Running Power vs Heart Rate vs Pace

If you're wondering about Running Power vs Heart Rate vs Pace, then let me tell you my experience.

When I first took up running 5 years ago, I ran by pace. Pace was the golden number which showed me if I had run hard enough or fast enough. Everyone compared paces, me included.

Roll on a couple of years and that pace number became my nemesis. I was always chasing a faster pace and the more I chased the more I got weary and the more I got injured. It took 3 injuries before I finally decided that something had to change.

That's when I found heart rate training. Forget your pace and train by your heart rate I was told. With this method you will be running at a defined heart rate. If you are feeling run down, lacking sleep, sick etc, your heart rate will tell you and so will force you to run slower. Your heart rate will dictate your speed and not the other way round.

I love this method of training, it has kept me injury free, made my runs more enjoyable and yet I am still able to run fast if I needed to.

However I recently came across another metric: RUNNING POWER.

If you are a cyclist (not me), you may have already cycled by power, but for runners it is a very new metric. The more I read about it, the more it made sense for runners and the more I wanted to try it out.

How does running power work:

A power meter measures the work that you are doing in watts. Using  accelerometers, it monitors your body movement (forwards, sideways and upwards) to calculate a power output in watts. The higher the watts, the harder that you are working.

It also takes into account your weight so that a lighter person will need to produce less watts than a heavier person in order to produce the same speed.

  1. You need to wear a power meter. I use the Styrd Power meter which attaches to my shoe.
  2. You establish a baseline by doing a race or power test. 
  3. This baseline will allow you to set up power zones just as you might do with heart rate zones or pace zones. If you are using a Stryd, it will predict training power zones and your capable race power for a target distance.
  4. You link your power meter to your running watch and then you run following the power zones or the predicted power number.
  5. After each run or race, you can analyse your run to see how much power you used on each segment, hill climb, race etc 

It all sounds pretty straightforward except you are probably wondering why not just stick with heart rate and not bother to buy yet another piece of running kit.

For me, the biggest advantage is that power is instant. As I run, my watch shows the exact power/work that I am doing at that exact moment in time. This makes sure that I am running at the correct power in order to achieve my planned training run or race.

Heart rate, great as it is, tends to lag and takes a while to catch up with your effort. At the same time it can jump all over the place if you are excited, stressed, tired or have had that extra cup of coffee.

As for pace, is not reliable as you could well be over or under exerting yourself. Most people tend to run way too fast in training and way under estimate what is an easy effort pace.

Running Power vs Heart Rate vs Pace

As a couple of examples, I recently did some intervals during training. As you can see from the graph below, when I was running hard, my heart rate took some time to follow. If I had been going purely by HR, I would have kept on pushing until I got into the prescribed HR zone. That would have been a mistake and I would probably haver over done it.

Intervals - Running Power vs Heart Rate vs Pace
I also did a half marathon race last weekend. Actually it ended up being 24km as I got lost. No surprises there!. It was hilly and mostly on track, very muddy with rain and wind.

If I had raced by HR, I would have probably had to walk round as my HR was high due to the excitement, stress and the conditions. If I had run by pace, I think I would have blown up, as the hills were pretty hard work.

Instead I ran by power (well I tried to, as I am still quite new at using Stryd), which meant that I exerted the same power/effort whether it was a flat, downhill or uphill. This meant I ran the whole race at the same exertion so I wasn't wasting energy climbing or descending the hills too hard.
Race - Running Power vs Heart Rate vs Pace
What I was really happy about was that I felt pretty good throughout the race as I was running what I was capable of doing and keeping an even power. Normally I set myself a pace based on what time I "think" that I can finish it in. I then start to too fast despite telling myself not to and struggle and hate the rest of the race.

So much as I love HR training, I am going to keep going using my Stryd power meter for now. In fact my power zones are not that much different from my HR zones in terms of the pace that I end up doing, just maybe a wee bit faster.

I think that there is always going to be a battle between Running Power vs Heart Rate vs Pace but I am becoming more and more convinced that power is going to be the one that helps you train and race smarter and which will get you to the finish line feeling that you've done your best.