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Running power

How to Measure Running Power From the Wrist – and What Can You Use It for?

We produce power as we run. Most of this power supplied by muscles is converted to heat and the small fraction that doesn’t turn into heat, propels us forward.

That’s called mechanical power, or in this case, Running Power. Power indicates how much force and speed a runner is exerting at any given moment: measuring running power can help you to understand how hard you’re truly working and how that relates to your full potential.

So, that’s why running power matters, but how to measure it – straight from the wrist – and what can you use it for?

Maximal aerobic power

Just like heart rate training, training with running power is based on power zones that can be determined by using maximal aerobic power (MAP).

Maximal aerobic power is the lowest power at which maximal oxygen uptake (VO2max) occurs during an incremental running test.

If you don’t know your maximal aerobic power, but you know your VO2max, you can update it to Polar Flow under “Physical settings” and we’ll estimate your maximal aerobic power based on your VO2max.

There’s also a test to estimate your maximal aerobic power:

  • Because MAP can be sustained on average for 6 minutes, you can estimate it with a 6-minute time-trial run.
  • To complete the test, run as fast as you can for six minutes.
  • After finishing the test, look at your average power which equates to your MAP.
  • Then update your MAP in your power zone settings.

Once you’re all set, it’s time to look at the different power zones.

Running power zones – Who and what are they for?

There are five power zones to help you achieve your training goals.

Zone 1: 55%–70% of maximal aerobic power

  • This zone is for easy runs or recovery sessions. Running in zone 1 builds up your basic endurance.

Zone 2: 70%–85% of maximal aerobic power

  • This is the marathon running zone. You should be able to maintain this level continuously for up to one hour. Alternatively, you can split your training into e.g. 4 x 1.6 km intervals.
  • Zones 1 and 2 are the bread and butter of your training. You should aim to spend most of your training in these zones. If you’re racing and your distance includes running in zone 2, reduce training in this zone during the competitive season.

Zone 3: 85%–100% of maximal aerobic power

  • Improves your maximal oxygen uptake (VO2max). In this zone, you should be able to complete 4–6-minute interval runs.
  • Zone 3 is for your training season. Include it in your training program for one month at a time.

Zone 4: 100%–115% of maximal aerobic power

  • Use this zone for long interval runs (150-600 m) that create a burning sensation in your muscles (as an indication of lactate accumulation).
  • Zone 4 is for experienced runners who prepare for competition. For the rest of us, it’s okay to be in zone 4, but a burning sensation in your muscles can strip the fun out of running.

Zone 5: More than 115% of maximal aerobic power

  • Improve your maximal power production in short interval runs (< 150 m).
  • Zone 5 is safe for all, but it may be difficult to achieve when running on flat terrain. A good alternative is to do uphill running sessions where reaching zone 5 is easier.

Measure running power from the wrist

With wrist-based Running Power measurement, you don’t need a separate foot pod or power meter – your sports watch automatically measures power from the wrist during your runs.

Running power is particularly useful for interval training and hill running.

Run intervals correctly

Interval training is effective and fun. However, to avoid bad habits, bear in mind the following advice.

During interval training, you should hold your running power constant between the intervals, or even slightly increase power towards your last run. This way you won’t be at the limits of your strength and will be able to maintain the correct running technique, which will help you avoid running injuries.

It’s okay to feel exhausted after each interval, but you should feel recovered before starting the next.

Note that your heart rate may increase as you progress towards your last runs (as in the example below). This is normal and depends on the length of each workout and recovery interval.

Example. Heart rate and interval training with constant (good) or decreasing (bad) power.

Run in hilly terrain

To obtain maximal power, you need to activate as much muscle mass as you can. This is easier if you run against a positive slope. You can’t attain maximal power when you run on flat terrain, not even at maximal speed.

Although you produce less power downhill than uphill, downhills put more stress on your muscles.

Running downhill forces your muscles to produce more force than running uphill. Thus, although you produce less power downhill than uphill, downhills put more stress on your muscles.

This may lead to muscle pain 24–48 hours after training (known as delayed-onset muscle soreness), but that pain is harmless, and your muscles potentially become more fatigue resistant.

Running in hilly terrain poses a different kind of stress to muscles than running on flat ground.

Overall, running in hilly terrain is a good alternative for all runners and poses a different kind of stress to muscles than running on flat ground.

Measure Running Power and have fun experimenting with it!

If you liked this post, don’t forget to share so that others can find it, too.

Please note that the information provided in the Polar Blog articles cannot replace individual advice from health professionals. Please consult your physician before starting a new fitness program.

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