A Practical Guide on how to Train With a Running Powermeter
By Evan Schwartz, Stryd Head of Coaching
Intro to Power and its Use
There is no denying that trends in training fluctuate over time while major tenets in training remain stable. Pace, distance, and heart rate are relatively consistent metrics that most runners are familiar with. The technology to interpret these values has evolved over time and the metrics associated with these training tenets allow runners to reach higher performance levels once they adapt to using these tools.
As technology continues to increase, new concepts emerge with much promise. Some technology requires users to invest a bit of time and effort into learning how to use interfaces and technological setup with the payoff in improvement after they adapt to their new-found gadget.
Simplicity in presentation and promise of improvement is what every brand would like to offer athletes keen on setting new PRs and making that next leap in performance level. One of these newer technological concepts, specifically in long distance running is power.
Power is a representation of how hard you are working at the moment and is displayed as a standardized metric called Watts. Using Stryd while training, you can measure your effort in real time, simplifying your training and race pacing, while setting measurable goals for improvement.
The goal of this guide is to simplify the practicality of training with a running power meter and explain the benefits that a simple tool can add to your training, planning, racing, and post-run analysis.
Incorporating Power into Your Training
So now you know Stryd delivers power as a measure of your effort, but how do you use it during a run? What ‘wattage’ should you run at for different workouts or for a race?
Your first 1-2 weeks with Stryd should be used to do a variety of runs at different intensities as the device gets to know your ability. With Stryd, the output is only as good as the input. In other words, if Stryd doesn’t have any quality efforts at different durations, it will have trouble suggesting the right target power for training and racing.
With the right data Stryd can tell you your Critical Power, and help guide your training and racing.
What is Critical Power?
Stryd uses your last 90 days of training to understand your current fitness, and uses that data to determine your Critical Power. Critical Power is the threshold at which the dominant type of fatigue your body experiences changes. This number is used to determine your optimal training intensities but requires have the following variety within the last 90 days for an accurate model:
- Short distance sprints or strides at max effort (10-30 seconds in duration).
- Medium distance runs with an uninterrupted duration of 10-20 minutes at race intensity.
- Long runs over an hour in duration.
Stryd will generate your CP after your first three runs, regardless of the variety in your running. If your first three runs are all easy runs, your CP will not have the accuracy needed to adequately calculate your training zones. Make sure to do the above variety early in your use of Stryd and continually incorporate the three types of runs into your 90-day training cycle.
Runs that contribute to your CP can be viewed in the Power Duration Curve, 90-day view.
What are Power Zones?
Once you have a Critical Power, you’ll see your power zones within PowerCenter and the app. Power zones help determine your training intensities and are broken into %CP. As your CP changes, you can quickly adjust your power targets to get the intended physiological effects. Continue reading for a breakdown of Stryd power zones and their intended physiological effects.
Understanding Power Zones
These practical zones are a guide on how to use power. Again, all of these will be based on %CP and can be broken down further into different ranges depending on your training intent.
Zone 1 Easy 65-80% of CP
1A) Post Interval Recovery: Easy recovery between intervals and cool-down - 50-65% of CP
1B) EZ Warm-Up: Easy warm-up component before intervals or racing - 65-75% of CP
1C) EZ Aerobic Running: Easy Aerobic Runs 75-80% of CP
Zone 2 Moderate 80-90% of CP
Endurance / Long Run: Typically, average power for long runs / overdistance (or sustained runs with higher intensity mixed in) Otherwise a grey zone for more standard length aerobic runs. 81 to 87% of CP
Zone 3 Threshold 90-100% of CP
3A) Extensive Threshold Stimulus: Sweet spot running. Tempo runs. Generally, sustained effort runs executed at the lower percentages of CP or, long (>=15 minute) intervals at the higher percentages of CP within this zone. 90-95% of CP
3B) Intensive Threshold Stimulus: Threshold work. Longer intervals and occasionally sustained effort running - 95-100% of CP
Zone 4 Interval 100-115% CP
4A) Supra Threshold: Suprathreshold work. Generally intervals - 102-105% of CP
4B) Maximal Aerobic Power Stimulus: Max aerobic work. Typically intervals (or occasional ‘time’ trials) - 106%-115% of CP
Zone 5 Repetition >115% of CP
5A) Anaerobic Power Stimulus: Anaerobic work. Short intervals or short time trials - 117-150% of CP
5B) Sprint / Maximal Power - Maximal Power. Sprints >150% of CP
So now you have all the numbers and math behind you. How do you put running power to use in your running? Continue on to read about use cases and see example runs in PowerCenter.
