Cross trainers. Any advice other than don't.

[TotallyEggFlipped]

My mum has decided she needs a cross trainer. We have been unable to convince her that it won't be used (like the exercise bike, regular bikes, rowing machine etc etc), because she's retired now and convinced that she has the time and that's all she needed.

So. Any advice/tips on what we should be looking for? We'll be looking on gumtree etc, but no idea what makes/features to look for/avoid.

Thank you.

Don't.

Ahem.

Avoid like the plague: any cross-trainer that takes the feet out sideways in a kind of skiing movement. They are awful things, absolutely terrible for the knee ligaments.