DOES TIBIAL BONE STRUCTURE DIFFER BETWEEN GIRLS WHO COMPLETED A 20-MONTH EXERCISE INTERVENTION AND CONTROLS?
Bibliographic record
Abstract
INTRODUCTION We have previously shown that girls who participated in a 20-month school-based exercise intervention gained approximately 5% more bone mass at the femoral neck (FN, measured by DXA) compared with same maturity control girls. However, only one study has evaluated the bone structural response to loading (by pQCT) in girls following a 9-month exercise trial. PURPOSE To examine differences in bone structure and strength at the tibia between girls who completed a 20-month exercise intervention and controls. METHODS We assessed bone structure and strength of the left tibia in 54 girls who participated in our Healthy Bones II Study (24 intervention (INT), 30 controls (CON). The 20-month intervention involved 10 minutes, 3x/week of loaded exercise performed during school physical education. We used pQCT (Norland XCT-2000) to measure trabecular area (cm2), trabecular density (mg/cm3), total bone area (cm2), and total density (mg/cm3) at the distal (10%) site. Cortical area (CA, cm2), cortical thickness (cm), periosteal and endosteal circumferences (cm) and cross sectional moment of inertia (cm4) were measured at the midshaft (50%). Height (ht) and weight (wt) were measured using standard procedures. Pubertal maturation was assessed using Tanner Staging (TS). General physical activity (PA) was assessed by questionnaire. RESULTS There was no difference between groups for age (12.2±0.5 yrs), ht (154.6±8.1 cm), wt (48.8±11.2 kg) or PA. CON girls were significantly more mature than INT girls (X2, P < 0.05). There was no difference between groups for bone strength or structural parameters (ANCOVA, ht, TS, PA and age as covariates). PA was significantly associated with CA (p < 0.05). CONCLUSION Despite significantly greater gains in FN BMC following a 20-month exercise intervention, there was no difference in bone structure or strength at the tibia between INT and CON girls. Although our results support the notion that bone response to loading is region and site specific, these conclusions are tempered by the nature of cross-sectional comparisons.
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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 | 0.001 |
| 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 | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".