Does Frequency of Resistance Training Effect Cortical Density at the Tibia in Older Women?: A pQCT Study
Bibliographic record
Abstract
ACSM guidelines recommend resistance training (RT) 2 to 3 times/week to optimize bone health. However, the effect of the frequency of RT on bone outcomes has not been evaluated in older community-dwelling women. PURPOSE: Our primary objective was to determine the effect of a 12-month program of three different RT frequencies (0, 1 and 2 times/week) on tibial cortical bone volumetric density (CovBMD) in healthy, community dwelling women aged 65-75 years. METHODS: This was an a priori secondary analysis of a randomized controlled trial (primary outcome was cognitive function). We randomized participants to one of three groups: (i) twice a week balance and tone group (i.e. no resistance other than body weight; BT); (ii) once a week RT program (RT1); and (iii) twice a week RT program (RT2). We used Keiser air-pressure resistance machines (Keiser Corporation, USA) for strengthening the upper and lower extremities. All exercise classes were delivered in groups of 8-10 participants and continued for 12 months. We used peripheral quantitative computed tomography (pQCT; Stratec XCT 2000, Germany) to acquire one 2.5 mm scan at the 50% site of the left tibia. Data were collected at baseline, 6 and 12 months. We used ANCOVA to determine the effect of the exercise intervention on tibial CovBMD at 6 and 12 months. RESULTS: We assessed 140 participants at baseline and 100 women provided data at all three time points (71% compliance). Baseline mean age for RT2 (n=34) and RT1 (n=35) groups was 69±3 years, and 70±3 years for BT (n=31). BMI for RT2 was 27±5, 26±5 for RT1 and 26±4 for BT group. Baseline mean Six-Minute Walk Test (meters) was 508±107 (RT2), 529±61 (RT1), and 537±68 (BT). The baseline mean tibial CovBMD (mg/cm3) at the 50% site was: 1055.8±65.2 (RT2), 1094.7±34.2 (RT1), and 1080.3±44.2 (BT). At 6 months the percent change in tibial CovBMD for the RT2 group= -0.2%; RT1= -0.04%; and BT= 0.2% for BT. From baseline to 12 months the percent change in tibial CovBMD for the RT2 group was -0.3%; RT1= -0.1%; and BT= -0.2%. After adjusting for baseline tibial CovBMD, there were no significant differences between groups at 6 months or 12 months. CONCLUSION: Tibial cortical bone density for all exercise interventions (RT2, RT1 and BT) was maintained in older community dwelling women over 12 months.
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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 | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| 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 | 0.001 | 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".