This is very easy running. You can talk the whole time or even sing, and your breathing barely changes. Your legs feel light and loose, and it should almost feel too slow. Recovery runs help your body bounce back from hard days without making you any more tired.

This is your everyday pace. You can talk in full sentences without gasping, your breathing is a little deeper but steady, and your legs feel relaxed like you could keep going. Easy running builds your endurance and a stronger heart, so most of your running should happen here.

This feels comfortably hard but still in control. You can only get out a few words at a time, your breathing is deeper and quicker, and your legs are working without any real burning yet. Because it sits just below your hard effort, you build a lot of fitness here without wearing yourself out.

This is hard but steady, right at the edge of what you can hold. You can manage a word or two, your breathing is deep and fast, and your legs have a steady burn you could handle for about an hour in a race. Training here raises the effort you can hold for a long race, so you can race faster before you slow down.

This is very hard. You can maybe get out one word, your breathing is all out, and your legs are burning and heavy after just a few minutes. You run it in short reps with rest in between because you cannot hold it for long, and it builds your top speed and your engine.

This is fast and smooth. The reps are short, so even though you cannot really talk, your breathing comes back fully between them. Your legs feel quick, springy, and powerful, with fast smooth turnover. This trains your speed and running form, so you stop while you still feel sharp instead of worn out.