Death by Distance: Is Vigorous Exercise Bad for Your Heart?
- Move more, with more intensity, and sit less
- Know your target heart rate
- Start easy and work your way up
- 150 minutes of moderate, or 75 minutes vigorous, aerobic exercise / week
I blog on the fundamentals of how to start running. Running changed my life, and I want to encourage and coach others. I especially want to reach out to my peers, and coach how to start running at 40. The “one more run” philosophy is perfect for people who haven’t found a routine that works yet, because it prioritizes consistency over intensity. Most people, especially 40 and over, exercise to improve their health, and assume that all exercise works towards this goal.
How Does Intensity of Exercise Impact Our Heart Health?
But recently I listened to a podcast by Peter Attiam, featuring James O’Keefe where they suggest that intense training is actually bad for you1. I see exercise as the ultimate self-care, so the suggestion by two MDs that intense exercise is closer to self-harm was very alarming!
If you are just starting to learn how to run, I recommend starting slow, alternating between running and walking. The Running Kindness plan is made to avoid overly strenuous or intense training. As one becomes conditioned, the intensity of the training increases, but so does your body’s ability to handle it.
They compare the human body to a machine and suggest that your heart only has so many ticks before it wears out.
Is My Routine Damaging my Heart?
Now, at this point in my training, I am happy to walk when necessary, or stop and enjoy the moment, but I can handle some pretty rad runs. I love to trail run in the mountains and often gain over 1,000 feet of elevation, albeit at a slow pace.
I didn’t just step out the door one day and decide to try running up some big-ass mountains, I followed the Running Kindness program to get there, slowly working my way up from much smaller elevation gains and easier trails. And I coached myself through it all, developing a resilient mindset through the practice of self-compassion.
Anywho, my heart rate gets pretty high at times, and I’ve never considered it a danger to my health as I feel great and running and being in nature is part of my treatment for depression.
So I was very much freaked out by O’Keefe and Attiam’s podcast.
In the podcast episode they explain that exercise is the most effective “medicine” for loads of conditions. Like all medicine, they say their should be an appropriate “dose”. They compare the human body to a machine and suggest that your heart only has so many ticks before it wears out. When you train at a high heart rate, you are putting too many miles on your cardiovascular system and harming your health. They then reference a paper O’Keefe co-authored, that found statistical evidence that intense exercise is bad for you.
Why can’t a stronger, properly trained, cardiovascular machine handle more work over a lifetime?
Intense exercise is unhealthy?? Am I harming my health by taking my beloved vertical trail runs? Should I keep my heart rate below a certain level by switching to hiking up trail, and running down? Listen, I don’t have that kind of time in my day to slow down to a hike.
Scared but Skeptical
Attain and O’Keefe are medical doctors, and I am just a guy, but I question their metaphor. Sure the body’s system can be considered a complex machine, and I imagine it’s easier to do that with a doctor’s understanding of the body, but that metaphor doesn’t include the fact that we can make our body stronger through training. Why can’t a stronger, properly trained, cardiovascular machine handle more work over a lifetime? Doesn’t training lower one’s resting heart rate, because a stronger heart needs to do less work? As I understood it, a lower resting heart rate is a sign of cardiovascular strength and predictor of longevity.
Well, certainly, I don’t have the medical knowledge to answer these questions, so I dug a little deeper and checked out O’Keefe’s study, other academic work on the topic, as well as the American Heart Associations’ guidelines for exercise.
The Copenhagen City Heart Study
In O’Keefe and his colleague’s work, they looked at data from the Copenhagen City Heart study of about 7,000 people2. They studied groups of joggers and non-joggers, all without a history of coronary heart disease, and had them self-report their physical activity by duration and perceived exertion. They broke activity level into four groups,
- almost entirely sedentary, only light physical activity (biking or walking) for less than 2 hours a week,
- light physical activity for 2 to 4 hours a week,
- light physical activity for more than 4 hours a per week or more vigorous activity for 2 - 4 hours (brisk walking, fast biking, heavy gardening, sports that cause sweat and exhaustion),
- high vigorous physical activity for more than 4 hours per week or regular heavy exercise or competitive sports several times a week.
The Shocking Conclusions
Looking at the prevalence of death from any causes in each group the researchers concluded that group I and group IV have close to the same “hazard ratio” or mortality rate! Yikes!
The healthiest group was group II, light physical activity for 2 to 4 hours a week. Quite boring, IMHO.
