Powerlifting Bench Press

The Effectiveness of Weight-belts During the Squat Exercise

Lander et al (1) examined the effects of  the use of weight belts on spinal compression and muscle  activity during the squat exercise.  Six experienced  male trainees were examined;  all subjects could  squat 1.5 to 2.38 times their body weight in a squat  exercise.  Three conditions were examined:  no  weight belts, a light weight belt 7 mm thick and 10 mm  wide in the center, and a heavy belt 11 mm thick and 100  mm wide along the entire belt.  The experimenters  also examined three loading conditions:  70%, 80%,  and 90% 1 RM.  All performances were filmed and  digitized.  Vertical, anteroposterior, and  mediolateral forces were measured using a Kistler force  platform.  Intra-abdominal pressure (IAP) was  measured using a ballloon catheter inserted in each  subject's rectum.  EMG signals from the rectus  abdominus, the external obliques, and the erector spinae  were measured.

Kinematic data was generated from the  digitized film.  The lift was divided into 6 phases;   the downward phase of the squat was P1-P3, and the  upward phase was P4-P6.  Joint moments were  calculated using data from the force platform and from  position data from the digitized film.  Forces  acting upon the spine were also calculated.

FINDINGS:  The most significant  differences between trials were found when using weights  at 90% 1 RM, so the authors only presented the results of  this condition.  When using a weight belt, the  anteroposterior center of pressure was located farther  forward than when not using a weight belt.  IAP was  highest during P4 (P4 was the initial upward movement as  soon as the bottom position was reached) and was also  highest when using a weight belt.  Maximum values  for joint moments occurred during P4;  joint moment  data also suggested that subjects using a weight belt  relied more upon the trunk muscles to raise the weight  than individuals not using a weight belt, since knee  moments were higher when individuals did not use a belt.   Spinal compression was highest during P4, and was 2.8-6.2%  lower in the weight belt conditions as compared to no  weight belt.  Mean back muscle forces were 2.6-5.0%  greater without a weight belt.  mEMG values for the  no weight belt condition were greater than the two weight  belt conditions (8.3-23.5% greater for the rectus  abdominus, 13.4-44.2% greater for the external oblique,  and 11.6-22.9% greater for the erector spinae).

IMPLICATIONS:  The increase in IAP  provided by a weight belt may help prevent injury by  reducing compression forces acting upon the spine and  reducing back muscle forces.  However, muscle  activity of the trunk appears to be significantly reduced  when using a weight belt, so the trunk may not receive as  good of a training stimulus as it would if no belt was  worn.  Since the authors found the most significant  differences during the heaviest trial, it may be prudent  to not wear a weight belt during lighter sets to that the  trunk musculature may receive a training stimulus.  A  weight belt can then be worn for heavier sets (>80% 1  RM) to help increase IAP and reduce spinal compression  forces.  More research is warranted on what would be  optimal times to use a belt and what would not.

1.  Lander, J.E., R.L. Simonton, and  J.K.F. Giacobbe.  The effectiveness of weight-belts  during the squat exercise.  Med. Sci. Sports  Exerc.  22(1):117-126.  1990.