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Biomedical subjects

S N Blair

Publications and source records attributed to S N Blair.

At least 19 recordsLinked to original sources

Osteoarthritis: new insights. Part 2: treatment approaches.

Osteoarthritis is the most common form of arthritis, affecting millions of people in the United States. It is a complex disease whose etiology bridges biomechanics and biochemistry. Evidence is growing for the role of systemic factors, such as genetics, diet, estrogen use, and bone density, and local biomechanical factors, such as muscle weakness, obesity, and joint laxity. These risk factors are particularly important in the weight-bearing joints, and modifying them may help prevent osteoarthritis-related pain and disability. Major advances in management to reduce pain and disability are yielding a panoply of available treatments ranging from nutriceuticals to chondrocyte transplantation, new oral anti-inflammatory medications, and health education. This article is part 2 of a two-part summary of a National Institutes of Health conference that brought together experts in osteoarthritis from diverse backgrounds and provided a multidisciplinary and comprehensive summary of recent advances in the prevention of osteoarthritis onset, progression, and disability. Part 2 focuses on treatment approaches; evidence for the efficacy of commonly used oral therapies is reviewed and information on alternative therapies, including nutriceuticals and acupuncture, is presented. Biomechanical interventions, such as exercise and bracing, and behavioral interventions directed toward enhancing self-management are reviewed. Current surgical approaches are described and probable future biotechnology-oriented approaches to treatment are suggested.

Acupuncture Therapy↗

Maximal exercise test as a predictor of risk for mortality from coronary heart disease in asymptomatic men.

Exercise testing in asymptomatic persons has been criticized for failing to accurately predict those at risk for coronary heart disease (CHD). Previous studies on asymptomatic subjects, however, may not have been large enough or long enough to provide reliable outcome measures. This study examines the ability of a maximal exercise test to predict death from CHD and death from any cause in a population of asymptomatic men. This is a prospective longitudinal study performed between 1970 and 1989, with an average follow-up of 8.4 years. The subjects are 25,927 healthy men, 20 to 82 years of age at baseline (mean 42.9 years) who were free of cardiovascular disease and who were evaluated in a preventive medicine clinic. The main outcome measures are CHD mortality and all-cause mortality. During follow-up there were 612 deaths from all causes and 158 deaths from CHD. The sensitivity of an abnormal exercise test to predict coronary death was 61%. The age-adjusted relative risk of an abnormal exercise test for CHD death was 21 (6.9 to 63.3) in those with no risk factors, 27 (10.7 to 68.8) in those with 1 risk factor, 54 (21.5 to 133.7) in those with 2 risk factors, and 80 (30.0 to 212. 5) in those with >/=3 factors. A maximal exercise test performed in asymptomatic men free of cardiovascular disease does appear to be a worthwhile tool in predicting future risk of CHD death. An abnormal exercise test is a more powerful predictor of risk in those with than without conventional risk factors.

Adult↗

Incremental reduction of serum total cholesterol and low-density lipoprotein cholesterol with the addition of plant stanol ester-containing spread to statin therapy.

This study compares the effect of plant stanol ester spread with a placebo spread on cholesterol in patients taking statin therapy, but who still had elevated low-density lipoprotein (LDL) cholesterol. This was a randomized, double-blind, placebo-controlled clinical trial, with 67 women and 100 men with LDL cholesterol >/=130 mg/dl and triglycerides </=350 mg/dl who had been taking a stable dose of a statin drug for at least 90 days before the start of the study. For 8 weeks, participants consumed 3 servings/day of the plant stanol ester spread that provided 5.1 g/day of plant stanol ester or a placebo. The addition of plant stanol ester spread significantly reduced total cholesterol and LDL cholesterol at 2, 4, and 8 weeks when compared with placebo spread. Plant stanol ester spread reduced total cholesterol at 8 weeks by 12% compared with a placebo reduction of 5% (-7% difference; p <0.0001). Plant stanol ester spread reduced LDL cholesterol at 8 weeks by 17% compared with a 7% reduction in the placebo group (-10% difference, p <0.0001). The absolute reduction in LDL cholesterol at 8 weeks was 24 and 10 mg/dl in the stanol ester and placebo groups, respectively. The plant stanol ester spread group also had greater reductions in both serum total cholesterol and LDL cholesterol than the placebo group at 2 and 4 weeks (p <0.001 for all comparisons). Both spreads were well tolerated by study participants, and no significant adverse events were noted. Consumption of spread that provided 5.1 g/day of plant stanol esters effectively reduced elevated total and LDL cholesterol levels in participants on a stable regimen of a statin.

