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Muscular Contribution to Low Back Loading and Stiffness

During Standard and Suspended Push Ups

Tyson A.C. Beach, Samuel J. Howarth, Jack P. Callaghan

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INTRODUCTION

! 

Why are push-up exercises performed? Increase strength or

endurance of muscles that span the upper extremity joints

! 

Trunk muscle activation: labile vs. stable surfaces

! 

Muscle sti

 

ness and joint sti

 

ness

! 

Why this study?

! 

To examine whether di

 

erences exist in trunk muscle activation levels 

contributions to lumbar IVJ loading androtational sti

 

ness when standard

push-ups were compared to suspended push-ups

 

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METHODS

! 

11 trained male volunteers

! 

1 set suspended 1 set standard

push-ups (8-10 repetitions)

! 

IRED’s andEMG recording

electrodes used to assess

muscle activation

! 

Contribution of all spanning

muscles about each axis of each

IVJ were summed and averaged

 

1.83m9.4kg

AGE: 27.4

Standard Push-Up

 

Suspended Push-Up

 

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RESULTS

! 

Muscles of the abdominal wall andlatissimus dorsi had increased

mean and peak muscle activation during suspended push-ups

! 

As a direct result of increased muscle activation levels, lumbar

L4/L5 compressive forces and lumbar intervertebral joint 

rotational sti

 

ness were also significantly greater

! 

No significant di

 

erences in linked-segment model outputs or lumbar spine posture

 

0

10

20

30

40

50

60

RECTUS

ABDOMINIS

EXTERNAL

OBLIQUES

INTERNAL

OBLIQUES

LATISSIMUS

DORSI

     %     o

     f     M     V     I     C

STANDARD SUSPENDED

Copyright © 2009 Pearson Education Inc.

 

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DISCUSSION

! 

Due to the instability of a labile surface, the abdominal muscles illicit

hoop stresses to increase stability in the lower spine

! 

Abdominal activation during push-up can approach or exceed

magnitudes recorded during more conventional abdominal

exercises

! 

Prescribe push-ups as a form of abdominal exercise

! 

Lower back compression with no deviation from neutral

! 

No participant experienced L4/L5 IVJ shear loads in excess of 1 kN

! 

Suspended push-ups may increase the risk of low-back injury for

some individuals

! 

Compressive loads exceeded 3.4 kN limit set by NIOSH

!  Study is based on outputs of a biomechanical model

! 

Sensitive to di

 

erences in anatomical parameters

! 

This model was constructed based on male-based data set

 

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CONCLUSION

! 

Push-up exercise presents an abdominal muscle challenge

! 

More pronounced when the hands were interfaced with a labile support

surface

!  Compared to standard push-ups, suspended push-ups provide a

superior abdominal muscle challenge based on measured

activation levels and lumbar IVJrotational sti ness

! 

For individuals unable to tolerate large magnitude low-back

compressive loads, benefits gained by incorporating suspended

push-ups may be outweighed by the potential risk of overloading

low-back tissues

! 

Future studies examining upper extremity biomechanics while

performing push-ups on labile support surfaces to provide a more

complete justification for their use in resistance training programs