Izabella A. Ludwa

Relative importance of body composition, osteoporosis-related behaviors, and parental income on bone speed of sound in adolescent females

IntroductionAdolescence provides a unique opportunity to employ strategies aimed at optimizing peak bone mass yet there are limited studies on the relationship between specific social constructs, osteoporosis-related behaviors, and bone health status in adolescent females. The purpose of this study was to examine associations between bone speed of sound (SOS) and body composition, osteoporosis-related health behaviors, and parental income in adolescent females.MethodsFour hundred forty-two female students in grades 9–12 from schools in Southern Ontario, Canada were measured for height, body mass, and percent body fat and completed a battery of instruments to assess osteoporosis-related health behaviors. Bone SOS was measured by transaxial quantitative ultrasound at the distal radius and midtibia.ResultsPercent body fat was a negative correlate of tibial SOS. No significant correlation was found between physical activity and bone SOS yet physical activity was negatively related to adiposity. Hierarchical regression showed that age and percent body fat were the most important predictors of the variance in tibial SOS scores, with calcium intake having a weaker, yet significant, relationship. Age was the only statistically significant predictor of radial SOS. Users of oral contraceptives had higher radial SOS when controlling for age. Higher parental income was not associated with bone SOS but positive associations between parental income, daily calcium intake, and weekly physical activity were noted.ConclusionsBone SOS is reduced in adolescent females with increased adiposity, whereas it is positively influenced by oral contraceptives and daily calcium intake.

Factors associated with bone turnover and speed of sound in early and late-pubertal females

This cross-sectional study examines whether maturity, body composition, physical activity, dietary intake, and hormonal concentrations are related to markers of bone turnover and tibial speed of sound (tSOS) in premenarcheal (n = 20, 10.1 ± 1.1 years) and postmenarcheal girls (n = 28, aged 15.0 ± 1.4 years). Somatic maturity was evaluated using years from age of peak height velocity (aPHV). Daily dietary intake was assessed with a 24-h recall interview, and moderate to very vigorous physical activity (MVPA) was measured using accelerometry. Plasma levels of 25-OH vitamin D, serum levels of insulin-like growth-factor 1 (IGF-1) and leptin, and serum levels of bone turnover markers including osteocalcin (OC), bone-specific alkaline phosphatase (BAP) and cross-linked N-teleopeptide of type I collagen (NTX) were measured using ELISA. OC, BAP, and NTX were significantly higher while IGF-1 and tSOS were lower in the premenarcheal group. The premenarcheal girls were more active and had higher daily energy intake relative to their body mass but there were no group differences in body mass index percentile. Maturity predicted 40%-57% of the variance in bone turnover markers. Additionally, daily energy intake was a significant predictor of OC, especially in the postmenarcheal group. IGF-1 and MVPA were significant predictors of BAP in the group as a whole. However, examined separately, IGF-1 was a predictor of BAP in the premenarcheal group while MVPA was a predictor in the postmenarcheal group. Adiposity and leptin were both negative predictors of tSOS, with leptin being specifically predictive in the postmenarcheal group. In conclusion, while maturity was the strongest predictor of bone markers and tSOS, dietary intake, physical activity, body composition, and hormonal factors further contribute to the variance in bone turnover and bone SOS in young Caucasian females. Further, the predicting factors of bone turnover and tSOS were different within each maturity group.

