This study aimed to extend the work of previous studies by investigating the effects of lumbar extension training beyond 12 weeks. Specifically, this study intended to determine how a longer training period would affect lumbar extension torque using varied training frequencies and to determine whether a longer training period would affect the shape of the isometric lumbar extension torque angle curve. Potential benefits associated with continued training would aid therapists in designing appropriate treatment programs.
56 subjects were randomly assigned to three training groups: group 1 trained once every other week, group 2 trained once per week, group 3 trained twice per week, and a control group did not train. All subjects were given a test prior to and following 12 and 20 weeks of training that evaluated isolated isometric lumbar extension torque in a seated position at seven positions through a 72 degree range of motion. All training groups showed significant increases in lumbar extension torque at both 12 and 20 weeks of training; the control groups showed no change in isometric torque. Greater increases in isometric torque at the fully extended position then at the fully flexed position at 12 weeks and at 20 weeks caused the shape of the isometric torque-angle curve to change as a result of training. The findings of this study show that isometric lumbar extension torque increases occur mainly within the first 12 weeks of training, although additional gains in the more extended positions can be expected when training is continued through 20 weeks. Also, this data indicates that training once every other week or once per week is as effective as training twice per week or three times per week for increasing isometric lumbar extension torque over 20 weeks.
- Training groups showed a significant increase in isometric torque at all angles at 12 and 20 weeks while the control group showed no change
- Significant time x angle interaction at 12 weeks indicating the shape of the torque angle curve changed as a result of the training
- Relative changes in isometric torque for the combined group ranged from 16.4% at full flexion to 91.9% at full extension
- 20 week values revealed that on average the training groups continued to show an increase in isometric torque at 5 of the 7 angles
- Combined group data showed an additional 31% improvement at the fully extended position at 20 weeks
Keywords: Lumbar, MedX Lumbar Extension Machine, training periods, isometric torque, lumbar extension, 12 weeks, 20 weeks