Example Runs with Power
For the sake of easier understanding, the below examples use a sample of runs from a male runner with a weight of 119 lbs, and a Critical Power of 228 Watts or 4.24 W/kg. You'll need to be signed into your Stryd account to view the activity.
Easy Run view the run here
The goal of an easy or recovery run is to maintain fitness and not overcook yourself for the next quality workout or next run coming up. Pace does not matter and should not matter. If you run varying terrain at the same exact pace but exhaust yourself because your effort is changing the whole time, you've just done yourself a disservice. Don't be glued to hitting an arbitrary time!
If a recovery effort for a runner is usually a 10:00 /mi pace on flat terrain, but they go run a rolling course with 500ft elevation gain at 10:00 /mi pace, this is obviously more stressful than a flat run. When you focus on running a specific recovery power you gain the ability to run at an even effort that doesn't put too much stress on your body.
Running easy runs or recovery runs at 65-80% of your CP ensures you are recovering and ready to go for the next planned workout or run. Our example runner targets a wattage of 149 to 183 on easy runs.
Threshold Plus Speed view the run here
Let’s look at some workouts now and give some examples on how to structure sessions to be consistent, maintainable, and specific to current fitness and running goals. Here is an example workout for a runner looking to target a Personal Best in the marathon. Their current CP is 203W. Here is an example workout to target their Threshold:
- 14-minute warm-up at 65-75% of CP - 131 to 152 Watts
- 30 minutes at 85-90% of CP - 172 to 182 Watts
- 3-minute recovery at 65% of CP - 131 Watts
- 3 x 30 sec strides at 130% of CP - 263 Watts
- 10-minute cool-down at 65%-75% of CP - 131 to 152 Watts
This workout targets a long duration (30 Minutes) at a submaximal level of Critical Power, and lets the runner practice running at a higher power target at the end of a Threshold.
Understanding Stryd Metrics
You might have questions about what is actually being recorded during your run, and how you can use these different metrics. Stryd records a variety of standard and unique metrics. What those metrics are and how they’re used can be found below.
Power is displayed in Watts (per second). It is displayed in real-time on your watch, and displayed as a post-run value in PowerCenter and the Stryd App. I personally like to compare Watts per kilogram in case of weight changes while training.
When you run not all power is dedicated to moving forward. As much as we would like to think that we are perfectly efficient, individual form and inefficiencies impact how much power is being expended aside from forward motion. Form power is that number that is not being used to move forward.
Form Power Ratio
Is the metric to look at when analyzing form power. The idea is that you want your Form Power to either remain the same or go down as your overall Power increases. The trend is the important thing to look at.
This is a simply explained metric. Cadence is the number of times the same foot hits the ground. Some people like RPM (rotations per minute, or that one foot being tracked) or SPM (total steps per minute). Cadence can be reported via accelerometers in a watch but foot tracking is always more accurate for obvious reasons.
Ground Contact Time
The time in milliseconds or ms that the foot is spending on the ground. This is a metric that goes along with cadence and some of the other biomechanical metrics. My suggestion is to feel out your own personal ground contact time in the post-run analysis and see if you are on the low end. If so, adding in specific plyometrics can help with efficiency.
This is the measure in centimeters or cm that the center of mass of the body moves up and down. Typical ranges are 5-9cm. Vertical oscillation will decrease when running uphill.
Leg Spring Stiffness
This is probably my favorite unique metric to track. Leg spring stiffness is the measure of the elastic forces in the lower leg, such as the Achilles and other tendons and ligaments/fascia. LSS divided by weight in kg allows for comparison across runners. The change in LSS over a run can be a signal for fatigue. The better a runner is, generally the more resistant they are.
If you have a Stryd Wind, the power you see on your compatible running watch or the Stryd app, is your total power. By toggling on ‘Air Power’ you can see what % contribution air resistance/wind had on your run.