Bogus concerns about the false prototype enhancement effect.

Two experiments addressed the mechanism responsible for the false prototype effect, the phenomenon in which a prototype gradient can be obtained in the absence of learning. Previous demonstrations of this effect have occurred solely in a single-category paradigm in which transfer patterns are assigned or not to the learning category. We tested the hypothesis that any extraneous variable potentially responsible for this effect, such as compactness varying with pattern distortion (Zaki & Nosofsky, 2004), may be functional in the single-category paradigm but not when multiple categories are available at the time of transfer. In the present study, subjects received a bogus or a real category learning phase, followed by a transfer test that required assignment into 1 or 3 prototype categories. The results showed that a minimal prototype gradient was obtained in the bogus conditions, with performance approaching chance levels when classification into 3 categories was required. In contrast, a substantial prototype gradient effect was found following learning. We conclude that the prototype gradient typically obtained following multiple-category learning is primarily driven by real learning and that the false prototype effect is itself an artifact of the single-category paradigm.

Correlates of upper and lower body muscular strength in children.

Despite the widespread use of and acceptance of muscular fitness field tests in national youth fitness test batteries, little is known about how these field tests compare to 1 repetition maximum (1RM) strength in children. Therefore, the aim of this study was to characterize and identify correlates of muscular strength in children 7 to 12 years of age. Ninety children (39 girls and 51 boys) between the ages of 6.7 and 12.3 years volunteered to participate in this study. Children were tested on 1RM chest press (CP) strength, 1RM leg press (LP) strength, handgrip strength, vertical jump, long jump, sit and reach flexibility, and height and weight (used to determine body mass index [BMI]). For the combined sample, LP 1RM ranged from 75% to 363% of body weight and CP 1RM ranged from 25% to 103% of body weight. Multiple regression analyses predicting LP 1RM showed that BMI and long jump were significant (R = 44.4% with age and gender not significant) and BMI and vertical jump were significant (R = 40.8% with age and gender not significant). Multiple regression analyses predicting CP 1RM showed that BMI and handgrip strength were significant (R = 58.6% with age and gender not significant). Age and gender alone accounted for 4.6% (not significant) of the variation in LP 1RM and 15.4% (significant) in CP 1RM. In summary, these data indicate that BMI, handgrip strength, long jump, and vertical jump relate to 1RM strength in children and therefore may be useful for assessing muscular fitness in youths.

Depressive symptoms and changes in body weight exert independent and site-specific effects on bone in postmenopausal women exercising for 1 year.

BACKGROUND: Lower bone mineral density (BMD) has been documented in clinically depressed populations, and depression is the second most common chronic medical condition in general medical practice. Therefore, the purpose of this study was to determine whether depressive symptoms, vitality, and body weight changes were related to 1-year BMD changes after accounting for covariates. METHODS: Healthy postmenopausal women (n=320; 40-65 years) were recruited, and 266 women completed the study. Participants were 3-10 years postmenopausal, sedentary, and either taking hormone replacement therapy (1-3.9 years) or not taking it (at least 1 year). Exclusion criteria were: current smoking status, history of fractures, low BMD, body mass index>32.9 or <19.0, or use of bone altering medications. Regional BMD was measured from dual-energy x-ray absorptiometry at baseline and 1 year. Self-reported depressive symptoms and vitality were measured using standard questionnaires. RESULTS: Both the vitality and depressive symptoms scores were related to BMD changes at the femur neck but not at the greater trochanter or spine. Weight change was a predictor of BMD changes in the trochanter and spine but not in the femoral neck. Weight change and vitality and/or depressive symptoms had differential and site-specific effects on BMD changes at the hip. Vitality and depressive symptoms related to femoral neck changes and weight change related to greater trochanter changes. CONCLUSIONS: The negative impact of depressive symptoms on BMD in this population of postmenopausal women was independent of body weight or other behavioral factors such as calcium compliance or exercise.

Effects of exercise on bone mineral density in calcium-replete postmenopausal women with and without hormone replacement therapy.

Osteoporosis is a major public health concern. The combination of exercise, hormone replacement therapy, and calcium supplementation may have added benefits for improving bone mineral density compared to a single intervention. To test this notion, 320 healthy, non-smoking postmenopausal women, who did or did not use hormone replacement therapy (HRT), were randomized within groups to exercise or no exercise and followed for 12 months. All women received 800 mg calcium citrate supplements daily. Women who exercised performed supervised aerobic, weight-bearing and weight-lifting exercise, three times per week in community-based exercise facilities. Regional bone mineral density (BMD) was assessed by dual energy X-ray absorptiometry. Women who used HRT, calcium, and exercised increased femoral neck, trochanteric and lumbar spine bone mineral density by approximately 1-2%. Trochanteric BMD was also significantly increased by approximately 1.0% in women who exercised and used calcium without HRT compared to a negligible change in women who used HRT and did not exercise. The results demonstrate that regional BMD can be improved with aerobic, weight-bearing activity combined with weight lifting at clinically relevant sites in postmenopausal women. The response was significant at more sites in women who used HRT, suggesting a greater benefit with hormone replacement and exercise compared to HRT alone.

Cholesteryl ester transfer protein and lecithin:cholesterol acyltransferase activities in hispanic and anglo postmenopausal women: associations with total and regional body fat.