Where Do I Fit In?
Now, I’m very interested in how this affects me, so I reviewed my activity over the past month or so.
| Activity | Quantity | Heart rate (avg) | Duration |
|---|---|---|---|
| Runs | 2 - 3 a week | 145 - 155 bpm | 1 hour |
| Dog Walks | Daily | 85 - 100 bpm | 1 hour |
| Morning Yoga | Daily | 80 bpm | 20 min |
| Just Dance 2021 (with kids) | 4 or 5 week | 130 - 145 bpm | 30 - 45 min |
| Soccer (with kids) | Weekly | 100 - 120 bpm | 1 hour |
| Family Hikes | Weekly | 95 - 100 bpm | 2 hours |
Totals
4 - 8 hours of vigorous activity
9 hours of light activity
That puts me in group IV. According to their study my heart health is equivalent to a sedentary lifestyle.
Time to Question the Study
Well that sure as hell isn’t what I want to hear, and also smells a little fishy to me. Here’s what I’m thinking:
- Group II didn’t include any vigorous activity, so that implies that any exercise beyond light biking or walking is unhealthy.
- How accurate is self reporting of vigorous versus light activity? Where are the heart rates? What someone considers light exercise: like an 8 minute mile pace, is vigorous to me. I’m not in that kind of shape!
- I’ve lived life sedentary and I can tell you I feel way better now, if that counts for something. My gut says that there is no way my heart health isn’t improved.
- Also, this would imply that a super athlete like Michael Phelps has worse cardiovascular health than I. There is no way I will outlive Michael Phelps.
I draw the line at Michael Phelps. I’m calling bullshit. I mean, I hope it’s BS, because I don’t want to scale back my activity level to group II, that would only give me 4 hours of walking the dog a week and leaving it at that. That’s not even enough activity too keep a dog healthy!
In brief the American Heart Association recommends people move more, with more intensity, and sit less.
Other Expert Opinions
Now this is just one study, and a study that came to my attention from a podcast. I shouldn't draw any conclusions yet, I need to bone up on the subject. So I checked in with American Heart Association’s guidelines for exercise, and looked into what other researchers have found on the topic.
The American Heart Association Disagrees
In brief the American Heart Association recommends people move more, with more intensity, and sit less3. Specifically:
- Get at least 150 minutes per week of moderate-intensity aerobic exercise, or 75 minutes per week of vigorous aerobic activity, or a combination of both, preferable spread throughout the week.
- Moderate to high intensity muscle strengthening activity on at least two days per week.
- Spend less time sitting.
- Gain more benefits by being active at least 5 hours per week.
- Increase amount and intensity gradually over time.
The AHA does not put a limit on how much activity one should get, and they encourage vigorous activity over moderate: contradicting the Copenhagen Study.
It also jives with the Running Kindness plan, in some ways, namely gradually increasing intensity, and running three times a week for a minimum total of 90 minutes. But the core RK plan would benefit by spreading activity throughout the week (like walking your dog every day), lowering the amount of time spent sitting, and adding strength training.
The AHA is very specific about what is moderate vs vigorous aerobic activity. Unlike the Copenhagen study, they give examples of each but also define target heart rates for each based on age4. Here is the table:
|
Age |
Target HR Zone 50-85% |
Average Maximum Heart Rate, 100% |
|---|---|---|
| 20 years | 100-170 beats per minute (bpm) | 200 bpm |
| 30 years | 95-162 bpm | 190 bpm |
| 35 years | 93-157 bpm | 185 bpm |
| 40 years | 90-153 bpm | 180 bpm |
| 45 years | 88-149 bpm | 175 bpm |
| 50 years | 85-145 bpm | 170 bpm |
| 55 years | 83-140 bpm | 165 bpm |
| 60 years | 80-136 bpm | 160 bpm |
| 65 years | 78-132 bpm | 155 bpm |
| 70 years | 75-128 bpm | 150 bpm |
To find your heart rate:
- Take your pulse on the inside of your wrist, on the thumb side.
- Use the tips of your first two fingers (not your thumb) and press lightly over the artery.
- Count your pulse for 30 seconds and multiply by 2 to find your beats per minute.
This informs the heart rate goals for those of us learning how to run. If you are just beginning, start at the lowest zone in your range (50 percent) and gradually build up.
So the American Heart Association says I am doing right by my health, I can keep up my trail running and feel confident I’m not wearing out my ticker.
