Effect of Intrapleural Fibrinolytic Therapy vs Surgery for Complicated Pleural Infections: A Randomized Clinical Trial

Importance

There is a paucity of high-quality prospective randomized clinical trials comparing intrapleural fibrinolytic therapy (IPFT) with surgical decortication in patients with complicated pleural infections.

Objective

To assess the feasibility, safety, and efficacy of an algorithm comparing tissue plasminogen activator plus deoxyribonuclease therapy with surgical decortication in patients with complicated pleural infections.

Design, Setting, and Participants

This parallel pilot randomized clinical trial was performed at a single urban community-based center from March 1, 2019, to December 31, 2021, with follow-up for 90 days. Seventy-four individuals were screened and 48 were excluded. Twenty-six patients 18 years or older with clinical pleural infection and positive findings of pleural fluid analysis were included. Of these, 20 patients underwent randomized selection (10 in each group), and 6 were observed.

Interventions

Intrapleural tissue plasminogen activator plus deoxyribonuclease therapy vs surgical decortication.

Main Outcomes and Measures

Primary outcomes were the percentage of patients enrolled to study completion and multidisciplinary adherence. Secondary outcomes included the number of patients with and the reason for inadequate screening, screening to enrollment failures, time to accrual of 20 patients or the number accrued at 1 year, and clinical data.

Results

Twenty-six patients were enrolled, 10 were randomized to each group, and 6 were observed. There was 100% enrollment to study completion in each treatment group, no protocol deviations, 2 minor protocol amendments, and no screening to enrollment failures. It took 32 months to enroll 26 patients. The 20 randomized patients had a median age of 57 (IQR, 46-65) years, were predominantly men (15 [75%]), and had a median RAPID (Renal, Age, Purulence, Infection Source, and Dietary Factors) score of 2 (IQR, 1-3). Treatment failure occurred in 1 patient and 2 crossover treatments occurred, all of which were in the IPFT group. Intraprocedure and postprocedure complications were similar between the groups. There were no reoperations or in-hospital deaths. Median duration of chest tube use was comparable in the IPFT (5 [IQR, 4-8] days) and surgery (4 [IQR, 3-5] days) groups (P = .21). Median hospital stay tended to be longer in the IPFT (11 [IQR, 4-18] days) vs surgery (5 [IQR, 4-6] days) groups, although the difference as not significantly different (P = .08). There were no 30-day readmissions or 30- or 90-day deaths.

Conclusions and Relevance

In this pilot randomized clinical trial, the study algorithm was feasible, safe, and efficacious. This provides evidence to move forward with a multicenter randomized clinical trial.

Trial Registration

ClinicalTrials.gov Identifier: NCT03873766.

The Impact of Ineffective Esophageal Motility on Patients Undergoing Magnetic Sphincter Augmentation

OBJECTIVE

To evaluate and characterize outcomes of MSA in patients with IEM.

SUMMARY BACKGROUND DATA

MSA improves patients with gastroesophageal reflux and normal motility. However, many patients have IEM, which could impact the outcomes of MSA and discourage use.

METHODS

An international, multi-institutional case control study of IEM patients undergoing MSA matched to normal patients was performed. Primary outcomes were new onset dysphagia and need for postoperative interventions.

RESULTS

A total of 105 IEM patients underwent MSA with matching controls. At 1 year after MSA: GERD-Health Related Quality of Life was similar; DeMeester scores in IEM patients improved to 15.7 and 8.5 in controls ( P = 0.021); and normalization of the DeMeester score for IEM = 61.7% and controls = 73.1% ( P = 0.079).In IEM patients, 10/12 (83%) with preop dysphagia had resolution; 11/66 (17%) had new onset dysphagia and 55/66 (83%) never had dysphagia. Comparatively, in non-IEM patients, 22/24 (92%) had dysphagia resolve; 2/24 (8%) had persistent dysphagia; 7/69 (10%) had new onset dysphagia, and 62/69 (90%) never had dysphagia.Overall, 19 (18%) IEM patients were dilated after MSA, whereas 12 (11%) non-IEM patients underwent dilation ( P = 0.151). Nine (9%) patients in both groups had their device explanted.

CONCLUSIONS

Patients with IEM undergoing MSA demonstrate improved quality of life and reduction in acid exposure. Key differences in IEM patients include lower rates of objective GERD resolution, lower resolution of existing dysphagia, higher rates of new onset dysphagia and need for dilation. GERD patients with IEM should be counselled about these possibilities.

Cumulative radiation dose incurred during the management of complex pleural space infection

BACKGROUND

Complex pleural space infections are commonly managed with antibiotics, pleural drainage, intrapleural fibrinolytic therapy, and surgery. These strategies often utilize radiographic imaging during management, however little data is available on cumulative radiation exposure received during inpatient management. We aimed to identify the type and quantity of radiographic studies along with the resultant radiation exposure during the management of complex pleural space infections.

METHODS

Retrospective review of community network healthcare system from January 2015 to July 2018. Patients were identified through billing databases as receiving intrapleural fibrinolytic therapy and/or surgical intervention. Patient demographics, clinical outcomes, and inpatient radiographic imaging was collected to calculate cumulative effective dose.

RESULTS

A total of 566 patients were identified with 7275 total radiographic studies performed and a median cumulative effective dose of 16.9 (IQR 9.9-26.3) mSv. Multivariable linear regression analysis revealed computed tomography use was associated with increased cumulative dose, whereas increased age was associated with lower cumulative dose. Over 74% of patients received more than 10 mSv, with 7.4% receiving more than 40 mSv.

CONCLUSIONS

The number of radiographic studies and overall cumulative effective dose in patients hospitalized for complex pleural space infection was high with the median cumulative effective dose > 5 times normal yearly exposure. Ionizing radiation and modern radiology techniques have revolutionized medical care, but are likely not without risk. Additional study is warranted to identify the frequency and imaging type needed during complex pleural space infection management, attempting to keep ionizing radiation exposure as low as reasonably possible.

Is mechanical embolectomy performed in nonanesthetized patients effective?

BACKGROUND AND PURPOSE

In centers performing endovascular treatment for patients with AIS, there is variability in placing patients under general anesthesia. Nonanesthetized patients might move during the procedure leading to complications and prolonging the time to revascularization due to lack of cooperation. However, general anesthesia can lead to a delay of the procedure, an inability to assess the patient during the procedure, and fluctuations of blood pressure. Our center does not routinely either use general anesthesia or sedate patients. We report our experience with nonanesthetized patients undergoing emergent mechanical embolectomy.

