COVID-19 who were consistently inactive, doing some activity or consistently meeting physical activity guidelines.  ...continue reading "Reduce Your Risk of Severe COVID-19 Infection By Being Physically Active"

More evidence that there are health benefits from physical activity, even minimal amounts. Ohio State University researchers found that physical activity, even 10 minute at a time physical activity or exercise, adds up and is associated with lower amounts of cardiovascular (heart) disease in the next ten years - even for obese and overweight persons.

Being overweight or obese are risk factors for cardiovascular disease, type 2 diabetes, hypertension, and cancer. About 40% of Americans are obese and 32% are overweight, so having a way to simply and cheaply lower rates of cardiovascular disease is wonderful. Overweight is body mass index (BMI) of 25.0 to 29.9, obesity is BMI 30 or higher, and normal BMI is 18.5 to 24.8 (see CDC guidelines)

The researchers found that physical activity is more important than weight of a person in determining the risk of cardiovascular disease over the next 10 years. Unfortunately 43% of the overweight participants and 53% of the obese participants reported being sedentary (did not engage in at least 10 minutes of continuous physical activity each week) - and these groups had the highest risk of cardiovascular disease.

What counts as exercise or physical activity? Physical activity should be at least 10 continuous minutes or more, and ideally add up to 150 minutes or more each week. All moderate (e.g. brisk walking, light yard work, vacuuming, dancing) and vigorous (e.g. jogging, swimming laps, aerobics, heavy yard work) recreation activities count. The study found that engaging in less than 150 minutes a week also lowered the risk for cardiovascular disease, just not as much as for those with 150 minutes or more each week.

Government guidelines: The Physical Activity Guidelines from the US Department of Health and Human Services recommends that adults do at least 150 to 300 minutes of moderate-intensity physical activity a week, or 75 to 150 minutes of vigorous-intensity activity, or an equivalent combination of moderate- and vigorous-intensity activity.

Bottom line: Try to move, move, move as much as possible! Yes, a nice 20 minute (1 mile) walk counts!

From Medical Xpress: Not much exercise needed to lower heart disease risk for overweight people

A new study suggests, for obese or overweight adults, that any amount of exercise might lower the risk of developing cardiovascular disease in the next 10 years.  ...continue reading "Any Amount of Physical Activity Is Good For Overweight Adults"

Evidence is accumulating that engaging in exercise may not only prevent cancer, but that in those who already have cancer - it may prevent progression of the cancer. Fantastic!

A large 2019 review of 9 studies (755,459 individuals) found that 2 1/2 hours per week of "moderate-intensity" physical activity or exercise (e.g. brisk walks) really lowers the risk of 7 cancers: colon, breast, endometrial, kidney, myeloma, liver, and non-Hodgkin lymphoma. Some (but not all) were lowered in a dose response manner, that is, the more exercise (up to 5 hours per week), the bigger the protective effect.

Another 2019 review article stated that there are hundreds of studies in the field of "exercise oncology" which have examined the effect of exercise on cancer in humans. The studies find that exercise may prevent cancer, control cancer progression, and interact positively with anticancer therapies. (One example: a study found regular moderate or vigorous physical activity is associated with lower rates of death in men diagnosed with prostate cancer.)

In addition, hundreds of animal (mice and rat) and laboratory studies show that the anticancer effects of exercise are causal, not just an association. There is evidence that each exercise session actually has an effect on cancer tumors. And that the more exercise sessions, the bigger the effect!

Bottom line: Get out and move, move, move! Plan to do this every week for years.

An infographic that illustrates how exercise has anticancer effects, from The Scientist:  Infographic: Exercise’s Anticancer Mechanisms

Excerpts from the accompanying April 2020 article by Prof. Bente K. Pedersen (Univ. of Copenhagen) on how regular exercise has anticancer effects. From The Scientist: Regular Exercise Helps Patients Combat Cancer

Physical exercise is increasingly being integrated into the care of cancer patients such as Mathilde, and for good reason. Evidence is accumulating that exercise improves the well being of these patients by combating the physical and mental deterioration that often occur during anticancer treatments. Most remarkably, we are beginning to understand that exercise can directly or indirectly fight the cancer itself.  ...continue reading "Regular Exercise Has Anticancer Effects"

Exercise appears to protect against some cancers. Yes, something so simple as merely getting the recommended amount of 2 1/2 hours per week of exercise (e.g. brisk walks) really lowers the risk of 7 cancers: colon, breast, endometrial, kidney, myeloma, liver, and non-Hodgkin lymphoma.

