Muscle Action in the Squat

[Guest guest]

Dr - Is this because of the " all or none principle " that

there is no significant change in the pressures

exerted on various muscles ? How does the " all or none

principle " figure in this conclusion.

[The all-or-none principle applies to the activity of muscle units at

a cellular level not to the summated action of large groups of gross muscles at

a global level. According to the all-or-none principle, a muscle

unti is either " on " or " off " , " at rest " or fully discharging - it is a

case of all or nothing happening. At the gross level of large muscle groups,

tension in the muscle is created by the synergistic action of huge numbers

of contributing muscle units and the case never happens that all of these

units are at rest or all fully activated in a given motor action. It is

due to neuromuscular programs being used in the nervous systems of the body

that our muscles contribute in different patterns and to different degrees

in every movement. Mel Siff]

Prasad Rangnekar

Mumbai India

------

Dr Mel Siff wrote:

> This research article analyses muscle involvement in

> the powerlifting squat.

>

> Med Sci Sports Exerc 1999 Mar;31(3):428-36

>

> Stance width and bar load effects on leg muscle

> activity during the parallel

> squat.

>

> McCaw ST, Melrose DR.

>

> PURPOSE: Altering foot stance is often prescribed as

> a method of isolating

> muscles during the parallel squat. The purpose of

> this study was to compare

> activity in six muscles crossing the hip and/or knee

> joints when the parallel

> squat is performed with different stances and bar

> loads.

>

> METHODS: Nine male lifters served as subjects.

> Within 7 d of determining IRM

> on the squat with shoulder width stance, surface EMG

> data were collected (800

> Hz) from the rectus femoris, vastus medialis,

> vastus lateralis, adductor

> longus, gluteus maximus, and biceps femoris while

> subjects completed five

> nonconsecutive reps of the squat using shoulder

> width, narrow (75% shoulder

> width), and wide (140% shoulder width) stances with

> low and high loads (60%

> and 75% 1RM, respectively). Rep time was controlled.

> A goniometer on the

> right knee was used to identify descent and ascent

> phases. Integrated EMG

> values were calculated for each muscle during

> phases of each rep, and the

> 5-rep means for each subject were used in a repeated

> measures ANOVA (phase x

> load x stance, alpha = 0.05).

>

> RESULTS: For rectus femoris, vastus medialis, and

> vastus lateralis, only the

> load effect was significant. Adductor longus

> exhibited a stance by phase

> interaction and a load effect. Gluteus maximus

> exhibited a load by stance

> interaction and a phase effect. Biceps femoris

> activity was highest during

> the ascent phase.

>

> CONCLUSION: The results suggest that stance width

> does not cause isolation

> within the quadriceps but does influence muscle

> activity on the medial thigh

> and buttocks.

>

> --------------

>

> Dr Mel C Siff

[Guest guest]

For the squat, any, or lunge:

Have the relationships between foot distribution forces( e.g. heel-ball

weight distribution), heel elevation/declination, ankle, knee, hip and back

angles, and resistance load and placements in conjunction with EMG readings

been attempted ?

[Yes, this has been done for the squat as part of the Olympic lifts, but most

of them have been carried out without concurrent EMG measurement. Many years

ago Dr Grahammer published a few articles on locus of loading for foot

contact in the Olympic lifts. Popularised versions appeared in the

International

Olympic Lifter published by Bob Hise. My mech eng students also did some

projects on that topic for me, using myotonometry rather than EMG, but the

project

reports are still sitting in storage among all the materials that I could not

bring with

me when I moved from SA. As you imply, there surely should be many such studies

in this field. Mel Siff]

With todays tech it doesnt seem that big of a hurdle.

Jerry Telle

lakewood Colorado USA

jrtelle@...