MATERIALS AND METHODS

We performed a retrospective analysis of 66 consecutive patients enrolled in the MERCI Registry at our center from June 2007 to June 2009. A univariate statistical analysis was performed by using the Fisher exact test for categoric variables and the Student t test for continuous variables in comparing use of general anesthesia with nonanesthetized patient demographics, procedural times, procedural complications, good outcome, and mortality.

RESULTS

Nine patients (13.6%) were placed under general anesthesia, and 57 (86.4%) were awake. Higher baseline NIHSS scores and older age were statistically associated with general anesthesia. No significant difference occurred between groups in the time to groin puncture or procedural times. Revascularization rates were 77% for general anesthesia patients and 70% for nonanesthetized patients (P = .331). The nonanesthetized group had better outcomes, but we did not control these outcomes for other factors. Complications were much more frequent in the general anesthesia patients (22%) than in the nonanesthetized patients (3.5%) (P = .0288).

CONCLUSIONS

Performing mechanical embolectomy in nonanesthetized patients at our institution does not prolong procedure time, decrease revascularization rates, increase complication rates, or decrease good outcome. Mechanical embolectomy in nonanesthetized patients is effective and should be considered an option in the treatment of the patient with AIS.

Can we use the Jackson and Pollock equations to predict body density/fat of obese individuals in the 21st century?

OBJECTIVE: Jackson and Pollock's (JP) ground-breaking research reporting generalized body density equations to estimate body fat was carried out in the late 1970s. Since then we have experienced an 'obesity epidemic'. Our aim was to examine whether the original quadratic equations established by Jackson and co-workers are valid in the 21st century. METHODS: Reanalyzing the original JP data, an alternative, more biologically sound exponential power-function model for body density is proposed that declines monotonically, and hence predicts body fat to rise monotonically, with increasing skin-fold thicknesses. The model also remains positive irrespective of the subjects' sum-of-skinfold thicknesses or age. RESULTS: Compared to the original quadratic model proposed by JP, our alternative exponential power-function model is theoretically and empirically more accurate when predicting body fat of obese subjects (sums of skinfolds >120mm). A cross-validation study on 14 obese subjects confirmed these observations, when the JP quadratic equations under estimated body fat predicted using dual energy x-ray absorptiometry (DXA) by 2.1% whereas our exponential power-function model was found to underestimate body fat by less than 1.0%. Otherwise, the agreement between the DXA fat (%) and the two models were found to be almost identical, with both coefficients of variation being 10.2%. CONCLUSIONS: Caution should be exercised when predicting body fat using the JP quadratic equations for subjects with sums of skinfolds>120 mm. For these subjects, we recommend estimating body fat using the tables reported in the present manuscript, based on the more biologically sound and empirically valid exponential power-function model.

Genetic variation and decreased risk for obesity in the Atherosclerosis Risk in Communities Study

AIM

To investigate the effects of variation in the leptin [LEP (19A>G)] and melanocortin-4 receptor [MC4R (V103I)] genes on obesity-related traits in 13 405 African-American (AA) and white participants from the Atherosclerosis Risk in Communities (ARIC) Study.

METHODS

We tested the association between the single-locus and multilocus genotypes and obesity-related measures [body mass index (BMI), body weight (BW), waist-hip ratio, waist circumference and leptin levels], adjusted for age, physical activity level, smoking status, diabetic status, prevalence of coronary heart disease, hypertension, stroke or transient ischaemic attack.

RESULTS

AA and white female carriers of the MC4R I103 allele exhibited significantly lower BW than non-carriers of this allele (p < 0.05 and p < 0.01 respectively). AA female carriers of both the LEP A19 allele and the MC4R I103 allele were 63% [odds ratio (OR) = 0.37, 95% confidence interval (CI) (0.18-0.78)] less likely to be obese, and white female carriers of the same two alleles were 46% [OR = 0.54, 95% CI (0.32-0.91)] less likely to be obese, than non-carriers of the variant alleles. Female carriers of both the LEP A19 and MC4R I103 alleles had significantly lower BW (p < 0.05), BMI (p < 0.05) and plasma leptin (p < 0.01) than the non-carriers of both the alleles. Carriers of the two variant alleles had lower BMI over the 9-year course of the ARIC study and significantly lower weight gain from age 25 years. No significant joint effect of these two variants was observed in males.

CONCLUSION

These results suggest that variation within the LEP and MC4R genes is associated with reduced risk for obesity in females.

Generalized abdominal visceral fat prediction models for black and white adults aged 17–65 y: the HERITAGE Family Study

OBJECTIVE

To determine if the relationship between abdominal visceral fat (AVF) and measures of adiposity are different between Black and White subjects and to develop valid field prediction models that accurately identify those individuals with AVF levels associated with high risk for chronic disease.

DESIGN

Cross-sectional measurements obtained from 91 Black men, 137 Black women, 227 White men, and 237 White women subjects, ages 17-65 y, who were participants in the HERITAGE Family Study, both at baseline and following 20 weeks of endurance training.

MEASUREMENTS

AVF, abdominal subcutaneous fat (ASF), abdominal total fat (ATF), and sagittal diameter (SagD) were measured by computed tomography (CT). Body density was determined by hydrostatic weighing and was used to estimate relative body fat. Arm, waist (WC), and hip circumferences and skinfold thickness measures were taken, and BMI was calculated from weight (kg) and height (m(2)). Since CT abdominal fat variables were skewed, a natural log transformation (Ln) was used to produce a normal distribution. The General Linear Model (GLM) procedure was used to test the relationship between AVF and two different groups of variables-CT and anthropometric.

RESULTS

The AVF of White men and women was significantly higher than that of Black men and women, independent of BMI, WHR, WC, and age, and was greater for men than for women. The CT model showed that the combination of SagD, Ln (ASF), age, and race accounted for 84 and 75% of the variance in AVF in men and women, respectively. The anthropometric model provided two valid generalized field AVF prediction equations. The Field-I equation, which included BMI, WHR, age and race, had an r(2) of 0.78 and 0.73 for men and women, respectively. The Field-II equation, which included BMI (women only), WC, age, and race, had an r(2) of 0.78 and 0.72 for men and women, respectively. The field model equations became less accurate as the estimated AVF increased.

CONCLUSIONS

(1) At the same age and level of adiposity, Black men and women have less AVF than White men and women. These differences are greater in men than in women. (2) The field regression equations can be generalized to the diverse group of adults studied, both in an untrained and trained state. However, their accuracy decreases with increasing levels of AVF.

