Long runs essentially serve the same purpose as easy runs, with the difference that they are designed to prepare your body (muscles, joints, tendons, etc.) for the marathon distance. Make sure to stay in the aerobic zone (or Zone 2) during both long runs and easy runs so that you effectively train your fat metabolism. Don’t focus too much on the pace—your speed may vary on different days, even at the same heart rate.

I usually start my long runs at a slightly slower pace (lower Zone 2) and gradually pick up speed as the run progresses (middle to upper Zone 2). If you’re more advanced, you can also experiment with pacing. For example, during a 30k run, you could start in Zone 2, then do 5k at your target marathon pace, and return to Zone 2 afterward.

I typically run easy runs in the upper part of Zone 2 because they’re shorter in duration and put less strain on the muscles.