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Effect of Resistance Training on Lumbar Extension Torque Production


    Utilizing the lumbar extension machine is shown to alleviate discomfort in the lower back. This study is from a physical therapy research paper which examines the impact of isometric lumbar extension torque across 12 and 20-week periods. The data suggests that performing one set of 8 to 12 variable-resistance lumbar extensions until fatigue, either bi-weekly or weekly, leads to increased strength in lumbar extension.


    The study, “Effect of 12 & 20 Weeks of Resistance Training on Lumbar Extension Torque Production” examines the impact of a 12 or 20-week training period testing isometric lumbar extension torque. 56 participants were randomly assigned to train once every other week, (training group 1, n=10), once per week (training group 2, n=12), twice per week Training group 3, n=12), or three times per week (training group 4, n=7) or at a non-training control group (n=15).

    The study involved subjects performing a single set of 8 to 12 variable-resistance lumbar extensions until they reached muscle fatigue. Before and after 12 and 20 weeks of training, subjects underwent a test assessing their isolated isometric lumbar extension torque while seated at seven different positions spanning a 72-degree range of motion. The participants’ age, height and weight (ANOVA) were analyzed to see if those attributes determined differences in the study.  Isometric torque was measured in foot pounds and then converted to newton meters. The changes in the isometric torque were analyzed as well as the different training weights used.

    This study builds on previous research which found consistent lumbar extension torque improvements across different training frequencies over a 12-week span. Even extending the training period by eight weeks did not change these findings. There were consistent torque gains observed from week 12 to 20, especially in terms of range of motion. These results highlight the importance of pelvic stabilization and multi-angle testing for precise strength assessment.