Administration, Oral↗

Low fasting plasma glucose level as a predictor of cardiovascular disease and all-cause mortality.

BACKGROUND: Although medical textbooks usually classify fasting plasma glucose <70 or 80 mg/dL (<3.89 or 4.44 mmol/L) as abnormal, the prognosis for patients with low fasting plasma glucose is unclear. METHODS AND RESULTS: We conducted prospective cohort studies among 40 069 men and women to investigate the association between fasting plasma glucose levels and cardiovascular disease and all-cause mortality. We documented a U-shaped relation between fasting plasma glucose and mortality. In addition to diabetes and impaired fasting glucose levels, low fasting plasma glucose levels were also associated with high mortality. After multivariate adjustment for age, sex, study population, ethnicity, current smoking status, high blood pressure, total cholesterol, body mass index, triglycerides, history of cardiovascular disease and cancer, and a family history of cardiovascular disease, patients with fasting plasma glucose <70 mg/dL (<3.89 mmol/L) had a 3.3-fold increased risk of cardiovascular disease mortality, and patients with fasting plasma glucose 70 to 79 mg/dL (3.89 to 4.43 mmol/L) had a 2.4-fold increased risk compared with the risk in patients with fasting plasma glucose 80 to 109 mg/dL (4.44 to 6.05 mmol/L) (tests for trend P<0.0001). Participants with low fasting plasma glucose levels also had increased risk of all-cause mortality (test for trend P<0.0001). CONCLUSIONS: Participants with low fasting plasma glucose levels had a high risk of cardiovascular disease and all-cause mortality.

Adult↗

Low cardiorespiratory fitness and physical inactivity as predictors of mortality in men with type 2 diabetes.

BACKGROUND: Although physical activity is recommended as a basic treatment for patients with diabetes, its long-term association with mortality in these patients is unknown. OBJECTIVE: To evaluate the association of low cardiorespiratory fitness and physical inactivity with mortality in men with type 2 diabetes. DESIGN: Prospective cohort study. SETTING: Preventive medicine clinic. PATIENTS: 1263 men (50+/-10 years of age) with type 2 diabetes who received a thorough medical examination between 1970 and 1993 and were followed for mortality up to 31 December 1994. MEASUREMENTS: Cardiorespiratory fitness measured by a maximal exercise test, self-reported physical inactivity at baseline, and subsequent death determined by using the National Death Index. RESULTS: During an average follow-up of 12 years, 180 patients died. After adjustment for age, baseline cardiovascular disease, fasting plasma glucose level, high cholesterol level, overweight, current smoking, high blood pressure, and parental history of cardiovascular disease, men in the low-fitness group had an adjusted risk for all-cause mortality of 2.1 (95% CI, 1.5 to 2.9) compared with fit men. Men who reported being physically inactive had an adjusted risk for mortality that was 1.7-fold (CI, 1.2-fold to 2.3-fold) higher than that in men who reported being physically active. CONCLUSIONS: Low cardiorespiratory fitness and physical inactivity are independent predictors of all-cause mortality in men with type 2 diabetes. Physicians should encourage patients with type 2 diabetes to participate in regular physical activity and improve cardiorespiratory fitness.

Adult↗

Physical activity and self-reported, physician-diagnosed osteoarthritis: is physical activity a risk factor?

