I'm 51 (and there are quite a few forum members around my age), and I will be modifying some of the moves (not necessarily because of age, but because of my individual history of injuries and my own physical tolerance and limitations, and desire to keep functioning knees into my 60's/70's/80's and beyond!).
Even though the plyo legs workouts looks very high impact (and some moves are, as they are shown), that shouldn't be a deal breaker for the system.
1) You don't have to do the plyo legs workouts (they are alternatives to the heavy-lifting leg workouts)
2) modify-modify-modify. I think everyone should be their own personal trainer, and figure out what is right for them. For example, there's no way I jump OFF a step (WAY to much, and unnecessary, impact for me). For those 'jump-on/jump-off step" moves, I will jump on, then step off, and maybe even use a lower step (Cathe and crew show us a goal to reach for, but we should all do what we can while still challenging ourselves).
I don't tuck jump (that's just a move that doesn't work with my body and never did, even when I was 20!). Instead, I may do a jump squat.
If there's ever a move you want suggestions for modifying, just post in the Open Discussion forum or the "Workouts" forum, and other forum members can give suggestions.
3) you can go at a slower pace, maybe doing 2 reps to Cathe's 3 or 4.
As for STS overall: it will be a challenging, advanced training system, but it's also individualized. You lift what is challening to you (if that's 10# when Cathe's lifting maybe 40#, then so be it. You'll get better in time).
You may need more recovery than STS plans for (I find that after about 45, my recovery needs increased, and even Martina Navratalova sp? and other top athletes need more recovery time as they get past the 40-year mark or so). If so, then take it. There are no "exercise police" checking you out!
If you read certain posts and threads on the forums, you might sometimes feel that 'everyone' here is a hardcore, advanced exerciser, but that's not so. We all just enjoy being fit and healthy.
HTH!
