A longitudinal comparison of appendicular bone growth and markers of strength through adolescence in a South African cohort using radiogrammetry and pQCT

To compare growth patterns and strength of weight- and non-weight-bearing bones longitudinally. Irrespective of sex and ethnicity, metacarpal growth was similar to that of the non-weight-bearing radius but differed from that of the weight-bearing tibia. Weight- and non-weight-bearing bones have different growth and strength patterns.

INTRODUCTION

Functional loading modulates bone size and strength.

METHODS

To compare growth patterns and strength of weight- and non-weight-bearing bones longitudinally, we performed manual radiogrammetry of the second metacarpal on hand-wrist radiographs and measured peripheral quantitative computed tomography images of the radius (65%) and tibia (38% and 65%), annually on 372 black and 152 white South African participants (ages 12-20 years). We aligned participants by age from peak metacarpal length velocity. We assessed bone width (BW, mm); cortical thickness (CT, mm); medullary width (MW, mm); stress-strain index (SSI, mm³); and muscle cross-sectional area (MCSA, mm²).

RESULTS

From 12 to 20 years, the associations between metacarpal measures (BW, CT and SSI) and MCSA at the radius (males R² = 0.33-0.45; females R² = 0.12-0.20) were stronger than the tibia (males R² = 0.01-0.11; females R² = 0.007-0.04). In all groups, radial BW, CT and MW accrual rates were similar to those of the metacarpal, except in white females who had lower radial CT (0.04 mm/year) and greater radial MW (0.06 mm/year) accrual. In all groups, except for CT in white males, tibial BW and CT accrual rates were greater than at the metacarpal. Tibial MW (0.29-0.35 mm/year) increased significantly relative to metacarpal MW (- 0.07 to 0.06 mm/year) in males only. In all groups, except white females, SSI increased in each bone.

CONCLUSION

Irrespective of sex and ethnicity, metacarpal growth was similar to that of the non-weight-bearing radius but differed from that of the weight-bearing tibia. The local and systemic factors influencing site-specific differences require further investigation. Graphical abstract.

Metacarpal Indices and Their Association with Fracture in South African Children and Adolescents

This prospective study assessed whether metacarpal indices predict fracture risk in children and adolescents. Radiogrammetry was performed at the second metacarpal midshaft on annual hand-wrist radiographs of 359 South African (SA) children aged 10-17 years. Bone length, bone width, and medullary width were measured, and the following proxies for bone strength calculated: metacarpal index (MCI), bone mineral density (BMD), section modulus (SM), stress-strain index (SSI), and slenderness index (SLI). Height and weight were measured annually. Self-reported physical activity (PA) and fracture history were obtained at ages 15 years (for the preceding 12 months) and 17 years, respectively. At 17 years, 82 (23%) participants (black, 16%; white, 42%; p < 0.001) reported a previous fracture. None of the bone measures or indices were associated with fracture in black participants. In white females, after adjusting for PA, a 1 standard deviation (SD) greater SLI doubled the fracture risk [odds ratio (OR) 2.08; 95% confidence interval (CI) 1.08, 3.98]. In white males, a 1 SD greater BMD was associated with a 2.62-fold increase in fracture risk (OR 3.62; 95% CI 1.22, 10.75), whilst a 1 SD greater SM (OR 2.29; 95% CI 1.07, 4.89) and SSI (OR 2.23; 95% CI 1.11, 4.47) were associated with a more than twofold increase in fracture risk, after height, and PA adjustment. No single index consistently predicted fracture across the four groups possibly due to ethnic and sex differences in bone geometry, muscle mass, and skeletal loading. Metacarpal radiogrammetry did not reliably predict fracture in SA children.

Cardiorespiratory fitness levels and associations with physical activity and body composition in young South African adults from Soweto

Background

This observational study aims to describe fitness, and objectively measured physical activity levels and patterns in 409 young black South African adults (aged 19–20 years) from Soweto, as well as to examine associations between physical activity, fitness and BMI.

