dittany, I suppose if you do them slower, than they would be safer....I just am really clumsy at times, and have dodgy joints anyway (tbh, am wondering if I am developing Rheumatoid Arthritis....because so many of my joints hurt so often, that incldues my finger ones...)
I think cardio burns energy more intense whilst you do it and for a couple of hours after, but can lead to muscle loss (if overworked, i.e. to out of breath, etc...) and weights burn less at the time, but for a longer period afterwards, aswell, as a higher muscle ratio means you burn more calories even in standstill and when not exercising...or some such thing...