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Interesting Leg Extension Discussion

post #1 of 21
Thread Starter 
I realize that telling people about the problems associated with leg extensions is opening up a can of worms, since for some people, it is the equivalent of telling someone that there is no such thing as Santa Claus. However, in the interests of safety and efficiency, take a look at this:

http://www.t-nation.com/readTopic.do?id=1306675

Here a few of the most interesting key points:

Quote:
Escamilla et al. (1998) found that the squat generated twice as much hamstring activity as the leg press and knee extensions. (2) Hamstrings recruitment can be advantageous in enhancing knee joint stability and building strength and functional capacity with hip extension. And, for those of you who've ever been involved in an anterior cruciate ligament (ACL) rehab program, you'll know that the day you can get hamstrings and glute soreness after quad-dominant squatting is the day that you know the athlete is kicking on all cylinders and you've done your job!
I found that enlightening, since in my early stages of ACL rehab, I was unable to feel the hamstrings or glutes during squats, but now I can. YAY!

Then there's this:

Quote:
These researchers also found that open-chain exercise (leg extensions) produced more rectus femoris activity while closed-chain activity (squats) increased recruitment of the larger, more powerful vasti muscles. (2) Stensdotter et al. (2003) verified these findings and also looked at onset of recruitment in more detail. They found:
In closed chain knee extension, the onset of EMG activity of the four different muscle portions of the quadriceps was more simultaneous than in the open chain. In open chain, rectus femoris (RF) had the earliest EMG onset while vastus medialis obliquus was activated last (7 +/- 13 ms after RF EMG onset) and with smaller amplitude (40 +/- 30% of maximal voluntary contraction (MVC)) than in closed chain (46 +/- 43% MVC). (3)
Ask anyone "in the know" and they'll tell you that rapid and strong vastus medialis recruitment is imperative for knee health — and VMO function is the first thing to go in the presence of knee injuries. Why would we want to do an exercise that promotes delayed firing of the muscle?
And an excellent point about not over-working the rectus femoris:
Quote:
Moreover, the rectus femoris is an extremely common cause of knee and hip pain in lifters due to excessive trigger points and poor flexibility; the last thing it needs is more direct work! What it does need is lots of soft-tissue work (foam rolling, massage, ART) and dynamic and static flexibility attention.


Hey! I've been saying this for years, and keep in mind that this site, tetosterone nation is not made up of a bunch of girlie men! Seriously, at the gym, Irarely see people stretching their quads. They are usually over stretching their hamstrings, which is a muscle they hardly used.



Then , for anyone susceptible to ACL injury:



Quote:
Chow (1999) examined patellar ligament, quadriceps tendon, and patellofemoral and tibiofemoral forces at different speeds of leg extensions execution. Tibiofemoral shear forces showed that the ACL was loaded throughout the ROM — not exactly what you want (passive restraints doing the work for active restraints).


I also loved the poster's sense of humor about the research that was in favor of leg extensions. It was done on cadevers! DUH!





Quote:
Chances are that it was leg extensions that killed these people in the first place. Okay, I'm joking, but I'm more than comfortable blaming world hunger, global warming, and the situation in the Middle East on leg extensions.

Politically incorrect but hilarious!



Finally, his closing thoughts (in case anyone is too lazy to read his entire post)
Leg Extension Risks:

1. Increased patellofemoral joint reaction force, knee movement, and joint stress in the most commonly used range of motion.
2. Reduced hamstrings activity.
3. Reduced VMO activity and late onset of firing.
4. Non-existent hip adductor and abductor contribution.
5. Increased rectus femoris firing.
6. Constant ACL tension.
7. Higher patellar ligament, quadriceps tendon, and patellofemoral and tibiofemoral forces with the most commonly utilized loading parameters.
8. Increased lateral patellar deviation.
9. Insufficient involvement of surrounding joints to ensure optimal functioning.
10. Poor training economy (no carryover to closed-chain performance from open-chain exercises).

Leg Extension Benefits:

1. Will give you a good pump, but not even close to the benefits you'll get from squatting and single-leg movements.
2. Uh, wait, there's really only one benefit — and it's pretty weak.

post #2 of 21
So, Lisamarie, for someone like me who has a long history of patellofemural pain syndrome, leg extensions are a bad idea? And doing squats would be better? Is that what I'm understanding? Thanks for this article. I may need to restructure my workout!
post #3 of 21
Great post Lisamarie. I couldn't agree more!!