Methods

A sub-maximal ramped step test was used to obtain an estimate of maximal oxygen uptake (VO_2max). Physical activity was measured using ActiGraph (GT1M) for 7 days in 256 participants. Time spent in sedentary (<100 counts per minute (cpm)), moderate (2020–5998 cpm) and vigorous (≥5999 cpm) intensity activity was calculated, and 90% of participants were considered active. Data are presented as mean(CI) or median(CI).

Results

Overweight and obesity was more prevalent in females than males (35% vs 8%, p < 0.001). Males had a higher VO_2max than females (41.9(41, 43) vs 32.6(32, 33)mlO₂/kg/min, p < 0.001); spent more time in moderate to vigorous intensity physical activity (MVPA) (83(80, 94) vs 43(38, 45)min/day, p < 0.001), and less time in sedentary behaviours (541(541, 567) vs 575(568, 597)min/day, p < 0.01). Sedentary time was not associated with VO_2max, however BMI was inversely associated, and MVPA was positively associated, with VO_2max (both p < 0.001).

Conclusions

The majority of young South African adults in this study were sufficiently active, and higher MVPA was associated with fitness. However, the high level of sedentary behaviour in this population is of concern and may be contributing to the increasing prevalence of overweight and obesity in this population. Young South African females are at greatest risk for decreased cardiovascular fitness and should be the focus for future interventions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-017-4212-0) contains supplementary material, which is available to authorized users.

Incidence and prevalence of type 2 diabetes mellitus with HIV infection in Africa: a systematic review and meta-analysis

OBJECTIVES

This systematic review aims to investigate the incidence and prevalence of type 2 diabetes mellitus (T2DM) in patients with HIV infection in African populations.

SETTING

Only studies reporting data from Africa were included.

PARTICIPANTS

A systematic search was conducted using four databases for articles referring to HIV infection and antiretroviral therapy, and T2DM in Africa. Articles were excluded if they reported data on children, animals or type 1 diabetes exclusively.

MAIN OUTCOME MEASURES

Incidence of T2DM and prevalence of T2DM. Risk ratios were generated for pooled data using random effects models. Bias was assessed using an adapted Cochrane Collaboration bias assessment tool.

RESULTS

Of 1056 references that were screened, only 20 were selected for inclusion. Seven reported the incidence of T2DM in patients with HIV infection, eight reported the prevalence of T2DM in HIV-infected versus uninfected individuals and five reported prevalence of T2DM in HIV-treated versus untreated patients. Incidence rates ranged from 4 to 59 per 1000 person years. Meta-analysis showed no significant differences between T2DM prevalence in HIV-infected individuals versus uninfected individuals (risk ratio (RR) =1.61, 95% CI 0.62 to 4.21, p=0.33), or between HIV-treated patients versus untreated patients (RR=1.38, 95% CI 0.66 to 2.87, p=0.39), and heterogeneity was high in both meta-analyses (I²=87% and 52%, respectively).

CONCLUSIONS

Meta-analysis showed no association between T2DM prevalence and HIV infection or antiretroviral therapy; however, these results are limited by the high heterogeneity of the included studies and moderate-to-high risk of bias, as well as, the small number of studies included. There is a need for well-designed prospective longitudinal studies with larger population sizes to better assess incidence and prevalence of T2DM in African patients with HIV. Furthermore, screening for T2DM using gold standard methods in this population is necessary.

TRIAL REGISTRATION NUMBER

PROSPERO42016038689.

Maternal and early life nutrition and physical activity: setting the research and intervention agenda for addressing the double burden of malnutrition in South African children

Early life is important for later health outcomes, yet there are few studies which adequately address all of the potential early life insults that may affect later life health and growth trajectories. This is particularly evident in low- to middle-income countries such as South Africa, where women of childbearing age are particularly vulnerable to high levels of physical inactivity, malnutrition, and obesity. Pregnancy may therefore be an opportune time to change behaviours and improve maternal and offspring health outcomes, and decrease the inter-generational transfer of risk. We show clear evidence that physical activity and nutrition are important target areas for intervention during pregnancy and in the early years of life, yet that current literature in Africa, and specifically South Africa, is limited. We have outlined the available literature concerning the impact of maternal and early life nutrition and physical activity on the health status of South African children, and have provided some recommendations for future research and policy.

