Total and femoral neck bone mineral density and physical activity in a sample of men and women

Changes in the concentration of bone turnover markers in men after maximum intensity exercise

Background

Physical activity is an important factor in modelling the remodelling and metabolism of bone tissue. The aim of the study was to evaluate the changes in indices demonstrating bone turnover in men under the influence of maximum-intensity exercise.

Methods

The study involved 33 men aged 20-25, divided into two groups: experimental (n = 15) and control (n = 18). People training medium- and long-distance running were assigned to the experimental group, and non-training individuals to the control. Selected somatic, physiological and biochemical indices were measured. The level of aerobic fitness was determined using a progressively increasing graded test (treadmill test for subjective fatigue). Blood samples for determinations were taken before the test and 60 minutes after its completion. The concentration of selected bone turnover markers was assessed: bone fraction of alkaline phosphatase (b-ALP), osteoclacin (OC), N-terminal cross-linked telopeptide of the alpha chain of type I collagen (NTx1), N-terminal propeptide of type I progolagen (PINP), osteoprotegerin (OPG). In addition, the concentration of 25(OH)D3 prior to the stress test was determined. Additionally, pre and post exercise, the concentration of lactates in the capillary blood was determined.

Results

When comparing the two groups, significant statistical differences were found for the mean level of: 25(OH)D3 (p = 0.025), b-ALP (p < 0.001), OC (p = 0.004) and PINP (p = 0.029) prior to the test. On the other hand, within individual groups, between the values pre and post the stress test, there were statistically significant differences for the average level of: b-ALP (p < 0.001), NTx1 (p < 0.001), OPG (p = 0.001) and PINP (p = 0.002).

Conclusion

A single-session maximum physical effort can become an effective tool to initiate positive changes in bone turnover markers.

Factors Associated with Bone Mineral Density and Bone Resorption Markers in Postmenopausal HIV-Infected Women on Antiretroviral Therapy: A Prospective Cohort Study

The study aimed to determine factors associated with changes in bone mineral density (BMD) and bone resorption markers over two years in black postmenopausal women living with human immunodeficiency virus (HIV) on antiretroviral therapy (ART). Women (n = 120) aged > 45 years were recruited from Potchefstroom, South Africa. Total lumbar spine and left femoral neck (LFN) BMD were measured with dual energy X-ray absorptiometry. Fasting serum C-Telopeptide of Type I collagen (CTx), vitamin D and parathyroid hormone were measured. Vitamin D insufficiency levels increased from 23% at baseline to 39% at follow up. In mixed linear models serum CTx showed no change from baseline to end (p = 0.363, effect size = 0.09). Total and LFN BMD increased significantly over two years, but effect sizes were small. No significant change in spine BMD over time was detected (p = 0.19, effect size = 0.02). Age was significantly positively associated with CTx over time, and negatively with total and LFN BMD. Physical activity (PA) was positively associated with LFN BMD (p = 0.008). Despite a decrease in serum vitamin D, BMD and CTx showed small or no changes over 2 years. Future studies should investigate PA interventions to maintain BMD in women living with HIV.

Physical and lifestyle factors associated with trabecular bone score values

TBS is associated with age, weight, childhood physical activity, and BMD in men and age, height, BMD, and mobility in women.

INTRODUCTION

Trabecular bone score (TBS) indirectly assesses trabecular microarchitecture at the lumbar spine, providing complementary information to areal BMD. Many studies have investigated the relationships between BMD and lifestyle factors known to affect bone, but such research is limited for TBS. The aim of this study was to assess the relationship between TBS and lifestyle factors in Australian men and women.

METHODS

This cross-sectional study involved 894 men and 682 women (ages 24-98 years) enrolled in the Geelong Osteoporosis Study. TBS was assessed by analysis of lumbar spine DXA scans (Lunar Prodigy) using TBS iNsight software (Version 2.2). Bivariate and multivariable linear regression models were used to explore the associations between TBS and physical and lifestyle factors, including anthropometry, alcohol consumption, childhood physical activity, mobility, smoking status, prior low trauma fracture, medication use, and intakes of calcium and vitamin D.

