Biomedical subjects

Sharon M Nickols-Richardson

Publications and source records attributed to Sharon M Nickols-Richardson.

9 recordsLinked to original sources

PubMed2006

Eating restraint is negatively associated with biomarkers of bone turnover but not measurements of bone mineral density in young women.

Relationships among bone mineral density (BMD), bone turnover markers, cortisol, calcium and vitamin D intakes, and cognitive eating restraint score were examined. Sixty-five healthy women, ages 18 to 25 years, had total body, spine, hip, and forearm BMD measured by dual-energy x-ray absorptiometry. Serum osteocalcin, urinary cross-linked N-telopeptide of type I collagen (NTx), and salivary cortisol were measured, and intakes of calcium and vitamin D were estimated from questionnaires. Cognitive eating restraint scores were determined from the Eating Inventory. Associations between measures were analyzed by Pearson correlations; predictors of BMD and bone turnover markers were tested using stepwise regression. Serum osteocalcin (P<0.01) and urinary NTx (P<0.05) were negatively related to cognitive eating restraint score. Intakes of calcium (P<0.05) and vitamin D (P<0.05) were associated with forearm BMD. Regression analyses indicated that vitamin D intake predicted total body (P<0.08) and forearm (P<0.01) BMD. Negative associations between cognitive eating restraint score and bone biomarkers suggest a reduction in bone remodeling, not reflected in current BMD.

Absorptiometry, Photon↗

PubMed2006

Knee extensor and flexor torque development with concentric and eccentric isokinetic training.

This study assessed muscular torque and rate of torque development following concentric (CON) or eccentric (ECC) isokinetic training. Thirty-eight women were randomly assigned to either CON or ECC training groups. Training consisted of knee extension and flexion of the nondominant leg three times per week for 20 weeks (SD = 1). Eccentric training increased ECC knee extension and flexion peak torque more than CON training. The ECC group improved acceleration time and time to peak torque with ECC movements versus the CON group. Slow-velocity ECC isokinetic training yielded greater ECC and similar CON torque development gains versus CON training over the course of 20 weeks in young women.

Adolescent↗

PubMed2006

Hypertension research in sleep apnea.

Obstructive sleep apnea (OSA) is characterized by repetitive partial and total collapse of the upper airway that induces stressful arousals throughout sleep to reestablish breathing. Although estimates vary, prevalence has been reported as high as 20% in the adult population. OSA is common in several chronic diseases, the most common of which is obesity. Evidence is strong that OSA increases the risk of hypertension and both fatal and nonfatal cardiovascular events. Several mechanisms linking OSA to hypertension have been proposed, with increased sympathetic activation implicated as the prime mediator. This review summarizes recent data on the influence of OSA on blood pressure, the effect of standard OSA therapy on improving blood pressure, and the potential of lifestyle modification for further decreasing hypertension risk. Challenges confronting the investigation of blood pressure outcomes in response to treatment in OSA patients are discussed.

Blood Pressure↗

PubMed2005

Urinary ketones reflect serum ketone concentration but do not relate to weight loss in overweight premenopausal women following a low-carbohydrate/high-protein diet.

This study examined the effect of a low-carbohydrate/high-protein diet on serum and urine ketone body concentrations. Thirteen overweight premenopausal women aged 32 to 45 years consumed < or =20 g carbohydrate/day with liberal intakes of protein and fat for 2 weeks; thereafter, carbohydrate intake increased 5 g/week for 10 weeks. Women were weighed and provided fasting urine and blood samples to detect urinary ketones and quantify serum ketone concentrations, respectively, at baseline and weeks 1 to 4, 6, and 12. Women lost 8.3%+/-2.8% of initial body weight by week 12. Serum beta-hydroxybutyrate production was highest at week 1 and declined weekly, with all values higher than baseline (P <.05). Each week, serum beta-hydroxybutyrate was correlated with presence of urinary ketones (P <.05), but no relationship was found between weekly weight change and serum ketone production. Urinary ketones are detected in premenopausal women complying with a low-carbohydrate/high-protein diet and are associated with serum ketone concentration. However, serum ketones do not reflect weight loss.

3-Hydroxybutyric Acid↗

PubMed2005

Perceived hunger is lower and weight loss is greater in overweight premenopausal women consuming a low-carbohydrate/high-protein vs high-carbohydrate/low-fat diet.

The impact of a low-carbohydrate/high-protein diet compared with a high-carbohydrate/low-fat diet on ratings of hunger and cognitive eating restraint were examined. Overweight premenopausal women consumed a low-carbohydrate/high-protein (n=13) or high-carbohydrate/low-fat diet (n=15) for 6 weeks. Fasting body weight (BW) was measured and the Eating Inventory was completed at baseline, weeks 1 to 4, and week 6. All women experienced a reduction in BW (P<.01), although relative BW loss was greater in the low-carbohydrate/high-protein vs high-carbohydrate/low-fat group at week 6 (P<.05). Based on Eating Inventory scores, self-rated hunger decreased (P<.03) in women in the low-carbohydrate/high-protein but not in the high-carbohydrate/low-fat group from baseline to week 6. In both groups, self-rated cognitive eating restraint increased (P<.01) from baseline to week 1 and remained constant to week 6. Both diet groups reported increased cognitive eating restraint, facilitating short-term weight loss; however, the decrease in hunger perception in the low-carbohydrate/high-protein group may have contributed to a greater percentage of BW loss.

Adult↗

PubMed2005

Distal tibia areal bone mineral density: use in detecting low aBMD of the hip in young women.