A scoping review examining physical activity measurement and levels in the first 2 years of life

BACKGROUND

The first few years of life have been identified as a critical stage in the development of activity behaviours, which have been shown to track into later life. This scoping review aims to assess the literature reporting on physical activity levels in the first 2 years of life in order to answer two main questions: (i) how is physical activity measured in this age group? and (ii) how active are infants and toddlers in the first 2 years of life?

METHODS

A search strategy was employed using PubMed with restrictions only on age and language. After applying exclusion criteria, 20 papers were included in the results.

RESULTS

Seventeen studies used some form of objective assessment of physical activity (accelerometers, actometers, direct observation, doubly labelled water or a metabolic chamber); while the remaining three relied on subjective assessments (parent reported questionnaires or interviews, and activity diaries). Nine studies exclusively assessed infants (<12 months), and five exclusively assessed toddlers (>12 months). Only six studies reported physical activity levels and patterns specifically; most included studies measured activity as a covariate or correlate. Therefore, much of the reported data was difficult to assess, as results were vague or incompletely described. Where data were reported sufficiently for analysis, results were equally conflicted regarding whether toddlers were meeting recommended physical activity guidelines.

CONCLUSIONS

This scoping review re-iterates the fact that more studies need to be conducted, which focus primarily on measuring and reporting physical activity levels and patterns in this age group in a comprehensive and standardized way, so that more informed guidelines can be devised and interventions can be designed and implemented where necessary.

Impact of social norms and social support on diet, physical activity and sedentary behaviour of adolescents: a scoping review

The prevalence of non-communicable diseases (NCDs) in adulthood is rapidly increasing, and it is essential that risk factors for NCDs be addressed in adolescence, both for the health of individuals during adolescence and for their health in later life. These risk factors include diet, physical activity and sedentary behaviour. No literature has been published that comprehensively summarizes the impact of social norms and social support on these behaviours among adolescents. Therefore, a scoping review was conducted to determine the extent of recent (since 2000) literature available on this topic. A comprehensive search strategy was used to search PubMed and EMBASE for eligible reviews. Review papers (narrative reviews, systematic and non-systematic reviews) published in English in peer-reviewed journals from 2000 to February 2013 were included in the overview. Two of the authors screened the titles and abstracts of the search results independently. Thirty reviews were included in the scoping review. This scoping review has shown sufficient evidence for parental influences, and especially the positive impact of an authoritative parenting style, on healthy behaviours of adolescents, although the evidence is somewhat more compelling for diet than for physical activity and sedentary behaviour. More research is needed to investigate parental and family influences on physical activity and sedentary behaviour. And the effect of peer influences on diet, physical activity and sedentary behaviour of adolescents requires further investigation. The evidence presented affirms the consideration of social norms and social support in the development of interventions to address these behaviours in adolescents. The evidence regarding parenting style provides some concrete guidance for such interventions.

Osteogenic effects of a physical activity intervention in South African black children

OBJECTIVES

To determine whether a weight-bearing physical activity intervention improves measures of bone density, size and strength in a pre- and early pubertal cohort of black South African children.

METHODS

Twenty two school children (9.7±1.1 years) were cluster randomised into an exercise (EX; n=12) and control (CON; n=10) group. EX children performed a weight-bearing exercise program for 20 weeks. CON children continued their regular activities. Whole body DXA and tibial peripheral QCT scans were obtained. Urine was analysed for concentrations of cross-linked N-telopeptides of Type I collagen (NTX).

RESULTS

Changes in 4% volumetric BMD, area and strength were greater in EX than CON. At the 38% site, change in bone area and density was greater in EX than CON. The greater change in periosteal circumference in the EX groups also resulted in a greater change in cortical thickness of the tibia compared to the CON group. NTX concentration was lower in the EX group than the CON group after the intervention.

CONCLUSIONS

This study documents for the first time the beneficial response of trabecular and cortical bone of black children to a weight bearing exercise intervention.

