Background: Exercise stimulates bone remodeling and improves insulin sensitivity (Si), even without associated weight loss. Osteocalcin (OCN), a bone-derived protein, is associated with improved Si. Purpose: We examined how daily physical activity is associated with OCN and Si. Methods: Physical activity was measured through questionnaires completed in Minneapolis from 2010 to 2012. A physical activity score (PAQsum) was calculated to quantify physical activity (range 1-5). OCN and bone specific alkaline phosphatase (BAP) were measured by ELISA. Si was measured by the insulin modified frequently sampled IV glucose tolerance test. Results: The mean PAQsum value was 2.4 ± 0.8 in 47 participants (12-17.9. years old). PAQsum was positively associated with OCN (p = 0.006). Participants with PAQsum < 2 had significantly lower OCN levels compared to participants with PAQsum > 2 (p. <. 0.02). Obesity did not modify the association between PAQsum and OCN. There was no statistically significant association between PAQsum and Si or between OCN and Si, even after adjustment for percent body fat. Conclusions: OCN is higher in more physically active individuals. More research is needed to clarify the relationship between OCN, physical activity and Si.
Bibliographical noteFunding Information:
We gratefully acknowledge the study participants and parents as well as Jane Kennedy, R.N., who made this project possible. This project was supported by Grant Number K23AR057789 from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) , by the Irvine McQuarrie Clinical Research Scholar Award , and by Grant Number 8UL1TR000114-02 from the National Center for Advancing Translational Sciences (NCATS) and Translational Science Institute (CTSI) . Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the CTSI or the NIH.
LEP, WT, BF, SC, and ASK have nothing to declare. BN receives grant support from Medtronic ( NCT01991470 ).
- Physical activity