91236556 The relationship between bone mineral content and muscular strength and endurance in older adult women

Purpose: Moderate-to-vigorous physical activity (MVPA) positively influences bone mineral content (BMC) in prepubertal children, but it is unknown whether this relationship is partially mediated by free leptin index. The aim of this study was to examine whether the relationship between MVPA and total body less head (TBLH) BMC is mediated or moderated by free leptin index in prepubertal children. Methods: We performed a cross-sectional analysis on 401 children (194 girls) from baseline examinations of the Physical Activity and Nutrition in Childhood Study. We applied the four-way decomposition mediation analysis method to assess whether free leptin index, measured from fasted blood samples, mediated the relationship between accelerometer-measured MVPA and TBLH BMC measured by dual-energy X-ray absorptiometry. Results: MVPA had a positive controlled direct effect on TBLH BMC in girls and boys (β = 0.010 to 0.011, p < 0.05). There was no mediation or interaction between MVPA, free leptin index and TBLH BMC in girls or boys (β = −0.000 to 0.001, p > 0.05). Conclusion: Our study indicates that MVPA positively influences TBLH BMC through pathways not related to free leptin index in predominantly normal-weight prepubertal children, likely primarily through mechanical loading. The relationships between MVPA, free leptin index and TBLH BMC may be influenced by other factors such as pubertal status and adiposity, so it is unknown whether these observations extend to overweight and obese children at different stages of puberty.

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Abstract P615: Stress-Induced Changes in Total Bone Mineral Content and Total Bone Mineral Density due to Activation of the Renin-Angiotensin-Aldosterone System in Adolescent Females

Hypertension ◽

10.1161/hyp.68.suppl_1.p615 ◽

2016 ◽

Vol 68 (suppl_1) ◽

Author(s):

Vishwajeeth Pasham ◽

Deborah Stewart ◽

Laura Carbone ◽

Gregory A Harshfield

Keyword(s):

Bone Mineral Density ◽

Bone Mineral Content ◽

Bone Metabolism ◽

Bone Mineral ◽

Mineral Content ◽

Mineral Density ◽

Renin Angiotensin Aldosterone System ◽

Total Bone Mineral Density ◽

Total Bone Mineral Content ◽

The Relationship

Background: Previous literature has shown a strong negative effect of angiotensin II (ANGII) on bone metabolism within mouse models. Additionally, psychological stress has been associated with activation of the renin-angiotensin-aldosterone system (RAAS). Stress has also been related to lower total bone mineral density (TBMD). However, there is controversy in the literature examining the relationship between the RAAS and bone metabolism within humans and stress has not been considered as a direct link between these systems. Purpose: We aimed to examine the relationship between stress-induced RAAS activation and TBMD and total bone mineral content (TBMC). Methods: Participants were placed on a sodium controlled diet for three days. Participants then underwent two hours rest, one hour mental stressor, and two hours recovery with hourly collections of blood/urine samples. Renin, ANGII, aldosterone, TBMD and TBMC were measured. Results: This study recruited 586 adolescents (mean age 16±1.116) with 51% women and 62% African-American and 38% Caucasian. Overall, relationships were observed between ANGII and aldosterone, and TBMC and TBMD controlling for age, race, and BMI. During stress, aldosterone was related to TBMD (r=-.150, p<0.05) and ANGII was related to TBMC (r=-.156, p<0.05) and TBMD (r=-.139, p<0.05). When comparing males and females, only females demonstrated a relationship between TBMC and ANGII in response to stress (stress: r=-.229, p<0.05; post-stress: r=-.277, p<0.01) and between aldosterone and TBMC (stress: r=-.199, p<0.05) and TBMD (stress: r=-.250, p<0.01). Renin was not significantly correlated with TBMD nor TBMC in any population. Conclusion/Interpretations: These data suggest that stress-induced RAAS activation may be associated with lower TBMD and TBMC in girls. Despite small correlations, consistency across multiple measures of RAAS activation being apparent in adolescents is significant. This observation may indicate that stress activation of RAAS contributes to bone remodeling in early life.

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