CrossFit Discussion Board  

Go Back   CrossFit Discussion Board > CrossFit Forum > Exercises
CrossFit Home Forum Site Rules CrossFit FAQ Search Today's Posts Mark Forums Read

Exercises Movements, technique & proper execution

Reply
 
Thread Tools
Old 07-18-2007, 11:11 PM   #1
Wayne Nelson
Member Wayne Nelson is offline
 
Profile:
Join Date: Apr 2007
Location: Roseville/Crockett  California
Posts: 114
The advice on the Main Page in the post on sit ups with its link to the article by Koch, Blom, and Jacob fails to reflect current scientific evidence or follow recommendations made in today's literature for core training.

The key function of the abdominals is for core/spinal stabilization. The key function of the rectus abdominus is trunk flexion. EMG studies have demonstrated that regional activation of the rectus abdominus is impossible, that the muscle cannot contract regionally.

EMG Studies have demonstrated that the psoas only activates when there is hip flexion and very minimally involved during the sit-up if there is no hip movement.

Spinal disc compression during the sit up exceeds NIOSH's minimum limit for repetitive loading. This level does not include repetitive flexion affects or shear forces that occur concurrent with each repetition during the sit up. Flexion of the lumbar disc has been demonstrated to the primary cause of lumbar disc herniation. When forward bending is performed in a neutral spine this risk is essentially eliminated. When compression to the lumbar spine occurs in neutral or extension failure occurs at the vertebral endplates, not the disc.

My final comment concerns the function of the abdominal musculature: stabilization and endurance. Curl ups, as dangerous as they are to the lumbar spine, do little to improve the function of the core muscles. Without a properly balance program curl ups create a flexion imbalance of the core muscles dominating core balance and overpowering the extensors. A loss of extensor endurance relative to flexor endurance has been demonstrated to correlate with and result from low back pain and injury.

There are plenty of exercises for core training that target the core more appropriately and provide a margin of safety that far exceeds the curl up. Given the current evidence one should only give academic interest to this article and should follow sound evidence when designing an appropriate core-training program.

For references see “Core 1” attachment under a previous post.
  Reply With Quote
Old 07-19-2007, 02:41 AM   #2
Thomas Grippo
Member Thomas Grippo is offline
 
Profile:
Join Date: Oct 2006
Location: Basking Ridge  NJ
Posts: 44
I like Siff's rant:

*role: stabilize/mobilize
*straight leg sit-up - avoid hip flexion
*Eastern Nations take
*train them for strength like any other muscle
  Reply With Quote
Old 07-19-2007, 08:44 AM   #3
Wayne Nelson
Member Wayne Nelson is offline
 
Profile:
Join Date: Apr 2007
Location: Roseville/Crockett  California
Posts: 114
"train them for strength like any other muscle"

Taken from a bodybuilding site, it even sounds like a bodybuilding approach! As I understand it, CF focuses on training to improve functional performance.
  Reply With Quote
Old 07-19-2007, 09:03 AM   #4
Lincoln Brigham
Member Lincoln Brigham is offline
 
Lincoln Brigham's Avatar
 
Profile:
Join Date: May 2003
Location: Kirkland  WA
Posts: 3,987
The NIOSH is in charge of monitoring industrial accidents. Accidents are the primary cause of disc herniation, not situps. As far as I know the NIOSH has never trained a single person for fitness. They are not experts in the field of fitness, not by any stretch of the imagination.

Crossfit incorporates a TON of extensor exercises in addition to flexion. In fact, if anything the Crossfit WODs favor posterior chain exercises. I'm surprised you haven't noticed that.
  Reply With Quote
Old 07-19-2007, 09:14 AM   #5
Gerhard Lavin
Member Gerhard Lavin is offline
 
Profile:
Join Date: Jun 2005
Location: Berlin  Germany
Posts: 973
The heavy and fast lifts combined with L sits, knees to elbows and situps will give you all the core strength you need. Though in some planks and isometric stuff if you feel like it as well

The same lifts give plenty of work to the hip extensors and the whole posterior chain

Plus "train them for strength like any other muscle" isn't a bodybuilding approach. For BB strength is a tool, appearance is the goal.

  Reply With Quote
Old 07-19-2007, 09:47 AM   #6
Corey Duvall
Member Corey Duvall is offline
 
Profile:
Join Date: Mar 2007
Location: Asheville  NC
Posts: 340
I was coming onto this board to post comments very similar to Wayne's. The function of the trunk flexors and the trunk extensors is for maintaining a neutral spine. Our trunk is designed to allow transfer of power from the lower extremity to the upper extremity and it does so most effectively by maintaining an isometric contraction giving a rigid core with mobile extremities. I have found that the GHD situps and hip extensions to be EXTREMELY effective in giving strength and mobility to the hip joints while maintaining a neutral spine. These should be performed not by flexing and extending the spine but by keeping it neutral and flexing/extending the hips.

I feel the uncertainty comes about when you look at isolated muscles and attempt to train them. This, from what I have gathered, is not what Crossfit endorses. They endorse function, and as such trunk stability is a function while maximal rectus abdominis concentric contraction is not. Sure, full trunk flexion produces the shortest distance of origin/insertion for rectus but that is not the function of the muscle. It is to balance the extensors in maintaining a neutral lumbar spine. One more point is that training muscles for "strength" must also take into account the nervous innervation as well. Strength should be defined as the ability to control a mass, not how much mass is moved. The body works with motor recruitment patterns, and teaching the trunk extensors/flexors to mobilize the spine is not improving strength as it does not allow the body to control the spine properly.