Here is Dan John's ten commandments of lifting (note this is only lifting and doesn't pertain to any other exercise!): http://danjohn.org/10com.html
post #4 of 21
Thread Starter 
At the risk of getting a whole lot of people very angry, I'm going to say, yes, you should defitely switch to squats! Since you are female, you already have a tenedency to have a hamstring/quad muscular imbalance, so the last thing you would want to do is an exercise that isolates an already hypertonic muscle. Good luck and let me know if you have any other questions!
post #5 of 21
Quote:
Originally Posted by Lisamarie View Post
At the risk of getting a whole lot of people very angry, I'm going to say, yes, you should defitely switch to squats! Since you are female, you already have a tenedency to have a hamstring/quad muscular imbalance, so the last thing you would want to do is an exercise that isolates an already hypertonic muscle. Good luck and let me know if you have any other questions!
Great post and thread!
post #6 of 21

squat vs leg press

i understand the problems with extensions.........but why is the squat superior to the leg press? the leg press feels safer on the back. and how much weight x reps for either? it seems to me that heavy weights x few reps doesnt make sense for an aerobic sport .we are not training for the 100 yd dash here.
post #7 of 21
Quote:
Originally Posted by duke walker View Post
i understand the problems with extensions.........but why is the squat superior to the leg press? the leg press feels safer on the back. and how much weight x reps for either? it seems to me that heavy weights x few reps doesnt make sense for an aerobic sport .we are not training for the 100 yd dash here.
Done properly, leg presses don't load the back, which makes them feel safer but also makes them useful primarily for developing your quads, not hamstrings and the rest of your posterior chain. Plus, most people don't do them properly and therefore place a lot of stress on their lumbar region.

The heavy weights vs aerobics (or anaerobic endurance) is an interesting Q with lots on it already, but without addressing the specifics either way I don't think many recreational skiers have to worry about hurting their performance by getting stronger in the gym.
post #8 of 21
Quote:
Originally Posted by duke walker View Post
it seems to me that heavy weights x few reps doesnt make sense for an aerobic sport .we are not training for the 100 yd dash here.
skiing is not an aerobic sport. while good endurance helps, more powerful skiing comes from...well, power. just like the 100-yd dash. power is a function of force over time. force comes from strength. strength comes from using heavy weights.
post #9 of 21
Thread Starter 
I like both the squat and the leg press, but I'm a maniac. However, since we ski standing up not sitting down, anything you can do standing up is helpful.

An interesting comment about squats: Our own Jeff Bergeron once came by my studio and watched me do them. He had one comment: "Do you realize that is not a skier's tuck position?" He is, of course, correct, since in a tuck, the lower back would be in a rounded position. Now, if I am teaching a ski-specific class, I perfrom one set of squats without weight, often on a piece of balance equipment. On the last rep, I have people adjust the spine into a skier tuck, and extend the legs up an inch and down an inch.
post #10 of 21
I've always thought that the leg extension machine was the worst (and most dangerous) piece of equipment in the gym.

1. For me, like I imagine a lot of people who do the ski thing, my leg muscle imbalance issue is overly strong quads vs. hamstrings. Working out on a machine that exacerbates this imbalance seemed crazy. (Much more sense to do squats, supplemented by hamstring curls, which isolate the correct muscles--hamstrings--that need more work.)

2. No functional balance component of the exercise at all.

3. Unlike squats or leg presses or lunges (or just about anything) the eccentric phase (lowering the weight) doesn't seem to mimic the eccentric muscle challenges of skiing at all, where you have to balance against an increasing load as the G forces build up in the turn. (There's a fun calculator at the following site--click on the "Biomechanical Engineering" heading most of the way down the page, which pulls up a 3 variable calclulaor--enter your skis sidecut radius (say 12 meters for slalom skis, 18 for supercross/all mountain and 21 for GS skis) inclination and angulation and it will spit out the G forces you resist in the turn along with the speed at which your inclination allows you to balance perfectly against the skis given the change in momentum)

http://www.natew.com/frame_main.cgi/...snow/html.Main

In a 60 degree inclination turn, you're resisting 2 Gs of force. In a 70 degree inclination turn you're resisting almost 3 Gs.

4. It seems to me that under heavy weights, leg extensions seem to put a lot of shearing force on the knee. I'm outside of my expertise on that area, but as a feel thing that's how it feels, and when I tore my medial collateral ligament, I was cautioned by my doctor or physical therapist (and online sources) not to do heavy weight leg extensions and to focus more on closed chain (squats) than open chain exercises.

