What is running power?

Power is the mechanical measure of running effort and intensity. Power indicates how much energy you are expending during the run and how fast you are expending it. Power is determined by calculating the amount of work done per unit of time as described by the formula:

Power = Work / Time

To better understand what power is we first need to get a better understanding of work. Work is equal to the force applied multiplied by the distance applied:

Work = Force x Distance

We can now substitute Force x Distance for work, resulting in the new expression of power as:

Power = Force x Distance / Time

Distance divided by time is also known as velocity, which is more commonly referred to as speed. If we substitute velocity into this equation we now have:

Power = Force x Velocity

This equation for power is where we would typically end while explaining how power is measured on a bike. On a bike, power is basically determined by multiplying the force applied to the pedals by the rate at which the pedals turn (cadence). However, running power meters do things slightly differently.

Stryd breaks down the above equation further. Force is equal to the mass of an object multiplied by its acceleration:

Power = Mass x Acceleration x Velocity

The mass of the object (you) is given and Stryd takes extremely accurate measures of your acceleration and velocity to calculate power, measured in watts. Running power considers speed , form, and elevation. Runners need quality training and guidance to succeed in their next race. Many runners struggle to find a repeatable and reliable way to attain high quality training and racing. Everyday there are questions that need correct answers: When should I run next? How hard should I run? Stryd answers these questions with a metric new to the running world: power.

This white paper evaluates the accuracy of the Stryd’s measurement of running power, ground time, and vertical oscillation, by comparing it with a lab grade force plate-based treadmill and a metabolic measurement system.

Pacing Workouts/Races

Steady-state workouts and races require the energy to be expended in a well-calculated manner. This is hard even for the most seasoned athletes. Most athletes go out much too fast at the start and pay the price in the second half of the race by having to significantly slow down. With a power meter, however, runners can pace themselves in a much more precise manner than with GPS readings or a HR monitor. GPS accuracy is dependent on weather, course conditions, satellite reception, etc. Heart rate is affected by temperature, caffeine, how much sleep you got and a whole host of other factors, whereas power is much more precise, these factors do not impact the calculated power. But proper pacing goes well beyond the common problem of going out too quickly at the start. It also eliminates the guesswork of pacing on hills, descents, and HR fluctuations. Pacing with power eliminates all of these and thus gives confidence to the runner

Why not heart rate, speed, or feel?

Power and speed are measures of output, they tell us what is being accomplished during a run. Heart rate and feel are input, they tell us what the effort is to create the output. Performance in the race is directly related to your output, not input. The input simply reflects what the runner is experiencing. The output decides who is going to come across the finish line first. Compared to speed, power is not affected by terrain change and actually capture the performance impact caused by running efficiency. Unlike speed, power will show the real-time energy costs of running up and down hills allowing the runner to accurately know their energy expenditure over the course of a run. Here in lies the greatest benefit of pacing with power, a single numerical target to follow the entire race. If you want to see the whole picture of the training, heart rate, speed and feel are still important metrics, it’s just that looking at the run through the lens of power makes better sense of all that you are seeing and experiencing from the other three, it makes them more relevant, clearer and more meaningful.

Stryd Running Power Meter New Gen (Wind Detection) 7,990 Bahts