Stryd Fitness can be broken down into three measurements, Critical Power, Training Level, and Power Duration Curve. Critical Power defines your fitness, which adjusts your Training Level to challenge you appropriately, and your Power Duration Curve is a visual representation of the data used in your Critical Power calculation. These three measurements are designed to give you an idea of what your capabilities are based on your recent run data.
Critical Power (CP) is a representation of your current fitness measured in Watts. It is not scaled by your weight. 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 which trigger specific fitness gains and guide your race day effort.
For more information, please see the Critical Power support article.
Training level is derived from your Critical Power, and impacts the difficulty of Stryd's training plans. The Training Levels are based on the runner’s auto-CP (in W/kg).
There are 4 levels of difficulty.
Level 1: auto-CP < 2.9 W/kg, people running lower weekly volume, or individuals that need to take it easy on their body.
Level 2: auto-CP 2.9-3.5 W/kg, people who have a few seasons of training and race experience.
Level 3: auto-CP 3.5-4.2 W/kg, people who have trained and raced for a while.
Level 4: auto-CP 4.2 W/kg or higher, people who have experience training/racing and wish to train at a higher weekly volume.
For more information, please see the Training Level support article.
Power Duration Curve
Power Duration Curve (PDC) is primarily responsible for the accuracy of your Critical Power, however it impacts almost all of the features within Stryd's platform. Power Duration Curve represents the relationship between the power output a runner can sustain and the duration for which they can sustain it from short sprints to long endurance runs (up to five hours).
For more information, please see the Power Duration Curve support article.