IMHO, one reason people use the knee extension machine is that the compression of the rigid thigh while lifting gives the lifter a self image boost (My thigh is getting big! I'm pumped!) Another reason is that a lot of people are worried about back or knee problems of poor technique on squats or leg presses. For the latter concern, a session with a trainer would be money well spent, with dividends that pay off for life, with a better lower body lift forever...
post #11 of 21
I do squats, and ham curls, and leg extensions.

The last at very low weights (50-60% of ham curl capacity or 70% of body weight).

For two reasons:

Squats do not cover the range of motion that would correspond to 10 o'clock to 2 o'clock on the bicycle pedal stroke, and I refuse to have that gap.

The squat rack takes a while to set up and I want to work the opposing muscle in between ham curl sets instead of cooling off.
post #12 of 21
Do you still get bad results if your follow every set on the leg extension machine with a set on the hamstring curl machine?
post #13 of 21
FOG, from what I read above the answer looks dependent on personal physiology, how and how much you load the two machines, your form during the exercise, and could very well be 'YES'.

For my own part, I do the exercise with goals quite different than skiing, namely cycling and skating (where rectus femoris activation helps me control the set-down skate in spite of nasties in the road that want to jerk it backwards).
post #14 of 21
Quote:
Originally Posted by comprex View Post
Squats do not cover the range of motion that would correspond to 10 o'clock to 2 o'clock on the bicycle pedal stroke, and I refuse to have that gap.
I hadn't really thought of that, Comprex, (and you're certainly right that even deep squats have their practical and safety limits). For skiers that actually sounds like an excellent reason to do leg extensions, especially given that one of the biggest strength challenges in skiing is falling onto the inside ski with a deeply flexed inside leg when you lose grip on your outside ski in a high inclination turn (a sudden, inadvertent "White Pass turn" where all of your weight is on the deeply bent inside leg).

For an example, check out the picture of Daron Rahlves in the photo sequence launched under the FIS: Men's ski team link at the bottom right of:

http://www.wcsn.com/sport/index.jsp?id=34032

You'd want to have the strength to extend away from that inside foot, to be able to go somewhere other than splat.

I guess to get maximum benefit for that 10 O'Clock to 2 O'Clock pedal position, you'd have to set the leg extension machine so that the part you push was closer to your posterior at the start of the exercise than most people have the machine set.

I learn something new here all the time.
post #15 of 21
Full range of motion squats - this will get the 10 and 2 position. I thought most people have realized that squatting to only parallel argument that was made for the last 20 years or so is incorrect. Those studies were based on people with knee issues, anyone else is fine with full range of motion (done correctly of course).

If form is an issue, just use bodyweight until you get good at it.
post #16 of 21
Thread Starter 
In the end, it becomes a question of weighing the risks against the rewards. My feeling is that since there are so many different ways to work a muscle, why perform an exercise that is even remotely controversial? But then again, it becomes a matter of choice. Much of the research regarding the dangers of the leg extension machine has been suppressed, because the legal arm of the equipment manufacturers extends in many directions, and has been known to throw a few punches. The question becomes, why do the manufacturers attempt to suppress the research? If they truly believe in the safety of their product, it would be quite simple to present a counter point. Hmmmm...
post #17 of 21
Quote:
Originally Posted by Lisamarie View Post
In the end, it becomes a question of weighing the risks against the rewards. My feeling is that since there are so many different ways to work a muscle, why perform an exercise that is even remotely controversial? But then again, it becomes a matter of choice. Much of the research regarding the dangers of the leg extension machine has been suppressed, because the legal arm of the equipment manufacturers extends in many directions, and has been known to throw a few punches. The question becomes, why do the manufacturers attempt to suppress the research? If they truly believe in the safety of their product, it would be quite simple to present a counter point. Hmmmm...
The competing viewpoints may be equally valid. I don't think that the manufacturers' choice of tactic in responding to criticism of their devices tells you anything about the worth of either the criticism or other potential responses. If I were making such machines and there were ill-founded criticism, I might very well decide to ignore it in my literature and suppress it in court, if possible. There is a saying in bureaucratic circles that when you wrestle with a pig in crap, you both end up smelling like crap and the pig loves it. OTOH, if the criticism were valid, I might choose to ignore it in my literature, because it is hard to refute, and woould attempt to suppress it as best I could. Both responsees are idnetical, and you can't infer anythng from the response.

