What is Training Load and why is it important to keep your performance data up to date?

How is training load calculated?

The formula for training load is quite simple and is based on TrainingPeaks' TSS calculation. However, we have made some minor optimizations.

The training duration (t) in hours is multiplied by the square of the intensity factor (I):

How does enduco determine training effort and what does the factor (I) mean?

At enduco, you regularly complete performance tests that measure your current performance data. Important values such as your FTP (Functional Threshold Power), FTHR (Functional Threshold Heart Rate), or your TPace (Threshold-Pace) are measured and updated. This data forms the foundation for training load calculation. That's why it's crucial to keep your performance data up to date.

Each recorded intensity is compared to your threshold value to determine the intensity of a training interval for you. The intensity factor (I) equals 1, for example, if you were to maintain your threshold intensity (FTP/FTHR/TPace) for 60 minutes. This results in the following factors for the different intensity zones:

• Active Recovery: 0.55

• Regeneration: 0.65

• Tempo: 0.83

• Threshold: 1

• HIT: > 1

Two Examples

• 90 Min in the Regeneration intensity zone:

• 60 Min in the Tempo intensity zone:

Additionally, intensity is expressed as normalized intensity (e.g., Normalized Power, NP) to better represent intense peak loads in training compared to pure average power output. The goal of NP is to estimate the "perceived difficulty" of a workout more precisely than average power alone can do. This proves particularly useful for uneven training sessions, such as intervals or intense sprints.

A brief overview of "Normalized Intensity": Normalized intensity is calculated using a sophisticated algorithm. This takes into account the fluctuations and variability of your power, heart rate, and pace during training. The process works as follows: Power is measured in short intervals (typically 25 seconds), raised to a power, averaged, and finally recalculated using the fourth root. The result? Normalized power heavily weights power fluctuations and places special emphasis on more intensive training phases. In Figure 1, you can see the effect normalized power has compared to the raw values from the power meter.

Fig. 1: From Clarke, Skiba (2013). Rationale and resources for teaching the mathematical modeling of athletic training and performance.

This allows us to assess how intensive a training session is for you. Your training can be optimally adjusted so that it is precisely tailored to your performance level. Therefore, it is of immense importance that your performance values are always up to date. If your performance values deviate significantly from the actual value, enduco could over- or underestimate a training session. This would result in your training being "evaluated" with too much or too little training load.

Why is the training load important?

The training load forms the basis for your current fitness, form and fatigue. These parameters provide information on how much training volume you can currently manage and what your current form is like. Ultimately, they can be used to calculate the training volume you need to optimally compete in a specific competition.