Effects of multiparity and prolonged breast-feeding on maternal bone mineral density: a community-based cross-sectional study

© 2009 Lenora et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Physical activity, muscle function, falls and fractures

STUDY DESIGN: A thematic review. OBJECTIVES: To evaluate if physical activity enhances muscle strength, improves balance, and reduces the fall frequency and the fracture incidence. BACKGROUND: One of the major medical problems of today is the increasing incidence of fragility fractures. Muscle strength and fall is one of the major determinants of a fracture. If physical activity could increase muscle strength, improve balance and reduce the fall frequency, then training could be recommended as prevention for fractures. METHODS: The review used Medline (Pub Med) and the search words exercise, physical activity, muscle strength, balance, falls, fractures. Randomized controlled trials (RCT) were predominantly included, although this not is a systematic review. RESULTS: The evidence that physical activity modifies the risk factors for fall is compelling, although RCT with fractures as end point are lacking. Physical activity is associated with improved muscle strength, co-ordination and balance. Physical training increases muscle strength also in octogenarians by up to 200%, i.e. a much more pronounced effect than the corresponding increase in muscle volume or bone mass. There is also evidence that physical activity decreases the actual number of falls. Observational cohort and case-control studies imply that physical activity is associated with reduced hip fracture risk. If exercise reduces the number of vertebral fractures and other fragility fractures are less evaluated. CONCLUSIONS: Physical activity in older ages can be recommended to improve muscle strength and balance, to reduce the risk to fall and fractures, although the highest level of evidence - RCT with fracture as endpoint - is lacking

Effects of an 8-year childhood physical activity intervention on musculoskeletal gains and fracture risk

Background Physical activity (PA) in childhood is associated with musculoskeletal benefits while the effect on fracture risk is yet to be determined. The aim of this study was to evaluate whether extension of a PA intervention leads to improvement in musculoskeletal traits with an accompanied reduced fracture risk. We hypothesized that the PA program would have beneficial effects in both sexes, but more so in girls since they tend to be less physically active than boys during this time frame. Methods In one elementary school we increased physical education (PE) from 60 to 200 min per school week and followed 65 girls and 93 boys from a mean age of 7 years until a mean age of 15 years. Thirty-nine girls and 37 boys in three other schools continued with 60 min of PE per week during the same years and served as controls. We measured bone mineral content (BMC), areal bone mineral density (aBMD), and bone area annually with dual energy X-ray absorptiometry, and leg muscle strength with a computerized dynamometer. In 3534 children within the same PE program (1339 in the intervention and 2195 in the control group) we registered incident fractures during the 8-year study period and estimated annual sex-specific fracture incidence rate ratios (IRRs). Results Girls in the intervention group annually gained more total body less head aBMD, spine aBMD (p < 0.01), femoral neck BMC (p < 0.05), lumbar vertebrae size (p < 0.05), and knee flexion strength (p < 0.05) than girls in the control cohort. In boys we found no group differences. There was an inverse correlation between number of years with extra PE and the annual IRR of sustaining fractures in both girls (r = − 0.90 (95% CI − 0.98 to − 0.51); p < 0.001) and boys (r = − 0.74 (95% CI − 0.94 to − 0.02); p < 0.05). Conclusion In this 8-year pediatric school-based moderate exercise intervention program there is an inverse correlation in both sexes between annual IRR and each additional year of extra PA. A sub-cohort of girls in the intervention group had greater gains in bone mass, bone size, and muscle strength, which could possibly explain the inverse correlation between years within the PA program and fracture risk, while in boys the reason for the inverse correlation remains unknown. It should be noted that differences in unreported factors such as skeletal maturity status, diet, and spare time PA could confound our inferences. That is, true causality cannot be stated

A School-Based Exercise Intervention Program Increases Muscle Strength in Prepubertal Boys

This prospective controlled intervention study over 12 months evaluated the effect of exercise on muscular function, physical ability, and body composition in pre-pubertal boys. Sixty-eight boys aged 6–8 years, involved in a general school-based exercise program of 40 min per school day (200 min/week), were compared with 46 age-matched boys who participated in the general Swedish physical education curriculum of mean 60 min/week. Baseline and annual changes of body composition were measured by dual energy X-ray absorptiometry (DXA), stature, and body mass by standard equipments, isokinetic peak torque (PT) of the knee extensors, and flexors at 60 and 180 deg/sec by computerized dynamometer (Biodex) and vertical jump height (VJH) by a computerized electronic mat. The annual gain in stature and body mass was similar between the groups whereas the increase in total body and regional lean mass (P < .001) and fat mass (P < .001) was greater in the exercise group. The one-year gain in body mass-adjusted knee extensor and flexor PT at 180 deg/sec was significantly greater in the intervention group compared with the control group (P < .01, adjusted for age at baseline and P < .001, adjusted for age and muscle strength at baseline, resp.). There was no group difference in VJH. In conclusion, the increase in school-based physical education from 60 to 200 minutes per week enhances the development of lean body mass and muscle strength in pre-pubertal boys