The researchers analyzed 9 studies for a total of 755,459 individuals (median age 62 years, 53% females) who were followed for 10.1 years, and found that 50,620 cancers developed. They specifically looked at 15 cancers and found that exercise lowered the risk of 7 cancers. Some, but not all, were lowered in a dose response manner, that is, the more exercise, the bigger the protective effect (e.g. breast, colon, endometrial cancer). How much the cancer risk was lowered with exercise varied by types of cancer: colon (8%-14% lower risk in men), breast (6%-10% lower risk), endometrial (10%-18% lower risk), kidney (11%-17% lower risk), myeloma (14%-19% lower risk), liver (18%-27% lower risk), and non-Hodgkin lymphoma (11%-18% lower risk in women).

How much exercise was needed for a cancer protective effect? About 2 1/2 to 5 hours per week of moderate-intensity physical activity, such as brisk walking. The study looked at "leisure-time" exercise, which can include exercise, sports or any recreational activity which is typically "moderate to vigorous intensity".

The Physical Activity Guidelines from the US Department of Health and Human Services recommends that adults do at least 150 to 300 minutes of moderate-intensity physical activity a week, or 75 to 150 minutes of vigorous-intensity activity, or an equivalent combination of moderate- and vigorous-intensity activity. Brisk walking is moderate intensity physical activity. Bottom line: get out and move, move, move!

From Medical Xpress: Report links recommended physical activity levels to lower risk of seven cancers   ...continue reading "Exercise May Lower The Risk Of Some Cancers"

Great news for those who don't exercise at government recommended guideline levels of 150 minutes of moderate to vigorous activity per week. Which may be most of us, perhaps? Hmmm? A recent study found that even light intensity exercise is beneficial to the brain.

The study of 2354 persons (average age 53 years) in Framingham, Massachusetts, found that each additional hour spent in light-intensity physical activity was associated with a larger brain volume - equivalent to approximately 1.1 years less brain aging. Thus, the more activity, the more beneficial. In general, total cerebral brain volume declines at a rate of 0.2% per year after age 60 years - so slowing this process down is desirable.

Both physical activity levels and steps per day was looked at, and both were beneficial to brain volume. The study found that walking 10 ,000 or more steps per day was associated with higher brain volume when compared with persons who walked fewer than 5000 steps per day. But even 7500 steps was better for the brain than 5000 steps. How did they measure brain volume? With brain MRI imaging. 

This study found that light exercise is beneficial to the brain, specifically the brain volume - but note that these benefits are from levels below official recommended guidelines. The US Department of Health and Human Services (HHS) 2018 Physical Activity Guidelines for Americans state that 150 or more minutes of moderate to vigorous physical activity (MVPA) per week is recommended for substantial health benefits (but they also said that "some physical activity is better than none"). In other words, get off your butt and move - any activity and exercise is better than none!

From Science News: Light, physical activity reduces brain aging

Incremental physical activity, even at light intensity, is associated with larger brain volume and healthy brain aging ...continue reading "Light Physical Activity Is Beneficial to the Brain"

The results of a recent study suggested that walking 4 hours or more a week or 2 to 3 hours of moderate physical activity may have a (slight) protective effect of reducing stroke severity in persons who get a stroke. The study, which was conducted in Sweden, found that persons who were physically more active before their stroke and were younger in age were more likely to have a mild stroke (rather than a moderate or severe stroke). This finding was an association (didn't prove it).

But ...the majority of persons participating in the study - whether they exercised or not before the stroke - had mild strokes, and a minority in all of the groups had moderate or severe strokes. 73% of physically inactive people, 85% of those with light physical activity, and 89% of  those who had engaged in moderate physical activity before their strokes had mild strokesResearchers found that light (walking or a similar activity for at least 4 hours per week) and moderate physical activity (2 to 3 hours per week) were equally beneficial. From Medical Xpress:

People who walk just 35 minutes a day may have less severe strokes

People who participate in light to moderate physical activity, such as walking at least four hours a week or swimming two to three hours a week, may have less severe strokes than people who are physically inactive, according to a study published in the September 19, 2018, online issue of Neurology, the medical journal of the American Academy of Neurology. 

...continue reading "Could Physical Activity Reduce Stroke Severity?"

The message is clear from a recent study: older adults should get out and move, move , move (brisk walking is fine) - to lower the risk of early death. The older women engaging in the most moderate to vigorous activity had a 65% lower risk of early death during an average follow-up period of 2.3 years (when compared to the women with the least exercise).

How much exercise did the groups get? The least active had 6.8 minutes per day of moderate to vigorous exercise, and the most active had about 68 minutes/day of moderate to vigorous physical activity. The women wore a Fitbit type of device (an accelerometer) that measured their movements. Moderate to vigorous exercise was any movement that got the heart rate up a bit, made them sweat a little - and which could be brisk walking.

