exercise

Book Review: Haywire Heart

April 5, 2017 By Larry Creswell, MD Leave a Comment

Check out the recently published “The Haywire Heart” by Chris Case, John Mandrola, MD, and Lennard Zinn. The book is available at Amazon and other outlets.

You may recall that Case, Mandrola, and Zinn authored an article in VeloNews, entitled “Cycling to Extremes: Are endurance athletes hurting their hearts by repeatedly pushing beyond what is normal?” This was a terrific read. I wrote a previous blog post sharing my thoughts about the article and about the issue of arrhythmias and endurance sport, more generally. Their article generated much discussion in the cycling and broader endurance sports communities and the interest of readers served as the motivation for their new book.

This is a book about electrical problems in the heart–the various arrhythmias. Case, Mandrola, and Zinn are in a unique position to bring this topic to life because each has dealt personally with some form of arrhythmia. And as long time cyclists (and perhaps with some triathlon experience as well), they’re able fashion the discussion to the avid endurance athlete. From the medical perspective, the field of arrhythmias is rather complicated, both in terms of the underlying mechanisms of disease and the evaluation and treatment of affected patients, but here the authors have found a writing style that is captivating and accessible to the non-medical reader, while retaining much medical detail that will be of interest. I give them credit because this is hard to do!

I love the title. With an arrhythmia, the heart is truly “haywire.” Ignore the line on the cover, though, about “How too much exercise can kill you.” That’s unlikely to happen and there’s little in the book about that particular issue. Instead, focus on “what you can do to protect your heart.” That’s where the value lies here.

The book is organized into 9 chapters. In Chapters 1-3, the authors describe in detail how the normal heart works, outline how the heart adapts over time to endurance exercise, and introduce the medical aspects of heart attack and arrhythmias, especially for the endurance athlete. These sections are well-illustrated and are a great primer for any athlete interested in learning more about the heart.

Chapters 4-6 focus on the evidence of a link between long-time endurance exercise and arrhythmias, what to look for in yourself, and what it’s like to receive the diagnosis of an arrhythmia. Here, the authors speak from personal experience and their observations and advice are valuable.

Chapter 7 deals with the issue of exercise addiction. We know that exercise is generally healthy, but most of the benefits of exercise accrue with the first few hours per week. Why, then, do athletes exercise more? When does one become addicted? What are the implications? This is an interesting and pertinent discussion and might provoke some warranted introspection.

Chapter 8 covers the various treatment options for athletes with various arrhythmia problems. For athletes who don’t have trouble with arrhythmias, the discussion is educational in a broad sense. For those who do have arrhthymias, though, there is ample detail here to become educated and be better engaged with your doctor(s) as you sort out the best treatment for you.

Finally, in Chapter 9, the authors wrap up with their “takeaway” on how we might prevent arrhythmia problems.

One of my favorite aspects of the book is the inclusion of Case Studies sprinkled throughout the text, where the authors illustrate their points in a side bar with the personal account of an athlete. These stories bring us the human side of arrhythmias and show how difficult these problems can sometimes be.

This book is for….

the athlete with an arrhythmia problem. There’s a lot of familiar territory here as well as the opportunity to learn more. An educated patient is the ideal patient.
the athlete with simply an interest in the heart. I can’t think of a better resource to become educated about the workings of the heart, particularly as they relate to the endurance athlete.
the athlete (or the athlete’s spouse or parent) who’s afraid of causing harm to the heart through exercise. Be forewarned and be vigilant.

Related Posts:

Heart to Start, by James Beckerman, MD
The Exercise Cure, by Jordan Metzl, MD
Cardiac Athletes, by Lars Andrews

Returning to Exercise (and Training) After Heart Surgery

May 1, 2016 By Larry Creswell, MD 45 Comments

I’ve had a bunch of requests for a blog post on getting back to exercise or training after heart surgery. These requests usually come from: 1) athletes who are contemplating an upcoming operation and are already worried about if/when/whether they’ll be able to get back to exercise afterwards or 2) athletes who’ve recently had successful operations and are looking to become active once again, but are looking for reassurance that it’s safe to do so. I marvel every time I see an athlete patient get back to exercise after heart surgery, so I’m always encouraged by these inquiries.