This prospective study evaluated regular physical activity and self-reported physician-diagnosed osteoarthritis of the knee and/or hip joints among 16,961 people, ages 20-87, examined at the Cooper Clinic between 1970 and 1995. Among those aged 50 years and older, osteoarthritis incidence was higher among women (7.0 per 1000 person-years) than among men (4.9 per 1000 person-years, P = 0.001), while among those under 50 years of age, osteoarthritis incidence was similar between men (2.6) and women (2.7). High levels of physical activity (running 20 or more miles per week) were associated with osteoarthritis among men under age 50 after controlling for body mass index, smoking, and use of alcohol or caffeine (hazard ratio = 2.4, 95% CI: 1.5, 3.9), while no relationship was suggested among women or older men. These findings support the conclusion that high levels of physical activity may be a risk factor for symptomatic osteoarthritis among men under age 50.

Adult↗

Exercise management of obesity.

When dealing with overweight patients, it is important to treat obesity as a chronic condition requiring long-term management. Physicians do not send a patient with hypertension home with just one bottle of pills and expect blood pressure to be managed forever. Similarly, it is naive to think that sending an overweight patient home with only a single word of advice to "lose weight" will solve the problem. Medical staff would be wise to adopt the attitude that obesity requires long-term intervention and management, just as hypertension requires ongoing monitoring and management. Continued attention to patients' physical activity is required. It is important for physicians to spend a few minutes discussing physical activity with their patients. The patient's current and past levels of physical activity should be assessed as well as the barriers to and benefits of activity. Normal-weight patients should accumulate at least 30 minutes of moderate-intensity activity on most days of the week, and overweight patients should accumulate 60 to 80 minutes per day, every day. The physician can provide some simple tools, such as a step counter and self-monitoring forms, to promote increases in activity and can follow up with the patient after the office visit. This information may sound like a lot to cover, especially given the limited time available for each patient. By spending 3 to 5 minutes intervening, however, physicians can play a critical role in promoting health. Physicians should set a goal to address one specific topic (e.g., a brief discussion of exercise benefits and barriers) and try one strategy (e.g., introduce self-monitoring) during the next counseling session with patients. It is also important for physicians to remember that their success in changing behavior may be in small increments. These small changes can and do eventually lead to success for many patients and physicians.

Adult↗

Heart rate variability, trait anxiety, and perceived stress among physically fit men and women.

BACKGROUND: It is unclear from prior reports whether the relationships between self-ratings of anxiety or emotional stress and parasympathetic nervous system components of heart rate variability are independent of personality and cardiorespiratory fitness. We examined those relationships in a clinical setting prior to a standardized exercise test. METHODS AND RESULTS: Heart rate variability (HRV) was measured during 5 min of supine rest among 92 healthy men (N=52) and women (N=40) who had above-average cardiorespiratory fitness as indicated by peak oxygen uptake measured during grade-incremented treadmill exercise. HRV datasets were decomposed into low-frequency (LF; 0.05-0.15 Hz) and high-frequency (HF; 0.15-0.5 Hz) components using spectral analysis. Self-ratings of trait anxiety and perceived emotional stress during the past week were also assessed. CONCLUSIONS: There was an inverse relationship between perceived emotional stress during the past week and the normalized HF component of HRV (P=0.038). This indicates a lower cardiac vagal component of HRV among men and women who perceived more stress. That relationship was independent of age, gender, trait anxiety, and cardiorespiratory fitness. It was also independent of heart rate; mean arterial blood pressure; and respiration rate, factors which can influence HRV and might be elevated among people reporting anxiety and perceived stress. We conclude that vagal modulation of heart period appears to be sensitive to the recent experience of persistent emotional stress, regardless of a person's level of physical fitness and disposition toward experiencing anxiety.

Adult↗

Cost-effectiveness of lifestyle and structured exercise interventions in sedentary adults: results of project ACTIVE.

