# Formula to Calculate HrTSS

Does anyone know the formula to manually calculate hrTSS? I want to make a training plan consisting of trainerroad workouts, running workouts and squash matches, however the running and squash will need to assessed using hrTSS. I use a heart rate monitor for all the activities so will know the average heart rate and time in zone so i think i have the required component data to calculate the TSS using hrTSS.

I’d like to do this manually rather than paying for TrainingPeaks and then input the resulting TSS figures into TR.

Any assistance would be greatly appreciated.

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Can’t help with the formula, but I get hrTSS from the free version of Training Peaks - i use it for rides without power and my running and input into TR!

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If you record heart rate, you know your maximum, rest, and threshold (LT) heart rate for this kind of activity, and post these activities on Strava, you can use the Elevate extension to calculate its “HRSS”, which is more or less the same as hrTSS.

HRSS_activity = (TRIMP_activity) / (TRIMP of one hour at LTHR)

TRIMP = sum( dt * HRR * 0.64 * exp(k * HRR) )
HRR = (HR - HR_rest) / (HR_max - HR_rest)
k = 1.92 for men, k = 1.67 for women

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I was using Elevate to track training stress based earlier this year. I liked it but somehow my data got screwed up & I got injured around the same time so I ended up not resyncing.

Also, ought to be mentioned that the version I was using was a Chrome plug in. Not sure if there are other versions available now.

Chrome plugin. Note that settings don’t sync between two browsers, if that applies to you.

All you need for Elevate to calculate HRSS for individual workouts is to have the heart rate Athlete Settings (min, max, LT). The HRSS will then appear in the workout summary, and you can copy it anywhere as an equivalent to (hr) TSS.

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Thanks for the information about the elevate plug-in, but that’s not really what I’m looking for.

I want to be able to plan workouts and a training plan by predicting the training stress prior to doing the workout, not record it after having done the workout.

For example, I want to do a 1hr long run at steady state in upper zone 2, which for me is around 143bpm. But I don’t know how much stress that equates to.

The next workout is 4x1 mile intervals at 7:00min mile pace with 2 min rests between and a warm up and cool down in zone 2. What stress does that equate to?

From what I know the only way to predict the tss for those, is by using a formula to calculate HrTSS.

Thanks so far.

For running I use rTSS rather than hrTSS

The only way to estimate this is to estimate what your heart rate is likely to be in those intervals and rests. Do you have data from comparable runs from which you can estimate a “typical” heart rate for typical interval / rest patterns?

You also need to know HR max for running, LTHR for running and resting HR.

If so, then you can use the formula that jpowers provided. To lay it out [assuming 45 minute workout, with 5 minutes warm up and 6 minutes cool down]:
1 In column A enter HR rest [A1], LTHR [A2] and HR rest [A3].
2 In column B, enter the estimate HR for each second of the run you intend to do [ie, 60 * 45 numbers].
3 in Column C, calculate HRR from the formula of jpowers: = (HR - HR rest) / (HR max - HR rest) [6045 numbers].
4 In column D, calculate HRR
0.64exp[kHRR], with k = 1.92 for men, k = 1.67 for women [6045 numbers].
5 Calculate the sum of those 60
45 numbers. This is TRIMP.
6 In column E, cell E1, calculate LTHRR = (LTHR - HR rest) / (HR max - HR rest).
7 Calculate E2 = LTHRR0.64exp[kLTHRR], with k = 1.92 for men, k = 1.67 for women
8 Calculate E3 = TRIMP of one hour at LTHR = 3600
E2.
9 Estimate HRSS = TRIMP / E3.

Your actual HR history in the workout will be different from this calculation, of course.

If you’re planning future workouts, you can use the estimates by zone in the linked article about estimating training stress.

You could also use a free TrainingPeaks account and their workout builder.