For today’s discussion, let’s confine ourselves to what I call “conventional” heart surgery—the whole collection of heart operations that use a chest incision, with splitting of the breast bone (sternum), and make use of the heart-lung machine for cardiopulmonary bypass during the procedure. We’ll save for another day those procedures that are “less invasive” in some way, use some other incision or approach, and those that don’t make use of the heart-lung machine. As examples, I’m talking about common operations like coronary artery bypass grafting (CABG) or heart valve repair or replacement.

At the outset, we need to have a big disclaimer. Athlete patients are all different. Their operations are different, too—even when we’re talking about just the commonly performed operations. And because athletes and operations are all different, I can only generalize here.

If you’re an athlete patient, please use this post to become educated about some of the issues and help gather your thoughts for conversations with your own doctor(s). This is the only way to settle on plans that are right for you.

Athletes in this situation should remember that there are very real issues with the safety of exercise. My best advice is to take things slowly and consult with your doctor(s) frequently.

Athletes and Operations are Unique

Athletes who need heart operations can be different in many ways. Some need operation for congenital, or inherited, conditions they’ve had since birth (eg, atrial septal defect [ASD]). Others need operation for acquired conditions that take many years to develop (eg, coronary artery disease, aortic aneurysm). In still others, an emergency operation may be needed for some sort of acute problem (eg, aortic dissection).

In many cases, athletes will have conditions where the heart function is preserved, but some will have conditions where the heart has suffered some sort of damage, and become weakened, over time. Some athletes will be healthy except for their heart condition and others will have other medical conditions that affect not only the operation, but also the recovery.

Finally, athletes will come with all sorts of sports backgrounds and all sorts of future goals. Some will be young and others will be old. Some will be recreational athletes, some will be exercisers, and some will be competitive athletes. Some will have had high fitness levels before operation, and others will not. The demands of the various sports are different, too. Some have highly “dynamic” nature (eg, running). Others have a high “static” nature (eg, weightlifting).

Heart operations are different, too. In some cases, operations can be curative. In others, the operation might better be thought of as “mending a broken heart.” Moreover, in some cases the underlying heart condition can take a long time to improve, even if operation is successful.

For all of these reasons, there can be no “one-size-fits-all” prescription for return to activity, exercise, and training. Instead, the prescription must be individualized.

Healing Up

Things need to get healed up after operation. This should be obvious.

The surgical wounds need to heal after surgery. The skin incision ordinarily heals very quickly. With either skin staples or absorbable sutures beneath the skin, the surgical wound usually seals in the first few days. It’s worth paying attention to instructions for showering, bathing, and swimming. Any infection of the surgical wound can be a major setback to healing. Pay attention to instructions to watch for swelling, redness, or drainage that might be signs of infection.

Deeper, the breast bone (sternum) is like any other broken bone. We wire the sternum back together and in most cases, the bone knits back together just like any other broken bone. This is a process that takes many weeks, but we often say that the bone regains about 75% of its strength in the first month, so long as healing proceeds correctly. During the first month, we generally restrict activities that place stress on the sternum as it heals. We ask patients to avoid pushing, pulling, reaching, or even just carrying heavy objects (more than 10 pounds). Many surgeons also restrict driving for the first month. All of these activity restrictions are important because exercise early after operation must usually involve the lower body, rather than the upper body.

Deeper still, the heart itself must heal up. Regardless of the exact operation, the handiwork here usually involves needle and thread. The tissues are sewn together or new materials (eg, heart valves) are sewn into the heart. Although the tissues or devices are fixed securely in place, it takes many weeks or even months for the affected tissues to heal completely. Your surgeon will be in the best position to comment on the expected period of time that will be needed for healing and to offer advice about any longer term risks to the affected tissues, devices, or prosthetics used that might come with various forms of exercise.

One final point is that healing may be impaired in some patients. Conditions such as diabetes, a suppressed immune system (eg, from illness or medications such as steroids), or even just poor nutrition before operation can delay healing substantially.