BACKGROUND: Project ACTIVE was a randomized clinical trial comparing two physical activity interventions, lifestyle and traditional structured exercise. The two interventions were evaluated and compared in terms of cost effectiveness and ability to enhance physical activity among sedentary adults. DESIGN: This was a randomized clinical trial. SETTING/ PARTICIPANTS: The study included 235 sedentary but healthy community-dwelling adults. INTERVENTION: A center-based lifestyle intervention that consisted of behavioral skills training was compared to a structured exercise intervention that included supervised, center-based exercise. MAIN OUTCOME MEASURES: The main outcome measures of interest included cost, cardiorespiratory fitness, and physical activity. RESULTS: Both interventions were effective in increasing physical activity and fitness. At 6 months, the costs of the lifestyle and structured interventions were, respectively, $46.53 and $190.24 per participant per month. At 24 months these costs were $17.15 and $49.31 per participant per month. At both 6 months and 24 months, the lifestyle intervention was more cost-effective than the structured intervention for most outcomes measures. CONCLUSIONS: A behaviorally-based lifestyle intervention approach in which participants are taught behavioral skills to increase their physical activity by integrating moderate-intensity physical activity into their daily lives is more cost-effective than a structured exercise program in improving physical activity and cardiorespiratory health. This study represents one of the first attempts to compare the efficiency of intervention alternatives for improving physical activity among healthy, sedentary adults.

Adult↗

Comparison of a dietary record using reported portion size versus standard portion size for assessing nutrient intake.

OBJECTIVE: Because the percentage of missing portion sizes was large in the Aerobics Center Longitudinal Study (ACLS), careful consideration of the accuracy of standard portion sizes was necessary. The purpose of the present study was to investigate the consequences of using standard portion sizes instead of reported portion sizes on subjects' nutrient intake. METHODS: In 2307 men and 411 women, nutrient intake calculated from a 3-day dietary record using reported portion sizes was compared with nutrient intake calculated from the same record in which standard portion sizes were substituted for reported portion sizes. RESULTS: The standard portion sizes provided significantly lower estimates (>/= 20%) of energy and nutrient intakes than the reported portion sizes. Spearman correlation coefficients obtained by the two methods were high, ranging from 0.67 to 0.93. Furthermore, the agreement between both methods was fairly good. Thus, in the ACLS the use of standard portion sizes rather than reported portion sizes did not appear to be suitable to assess the absolute intake at the group level, but appeared to lead to a good ranking of individuals according to nutrient intake. These results were confirmed by the Continuing Survey of Food Intake by Individuals (CSFII), in which the assessment of the portion size was optimal. When the standard portion sizes were adjusted using the correction factor, the ability of the standard portion sizes to assess the absolute nutrient intake at the group level was considerably improved. CONCLUSIONS: This study suggests that the adjusted standard portion sizes may be able to replace missing portion sizes in the ACLS database.

Adult↗

Physical activity behavior change: issues in adoption and maintenance.

The many benefits of participation in regular moderate- or vigorous-intensity physical activity are well established, yet more than 60% of the population is sedentary or insufficiently active. Published studies have revealed that behavior modification and cognitive-behavior modification can be successfully used to assist patients, healthy adults, and youth in the adoption of physically active lifestyles. However, few studies with adults and youth have examined the maintenance of physical activity behavior beyond 6 months of adoption of this behavior. Maintenance of physical activity is critically important because ongoing participation in the behavior is necessary to sustain health benefits. Knowledge of effective intervention strategies for long-term maintenance of physical activity is at an early stage. The authors provide a summary of what is known about the maintenance of physical activity behavior in adults and youth and how physical activity behavior relates to other health behaviors such as smoking, as well as recommendations for research on physical activity behavior change and maintenance.

Adolescent↗

Muscular strength and physical function.

PURPOSE: The purpose of this study was to evaluate the potential association of muscular strength and endurance at baseline with the prevalence of functional limitations at follow-up. METHODS: Study participants were 3,069 men and 589 women (30-82 yr) who received a clinical examination including a strength evaluation at the Cooper Clinic between 1980 and 1989 and responded to a 1990 mail-back survey. Participants also had to achieve at least 85% of their age-predicted maximal heart rate on a maximal exercise treadmill test and have no history of heart attack, stroke, diabetes, high blood pressure, cancer, or arthritis at their first visit. A strength index composite score (0-6) was calculated using age- and sex-specific tertiles from bench press, leg press, and sit-up tests. Those scoring 5 or 6 were categorized in the high strength group. Functional health status was assessed by responses to questions about the participant's ability to perform light, moderate, and strenuous recreational, household, daily living, and personal care tasks. RESULTS: After an average follow-up of 5 yr, 7% of men and 12% of women reported at least one functional limitation. A logistic regression model including age, aerobic fitness, body mass index, and new health problems at follow-up found that, relative to those with lower levels of strength, the odds of reporting functional limitations at follow-up in men and women categorized as having higher levels of strength were 0.56 (95%CI = 0.34, 0.93) and 0.54 (95%CI = 0.21, 1.39), respectively. CONCLUSIONS: These findings, if replicated in other populations, suggest that maintenance of strength throughout the lifespan may reduce the prevalence of functional limitations.

