Exercise & the heart

In the News: Aerobic Exercise Improves Memory

February 3, 2011 By Larry Creswell, MD Leave a Comment

In a recent blog entry, entitled “Exercise is Good,” I wrote about the many health benefits of exercise. As I mentioned, one area of research that has received increasing attention is the area of the cognitive benefits of exercise.

In this week’s electronic edition of the Proceedings of the National Academy of Sciences, a group of investigators led by Kirk Erickson, from the University of Pittsburgh, report on an interesting study of 120 older adults (aged 55-80) who were followed for 1 year after beginning an exercise program. Half of the group was randomized to an exercise program that was moderate-intensity aerobic exercise (40 minutes of walking) for 3 days per week. The second half of the group was randomized to an exercise program that was non-aerobic–including only stretching or toning exercises for the same amount of time.

The participants had an MRI of the brain and a test of spatial memory before and after the 1-year study period.

The investigators found that both forms of exercise program were associated with an increase in the size of the patients’ hippocampus–an area of the brain that is involved with memory. This increase was approximately 2% for the aerobic exercise group and 1.5% for the non-aerobic exercise group. We know from previous studies that this is an area of the brain that ordinarily shrinks with aging, so the new report offers encouraging news for aging adults.

The second finding from the study was that both forms of exercise program were associated with an improvement in the test of spatial memory. In this case, the aerobic exercise program did not provide any additional benefit over the non-aerobic program.

In interviews with the press, the investigators have characterized their findings as actually “turning back the clock” with the exercise program–not maintaining, but acutally improving patients’ memory. Ongoing work is now focused on determining how long these changes in hippocampal size and improved memory will last.

Exercise is Good!

January 25, 2011 By Larry Creswell, MD Leave a Comment

In my column today at EnduranceCorner, I write about the health benefits of exercise. Take a moment to visit the EnduranceCorner site for a daily article related to endurance sports. I’m reprinting the article here as well.

It’s that time of year when resolutions are on people’s minds. As we all know, one of the most common New Year’s resolutions is to exercise–often for the stated purpose of losing weight. But exercise is good for so much more. For those who want to keep score, here’s a quick tabulation of the documented health benefits of exercise.

Cardiovascular Benefits of Exercise

Lower blood pressure. There is ample evidence that physical activity is associated with lower blood pressure measurements in the general population. Moreover, exercise can be used to reduce the blood pressure (by 5-15 mm Hg) among those with high blood pressure (hypertension). In fact, an exercise program is often a component of the initial treatment of those with borderline or newly diagnosed hypertension.

Better cholesterol profile. Moderate amounts of exercise favorably affect the lipid profile by lowering the LDL (“bad”) cholesterol, total cholesterol, and triglycerides and by increasing the HDL (“good”) cholesterol. This more favorable lipid profile is associated with reduced risk of coronary artery disease (CAD).

Less chance of stroke. Although there has been conflicting evidence over the years, it is now generally accepted that moderate and high levels of exercise are associated with reduced risk of most types of stroke.

Maintaining an appropriate weight. I’m listing this benefit among the cardiovascular benefits because it is so intertwined with these benefits. Exercise is associated with less obesity and a lower prevalence of metabolic syndrome (a collection of problems such as diabetes, high blood pressure, and abnormal lipid profile).

Other Benefits of Exercise

People who exercise live longer. It doesn’t get much better than that! Given the cardiovascular benefits mentioned above, this isn’t surprising. It’s true for men and women, for smokers or nonsmokers, for the lean or overweight, and for those who are otherwise healthy or not.

In a study of middle-aged men in Sweden who were studied prospectively for a period of 20 years, investigators found that, after controlling for other relevant variables, work-related or leisure-time physical activity was associated with a protective effect on the death rate due to coronary heart disease (CHD), cancer, and, in fact, all causes.

Less chance of cancer. The National Cancer Institute reports that there is very strong evidence that physical activity is associated with reduced risk for colon and breast cancer. Although the data are not conclusive, studies have also shown that there is probably a reduced risk of endometrial (uterine), lung, and prostate cancers as well.

Increased muscle strength. Perhaps this is obvious; it takes muscles to exercise. This benefit is likely more pronounced with resistance than aerobic exercise.

Better immune system. There is accumulating evidence that moderate exercise improves the body’s immune system–its ability to fight off colds and infection. The underlying mechanisms are still being investigated. This is a double-edged sword, though. Studies have also shown that “too much” exercise may lead to the opposite effect.

