Hi Hammock,
When in Jakarta, I met an old guy in Candradimuka dojo from Cingkrik Goning. I estimated his age was late 40 to late 50. (anyone who know who I meant are welcome to correct me).
And look at this guy. He is absolutely older than you.
Yes, some silat school can be hard on the thigh due to kuda-kuda (something like 'ma bu' or horse stance) but as far as I know, you won't be stand still in that posture in a long period of time (We are not guys from shaolin
). Some silat school didn't even have that tiresome posture.
There are also some sudden move from standing position to ground position that you may concern. But you won't do that kind of moves in the first day (or you may even never do that depend on which school you learn Silat).
My advice is, give it a try and know your limit. When you get tired or some of your muscle begin to strain, stop and don't continue training until it healed. Give your muscle rest one or two days. I did rest that the first time I do 'jejingkrikan' (hopping in one foot) from Cingkrik.