Measuring Aerobic Fitness of Hispanic Youth 10 to 12 years of Age

Obesity is a major health problem in the U.S., especially for Hispanic youth. Because maximal/peak oxygen consumption (V.O (2)peak) is one predictor of future weight gain in children, valid field-based methods for determining V.O (2)peak in Hispanic children are needed. The purpose of this study was to validate a field-based aerobic fitness test, the 20-m shuttle test (20-MST), in Hispanic boys (n = 58) and girls (n = 67), 10 - 12 years old (mean age +/- SD, 10.7 +/- 0.6 y). Measured V.O (2)peak was determined during a maximal, graded treadmill test using the Bruce protocol. The 20-MST was administered per a standard protocol. Maximal speed attained on the 20-MST and age were used to estimate V.O (2)peak. An intraclass coefficient of 0.82 was obtained on 35 students (16 boys; r = 0.85 and 19 girls; r = 0.79) who completed the 20-MST twice, 1-wk apart. Estimated (44.3 ml x kg (-1) x min (-1) ) and measured (45.1 ml x kg (-1) x min (-1)) V.O (2)peak were not significantly different (p = 0.33). The correlation between the two V.O (2)peak parameters was r = 0.62; p < 0.001, the standard error of the estimate (SEE) was 3.91 ml x kg (-1) x min (-1), and 85.5 % of the measured V.O (2)peak values fell within 5.9 ml x kg (-1) x min (-1) of estimated V.O (2)peak. The weight status of the child did not significantly change these results. The 20-MST combined with the Leger et al. equation is a valid method for predicting V.O (2)peak in Hispanic youth. The test can be used to provide valuable information for intervention design and disease prevention.

Generalized equations for predicting body density of men. 1978

1. Skinfold thickness, body circumferences and body density were measured in samples of 308 and ninety-five adult men ranging in age from 18 to 61 years. 2. Using the sample of 308 men, multiple regression equations were calculated to estimate body density using either the quadratic or log form of the sum of skinfolds, in combination with age, waist and forearm circumference. 3. The multiple correlations for the equations exceeded 0.90 with standard errors of approximately +/-0.0073 g/ml. 4. The regression equations were cross validated on the second sample of ninety-five men. The correlations between predicted and laboratory-determined body density exceeded 0.90 with standard errors of approximately 0.0077 g/ml. 5. The regression equations were shown to be valid for adult men varying in age and fatness.

The effect of sex, age and race on estimating percentage body fat from body mass index: The Heritage Family Study

OBJECTIVE

To study the effects of sex, age and race on the relation between body mass index (BMI) and measured percent body fat (%fat).

DESIGN

Cross-sectional validation study of sedentary individuals.

SUBJECTS

The Heritage Family Study cohort of 665 black and white men and women who ranged in age from 17 to 65 y.

MEASUREMENTS

Body density determined from hydrostatic weighing. Percentage body fat determined with gender and race-specific, two-compartment models. BMI determined from height and weight, and sex and race in dummy coded form.

RESULTS

Polynomial regression showed that the relationship between %fat and BMI was quadratic for both men and women. A natural log transformation of BMI adjusted for the non-linearity. Test for homogeneity of log transformed BMI and gender showed that the male-female slopes were within random variance, but the intercepts differed. For the same BMI, the %fat of females was 10.4% higher than that of males. General linear models analysis of the women's data showed that age, race and race-by-BMI interaction were independently related to %fat. The same analysis applied to the men's data showed that %fat was not just a function of BMI, but also age and age-by-BMI interaction. Multiple regression analyses provided models that defined the bias.

CONCLUSIONS

These data and results published in the literature show that BMI and %fat relationship are not independent of age and gender. These data showed a race effect for women, but not men. The failure to adjust for these sources of bias resulted in substantial differences in the proportion of subjects defined as obese by measured %fat.

Predicting physical therapy visits needed to achieve minimal functional goals after arthroscopic knee surgery

STUDY DESIGN

Retrospective, cross-sectional regression modeling.

OBJECTIVE

To predict physical therapy visits following arthroscopic knee surgery.

BACKGROUND

The number of physical therapy visits required to achieve a set of specific minimal-level goals (full knee extension, straight leg raise, normalized gait pattern, bicycle pedaling, and independent home exercises) that are related to decreased complication rates has not previously been modeled.

METHODS AND MEASURES

A multiple regression model to predict postoperative physical therapy visits was developed using subject demographics and 2 simple clinical measures, degree of straight leg raise lag and total range of motion. All data were collected from 148 patient charts. Model validity was examined by the predicted residual sum of squares technique and a second independent sample of 157 charts.

RESULTS

Diagnosis group, surgery group, and range of motion were the significant variables predicting visits in the final model (R2 = 0.384). Results of model validation analyses using predicted residual sum of squares technique (R2 = 0.346) and the second set of data (R2 = 0.282) were satisfactory. Analysis of residuals (difference of observed and predicted visits) showed prediction of the number of physical therapy visits within 3 visits for approximately 75% of the cases in both sets of data.

CONCLUSIONS

Using the model to predict physical therapy visits following arthroscopic knee surgery was more accurate than using diagnosis alone, except for lateral retinacular release. This study demonstrates how regression models could be used to explain variance in physical therapy visits for a given set of minimal functional goals.

Determining the amount of physical activity needed for long-term weight control

OBJECTIVE

To evaluate prospectively the influence of habitual physical activity on body weight of men and women and to develop a model that defines the role of physical activity on longitudinal weight change.

DESIGN AND SETTING

Occupational cohort study conducted for a mean of 5.5 y.

SUBJECTS

A total of 496 (341 male and 155 female) NASA/Johnson Space Center employees who completed the 3 month education component of the employee health-related fitness program and remained involved for a minimum of 2 y.

MEASUREMENTS

Body weights were measured at baseline (T1) and follow-up (T2), and habitual physical activity was obtained from the mean of multiple ratings of the 11-point (0-10) NASA Activity Scale (NAS) recorded quarterly between T1 and T2. Other measures included age, gender, VO(2 max) obtained from maximal treadmill testing, body mass index (BMI), and body fat percentage.

RESULTS

Multiple regression demonstrated that mean NAS, T1 weight, aging and gender all influence long-term T2 weight. T1 age was significant for the men only. Independently, each increase in mean NAS significantly (P<0.01) reduced T2 weight in men (b=-0.91 kg; 95% CI:-1.4 to-0.42 kg) and women (b=-2.14 kg; 95% CI:-2.93 to-1.35 kg). Mean NAS had a greater effect on T2 weight as T1 weight increased, and the relationship was dose-dependent.

CONCLUSIONS

Habitual physical activity is a significant source of long-term weight change. The use of self-reported activity level is helpful in predicting long-term weight changes and may be used by health care professionals when counseling patients about the value of physical activity for weight control.