Less diabetes. Adult-onset, or type 2, diabetes mellitus is associated with obesity and a sedentary lifestyle. Those who are physically active are much less likely to develop diabetes. Moreover, a moderate program of exercise is often prescribed as an effective intervention to prevent the development of diabetes among individuals who already show signs of glucose intolerance. Exercise is known to reduce blood sugar levels and to improve the body’s handling of insulin.

Better learning and memory. It has been shown that adults who exercise perform better on tests of memory, decision-making, and problem solving. The underlying mechanisms are still being studied, but exercise may increase blood flow to regions of the brain that are particularly involved in these cognitive skills. There is also preliminary evidence, at least in animal models, that physical activity may stimulate the growth of new brain neurons that may be involved in learning and memory.

Better sexual function. There is ample evidence that the incidence of erectile dysfunction is less among men who exercise. Moreover, sexual function and enjoyment are improved among individuals who avoid the problems of the metabolic syndrome, obesity, and diabetes–all of which can be mitigated by exercise.

Less osteoporosis. Especially among older women, continued exercise can help avoid the problems of osteoporosis (loss of bone density) and chronic back pain.

Better sleep. The relationship between exercise and sleep has been studied extensively. In many patient groups, those who exercise have less insomnia and better quality of sleep.

Better mental health. Lastly, there’s been increasing awareness and investigation of the mental health benefits of exercise. In a commonly mentioned study, researchers at Duke University found that among 202 individuals suffering from major depression who were treated for 16 weeks, 60% of participants who exercised for 30 minutes three times each week (and received no anti-depression medication) saw improvement in their depression symptoms–the same percentage as for those who used medication(s) alone.

I find almost universally among my athlete friends the opinion that exercise makes us “feel better.” That observation is borne out in the various scientific studies that have shown that even small amounts of exercise have been associated with incresed happiness, better energy levels and confidence, and decreased anxiety and tension.

How Much Exercise is Needed?

We’ve all heard the adage that “if some’s good, more’s better.” That’s likely true for exercise, too, at least to some reasonable extent. We’ll leave for another day the discussion about the potential adverse effects of too much exercise. But how much exercise is needed to enjoy the good benefits? I’ll bet there’s no exact amount for any single individual. If the truth were known, there are probably benefits that begin to accrue with even the first few minutes of exercise. After review of the available accumulated evidence, the American Heart Association (AHA) has formulated recommendations for both children and adults. Regarding physical activity and children, the AHA has adopted the following Scientific Position:

“Physical inactivity is a major risk factor for developing coronary artery disease. It also increases the risk of stroke and such other major cardiovascular risk factors as obesity, high blood pressure, low HDL (“good”) cholesterol and diabetes. The American Heart Association recommends that children and adolescents participate in at least 60 minutes of moderate to vigorous physical activity each day.”

Using similar reasoning, the AHA has adopted the following Scientific Position regarding physical activity in adults:

“Physical inactivity is a major risk factor for developing coronary artery disease. Coronary artery disease is characterized by deposits of fatty substances, cholesterol, calcium, and other substances in the inner lining of arteries that supply blood to the heart muscle. It also contributes to other risk factors, including obesity, high blood pressure, high triglycerides, a low level of HDL (“good”) cholesterol and diabetes. Even moderately intense physical activity such as brisk wallking is beneficial when done regularly for a total of 30 minutes or longer on most or all days.”

I suspect that most readers here have embraced exercise and made it part of their daily and weekly routine. Most of us have come to recognize a final benefit of exercise–it’s fun! This is the time of year when a few encouraging words might help a friend, family member, or co-worker stick with their New Year’s resolution to exercise. Look for that opportunity.

Happy New Year!

The Triathlete’s Heart

September 18, 2010 By Larry Creswell, MD 3 Comments

In my September column at EnduranceCorner, I shared the findings from a recent study of triathletes’ hearts. A team of radiologists in Germany used cardiac MRI to make measurements of the sizes of each of the heart’s chambers as well as the thickness of the heart muscle in a group of elite triathletes. Their findings show the adaptive changes in the heart that occur with chronic endurance training.

In the News: Some Good News for Endurance Athletes

April 13, 2010 By Larry Creswell, MD 4 Comments

In recent weeks, I’ve talked about some of the potentially adverse effects of long-term participation in endurance sports. I’ve drawn your attention to a couple recent studies that have shown that: 1) endurance athletes are more apt to develop atrial arrhythmias, sometimes long after their participation in sports has ended; and 2) marathon runners may have more plaque build-up in their coronary arteries over time than their non-runner counterparts. Each of these issues deserves further study.

