Garmin Training Load vs TSS: what is the difference?

If you use a Garmin, you have seen Training Load. If you follow structured training, you have seen TSS. They measure the same thing — training stress — but differently. Here is how they compare.

What TSS is

Training Stress Score is an open, well-understood formula based on intensity (relative to your threshold) and duration. One hour at threshold is 100 TSS. It is transparent and comparable across sports and platforms. Full explanation.

What Garmin Training Load is

Garmin's Training Load estimates stress from heart-rate-derived EPOC, rolled into a 7-day acute load and compared to your longer-term load. It is proprietary — the exact numbers are a black box.

The practical difference

• TSS is portable and transparent: the same number means the same thing everywhere, and works from power or pace.
• Garmin Training Load is convenient (automatic on the watch) but locked to Garmin's ecosystem and heart-rate based, which lags on short hard efforts.

Which to trust

For day-to-day training decisions, a TSS-based model (CTL/ATL/TSB) gives you clearer, more actionable Fitness, Fatigue and Form. How that works. TrainCurve scores your workouts as TSS automatically — start free.