The association between body composition, 25(OH)D, and PTH and bone mineral density in black African and Asian Indian population groups

CONTEXT AND OBJECTIVE

There are few data on the contribution of body composition to bone mineral density (BMD) in non-Caucasian populations. We therefore studied the contribution of body composition, and possible confounding of 25-hydroxyvitamin D and PTH, to BMD at various skeletal sites in black African (BA) and Asian Indian (AI) subjects.

DESIGN AND SETTING

This was a cross-sectional study in Johannesburg, South Africa.

PARTICIPANTS

BMD, body fat, and lean mass were measured using dual x-ray absorptiometry and abdominal fat distribution by ultrasound in 714 healthy subjects, aged 18-65 years.

RESULTS

Whole-body (subtotal), hip, femoral neck, and lumbar spine (lumbar) BMD were significantly higher in BA than AI subjects (P < .001 for all). Whole-body lean mass positively associated with BMD at all sites in both ethnic groups (P < .001 for all) and partially explained the higher BMD in BA females compared with AI females. Whole-body fat mass correlated positively with lumbar BMD in BA (P = .001) and inversely with subtotal BMD in AI subjects (P < .0001). Visceral adiposity correlated inversely with subtotal BMD in the BA (P = .037) and with lumbar BMD in the AI group (P = .005). No association was found between serum 25-hydroxyvitamin D and BMD. PTH was inversely associated with hip BMD in the BA group (P = .01) and with subtotal (P = .002), hip (P = .001), and femoral BMD (P < .0001) in the AI group.

CONCLUSIONS

Significant differences in whole-body and site-specific BMD between the BA and AI groups were observed, with lean mass the major contributor to BMD at all sites in both groups. The contribution of other components of body composition differed by site and ethnic group.

Fracture patterns and bone mass in South African adolescent-mother pairs: the Birth to Twenty cohort

The associations of fracture prevalence and bone mass in adolescents with maternal fracture history and bone mass have not been investigated previously in South Africa. Maternal bone mass has a significant inverse association with their adolescents' fracture rates and bone mass across all ethnic groups.

INTRODUCTION

Differences in fracture rates and bone mass between families and individuals of different ethnic origins may be due to differing lifestyles and/or genetic backgrounds. This study aimed to assess associations of fracture prevalence and bone mass in adolescents with maternal fracture history and bone mass, and sibling fracture history.

METHODS

Data from 1,389 adolescent-biological mother pairs from the Birth to Twenty longitudinal study were obtained. Questionnaires were completed on adolescent fractures until 17/18 years of age and on sibling fractures. Biological mothers completed questionnaires on their own fractures prior to the age of 18 years. Anthropometric and bone mass data on adolescent-biological mother pairs were collected.

RESULTS

An adolescent's risk of lifetime fracture decreased with increasing maternal lumbar spine (LS) bone mineral content (BMC; 24 % reduction in fracture risk for every unit increase in maternal LS BMC Z-score) and increased if they were white, male, or had a sibling with a history of fracture. Adolescent height, weight, male gender, maternal bone area and BMC, and white ethnicity were positive predictors of adolescent bone mass. White adolescents and their mothers had a higher fracture prevalence (adolescents 42 %, mothers 31 %) compared to the black (adolescents 20 %, mothers 6 %) and mixed ancestry (adolescents 20 %, mothers 16 %) groups.

CONCLUSION

Maternal bone mass has a significant inverse association with their adolescent off-springs' fracture risk and bone mass. Furthermore, there is a strong familial component in fracture patterns among South African adolescents and their siblings.