Development of normative values for resting and exercise rate pressure product

PURPOSE

The purpose of this study was to develop multivariate models to quantify resting, submaximal, and maximal rate pressure products (RPP).

METHODS

A validation sample (N = 1623) was randomly selected from a clinically healthy population, and four cross-validation samples were randomly selected from a clinical cohort. The cross-validation samples were patients who had a negative exercise ECG with (Neg-Med, N = 179) and without cardiovascular drug (Neg-NoMed, N = 350), and patients who had a positive exercise ECG with (Pos-Med, N = 60) and without cardiovascular drug (Pos-NoMed, N = 75). Men made up 83% of the validation sample (mean age = 44.2+/-8.7) and women 17% (mean age = 39.7+/-10.1). The validation sample was used to develop multiple regression equations to quantify resting, submaximal, and maximal RPP.

RESULTS

Results indicated that gender, body mass index (BMI), and physical activity level (Ex-code) were significantly related with resting RPP. Gender, age, BMI, and Ex-code were significantly related with maximal RPP. Gender, age, BMI, Ex-code, and percent of maximal heart rate at submaximal exercise (%HRmax) were significantly related with submaximal RPP. The multiple correlations for the resting, submaximal, and maximal models were 0.29 (SE = 16.75 beats x min(-1) x mm Hg), 0.87 (SE = 29.04 beats x min(-1) x mm Hg), and 0.31 (SE = 42.41 beats x min(-1) x mm Hg), respectively. The accuracy of the models was confirmed when applied to the Neg-NoMed and Pos-NoMed samples but not the Neg-Med and Pos-Med samples. This result suggest that the regression models developed from this study can be generalized to other populations where patients were not taking cardiovascular medication. Microcomputer programs were suggested to evaluate RPP at rest, maximal exercise, and submaximal exercise.

CONCLUSION

Normative RPP for resting and exercise relies on multiple fitness parameters. Practical regression models are developed and can be applied to patients without cardiovascular medication.

Modeling the influence of body size on V(O2) peak: effects of model choice and body composition

This study examined the bivariate relationship between peak oxygen uptake (V(O2) peak); l/min) and body size in adult men (n = 1,314, age 17-66 yr), using both "simple" and "full" iterative nonlinear allometric models. The simple model was described by V(O2) peak = M(b) (or FFM(b)) exp(c SR-PA) exp(a + d age) epsilon (where M is body mass in kg; FFM is fat-free mass in kg; SR-PA is self-reported physical activity; epsilon is a multiplicative error term; and exp indicates natural antilogarithms). The full model was described by V(O2) peak = M(b) (or FFM(b)) exp(c SR-PA) exp(a + d age) + e (epsilon), where e is a permitted Y-intercept term. The M exponent obtained from simple allometry was 0.65 [95% confidence interval (CI), 0.59-0.71], suggestive of a curvilinear relationship constrained to pass through the origin. This "zero Y-intercept" assumption was examined via the full allometric model, which revealed an M exponent of 1.00 (95% CI, 0.7-1.31), together with a positive Y-intercept term (e) of 1.13 (95% CI, 0.54-1.73). The FFM exponents were not significantly different from unity in either the simple or full allometric models. It appears that the curvilinearity of the simple allometric model (using total M) is fictitious and is due to the inappropriate forcing of the regression line through the origin. Utilizing FFM as the body-size variable revealed a linear relationship between body size and V(O2) peak, irrespective of model choice. We conclude that the population mass exponent for V(O2) peak is close to unity.

Early identification of Mexican American children who are at risk for becoming obese

OBJECTIVE

To describe the problem of obesity in Mexican American children and provide a method for identifying Mexican American children at risk for obesity.

DESIGN

Cross-sectional and retrospective cohort study.

SUBJECTS

Mexican American children, ages 5-11 (kindergarten (K)-5th grade) were studied in cross-sectional (girls = 463, boys = 448) and retrospective (girls = 124, boys = 92) samples.

MEASUREMENTS

Weights (kg) and heights (cm) were extracted from each child's school medical records. Measurements were made by the school nurses (one nurse per school). Body mass index (BMI [w/h2]) was calculated from obtained weights and heights.

RESULTS

The prevalence of obesity in the cross-sectional sample was 27.4% for girls and 23.0% for boys. The highest prevalence was noted in 4th grade for both the girls (32.4%) and boys (43.4%). The 5 year incidence rates derived from the retrospective sample were 17.7% for girls and 21.1% for boys. The largest increase in the number of girls becoming obese was observed between K and 1st grade (15.6%). The largest increase for boys was found between the 1st and 2nd grades (13.2%). Logistic regression parameters were calculated to estimate the probability of becoming obese in 5th grade given a child's K BMI. Using the generated equation, BMIs in K equal to 16.5, 20.9, and 23.7 would have a 21.0%, 70.0%, and 91.0% probability of being obese by 5th grade.

CONCLUSION

This study provides schools with a simple procedure for identifying Mexican American children at risk for obesity. This procedure may assist in the development and implementation of interventions aimed at averting the onset of obesity in this population.

Cardiorespiratory fitness, body composition, and all-cause and cardiovascular disease mortality in men

BACKGROUND

Cardiorespiratory fitness and body fatness are both related to health, but their interrelation to all-cause and cardiovascular disease (CVD) mortality is unknown.

OBJECTIVE

We examined the health benefits of leanness and the hazards of obesity while simultaneously considering cardiorespiratory fitness.

DESIGN

This was an observational cohort study. We followed 21925 men, aged 30-83 y, who had a body-composition assessment and a maximal treadmill exercise test. There were 428 deaths (144 from CVD, 143 from cancer, and 141 from other causes) in an average of 8 y of follow-up (176742 man-years).

RESULTS

After adjustment for age, examination year, cigarette smoking, alcohol intake, and parental history of ischemic heart disease, unfit (low cardiorespiratory fitness as determined by maximal exercise testing), lean men had double the risk of all-cause mortality of fit, lean men (relative risk: 2.07; 95% CI: 1.16, 3.69; P = 0.01). Unfit, lean men also had a higher risk of all-cause and CVD mortality than did men who were fit and obese. We observed similar results for fat and fat-free mass in relation to mortality. Unfit men had a higher risk of all-cause and CVD mortality than did fit men in all fat and fat-free mass categories. Similarly, unfit men with low waist girths (<87 cm) had greater risk of all-cause mortality than did fit men with high waist girths (> or =99 cm).

CONCLUSIONS

The health benefits of leanness are limited to fit men, and being fit may reduce the hazards of obesity.

