A 2-YEAR, SCHOOL-BASED EXERCISE INTERVENTION INDUCES SUBSTANTIAL GAIN IN FEMORAL NECK BMC IN BOYS
Bibliographic record
Abstract
PURPOSE We, and others, have reported greater gains in bone mass (BMC) at several skeletal sites in children participating in short-term (8 month) exercise interventions. However, whether benefits are maintained or increase when exercise is sustained over 20 months is unknown. METHODS We investigated BMC changes in initially, prepubertal boys (Tanner Stage (TS) 1, 10.1 (0.5) yr) who participated for 2 school years in a circuit-training intervention, 3x/wk. Intervention (INT) group (N = 28, 141.2 cm and 37.7 kg) was compared with controls (N = 32, 140.7 cm and 34.6 kg) whose schools continued normal-practice PE. We assessed BMC (grams) and area (BA, cm) for the total body (TB), lumbar spine, proximal femur, femoral neck (FN) and greater trochanter by DXA (Hologic QDR 4500W). We obtained lean mass and fat mass (grams) from DXA TB scans, and measured height (cm) and weight (kg) by standard methods. Physical activity (PA) and calcium intake (CI) were evaluated by questionnaire 6 times over 2 school years. RESULTS There was no difference between groups for body size or composition, maturity, CI or PA at baseline. Over 20 months, two-thirds of the boys advanced to TS 2 or 3. FN BMC (18.6 vs 13.9%, P < 0.01) and BA (11.1 vs 7.6%, P < 0.05), and TB BMC (24.7 vs 22.9%, P < 0.05) increased significantly more in INT (ANCOVA, baseline weight, final TS, PA and height change as covariates). Bone changes at other sites were not significant. Changes in FN BMC paralleled changes in lean mass, which were augmented in INT (23.1 vs 18.4%, P < 0.05). Other growth indices changed similarly between groups. In regression, group assignment was a significant predictor of FN BMC change and accounted for 5.7% (P < 0.01) of variance (baseline BMC, final TS, change in lean mass, baseline weight, height change and PA were controlled in the model). CONCLUSION Our data suggests that substantial increases in FN BMC can be made with long term participation in a school-based exercise program. The early pubertal period may be a particularly responsive time for femoral neck adaptation to loading activity.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.002 | 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".