Near infrared reactance for the estimation of body fatness in regularly exercising individuals

Near infrared reactance (NIR) is used to measure body fat percentage (BF%), but there is little data on its use in non-obese, regularly exercising individuals. Therefore, this study aimed to examine the limits of agreement between NIR compared to dual x-ray absorptiometry (DXA) for the measurement of BF% in 2 cohorts of regularly exercising individuals. BF% was measured using DXA and NIR in a regular exercising (≥3 sessions/week), healthy active cohort (HA; n=57), and in a regularly exercising and resistance trained (≥2 sessions/week) cohort (RT; n=59). The RT cohort had lower BF% than the HA cohort (15.3±5.5% and 25.8±7.1%, P<0.001). In the HA and RT cohorts, NIR BF% was associated with DXA BF% (R2=0.72, SEE=3.7, p<0.001 and R2=0.50, SEE=4.1 p<0.001, respectively). In the HA cohort, NIR tended to under-predict BF% (mean difference: - 1.3%; 95% limits of agreement (LOA); - 8.8 to 6.2%) whereas in the RT cohort, NIR tended to over-predict BF% compared to DXA (mean difference: 1.1; 95% LOA; - 8.1 to 10.3%). In conclusion, NIR and DXA yield similar average BF% measurements in 2 cohorts of non-obese regularly exercising individuals. However, the rather broad LOA of NIR need to be considered when using NIR to screen for overweight and obesity, or measure and track changes in body composition.

Site-specific differences in bone mineral density in black and white premenopausal South African women

SUMMARY

We examined ethnic differences in bone mineral density (BMD) and the contribution of body composition, lifestyle and socioeconomic factors in South African women. Femoral neck and total hip BMD were higher, but lumbar spine BMD was lower in black women, with body composition, lifestyle and socioeconomic status (SES) factors contributing differently in ethnic groups.

INTRODUCTION

There is a paucity of data on the relative contribution of body composition, lifestyle factors and SES, unique to different ethnic groups in South Africa, to BMD. We examined differences in femoral neck (FN), total hip (TH) and lumbar spine (LS) BMD between black and white premenopausal South African women and the associations between BMD and body composition, lifestyle factors and SES in these two ethnic groups.

METHODS

BMD and body composition were measured in 240 black (27 ± 7; 18-45 years) and 187 white (31 ± 8; 18-45 years) women using dual-energy X-ray absorptiometry. Questionnaires were administered to examine SES, physical activity and dietary intake.

RESULTS

After co-varying for age, FN and TH were higher in black than white women (FN 0.882 ± 0.128 vs. 0.827 ± 0.116 g/cm(2), P < 0.001; TH 0.970 ± 0.130 vs. 0.943 ± 0.124 g/cm(2), P = 0.018). When adjusting for ethnic differences in body composition, LS was higher in white than black women. In black women, fat-free soft tissue mass, SES and injectable contraceptive use explained 33-42% of the variance in BMD at the hip sites and 22% at the LS. In white women, fat-free soft tissue mass and leisure activity explained 24-30% of the variance in BMD at the hip sites, whereas fat mass, leisure activity and oral contraceptive use explained 11% of the variance at the LS.

CONCLUSION

FN and TH BMD were higher, but LS BMD was lower in black than white South African women with body composition, lifestyle and SES factors contributing differently to BMD in these women.

Comparison of site-specific bone mass indices in South African children of different ethnic groups

This study reports on ethnic differences in bone mass before and after adjusting for differences in body size and bone area (BA). Lumbar spine (LSBMC), proximal femur (PFBMC) and femoral neck (FNBMC) bone mineral contents were measured in black ('black'; n = 263) and white ('white'; n = 73) children from Johannesburg and children of mixed ancestral origin ('mixed'; n = 64) from Cape Town, South Africa. Geometric estimates and the power coefficient from the regression analyses of BMC on BA were calculated. After adjusting for age, weight, and height, LSBMC in girls and FNBMC in girls and boys were greatest in mixed, followed by black and then white, groups. Mixed boys and girls also had greater PFBMC than their black and white peers, but only in the boys was PFBMC greater in the black than the white groups. When including BA in the adjustment, differences remained at the FN in boys and girls, and the LS and PF in girls, but disappeared at the PF in mixed and black boys. The difference in LSBMC between mixed and black boys became significant after adjustment for age, weight, height, and BA. Geometric estimates at the femoral neck were greater in the mixed group. Power coefficients were greater in the white group, suggesting differences in shape or bone distribution. In conclusion, this study suggests that, in addition to differences in BMC, differences in bone strength and geometry are present which might confer advantages to the bone of mixed-ancestry children.