On the brighter side, today’s edition of the Journal of the American College of Cardiology features a report by a group of investigators in Rome, Italy, headed by Antonio Pelliccia, MD, entitled “Long-Term Clinical Consequences of Intense, Uninterrupted Endurane Training in Olympic Athletes.” I’d like to draw your attention to both this article and an accompanying editorial by Drs. Paul Bhella and Benjamin Levine because they offer some good news about long-term heart health in endurance athletes.

The current study was motivated by several observations. As Drs. Bhella and Levine note, the primary cardiovascular adaptation in elite endurance athletes is a very large stroke volume (the amount of blood the heart ejects with each beat), “achieved by a compliant heart that relaxes quickly.” But is there any harm that comes with these adaptations? We do know that there is a consequence known as “cardiac fatigue,” a temporary reduction in heart pumping function following endurance events such as Ironman distance triathlon. We also know that there is release of cardiac enzymes (suggesting heart damage) into the bloodstream after marathon running events. What’s not known is whether there is damage to the heart over the long term.

The current study involves 114 Italian athletes from a variety of endurance disciplines (55 rowers, 19 cyclists, 8 middle-distance runners, 9 long-distance runners, 15 cross country skiers, 6 swimmers, and 2 triathletes) who participated in at least 2 consecutive Olympic games. These athletes had participated in their sports for anywhere from 1 to 15 years before selection to their first Olympic team and continued to participate in their sports for 4 to 17 years after selection to their first Olympic team. This group of athletes participated in a total of 344 Olympic games and 42 (37%) were medalists at least once.

The athletes were tested before their first Olympic games (baseline evaluation) and again (final evaluation) at their final Olympic games (or World Championships). The average time between the 2 evaluations was 8.6 +/- 3.7 years. Their cardiac evaluation at these 2 timepoints included:

1. physical examination
2. measurement of the blood pressure
3. exercise EKG
4. echocardiogram (ultrasound test of the heart).

Over the period of observation, the authors reported that there were NO cardiac events or new diagnoses of cardiomyopathy (weakening of the heart muscle). In addition, the echocardiograms showed that there were no abnormalities in the pumping function of the heart and that the dimensions of the cardiac chambers were unchanged except for a small increase in the size of the left atrium.

This news should be encouraging to the many endurance athletes out there. It’s really the first study to document preserved heart function after years of intense training and competition among endurance athletes. I suppose it’s important to recognize that the study population here is VERY select. Indeed, there are relatively few athletes who fit into the category of repeat Olympians. But the results are probably meaningful to the many millions of us who engage in some form of endurance sport. And this time, it’s good news.

In the News: Coronary Plaque Build-Up in Marathoners

April 6, 2010 By Larry Creswell, MD 8 Comments

Dr. John Mandrola, a cardiologist (specializing in electrophysiology) in Louisville, KY, who blogs at http://www.drjohnm.blogspot.com, brought an interesting report to my attention the other day.

Included among the abstracts presented at the recent annual meeting of the American College of Cardiology was a report from Dr. Jonathan Schwartz (from the University of Colorado) and his father, Dr. Robert Schwartz (from the Minneapolis Heart Institute). It turns out that father and son investigators are both runners.

These investigators examined a group of 25 runners who had completed the Twin Cities marathon for 25 consecutive years and compared these runners to a control group of non-athletes that were similar in terms of age, restinig blood pressure, renal function, smoking history, height, total and LDL cholesterol, and triglycerides. The runners did have a lower heart rate, weight, and body-mass index and higher HDL cholesterol levels.

All of the subjects underwent coronary CT angiography (CTA). This is a relatively simple x-ray test designed to find build-up of calcium in the coronary arteries (the arteries that supply the heart itself). And recall that when these arteries become blocked with calcium-laden plaque, problems such as angina or heart attack (myocardial infarction) may occur.

The investigators found that there was a significantly higher calcium plaque volume in the runners than in the control group. Sixty percent higher, in fact.

Why could this be? Again, the healthy benefits of exercise have been well-established. But the authors here suggest that these healthy benefits might be “counterbalanced by metabolic and mechanical considerations” and that the calcium plaque build-up may be “a response to high exercise levels across a lifetime.”

There have been precious few studies of the long-term effects of (potentially excessive) exercise on the cardiovascular system, so we really don’t know the cause of these findings. But it could well be the case that, beyond some point, the chronic effects of participation in endurance sports may actually be harmful.

Reports like this make you think.