The energy cost of horizontal walking and running in adolescents

PURPOSE

This study developed and cross-validated generalized equations for predicting VO2 (mL x kg(-1) x min(-1)) and caloric expenditure (kcal x kg(-1) x min(-1)) during horizontal walking and running in adolescents.

METHODS

Subjects were 47 male and 35 female adolescent volunteers, ages 12-18. Each subject underwent a submaximal treadmill exercise test to determine VO2 at randomly selected walking and jogging speeds (67-215 m x min(-1)). Caloric expenditure was estimated from VO2 and RER. Multiple regression was used to develop prediction equations for estimating VO2 and caloric expenditure from a derivation sample of 77 random observations, both walking and running.

RESULTS

The group relationship between running speed and energy cost in the derivation sample was linear, whereas the relationship between walking speed and energy cost was quadratic. Gender, age, and height each failed to account for significant additional variation in energy cost after speed and mode were considered. Skinfolds accounted for a small yet significant amount of additional variation in energy cost. The derived equations were cross-validated on a sample of 76 separate random observations. The cross-validation statistics are: for VO2, R = 0.95, error = 3.58 mL x kg(-1) x min(-1), and for caloric expenditure, R = 0.94, error = 0.019 kcal x kg(-1) x min(-1). Most selected adult equations consistently underestimated both VO2 and caloric expenditure in the cross-validation sample.

CONCLUSIONS

These results suggest that in adolescents, within the range of speeds tested, the relationship between speed of movement and energy cost for running is linear, but for walking is curvilinear. Also, adult models for estimating VO2 or caloric expenditure do not account for the higher relative energy cost of walking and running in adolescents.

US weight guidelines: is it also important to consider cardiorespiratory fitness?

BACKGROUND

The health consequences of weight ranges across low to moderate and high levels of cardiorespiratory fitness are unknown.

OBJECTIVE

To evaluate the validity of the 1995 US weight guidelines, while considering cardiorespiratory fitness.

METHODS

We followed 21,856 men, aged 30-83 y, who had a complete preventive medical examination, including a maximal treadmill exercise test and body composition assessment. There were 427 deaths (144 cardiovascular disease (CVD); 143 cancer; 140 others) during an average of 8.1 y of follow-up. We used Cox proportional hazards regression to examine the relations among cardiorespiratory fitness, body mass index (BMI, kg/m2), and all-cause and CVD mortality.

RESULTS

After adjustment for age, examination year, cigarette smoking and alcohol intake, we observed that men with a BMI of 19.0 to < 25.0 and who were unfit had 2.3 times the risk of all-cause mortality (95% confidence interval (95% CI), 1.59-3.17, P < 0.001) compared with fit men in this BMI group (reference category). Unfit men with a BMI of 25.0 to < 27.8 also had a greater risk of all-cause mortality than fit men in the same BMI category. Fit but overweight men (BMI > or = 27.8) had a similar rate of all-cause mortality as physically fit men of normal weight (BMI 19.0 to < 25.0) and had a lower risk of all-cause mortality than unfit and normal weight men. Fit men of normal weight had the lowest CVD mortality, while unfit and overweight men experienced the highest CVD mortality. Unfit men had substantially higher CVD mortality than fit men in each BMI group.

CONCLUSIONS

Unfit men had higher all-cause and CVD mortality than fit men. The health benefits of normal weights appear to be limited to men who have moderate or high levels of cardiorespiratory fitness. These data suggest that the 1995 US weight guidelines may be misleading unless cardiorespiratory fitness is taken into account.

Changes in aerobic power of women, ages 20-64 yr

This study quantified and compared the cross-sectional and longitudinal influence of age, self-report physical activity (SR-PA), and body composition (%fat) on the decline of maximal aerobic power (VO2peak) of women. The cross-sectional sample consisted of 409 healthy women, ages 20-64 yr. The 43 women of the longitudinal sample were from the same population and examined twice, the mean time between tests was 3.7 (+/-2.2) yr. Peak oxygen uptake was determined by indirect calorimetry during a maximal treadmill test. The zero-order correlation of -0.742 between VO2peak and %fat was significantly (P < 0.05) higher then the SR-PA (r = 0.626) and age correlations (r = -0.633). Linear regression defined the cross-sectional age-related decline in VO2peak at 0.537 ml.kg-1.min-1.yr-1. Multiple regression analysis (R = 0.851) showed that adding %fat and SR-PA and their interaction to the regression model reduced the age regression weight of -0.537, to -0.265 ml.kg-1.min-1.yr-1. Statistically controlling for time differences between tests, general linear models analysis showed that longitudinal changes in aerobic power were due to independent changes in %fat and SR-PA, confirming the cross-sectional results. These findings are consistent with men's data from the same lab showing that about 50% of the cross-sectional age-related decline in VO2peak was due to %fat and SR-PA.

Methods and limitations of assessing functional work capacity objectively

This paper examined the methods and issues of assessing objectively the functional capacity of workers. The primary emphasis was on aerobic capacity (VO2max ) and repetitive lifting. While the direct measurement of expired gases during exhausting exercise is the most valid method of assessing the VO2max  of workers, it is rarely done outside research or medical settings. The methods more commonly used are: maximal exercise tests; submaximal exercise tests; and non-exercise tests. Maximal tests are accurate, but require medical monitoring when testing workers at medical risk. Submaximal tests are less accurate, but are safer and faster than a maximal test. Submaximal tests use heart rate response to submaximal power output to estimate VO2max ; thus, any factor that alters heart rate response reduces the accuracy of the test. Non-exercise tests are as accurate as sub maximal tests, but require a self-report rating. The physiological criteria used to help define the recommended repetitive lift loads of the revised NIOSH equation included baseline aerobic capacity and energy expenditure values. While the goal is to reduce the risk of injury, the baseline aerobic capacity (≈ 25 ml/kg/min) and energy expenditure levels are so low (≤3.5 METs) that they may have an adverse effect on public health. Normative VO2max  data on industrial cohorts suggest that 44% of male and 79% of female industrial workers are at a health risk of low aerobic fitness. Data are presented that suggests that repetitive lifting tasks are more of a function of strength and fat-free weight than aerobic capacity. While aerobic capacity, strength, and fat-free weight are objective methods to assess functional capacity, worker motivation and reaction to chronic pain can affect test results.

