Running Economy and Power

When you are running at a constant speed, energy production and energy loss are in balance, i.e. your muscles produce energy at the same rate as it is lost due to mechanical friction, heat radiation, and air resistance.

Two people running at the same speed might have very different energy consumption rates, even if they weigh the same. An athlete who just started running might use 400 Watt at the speed where an experienced runner uses just 200 Watt.

Peter and Eddie

Imagine the following two athletes: When Peter and Eddie run together, they are equal training partners. Because of his bad running economy, Peter uses twices as much energy, but this is no problem for him, since he can produce twice as much energy. For both runners, 7-minute/mile pace is the fastest sustainable pace. In a race, both would finish in the same time.

Uphill and downhill

Peter and Eddie go running together. When they run at 80% of their maximum aerobic power, they use 800 Watt and 400 Watt, respectively.

Now they encounter a hill. To maintain their pace, an additional effort of say 150 Watt is required. This is precisely the problem with hills: regardless of running economy, the same amount of extra energy is required from all runners! So what happens next? Peter increases his effort to 950 Watt (95%) which is still within his limits, and maintains his pace. Eddie increases his effort to 550 Watt (110%) and fails after a while. He has to slow down by 10% to bring his effort down to 500 Watt (100%), while Peter runs on and wonders what's the matter with Eddie.

But it's not over yet. The next mile is downhill and both runners can decrease their effort by 150 Watt while maintaining their standard pace. Now Peter runs at 650 Watt (65%) and Eddie runs at 250 Watt (50%). To get his revenge, Eddie now suggests to double the speed and starts sprinting downhill at 500 Watt (100%). Peter tries to follow, but soon realizes that he cannot sustainably run at 1300 Watt (130%), and falls behind, wondering again what's happening here: Eddie just seems to be flying downhill.

Headwind and tailwind

A similar situation occurs when Peter and Eddie run into a headwind or are supported by a tailwind. Assuming Peter and Eddie are approximately of the same size and shape, wind increases or decreases the required effort to maintain the pace by a constant, just like a hill. Therefore, headwind is an advantage for Peter, and tailwind is an advantage for Eddie.

Treadmills

Running on a treadmill is equivalent to running with a tailwind where the wind speed equals your running speed. (This is quite a strong tailwind!) Therefore, on the treadmill, Eddie will be better.

A common myth is that running on a treadmill is easier because you are actually running in place and don't propel yourself forward. This is not true! Anyone who says that has not understood Einstein's theory of relativity! When you run on a treadmill, you do propel yourself forward - relative to the treadmill belt. And this is what matters.

Running economy and power

Runners with little power and good running economy are more sensitive to hills and wind. Runners with powerful muscles and bad running economy are affected much less, so relative to others, they are best when conditions are tough (incline, headwind) and worst when conditions are easy (decline, tailwind).

Now ask yourself, whether you are more like Peter or more like Eddie, and you will know whether you should work on your power or on your running economy.

Training Methods

To improve your running economy or your power, you have to train in a way that emphasizes the variable you want to improve. This means that in order to improve your power, you should add resistance, and in order to improve running economy, you should add support.

Additional resistance can most effectively be overcome by additional power, so your body will adapt by increasing your ability to generate it. At the other end of the spectrum, when resistance is lowered as far as possible, the remaining resistance can be overcome most effectively by improved running economy, so your body will adapt by adjusting your running form.

Eddie's Training Program - Improving Power

Peter's Training Program - Improving Running Economy

Select the right program

Eddie's training program improves power, but slightly deteriorates your running economy. Peter's program improves your running economy, but your power will decline a little.

Overall, the improvement in the one variable will outweigh the decline of the other variable, unless you select precisely the wrong program for you. This is what once happened to me: I did daily incline running workouts for four weeks. My running economy was bad when I started, but after the four weeks were over, my running economy was a mess. When I was running on the track, it looked like I was trying to run up a stairway and was always falling back down to earth with every stride, because the stairway wasn't there.

To select the right program for you, find out first what kind of runner you are. How do you do on inclines and declines compared to others? Your hill performance is a good indicator whether you are lacking power or running economy.

© 2005 Mark Dettinger
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