The blurred line between cardio and strength training
Jul 9, 2025
Most people see it like this:
Cardio = running, cycling, swimming, jumping rope, elliptical, burpees.
Strength = dumbbells, barbells, push-ups, squats, pull-ups.
And the thinking usually follows:
I warm up with cardio.
My doctor told me only cardio, so no squats.
I need to lose weight, so cardio’s the best, right?
But here's the truth: the line between cardio and strength isn't that clear.
Try this:
Do 20-25 deep, fast squats. Heart rate up? Breathing harder? Cardio? Sort of.
Now flip it:
Crush 30 mins on the Airbike. Legs sore? Quads pumped? Get stronger? Kinda but not really.
What’s really going on?
All forms of exercise exist on a continuum with varying requirements for force, fuel and oxygen. So you can make one feel like the other by manipulating these 3 variables. Make strength low force and oxygen demanding enough, and it begins to feel like cardio. That doesn’t mean you should. Especially if you’re after efficiency and joint health.
Run 10k everyday to force your calves to grow or 3*10 on a seated calf machine? We know what we’re picking.
500 air squats in 10 minutes everyday for cardio? Your knees will not like you for that.
So how do you train smarter?
For cardio stick to low-skill, economical and cyclical movements like walking, stepping, running, elliptical, cycling and rowing. These stress the heart in a repeatable, controlled way.
For strength, focus on movements where your muscles fail before your heart does. 15 rep deadlifts may raise your heart rate higher than 3 rep deadlifts, but still won’t move the cardio needle enough for it to be a programming consideration.
Remember:
Every strength move has a cardio effect.
Every cardio move has a strength component.
But neither replaces the other.
You can make a strength exercise more cardio-like and a cardio exercise more strength-like but that’s a poor way to optimally stimulate either adaptation no matter how you slice it.