Relationships between the Body Mass Index and body composition

The aims of this study were to evaluate the Body Mass Index (BMI) (weight/stature2) as a proxy for percent body fat (%BF) and to determine its association with fat-free mass (FFM). Multivariate analysis of variance and partial correlations were used to examine relationships between BMI and %BF and FFM from densitometry for 504 men and 511 women, aged 20 to 45 years. Sensitivity/specificity analyses used cut offs of 28 kg/m2 in men and 26 kg/m2 in women for BMI, and 25% in men and 33% in women for %BF. Significantly higher associations existed in each gender between BMI and %BF in the upper BMI tertile than in the lower BMI tertiles. In the lower BMI tertiles, correlations between BMI and FFM were approximately twice as large as those between BMI and %BF. The BMI correctly identified about 44% of obese men, and 52% of obese women when obesity was determined from %BF. BMI is an uncertain diagnostic index of obesity. Results of Receiver Operator Characteristic (ROC) analyses using %BF and total body fat, both provided a BMI of 25 kg/m2 in men and 23 kg/m2 in women as diagnostic screening cut offs for obesity.

Changes in aerobic power of men, ages 25-70 yr

This study quantified and compared the cross-sectional and longitudinal influence of age, self-report physical activity (SR-PA), and body composition (%fat) on the decline of maximal aerobic power (VO2peak). The cross-sectional sample consisted of 1,499 healthy men ages 25-70 yr. The 156 men of the longitudinal sample were from the same population and examined twice, the mean time between tests was 4.1 (+/- 1.2) yr. Peak oxygen uptake was determined by indirect calorimetry during a maximal treadmill exercise test. The zero-order correlations between VO2peak and %fat (r = -0.62) and SR-PA (r = 0.58) were significantly (P < 0.05) higher that the age correlation (r = -0.45). Linear regression defined the cross-sectional age-related decline in VO2peak at 0.46 ml.kg-1.min-1.yr-1. Multiple regression analysis (R = 0.79) showed that nearly 50% of this cross-sectional decline was due to %fat and SR-PA, adding these lifestyle variables to the multiple regression model reduced the age regression weight to -0.26 ml.kg-1.min-1.yr-1. Statistically controlling for time differences between tests, general linear models analysis showed that longitudinal changes in aerobic power were due to independent changes in %fat and SR-PA, confirming the cross-sectional results.

Validation of a 20-minute steady-state jog as an estimate of peak oxygen uptake in adolescents

Distance run tests are often used to estimate peak oxygen uptake (peak VO2) in children. This study examined the concurrent validity of a 20-min steady-state jog (20MSSJ). The sample consisted of 43 boys and 32 girls who performed a 20MSSJ and completed a maximal treadmill test 1 week later. Peak VO2 was measured by indirect calorimetry. Subject characteristics were as follows: boys, mean age = 15.1 +/- 1.0 years, mean peak VO2 = 46.4 +/- 7.7 ml.kg-1 x min-1, mean 20MSSJ = 2.3 +/- 0.5 miles; girls, mean age = 15.3 +/- 1.1 years, mean peak VO2 = 40.4 +/- 5.1 ml.kg-1 x min-1, mean 20MSSJ = 2.1 +/- 0.5 miles. The correlation between 20MSSJ and peak VO2 was .68 across boys and girls. The regression slopes of the boys and girls were common, but the intercepts differed, F (1, 72) = 10.9, p < .05. The influence of weight and skinfold fat was examined. Separate models were developed, and the R for each was increased to .79 (SEE = 4.45 ml.kg-1 x min-1) for the model using weight and .80 (SEE = 4.36 ml.kg-1 x min-1) for the model using sum of skinfolds. The regression equations are as follows: peak VO2 = 35.10 + 6.19 (Run) + 2.96 (Gender) -0.26 (Skinfold fat) peak VO2 = 33.94 + 7.64 (Run) + 5.84 (Gender) -0.18 (Weight) (Run = 20MSSJ performance in miles; Gender; females = 0, males = 1; Skinfold fat = sum of two-site skinfolds in mm; Weight = body weight in kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Psychological profile of college students who use smokeless tobacco

The purpose of this study was to develop a psychological profile of smokeless tobacco users. We surveyed 1991 college students regarding their use of tobacco products. Twenty-one percent of the white males used smokeless tobacco compared to only 10.4% of blacks, 5.4% of Hispanics, and 5.4% of others, primarily Asians. Although the prevalence of smokeless tobacco use reported by Asians was relatively low, their rate of reported smoking was over twice as high as any other ethnic group, 43.6%. The most important reasons for beginning to use smokeless tobacco were to "see if I would enjoy it," "most friends used it," and "try something new." The personality profile of the smokeless tobacco users differed from that of smokers and non-users of tobacco. College students with the highest probability of being a smokeless tobacco user were white males who scored higher in extraversion and neuroticism but lower on state anxiety than non-users.

Prediction of functional aerobic capacity without exercise testing

The purpose of this study was to develop functional aerobic capacity prediction models without using exercise tests (N-Ex) and to compare the accuracy with Astrand single-stage submaximal prediction methods. The data of 2,009 subjects (9.7% female) were randomly divided into validation (N = 1,543) and cross-validation (N = 466) samples. The validation sample was used to develop two N-Ex models to estimate VO2peak. Gender, age, body composition, and self-report activity were used to develop two N-Ex prediction models. One model estimated percent fat from skinfolds (N-Ex %fat) and the other used body mass index (N-Ex BMI) to represent body composition. The multiple correlations for the developed models were R = 0.81 (SE = 5.3 ml.kg-1.min-1) and R = 0.78 (SE = 5.6 ml.kg-1.min-1). This accuracy was confirmed when applied to the cross-validation sample. The N-Ex models were more accurate than what was obtained from VO2peak estimated from the Astrand prediction models. The SEs of the Astrand models ranged from 5.5-9.7 ml.kg-1.min-1. The N-Ex models were cross-validated on 59 men on hypertensive medication and 71 men who were found to have a positive exercise ECG. The SEs of the N-Ex models ranged from 4.6-5.4 ml.kg-1.min-1 with these subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the NASA/JSC Health Related Fitness Program

This study evaluated the long-term effects of the NASA/Johnson Space Center Health Related Fitness Program (HRFP) which includes a 12-week educational component (EC) and quarterly fitness retests (RT). The groups studied were: Compliers (completed EC and greater than or equal to 75% of RT, N = 64); Non-compliers (completed EC but less than 75% of RT, N = 106); Drop-outs (disenrolled from EC, N = 36) and Controls (randomly selected from eligible program pool, N = 52). Pretest medical examination and maximum stress test data showed the groups did not differ on age, % fat, weight, blood lipids, and VO2max (p greater than 0.05). Multivariate analysis of pre- and posttest change data greater than or equal to 2 years from start showed group differences in blood lipids, body composition and VO2max. Results showed that changes in physical activity were related to program completion and periodic fitness reevaluations, and that these group-related changes were associated with changes in VO2max, percent body fat, body weight, and blood lipids.

