Skip Navigation LinksHome > May 2003 - Volume 35 - Issue 5 > DOES TIBIAL BONE STRUCTURE DIFFER BETWEEN GIRLS WHO COMPLETE...
Medicine & Science in Sports & Exercise:
H-13E Free Communication/Slide Mechanics of Bone and Connective Tissue

DOES TIBIAL BONE STRUCTURE DIFFER BETWEEN GIRLS WHO COMPLETED A 20‐MONTH EXERCISE INTERVENTION AND CONTROLS?

Macdonald, H M.1; MacKelvie, K J.1; MacLean, L B.1; McKay, H A.1

Free Access
Article Outline
Collapse Box

Author Information

1University of British Columbia, Vancouver, British Columbia

Back to Top | Article Outline

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.

Back to Top | Article Outline

PURPOSE

To examine differences in bone structure and strength at the tibia between girls who completed a 20-month exercise intervention and controls.

Back to Top | Article Outline

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.

Back to Top | Article Outline

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).

Back to Top | Article Outline

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.

©2003The American College of Sports Medicine

Login

Article Tools

Share

Connect With Us