RESULTS

In bivariate regression modelling, low mobility and the use of antiresorptive medication were associated with lower TBS in both men and women. Low childhood physical activity was also associated with lower TBS in men. Prior fracture, use of glucocorticosteroids, and total calcium intake were also associated with lower TBS in women. The final adjusted model for men included age, weight, childhood physical activity, and BMD, and for women, age, height, BMD, and mobility. No interaction terms were identified in the models.

CONCLUSIONS

Lower TBS is associated with older age, increased weight, low childhood physical activity, and lower BMD in men and older age, shorter stature, lower BMD, and low mobility in women.

Bone mineral density, hand grip strength, smoking status and physical activity in Polish young men

The human skeleton undergoes constant changes encompassing the phases of growth, consolidation and involution of the bone tissue. The aim of the research was to assess the relationship between bone mineral density (BMD) and such factors as hand grip strength, somatic structure or attitudes to tobacco smoking in men with different levels of physical activity. The study included 172 males aged 20-30 years. Mineral density and forearm bone mass were measured using the dual-energy X-ray absorptiometry method. Physical activity levels were assessed with the use of the International Physical Activity Questionnaire. Hand grip strength was measured with Jamar hand dynamometer. Attitudes towards smoking were assessed using the Global Adult Tobacco Survey. The correlation between a high level of physical activity among men and higher BMD and bone mass both in the distal and proximal parts of the forearm was statistically significantly greater compared to individuals with an insufficient level of physical activity. A better state of BMD and higher bone mass in both forearm bones was noted among non-smoking men. A high level of physical activity was the most significant predictor of BMD in the distal part of the forearm. The regression analysis in the proximal part revealed that body mass and a high level of physical activity were the most important predictors of BMD. The lack of physical activity was associated with more frequent occurrence of low bone mass in men. Tobacco smoking may be one of the most important risk factors of poor bone mineralization in young men.

Health Status and Lifestyle Habits of US Medical Students: A Longitudinal Study

Background:

Evidence shows that physicians and medical students who engage in healthy lifestyle habits are more likely to counsel patients about such behaviors. Yet medical school is a challenging time that may bring about undesired changes to health and lifestyle habits.

Aims:

This study assessed changes in students' health and lifestyle behaviors during medical school.

Subjects and Methods:

In a longitudinal study, students were assessed at both the beginning and end of medical school. Anthropometric, metabolic, and lifestyle variables were measured at a clinical research center. Data were collected from 2006 to 2011, and analyzed in 2013–2014 with SAS version 9.3. Pearson's correlations were used to assess associations between variables and a generalized linear model was used to measure change over time.

Results:

Seventy-eight percent (97/125) of participants completed both visits. At baseline, mean anthropometric and clinical measures were at or near healthy values and did not change over time, with the exception of increased diastolic blood pressure (P = 0.01), high-density lipoprotein-cholesterol (P < 0.001), and insulin (P < 0.001). Self-reported diet and physical activity habits were congruent with national goals, except for Vitamin D and sodium. Dietary intake did not change over time, with the exceptions of decreased carbohydrate (percent of total energy) (P < 0.001) and sodium (P = 0.04) and increased fat (percent of total energy) and Vitamin D (both P < 0.01). Cardiovascular fitness showed a trend toward declining, while self-reported physical activity increased (P < 0.001).

Conclusions:

Students' clinical measures and lifestyle behaviors remain generally healthy throughout medical school; yet some students exhibit cardiometabolic risk and diet and activity habits not aligned with national recommendations. Curricula that include personal health and lifestyle assessment may motivate students to adopt healthier practices and serve as role models for patients.

Lean Mass Appears to Be More Strongly Associated with Bone Health than Fat Mass in Urban Black South African Women

OBJECTIVES

To examine the association between body composition (fat mass, lean mass and body mass index, BMI) and bone health (bone mineral density, BMD and fracture risk) in urban black South African women.

DESIGN

A cross sectional study examining associations between body composition, dietary intake (food frequency questionnaire), habitual physical activity (Activity energy expenditure (AEE) measured using an accelerometer with combined heart rate monitor and physical activity questionnaire) and bone health (BMD using dual-energy X ray absorptiometry, DXA and fracture risk).

SETTING

Urban community dwellers from Ikageng in the North-West Province of South Africa.

PARTICIPANTS

One hundred and eighty nine (189) healthy postmenopausal women aged ≥43 years.