Correlates of Mucosal Immunity and Upper Respiratory Tract Infections in Girls

ABSTRACT In this study we examined whether salivary hormones, physical activity and adiposity were correlated with secretory immunoglobulin A (sIgA) and frequency of upper respiratory tract infections (URTI) in 43 early-pubertal and 59 late-pubertal girls. Physical activity was measured using accelerometers and relative body fat was assessed using bioelectrical impendence. Resting saliva samples were obtained between 1500 and 1800hr and assayed for sIgA, cortisol and testosterone. Participants completed a one-month health log to record URTI frequency. Early-pubertal girls were more physically active, had less adiposity, but lower concentrations of sIgA than late-pubertal adolescents (122.7±91.6 vs 201.9±102.9 pg/ml, respectively). The frequency of URTI was similar in the two groups. Neither sIgA nor URTI were correlated with salivary hormones, physical activity or adiposity within the early-pubertal girls. In the late-pubertal group, sIgA was negatively associated (r=-0.44; p≤0.05) with cortisol, and positively associated (r=0.41; p≤0.05) with the testosterone to cortisol ratio. These results suggest that mucosal immunity increases with pubertal maturation, while higher cortisol is associated with lower mucosal immunity in adolescents.

Quantitative bone ultrasound measurements in young females 14-23 years of age.

AIM This study examined how transaxial quantitative ultrasound (QUS) measurements differed in young females between 14 and 23 years of age and if body composition and behavioral factors, namely, oral contraceptive (OC) use, physical activity, and calcium intake, influenced these measurements. METHODS Participants (n = 595) were classified as nonusers or users of OC. QUS measurements were performed at the distal radius and midtibia, and the bone speed of sound (SOS) was recorded for each site. Body mass index (BMI) was calculated from body mass and height. Physical activity and dietary calcium intake were assessed using standardized questionnaires. RESULTS Bone SOS increased significantly with increasing age (r(2) = 0.28 and 0.20 for radius and tibia, respectively, p < 0.05) but slower after age 18. OC use was not significantly associated with the QUS measurements, yet there was a significant age-by-OC use interaction (p < 0.05) for SOS of the tibia. For the nonusers of OC, age, BMI, and calcium intake were significant predictors of tibia SOS, explaining 24% of the variance in tibial SOS scores, whereas among the OC users, only age and BMI were significant predictors of tibial SOS, explaining 18% of the variance with no other variables entering in the model. Age was the only predictor of radius SOS in both groups. QUS scores increased steadily from 14 to 23 years of age in young females. CONCLUSIONS OC use was associated with lower tibial SOS scores in early adulthood but not during adolescence, suggesting that OC use possibly may interfere with the bone development of the tibia. Furthermore, daily calcium intake demonstrated a positive relationship with the tibial SOS only in the nonusers of OC; however, this relationship was reversed for BMI irrespective of OC use.

The effect of adiposity on the relationship between indicators of maturity in peri-pubertal children

Background: Although the relation between body fatness and maturation has been the subject of much research, somatic maturity as assessed by sex-specific regression equations, has yet to be investigated in a population of overweight and obese children. Aim: To examine whether adiposity affects the relationship between somatic and skeletal maturity in peri-pubertal children and if increased adiposity is related to earlier maturation. Subjects and methods: A total of 172 girls and boys (12.8 ± 0.9 years of age) participated in the study. Participants were categorized as normal weight (NW, < 85th percentile) or overweight/obese (OW/OB, ≥ 85th percentile) based on body mass index and matched for chronological and skeletal age. Skeletal age was assessed across the radial and ulnar epiphyses using quantitative ultrasound. Somatic maturity was assessed as years from age of peak height velocity (aPHV), estimated using prediction equations. Peripheral adiposity was determined by the sum of two skin-folds. Results: Years from aPHV was significantly higher (p < 0.001) in OW/OB girls, but not in OW/OB boys. Skeletal age was associated with years from aPHV in NW and OW/OB boys (r = 0.87 vs 0.86, p < 0.001) and girls (r = 0.83 vs 0.72, p < 0.001). Among peri-pubertal youth of similar chronological and skeletal age, OW/OB girls were more somatically mature than their NW peers. Conclusion: It is concluded that excess peripheral adiposity in girls may affect the estimated somatic maturity, as reflected in years from aPHV.

