Comparison of EMG activity of medial and lateral hamstrings during isometric contractions at various cuff weight loads.

Since both the medial head (MH) and lateral head (LH) of the hamstring muscles contribute to knee flexion, this study investigated whether the relative electrical activity of these heads remained constant with respect to each other or changed during isometric contractions at five different resistance levels. The relative electrical activity of these two heads was determined by comparing their integrated EMG (iEMG). Forty-two volunteers with no history of right lower extremity injury or disease, between the ages of 18 and 35, were studied. Following motor point location, surface electrodes were placed over the MH and LH. Subjects, positioned prone, flexed the knee to 45 degrees using a sawhorse as a tactile cue to help maintain this position. Three recordings, 8 s in length, were taken at each subject's maximum isometric contraction and then using cuff weights of 1, 3, 5, and 7% of their body weight. The average of the three recordings was used in the analysis. During maximum isometric contraction (at 45 degrees of knee flexion), the LH contributes a significantly greater percent of the total iEMG (63.4%) than the MH (P < 0.0001). Furthermore, within the four submaximal levels tested, the LH's contribution was significantly greater than the MH (P < 0.01). During submaximal isometric contractions, the LH percent contribution to total iEMG was less than its contribution during maximal isometric contraction, all P values < 0.005. As a result, during these same submaximal isometric contractions, the MH contribution to total iEMG was greater than its contribution during maximal isometric contraction, all P values < 0.005).

School-based identification of asthma in a low-income population.

The increase in the prevalence, morbidity, and mortality of asthma among children over the last decade has been well documented, especially among low-income minority children. Hypotheses for the increases in morbidity and mortality include limited access to primary care services and the failure to recognize the presence and severity of asthma. The University of Miami Pediatric Mobile Clinic (Mobile Clinic) Asthma Intervention Program is designed to identify underserved asthmatic children at school and offer them culturally sensitive care. Nine elementary schools with low income, predominantly Hispanic and African-American populations regularly served by the Mobile Clinic, were chosen for study participation. All 5,800 students who were enrolled in kindergarten through third grade were given letters at the time of registration by their homeroom teachers about the asthma program. Caretakers who returned the questionnaire and reported that the student had asthma symptoms were invited to have the student undergo a medical evaluation in the Mobile Clinic. Over a 2-year period, caretakers of 423 students (7.3% of all students) expressed an interest in further evaluating their child's respiratory health. Of these, we enrolled and evaluated 154 in the Mobile Clinic's Asthma Intervention Program. The Mobile Clinic physicians identified 145 of the enrollees as having asthma. These results indicate that in elementary schools serving predominantly low-income minority populations, a large fraction of the asthmatic population (estimated prevalence, 6-10%) can be identified by a school-based letter. Further, in a subset of asthmatic students (children of interested caretakers), there is good agreement between caretaker responses and physician diagnosis of asthma. Since school attendance is mandatory, school-based methods may be an effective method for identifying low-income children with asthma.

Racial differences in visceral adipose tissue but not anthropometric markers of health-related variables.

This study sought to determine whether visceral adipose tissue (VAT) and/or its anthropometric surrogates could significantly predict health-related variables (HRV) in overweight Caucasian (CC) (n = 36) and African-American (AA) (n = 30) women. With the use of magnetic resonance imaging, findings showed significantly higher volume and area of VAT (P < 0.0001 for both) as well as higher triacylglycerol (P = 0.009) in CC compared with AA women. Furthermore, VAT volume, race, and VAT volume x race interaction could significantly predict triacylglycerol (P = 0.0094), high-density lipoprotein cholesterol (P = 0.0057), insulin (P = 0.0002), and insulin resistance (P < 0. 0001). Additionally, the VAT volume x race interaction for insulin (P = 0.040) and insulin resistance (P = 0.003) was significant. In a separate analysis, waist circumference and race predicted the identical variables. Our results support the use of volume or area of VAT in predicting HRV in CC women; however, its use in AA women appears limited. In contrast, waist circumference can provide a suitable VAT alternative for both CC and AA women; however, VAT clearly represents the more powerful predictor.