Early life and current determinants of bone in South African children of mixed ancestral origin

BACKGROUND

The influence of early life factors on the bone mineral density of children has been identified, however the contribution of these determinants may vary.

AIM

The study investigated determinants of bone mineral content (BMC) in South African children of mixed ancestral origin.

SUBJECTS AND METHODS

Early life data including birth weight, maternal alcohol consumption and smoking during pregnancy were collected on 9-year-old children of mixed ancestral origin (n = 64). Grip strength was measured, and physical activity, housing density and dietary data were collected. Whole body BMC (WB BMC), fat-free soft tissue and fat tissue were measured using dual energy X-ray absorptiometry.

RESULTS

Maternal alcohol consumption during pregnancy was associated with WB BMC, however after adjusting for possible confounders, this was no longer significant. When combined with gender, gestational age and maternal BMC in a multiple regression, maternal alcohol consumption during pregnancy could explain 20% of the variance in the WB BMC, however when current height was included in the model, the contribution of the other factors was insignificant. There was however a significant correlation between current height and birth weight (r = 0.34; p < 0.01) and alcohol consumption during pregnancy (r = 0.34; p < 0.05). A model consisting of current factors such as age, weight, gender, grip strength and calcium intake was able to explain 81.5% of the variance. Housing density was negatively correlated with WB BMC (r =-0.11; p = 0.05).

CONCLUSION

These data suggest that although early life factors may contribute indirectly to the bone mass of children of mixed ancestral origin, the contribution of current factors is greater. In addition, environmental factors such as housing density have a direct effect on bone mass, independent of body size.

Factors associated with menstrual dysfunction and self-reported bone stress injuries in female runners in the ultra- and half-marathons of the Two Oceans

OBJECTIVE

To investigate factors associated with menstrual dysfunction, self-reported bone stress injuries and energy balance in women runners.

METHODS

613 runners were randomly sampled during the registration period for an endurance event. Demographic information, including self-reported height and weight, training and injury history and menstrual history, was collected by questionnaire.

RESULTS

Ultra-marathon (ULTRA) participants (n = 276) were significantly older (mean (SD) 39 (8.2) vs 34 (10.5) years; p<0.001), lighter (58.2 (6.6) vs 59.6 (8.3) kg; p<0.05) and reported a higher training volume (p<0.001) than half-marathon (HALF) participants (n = 337). Significantly more ULTRA subjects than HALF subjects reported a previous bone stress injury (21% vs 14%; p<0.05). There was no difference between the groups for menstrual status, but age at menarche was later (p<0.01) in the ULTRA group. Data were combined according to the absence (REG; n = 368/602 (61%)) or presence (IRREG; n = 234/602 (39%)) of a history of menstrual irregularity. Subject morphology was similar between groups, but the IRREG group had a higher self-reported measure on the self-loathing subscale (SLSS; p<0.01). The whole group was then classified according to current menstrual status, with 165 women being classified as currently irregular. (OLIGO/AMEN; 11.6%) and 445 women as currently regular (EUMEN; 88.4%). There were no morphological differences between the groups, however the OLIGO/AMEN group had a later age of menarche (p<0.01) than the EUMEN group. Further, women who reported a previous bone stress injury had higher SLSS scores than those who did not (2.91 (0.98) vs 2.68 (0.84); p<0.05).

CONCLUSIONS

There may be two independent mechanisms associated with energy balance, which are related to bone stress injuries, but may not necessarily be related to menstrual dysfunction.

