Tom Platz, the man with the jaw!
I have tried doing lighter weights and believe me I had to start right back at the beginning! However I have never tried to rep out 50 on a light weight. To be honest I find that I fatigue very quickly on legs due to their deterioration. If I try to run they lieterally give way under me, or did do for a while. I will give it a go tho, thanks!
Leg extentions fit highly into my leg workout for the reasons you have already stated. Squats are definately out.

But the 45 degree press is slowing edging its way back in. Slowly but surely!