Date of Award


Publication Type

Master Thesis

Degree Name




First Advisor

Potvin, J. R.,


Health Sciences, Rehabilitation and Therapy.



Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.


This purpose of the study was to investigate the effects of fatigue on the response of the trunk to a variety of conditions of initial static loads and step inputed loads causing rapid sagittal trunk flexion. The variables measured in the study were the pre-trial and peak EMG levels from 5 bilateral trunk muscles, peak extensor moments, peak trunk flexion angle, trial duration, time to peak moment and times to peak EMG levels. The findings provide evidence that there were some changes in the response of the spine to sudden loading during fatigue conditions. However, the only main effect of fatigue was for the TES response to the different added loads. There was also a significant interaction between fatigue level and pre-load for the maximum trunk flexion variable, with the fatigued 4% pre-load trials having greater values than the rested 4% pre-load trials. The expected increase in LES and trunk flexor (co-contraction) EMG activity during fatigue was not observed. A review of the individual subject data revealed that two subjects did demonstrate increases in agonist and antagonist muscle activity for the fatigued loading conditions, when compared to the rested conditions, and one subject was observed to have increased peak flexion values as a result of fatigue. Overall, the data seem to indicate that fatigue affects individuals in different ways, with respect to spine mechanics. It may be hypothesized that some subjects were more susceptible to the effects of fatigue. This may help explain why some, but not all, individuals are injured while manual material handling over prolonged periods. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2000 .P36. Source: Masters Abstracts International, Volume: 40-03, page: 0698. Adviser: J. R. Potvin. Thesis (M.H.K.)--University of Windsor (Canada), 2000.