RESULTS

Fat mass and lean mass were significantly associated with BMD and fracture risk when adjusted for potential confounders. However, lean mass and not fat mass remained significantly associated with femoral neck BMD (β = 0.49, p <0.001), spine BMD (β = 0.48, p< 0.0001) and hip BMD (β = 0.59, p< 0.0001). Lean mass was also negatively associated with fracture risk (β = -0.19 p =0.04) when both lean and fat mass were in the same model.

CONCLUSION

Lean mass and fat mass were positively associated with femoral neck, spine and hip BMDs and negatively associated with fracture risk in urban black South African women. Our finding suggests that increasing lean mass rather than fat mass is beneficial to bone health. Our study emphasises the importance of positive lifestyle changes, intake of calcium from dairy and adequate weight to maintain and improve bone health of postmenopausal women.

Beneficial association of serum ghrelin and peptide YY with bone mineral density in the Newfoundland population

BACKGROUND

Ghrelin and peptide YY (PYY) are appetite regulating hormones secreted from the gastrointestinal tract (gut). Aside from their known effect on energy homeostasis, accumulating data indicates that these gut hormones also affect bone metabolism. However, data regarding the influence of ghrelin and PYY on bone density in humans is very limited, and the results are inconclusive. Therefore, this study was designed to investigate the potential association between circulating ghrelin and PYY with bone density indices in the general population.

METHODS

A total of 2257 adult subjects from the CODING (Complex Diseases in the Newfoundland Population: Environment and Genetics) study participated in this investigation. Acylated ghrelin and total PYY were measured in serum after a 12-hour fasting, with the Enzyme- Linked Immunosorbent Assay (ELISA) method. Bone mineral density was measured by dual-energy X-ray absorptiometry at the spine, femoral neck, and total hip. Multiple regression analyses adjusting for age, BMI, physical activity, smoking, and alcohol consumption were employed to analyze the association between serum ghrelin and PYY with bone mineral density parameters.

RESULTS

Significant positive associations of ghrelin concentration with L2-L4 BMD, L2-L4 Z-score, femoral neck BMD, femoral neck Z-score, total hip BMD, and total hip Z-score were found in women. No significant correlations between ghrelin and bone density indices were present in men. After dividing the female group into pre-menopausal and post-menopausal, ghrelin was positively correlated with femoral neck Z-score, and total hip Z-score in pre-menopausal women and L2-L4 BMD, and Z-score in post-menopausal group. Moreover, no significant association was discovered between serum PYY and bone density at any site.

CONCLUSION

Our results suggest a beneficial association of circulating ghrelin concentration with bone density in women at the population level. This association is independent of major confounding factors including BMI, physical activity, age, alcohol consumption, and smoking. Effect of menopause on this association seemed to be site specific. However, PYY does not seem to be associated with bone density parameters.

Low bone mass is prevalent in male-to-female transsexual persons before the start of cross-sex hormonal therapy and gonadectomy

OBJECTIVE

Cross-sex hormonal therapy and sex reassignment surgery (including gonadectomy) in transsexual persons has an impact on body composition and bone mass and size. However, it is not clear whether baseline differences in bone and body composition between transsexual persons and controls before cross-sex hormonal therapy play a role.

DESIGN

A cross-sectional study with 25 male-to-female transsexual persons (transsexual women) before cross-gender sex steroid exposure (median age 30 years) in comparison with 25 age-matched control men and a male reference population of 941 men.

MAIN OUTCOME MEASURES

Areal and volumetric bone parameters using respectively dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT), body composition (DXA), grip strength (hand dynamometer), Baecke physical activity questionnaire, serum testosterone and 25-OH vitamin D.

RESULTS

Transsexual women before cross-sex hormonal therapy presented with less muscle mass (p≤0.001) and strength (p≤0.05) and a higher prevalence of osteoporosis (16%) with a lower aBMD at the hip, femoral neck, total body (all p<0.001) and lumbar spine (p=0.064) compared with control men. A thinner radial cortex (p≤0.01) and lower cortical area at the radius and tibia (both p<0.05) was found in transsexual women vs. control men. Serum testosterone was comparable in all 3 groups, but 25-OH vitamin D was lower in transsexual women (p≤0.001).

CONCLUSIONS

Transsexual women before the start of hormonal therapy appear to have lower muscle mass and strength and lower bone mass compared with control men. These baseline differences in bone mass might be related to a less active lifestyle.