No matter how trained you are as a walker, climbing stairs is not easy for anyone.
This is because you use your muscles differently during stair climbing than during normal walking or running. You move against the force of gravity and build up your strength and power.
By regularly training for stairs you will eventually be able to run at a higher pace for a longer time without feeling acidified. It also trains your glutes, thighs, calves and even your abs.
After a 10-minute warm-up, walk up the stairs at a fast pace for 20 to 30 seconds. Then walk back down slowly. Repeat for 20 to 30 minutes.