what's the "healthy" ratio between the weight for leg extensions and leg curls?what if my ratio is "off"?

Question

answers from reputable sources only, please...

When I sprained my knee and needed to see an orthopaedist, he mentioned there was a correct "balance" between those muscles, one should be a little stronger than the other. I would guess I am a little too strong in the hamstrings compared to my quads, I can curl (235x8) a little more than I can extend (210x8), which I think is backwards.

For strength and mass-building, yes, I do start with squats and deadlifts. When I do extensions and curls, it's mostly for definition (but I've found that stairs are maybe better for definition (found out by accident after jogging up 9 flights at work after lunch for exercise for 2 weeks, and noticed I was getting way more "cut" than anything I did at the gym), so... I might cut down, or do higher reps at a lower weight and super strict form to go easy on my knees)

I asked the question mostly from a "healthy knees" interest... anyone know the scoop from a Physical Therapy standpoint?

Answer 1

my leg extensions are just a little bit heavier than my curls. (this is just me personally i dont know any real statistics, other than i lift 6 days a week)
Curls:100-110
Extensions:120-130
both on machine

Answer 2

thats an old meaure - it used to be 1:0.75 or better - that is you should be able to leg curl at least 75% of your leg extensions (one leg) - ideally this should be 90% or even 100%!

however this measure has not proved that good at avoiding hamstring injuries which is why it was first developed

the best thing you can do is make sure you are developing a very powerful posterior chain - lower back, hamstrings and glutes - the ratio in the leg extensions/leg curls is meaningless

by the way both are poor functional exercises - try squats and romanian deadlifts instead