Physical Activity Interactions with Bone Accrual in Children and Adolescents

1.1 Osteoporosis and peak bone mass Osteoporosis is a skeletal disease characterized by low bone mass and the deterioration of the micro architecture of bone tissue resulting in bone fragility and susceptibility to fractures (Gordon, 2003). According to the World Health Organization, osteoporosis is estimated to affect approximately 200 million women worldwide (Kanis, 2007) with the burden of osteoporosis being felt both personally and economically. Although the prevalence of fractures is higher is women, the mortality rate related to fragility fractures is higher in men (Center et al. 1999; Hasserius et al., 2003). Moreover, the annual cost of treating fractures in the United States is projected to increase to

Mechanical, Biochemical and Dietary Determinants of the Functional Model of Bone Development of the Radius in Children and Adolescents

25 billion in 2025 from

Bone Speed of Sound and Physical Activity Levels of Overweight and Normal-Weight Girls and Adolescents

17 billion in 2005 (Burge et al., 2005). Achieving peak bone mass (PBM) during adolescence and the subsequent rate of bone loss are major determinants of bone mass later in life (Hansen et al., 1991). The amount of bone mass achieved early in life has been shown to predict the level of bone mass and the incidence of fracture later in life suggesting that a primary risk factor for the development of osteoporosis is the inability to attain high PBM (Hansen et al., 1991; Heaney et al., 2000). PBM is generally defined as the highest level of bone mass achieved as a result of normal growth and seems to be established, for most sites of the skeleton, by late adolescence (Matkovic et al., 1994). Previous studies (Bonjour et al., 1991; Bailey et al., 1996) have demonstrated the period between 9-20 years of age to be critical in building peak bone mass as 90% of total body bone mineral content (BMC) is accrued by the age of 16 (Elgan et al., 2003; Stager et al., 2006), with the remaining 5-10% of total body bone mass achieved in the third decade (Cadogan et al, 1998). In fact, the most rapid bone mineral accumulation occurs approximately 1 year after the age of peak linear growth (Bailey et al., 1996); around the time of menarche for females (Cadogan et al., 1998). With considerable increases in bone mass occurring during puberty, maximizing PBM during this time is often advocated as the best way to delay age-related bone loss and prevent osteoporotic fractures (Fulkerson et al., 2004; Molgaard et al., 1999; Valimaki et al., 1994). It appears, therefore, as though there is a critical period, a ‘window of opportunity’ (MacKelvie et al., 2002), in which we can influence the amount of bone mass we attain. However, bone development is the product of complex interactions between genetic and environmental factors including diet, hormonal influences, and mechanical stimuli (Gordon, 2003; Steelman & Zeitler, 2001). Permanent deficits in PBM are the result of any process that

Bone Speed of Sound, Bone Turnover and IGF-I in Adolescent Synchronized Swimmers

This study examined the degree to which various mechanical, biochemical, and dietary factors are related to nonweight bearing bone properties in 172 healthy peri-pubertal children (age, 11.7 ± 2.0 years). Dominant radial speed of sound (rSOS) was measured by transaxial quantitative ultrasound at distal radius. Potential modulating factors included somatic maturity offset (years from age of peak height velocity), grip strength, forearm lean cross-sectional area (CSA), physical activity, nutritional intake, and amino-terminal cross-linking propeptide (NTx), reflecting bone resorption. In a hierarchical regression, grip strength adjusted for CSA was the second most important predictor of rSOS after the maturity offset (β = 0.22 and β = 0.33, respectively; R2 = 0.16). When relative grip strength was added to the model the contribution of sex was no longer significant. Calcium intake was a significant predictor of rSOS only after NTx was accounted for in the model (β = 0.17, R2 = 0.21). This may suggest that calciums effects on the muscle-bone unit may be modulated through bone resorption. In the final model, relative grip strength together with maturity offset, dietary calcium, and NTx explained up to 21% of the variance in rSOS in this cohort of children. Therefore, during the peri-pubertal stage, size-adjusted forearm muscle strength is related to radial bone strength after controlling for maturity, with calcium intake having a potential indirect association through NTx.