Quad strengthening exercises

I need to strengthen my quads, but due to dodgy knees I am not allowed to do squats or lunges (did them in a class once and couldn't run for 6 months afterwards).  Can anyone suggest any exercises that could help me?

Thank you!

I don't see how you can work your quads without involving your knees to some extent, but maybe using the leg extension machine in the gym would be OK?

If you can tolerate it, the best exercise would be a "high step up" (your knee should have a 90 degree bend when your foot is on top of the box/step). Not only does this help quad development, it is also a single leg exercise which running is essentially, and it improves balance and co-ordination.

 If you look at the knee bend in a runner there is probably no more than 30 degrees bend during the take off phase, so there is not real need to squat deep. Even doing a partial squat would be useful and may not cause you too much discomfort.

 There are plenty of exercises out there, but these two would work best for starters.

Hi Dippycat, I did a bit of internet research when I hurt my knee a while ago and came across this site which I used to rebuild strength. Knee Exercises

After a couple of weeks I really did notice the difference

Thanks for all those ideas everyone.  There's loads there for me to try!  I will give them all a go and see which works and next time I see my physio I will ask her too.

 Thank you!