Ask a Professional: Distance Vs. Interval Running

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by Devin Sarno, NSCA-CPT
With Spring finally upon us, now is the time to start taking your workouts outdoors!  It's a great way to enjoy the weather and maybe even incorporate some outdoor running. Running is one of the most common modes of exercise; it seems pretty straight forward but in fact there is more than one way to “run”. You can run one mile straight, you can run one mile in two 800 meter segments or maybe four 400 meter segments or possibly even eight 200 meter segments! There are countless ways that you can break it up, and here's why you want to vary your runs. It may be because you cannot physically run a mile straight, or it could be to purposely change the training stimulus. But what’s the difference and why would you do one rather than the other?
First, let’s talk about steady state running, running for any given distance at the same pace without stopping. This type of run is completely aerobic and is great for helping build a strong aerobic foundation which will allow you to run longer and more efficiently, improving your cardiovascular endurance.  In a steady state run, you also work up to a moderately high heart rate in the beginning of your run but the heart rate will eventually plateau and stay steady for the remainder provided you settle into a consistent pace. During a steady state run, you will get a good calorie burn but you'll be missing out on the “afterburn” that is associated with interval training which allows you to continue burning calories even after your exercise bout. Depending on what you are training for, steady state running might be your preferred form of running. If you are preparing for a 5K, 10K, Half Marathon or something along those lines, you are definitely going to want to utilize a good amount of steady state running to build your endurance. It can also be a great tool to develop your aerobic threshold for other forms of cardiovascular exercise such as swimming or biking.
Then we have interval running. Interval running can be used by individuals new to a running program who may not have the physical capacity to run a mile or longer without stopping. If that's the case, you can split your running up with walking. This allows for you to accumulate some distance volume. By utilizing this method, you can develop your aerobic capacity at a faster rate than just running only to the point where you feel like you need to stop. To progress to a point where you could run continuously without stopping, work to lengthen your running intervals while simultaneously shortening your walking intervals.
Interval running can also be used by a wide variety of athletes. By running intervals, you can alter the training stimulus because you should be running the shorter intervals at higher intensities than your steady state run; the shorter the interval, the higher the intensity. Using our mile example, if you decide to do eight 200 meter intervals, your pace should be significantly faster on each 200 meter interval as opposed to the option of two 800 meter intervals. You must also make sure you rest and recover after each interval in order maintain a fast pace during your intervals. With faster intervals, the works becomes more anaerobic in nature, also contributing to improvements in your cardiovascular system.
Beyond helping you push your pace, making your run less aerobic and helping improve your efficiency of oxygen use, interval running also helps burn more fat throughout your run and even after. Because more fast-twitch muscle fibers will be utilized when running shorter, faster intervals, more energy will be used and in turn more calories will be burned. Both during and following your workout the higher intensity and heart rate spikes will induce a greater fat and total calorie burn so if you are running for the purpose of losing weight you may get a little more bang for your buck using the interval method.
Both forms of running absolutely have their place. Each has a different purpose, but they are both valid options. It's up to you to decide which method works best for you and what you're training for! In many cases, it's great to get a mix of both! 

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