Is the heart mended? Or good as new? Does the disease continue even after the operation?

Thinking ahead to physical activity after operation, one very important consideration is: how healthy is the heart now? Have we cured the problem? Or have we mended the problem? Or, perhaps, have we introduced some new problem?

The important question to consider is: Does my current heart situation place me at increased risk for a future problem? And, if so, how big is that risk?

As one example, sometimes an athlete will need operation to correct an atrial septal defect (ASD), an inherited condition. If this condition is found before any damage has occurred to the heart or lungs, operation is curative and athletes can generally return to any form of sports activities after they’ve healed up.

As another example, sometimes an athlete will need coronary artery bypass surgery after a heart attack, or acute myocardial infarction (MI), in medical terms. The “plumbing” can be fixed with operation so that blood flow is restored past all (or most) of the blockages in the coronary arteries. It turns out, though, that it can take up to 2 years for the ruptured plaque that caused the MI to become stabilized. During that time, the best advice might be to limit strenuous exercise because of the increased risk of repeat MI.

In yet another example, sometimes an athlete will need operation for repair of an aortic aneurysm. Most often, a portion of the enlarged aorta is “repaired” by replacing the blood vessel with a synthetic, fabric substitute. After successful operation, though, there may still be mild enlargement of the remaining aorta that deserves surveillance over time for possible enlargement. Sports activities with a high “static” component (eg, weightlifting), where there can be large increases in the blood pressure, may not be advisable, for fear of accelerating aortic enlargement over time.

These are just 3 examples. The scenarios are virtually endless.

New Medications

For some athletes, things can be so “normal” after heart surgery that no new medications are needed. Sometimes, medications that were required before the operation are no longer needed. These athletes are fortunate.

For other athletes, though, new medications can be needed either because of the underlying heart condition or because of new hardware that’s been added. As an example, aspirin, beta blockers, and statins are often recommended for athletes who’ve had operation for coronary artery disease. Each of these medications will have implications for the athlete. As another example, blood thinners like warfarin (Coumadin) might be prescribed for an athlete with a mechanical heart valve. The anticoagulants also bring a potential risk of unwanted, serious bleeding in the event of bodily injury. This is a factor which must be weighed when settling on what types of physical activity are safe.

Cardiac Rehabilitation

Cardiac rehabilitation, or “rehab” for short, is a supervised program that includes medical evaluation, development of a physical activity program specific for the patient, educational services, and individual and group exercise where the vital signs and EKG can be monitored. The structure of these programs may vary by location, but will usually involve both an inpatient phase and an outpatient phase.

At many heart surgery programs, the inpatient phase of cardiac rehab begins within the first couple days after operation, with both educational and exercise components. There are usually educational offerings about nutrition, medications, lifestyle modifications, and community resources. There is also an exercise component that is tailored to the patient, usually involving walking at first, where there is close monitoring of the vital signs, the heart rhythm, and the oxygen level in the blood stream. It’s important early after operation, together with the patient and family, to establish expectations and goals about physical activity.

Cardiac rehab continues with an outpatient phase, where patients can enroll in a monitored exercise program, often in a group setting, with several sessions per week. Athletes may sometimes fail to see the value in such a program, but these programs can actually provide some much needed structure to the early return to exercise. Most importantly, these programs can provide confidence for the athlete that once they leave a structured setting, things will still be okay with their heart and safety during exercise. I’d recommend a full cardiac rehab program for all athletes who are looking to return to exercise after operation.

For most patients, walking is the most appropriate exercise early after operation, with an emphasis on moderate exertion and increasing duration.

Support

Having a good support system is important for any patient after heart surgery. It’s particularly true for the athlete who is returning to a formal exercise or training program after heart surgery. You can envision this support system as having a set of layers.

Closest to home, athletes will benefit from a family that helps to encourage a return to physical activity and works to make this possible. Family is usually the best support for ensuring continued good nutrition, ensuring restful sleep (including naps), and seeing to other various needs after the patient returns home from the hospital.