I am more than willing to here disagreements or otherwise.
  Reply With Quote
Old 07-19-2007, 10:37 AM   #7
Lincoln Brigham
Member Lincoln Brigham is offline
 
Lincoln Brigham's Avatar
 
Profile:
Join Date: May 2003
Location: Kirkland  WA
Posts: 3,987
So is the situp necessary? Per Ger and Corey, no. The advice on the main page describes the situp as "complementary" to the GHD. But if you are going to do situps anyway, is the Abmat approach the best way? I'd say yes. Is it unsafe? I think Wayne is reading too much into the wrong data. It's hearsay science*. I doubt the NIOSH has ever directly tested the safety of the Abmat situp. And it's not their job to do so, not their area of expertice.

*The NIOSH finds a correlation between back pain and spinal compression forces above 3,300 newtons. (Among sedentary workers, we assume.) Then Stuart McGill tests the standard bent-knee situp and finds compressive forces of 3,350 newtons. From this Wayne draws the conclusion that Abmat situps with knees apart are scientifically shown to be dangerous for active individuals. Do you see how this becomes a game of "Telephone"?

(Message edited by lincoln on July 19, 2007)
  Reply With Quote
Old 07-19-2007, 11:16 AM   #8
Daniel Schmieding
Member Daniel Schmieding is offline
 
Daniel Schmieding's Avatar
 
Profile:
Join Date: Apr 2004
Location: Petaluma  Ca
Posts: 261
sure I'm not going to have an AbMat if I get stuck in a situation where I need to utilize my hip/stomach muscles and SitUp.

Beyond that, training the abs "for strength like any other muscle," sounds good to me. That was no a bodybuilding-esque comment, as training for strength will not always lead to the greatest size development. I'd much rather be able to sit up while somebody is holding my legs as I dangle off a cliff than to be able to do a whole bunch of proper situps. Hopefully I can have both.

  Reply With Quote
Old 07-19-2007, 08:00 PM   #9
Bill Russell
Affiliate Bill Russell is offline
 
Bill Russell's Avatar
 
Profile:
Join Date: May 2006
Location: Cleveland  OH
Posts: 503
Add some Parkour training if you really want to light up your abs!

I had an hour workout with Jesse Woody last winter that hit my midline harder than anything I had done in years.
  Reply With Quote
Old 07-19-2007, 11:14 PM   #10
Wayne Nelson
Member Wayne Nelson is offline
 
Profile:
Join Date: Apr 2007
Location: Roseville/Crockett  California
Posts: 114
Lincoln: So, is there something I missed about the differences in disc anatomy and physiology between the sedentary worker and the CF athlete? From what I have read, there doesn’t seem to appear to be any differentiation between occupations. Help me out here. Research that has come my way has demonstrated that disc injuries result from compression during flexion. Disc failure occurs only during flexion, not extension. And, the situation is compounded when including anterior shear and translational forces.

Actually the NIOSH correlation to repetitive loading rates over 3300 N is to higher rates of injury in workers. (Hmm, repetitive doesn’t sound too sedentary.) Keep in mind this limit is repetitive loading and does not figure in anterior shear from some flexion activities. Flexion is important because the interspinous ligaments and erector spinae are unable to counter anterior shear at full flexion. In fact these elements contribute to anterior shear as the resultant fiber realignment at full flexion.

If you read on in McGill you will find him saying:
“… The issue is not which type of sit-up should be recommended. Rather sit-ups should not be performed at all by most people. Far better ways exist to preserve the abdominal muscle challenge while imposing lower spine loads. Those who are training for health never need to perform a sit-up; those training for performance may get better results by judiciously incorporating them into their routine.” (There is no mention of what “judicious” means in terms of reps and sets)

Given the research, there seems to be some compelling evidence against sit-ups and in favor of other exercises that produce less spinal loads. Given all the alternatives to the sit-up there is no need to perform that exercise.

Corey has made some very relevant remarks as to the function of the core. As has been said before on this board, functional training reinforces movement patterns that reinforce efficient and correct function. The core is the transfer box to the power developed in the upper and lower extremities. If the core is sloppy, it absorbs energy and optimum power transfer is compromised. The answer to this is to train the core to minimize movement when power demands are high. This will minimize overload on the core and maximize power transfer. The muscles of the core and trunk cannot compare to the muscles of the upper and lower extremities on their potential to generate force. Furthermore, the physiology and anatomical leverage of core muscles are different than the phasic muscles of the extremities. This describes a different function. (Wolf’s Law: Function determines structure)
  Reply With Quote
Reply


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Abmat Vs Other Back Support Allan Talusan Equipment 4 07-19-2006 07:46 PM
Abmat situps or GHD Joseph Hart Exercises 3 03-16-2006 11:40 AM
Abmat as a back rest Bryant Powers Equipment 1 10-08-2005 12:48 PM
AbMat Skip Chase Equipment 6 09-21-2005 10:47 AM
Abmat for situps? Russ Thornton Equipment 21 06-14-2005 06:20 PM


All times are GMT -7. The time now is 06:16 PM.


CrossFit is a registered trademark of CrossFit Inc.