If you’ve ever gone for a run and felt like it was way harder than it should be, you’re not alone. A lot of runners think the fix is just to run more, but that is only part of it. What really makes a difference is how much energy each step is costing you. That idea is called running economy. Two people can run at the same pace, but one might be using a lot less energy to do it. Over time, that adds up in a big way, affecting both performance and how you feel during and after your runs.

Oxygen delivery is the foundation of exercise performance. Through regular training, the cardiopulmonary system adapts to increase oxygen transport to muscles, improve waste removal, and support higher workloads. These changes are what allow you to sustain intensity and recover between efforts.