A school-curriculum-based exercise intervention program for two years in pre-pubertal girls does not influence hip structure

ABSTRACT: BACKGROUND: It is known that physical activity during growth has a positive influence on bone mineral accrual, and is thus possibly one strategy to prevent osteoporosis. However, as bone geometry, independent of areal bone mineral density (aBMD), influences fracture risk, this study aimed to evaluate whether hip structure in pre-pubertal girls is also affected by a two-year exercise intervention program. METHODS: Forty-two girls aged 7-9 years in a school-curriculum-based exercise intervention program comprising 40 minutes of general physical activity per school day (200 minutes per week) were compared with 43 age-matched girls who participated in the general Swedish physical education curriculum comprising a mean of 60 minutes per week. The hip was scanned by dual energy X-ray absorptiometry (DXA) and the hip structural analysis (HSA) software was applied to evaluate bone mineral content (BMC, g), areal bone mineral density (aBMD, g/cm2), periosteal diameter, cross-sectional area (CSA, cm2), section modulus (Z, cm3) and cross-sectional moment of inertia (CSMI, cm4) of the femoral neck (FN). Annual changes were compared. Subjective duration of physical activity was estimated by questionnaire and objective level of everyday physical activity at follow-up by means of accelerometers worn for four consecutive days. All children remained at Tanner stage 1 throughout the study. Group comparisons were made by independent student's t-test between means and analyses of covariance (ANCOVA). RESULTS: At baseline, the two groups did not differ with regard to age, anthropometrics or bone parameters. No between-group differences were observed for annual changes in the FN variables measured. CONCLUSION: A two-year school-based moderately intense general exercise program for 7-9-year-old pre-pubertal girls does not influence structural changes in the FN

Dual-Comb Swept Wavelength Interferometry

We demonstrate a hybrid swept wavelength interferometry-dual-comb spectroscopy system for fast broadband full-field measurements. Phase and amplitude retrieval is experimentally verified and compensation of laser sweep nonlinearity is demonstrated without external referencing

Real-Time Monitoring of Cable Break in a Live Fiber Network using a Coherent Transceiver Prototype

We monitor a 524km live network link using an FPGA-based sensing-capable coherent transceiver prototype during a human-caused cable break. Post-analysis of polarization data reveals minute-level potential warning precursors and baseline-exceeding changes directly preceding the break.Comment: 3 page

Reduction of the HIV-1 reservoir in resting CD4+ T-lymphocytes by high dosage intravenous immunoglobulin treatment: a proof-of-concept study

<p>Abstract</p> <p>Background</p> <p>The latency of HIV-1 in resting CD4⁺T-lymphocytes constitutes a major obstacle for the eradication of virus in patients on antiretroviral therapy (ART). As yet, no approach to reduce this viral reservoir has proven effective.</p> <p>Methods</p> <p>Nine subjects on effective ART were included in the study and treated with high dosage intravenous immunoglobulin (IVIG) for five consecutive days. Seven of those had detectable levels of replication-competent virus in the latent reservoir and were thus possible to evaluate. Highly purified resting memory CD4⁺T-cells were activated and cells containing replication-competent HIV-1 were quantified. HIV-1 from plasma and activated memory CD4⁺T-cells were compared with single genome sequencing (SGS) of the <it>gag </it>region. T-lymphocyte activation markers and serum interleukins were measured.</p> <p>Results</p> <p>The latent HIV-1 pool decreased with in median 68% after IVIG was added to effective ART. The reservoir decreased in five, whereas no decrease was found in two subjects with detectable virus. Plasma HIV-1 RNA ≥ 2 copies/mL was detected in five of seven subjects at baseline, but in only one at follow-up after 8–12 weeks. The decrease of the latent HIV-1 pool and the residual plasma viremia was preceded by a transitory low-level increase in plasma HIV-1 RNA and serum interleukin 7 (IL-7) levels, and followed by an expansion of T regulatory cells. The magnitude of the viral increase in plasma correlated to the size of the latent HIV-1 pool and SGS of the <it>gag </it>region showed that viral clones from plasma clustered together with virus from activated memory T-cells, pointing to the latent reservoir as the source of HIV-1 RNA in plasma.</p> <p>Conclusion</p> <p>The findings from this uncontrolled proof-of-concept study suggest that the reservoir became accessible by IVIG treatment through activation of HIV-1 gene expression in latently-infected resting CD4⁺T-cells. We propose that IVIG should be further evaluated as an adjuvant to effective ART.</p