Activities of Daily Living↗

The utility of the Digi-walker step counter to assess daily physical activity patterns.

PURPOSE: The Digi-Walker step counter is a promising and cost-effective tool to measure physical activity under free-living conditions. Two specific studies were conducted to evaluate the number of steps required to meet current physical activity guidelines. METHODS: Thirty-one adults (17 men, 14 women) served as participants. In study 1, we determined the number of steps to complete a mile under two different conditions and three paces. In study 2, we conducted a field trial to examine the relationship between daily step counts and other indices of physical activity. Participants in this study wore a Digi-Walker for 2 consecutive weeks and completed the 7-d physical activity recall (PAR) after each week. RESULTS: In study 1, there were no differences in step counts by site, but steps were inversely related to pace, with values ranging from 1330 to 1996. Individual step counts at a specific pace were negatively correlated with height, weight, leg length, and stride length and were positively correlated with body fatness. In study 2, participants had average daily step counts of 11,603 when structured vigorous activity was included and 8265 when only light and moderate activity were measured. Modest correlations were found between step counts and estimated energy expenditure. Similar correlations were observed when step counts were related to minutes of activity per day and minutes of sitting per day. CONCLUSIONS: Pedometers provide a useful indicator of daily step counts but variability in activity patterns make it difficult to establish step count guidelines that correspond with other public health guidelines.

Activities of Daily Living↗

A comparative evaluation of three accelerometry-based physical activity monitors.

PURPOSE: Accelerometry-based activity monitors offer promise for the assessment of free-living physical activity. They provide an objective record of frequency, intensity, and duration of physical activity with minimal burden on participants. The purpose of this study was to evaluate the absolute and relative validity of three contemporary activity monitors (Computer Science and Applications, Inc. [CSA], Tritrac, and Biotrainer) under both laboratory and field conditions. METHODS: Fifty-two participants completed two 30-min choreographed routines designed to simulate a variety of lifestyle physical activities. Three different treadmill paces were completed in both routines to evaluate reliability and validity under laboratory conditions. Six different lifestyle activities were also examined to evaluate the validity of the monitors under field conditions. During each routine, the activity levels of participants were monitored with the three activity monitors as well as by indirect calorimetry systems. RESULTS: The correlations between the monitors and measured VO2 were higher for treadmill activity (mean r = 0.86) compared with lifestyle activity (mean r = 0.55). Correlations among the different monitors were high for both treadmill (r = 0.86) and lifestyle activities (r = 0.70), suggesting that the monitors provide similar information under both conditions. Under laboratory conditions, the CSA yielded accurate predictions of energy expenditure (EE), whereas the Tritrac and Biotrainer tended to overestimate the EE (101-136% of measured value). The Tritrac, however, was found to have less error in individual estimates of EE. Under field conditions, all of the monitors underestimated EE (range: 42-67% of measured value). CONCLUSION: The observed differences among the monitors were attributed primarily to differences in the accuracy of the calibration equations rather than to the monitors themselves. Further research is needed to better understand how to use these devices for field-based assessments of physical activity.

Activities of Daily Living↗

Work ability, physical activity, and cardiorespiratory fitness: 2-year results from Project Active.