The study was done with older women (in their 70s), but one would think it also applies to men. Note: all-cause mortality means death from any cause (death in general). From Medscape:

Intense Exercise Tied to 65% Lower Death Risk in Older Women

Older women who engaged in the greatest amount of moderate to vigorous physical activity, such as brisk walking, were found to have a 65% lower risk of all-cause mortality compared with women who performed the least amount of such exercise, a new study reports. The researchers examined women in their early 70s in the Women's Health Study (WHS) who wore a triaxial accelerometer for 7 days to measure physical activity. The findings, by Dr I-Min Lee (Brigham and Women's Hospital, Boston, MA) and colleagues, were published November 6, 2017 in Circulation.

It's been known for a long time that physical activity is associated with lower mortality rates, Dr Lee told theheart.org | Medscape Cardiology.... Now that physical activity can be better measured using a research-grade triaxial accelerometer, the magnitude of the reduced risk of short-term death with recommended amounts of moderate to vigorous physical activity can be seen to be as strong as not smoking, Lee said. ... This study "reinforces the message that adults should strive to meet physical activity guidelines of 150 minutes of moderate or 75 minutes of vigorous exercise per week," Dr Alpa Patel (American Cancer Society, Atlanta, Georgia) who recently published a related article that showed benefits from walking told theheart.org | Medscape Cardiology.

From 2011 to 2015, 18,289 of 29,494 living women (63%) in the Women's Health Study agreed to participate in the current study.... The remaining 17,708 women were mailed a research-grade triaxial accelerometer (ActiGraph GT3X+, ActiGraph Corp) and asked to wear it on their hips for 7 days (but to take it off when sleeping or swimming) and then mail it back. 

The women spent a median of 8.4, 5.8, and 0.5 hours/day being sedentary, doing light physical activity, and doing moderate to vigorous physical activity, respectively. "The least active quartile were doing 8 minutes a day of moderate to vigorous . . . physical activity," Lee said, which was typically "brisk walking, anything that gets your heart rate up a little bit, gets you to sweat a little bit." The most active quartile did about 68 minutes/day of moderate to vigorous physical activity. During an average follow-up of 2.3 years, 207 women died. The total amount of physical activity was inversely related to the risk of all-cause mortality during follow-up, after adjustment for age and time spent wearing the device. 

Two studies (one in mice and one in humans) by 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.]

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There are health benefits to having a dog, based on results from studies and testimonials from dog owners. Now a study of millions of Swedes found  that dog ownership is associated with a lower risk of cardiovascular disease (CVD) in single-person households and a lower risk of death from cardiovascular or other causes ("all cause mortality") in general. Owning a hunting dog breed had the strongest association with cardiovascular health. Some of these health benefits are due to dogs providing companionship, affection, and increased physical activity (all those walks) of their owners. And of course there's sharing of microbes. From Science Daily:

Dog ownership linked to lower mortality rate

A team of Swedish scientists have used national registries of more than 3.4 million Swedes aged 40 to 80 to study the association between dog ownership and cardiovascular health. Their study shows that dog owners had a lower risk of death due to cardiovascular disease or to other causes during the 12-year follow-upA total of more than 3.4 million individuals without any prior cardiovascular disease in 2001 were included in the researchers' study linking together seven different national data sources, including two dog ownership registers. 

"A very interesting finding in our study was that dog ownership was especially prominent as a protective factor in persons living alone, which is a group reported previously to be at higher risk of cardiovascular disease and death than those living in a multi-person household. Perhaps a dog may stand in as an important family member in the single households. The results showed that single dog owners had a 33 percent reduction in risk of death and 11 percent reduction in risk of cardiovascular disease during follow-up compared to single non-owners. Another interesting finding was that owners to dogs from breed groups originally bred for hunting were most protected," says Mwenya Mubanga, lead junior author of the study and PhD student at the Department of Medical Sciences and the Science for Life Laboratory, Uppsala University.

"These kind of epidemiological studies look for associations in large populations but do not provide answers on whether and how dogs could protect from cardiovascular disease. We know that dog owners in general have a higher level of physical activity, which could be one explanation to the observed results. Other explanations include an increased well-being and social contacts or effects of the dog on the bacterial microbiome in the owner," says Tove Fall, senior author of the study and Associate Professor in Epidemiology at the Department of Medical Sciences and the Science for Life Laboratory, Uppsala University. "There might also be differences between owners and non-owners already before buying a dog, which could have influenced our results, such as those people choosing to get a dog tending to be more active and of better health." [Original study.]