Skeletal-Site Specific Effects of Endurance Running on Bone Structure and Strength in Growing Rats
Bibliographic record
Abstract
High impact activities, such as running, induce positive effects on bone mass and bone strength. However, there are discrepancies in the magnitude of changes due to exercise, mainly as a result of varying training protocols (i.e. duration, intensity, and mode), analysis techniques, and bone sites being measured (weight bearing vs. non-weight bearing sites within a bone). PURPOSE: To determine the effect of endurance running on structure and strength of weight bearing (tibia) and non-weight bearing (lumbar vertebra and mandible) bones in growing male rats. METHODS: 8-week-old male Sprague-Dawley rats were randomly assigned to either the trained (n = 9) or control group (n = 10). Rats in the trained group underwent a progressive treadmill running program for 8 weeks (25 m/min for 1 hour, incline of 10%). Microcomputed tomography was used to measure bone structure and strength of tibia, lumbar vertebra and mandible at a resolution of 9 um. Outcomes included bone volume fraction, BV/TV; trabecular number, Tb.N; trabecular thickness, Tb.Th; trabecular separation, Tb.Sp. RESULTS: At the proximal tibia, training resulted in higher BV/TV (23.77 ± 1.06 vs. 20.95 ± 0.91%, p = .03), Tb.N (2.53 ± 0.11 vs. 2.18 ± 0.09 mm-1, p = .01) and lower Tb.Sp (0.26 ± 0.015 vs. 0.32 ± 0.02 mm, p = .05) compared to control rats. No significant differences at the tibia midpoint or lumbar vertebra were found. At the mandible, trained rats had lower BV/TV (63.00 ± 1.57 vs. 69.13 ± 1.45%, p = .01), Tb.Th (0.22 ± 0.01 vs. 0.26 ± 0.01 mm, p = .0002), Tb.N (2.66 ± 0.03 vs. 2.81 ± 0.06 mm-1, p = .02) compared to control rats. This effect may be due to a lower amount of mechanical force due to chewing, as control rats had a significantly higher weekly food intake (471.20 ± 2.82g vs. 384.30 ± 3.53 g/cage/week, p < .0001). CONCLUSION: Endurance running in growing male rats results in site-specific effects to the skeleton. Bone structure is improved by direct loading (tibia) while lumbar vertebra, a bone that is not loaded is unchanged, and mandible structure was compromised due to less loading resulting from a lower food intake induced by the endurance training protocol. Supported by NSERC Discovery Grant 229767.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".