Enkephalin metabolism: effect of acute exercise stress and cardiovascular fitness

Inhibition of enkephalin hydrolysis by catecholamines in vitro suggested that local and/or humoral factors released during exercise might facilitate opiate responses by reducing the rate of opiate peptide inactivation. Several measures of enkephalin hydrolysis were determined in blood samples obtained from subjects designated as trained (VO2max, 64.3 +/- 1.6 ml.min-1.kg-1) and un-trained (VO2max, 37.4 +/- ml.min-1.kg-1) both at rest and after maximal exercise stress tests. Enkephalin hydrolyzing activity assessed under optimal conditions was equally distributed between plasma and intact red cells; however, hydrolysis by red cells increased dramatically following osmotic release of red cell contents. There were no apparent differences in enzyme concentration or its distribution between cells and plasma when comparing trained and untrained subjects; P greater than 0.05. There was also no statistical effect of maximal exercise on these measures in either group. However, when the sequential disappearance of enkephalin added to whole blood in vitro was evaluated, blood from trained subjects degraded the enkephalin more slowly than blood from untrained subjects and had half-lives in vitro 30-50% longer both before and after the exercise test; P less than 0.05. Since enzyme concentrations between the groups were similar, the longer half-lives suggest that circulating factors were responsible for moderating the rate of enkephalin metabolism in vivo and that these factors were more concentrated in trained subjects. This would facilitate opiate responses in trained subjects and perhaps provide them with added tolerance for the effort associated with elite performance levels.

Reliability and validity of bioelectrical impedance in determining body composition

This study was designed to examine the reliability and validity of the bioelectrical impedance method (BIA) of measuring body composition and compare its accuracy with the results obtained by standard anthropometric methods BIA, skinfold fat, and hydrostatically measured percent fat (% fat) were obtained on 44 women and 24 men. Each subject was tested four times by two testers on two different days. Generalizability theory was used to estimate reliability and measurement error that considered both day-to-day and intertester error. The BIA, skinfold fat, and hydrostatic methods were all found to be reliable (Rxx = 0.957-0.987) with standard errors ranging from 0.9 to 1.5% fat. An additional 26 men (n = 50) and 38 women (n = 82) were tested once and combined with the data used for the reliability analysis to cross-validate BIA estimates of % fat with hydrostatically determined % fat. The cross-validation correlations for the BIA determinations of % fat ranged from 0.71 to 0.76, which were significantly lower than that obtained with the sum of seven (sigma 7) skinfolds equations (rxy = 0.92 for men and 0.88 for women). The correlations between the weight-to-height ratio body mass index (BMI) and hydrostatically determined % fat were 0.75 and 0.74 for men and women, respectively. The standard errors of estimate for the two BIA models ranged from 4.6 to 6.4% fat compared with 2.6 and 3.6% fat for the sigma 7 equations. The BIA method for measuring body composition was comparable to the BMI method, with height and weight accounting for most of the variance in the BIA equation.

The effect of hand-held weights on the physiological responses to walking exercise

To study the physiological responses to walking with hand-held weights (HWs), 12 untrained men completed three sub-maximal and two maximal treadmill tests. Heart rate, oxygen uptake, respiratory exchange ratio, ventilation, systolic blood pressure (BP), diastolic BP, rate pressure product, and rating of perceived exertion were significantly greater (P less than 0.01) when HWs were added to walking exercise performed at constant treadmill speed and grade. To evaluate whether the evaluated BP response was caused by HWs independent of exercise load, heart rate was held constant at 75% maximum heart rate reserve during the third submaximal test. Systolic BP (151.1 +/- 15.3 mm Hg vs 160.1 +/- 16.9 mm Hg) and rate pressure product (252.1 +/- 27.0 vs 237.3 +/- 25.1) were significantly greater (P less than 0.05) during exercise with HWs. Physiological responses to maximal exercise with and without 3 lb HWs were similar. The time to exhaustion, however, was reduced (P less than 0.01) with HWs. (719.3 +/- 98.1 s with HWs vs 784.4 +/- 118.9 s without HWs). These data indicate that 3-lb HWs can increase the metabolic cost of training (1 MET, 7 to 13 b X min-1) and may be useful in exercise prescription for individuals who do not want to run or are limited in the speed at which they can walk. Due to the exaggerated BP response, caution should be used when prescribing HW exercise for patients where increasing afterload may be a problem.

Accuracy of measured and predicted residual lung volume on body density measurement

The effects of measured and predicted residual lung volume on the accuracy of body density and percent fat (%Fat) were investigated. Adult fitness subjects (N = 46) had residual lung volume measured with the oxygen dilution method while those from an athlete sample (N = 134) utilized the nitrogen washout technique. Residual lung volume was also predicted with gender-specific regression equations using height and age and from 24% of vital capacity (%FVC). Residual lung volume alpha reliability for the average of four residual lung volume trials exceeded 0.90 (SEM less than = 161 ml) for the oxygen dilution method and 0.99 (SEM = 30 ml) for the average of two nitrogen washout measures. The standard errors for predicted residual lung volume were 579 and 355 ml, respectively, for the men and women in the adult sample and 288 ml for the trained athlete sample. Estimating residual lung volume from %FVC yielded a SEE of 318 ml for the trained athlete sample. Measured residual lung volume errors resulted in errors of 1.04%Fat, 0.87%Fat, and 0.21%Fat for the men, women, and trained athlete samples, respectively. In contrast, predicted residual lung volume measurement errors resulted in errors of 3.70%Fat, 2.85%Fat, and 1.98%Fat for the respective samples and 2.18%Fat when using %FVC with the trained athletes. Measured residual lung volume introduces little %Fat error while predicted residual lung volume introduces a substantial source of measurement error.

Practical Assessment of Body Composition

In brief: The assessment of body composition has become an important method for determining a desirable body weight of adults and athletes. Hydrostatic weighing is a popular and valid method, but it is often not feasible for the clinical setting or for mass testing; thus, anthropometry has become the preferred method. This article reviews the scientific basis for generalized body composition prediction equations and provides methods for evaluating body composition. The authors recommend using a sum of three skinfolds (triceps, chest, and subscapula for men and triceps, abdomen, and suprailium for women) and give detailed instructions for securing accurate measurements of body fat.

Research design and analysis of data procedures for predicting body density

Statistical methods used to develop body composition prediction equations were examined. Equations published in the 1960s and early 1970s have been called "population-specific" equations because they were developed on homogeneous samples. A major limitation of population-specific equations was a low ratio of subjects per variable, which reduces validity. The more recent method has been to develop "generalized" equations with large samples varying greatly in age and body fatness. The statistical models used for generalized equations were nonlinear regression analysis to account for the quadratic relation between body density and skinfold fat. Age was used as an independent variable to adjust for aging. Generalized equations exhibit accuracy consistent with population-specific equations and increase the generalizability of prediction. Future body composition research should focus on the cross-validation of published equations to define the limits of equation accuracy.

