Bone and Muscle Relations in Elite Adolescent Male Cross-Country Skiers
Bibliographic record
Abstract
1079 Exercise associated muscle induced bone strain has potential osteogenic effects that may increase skeletal density, bone cross-sectional area and structural strength. Whether the effects of exercise and the muscle-bone relation are similar in weight bearing and non-weight bearing bones remains to be determined. PURPOSE: This study compared bone density, as well as bone and muscle cross-sectional areas of 13 adolescent male cross-country skiers competing at the Provincial and National levels with published age and maturity matched normative data (ND) on healthy non-athletic males. METHODS: Skiers were 17.3 +/− 1.1 years old, 177.4 +/−4.4 cm tall, 70.2 +/− 8.25 kg, 12.4+/−4.3% body fat, and Tanner Stage 4.8 +/−0.6. Total bone mineral content (BMCTOT), and total (BMDTOT) bone mineral density, cortical thickness and area (CSAcort), muscle cross-sectional area (mCSA) and the CSAcort/mCSA ratio were measured at the 66 % length of the proximal tibia (PT) using peripheral quantitative computed tomography (pQCT 2000, Stratec, Pforzheim, Germany). BMCTOT, CSAcort TOT and mCSA were also measured at the proximal radius (PR-66% length). RESULTS: PR BMCTOT of the skiers was not significantly different (98.99 +/− 18.87mg/mm) than controls (94 +/− 20mg/mm). Likewise, PT CSAcort, mCSA, as well as the CSAcort/mCSA ratios were similar between skiers and controls. Cortical thickness and BMDTOT at the PT were significantly higher in skiers (5.423+/−0.254mm p = 0.000; 649.3 +/− 65.6mg/cm3 p = 0.0064) than controls (3.909+/−0.467mm; 574.1+/−56.5mg/cm3). A difference was seen in the CSAcort/mCSA ratio between PR (0.022 +/− 0.004) and PT (0.048 +/− 0.005) suggesting differences in muscle-bone relations between load bearing and non-load bearing limbs in adolescent male cross-country skiers. CONCLUSION: Cross-country skiers had increased cortical thickness and BMDTOT at the PT compared to ND and a higher cortical bone/muscle area ratio at the PT compared to the PR, suggesting regional variability in the muscle-bone relation. Supported in part by Stratec, Pforzheim, Germany.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".