Pelvic stabilization exercise versus conventional weight training exercise during resistance training: Its effect on the development of lumbar extension strength

Mark Allen Belcher


The purpose of this study was to compare the difference of strengthening the lumbar spine using the MedX Lumbar Extension Machine and performing a dead lift exercise using free-weights. Subjects were randomly assigned to 8 weeks of dynamic strength training utilizing the MedX (n = 23), performing the dead lift exercise (n = 22), or a non-exercising Control group (n = 10). Results indicated that there was no significant difference in strength gains between the treatment groups and no significant strength change in the Control group. There was, however, a significant interaction among the treatment groups for test-day by angle by group. This interaction possibly revealed a beginning strength improvement within the MedX group and a plateauing of strength within the Free-Weight group. The improvements seem to yield credence to two thoughts: (1) that it takes at least 8 weeks for significant increases in muscle strength to begin, and (2) that isolation of a muscle group appears to yield greater strength than neurologic overflow from synergistic muscles.