An inventory of the South african fitness industry

Objective. The aim of this study was to create an inventory of fitness facilities in South Africa, their location, equipment and services offered, and the demographics, education and training of the staff working in these facilities. Design. A total of 750 facilities were identified, and descriptive data were gathered from 442 facilities (59%) with the use of a questionnaire administered telephonically and via the website of the Sports Science Institute of South Africa. Setting. The study was initiated by the Sports Science Institute, and the results were presented at the 4th Annual Discovery Vitality Fitness Convention on 4 May 2006. Results. Results show that the industry comprises mainly independent facilities (68%). All types of facilities were found to be located mostly within urban areas, and reported providing services to just less than 2% of the South African population. Facilities offer a wide range of equipment and services to their members. Of the fitness-related staff at facilities, the majority were reported to be young (18 - 25 years, 55% of male, and 49% of female staff), and in terms of racial proportions most staff were white (males 40% of total staff and females 33% of total staff).Less than a quarter of fitness-related staff hold university qualifications, and just over 80% of instructors hold qualifications aligned with the National Qualifications Framework. The importance of education and training of staff was emphasised by respondents. Conclusions. This report highlights the widespread value of assessing the fitness industry, particularly within the context of the rise of chronic diseases in South Africa and government initiatives to promote healthy lifestyles. South African Journal of Sports Medicine Vol. 18 (3) 2006: pp. 93-104

Lifestyle questionnaire to evaluate risk for reduced bone mineral density in women

OBJECTIVE

To determine the contribution of various risk factors to quantitative ultrasound parameters in a sample of women, and to develop a tool to assess osteopenia risk, with a view to targeted early intervention.

DESIGN

Questionnaire study.

SETTING

A local center comprising a fitness center, conference center, and administrative offices for various businesses and sports.

PATIENTS OR PARTICIPANTS

A convenience sample of 187 Caucasian women who volunteered as part of a free public health screening initiative.

MAIN OUTCOME MEASUREMENTS

A questionnaire was designed to collect data on history of osteoporosis, current physical activity, calcium, alcohol and caffeine intakes, smoking, and various reproductive measures. Historical physical activity data were also collected, and lifetime energy expenditure and impact scores were calculated. Quantitative ultrasound was performed on the left calcaneus. Odds ratios (ORs) were calculated to determine the odds of being osteopenic (T-score < or =-1 SD) against not being osteopenic (T-score >-1SD), due to exposure to the aforementioned risk factors.

RESULTS

: Significant ORs were obtained for age (OR: 1.042; 95% CI: 1.016-1.068), current physical activity (> or =3 times/wk; OR: 0.320; 95% CI: 0.140-0.732), and lifetime energy expenditure score (OR: 0.957; 95% CI: 0.926-0.989). A regression model based on age and current physical activity correctly identified 57% of women with or without osteopenia.

CONCLUSIONS

Although the model we developed was not sensitive or specific enough to assess osteopenic risk accurately, the results show that frequency of physical activity, independent of age, is an important lifestyle factor to consider when quantifying osteopenic risk.

Ultrasound bone measurements in pre-adolescent girls: interaction between ethnicity and lifestyle factors

AIM

We obtained calcaneal ultrasound measurements in 198 girls between 7.5 and 11.7 y of age, representing ethnic groups (black [n = 80], white [n = 41], mixed ancestral origin [n = 77]) in South Africa.

METHODS

Anthropometry was assessed. Demographics, physical activity, habitual dietary calcium intake and pubertal development were quantified by questionnaires. Broadband ultrasound attenuation (BUA) and speed of sound (SOS) of the left calcaneus were measured. Girls in Tanner breast stage 5 and/or those menstruating were excluded from analysis.

RESULTS

Black girls were lighter than white girls (31.4 +/- 7.8 vs 34.8 +/- 7.5 kg; p < 0.05), and shorter than girls of mixed ancestral origin (1.29 +/- 0.08 vs 1.34 +/- 0.07 m; p < 0.001) and white girls (1.35 +/- 0.07 m; p < 0.001), after adjusting for age. Reported calcium intake scores were higher in black than white girls (21.6 +/- 11.1 vs 16.1 +/- 8.4; p < 0.01). Total peak bone strain score (TPBSS) was higher in white compared to black girls (6.8 +/- 4.8 vs 5.0 +/- 4.7; p < 0.05), while walking energy expenditure (MET h/wk) was higher in black girls compared to the other groups (p < 0.001). BUA and SOS were higher in the black girls (59.6 +/- 13.7 dB/MHz; 1575.1 +/- 22.6 m/s; p < 0.001) and girls of mixed ancestral origin (59.0 +/- 12.5 dB/MHz; 1567.8 +/- 26.1 m/s; p < 0.01) than in the white girls (50.4 +/- 8.7 dB/MHz; 1552.1 +/- 19.5 m/s). Co-varying for age and weight did not affect these results. Walking energy expenditure (r = 0.20) and calcium score (r = 0.17) were correlated (p < 0.05) with SOS for the whole group.