When it comes to returning to structured, independent exercise, I believe that a group setting is often best. We all know that it’s more motivating when we have friends to meet for the morning run or ride. In the case of athletes with recent heart surgery, it’s also reassuring for the athlete to know that company is nearby if some sort of medical problem crops up during an exercise session. Even if this possibility is unlikely, a group of fellow exercisers can provide some needed confidence.

Being able to share experiences with other athletes who’ve had similar surgery can often be helpful, even if those athletes aren’t close to home. There are a variety of support groups with an online presence, but two of my favorites are the Ironheart Foundation and Cardiac Athletes. Both offer an opportunity to network with similar athletes, learn from their experiences, and also have a forum to “give back.” You’re not alone. Many other athlete patients are dealing with the same or very similar situations.

Lastly, for athletes who are looking for some good reading material, one good resource is a book entitled “Heart to Start,” by cardiologist James Beckerman, MD. I’ve written a review about this book previously here at the blog. The book describes a gradual, structured path to resuming aerobic exercise and conditioning once cardiac rehab is completed.

Follow-up

It’s wise for athlete patients to put together a robust framework of medical support as they return to physical activity after heart surgery. Your “team” should include at least your heart surgeon, your cardiologist, and your primary care provider. At the beginning, there might also be a nutritionist, your cardiac rehab specialist, or physical therapist, as well. Perhaps you can think of other important team members as well.

Continuous dialog with your team is essential. Only you will be able to describe your goals and ambitions and ask for feedback about the advisability and safety issues. Don’t assume that your doctor(s) will understand what it means to train for the masters national swimming championship or a marathon or a 70.3 triathlon. If you envision several hours of aerobic exercise as well as strength training each weak, be prepared to describe this in detail, with expected exertion levels or heart rates, so that your doctor(s) can know exactly what you have in mind. Don’t hold back.

Athletes should arrange for periodic visits with their doctor(s) so that they can discuss their plans for physical activity, share their experiences, both good and bad, develop plans, agree on any restrictions, and monitor progress. This is good advice for any athlete, but particularly good advice for athletes who have had heart surgery.

In thinking about what sorts of exercise or training is safe for their athlete patients, doctors don’t always have a bunch of accumulated scientific evidence to rely upon. I’ve written previously here at the blog about consensus recommendations about the safety of sports for young, competitive athletes with various cardiac conditions. These recommendations weren’t developed specifically for adult, recreational athletes after heart surgery, but they may provide a starting point for discussion. Often, though, doctors must rely upon judgment and personal experience with similar patients.

Warning signs of a problem

I’ve talked previously about 5 important warning signs of potential heart problems: chest pain/discomfort, unusual shortness of breath, palpitations, blacking out (or nearly so), and unusual fatigue. Athletes should be vigilant about these general warning signs and report them to their doctor(s).

There may also be additional warning signs to watch for, that are very specific to the type of surgery an athlete has had. Some examples would include:

For those with a mechanical heart valve, stroke symptoms (temporary or permanent loss of sensation or muscle weakness) would be important
For those with coronary artery disease, return of angina symptoms (chest pain/discomfort) would be important
For those with aortic aneurysms, return of chest, back, or abdominal pain would be important
For those with arrhythmias, return of an irregular heartbeat or palpitations would be important.

Sometime in the first few weeks after operation, you should have a discussion with your doctor(s) about any specific warning signs that are most important for you. And then you should be vigilant.

Summary

Let me summarize the important points:

Each athlete’s situation will be different
Whatever the approach to returning to activity, pay attention to getting healed up, as a first priority
Participate in a cardiac rehab program
Consider your “new,” current heart situation as you make plans about the safety of exercise
Rely on your support network as you return to physical activity
Assemble a medical “team” to help as you return to physical activity
Make a list and be vigilant about warning signs that are specific to your circumstance

Related Posts:

Wellness Programming: Looking for Suggestions

March 11, 2016 By Larry Creswell, MD Leave a Comment

I need your help with a project at work. Today, I’m looking for your suggestions about “wellness programming.” I’m on a mission to learn.

The university medical center where I work recently acquired a local fitness center operation here in Jackson, Mississippi. Its 4 branch facilities are being re-branded as University Wellness Centers.

