Running Power Meters are beginning to roll out across the running and triathlon scene. While the technology has been developing over years, the application is still in its infancy across the general population of users. Power meters have been around in cycling for a long time and coaches and athletes are quite developed in their knowledge and data analysis, but unlike cycling the metabolic costs of fatigue and inefficiency are high for a weight bearing activity like running.

With the lack of knowledge among the general running population on how best to use running power meters for monitoring and improving performance, I think that Stryd is making some good headway into developing athletes knowledge of running with power.

So why run with power?

I guess this is the million dollar question. Like cycling, using power data is a more sustainable and reliable measure of energy output. Other metrics like heart rate can vary during exercise based upon a range of conditions whereas power is a consistent measure with the data relatively unaffected by external conditions.

Here are my thoughts after initial testing:

The Stryd Concept

Stryd is a small foot pod that attaches to your running shoe, it has smart Bluetooth and ANT+ connectivity. The Stryd power meter (as with other running power devices) are not measuring the physical power that your muscles apply to ground. Instead is uses the knowledge of Newton's third law of motion to determine the power being exerted from the ground as you move. Stryd does this by using a series of accelerometers recording data across a variety of planes of motion, this combined with your weight and speed, can generate a power value along with a range of other running metrics.

While the foot pod is an easily accessible and simple to use device, much like a single sided bike power meter it is generating its data from one side of the body.  Also it's important to mention up front that initially most analysis is going to be done post run until you discover how best to use the data.

The Device

The foot pod is small and light, designed well for the needs of running. It attaches to your shoe with a neat little plastic bracket so is easily transferable if you use multiple shoes. Due to its large amount of data processing of various metrics the requirements for power are greater than a standard coin style battery. The pod is usb rechargeable and lasts around a month (depending on use). It comes with a wireless charging unit that the pod sits on to recharge. You can monitor the battery life using the Stryd app.

How good is a foot pod? Unlike the chest strap or pod clipped to the shorts, the foot pod has many advantages. It's location on the shoe means that metrics like cadence, stride length, leg stiffness, speed are measured very accurately from this location. Comfort is not an issue with the foot pod, unlike a chest strap, although the chest strap is more useful for vertical oscillation data if you find that important to you.

The Set Up

Once the foot pod is on your shoe connection is fairly straight forward. You will need to download the Stryd app to check firmware and updates and for data capturing during runs. You can link your Stryd account to other platforms easily (Garmin connect, Training Peaks).

Before you begin your run you will also need to connect the Stryd pod to your chosen device. For my Garmin 920xt you need to download the Stryd application from Garmin IQ so that your power data can appear on the watch. Once connected you never really have to worry about it again as connection is automatic once paired for the first time. The updates by Stryd now allow for power smoothing to be displayed during your runs (3 second average, 30 second average).

Device compatibility can be found here (https://store.stryd.com/)

Power Analysis

So now what do I do? This is probably the biggest question on most peoples mind and probably something you want to consider before purchasing. My advice is run for your first week or so as you would normally, don't have your power metrics showing, record the data over this period and come back at the end of the week to review. The key part of running with power is to assess what the data means for you and how you might use it going forward to improve aspects of your run that will make you more efficient or produce better performances. This can be done in a few ways which I will suggest later.

Here's a grab of some of my initial data:

Stryd PowerCenter is where your account is housed. I like to do my post run analysis from here, although I do monitor it in Training Peaks as well. The benefit of using the Stryd PowerCenter is that the data, graphs and overlay options will give you much better analysis of your run.

The picture above was an overview of The Mosman Pace Athletic Run Club, essentially an aerobic run which included a group warm up, 6 hill repeats and a group cool down. The metrics shown in my overview:

Pace, Time, Average Power, Form Power, Cadence, Distance. I use the graph to look at various metrics from my easy running and my hill intervals. What you will need to decide is what metrics you wish to focus on and which to disregard.

If you click on the drop down menu on the top right hand side of the graph you can include/disregard other metrics like vertical oscillation, ground contact time, leg spring stiffness etc.

Monitoring Training

One of the most useful aspects I find with Stryd and using the Stryd PowerCenter is to plan and monitor my training load. Stryd have developed RSS (Running Stress Score) to help assess the metabolic costs of different types of running workouts on the body. Much like TSS (Training Stress Scores) that are commonly used, RSS incorporates power data to assess and inform an athlete of how hard a training session may have been and give you insight to how much recovery you may require.

Essentially: RSS = 100 x training duration x (Power/CP)^K

• CP -Critical Power/Threshold Power (easily testable/ estimated)
• K - The K factor accounts for varied stresses that different intensities have on the body during running (essentially the energy costs of different paces)

There is a good little blog on Stryd about RSS - http://blog.stryd.com/2017/01/28/running-stress-score/

How can you use this data for training?

The challenge for you, your coach or the general population is to decide where your running focus lies and how Stryd and its power data could support that.

To start I'd approach this in two ways:

1. Power/Pacing: You/your coach has a good idea of your running weaknesses: use the data during and post run to assess the part of your running that aligns best to the needs of you individual running goals to plan training accordingly, set session goals and map improvement.

For example one of the best uses for running power is to establish specific power-to-pace ranges. If you are working to increase your ability to hold a certain power at a specific pace, you can assess similar intervals/runs to see where you are fatiguing and if you can make form or fitness changes to maintain power/pace for longer in the future. This would be a good opportunity to focus on your form power data (efficiency and the metabolic cost of fatigue).

2. Focus on specific metrics: Use the data from your runs to find the starting point of your improvement. If your form power is particularly high (which is bad/displays fatigue) in certain running situations or you can see that your leg spring stiffness is deteriorating during a run this may be an area for improvement? You may seek to make adaptations to your training load, strength and conditioning or pacing to see if this can be maintained more efficiently as these things improve.

There is a good article on the Stryd Blog on Leg Spring Stiffness and Form Power -  http://blog.stryd.com/2016/11/04/run-faster-with-stryd-part-two-2/

Overview

I think I could talk about this device all day, I'm a fan! I'm by no means a data geek, but I do see some good training and racing developments coming out of using running power and Stryd seems to do it very well. They will be the first to admit that there is always work going on to improve software and continuing to develop information and interaction with its users to make this device more than just a part time training tool. My advice is to think about how you will use it and understand why you want it before you buy, but I'm sure if you do you won't be disappointed.

Purchasing

You can order Stryd direct from their website for worldwide shipping. They come in at $199 USD which is quite affordable. Currently, all purchases of Stryd from our site will receive a FREE copy of 'The Secret of Running', by Hans van Dijk and Ron van Megen.