Effect of a combined walking and conversation intervention on functional mobility of nursing home residents with Alzheimer disease.

Assisted walking and walking combined with conversation were compared to a conversation-only intervention in nursing home residents with Alzheimer disease. Sixty-five subjects randomly assigned to treatment group were tested at baseline and end of treatment. Subjects' mean Mini-Mental State Examination score was 10.83; mean age was 87. Treatment was given for 30 minutes three times a week for 16 weeks. Subjects in the assisted walking group declined 20.9% in functional mobility; the conversation group declined 18.8%. The combined walking and conversation treatment group declined only 2.5%. These differences in outcome were significant and appear to have been affected by differences in treatment fidelity. Subjects in the conversation treatment group completed 90% of intended treatment compared with 75% in the combined group and only 57% in the assisted walking group. Failure to treat was due to subject refusal and physical illness. The conversation component of the combined walking and conversation treatment intervention appears to have improved compliance with the intervention, thereby improving treatment outcome. Results indicate that assisted walking with conversation can contribute to maintenance of functional mobility in institutionalized populations with Alzheimer disease. Staff assigned to this task should be prepared to use effective communication strategies to gain acceptance of the intervention.

Risk for metabolic control problems in minority youth with diabetes.

OBJECTIVE: We examined and quantified the degree of risk for poor glycemic control and hospitalizations for diabetic ketoacidosis (DKA) among black, Hispanic, and white children and adolescents with diabetes. RESEARCH DESIGN AND METHODS: We examined ethnic differences in metabolic control among 68 black, 145 Hispanic, and 44 white children and adolescents with type 1 diabetes (mean age 12.9 [range 1-21] years), who were primarily of low socioeconomic status. Clinical and demographic data were obtained by medical chart review. Glycohemoglobins were standardized and compared across ethnic groups. Odds ratios among the ethnic groups for poor glycemic control and hospitalizations for DKA were also calculated. RESULTS: The ethnic groups were not different with respect to age, BMI, insulin dose, or hospitalizations for DKA, but black children were older at the time of diagnosis than Hispanics (P < 0.05) and were less likely to have private health insurance than white and Hispanic children (P < 0.001). Black youths had higher glycohemoglobin levels than white and Hispanic youths (P < 0.001 after controlling for age at diagnosis). Black youths were also at greatest risk for poor glycemic control (OR = 3.9, relative to whites; OR = 2.5, relative to Hispanics). CONCLUSIONS: These results underscore and quantify the increased risk for glycemic control problems of lower-income, black children with diabetes. In the absence of effective intervention, these youths are likely to be overrepresented in the health care system as a result of increased health complications related to diabetes.

Clinical predictability of the waist-to-hip ratio in assessment of cardiovascular disease risk factors in overweight, premenopausal women.

The waist-to-hip ratio (WHR) is one of the most commonly used anthropometric measures to indicate a central obesity pattern and an increased risk of cardiovascular disease in normal-weight women. Although the American Heart Association has reported that a WHR >0.80 be used to indicate increased risk of cardiovascular disease in women, the present study assessed the WHR above which is seen elevations in cardiovascular disease risk factors in a sample of overweight women. Using data from 240 women aged 27.5-47.5 y enrolled in a university weight-loss program, we determined WHR quartiles: <0.80, 0.80 to <0.84, 0.84 to <0.90, and > or =0.90. Subjects were placed into high-risk categories for cardiovascular disease on the basis of age- and population-defined norms. Women had an increased likelihood of elevated VLDL cholesterol, triacylglycerol, diastolic blood pressure, and composite risk (ie, having > or =4 cardiovascular disease risk factors) and an increased risk of having low concentrations of HDL at a WHR > or =0.90. All aforementioned variables had a significant odds ratio at a WHR > or =20.90 after adjustment for smoking, whereas elevated VLDL, triacylglycerol, and diastolic blood pressure were observed at this WHR after adjustment for a body mass index (in kg/m2) < or > or =35. Only 2 variables, VLDL and triacylglycerol, had a significant odds ratio at a WHR <0.90 before and after adjustment for BMI and smoking. These data suggest an upward shift in the critical threshold for WHR to > or =0.90, at which point there was an elevation in cardiovascular disease risk factors in already overweight women. This trend persisted regardless of whether the women smoked or whether their body mass index was < or > or =35.

