Pei-Yang Liu

Females have a greater incidence of stress fractures than males in both military and athletic populations: a systemic review.

OBJECTIVE The purpose of this study was to review incidence of stress fractures in military and athlete populations and identify factors explaining causes and differences in the incidence among genders. METHODS Searches were conducted using several major databases. The studies were included if they were original studies including both male and female subjects and their aim was to identify incidence rates and risk factors contributing to the development of stress fractures. Of several thousand studies, 11 focusing on military populations and 10 on athletes are discussed. RESULTS In both populations, females had higher incidence of stress fractures, with incidence of approximately 3% and approximately 9.2% for males and females, respectively, in military populations and approximately 6.5% and approximately 9.7%, respectively, in athletes. CONCLUSIONS Factors possibly explaining why females are more susceptible to stress fractures include bone anatomy, lower aerobic capacity, smaller muscle, and poor diet. However, both female recruits and athletes with normal weight and bone health are less likely to develop stress fractures, showing that gender is less important than the overall physical shape/condition.

The effects of a 6-month resistance training and dried plum consumption intervention on strength, body composition, blood markers of bone turnover, and inflammation in breast cancer survivors1

The purpose of this study was to examine the effects of resistance training (RT) and dried plum (DP) consumption on strength, body composition, blood markers of bone, and inflammation in breast cancer survivors (BCS). Twenty-three BCS (RT, n = 12; RT+DP, n = 11), aged 64 ± 7 years, were evaluated at baseline and after 6 months of intervention on the following: muscular strength (chest press and leg extension) via 1-repetition maximums (1RMs); body composition, specifically bone mineral density (BMD) by dual energy X-ray absorptiometry; biochemical markers of bone turnover (bone-specific alkaline phosphatase (BAP), tartrate resistant acid phosphatase (TRAP-5b)); and inflammation (C-reactive protein (CRP)). Target RT prescription was 2 days/week of 10 exercises, including 2 sets of 8-12 repetitions at ∼60%-80% of 1RM. RT+DP also consumed 90 g of DP daily. There were no baseline differences between groups or any group-by-time interactions for any of the variables. BCS increased upper (p < 0.05) (RT: 64 ± 14 to 80 ± 17 kg; RT+DP: 72 ± 23 to 91 ± 20 kg) and lower (p < 0.05) (RT: 69 ± 20 to 87 ± 28 kg; RT+DP: 78 ± 19 to 100 ± 21 kg) body strength. Body composition and BMD improvements were not observed. TRAP-5b decreased in the RT group (p < 0.05) (4.55 ± 1.57 to 4.04 ± 1.63 U/L) and the RT+DP group (p = 0.07) (5.10 ± 2.75 to 4.27 ± 2.03 U/L). Changes in BAP and CRP were not observed. RT was effective for improving biochemical markers of bone turnover and muscular strength in BCS. A longer and higher intensity intervention may be needed to reveal the true effects of RT and DP on body composition and biochemical markers of inflammation.

Effects of Resistance Training and Walking on Cardiovascular Disease Risk in African-American Women

PURPOSE The studys purpose was to evaluate the effects of walking (W) and walking plus resistance training (WRT) on cardiovascular disease risk factors in inactive middle-aged (49.0 ± 5.5 yr) African-American women (body mass index = 34.7 ± 6.4 kg·m(-2)). METHODS Body composition, blood pressure, HDL cholesterol, triglycerides, glycosylated hemoglobin (HbA1c), C-reactive protein, and fibrinogen were measured before and after a 12-wk exercise intervention. Subjects were randomly assigned to one of two training groups. The W group (n = 25) was instructed to increase daily pedometer-measured walking to ≥10,000 steps per day, whereas the WRT group (n = 19) was given the same walking prescription plus supervised resistance training 2 d·wk(-1). A two-way repeated-measures ANOVA with an intention-to-treat analysis was performed to examine changes between groups. Significance was accepted at P ≤ 0.05. RESULTS Both groups significantly (P < 0.001) increased walking (W = 5453 ± 2119 to 6845 ± 2279 steps per day, WRT = 4823 ± 1758 to 6859 ± 2012 steps per day). WRT significantly (P < 0.001) increased both upper (100 ± 15 to 113 ± 18 kg) and lower (102 ± 20 to 116 ± 25 kg) body strength compared with W. WRT significantly decreased waist circumference (94.8 ± 12.3 to 92.9 ± 12.0 cm, P = 0.021) and total fat mass (42.6 ± 11.1 to 41.8 ± 10.8 kg, P = 0.036) compared with W. WRT also significantly decreased pre- to postintervention body fat (45.8% ± 6.2% to 45.3% ± 6.2%, P = 0.018), HbA1c (5.9% ± 1.2% to 5.6% ± 1.0%, P = 0.028), and mean glucose calculated from HbA1c (122 ± 39 to 114 ± 32 mg·dL(-1), P = 0.028), whereas W showed no changes. Blood pressure, HDL cholesterol, triglycerides, and C-reactive protein were not affected by either intervention. CONCLUSIONS Although both interventions increased steps per day, WRT was more effective in improving several body composition measures and glucose control in 12 wk. WRT may be an important addition to a lifestyle intervention aiming to facilitate reductions in cardiovascular disease risk factors in overweight and obese African-American women.

