Date of Award

4-2022

Degree Type

Thesis

Degree Name

Master of Science

Department

Health and Human Performance

Program

Exercise Science

First Advisor/Chairperson

Dr. Randall Jensen

Abstract

Increasing intra-abdominal pressure (IAP) during free weight exercises can protect the lumbar spine from excess movement; a cause of lower back pain. Abdominal bracing (AB) and abdominal hollowing (AH) are two stabilizing maneuvers that increase IAP. Previous literature primarily compared AH and AB in therapy settings on bodyweight single joint movements. The effect of AB and AH during a multi-joint movement involving a maximum or near maximum external load is unknown. The purpose of this study was to compare the effect of AB and AH on lower limb muscle activity and the maximum amount of external weight lifted during a 1RM back squat protocol. Mean-normalized surface electromyography of the rectus femoris, biceps femoris, gluteus maximus, rectus abdominis, external oblique and erector spinae were analyzed in well trained individuals (n=13). A 1RM back squat protocol was performed under three conditions: control session, AB and AH. A significant difference was found between maximum external load lifted during both AB (124.39kg ± 8.77) and AH (123.46kg ± 8.84) conditions compared to the control day (120.53kg ± 8.71). No significant differences for the muscle activity were found under the conditions at the same weight, however, analyzing the max weight at every condition showed a significant difference of BF during AH (p=0.04). In summary, abdominal stabilizing maneuvers, AB and AH, increases 1RM back squat weight. As the increase in weight lifted cannot be accounted for by an increase in prime mover muscle activity, more research is needed to establish what caused the increase.

Access Type

Open Access

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