Purpose: This investigation evaluated the effects of a high-load (50% body weight) eccentric exercise training protocol on reloading myofibrillar damage in soleus (SOL) and extensor digitorum longus (EDL) muscles in rats following 7 days (d) of hindlimb suspension unloading (HSU). Methods: 48 female Sprague-Dawley rats were randomly stratified to four experimental groups; exercise + hindlimb suspension unloading (ExHSU), hindlimb suspension unloading (HSU), exercise (Ex) and control (C). The ExHSU and Ex groups underwent a high-load eccentric exercise protocol for ~2.5 weeks. Following exercise training, the ExHSU and HSU groups underwent 7 d of hindlimb suspension unloading and a subsequent 16-19 h reloading period. ANOVA was used to determine significance between groups for the following variables: body weight (BW) across time, BW at sacrifice, Glucose-6-phosphate dehydrogenase (G-6-PDH) activity, fiber area, fiber area to body-weight ratio, % myofibrillar damage, SOL and EDL wet, dry and wet-weight to body-weight ratios, % interstitial area, adrenal weights and adrenal weight to body-weight ratios, tibia lengths and tibia bone mineral content. Results: ANOVA revealed no significant differences (p > .10) between the ExHSU and HSU groups for BW at sacrifice, fiber area, fiber area to body-weight ratio, SOL and EDL wet, dry and wet-weight to body-weight ratios, adrenal weights and adrenal weight to body-weight ratios and tibia lengths and bone mineral content. Yet a post analysis t-test revealed a significantly higher % of myofibrillar damage in the HSU vs. the ExHSU group. Further, G-6-PDH activity and % interstitial area approached significance (p = 0.134 and p = 0.152, respectively). Conclusions: The high-load eccentric exercise training protocol prior to HSU attenuated the % of myofibrillar damage during reloading. Further, the % of interstitial area and G-6-PDH activity tended to be smaller in the ExHSU group vs. the HSU group. Therefore, eccentric exercise prior to HSU may elicit a repeated bout effect and attenuate the amount damage incurred by the muscle during reloading. Additionally, this investigation was the first to demonstrate increased G-6-PDH activity with reloading myofibrillar damage.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-0711102-184930 |
| Date | 12 July 2002 |
| Creators | Prisby, Rhonda Dianne |
| Contributors | Arnold Nelson, Changaram Venugopal, Robert Wood, Maren Hegsted, Mike Keenan |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-0711102-184930/ |
| Rights | unrestricted, I hereby grant to LSU or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University Libraries in all forms of media, now or hereafter known. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. |
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