Research progress in validation of clinical methods of assessing body composition

Anthropometry is the method of choice for estimating body composition in the clinical setting. The method can be accurate, and requires little time, space, equipment, or financial outlay. Although used extensively in epidemiological research, height/weight indices are not as accurate as skinfold and circumference measures for estimating body composition. The validity of estimating body density is enhanced by using a combination of skin-fold and circumference measures in a multiple-regression model. Some recently developed generalized equations may have a broader application for use in varied populations than several population-specific equations. The newer equations take into account the potential change in ratio of internal to external fat and bone density with age, and the nonlinear relationship between skinfold fat and body density. The validity of using skinfolds for estimating body density can be significantly affected by caliper selection and measurement procedures. Inter-observer errors appear to be the most problematic, with improper skinfold site selection causing the greatest variation among observers. To improve the validity of the anthropometric technique for use in the clinical setting, more precise standards and description of methods need to be developed.

Comparison of exercise blood pressure measured by technician and an automated system

We evaluated the automated system Blood Pressure Measuring System (BPMS) developed by NASA on 277 adult males who elected to have a treadmill test as part of their annual physical. The BPMS uses acoustic transduction with a computer-assisted ECG gating to detect nonsynchronous noise. The BPMS readings were compared to pressures simultaneously measured by trained technicians. For all stages of work, BPMS readings were higher for systolic and lower for diastolic than technician readings. At peak stages of work, BPMS systolic pressures were about 20 mmHg higher than technician readings. Within each 3-min workstage, BPMS readings were found to be more inconsistent than technician readings. The standard errors of measurement for BPMS were from two to three times higher than technician values. These data showed automated blood pressure readings were significantly different than technician values and subject to more random fluctuations. These findings demonstrate the need to view exercise blood pressure measured by automated systems with caution.

Hemodynamic effects of oral smokeless tobacco in dogs and young adults

Oral smokeless tobacco (snuff) is increasingly used among the young male population. To determine cardiovascular effects of an oral smokeless tobacco product, 10 anesthetized dogs were instrumented to measure blood pressure, heart rate, left ventricular end diastolic pressure, and circumflex coronary, renal, and femoral flows. After a 5-min baseline, a 2.5-g, approximately 1.2% nicotine bolus dose was placed in the buccal space, and measurements were made for 20 min. Significant increases were seen in heart rate, blood pressure, left ventricular pressure, left ventricular end diastolic pressure, and left ventricular dP/dt. Significant decreases in flow were noted in the coronary circumflex, renal, and femoral arteries. The flow reduction was thought to have been mediated by an alpha-adrenergic mechanism. Additionally, 20 human males, mean age 20 years, without nicotine exposure for 72 hr, were given a 2.5-g dose of the same oral smokeless product. From baseline to 20 min, heart rate increased from 69 to 88 beats/min (P less than 0.05), blood pressure from 118/72 to 126/78 mm Hg (P less than 0.05). Thus, oral smokeless tobacco use can produce significant hemodynamic changes in both dogs and normal humans.

Steps toward the development of generalized equations for predicting body composition of adults

The estimation of body density from anthropometric variables is often used to measure body composition. The purpose of this report was to review the development of early published equations and follow the transition from population specific equations to generalized equations for adults. The accuracy of population specific equations were improved and refined with the addition of circumference and diameter measures in combination with skinfolds and the use of populations of varied ages and degrees of body fatness. The major weakness of the population specific equations was their inability to account for aging and the non linear relationship between subcutaneous fat and body density. Regression models using the quadratic sum of skinfolds and age have been developed to account for these sources of variation. Cross-validation research has shown that these generalized regression models are accurate for adult males and females varying greatly in age and body fatness.

Evaluation of the NASA/JSC blood pressure screening clinic

This study evaluated the NASA/Johnson Space Center's blood pressure screening program, which was designed to identify the proportion of NASA employees who were hypertensive and to identify self-report variables related to elevated pressures. In 1978, a random sample of 3892 employees was selected from over 2,100 NASA employees. Twenty-eight percent were classified as hypertensive by the criterion of systolic pressure of 140 or above or diastolic pressure of 90 or greater. Approximately 16% of all employees had a history of hypertension; the remaining 12% of the identified hypertensives were unaware of their potential health problem. Multivariate analysis showed that elevated systolic pressures were more prevalent in the older, heavier employees. Of hypertensives under treatment, about 74% were under poor control as judged from blood pressures randomly taken at their place of employment. These results demonstrated the effectiveness of screening for unsuspecting hypertensives in industry.

Fitness variables and the lipid profile in United States astronauts

The study examines the relationship between several measures of fitness and the lipid profile in United States astronauts. Data were collected on 89 astronauts, previously selected (PSA) and newly selected (NSA), during their annual physical examinations. Several similarities were seen in the two groups. The PSA (mean age of 46.1) had a lower maximum VO2 (41.7 ml . mg . min-1 vs. 47.5 ml . kg . min-1); when adjusted for age, it was no different from the NSA (mean age 33.5). The PSA had similar body composition with 15.7%--lower than expected for age. The lipid profiles of the two groups were basically the same with the differences being a function of age. Compared to a normative population, the astronauts had similar cholesterols, lower triglycerides, and higher HDLs. The astronaut profiles were generally more favorable than the age-matched controls, which is felt to be a result of the self-supervised conditioning program and annual preventive medicine consultation and education.

Generalized equations for predicting body density of women

Previous research with women has shown that body composition regression equations derived from anthropometric variables were population specific. This study sought to derive generalized equations for women differing in age and body composition. The hydrostatic method was used to determine body density (BD) and percent fat (%F) on 249 women in 18 to 55 years (X = 31.4 +/- 10.8 yrs) and 4 to 44 %F (X = 24.1 +/-7.2 %F). Skinfold fat (S), gluteal circumference (C) and age were independent variables. The quadratic form of the sum of three, four and seven S in combination with age and gluteal C produced multiple correlations that ranged from 0.842 to 0.867 with standard errors of 3.6 to 3.8 %F. The equations were cross-validated on a different sample of 82 women with similar age and %F characteristics. The correlations between predicted and hydrostatically determined %F ranged from 0.815 to 0.820 with standard errors of 3.7 to 4.0 %F. This study showed that valid generalized body composition equations could be derived for women varying in age and body composition, but care need to be exercised with women over an age of forty.