Dual-energy X-ray absorptiometry (DXA) is a primary clinical tool for identification of adults with low areal bone mineral density (aBMD) and who are at increased risk for future osteoporosis and fragility fractures. Procedures for several aBMD scans of clinical interest might be limited by artifact, inaccessible anatomical regions, and positioning errors. Sites for scanning that overcome these limitations need further investigation for application to large-scale screening and relevance to clinical decisions regarding diagnosis and treatment. In this study, 146 women (mean +/- SE age = 20.1 +/- 0.1 yr, height = 163.3 +/- 0.2 cm, weight = 60.0 +/- 0.2 kg) underwent DXA of the total body (TB) and right and left total proximal femurs (TPF), total forearms (TF), and distal tibiae (DT). Osteopenia was identified in 24 women. Areal BMD was positively related among all measurement sites (r = 0.55-0.81, all p < 0.001). Total body, TF, and DT aBMD each displayed low sensitivity (0.29-0.33) and high specificity (0.95-0.98) to detect osteopenia of the TPF. Addition of TB fat-free mass slightly enhanced the predictive value of DT aBMD. Overall, DT aBMD can discriminate between osteopenic and normal subjects with comparable accuracy to TB or TF aBMD.

Absorptiometry, Photon↗

PubMed2004

Cognitive eating restraint scores are associated with body fatness but not with other measures of dieting in women.

Nearly 50% of women report dieting to lose weight, but the ability of cognitive eating restraint (CER) scores to separate women based on indicators of restricted intake has not been adequately demonstrated. We examined the ability of the CER subscale of the eating inventory to distinguish differences in resting energy expenditure (REE), body composition, cortisol, dietary intake, and physical activity, in a group of women. Subjects (20.4+/-2.3 years) were divided into high (score>9; n=31) and low (score< or =9; n=34) CER groups based on questionnaire responses. Indirect calorimetry was used to measure REE and dual-energy X-ray absorptiometry to measure body composition. Salivary and 24-hour urinary cortisol were measured by bioassays. Food frequency questionnaires and 4-day food records, physical activity recalls, and anthropometric measures were completed. Women in the high CER group possessed more fat mass (p<0.05) and higher body fat percent (p<0.05) and consumed more servings of fruits and vegetables per day (p<0.05) compared to women in the low CER group. Differences in other indicators were not observed between CER groups. Our findings suggest that cognitive restraint and body fatness may not be independent of one another.

Absorptiometry, Photon↗

PubMed2004

Effect of post-exercise supplement consumption on adaptations to resistance training.

OBJECTIVE: Athletes are interested in nutritional manipulations that may enhance lean tissue gains stimulated by resistance training. Some research demonstrates that acute consumption of food containing protein causes superior muscle protein synthesis compared to isoenergetic foods without protein. This benefit has not been verified in longer-term training studies. We compared body composition and muscle function responses to resistance training in males who consumed a carbohydrate or a multi-macronutrient beverage following each training session. METHODS: Nineteen, untrained men (18-25 years) consumed either a milk (MILK) or a carbohydrate-electrolyte (CHO) drink immediately following each workout during a 10 week resistance training program. Muscle strength (1RM for seven exercises), body composition (DXA scan), fasted, resting concentrations of serum total and free testosterone, cortisol, IGF-1, and resting energy expenditure (REE) were measured prior to and at the end of training. RESULTS: Resistance training caused an increase (44 +/- 4%, p < 0.001) in muscular strength for all subjects. The training program reduced percent body fat (8%, p < 0.05, -0.9 +/- 0.5 kg) and increased fat-free soft tissue (FFST) mass (2%, 1.2 +/- 0.3 kg, p < 0.01). MILK tended to increase body weight and FFST mass (p = 0.10 and p = 0.13, respectively) compared to CHO. Resting total and free testosterone concentrations decreased from baseline values in all subjects (16.7%, 11%, respectively, p < 0.05). Significant changes in fasting IGF-1, cortisol, and REE across training were not observed for either group. CONCLUSION: Post-resistance exercise consumption of MILK and CHO caused similar adaptations to resistance training. It is possible that a more prolonged training with supplementation period would expand the trend for greater FFST gains in MILK.

Adaptation, Physiological↗

PubMed2002

A prospective study of bone mass and body composition in female adolescent gymnasts.

OBJECTIVE: To examine changes in bone and body composition of adolescent female artistic gymnasts (GYM; n = 7), level 5+, compared with nongymnast controls (CON; n = 10) over 3 years. STUDY DESIGN: Areal bone mineral density (aBMD; g/cm(2)), bone mineral content (BMC; g) and bone area (cm(2)), of the total body (TB), total proximal femur (TPF), trochanter (Tr), femoral neck, lumbar spine (LS), and distal radius were measured using dual-energy X-ray absorptiometry. Fat-free soft tissue mass (FFST; g), fat mass (g), and percent body fat (%FAT) were also assessed. RESULTS: No initial differences in height or weight between GYM and CON were observed, and both groups demonstrated parallel increases in these parameters over time (P <.05; h(2) >or=0.15). At baseline, GYM possessed significantly lower %FAT and higher aBMD at all sites (except TB; P <.05; h(2) >or=0.15). Over 3 years, GYM increased more than CON (P <.05; eta (2) >or=0.15) in TB, Tr, and TPF aBMD, TB and LS BMC, and FFST. CONCLUSION: Female adolescents participating in competitive artistic gymnastics training over 3 years have enhanced rates of aBMD, BMC and FFST accrual.

Adolescent↗