The Book Of Longevity In Skateboarding: Chapter 7, gymnastics to strengthen legs
Jump stairs, there is nothing better than jumping stairs at least one day a week. You need to train your legs to withstand the impacts of skateboarding and doing tricks, then you train to withstand the impact... with impacts.
The first thing is to warm up properly without the skateboard and warm up properly with the skateboard. A stair session without warming up can be highly detrimental to our health. In fact, the stair session is usually the final part of our skateboarding session.
The stair training session is not about throwing yourself down the stairs trying a trick until you get it right. It's about doing basic tricks in a progressive and symmetrical way. You shouldn't jump what you don't jump in switch stance easily.
If your maximum is 8-10 ollie stairs it is appropriate to train with 4-6 stairs. If you don't jump stairs regularly, you can start with 1 or 2 stairs doing as many tricks as you can in switch and normal. If you don't like to jump stairs, you can do tricks upstairs, is also a good exercise.
It is important to symmetrize the session as much as we can, an asymmetric session is very harmful to our back, especially in the medium to long term. When you spend a lot of time trying a trick on stairs, it is good to try some of them in switch stance as well.
The video shows an example of a stairs session as an end session after an hour of skateboarding. There is exactly 30 minutes from first two trick line to the last three tricks line. In fact I'm currently working in adding switchstance tricks to the lines that come out in video.
At 46 it's a constant struggle between losing tricks from getting older and adding tricks you've lost from getting older.