Physical performance in relation to body composition and bone mineral density in healthy, overweight, and obese postmenopausal women.

Background and Purpose:Diminished physical performance can be detrimental among the older adults, causing falls and subsequent fractures, loss of independence, and increased morbidity and mortality rates. Therefore, it is important to maintain functional ability from the early onset of aging. The purpose of this study was to investigate the relationship between physical performance measures and body composition (bone, fat, and lean mass) in healthy, overweight and obese, early postmenopausal white women. Methods:A total of 97 participants aged 56.0 (4.4) years (mean (SD)) with body mass index of 31.0 (4.6) kg/m2 were included. Weight and height were recorded and 3 days of dietary records and physical activity were collected. Dual-energy x-ray absorptiometry measurements for body composition and bone mineral density were performed. Fasting blood samples were used for serum 25-hydroxy vitamin D (25OHD) analysis. Measures of physical performance included handgrip strength, 8-meter walking speed, one-leg-stance time, 8-foot Timed Get-Up-and-Go Test, and chair sit-to-stand test. Results:Results showed that higher lean mass was related to better physical performance on items assessing body strength, including handgrip (r ranged from 0.22 to 0.25, P < .05) while higher body fat was related to the poorer physical performance in each of the assessed measures. Bone mineral density of the forearm was positively related to the handgrip strength (r = 0.207, P < .05). In regression analyses (controlled for age, weight, height, serum 25OHD status, calcium intake, physical activity, and smoking), fat mass of the lower extremities was inversely related to walking speed, one-leg-stance time, and Get-Up-and-Go measures, all crucial for mobility (r2 = 0.13-0.23, P < .05). Conclusions:Overall, higher fat and lower lean mass was related to poorer physical performance, while forearm bone mineral density was related to the handgrip strength only. Further investigation may be beneficial for a better understanding of how body composition may prevent decline in physical performance among overweight/obese, mid-age, and older women.

Validation of body adiposity index as a measure of obesity in overweight and obese postmenopausal white women and its comparison with body mass index

ObjectiveThe purpose of this study was to evaluate whether the recently developed body adiposity index (BAI) in Mexican American and African American women could be validated in postmenopausal American white women and to determine if it is a better obesity classification measure than body mass index (BMI) is in the latter population. MethodsTotal body percentage adiposity (%adiposity) measured by dual-energy x-ray absorptiometry (DXA) was compared with total body %adiposity predicted by BAI in 187 overweight/obese postmenopausal white women (mean ± SD %adiposity, 45.9 ± 4.9% and 38.3 ± 6.2% for DXA and BAI, respectively). SPSS 19.0 and Medcalc 11.6.1.0 were used to conduct Pearson’s correlations (r), paired t test, receiver operating curve, and Lin’s concordance coefficient (&rgr;c) and to create Bland and Altman’s limit-of-agreement plot. ResultsPearson’s correlation analysis revealed a strong association between DXA %adiposity and BAI (r = 0.78, P < 0.001), DXA %adiposity and BMI (r = 0.75, P < 0.001), and BMI and BAI (r = 0.90, P < 0.001). Bias correction factor was 0.51 between DXA %adiposity and BAI. Paired t test showed a significant mean difference between measurements (P < 0.0001), and the plot showed that BAI underestimated DXA %adiposity by 7.56%. Concordance coefficient (&rgr;c = 0.39; 95% CI, 0.33-0.46) revealed a poor agreement strength. There was no difference between the area under the curve statistic for BAI and BMI. ConclusionBased on our results, BAI has limitations for use in a clinical setting in overweight/obese postmenopausal white women but may be practical for research applications and eventually developed into an easy method to estimate overweight/obesity in other settings.

Aerobic Exercise and Whole-Body Vibration in Offsetting Bone Loss in Older Adults

Osteoporosis and its associated fractures are common complications of aging and most strategies to prevent and/or treat bone loss focused on antiresorptive medications. However, aerobic exercise (AEX) and/or whole-body vibration (WBV) might have beneficial effect on bone mass and provide an alternative approach to increase or maintain bone mineral density (BMD) and reduce the risk of fractures. The purpose of this paper was to investigate the potential benefits of AEX and WBV on BMD in older population and discuss the possible mechanisms of action. Several online databases were utilized and based on the available literature the consensus is that both AEX and WBV may increase spine and femoral BMD in older adults. Therefore, AEX and WBV could serve as nonpharmacological and complementary approaches to increasing/maintaining BMD. However, it is uncertain if noted effects could be permanent and further studies are needed to investigate sustainability of either type of the exercise.

