The running has become more popular, so too has running longer distances. More people than ever are participating in marathons (and even ultramarathons), leading experts to question whether more is really better.
“Stronger and faster is not always the same as healthier,” says James O’Keefe, MD, a cardiologist and associate clinical professor at the University of Missouri–Kansas City School of Medicine.
Engineering a car to win the Indy 500 is a very different goal than engineering a car to run smoothly for 500,000 miles, O’Keefe says. Likewise, designing a running plan to maximize speed and endurance is not the same goal as designing a running plan to maximize longevity. “Excessive strenuous exercise can actually erase some longevity benefits seen with moderate exercise,” he adds.
O’Keefe was once an avid runner. But he switched to other activities (including walking) after his research linked heavy running to health problems. One of O’Keefe’s studies found that while modest amounts of running are a bulwark against disease and death, too much actually erases those benefits. “Strenuous” runners — defined as people who ran faster than seven miles per hour and more than four hours per week — had similar mortality rates to sedentary adults, his study concluded.
Some researchers questioned these findings. In one response to the study, Martin Burtscher, MD, a professor at Austria’s Institute of Sports Science at the University of Innsbruck, pointed out that the study relied on self-reported pace, which could skew the findings. Burtscher says he hasn’t seen compelling evidence that people can “overdo it” with running and cites another recent study that found no drop-off in mortality benefits among people who did lots of vigorous exercise.
But the study Burtscher mentions looked at the links between “physical activity” and mortality — not at running. When you drill down into recent research on running specifically, a fair amount has found that running may increase a person’s risk for some health issues — especially heart-related ones.
The association between intense, long-term endurance exercise and atrial fibrillation—a heart irregularity that can increase a person’s risk for heart failure and stroke—is “well-accepted in the scientific community,” says Eduard Guasch, MD, a cardiac health researcher at the University of Barcelona Hospital Clinic.
While running is incredibly good for you — even in small doses — there may be some risks associated with heavy endurance training.
Guasch says it’s not yet clear how exercise may cause or contribute to the heart issue. One popular theory is that heavy amounts of endurance exercise “remodel” the heart in ways that cause dysfunction. But Guasch says this is still being debated. “There is not a clear threshold beyond which we can confidently state that a specific athlete is at an increased risk of [atrial fibrillation],” he says.
There’s also some evidence that a person’s genetic predisposition for atrial fibrillation or other heart problems could make heavy running especially risky. And for people with underlying heart conditions, marathon running is associated with a small but measurable risk of sudden cardiac death.
The takeaway (at least for now) is that while running is good for you — even in small doses — there may be some risks associated with heavy training. How much is too much? That question is hotly debated — and dependent on a person’s age, DNA, health status, and a bunch of other factors. “I think what the current available research demonstrates is that there is a range of durations and frequencies that provide longevity benefits for the average individual,” says Angelique Brellenthin, a postdoctoral researcher at Iowa State who, along with Lee, has studied the effects of running on lifespan.
Brellenthin’s research suggests a running limit of 4.5 hours a week (as often as six days per week). This dovetails with other recent research that found between 40 and 60 minutes a day of vigorous exercise is probably a safe upper limit for people who want to maximize their health.
What Should my Heart Rate Be While Running?
Finding information about heart rate training for distance runners is incredibly challenging. No doubt prior to arriving at this page you found yourself knee deep in articles about physiology that would confuse most anyone. Well we will try our hardest to straighten out confusion about using heart rate monitors while running.
When attempting to train based on heart rate, the first thing that must be discovered is your Maximum Heart Rate, because this is the base from which the rest of training is derived. There are two ways to determine max heart rate. The first is a simple calculation, [220 - Age = Max HR]. So if you are 40 years old, your max HR would be 180.
The problem with this method is that while it is quick, it is not always 100% accurate. If you are interested in finding a more accurate max HR, you can head to a nearby hill with a heart rate monitor to do a field test. Begin with a 15 minute warm up on flat ground. From there you will do 3 hill repeats. The first will be 2 minutes uphill at an effort that you could maintain for 20 minutes, then jog back down. The second repeat will be two minutes long at an effort you could maintain for 3 minutes. Note your heart rate at the top as that will be near your Max HR. Return to the bottom of the hill and let your HR drop 30-40 beats per minute. The final repeat is a 1 minute repeat all out. Note your heart rate at the end, that is your max heart rate.
Now that we know our max heart rate, we can use it while training. Greg McMillan, one of the premier distance running coaches in America, has extensively studied heart rate as it relates to training and has written about it on his website here. If you are interested in the nitty-gritty of heart rate and training, I recommend visiting his site. Be forewarned: it is complicated. I will try to simplify it as much as possible.
Basically, there are four training zones. The first is the endurance zone. This is the zone at which distance runners spend most of their time. These are the long, easy miles we do day in and day out. In this zone, our heart rate will be 60-75% of our max HR. So if our Max HR is 200, the endurance zone is 120-150. The next zone is the stamina zone. This zone is when our effort begins increasing and our breathing picks; it encompasses marathon pace all the way down to 8k pace. In this zone, our heart rate is 83%-92%. These two zones are where heart rate training is most useful. That is because in the endurance zone, we are simply attempting to build a base.
Often, runners don't spend enough time in that endurance zone. They end up running too fast, too often and get hurt. By training based on heart rate, though, we are kept in check for those many miles that are supposed to be done at a slow pace. The same can be said for the stamina zone. This zone marks the threshold between aerobic training and anaerobic training. When completing runs in this zone, the goal is to NOT go so hard as to start racing (which can often happen). By understanding our HR, we ensure that we are running exactly the right pace in both the endurance zone and stamina zone.
The final two zones, speed zones and sprint zones are not ideal for using heart rate, because they are meant to be near all-out. When attempting to work out at these zones you should not be concerned with heart rate, but rather you should be focusing on working as hard as you can.
Using heart rate monitors can be a great tool when training. They help us determine the paces we are supposed to hit on most of our runs, which can prevent us from overtraining and can keep us running healthy and strong. Use them for both motivation and to guide training, but do not be so tied to heart rate monitors that they become a source of stress. Hopefully that straightened up some heart rate confusion. Happy Running!