The health benefits of running are clear. Not only does regular exercise help you burn calories, it can also decrease your risk of heart disease, improve the strength of your bones and joints, and even reduce your risk of developing certain kinds of cancers. Plus, running can be enjoyable. Once you get your heart rate up, feel-good chemicals like endorphins and endocannabinoids flood your system. However, at a certain point, runners may notice diminishing returns for their effort. Overtraining makes you more likely to experience injury, and it can be detrimental to your overall health. In this article, we'll discuss some of the studies that examine the optimal "dosage" for running. We'll also recommend a few ways you can avoid burnout when your training schedule exceeds the recommended dose.
What Is the Recommended Dose?
In a review of the existing literature, titled "Running as a Key Lifestyle Medicine for Longevity," researchers looked at existing data to learn more about the positive effects of running on longevity. In general, they acknowledged that runners live an average of 3 years longer than non-runners. They wanted to know whether there was an upper threshold to the beneficial effects. In their analysis, they include a table detailing the upper limit of running doses. Beyond these thresholds, they could not identify any additional benefits for longevity. The data comes from the Aerobics Center Longitudinal Study, which examined 55,137 men and women:
- Time ≤4.5 h/wk
- Distance ≤30 miles/wk
- Frequency ≤6 times/wk
In other words, if you're running more than 4.5 hours, more than 30 miles, or more than six times a week, you're unlikely to see additional benefits to your lifespan.
Supporting evidence for moderation comes from The Copenhagen City Heart Study published in the American Journal of Epidemiology. Researchers followed a random sample of 17,589 men and women over the course of 35 years, tracking their jogging habits. Jogging did have an impact on the participants’ lifespans: "The age-adjusted increase in survival with jogging was 6.2 years in men and 5.6 years in women." However, those benefits were canceled out when the number of jogging sessions exceeded three per week. The authors found no increase in survival when comparing the people who jogged more than three times per week to the non-jogging cohort.
Excessive Endurance Exercise and Cardiovascular Health
Dr. James O'Keefe of the Mid America Heart Institute and his team have published a number of studies pointing to the negative impact of excessive exercise on the heart. In one such article, titled "Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise," he outlines the process by which extreme exercise does damage.
First, a runner experiences volume overload of the atria and right ventricle, reductions in right ventricular ejection, and elevations of cardiac biomarkers. Ultimately, too much running causes plaque buildup, fibrosis, and scarring of the heart tissue. Moreover, excessive endurance exercise generates large quantities of free radicals, which may leave runners susceptible to oxidative stress and transient cardiomyocyte dysfunction. He and his fellow researchers conclude that exercise training beyond one hour a day may have diminishing returns, especially when it comes to heart health.
In heart attack survivors, exercise generally serves to decrease the risk of cardiovascular death. However, a 2014 study in Mayo Clinic Proceedings identified an upper limit to that trend. Heart attack survivors who ran more than 4.41 miles (7.1 km) per day had a higher risk of mortality than those who ran less.
Benefits to Running Everyday
In spite of the risks of excessive exercise, a daily running habit may deliver important benefits. A study in the Journal of Adolescent Health suggests that daily running promotes good mental health: "Thirty minutes of running in the morning during weekdays for 3 consecutive weeks impacted positively on sleep and psychological functioning in healthy adolescents compared with control subjects." Young runners self-reported positive impacts from running everyday.
In an interview with Runner's World, Angela Fifer, Ph.D., C.M.P.C., touts the upside of a training plan that involves daily exercise. She explains, "Some people find that it’s easier to keep up with running and other types of exercise if they make it a daily habit." For marathoners, or anyone else with a vigorous training schedule, it's important to balance the psychological benefits of a daily run with the physical benefits of a rest day.
How to Mitigate the Risks of Too Much Running
Here are a few tips to ensure that your body stays in top form.
Tip 1 - Cross Train
Alternate running days with strength-training, HIIT (high intensity interval training), swimming, and other forms of exercise. Even long-distance runners can benefit from building strength in other areas. "Cardio can’t be beat for working up a sweat and challenging your heart," Laurel Leight acknowledges in an article for Women's Health. But she adds, "...All those hours sweating with little focus on strength or flexibility can land you with overuse injuries like IT band syndrome, Achilles tendonitis, plantar fasciitis, and stress fractures." If you work out daily, try cross training as a way to avoid running too much.
Tip 2 - Wear Compression Socks
Not only are graduated compression socks good for your overall cardiovascular health, but they can also help reduce muscle soreness after a workout and clear waste fluids like myoglobin, creatine kinase, and lactic acid from your bloodstream faster. O'Keefe's study mentions that excessive exercise can increase your risk of oxidative stress, which occurs when reactive oxygen species (ROS) accumulate in the bloodstream. High levels of ROS have been associated with systemic diseases like atherogenesis, chronic venous insufficiency, and even cancer. There is some evidence to support the use of compression socks as a tool to reduce the accumulation of ROS in the lower limbs, thereby lowering the risk of major health problems, (Flore) and ample evidence shows that graduated compression improves vascular health (Lim) and functional recovery (Armstrong).
Tip 3 - Make Sure Your Shoes (and Socks) Fit Well
Injuries are common among runners. In fact, 70% of serious runners become injured during a one year period. (Lee et al.) One of the best ways to avoid shin splints, blisters, and other wear-and-tear is to run with proper form. You have a better chance of remaining healthy and strong when you wear running shoes and socks that fit. Not only will the right gear make you more comfortable, but it will also give you a more confident stride. Check out our sizing chart, which offers extra-wide calf sizes.
Tip 4 - Warm Up and Stretch
Many runners stretch before and after they run. Whether you stretch beforehand or not, try to warm up with a few minutes of light exercise, walking, or a slow pace on the elliptical before you begin running. To avoid risk of injury, it's also important to stretch after you run. We recommend leaving your compression socks on during the recovery period as you stretch your quadriceps, hamstrings, calf muscles, piriformis, gluteal muscles, and groin.
Take Days to Rest and Recover
Exercise physiologist Pamela Geisel, in an interview with Shape, explains the importance of resting: "The reason I achieved a personal best for the marathon is that twice a week (instead of just once) I took a rest day. And I mean full-blown REST day, not an active recovery day. I didn't run. I didn't swim. I didn't take a hot yoga class."
We suggest you do the same, especially if you want to live a longer, healthier life.
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