Why Every Human Being Should Run Sprints

If you're physically able, the benefits offered by sprint intervals are truly too good to pass up.

Raise your hand if you'd like to do at least one of the following:

  • Lose weight
  • Build muscle mass
  • Increase your chance of living longer
  • Improve brain function
  • Reduce your risk of depression

If none of those sound appealing to you, congrats on your perfect life. But for the rest of us mortals, the answer is yes. We want to feel and look our best. We want to lead long, happy lives. Telling you that one simple habit can help you achieve all of these goals might sound like a sales pitch for a self-help book, but the real answer is much more simple. All you have to do is start sprinting.

While many Americans log endless hours a week plodding along on treadmills or stationary bikes at a slow-to-moderate pace, a simple sprint interval can offer bigger benefits in a much shorter time. When you look at the research, it seems like a no brainer that every able-bodied person should be performing some type of sprint on a regular basis.

I'm partial to sprints in the traditional sense, which entails running on foot as fast as possible on an open field or track. I think it beats a treadmill any day, and it also helps me get more vitamin D in my life (something the majority of Americans are sorely lacking). But sprints can also be performed via a bike, stationary bike or treadmill, if you choose. Traditional sprints may not work for everyone due to things like equipment availability, space availability, injury issues, etc. In that sense, sprints can be more loosely defined in this article as "a short burst of maximum effort running or cycling." 

So, what do sprints do that other types of cardiovascular exercise do not? A lot of the differentiating factors have to do with sprint's targeting of fast-twitch muscle fibers. Everyone has two general types of muscle—slow-twitch muscle fibers (also known as type 1 fibers) and fast-twitch muscle fibers (type 2 fibers). Although slow-twitch muscle fibers do the majority of the work during slow and moderate aerobic workouts, fast-twitch muscle fibers are used for shorter, more explosive movements—like sprinting. 

On a second-by-second basis, fast-twitch movements burn significantly more calories than slow-twitch movements. This shouldn't come as a surprise, as an activity like sprinting is much more tiresome than an activity like jogging. But the thing about sprinting is that it also helps you burn calories long after your workout has concluded via a process known as "excess post-oxygen consumption," or EPOC. During very intense exercise like sprinting, your body actually uses more oxygen than it takes in. When your workout concludes, your body has to re-oxygenate and recover from that stress. This process burns calories, largely in the form of fat. It's how four 30-second sprints can ultimately produce the same number of calories burned as 30 minutes of non-stop moderate aerobic exercise, which was exactly the case in this 2012 study.

Moreover, sprint intervals also seem to burn visceral fat—a type of fat stored in your abdomen which is particularly dangerous to accumulate—much better than moderate aerobic exercise. A study from the University of New South Wales found that a 20-minute cycling sprint interval program performed three times a week for 12 weeks led participants to burn 17 percent of their visceral fat. Researchers estimated that it would take seven hours of jogging a week for 14 straights weeks to produce a similar result, which equates to over eight times as many total minutes spent exercising. These studies are just a small part of a mountain of existing research which has found sprint intervals to be a more efficient method of burning calories and fat than moderate aerobic exercise.

But what about building muscle? Sprints are better for that, too. Slow-twitch muscle fibers do not get larger the more you exercise them. Fast-twitch muscle fibers do. So if you want to increase your muscle mass and improve your definition, you must train fast-twitch fibers via activities like sprinting. There's a reason world class marathon runners look so different from olympic sprinters.

Sprint intervals may also have a more significant impact on your mental health than traditional cardio. It's long been known that regular exercise improves brain function and combats anxiety and depression-related symptoms, but new research is finding this effect may be even greater with sprint interval training.

A 2017 animal study published in the journal Behavioural Brain Research concluded that "sprint interval training regimen, rather than intensive endurance training regimen, is highly potential to improve anxiety and depression through a greater increase in (brain-derived neurotrophic factor) contents in the brain." BDNF is essential to brain health, and low levels of BDNF have been associated with outcomes like depression, Alzheimer's, epilepsy, anxiety and impaired learning. BDNF levels naturally decline with age, but we can increase them with proper exercise and diet. There's also research that suggests sprints may help people learn faster better than just gentle running.

Although much of the earlier research in this field focused on performing four to six 30-second sprints with a few minutes of recovery in between, recent findings have found similar benefits can be achieved by performing sprints of a much shorter duration. This is great, because sprinting for 30 consecutive seconds can be quite exhausting. For example, a 2011 study published in the European Journal of Applied Physiology found that performing 10-second cycle sprints followed by four minutes of recovery produced an almost identical increase in VO2 max as performing 30-second cycle sprints followed by four minutes of recovery. Considering VO2 max is "a strong and independent predictor of all-cause and disease-specific mortality," this is an important finding. Not only that, but performing just a small number of total sprints in a training session has still been found to produce robust health benefits.

An 2017 opinion paper published in the journal Sports Medicine states, "It appears that repeating sprints is required for training to be effective. However, to date, all the available evidence suggests that [sprint interval training] protocols with fewer (two to three) and shorter (10-20 second) sprints are as good or better than the classic [sprint interval training] protocol at improving important health markers." While athletes who are required to sprint multiple times per competition need training to mimic such rigors, the average Joe simply looking to get in better shape can see results from performing a small number of short sprints during their routine. 

What does all this mean? Well, if you're serious about feeling or looking better—or both—you'd be wise to include some sort of sprint interval in your routine. Not only are they very effective for achieving a variety of common health and fitness-related goals, but they're perhaps the most efficient form of exercise out there. And notice that no where in this article did we mention you have to reach a certain speed to reap these benefits. You don't need to be Usain Bolt to sprint your way to better health—you just need to run or pedal hard. If you're concerned you may not be healthy enough for intense exercise, check with your doctor first.

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