Some of the readers here may know that academic medical centers are filled with committees–committees of the medical school, committees of the hospital, joint committees, ad hoc committees, etc. The list seems endless. For faculty members, there’s ordinarily a constant rotation of committee assignments.

Finally, I’ve gotten a new committee assignment that I’m looking forward to! I’m one of a group of physicians who will serve on a physician advisory board for the new Wellness Centers. We had our first meeting the other day and I’m excited about the possibilities.

One of our charges is to advise the Wellness Center management team about wellness programming. I think this is a terrific opportunity to help improve the health of our community. I’m looking for ideas that would:

Improve cardiovascular health in our community
Make use of the expertise and resources at our medical center
Provide fellowship and promote a sense of community
Be fun for the participants.

I’ll give you one example of what I’m talking about–the Heart to Start program at Providence Health & Services in Oregon. Developed by James Beckerman, M.D., and now organized at two sites in the Portland area, the program enrolls participants in a 13-week training plan to walk or run in a 5k, 10k, or half marathon event. This free program includes workout plans, heart-healthy resources, and a supportive online community. Participants can participate in person or virtually on Facebook. The photographs tell the story here–many smiling faces at the finish line.

This is just one program that has caught my attention. Perhaps you’re aware of other programs in your own community. Maybe you’ve participated. I’d love to hear about your experiences.

Please leave a comment or send me an email with your suggestions.

Related Posts:

Book Review: Heart to Start

Book Review: Heart to Start

March 13, 2015 By Larry Creswell, MD 1 Comment

Check out the newly published “Heart to Start: The Eight Week Exercise Prescription to Live Longer, Beat Heart Disease, and Run Your Best Race,” by cardiologist, James Beckerman, M.D. The book is available at Amazon and other outlets.

This is a terrific book!

First, let me share a little bit about the author. Dr. Beckerman is the Medical Director of the Center for Prevention and Wellness at the Providence Heart and Vascular Institute in Portland, Oregon. He is also the team cardiologist for the Portland Timbers Major League Soccer team and the founder and medical director for Portland’s Play Smart Youth Heart Screenings. He is passionate about wellness, exercise, and preventive cardiology. Follow him on Twitter at @jamesbeckerman.

Perhaps you’ve had a heart attack and your doctor has recommended exercise.

Perhaps you’ve discovered that your blood pressure or cholesterol is elevated and your doctor has suggested exercise as a treatment.

Perhaps you’ve just decided to get up off the couch and be more active.

The inevitable question is, “How do I get started?” This book is for you! In Dr. Beckerman’s words, “This is a book about exercise and I guarantee that it will move you….”. More coach than doctor, he will guide you every step of the way as you get going. Take him up on the offer.

This book starts with a very personal and riveting Foreword by Dave Watkins. He asks, “What is your legacy?” He shares his near-death experience with urgent heart surgery for a diseased heart valve and aortic aneurysm on the verge of rupture. There were certainly ups and downs during Dave’s recovery, but he survived and then some! Read about Dave’s return to exercise, his successes in triathlon, and the founding of his Ironheart Foundation. Dave’s story will provide ample motivation.

The book is divided into 3 sections….

Warm Up. In the first section, Dr. Beckerman helps you to take stock of your health in general and your heart in particular. He introduces the concept of preventive cardiology and illustrates this with real-world examples where “an ounce of prevention is worth a pound of cure.” Dr. Beckerman shows you how to use the Sit Rise Test and the 6-minute walk test to size up your fitness level. This section concludes with a discussion of how traditional cardiac rehab and structured exercise can be so valuable.

Workout. In the second section, Dr. Beckerman lays out what he calls your “Heart to Start Exercise Prescription.” You’ll start with an assessment of your VO2max, an index of your aerobic capacity or fitness, and then embark on an 8-week exercise program that is tailored to your fitness level. There are both HEART (aerobic exercise) and START (strength exercise) components. The program is structured but simple.

Cool Down. In the final section, Dr. Beckerman sums things up. He recognizes that there are always choices and asks you to remember to consider, “What would a healthy person do?” For those wishing to continue on, he leaves you with a 12-week exercise program that will get you to the start line of a 5K running race. It’s a program that he uses in Portland with his popular Heart to Start group (see the photo). You can be sure that the program works.

