The following is Part 3 of our three-part series showcasing the difference between running with power or with pace. See Part 1 and Part 2 here. These excerpts come from Jim Vance’s book Run With Power.
Let’s begin today’s discussion by taking a look at this illustration:
A Workout with Pace and Power
Now let’s try a workout with pace and then with power. Pretend you’re training for a marathon with a goal finish time of 4 hours, which is 9:00 min/mile pace. You’ve just run a 2-mile warmup and plan to run a 2-mile cooldown.
Today’s workout is a strength workout (borrowed from Hansons Marathon Method):
6 x 1 mile at 10 seconds faster than race pace with ¼ mile jog recovery
Based on your goal finish time, you would run the mile intervals at 8:50 min/mile pace.
There are dozens of ways this hypothetical workout could go:
- Maybe you love training on treadmills so you could perform this workout with utter precision and control.
- You might live near a community track or in a pan-flat, windless area that’s always 65 degrees and be able to perform this workout exactly as prescribed.
- You might run on the actual race course for your upcoming marathon, making this workout nicely specific.
- You might live in an area with lots of rolling hills, every one of which distorts the intended intensity of the workout above.
Chances are, you run where you live and that means you have at least some variation in the terrain and weather. In any case, how would you get the most out of this workout? If you’re like most runners, you’d ignore all the variables and run exactly 6 x 1 mile at 8:50 min/mile with ¼ mile jog recoveries. Here’s how that might look:
- On the treadmill: You nailed the workout, performing it exactly as described. But is it worth doing all your workouts on the dreadmill?
- On ideal running terrain: Congratulations on your selection of hometowns! You nailed the workout.
- On the actual racecourse: In this case, your race day plan is probably a tempo run, not intervals. But kudos for specificity!
- On rolling hills: You could be in trouble. On the uphills, you were holding your 8:50 pace, meaning you were working much harder than the workout intended. On the downhills, you were just coasting along. Does it all even out? No, not really. Your workout called for a intensity and duration equivalent to exactly 6 x 1 mile at 10 seconds faster than race pace with ¼ mile jog recovery. You nailed the duration, but your intensity was all over the map.
Now put on your power meter and try this workout again. Using a power meter, this workout could be written this way:
6 x 1 mile in Zone 3-4. Recover between intervals with 2 min. jog/walk in Zone 1-2.
Here’s how this workout would look:
- On the treadmill: You nailed the workout, performing it exactly as described. Now you also have feedback (and hard data) on your running form efficiency and can compare it to your pace, RPE, and heart rate. Again, is it worth doing all your workouts on the dreadmill?
- On ideal running terrain: Kudos on your choice of hometowns! You nailed the workout and you have a lot of power data you can use to improve efficiency and monitor performance over time.
- On the actual racecourse: In this case, your race day plan is probably a tempo run, not intervals. But kudos for specificity! Your power meter gives you hard data on exactly how hard you’ll need to work on race day on this section of the course to hit your goal time. This is invaluable knowledge.
- On rolling hills: You nailed the workout. How? You adjusted your pace going uphill to stay in Zone 3 or 4. You increased your pace going downhill, too, to maintain the ideal intensity of Zone 3 or 4. Same with the recovery intervals. In this example, your power meter enabled you to perform this workout as written, despite the terrain.
In all these scenarios, you were able to perform the workout correctly, but three of those scenarios are pretty unlikely. Most runners enjoy running outdoors. Most of us live in places that aren’t pan-flat and windless. And a major difference in using a power meter is that you know you did the workout correctly. It eliminated all doubt, even on the hilly terrain.
Windy Hills Are Just One Limited Use for Power
The power number on your wrist gives you instant feedback on your workout intensity and your running form efficiency, but it’s just one way to use the power meter for running. The power meter can unlock your potential in vastly more powerful ways as you use it over time to monitor changes in your performance.
In all the workout examples above, you’ve taken a baseline measurement of your direct work output for a strength workout of this structure. By boiling down your workout intensity to a single number, your wattage, you can compare it to the other data, like speed, to begin understanding yourself as a runner in all new ways.
For example, perhaps you ran your early intervals with a higher speed per watt ratio. This means your earlier intervals were more efficient and your form broke down a little toward to end of the workout. Why is this? Only you or your coach can interpret the data your power meter reveals. Maybe an old injury was bugging you a bit in later intervals. Your power meter shows that it adversely affected your form, so maybe it’s time to revisit therapy to heal that injury.
Efficiency: Speed per Watt
Jim Vance’s concept of “Efficiency Index” is a simple ratio that GPS watches cannot measure. The EI measures the ratio of your speed against your power output. Runners who can squeeze more speed out of the same power have become more efficient runners, and as well all know, efficient running form can be a critical determinant of race performance, particularly in longer race distances.
Measuring Your Training Matters
If you care about your running performance, you need to care about how you measure your workouts. Put simply, there’s no better metric for runners than power. Pace, heart rate, and RPE give us part of the picture, but adding power to those measures gives runners and coaches unprecedented insight in your workouts and your fitness.
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