Stop Trusting TSS Blindly

“TSS doesn’t tell you what you did. It tells you what a formula thinks you felt.” - Iñaki

Let’s be honest.

TSS is overused. Misunderstood. And often misleading.

“TSS doesn’t tell you what you did. It tells you what a formula thinks you felt.”
Start using real numbers. Start using energy.

It was built to give structure. But structure doesn’t mean truth.

Especially not for multi-sport athletes.

Especially not if you’re trying to stay healthy and seeking long term performance and compounding.

Why TSS Fails You

TSS means "Training Stress Score." It's a number. It estimates how “hard” a workout is based on your threshold. It was designed for cycling. It was a good idea 20 years ago.

Now? It creates more confusion than clarity.

Here's why:

• Two workouts can have the same TSS but totally different recovery costs.

• A 90 TSS run damages your body more than a 90 TSS ride.

• A trail run with heat and fatigue messes up your heart rate. TSS doesn't care.

• Swimming? TSS is just a guess.

My TSS chart from 2016 to last weekend…