This book is for….

If you’re ready to get going, take a copy of “Heart to Start” to your next doctor’s visit and talk about getting started. Team up with your doctor to put Dr. Beckerman’s exercise prescription to work for you.

For many readers here at the blog, exercise may already be an important part of your routine. But I bet you know others, perhaps in your own family, who haven’t yet embraced exercise. Get them a copy of the book and help them get started.

Perhaps you’re in a position to organize a group exercise program like Dr. Beckerman’s Heart to Start program. I bet he’d be happy to hear from you and help you get things organized.

Related Posts (Other Book Reviews):

1. Cardiac Athletes, by Lars Andrews

2. The Exercise Cure, by Jordan Metzl, MD

Physical Activity Levels and Atrial Fibrillation

May 23, 2014 By Larry Creswell, MD 1 Comment

In the medical news last week came another interesting report on the relationship between physical activity and atrial fibrillation (AF). Reported in the medical journal, Heart, a team of investigators led by Nikola Drca from the Karolinska Institute in Stockholm gave us a study entitled “Atrial fibrillation is associated with different levels of physical activity levels at different ages in men.” This is the largest-ever study of the relationship between physical activity and AF, so the findings and conclusions deserve our attention here in the athlete community.

To set the stage for our discussion, recall that AF is a fairly common arrhythmia that is generated in the upper chambers of the heart–the left and right atrium. I’e written about AF here at the blog previously, in general terms for athletes. We’ve known for a long time that AF is associated with some other types of heart disease, particularly heart valve disease, and increases in prevalence as we age. The problem of AF is not benign. For athletes, the arrhythmia disrupts training or competition, but over the long term there is a small but real risk of stroke and also the chance of harm to the heart itself. Moreover, the available treatments–medications or ablation procedures–carry risk as well.

We also know that AF is associated with exercise. We know from prospective, longitudinal population studies that long-time, regular exercisers are more likely to develop AF over the years. And we know from targeted studies that athletes in the endurance sports are particularly at risk for developing AF.

Healthy endurance athletes should be asking the questions like:

What are my chances of developing AF?
How can I exercise safely and avoid developing AF?

Questions like these motivated the current study. Let’s take a look….

The Study

The purpose of the study was to determine if there was an association between physical activity level and the development of new AF in middle-aged men.

Back in 1997-1998, the investigators contacted all of the men aged 45-70 years who were residing in 2 counties in central Sweden and asked them to participate. About half (48,850 men, or 49%) responded by completing a questionnaire. From these, several thousand were excluded from further study because of: missing data on the questionnaire, death before the study’s follow-up period began, a current diagnosis of AF (1,496 men, or about 3% of the entire group), and the current diagnosis of some forms of cancer. This left 44,410 men to be part of the study. The average age of the participants at the time of enrollment was 60 years.

The questionnaire asked 2 questions about the amount of physical activity that the men engaged in. They were asked to think back and to recall their activity levels at age 15, at age 30, at age 50, and at the current (“baseline”) time. The participants younger than 50 years only answered for age 15 and for age 30 and “baseline.” The questions were:

“How many hours per week do you engage in leisure-time exercise (such as running, soccer, bicycling, swimming, floorball, gymnastics, cross-country skiing, etc.)?”

The respondents had to choose between:

<1 hour
1 hour
2-3 hours
4-5 hours
>5 hours.

“How much time each day do you spend walking or bicycling for everyday transportation purposes?”

The respondents had to choose between:

<20 min per day
20-40 min per day
40-60 min per day
>1 hour per day

In addition to the questions about physical activity, the respondents provided information about their medical history, smoking history, family medical history, medications, alcohol consumption, and level of education.

The respondents were then followed for 12 years to see what happened to them….and, in particular, to see if they developed AF.

The Results

At the end of the 12 years, there was an accumulated experience of 476,112 person-years! And during that time, there were 4,568 new cases of AF. Doing the math, that works out to 9.6 cases of AF per 1,000 person-years. Put another way, of the 44,410 participants, about 10.3% developed AF.