Listen, almost half of my vigorous activity comes from dancing to a video game with my 8 and 10 year old, that doesn’t look like an extreme endurance athlete to me, I think I’m in the clear.
Whistle Blowers?
But sometimes, the medical community gets it wrong. Like when doctors recommended smoking or told people all fat in their diet was bad (smoking and just saturated fat is bad for you). Is this a case of the medical community screwing up, and should I heed O’Keefe’s study as a whistle blowing wake up call, and cut down on vigorous workouts? I looked through the academic literature on exercise intensity and heart health to learn more.
Theories on Why Extreme Endurance Could be Unhealthy
O’Keefe et. al. did author a paper prior to the Copenhagen study where they described the anatomical basis for potential dangers of intense exercise 5. They look at “excessive endurance exercise” (marathons, ultras, ironmans, etc.) and say emerging data shows a risk of cardiac damage. There is data that training for and competing in those events mess with your heart health, but that it returns to normal after a week. They hypothesize that months to years of repeating this type of training can create problems because one doesn’t get to recover. But they say at this point it’s hypothetical, and the topic needs more research.
Another paper states “there is almost certainly … adverse cardiac effects at the highest levels of exercise duration and intensity”6. This one goes deep into the body of academic work but can’t say at what point of intensity or duration one is “almost certainly” damaging their cardio-vascular system, they haven’t found the data yet. This might give extreme endurance athletes pause, but not me, I’m not on that level.
I checked out resting heart rate studies and found that endurance exercise (and yoga) lower your resting heart rate, which decreases risk of death from all causes.
An Even Larger Scale Study Disagrees
Another study found no evidence that high levels of cardiovascular fitness increase mortality risk and this study involved over 37,000 subjects, significantly more than the Copenhagen’s 7,0007. They contradict the Copenhagen study, finding a continuous, graded reduction in mortality as exercise capacity increases. The authors do recognize that their study involved everyday fitness and regular people, and not any extreme endurance athletes. So they can’t conclude whether that level of cardiovascular activity is damaging. Listen, almost half of my vigorous activity comes from dancing to a video game with my 8 and 10 year old, that doesn’t look like an extreme endurance athlete to me, I think I’m in the clear.
What About Resting Heart Rate?
I checked out resting heart rate studies and found that endurance exercise (and yoga) lower your resting heart rate8, which decreases risk of death from all causes9.
I also read two studies that found that, in terms of cardiovascular benefit, intensity of exercise is more important than duration. One looked at cycling10 and the other at walking11. This supports the AHA and contradicts the Copenhagen study.
Is the Copenhagen Study Straight Up Flawed?
Finally, I found a letter in the Journal of the American College of Cardiology critiquing the Copenhagen study12. The author damns the study because 1) it did not collect any data on quantity and pace, only duration and perceived intensity, 2) the conclusions are not justified by the statistical analysis. He pretty much puts the smack down on the study without mincing words.
I couldn’t find any other academic work to back up the Copenhagen study.
I'm Good
That podcast definitely had me freaked out that my beloved mountain trail running is dangerous. Then when I read the Copenhagen study, I started to really worry. Thankfully I didn’t draw any conclusions or alter my behavior based on that, I dug deeper. I believe they got it wrong on intensity, and I feel good about following the AHA recommendations and the body of research backing up their position. Their guidelines pass the smell test, our heart is a muscle, we can make it stronger and better with careful training. I learned a little bit more about target heart rates in the process.
Extreme Endurance Athletes Take Caution
I don’t know if extreme endurance exercise and training is good or bad for you. If you’re on that level, or want to reach it, you should check in with your doctor about it, of course. From what I've read, it sounds like experts want to do more research, and if one has a genetic predisposition for heart problems, extreme endurance training is dangerous.
Exercise is Still Super Good for You
I also found the AHA guidelines encouraging to the people I want my blog to reach. If you are sedentary and want to learn how to run- if you used to run and want to get back into running- if you are over 40 and want to start exercising, know that it’s not too late. The amount of exercise you need to improve your health and transform your life isn’t extreme.Nothing is as good for you as regular exercise.
Follow the Running Kindness plan. Check in with your health care professional. Commit to running 3 times a week. Walk / run and gradually increase how much you run as you get stronger. Treat yourself with kindness: coach yourself like a friend, understand fitness is universally challenging, and be mindful of self-talk.
Send me a message and tell me how I can help you train, or share your story. Thanks for reading and from the bottom of my endurance trained heart: much love to all.