Training Stress Score (TSS)™
by Andrew R. Coggan, PhD

TSS™, which is modeled after Dr. Eric Bannister's heart rate-based training impulse (TRIMPS), takes into account both the intensity (i.e., IF™) and the duration of each training session, and might be best viewed as a predictor of the amount of glycogen utilized in each workout. Thus, a very high TSS resulting from a single race or training session can be used as an indicator that one or more days should be scheduled off.

For example, while individuals tend to differ in how much training they can tolerate, depending on their training background, natural abilities, etc., the following scale can be used as an approximate guide:

 - Less than 50 - very low (recovery complete by following day)
 - 50-150 - low (recovery generally complete by following day)
 - 150-300 - medium (some residual fatigue may be present the next day, but gone by 2nd day)
 - 300-450 - high (some residual fatigue may be present even after 2 days)
 - Greater than 450 - very high (residual fatigue lasting several days likely)

As well, the cumulative TSS per week or per month can be used to help identify the maximum intensity and volume of training that still leads to improvements, rather than overtraining.

Normalize Power (NP)™, Intensity Factor (IF)™, and Training Stress Score (TSS)™ are all registered trademarks of Peaksware, LLC.