The relationship between fat distribution and coronary risk factors in sedentary postmenopausal women on and off hormone replacement therapy.

The purpose of this study was to examine the relationship between fat distribution and coronary risk factors (CRF) in sedentary overweight postmenopausal women both on and off hormone replacement therapy (HRT). Medical records and information were abstracted from nonsmoking women entering a weight loss program. A total of 33 women on HRT (mean age=50.12+/-5.2) and 51 nonusers (mean age=52.52+/-7.8) fulfilled subject eligibility requirements and were included in the data analysis. Results showed a significantly lower waist-to-hip ratio (WHR) (p=0.009) and waist (p=0.010) and greater levels of high-density lipoprotein cholesterol (HDL-C) (p=0.035) in HRT users than in nonusers. After converting correlations to standard Z-scores and performing z-tests, the correlation between total cholesterol (T-Chol) and WHR was significantly greater in nonusers than in HRT users (p=0.038). A multiple regression analysis showed differences between groups in the ability of age and anthropometric variables to predict CRF. Although T-Chol could be predicted in nonusers (r2=0.24; p=0.011), very low-density lipoprotein cholesterol (VLDL-C) and systolic blood pressure (SBP) could be significantly predicted in HRT users only (r2=0.28, p=0.055 and r2=0.40, p=0.005 for VLDL-C and SBP, respectively). These data suggest that there are differences between HRT users and nonusers in predictors of CRF, central adiposity, HDL-C, and the relationship between WHR and T-Chol. It is concluded that the significantly lower levels of central adiposity observed in HRT users may have clinical benefits with regard to CRF.

Integrated EMG study of the medial and lateral heads of the gastrocnemius during isometric plantar flexion with varying cuff weight loads.

Both heads of the gastrocnemius muscle contribute to ankle plantar flexion. This study utilized integrated electromyography to investigate whether the percent electrical activity contributed by each head remained constant or changed during isometric contractions at five different resistance levels. Fifty healthy volunteers ranging in age from 19 to 34 years, with no history of musculoskeletal or neuromuscular disorders involving the right lower extremity, were studied. All tasks were performed in the prone position, knee in extension, with the leg and foot in neutral with respect to rotation. Motor points of the medial head and lateral head were identified and surface electrodes were placed just distal to them. The subjects maintained 20° of plantar flexion under five conditions: a maximal isometric plantar flexion contraction (one trial only), and with a 5-, 10-, 15- and 20-lb cuff weight attached to the right foot (three trials each). EMG recordings, 8 s in length, were taken during the isometric contractions. Integrated EMGs were averaged for each cuff weight and the resulting values used in the analysis. A repeated measures ANOVA was performed and a significance level of p≤0.05 was used to determine statistical significance. As weight increased, the absolute value of the integrated EMG recorded over both muscles increased, but the percent contributed by each head remained essentially equal (50%) within the four submaximal loads tested. However, for the maximal isometric contraction, the medial head contributed a significantly higher percentage of the total integrated EMG (58%). Therefore, in the open-chain activity described, the two heads of the gastrocnemius demonstrate similar neural drive at submaximal levels of contraction, but this changes as maximum isometric levels are reached.

Relation between anthropometric measures of fat distribution and cardiovascular risk factors in overweight pre- and postmenopausal women.

