The Balancing Act: Speed vs. Endurance

Introduce rhythm work at 5K to mile pace with short intervals such as 200-meter repeats with long rest. Photo: Scott Draper/Competitor

If you mess up the training balance, go the other way—gradually. 

While many runners can tend to overcomplicate training, when you get down to the bare bones of it all, training is essentially a balancing act. Trying to balance those two extremes of endurance and speed in the best way possible is they key to reaching our racing goals. There is a reason why we build a base before doing speed work, or include a mixture of tempo runs and 400-meter repeats during the training cycle. If we put too much undeserved emphasis on either side of the coin, performance plummets and overtraining often results. While the exact balance of speed and endurance depends on the runner and the distance they’re training for, there are scientific reasons as to why this balance is so important and some practical lessons to be learned if we mess things up.

To keep the concept simple and usable, I like to look at work that is faster than race pace and work that is slower than race pace as two opposing forces in a tug-of-war match. If we do too much work faster than race pace, then the rope gets pulled too far onto the speed side and the endurance side is going to suffer the consequences, or vice versa. So, in order to improve, we have to slowly add training stimuli to each side, or, in terms of our example, if we can keep adding equally powerful people to each side of the tug of war, the balance will remain.

In fact, we can see this balancing act in science. A recent study on high intensity interval work demonstrates this clearly. In the study they found that after performing weeks of intense interval training, the participants’ performance had improved, but it was due to what we’d call anaerobic adaptations, such as increases in an enzyme called LDH in Fast Twitch (FT) fibers. There weren’t any changes in oxidative capacity or any changes to the Slow Twitch (ST) fibers. Why? Because for this particular workout, the stimulus for adaptation was with the harder-to-recruit Fast Twitch fibers and it was in a slightly anaerobic way. If we did this workout continuously without any endurance side support, we’d get a further and further shift until, eventually, our FT fibers would be really trained, but our ST fibers would be neglected. If we looked at studies on longer aerobic work, we’d see the exact opposite effect.

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The key then is keeping balance between these opposing forces, and supporting the anaerobic work with aerobic work and vice versa. That’s why blending training throughout the season is important and doing large blocks of one kind of training doesn’t work for very long. In the practical sense, this means during the base phase you shouldn’t just slog out the miles. Add in some hill sprints or some easy 200s at 5K down to mile race pace. It also means that you shouldn’t neglect the long run, aerobic intervals or tempo runs during the competition phase. You don’t have to do as many as when trying to build the component, but enough needs to be done to balance out the faster work that is being emphasized.

Straightening Out The Balance

So what happens if we do mess up the training balance? The first step is identifying the issue.  More often than not, during the competition season it is either neglecting the aerobic side of things or overemphasizing the anaerobic side. During the base phase, it’s usually a neglecting of the speed side.

If the issue is a deteriorating aerobic system, then the first step is to gradually introduce more aerobic work.  This can be done via two methods: First, if you catch the speed side emphasis early, all it takes is an easy aerobic workout or two to get you back on track. One of my favorites is a simple aerobic fartlek which consists of the following segments: 10 minutes, 7 minutes, 5 minutes, 3 minutes, all separated by a 3- to 4-minute jog. Begin the first segment at marathon race pace and gradually work down to just faster than 10K pace. It shouldn’t be too tough of a workout, but instead is used to go through the array of aerobic paces to jump start your aerobic system. In situations where the balance is really messed up, do what I call an “aerobic refresh”, which consists of 7- to 14 days of nothing but easy mileage, long runs, and tempo runs that are only moderate in terms of difficulty. Think of it as going back to base building for a week or two.

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On the flipside of things, but one that is easier to overcome, is overemphasis on endurance work. The solution to this problem is relatively easy. Insert some moderate faster-paced work depending on the runner and the distance they’re training for. I like to attack the problem from two angles: First, introduce pure speed work in the form of 60 to 80-meter gradual uphill sprints to prime the neuromuscular system. Then, introduce rhythm work at 5K to mile pace with short intervals with long rest.  A particular favorite is 8 to 10 x 200 meters, starting at 5K race pace and gradually getting faster with each rep. Take a slow 200-meter jog recovery between each rep.

Training, regardless of the the event you’re getting ready for, is the act of balancing opposing forces. Where that balance needs to be and how to get there is the art of coaching. Understanding why that balance is needed is the first step. Now it’s up to you to figure out how to best apply it to yourself or your individual athletes.

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About The Author:

Steve Magness coaches cross country and track at the University of Houston, and also mentors many professional runners. He also maintains the blog ScienceOfRunning.com which is essentially a place for him to display his inner science and running nerd to the world. He owns a best of 4:01 for the mile and has a M.S. in Exercise Science from George Mason University.

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