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Biomedical subjects

Keith J Loud

Publications and source records attributed to Keith J Loud.

5 recordsLinked to original sources
PubMed2006

Effects of nutrition, puberty, and gender on bone ultrasound measurements in adolescents and young adults.

PURPOSE: Quantitative ultrasound (QUS) evaluation of bone is attractive for evaluating skeletal status in adolescents, but its use is limited in the United States due to sparse pediatric reference data. This study evaluated associations between radial and tibial speed of sound (SOS) measurements via QUS and demographic, anthropometric and nutritional variables. METHODS: We enrolled 151 healthy participants, aged 11-26 years, during routine visits to an urban adolescent clinic. SOS measurements were obtained using the Omnisense 7000P (Sunlight Medical Ltd., Tel-Aviv, Israel) and correlated with weight, height, gender, race, sexual maturity rating (SMR), and reported nutritional intake. RESULTS: The sample was 53% female; aged 17+/- 2.8 years (mean +/- SD); and 48% African-American, 21% Hispanic, and 21% Caucasian. Seventy percent of males and 91% of females had achieved SMR 5; 96% of females were postmenarchal. Males met the recommended daily allowance for calcium intake, on average; the females did not. Both the girls and boys reported consumption of inadequate vitamin D. Intake of neither calcium nor vitamin D was correlated with SOS. Radial and tibial SOS were significantly higher in those with SMR 5 (p < .001) and were moderately correlated with age in both genders (r = .42-.64, p < .001). In multivariate analyses, age was associated with SOS at both sites (p < .0001). CONCLUSIONS: This study provides QUS measurements of the peripheral skeleton among healthy adolescents. QUS measurements followed similar age and pubertal distributions to dual-energy X-ray absorptiometry (DXA) bone density measurements; other variables did not follow expected trends. Further research is needed to clarify what skeletal properties are assessed by this technique. This study adds to accumulating evidence that many adolescents do not consume adequate vitamin D or calcium.

Adolescent↗
PubMed2006

Adolescent bone health.

Pediatric and adolescent care professionals have increasingly recognized the importance of understanding the skeletal health of their patients. Peak bone mass, the "bone bank" on which an individual will draw for their entire adult life, is likely achieved by late adolescence, with the critical window for accumulation occurring much earlier. This review outlines the known conditions that are associated with impaired bone mineral accrual and clinical settings in which the evaluation of "at-risk" adolescents should be considered. We describe the methods available to the health care professional for evaluating bone density, along with the limitations of each technology. Potential therapeutic options for patients identified to have a low bone mineral density are discussed. Finally, current recommendations regarding physical activity and nutrition, beneficial interventions for all adolescents, are presented.

Absorptiometry, Photon↗
PubMed2005

Correlates of stress fractures among preadolescent and adolescent girls.

OBJECTIVE: Although stress fractures are a source of significant morbidity in active populations, particularly among young female athletes, the causes of stress fractures have not been explored among females <17 years of age or in the general population. The purpose of this study was to examine correlates of stress fractures in a large, population-based, national, cohort study of preadolescent and adolescent girls. METHODS: A cross-sectional analysis of data from 5461 girls, 11 to 17 years of age, in the Growing Up Today Study, an ongoing longitudinal study of the children of registered female nurses participating in Nurses' Health Study II, was performed. Mothers self-reported information regarding their children's histories of stress fractures on their 1998 annual questionnaire. Growing Up Today Study participants self-reported their weight and height, menarcheal status, physical activity, dietary intake, and disordered eating habits on annual surveys. RESULTS: In 1998, the mean age of the participants was 13.9 years. Approximately 2.7% of the girls had a history of stress fracture, 3% engaged in disordered eating (using fasting, diet pills, laxatives, or vomiting to control weight), and 16% participated in > or =16 hours per week of moderate to vigorous activity. Age at menarche, z score of BMI in 1998, calcium intake, vitamin D intake, and daily dairy intake were all unrelated to stress fractures after controlling for age. Independent of age and BMI, girls who participated in > or =16 hours per week of activity in 1998 had 1.88 greater odds of a history of stress fracture than did girls who participated in <4 hours per week (95% confidence interval [CI]: 1.18-3.30). Girls who participated in > or =16 hours per week of activity were also more likely than their peers to engage in disordered eating (4.6% vs 2.8%); however, disordered eating did not have an independent association with stress fractures (odds ratio [OR]: 1.33; 95% CI: 0.61-2.89). Independent of age and BMI, each hour per week of high-impact activity significantly increased the risk of stress fracture (OR: 1.05; 95% CI: 1.02-1.09). Among the high-impact physical activities, only running (OR: 1.13; 95% CI: 1.05-1.22) and cheerleading/gymnastics (OR: 1.10; 95% CI: 1.01-1.21) were independently associated with greater odds of stress fracture. CONCLUSIONS: These findings suggest that, although activity can be beneficial for bone health, there is a threshold over which the risk of stress fracture increases significantly among adolescent girls. High-impact activities, particularly running, cheerleading, and gymnastics, appear to be higher risk than other activities. Prospective studies are needed to explore the directionality of these relationships, as well as the role of menstrual history. In the meantime, clinicians should remain vigilant in identifying and treating disordered eating and menstrual irregularities among their highly active, young, female patients.

Adolescent↗
PubMed2005

Exposure to the mass media, body shape concerns, and use of supplements to improve weight and shape among male and female adolescents.

OBJECTIVE: To assess the prevalence and correlates of products used to improve weight and shape among male and female adolescents. METHODS: A cross-sectional study was conducted of 6212 girls and 4237 boys who were 12 to 18 years of age and enrolled in the ongoing Growing Up Today Study. The outcome measure was at least weekly use of any of the following products to improve appearance, muscle mass, or strength: protein powder or shakes, creatine, amino acids/hydroxy methylbutyrate (HMB), dehydroepiandrosterone, growth hormone, or anabolic/injectable steroids. RESULTS: Approximately 4.7% of the boys and 1.6% of the girls used protein powder or shakes, creatine, amino acids/HMB, dehydroepiandrosterone, growth hormone, or anabolic/injectable steroids at least weekly to improve appearance or strength. In multivariate models, boys and girls who thought a lot about wanting more defined muscles (boys: odds ratio [OR]: 1.6; 95% confidence interval [CI]: 1.1-2.2; girls: OR: 2.3; 95% CI: 1.2-3.2) or were trying to gain weight (boys: OR: 3.0; 95% CI: 2.0-4.6; girls: OR: 4.3; 95% CI: 1.6-11.4) were more likely than their peers to use these products. In addition, boys who read men's, fashion, or health/fitness magazines (OR: 2.3; 95% CI: 1.1-4.9) and girls who were trying to look like women in the media (OR: 2.9; 95% CI: 1.4-4.0) were significantly more likely than their peers to use products to improve appearance or strength, but hours per week watching television, watching sports on television, and participation in team sports were not independently associated with using products to improve appearance or muscle mass. CONCLUSIONS: Girls and boys who frequently thought about wanting toned or well-defined muscles were at increased risk for using potentially unhealthful products to enhance their physique. These results suggest that just as girls may resort to unhealthful means to achieve a low body weight, girls and boys may also resort to unhealthful means to achieve other desired physiques.

Adolescent↗