[Guest guest]

There was an interesting article recently posted on the coaches information

service web site with some excellent fiqures on this issue.

http://www.education.ed.ac.uk/strength/papers/ms3a.html

The Use of Weightlifting Pulling Movements in Sport

- Introduction /Snatch Versus The Clean

Mike Stone & Gattone USOC Sport Science & Coaching, USA

Margaret Stone ish Institute of Sport

Schilling Memphis University, USA

Pierce & Byrd USA Weightlifting Development Center,

LSU-Shreveport

There are multiple links for the article on:

• Introduction / Snatch Versus The Clean

• Common Pulling Errors

• Importance of the Double Knee Bend Phase / Importance of Using

Weightlifting

• Movements in Sports Training

• Movement Pattern Specificity / Advantages of Using Pulling Movements

• Weightlifting Training / Summary

Tom Green, CSCS

St. Louis, MO

>From: JRTELLE@...

>Reply-To: Supertraining

>To: Supertraining

>Subject: Re: Muscle Action in the Squat

>Date: Sat, 3 Aug 2002 16:40:14 EDT

>

>For the squat, any, or lunge:

>

>Have the relationships between foot distribution forces( e.g. heel-ball

>weight distribution), heel elevation/declination, ankle, knee, hip and back

>angles, and resistance load and placements in conjunction with EMG

>readings

>been attempted ?

>

>[Yes, this has been done for the squat as part of the Olympic lifts, but

>most

>of them have been carried out without concurrent EMG measurement. Many

>years

>ago Dr Grahammer published a few articles on locus of loading for foot

>contact in the Olympic lifts. Popularised versions appeared in the

>International

>Olympic Lifter published by Bob Hise. My mech eng students also did some

>projects on that topic for me, using myotonometry rather than EMG, but the

>project

>reports are still sitting in storage among all the materials that I could

>not bring with

>me when I moved from SA. As you imply, there surely should be many such

>studies

>in this field. Mel Siff]

>

>With todays tech it doesnt seem that big of a hurdle.

>

>Jerry Telle

>lakewood Colorado USA

>jrtelle@...

>

_________________________________________________________________

Chat with friends online, try MSN Messenger: http://messenger.msn.com

[Guest guest]

---

Hi Jerry!

Some of the best biomechanical work on squat, leg press, and deadlift

variations has been done by Dr. Escamilla, of Duke University.

They appeared in the issues of Med. Sci. Sports & Exerc. in 2001 and

2002 and in the Journal of Strength & Conditioning research during the

same time period. Dr. Glen Fleisig, Alabama Sports Medicine

Institute, did some fine work on the same topics that appeared in the

American Journal of Sports Medicine in the late '90's.

Best Wishes!

Dan Wathen, Youngstown (OH) State University

In Supertraining@y..., JRTELLE@A... wrote:

> For the squat, any, or lunge:

>

> Have the relationships between foot distribution forces( e.g.

heel-ball

> weight distribution), heel elevation/declination, ankle, knee, hip

and back

> angles, and resistance load and placements in conjunction with EMG

readings

> been attempted ?

>

> [Yes, this has been done for the squat as part of the Olympic lifts,

but most

> of them have been carried out without concurrent EMG measurement.

Many years

> ago Dr Grahammer published a few articles on locus of loading

for foot

> contact in the Olympic lifts. Popularised versions appeared in the

International

> Olympic Lifter published by Bob Hise. My mech eng students also did

some

> projects on that topic for me, using myotonometry rather than EMG,

but the project

> reports are still sitting in storage among all the materials that I

could not bring with

> me when I moved from SA. As you imply, there surely should be many

such studies

> in this field. Mel Siff]

>

> With todays tech it doesnt seem that big of a hurdle.

>

> Jerry Telle

> lakewood Colorado USA

> jrtelle@A...

[Guest guest]

Jerry Telle:

<And finally has anyone measured/estimated the contribution of the

gluteus maximus deep fibers (not ITB band fibers) in hip extension--all the

anatomy books I have skirted the issue.>

Flanagan:

**Jerre, do you mean inferior fibers? I didn't think the glute max was

divided into deep and superficial fibers.

Flanagan >>

Hi ,

One book I have " Anatomy of Movement " by Calais-Germain. Eastland Press 1993

pg 228 uses " deep " and " superficial " though I like and imagine yours is the

more accurate. Another, " Illustrated Essentials of Muscoloskeletal Anatomy " ,

Sieg and , pg 86 doesnt use any terminology !! Little wonder there's

confusion.

Oh, and yes

cheers,

Jerry Telle

Lakewood Colorado USA

jrtelle@...