15/01/2026

Trained before a blood test? Here’s why that’s a problem

If you’re training consistently - first of all, respect. 

But if you’ve got blood work coming up, here’s something most people (and even many trainers) don’t know - your training can completely throw off your blood test results.

Let’s break down what happens, why it matters, and what to do instead.

How resistance training can skew blood tests:

These are all normal responses to training. But they’re not “normal” to your doctor if they don’t know you just crushed a leg day.

Cardio can also mislead:

So how long should you rest before a blood test?

Training type Pause before testing

Heavy resistance training 48 - 72 hours

High-intensity cardio 48 hours

Light/moderate activity 24 hours

How to prep properly:

Your blood test is only as good as the prep behind it.

You work hard in the gym, so don’t let a misunderstood lab result undo your efforts or scare you unnecessarily.

Stay strong and smart.