But the goal of the study was to determine if the individuals’ activity level was related to their chance of developing AF.

The primary finding of the study was that the self-reported leisure-time exercise at age 30 was indeed associated with the risk of developing AF. The investigators performed a statistical analysis designed to isolate the effect of the number of hours of exercise per week (and eliminating, as best possible, the effects of other influences on the risk of AF). They showed that the risk of developing AF was 19% greater among the individual who exercised >5 hours per week (at age 30) compared to those who exercised <1 hour per week. Remember that overall, 10.3% developed AF….so in terms of absolute risk difference between the extremes of exercise level reported at age 30, we’re talking about a couple percentage points different in the chances of developing AF. It’s because of such a large number of participants that differences this small can be detected.

Another important finding of the study was that the self-reported leisure-time exercise at baseline (when participants enrolled in the study, at mean age 60 years) was not related to the development of AF. And furthermore, the investigators found no relationship between the amount of self-reported leisure-time exercise at age 15 or at age 50 and the development of AF. The only such relationship was for the activity level at age 30.

The last important finding of the study came from a subgroup analysis. The participants who were at greatest risk of developing AF were those who reported >5 hours per week of leisure-time exercise at age 30….and <1 hour per week of leisure-time exercise at the time of enrollment in the study. These individuals were 49% more likely to develop AF during the 12-year follow-up period than individuals who exercised <1 hour per week at both age 30 and at the time of enrollment in the study.

There was no relationship between the amount of walking/cycling for transportation purposes at any age and the development of AF.

The Take-home Messages

The current study adds to our knowledge about exercise and AF. I hope that more studies are to come.
The relationship between exercise and AF is not completely understood and, indeed, the relationship may not be straightforward. Studies like this one ask participants to recall and note their activity levels at just a few moments during their lifetime. That can be hard to do, memory being what it is. Undoubtedly, the risk for developing AF must be related to some sort of dose of exercise over time. In retrospect, that’s hard to quantify. People exercise more some years than others. Some start exercising and some stop. They start and stop different types of exercise. I’ll bet that the intensity is important, too, yet how do we quantify this (in some straightforward way) so that analyses can be performed?
Previous studies, both in large longitudinal cohorts as well smaller invetigations of particular endurance athletes, have shown an increased risk of AF over the long term among individuals who exercised a lot. This phenomenon has been shown best for individuals in young to middle age, and for men more so than women. This relationship has been shown in enough different populations that we should accept it as fact. The current study points out that the increased relative risk compared to non-exercisers may reflect a rather modest increase in absolute risk. But that’s at odds with previous studies that have shown as much as a several-fold increased risk for AF among heavy exercisers. But whatever the magnitude, that risk must be considered together with the other, well-established benefits of exercise over the long term when athletes are making decisions about their activity level. Don’t forget that exercisers live longer. That’s an important endpoint to keep in mind.
The current study is curious in at least one respect. At first glance, it seems a bit odd that a relationship between exercise and development of AF could only be established for the amount of exercise reported at age 30…..and not at age 15, 50, or at the time of enrollment. Why is that? Could it be possible that we should exercise freely, with no worry about AF, while we’re young….and then again when we’re old? Maybe the 30-year-olds exercise with greater intensity. Maybe they accumulate more hours of exercise over more years. Maybe they engage in different forms of exercise that carry more risk. Perhaps “>5 hours” for the 30-year-olds was actually much more than 5 hours. The current study doesn’t provide answers. This needs to get sorted out with future studies. We need to better define the safe dose of exercise with respect to AF.
Finally, why is exercise associated with AF? In truth, we don’t know in any detail. It seems that it must have something to do with the structure of the atrium that changes over years’ time with exercise. The investigators note several of the potential reasons: enlargement of the atrium, inflammatory changes in the atrium, and overdevelopment of the parasympathetic portion of the autonomic nervous system. Perhaps all of these play a role. I like Dr. John Mandrola’s blog post this week about this issue. I like his take.

2. In the News: Atrial Fibrillation in Cross Country Skiers

3. Atrial Fibrillation in Athletes (In a Nutshell)