Submitted by Michael Groessner, MD
Effects of Repetitive Loading on the Growth-Induced Changes in Bone Mass
and Cortical Bone Geometry: a 12-month Study in Pre/Peri- and
Postmenarcheal Tennis Players
Ducher G, Bass SL, Saxon L, Daly RM
SOURCE
Noll Laboratory, Penn State University, University Park, PA 16802, USA. gxd25@psu.edu
ABSTRACT
Pre- and early puberty may be the most opportune time to strengthen the female skeleton, but there are few longitudinal data to support this claim. Competitive female premenarcheal (pre/peri, n = 13) and postmenarcheal (post, n = 32) tennis players aged 10 to 17 years were followed over 12 months. The osteogenic response to loading was studied by comparing the playing and
nonplaying humeri for dual-energy X-ray absorptiometry (DXA) bone mineral content (BMC) and magnetic resonance imaging (MRI) total bone area (ToA), medullary area (MedA), cortical area (CoA), and muscle area (MCSA) at the humerus. Over 12 months, growth-induced gains (nonplaying arm) in BMC, ToA, and CoA were greater in pre/peri (10% to 19%, p < .001) than in post (3% to 5%, p < .05 to .001) players. At baseline, BMC, ToA, CoA, and MCSA were 8% to 18% greater in the playing versus nonplaying arms in pre/peri and post players (all p < .001);
MedA was smaller in the playing versus nonplaying arms in post only players (p < .05). When comparing the annual gains in the playing arm relative to changes in the nonplaying arm, the increases in ToA and CoA were greater in pre/peri than post players (all p < .05). The smaller the side-to-side differences in BMC and CoA at baseline, the larger the exercise benefits at 12 months (r = -0.39 to -0.48, p < .01). The exercise-induced change in MCSA was predictive of the exercise benefits in BMC in pre/peri players only (p < .05). In conclusion, both pre/peri- and postmenarcheal tennis players showed significant exercise-induced skeletal benefits within a year, with greater benefits in cortical bone geometry in pre/perimenarcheal girls.
REVIEW
This study proves the bone-related benefits in both pre/peri- and post-menarcheal tennis players over the course of a single year. This aids in counseling young women that while the pre and peri-menarcheal years may be the ideal time to maximize bone structural properties, the post- menarcheal years are still an important time for continued exercise training in order to optimize peak bone mass.
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