An adequate level of physical activity may maintain or promote work ability in aging workers. Project Active is a randomized trial comparing a Lifestyle physical activity program with a Structured exercise program in sedentary but healthy adults aged 35 to 60 years. Subjects in both groups received 6 months of intensive intervention followed by 18 months of active follow-up. The total number of subjects was 235, from which 80 subjects participated in the work ability assessment. Primary outcome measures were energy expenditure (kcal.kg-1.day-1), cardiorespiratory fitness (peak oxygen uptake in ml.min-1.kg-1), and the Work Ability Index. At 6 months, daily energy expenditure had increased significantly over baseline (mean +/- SD, from 33.0 +/- 0.9 to 34.4 +/- 1.8 kcal.kg-1.day-1) and was maintained over baseline at 24 months (34.0 +/- 2.5 kcal.kg-1.day-1). The significant increase in energy expenditure was observed particularly in moderate levels of activity. The average percentage of body fat was significantly higher at baseline compared with 6 months and 24 months. Peak oxygen uptake increased from baseline significantly during the first 6 months (from 29.6 +/- 5.7 to 30.6 +/- 6.3 ml.min-1.kg-1) and decreased to the baseline level (29.1 +/- 5.5 ml.min-1.kg-1) at 24 months. At baseline, the average Work Ability Index was 44.2 +/- 4.0, and it remained unchanged at 6 months (44.4 +/- 3.9) and at 24 months (44.2 +/- 3.1). In conclusion, a 2-year physical activity intervention increased daily energy expenditure, reduced body fat, and maintained peak oxygen uptake in healthy, middle-aged, sedentary subjects. The average Work Ability Index score at baseline was excellent and did not change during the 2-year physical activity interventions.

Adult↗

Does physical activity reduce the risk of developing peptic ulcers?

BACKGROUND: Although Helicobacter pylori has been identified as a major cause of chronic gastritis, not all infected patients develop ulcers, suggesting that other factors such as lifestyle may be critical to the development of ulcer disease. AIM: To investigate the role physical activity may play in the incidence of peptic ulcer disease. METHODS: The subjects were men (8529) and women (2884) who attended the Cooper Clinic in Dallas between 1970 and 1990. The presence of gastric or duodenal ulcer disease diagnosed by a doctor was determined from a mail survey in 1990. Subjects were classified into three physical activity groups according to information provided at the baseline clinic visit (before 1990): active, those who walked or ran 10 miles or more a week; moderately active, those who walked or ran less than 10 miles a week or did another regular activity; the referent group consisting of those who reported no regular physical activity. RESULTS: With the use of gender specific proportional hazards regression models that could be adjusted for age, smoking, alcohol use, body mass index, and self reported tension, active men were found to have a significant reduction in risk for duodenal ulcers (relative hazard (95% confidence interval) for the active group was 0.38 (0.15 to 0.94) and 0.54 (0.30 to 0.96) for the moderately active group). No association was found between physical activity and gastric ulcers for men or for either type of ulcer for women. CONCLUSIONS: Physical activity may provide a non-pharmacological method of reducing the incidence of duodenal ulcers among men.

Adult↗

Physical activity and peptic ulcers. Does physical activity reduce the risk of developing peptic ulcers?

BACKGROUND: Although Helicobacter pylori has been identified as a major cause of chronic gastritis, not all infected patients develop ulcers, suggesting that other factors such as lifestyle may be critical to the development of ulcer disease. OBJECTIVE: To investigate the role physical activity may play in the incidence of peptic ulcer disease. METHODS: The participants were men (n = 8,529) and women (n = 2,884) who attended the Cooper Institute for Aerobics Research, Dallas, Texas, between 1970 and 1990. The presence of gastric or duodenal ulcer disease diagnosed by a physician was determined from a mail survey in 1990. Participants were classified into 3 physical activity groups according to information provided at the baseline clinic visit (before 1990): active, those who walked or ran 10 miles or more a week; moderately active, those who walked or ran less than 10 miles a week or did another regular activity; and the referent group consisting of those who reported no regular physical activity. RESULTS: With the use of gender-specific proportional hazards regression models that could be adjusted for age, smoking, alcohol use, body mass index, and self-reported tension, active men had a significantly reduced risk for duodenal ulcers (relative hazard [95% confidence interval] for the active group, 0.38 [0.15-0.94], and 0.54 [0.30-0.96] for the moderately active group). No association was found between physical activity and gastric ulcers for men or for either type of ulcer for women. CONCLUSION: Physical activity may provide a nonpharmacologic method of reducing the incidence of duodenal ulcers among men.

Adult↗