Assume two people in their 30s who live identical lives…
The runner runs 20-30 miles a week.
The walker walks 30 miles a week at a decent clip (these miles are in addition to distance covered doing daily activities).
Assuming that all factors are equal (same weight, same diet, etc.), is the runner’s heart “healthier”? Why or why not? What makes a heart healthy? Would a cardiologist notice any differences between the hearts?
Would there be a different life expectancy between these two people?
The runner’s heart is more adapted to…running. The runner probably has a higher aerobic capacity (VO2 max). The runner may be considered more athletic, but I don’t think that necessarily makes the runner’s heart healthier. That is, the walker’s heart may function just as well for just as many years under everyday demands, and may be no more likely to develop heart disease. I would guess a cardiologist would notice a difference. I do weight training and cardio exercise and every time I get a physical my doctor or the nurse remarks on my pulse and blood pressure and asks if I exercise a lot.
Life expectancy is really just a guess on my part; that sort of thing really requires studies for a definitive answer.
Figure brisk walking pace is 3 miles an hour, so that is 10 hours of brisk walking a week. Moderate intensity.
Runs let’s make at 6 mph, so we get 5 hours of running a week. Vigorous intensity.
Basically the guideline gives vigorous a two for one factor in time, so this would be a wash by that. But the running would give the same benefit in half the time.
As was explained to me, a heart is a muscle and the exercise it gets doesn’t matter. It’s getting it up to your theoretical maximum that counts. How you achieve that, via running, swimming or walking is mute.
I imagine a runner or a swimmer(who is swimimg as in Michael Phelps and not just floats) would probably be doing aerobic exercise that will allow him to get close to and achieve his maximum benefit. Though there’s no reason a walker couldn’t do it as well
So, to be clear, the walker is doing as much work as the runner, if they travel the same distance (the runner may get a 5-10% bump in work done if they are not an efficient runner, i.e. if they bounce up and down a lot). So calories consumed is roughly the same (I know you didn’t ask that, but I’ll bet it was in the back of someone’s mind).
But aerobic benefit is very different. For the walker, they need to be walking fast enough to be breathing hard to get any aerobic benefit. Strolling or walking the dog is not, probably, going to give much aerobic benefit, nor will it do a lot to strengthen the heart muscle.
I think the chief benefit for the heart, as muscle, is that an aerobically conditioned heart beats fewer times per minute/day/year, and is more efficient. It doesn’t have to work as hard for regular daily life as a lax heart, it will generally last longer, and it will be more likely able to withstand stress.
Again, if the walker is pushing himself, going fast or up hills etc. then he may be getting good aerobic conditioning. I, for one, hate running; when I work out on a treadmill I have it ramped up to 18 or 21 degrees and do that for 30-40 minutes at a stretch, at 3 mph or better. I believe that this is giving me an aerobic benefit.
Roddy
Many runners have an “athlete’s heart.” My resting pulse rate when I was doing marathons regularly, and running over 60 miles a week, was around 40. My heart was enlarged. I went through numerous (and unnecessary) tests, including a thallium stress test and echocardiograms. The last time I had an echocardiogram (about 10 years ago), I was notified that I had to undergo another one. After the second one, I was in my treating physician’s office (not the cardiologist who did the echocardiograms), and before he came in, I took a look at my medical records hanging on the door. The cardiologist noted that my left ventricle moved very slowly but there was no shunting. He wanted another view from below. I was never told what that echocardiogram showed, but heard no further about it. My tp also told me before the echos were taken that I have partial left bundle branch block (my EKG was diagnostic of that) and would eventually need a pacemaker. I asked him if that could be an artifact of an athlete’s heart. He said No. The following year’s EKG showed no evidence of a left bundle branch block. I asked him about that, and he just shook his head.
Anyway, strenuous exercise, or at least a lot of running, does produce heart changes that light exercise (such as walking) does not. Probably for the better. An athlete’s enlarged heart is not the same as diseased cardiomegaly. The heart muscles are bigger in both, but an athlete has the blood vessels, with probably increased capillaries and arteries, and his ejection fraction is normal. At least, this is my guess. Perhaps DSeid can help with analysis in this respect.
The issue you raise in an important one in pediatrics right now because some are promoting screening all high school athletes with EKGs. Problem is that a huge number of kids are identified as having abnormalities requiring further testing and kept out based on athletic trained hearts - false positives - for a very low true positive rate: in fact it probably saves no lives at all at a cost of forcing many to go through extensive testing, exclusion from sports, and cost.
Your guess is right on the money. The ejection fraction is the same as normal. The athletic heart however fills more fully between beats (higher end diastolic volume) therefore the same ejection fraction is a fraction of a larger amount, resulting in a greater stroke volume. Hence fewer beats per minute pump the same amount of blood.
Athlete’s heart and hypertrophic cardiomyopathy (HCM) should be distinguishable by echocardiogram but doing such requires a skillful echocardiographer. In reality few are that skillful.
Ten or so years ago, when I was very sedentary (and overweight), my resting pulse was about 100. Two years ago, when I was walking regularly, and had lost some weight, my resting pulse was around 80. Now that I’m a runner (about 10-15 miles most weeks, ran a bunch of 5K and 10K races last year), my resting pulse is down to 60. I’m amazed at the change.
Thanks very much for your research and info, DSeid. Further, your first link refers to incomplete right bundle branch block in athlete’s heart is reassuring. Mine may have shown that, and not left bundle branch. My doctor said an increased interval was diagnostic of that (he could’ve said right) but I don’t recall which interval it was, but IIRC he said when it reached “19” it was diagnostic.
None of the responses answered the life expectancy question. I can’t answer that either, but I will report a conversation I had with my doctor last week. I asked how it was possible that I was still alive 47 years after a heart attack. He gave three answers. First, I gave up smoking. Second, I walk a lot (at least 20 miles a week). Third I have been taking statins since about 2000. He told me that very few of his mostly old patients (he is not taking new ones and hasn’t for at least 15 years) are dying of heart attack or strokes now. His smokers mostly died years ago and cancer is what he is losing patients to. He does not advocate running, but is a great fan of walking.
“Heart attack” is not a medical term, but colloquism for ischemic damage to the heart (myocardial infarction), and the severity of it depends on how much heart tissue was damaged. If only one coronary artery was occluded, the damage could be mild, and the heart can adapt if you take care of yourself to prevent further cardiac ischemia. IMNAMD.
The life expectancy answer is ultimately what the guideline makers were referencing when they that twice as much moderate does as much good as any particular amount of vigorous activity.