Evidence for the Association between Abdominal Fat and Cardiovascular Risk Factors in Overweight and Obese African American Women

Objective: To determine the association between total body fat and abdominal region fat derived from dual-energy x-ray absorptiometry (DXA) scans and cardiovascular disease (CVD) risk factors in middle- to older-aged African American (AA) women. We also compared tape-measured waist and hip circumference and their ratio (WHR) with DXA measurements in the context of CVD risk factor predictability. Methods: Participants included 59 overweight or obese African American women (age, 48.7 ± 5.6 years). Anthropometries, including waist and hip circumferences, were measured, and DXA scans were used to derive fat mass from the total body and abdominal region. Blood analyses included glucose, total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, total cholesterol/HDL and LDL/HDL ratios, C-reactive protein (CRP), and fibrinogen. Multiple linear regression models were used to investigate the association among DXA-derived fat mass measures, waist circumference, WHR, and cardiovascular risk factors. Results: Among DXA-derived fat mass measures, DXA-derived abdominal fat mass showed the best prediction for glucose and triglycerides, although waist circumference and DXA-derived abdominal fat mass had equivalent capacity for predicting the total cholesterol/HDL ratio. Furthermore, waist circumference showed the best prediction for LDL/HDL ratio and CRP. Conclusions: Both DXA-derived abdominal fat mass and waist circumference had comparable capacity for predicting blood lipid profiles and CRP. Therefore, if waist circumference is measured correctly, it could be used as the simplest means of predicting CVD risk factors in overweight/obese AA women when DXA is not available.

Vitamin D Status and Framingham Risk Score in Overweight Postmenopausal Women

BACKGROUND Epidemiologic studies have suggested associations between vitamin D status and coronary heart disease (CHD) risk. The purpose of this work was to determine if vitamin D status was predictive of CHD risk assessed by Framingham risk score (FRS) in overweight, Caucasian, postmenopausal women, using the baseline data collected in a clinical trial. METHODS The study comprised 178 women aged 42-67 years (mean±standard deviation [SD] 55.7±4.3). Fasting serum was used to analyze blood lipids and vitamin D. The status of the latter was determined based on serum 25-hydroxyvitamin D [25(OH)D], with inadequacy defined as serum 25(OH)D <75 nmol/L (or <50.0 nmol/L, per new Institute of Medicine recommendations). Usual dietary intake and activity were assessed using 3-day food and 2-day activity records, respectively. Education, medical history, blood pressure, and anthropometric measures were obtained as well. Season was determined based on date of blood draw. RESULTS Mean serum 25(OH)D concentration was 65.3±27.5 nmol/L (range 7.0-147.6 nmol/L); 66% (n=118) and 32% (n=57) of subjects were vitamin D insufficient [25(OH)D <75 nmol/L or <50 nmol/L, respectively] of which 14% (n=25) were vitamin D deficient [25(OH)D <37.5 nmol/L]. Body mass index (BMI) was a significant negative and dietary vitamin D positive predictor of 25(OH)D. In hierarchical regression, FRS was predicted by education level only. No association was observed between 25(OH)D and FRS (p=0.981). CONCLUSIONS Serum 25(OH)D concentrations were inversely associated with BMI, but no relationship with FRS was found. Given the physiologic importance of vitamin D, further investigations aimed at determining the effects of obesity and heart disease on vitamin D requirements are warranted.

The Effects of Resistance Training on Physical Function and Quality of Life in Breast Cancer Survivors

Breast cancer survivors (BCS) exhibit decreased physical function and quality of life (QOL) following cancer treatments. Resistance training (RT) may elicit positive changes in physical and mental well-being. This study assessed 27 BCS, pre-and post-intervention (six months) on the following variables: muscular strength (via one repetition maximum (1RM) of chest press and leg extension), physical function (via the Continuous Scale-Physical Functional Performance test) and QOL (via the Short Form-36 survey). RT consisted of two days/week of ten exercises including two sets of 8–12 repetitions at 52%–69% of their 1RM. A repeated measures analysis of variance revealed BCS significantly (p < 0.05) increased upper (71 ± 22 to 89 ± 22 kg) and lower body (74 ± 18 to 93 ± 24 kg) strength, total physical function (65.5 ± 12.1 to 73.6 ± 12.2 units) and the subcomponents of physical function: upper body strength (63.5 ± 16.3 to 71.2 ± 16.8 units), lower body strength (58.5 ± 14.9 to 68.6 ± 16.3 units), balance and coordination (66.5 ± 12.2 to 74.6 ± 11.6 units), and endurance (67.2 ± 12.0 to 75.0 ± 11.6 units). No changes were observed over time for subjective measures of physical function and QOL. Results showed RT could be an effective means to improve objective physical function in BCS. Further research is needed to clarify the effects of RT on subjective physical function and QOL.