I can tell you how I am going to decide. When I work out with free weights I tend to lose accuracy, and risk direct injury. When I use a weight machine on a muscle and strengthen its antagonist on a different machine, as well as move to alternative machines which work the same general muscle groups slightly differently, I believe I have mitigated the risk the machine bears, and avoided the risk that free weights bear. Further, the machines are very convenient for exercising several muscles in rapid succession (I exercise large muscle groups first and work to small) which allows me to work out in the time available. Is it a compromise- you bet. Am I better off doing what I do rather than no program- I think so. If I were training a professional athlete would I use the same technique- not on your life.
post #18 of 21
Quote:
Originally Posted by sfdean View Post
I hadn't really thought of that, Comprex, (and you're certainly right that even deep squats have their practical and safety limits). For skiers that actually sounds like an excellent reason to do leg extensions, especially given that one of the biggest strength challenges in skiing is falling onto the inside ski with a deeply flexed inside leg when you lose grip on your outside ski in a high inclination turn (a sudden, inadvertent "White Pass turn" where all of your weight is on the deeply bent inside leg).

For an example, check out the picture of Daron Rahlves in the photo sequence launched under the FIS: Men's ski team link at the bottom right of:

http://www.wcsn.com/sport/index.jsp?id=34032

You'd want to have the strength to extend away from that inside foot, to be able to go somewhere other than splat.
Carl Jasper has found that a "deeply flexed inside knee" is vulnerable to an ACL sprain. He also found that, once your hips are below year knee, it's much safer to take the fall than to try to save yourself.
Knee extensons increase the strength of the quads, and, perhaps more importantly, train the quads to contract without a simultaneous contraction of the hamstrings. Contraction of the hamstrings unloads and protects the ACL when the knee is extended from a deeply flexed position. That s why a strength imbalance between the quads and hamstrings is another risk factor for ACL injury.
I avoid almost all gym machines. Their principal benefit is that they isolate the back out of the excercise, reducing the risk that you will sue the gym owner over a back injury. But all that really means is that you are not developing any core strength, which is far more important than leg strenth for any real skiing performance.

BK
post #19 of 21
Thread Starter 
Quote:
But all that really means is that you are not developing any core strength, which is far more important than leg strenth for any real skiing performance.
Good point!
post #20 of 21
You must consider your goals of weight training vs. rehab. Immediately following ACL reconstruction surgery regaining strength, flexibility, and muscle mass is no question the priority. The first few months require low stress on the knee and ligament in order to give it time to heal and fuse to the bone. The rule of thumb not to even break 90 degree flex in the knee for the first month says enough.
Once you are comfortable enough to shift rehabs into a workout focused on strength training for skiing (and you will know when that is once the wobbly steps disappear!), certain exercises will give specific results. I 100% believe that anyone post ACL reconstruction has no business including leg extensions in their workout. There is no need for the unecessary stress torqued on the joint. Skiing is reaction sport, and developing the fast-twitch muscle is critical to regaining/increasing balance, and power needed to pop from turn to turn. I use a workout more geared at a sprinters type of program vs. a cross country runner. Endurance is important, but the rhythm in a group of turns all begins with bounce and explosion from the legs. Free weights develop these fast twitch muscles, where machines and leg presses target a specific muscle, ie. just the quad in a leg press vs. the quad, hamstring, gluts, and all the small connecting muscle from the legs to the lower back in a squat.
Plyometrics, like the reverse lunges mentioned, and stability exerices using workout balls, wobble boards, the bosu (half a workout ball w/ flat solid bottom), lateral jumps, box jumps, etc. all promote reaction and will pay dividends in skiing performance.
I had the ACL reconstructed in my left knee in June '03, and was making my first runs of the season in late January that year, so about 7 months rehab and training. I would not consider myself 100% until a full year had passed. The first few weeks may not seem like you are accomplishing much on the road back, but are the most critical for a speedy recovery. ICE IS YOUR BEST FRIEND! I continue to wear a brace, but I think that is purely out of a additional confidence issue. No problems since, until last week, when my knee buckled (not ski related), and I am staring down a torn medial meniscus, sprained MCL, and bone contusion. Hoping to have my knee scoped before the end of the month, and I refuse to cancel my flight for a 10 day trip btw Vail and JH for the first week in Feb!!!
Rehab here we go again...
post #21 of 21
Thread Starter 
Quote:
Skiing is reaction sport, and developing the fast-twitch muscle is critical to regaining/increasing balance, and power needed to pop from turn to turn.
This is one of the things that many "equipment junkies" tend to forget. Machines are situated on a track that makes the movement responses predictable. As a result, agility and reaction times are not being enhanced. Although the initial stages of rehab may focus on strengthening the injured muscle, if you continue to perform a workout based exclusively on muscle isolation, you are training the muscles to be disfunctional, since there is not one activity in life that requuires muscle isolation.

From my own experience, my PT went nowhere until I ignored my doctors orders and started teaching again. The muscle isolation exercises were not doing a thing for me.
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