Bending knees in elliptical machine

paprad

I was chugging along on the elliptical today when this neighbour of mine stopped to tell me that I should keep the knees bent even when the pedal is at the lowest - he said that I could wear out my knees if I don't keep them bent, I tried observing what I was doing and I got totally confused. I suspect I am straightening one leg as it descends but not fully - should i be alert to this and going a little lower so that both legs are always bent?

kaned_ferret

I always straighten my legs on my elliptical.. the action is probably most similar to riding a bike, I straighten my legs on the downpush there as well.. *shrugs*

paprad

I always straighten my legs on my elliptical.. the action is probably most similar to riding a bike, I straighten my legs on the downpush there as well.. *shrugs*

me too! that's the exact analogy I thought of too and now it's got me all confused about what I've been doing intuitively. yesterday I became so conscious of my knees that I screwed up the rest of the workout.

I recall reading that the seat of the bike should be adjusted that the leg, when fully extended, is just short of being locked - so in a bike I guess we can fix things to prevent locking. in an elliptical one would need to be in a state of permanent semi-squattedness to ensure that, no?

heybales

Well, I did see this posting and thought it sounded interesting for a question.

The traditional way to get your seat height right on the bike is pedal until your rear is where it normally would be, then put heels on pedals and at furthest extension, knee is straight and hips don't rock.

Now when you put your forefoot back on it, there is a natural bend to the knee, and load is shared between quad and glute/hamstring.

Doing 90 rpm with even a bit of tension would be terribly stressful to the knee if it went straight.

Now, you stand up and do slower RPM for a hill, your knee may be straight but you are riding your weight down.
There is another way of doing hills if light and you keep the 90 rpm up. And that is basically pretend you have virtual saddle farther forward, so almost pedaling exactly the same, same bend to the knee.
Again, because it would be hard on it that style letting the knee go straight.

I've done the elliptical both ways too, and I see people do it both ways.

The reason for not wanting to go straight legged if you keep a high rpm would be same reason, hard on the knee.
But steeper incline and slower rpm you could, and kind of ride the weight down for a long portion of the distance, but just as on the bike, you bend before hitting bottom.

The classic method used on the bike at the bottom of the stroke applies to elliptical too, to enhance the point where the motion changes.

It's the dog poop scrape. But you can pretend it's mud too. Same feeling and motion as if scraping a mess off the bottom of your shoe, you pull back lifting near end. You wouldn't do that with straight leg, because to properly engage the glute and hamstring knee must be bent, or you are not getting any lift to it at the back part.

Really if keeping the rpm around 90 like the bike and running is usually optimum, it's hard to have enough time to lock the knee.

If going slower with more tension, which can frankly be harder on the knee anyway, I'd just be aware if you have it really locked, and is it still locked at the bottom when the motion is changing on you to going back. While is is less impact than running, that bottom part is close, and you've never land knee locked out.

paprad

Thanks heybales - that's really detailed and I am going to think through that a few times till I get it.

I guess it would be easier on the bike, once the correct height is worked out, the seat-pedal distance is fixed, so the leg cannot straighten, unless one gets off the seat, as you said, for hillwork. But on the elliptical there would have to be a conscious lowering to keep knee bent - wouldn't that keep quads in a state of permanent flexion, and hence, more strained?

How about food position - is it okay/desirable/bad to roll from ball of foot to heel of foot (on elliptical, that is), I figure that if there is more weight on heel, there is a tendency to lock knee, but if the weight was more on the ball, there would be a more automatic bend.

heybales

Is flexed and working strained though? When you run as pro's do, every land on a leg is taken with bent leg and shock absorb by quad.
Since it's at almost total extension of leg, or contraction for the quad muscle, it's also the point where it's easiest for the muscle.

I think the foot option again depends on rpm and tension setting.

Low tension for 90 rpm, probably flat foot to ball before pushing off is about all that's possible. If you tried to go straight legged with heel total support in there you'd be banging the knees when straight.

High tension 75 rpm, probably could hit the heel, and ride the slope down with straight knee, then bend at the bottom for the pull-pack on ball of foot. And that's only with high grade where you have a slope to take down.

paprad

Thanks heybales. Much to think about!