CONCLUSION

Ultrasound parameters were lower in the white compared to the black girls, who consumed more calcium on average, but who were lighter, shorter and performed less impact activity. This suggests that interactions between ethnicity and lifestyle factors determine bone quality in premenarcheal girls.

Long-term restoration of deficits in bone mineral density is inadequate in premenopausal women with prior menstrual irregularity

OBJECTIVE

To investigate change in bone mineral density (BMD) in premenopausal women (age, 29-46 years), some of whom were marathon runners with a history of menstrual irregularity.

DESIGN

Longitudinal follow-up.

SETTING

University medical school.

PARTICIPANTS

We investigated 8 sedentary controls (SC) and 19 marathon runners (12 with regular menses (R) and 7 with a history of irregularity (OA) 11.7 +/- 7.9 years before follow-up).

MAIN OUTCOME MEASURES

BMD (g/cm2) of lumbar spine (LS) and proximal femur were determined at baseline and follow-up (3-5 years later). We calculated a menstrual history index (MHI) (estimated periods/year since age 13).

RESULTS

Body mass, age at menarche, and femoral BMD were not statistically different. Follow-up LS BMD (g/cm2) was lower (p < 0.01) in OA (0.936 +/- 0.060) than in R (1.043 +/- 0.103) and SC (1.094 +/- 0.077), even when covarying for age or both age and mass. No group changed BMD significantly with time. Current MHI was lower (p < 0.001) in OA (9.7 +/- 1.4) than in R (11.3 +/- 0.5) and SC (11.8 +/- 0.4). MHI for the teenage years was lower in OA than in SC but not in R. OA had significantly lower MHI than did R and SC for the third and fourth decades. Only MHI during the third decade correlated significantly with LS BMD for all subjects.

CONCLUSIONS

Restoration of LS BMD deficit in women with prior menstrual irregularity aged over 30 is slow and may never reach the same level as age-related controls; secondly, this may be the result of both bone loss in the third decade of life and reduced acquisition during adolescence.

Bone mineral density in mature, premenopausal ultramarathon runners

We measured bone mineral density (BMD) in 25 premenopausal ultramarathon (56 km) runners aged 29-39 yr and related risk factors for decreased BMD with actual BMD. Fifteen runners who had never had oligo/amenorrhea (R) were compared with 10 runners (OA): 4 oligomenorrheic, 2 amenorrheic, and 4 with prior oligo/amenorrhea. Menstrual, dietary and training data were obtained. BMD of the lumbar spine (LS) and proximal femur (F) were measured by dual energy x-ray densitometry. Both groups had similar body mass (58 +/- 8 vs 57 +/- 8 kg), running and dietary histories. F BMD was not different (P = 0.07) and correlated only with BMI (P < 0.05; r = 0.43). LS BMD was lower in OA (0.946 +/- 0.098 g.cm-2) than R (1.088 +/- 0.069 g.cm-2; P < 0.001). Menstrual History Index (MHI), (estimated periods.yr-1 since age 13), was higher in R (11.6 +/- 0.6) than OA (9.4 +/- 2.1; P < 0.01). LS BMD correlated with MHI (P < 0.0005; r = 0.67) and years oligomenorrheic (P < 0.01; r = -0.58) but not years amenorrheic, parity, breastfeeding, diet, or training. In conclusion, in mature women distance runners low LS BMD is related to a history of oligo/amenorrhea regardless of resumption of regular menstrual cycles in some subjects. Not only amenorrhea, but also prolonged oligomenorrhea may negatively influence peak adult bone mass.