Here a few of the most interesting key points:
|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!|
Then there's this:
|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?
|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:
|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!
|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:
Leg Extension Benefits:
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).
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.