I usually go for a good half hour intensive spin session on the bike before starting any weights. However when doing leg extensions on a weight machine, I've noticed that although my legs don't feel the burn or strain, they are shaking like crazy when I'm lowering the weight.
Pushing it up is no problem but it looks like they're going crazy on the lowering stage of the rep.
My question is, is this a bad sign? I don't feel any sort of pain and I feel that I can add a good 15kg easily, but the shaking is actually creating a pretty big racket. Should I keep going or is the shaking mean that my legs are telling me to stop?