Reverse cholesterol transport is one process by which high-density lipoprotein (HDL) cholesterol has been hypothesized to play a role in reducing the risk of coronary heart disease. This study was designed to examine cholesteryl ester transfer protein (CETP) and lecithin:cholesterol acyltransferase (LCAT) activities, 2 modulators of reverse cholesterol transport, in Hispanic and Anglo postmenopausal women. The associations between plasma CETP and LCAT activities and body composition were also examined. Of the 199 subjects, 33% were of Hispanic origin and 47% were undergoing hormone replacement therapy (HRT). Body composition was measured by dual-energy x-ray absorptiometry (DXA) and anthropometry. Plasma CETP activity was higher in Hispanic compared to Anglo women, although the difference was eliminated when data were adjusted for abdominal fat. Hispanic women had lower plasma HDL cholesterol concentrations, higher total cholesterol:HDL cholesterol ratios and triglyceride concentrations, and greater susceptibility of low-density lipoprotein (LDL) particles to oxidation. Hispanic women also had a significantly greater relative deposition of body fat on the trunk and intra-abdominally than did Anglo women, even after adjusting for total body fat. There were no significant ethnic differences in LCAT activity. Plasma CETP and LCAT activities were negatively correlated with HDL cholesterol and positively correlated with total cholesterol, LDL cholesterol, and triglycerides, as well as total and regional body composition variables. In conclusion, results suggest a greater risk for coronary heart disease in Hispanic women compared to Anglo women.

Effects of exercise training and hormone replacement therapy on lean and fat mass in postmenopausal women.

BACKGROUND: Menopause is associated with decreases in lean mass and increases in fat mass. Serum hormone levels and hormone replacement therapy (HRT) may modify the effects of exercise training on body composition in postmenopausal women. METHODS: We assessed the changes in total body and regional lean soft tissue and fat mass (using dual-energy x-ray absorptiometry) in 94 sedentary postmenopausal women, aged 40-65 years, after 12 months of resistance and weight-bearing aerobic exercise training. Women currently on oral HRT (n = 39) and not on HRT (n = 55) were randomized within groups to exercise and no exercise, resulting in four groups: exercise + HRT (n = 20), HRT (n = 22), exercise (n = 24), and control (n = 28). Fasting blood samples were measured for resting serum total levels of estrone, estradiol, cortisol, androstenedione, growth hormone, and insulin-like growth factor 1 at baseline and 12 months. RESULTS: We found significant effects of exercise on increases in total body, arm, and leg lean soft tissue mass, and decreases in leg fat mass and percentage of body fat. There were no interaction effects of exercise and HRT on the changes in muscle strength and body composition. No significant changes in total hormone levels were found after 12 months. CONCLUSIONS: Exercise training resulted in significant beneficial changes in lean soft tissue and fat mass in early postmenopausal women. These changes in body composition were neither influenced by prolonged HRT use nor accompanied by changes in total levels of the hormones determined in this study.

Assessing the validity of body mass index standards in early postmenopausal women.

OBJECTIVE: To examine the relationship between percentage of total body fat (%Fat) and body mass index (BMI) in early postmenopausal women and to evaluate the validity of the BMI standards for obesity established by the NIH. RESEARCH METHODS AND PROCEDURES: Three hundred seventeen healthy, sedentary, postmenopausal women (ages, 40 to 66 years; BMI, 18 to 35 kg/m(2); 3 to 10 years postmenopausal) participated in the study. Height, weight, BMI, and %Fat, as assessed by DXA, were measured. Receiver operating characteristic analysis was performed to evaluate the ability of BMI to discriminate obesity from non-obesity using 38%Fat as the criterion value. RESULTS: A moderately high relationship was observed between BMI and %Fat (r = 0.81; y = 1.41x + 2.65) with a SE of estimate of 3.9%. Eighty-one percent of other studies examined fell within 1 SE of estimate as derived from our study. Receiver operating characteristic analysis showed that BMI is a good diagnostic test for obesity. The cutoff for BMI corresponding to the criterion value of 38%Fat that maximized the sum of the sensitivity and specificity was 24.9 kg/m(2). The true-positive (sensitivity) and false-positive (1--specificity) rates were 84.4% and 14.6%, respectively. The area under the curve estimate for BMI was 0.914. DISCUSSION: There is a strong association between %Fat and BMI in postmenopausal women. Current NIH BMI-based classifications for obesity may be misleading based on currently proposed %Fat standards. BMI >25 kg/m(2) rather than BMI >30 kg/m(2) may be superior for diagnosing obesity in postmenopausal women.

Body composition modulates the effects of hormone replacement therapy on growth hormone and insulin-like growth factor-I levels in postmenopausal women.

OBJECTIVE: To examine the relationships of body composition with basal serum estrone, estradiol, androstenedione, cortisol, growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels in 73 postmenopausal women. DESIGN: Cross-sectional study of hormone levels and body composition determined by dual-energy X-ray absorptiometry and anthropometry in women who were not taking oral hormone replacement therapy (HRT) and women taking HRT. Because high adiposity may modify hormone levels, subjects were grouped by fatness into obese (BMI >25 kg/m(2) and waist circumference >80 cm) and lean groups, as well as by HRT use. RESULTS: Total levels of estrone, estradiol, GH and cortisol were significantly higher and IGF-1 was lower in HRT users. In HRT users, estradiol levels were higher and GH levels were lower in obese than lean women. IGF-1 levels were lower in obese HRT users than lean nonusers. Total cortisol levels were significantly higher in lean HRT users than lean nonusers and obese users. GH and IGF-1 were significantly inversely correlated with trunk fat and percent body fat. Multiple regression revealed that only trunk fat was a significant (negative) determinant of GH and IGF-1 levels, whereas HRT use positively and negatively predicted GH and IGF-1, respectively. Percent body fat significantly predicted estradiol levels. Body composition did not differ by HRT use. CONCLUSIONS: Our results suggest that trunk fat attenuates the HRT-induced increase on GH levels. In addition, trunk fat is a significant determinant of low IGF-1 levels in postmenopausal women, and IGF-1 levels decline more with HRT use.