This study compared three different measures of central adiposity: waist-to-hip ratio (WHR), waist-to-height ratio (WSHT), and waist circumference with cardiovascular risk factors, including serum lipoproteins and blood pressure in overweight pre- (n = 115) and postmenopausal (n = 46) women. Premenopausal women had a mean age of 35.6 +/- 6.79 y and a mean body mass index (BMI; in kg/m2) of 37.08 +/- 6.01. Postmenopausal women had a mean age of 52.5 +/- 8.19 y and a mean BMI of 38.75 +/- 6.9. Although several correlations between central adiposity and serum lipoproteins and blood pressure were significant, they were unaffected by menopausal status. There were also no significant differences among the three measures of central adiposity in relation to cardiovascular risk factors within premenopausal and postmenopausal groups. An analysis of covariance controlling for BMI showed that after stratifying WSHT into tertiles, a significant interaction of WSHT group by menopausal status was found for systolic blood pressure (SBP) (P = 0.019). Postmenopausal women had a significantly greater SBP than premenopausal women in the lowest and highest tertiles (P = 0.001); however, this pattern was not shown in the middle WSHT tertile. The relation between central adiposity and cardiovascular risk factors appears to be unchanged after menopause, except when WSHT is used to indicate SBP. Because increased central adiposity may also indicate an increase in cardiovascular risk factors, measurements of central adiposity can be used to supplement the routine clinical evaluation of cardiovascular risk factors in both pre- and postmenopausal overweight women.

Reliability and validity of the Wheelchair User's Shoulder Pain Index (WUSPI).

Many long term wheelchair users develop shoulder pain. The purpose of this study was to examine the reliability and validity of the Wheelchair User's Shoulder Pain Index (WUSPI), an instrument which measures shoulder pain associated with the functional activities of wheelchair users. This 15-item functional index was developed to access shoulder pain during transfers, self care, wheelchair mobility and general activities. To establish test-retest reliability, the index was administered twice in the same day to 16 long term wheelchair users and their scores for the two administrations were compared by intraclass correlation. To establish concurrent validity, the index was administered to 64 long term wheelchair users and index scores were compared to shoulder range of motion measurements. Results showed that intraclass correlation for test-retest reliability of the total index score was 0.99. There were statistically significant negative correlations of total index scores to range of motion measurements of shoulder abduction (r = -0.485), flexion (r = -0.479) and shoulder extension (r = -0.304), indicating that there is a significant relationship of total index score to loss of shoulder range of motion in this sample. The Wheelchair User's Shoulder Pain Index shows high levels of reliability and internal consistency, as well as concurrent validity with loss of shoulder range of motion. As a valid and reliable instrument, this tool may be useful to both clinicians and researchers in documenting baseline shoulder dysfunction and for periodic measurement in longitudinal studies of musculoskeletal complications in wheelchair users.

Development of the Wheelchair User's Shoulder Pain Index (WUSPI).

Chronic shoulder pain is a frequently reported phenomenon in individuals who use wheelchairs as their primary means of mobility. No indices are currently available which detect difficulties in performing daily activities due to shoulder discomfort in a largely independent population of wheelchair users. The Wheelchair User's Shoulder Pain Index (WUSPI) was designed to measure shoulder pain in individuals who use wheelchairs. A pilot index was created to measure shoulder pain and related difficulty during basic and instrumental activities of daily living. The instrument was administered to 64 wheelchair users at an athletic event. Analyses of internal consistency and interitem correlations were used to revise and refine the original instrument. Individual item analysis revealed that the subjects in this study experienced the most shoulder pain when wheeling up an incline or on outdoor surfaces, when lifting an object from an overhead shelf, when trying to sleep, when transferring from tub to wheelchair and when washing their backs. The final 15-item index shows high internal consistency. This instrument is useful for both clinical and research purposes to detect and monitor shoulder pain and accompanying loss of function by wheelchair users.