The risk of surgical site infection and re-admission in obese patients undergoing total joint replacement who lose weight before surgery and keep it off post-operatively.

This study evaluated whether obese patients who lost weight before their total joint replacement and kept it off post-operatively were at lower risk of surgical site infection (SSI) and re-admission compared with those who remained the same weight. We reviewed 444 patients who underwent a total hip replacement and 937 with a total knee replacement who lost weight pre-operatively and sustained their weight loss after surgery. After adjustments, patients who lost weight before a total hip replacement and kept it off post-operatively had a 3.77 (95% confidence interval (CI) 1.59 to 8.95) greater likelihood of deep SSIs and those who lost weight before a total knee replacement had a 1.63 (95% CI 1.16 to 2.28) greater likelihood of re-admission compared with the reference group. These findings raise questions about the safety of weight management before total replacement of the hip and knee joints.

How many days of pedometer monitoring predict weekly physical activity in adults?

BACKGROUND: The study purpose was to establish the number (and type) of days needed to estimate mean pedometer-determined steps/day in a field setting. METHODS: Seven days of data were collected from 90 participants (33 males, age = 49.1 +/- 16.2 years, BMI = 27.2 +/- 4.1 kg/m(2); 57 females, age = 44.8 +/- 16.9 years, BMI = 27.0 +/- 5.9 kg/m(2)). Mean steps/day were computed for all 7 days (the criterion), each single day, and combinations of days. Analyses included repeated measures ANOVA, intra-class correlations (ICC), and regression. RESULTS: There was a significant difference (P < 0.001) between days. The difference was limited to Sunday and accounted for 5% of the variance. ICC analyses indicated a minimum of 3 days is necessary to achieve a reliability of 0.80. The adjusted R(2) was 0.79 for a single day (specifically Wednesday), 0.89 for 2 days (Wednesday, Thursday), and 0.94 for 3 days (Wednesday, Thursday, Friday). Sunday was the last day to enter the model. CONCLUSIONS: Although there is a statistical difference between days, there is little practical difference, and the primary distinction appears limited to Sunday. Although a single day of collection is not acceptable, any 3 days can provide a sufficient estimate.

Effects of physical activity on exercise tests and respiratory function.

BACKGROUND: Exercise is an important component of pulmonary rehabilitation for patients with chronic lung disease. OBJECTIVE: To explore the role of physical activity in maintaining cardiac and respiratory function in healthy people. METHODS: Cardiorespiratory fitness was measured by a maximal treadmill test (MTT), and respiratory function was tested by spirometry. The cross sectional study included data from 24 536 healthy persons who were examined at the Cooper Clinic between 1971 and 1995; the longitudinal study included data from 5707 healthy persons who had an initial visit between 1971 and 1995 and a subsequent visit during the next five years. All participants were aged 25-55 years and completed a cardiorespiratory test and a medical questionnaire. RESULTS: In the cross sectional study, after controlling for covariates, being active and not being a recent smoker were associated with better cardiorespiratory fitness and respiratory function in both men and women. In the follow up study, persons who remained or became active had better MTT than persons who remained or became sedentary. Men who remained active had higher forced expiratory volume in one second (FEV(1)) and forced vital capacity (FVC) than the other groups. Smoking was related to lower cardiorespiratory fitness and respiratory function. CONCLUSIONS: Physical activity and non-smoking or smoking cessation is associated with maintenance of cardiorespiratory fitness. Change in physical activity habits is associated with change in cardiorespiratory fitness, but respiratory function contributed little to this association during a five year follow up.

The association between joint stress from physical activity and self-reported osteoarthritis: an analysis of the Cooper Clinic data.

OBJECTIVE: The purpose was to evaluate the association between estimated joint stress from physical activity (PA) and hip/knee osteoarthritis (OA). DESIGN: A nested case-control study was performed using data from the Aerobics Center Longitudinal Study. Participants without self-reported OA at baseline who attended the clinic between 1974 and 1993 and returned a follow-up questionnaire in 1990 or 1995 were eligible. Cases were those who reported a physician diagnosis of OA of the knee and/or hip at follow-up (N = 415). A random sample of persons in the remaining cohort were classified as controls (N = 1995). PA was measured at baseline by self-report and subjects were classified as 'moderate/high' or 'low' joint stress by PA type. Those reporting no PA were classified as sedentary with 'no' joint stress (the reference group). Men and women were analyzed separately. Stratified analysis and multiple logistic regression were used to assess the relationship between hip/knee OA and joint stress as predicted by PA. RESULTS: After adjustment for age, body mass index, years of follow-up, and history of hip/knee joint injury, among men, there was no association between hip/knee OA and low joint stress while moderate/high joint stress was associated with reduced risk of hip/knee OA (adjusted odds ratio (OR) = 0.62, 95% confidence interval (CI) = 0.43-0.89). Among women, both levels of joint stress were associated with reduced risk of hip/knee OA (OR = 0.58, 95% CI = 0.34-0.99 for low and OR=0.24, 95% CI = 0.11-0.52 for moderate/high). CONCLUSIONS: PA may reduce the risk of hip/knee OA, especially among women. Further research should assess the combined effects of frequency, intensity, duration and joint stress level of PA on incidence of hip/knee OA.

Limitations on the use of a single screening question to measure sedentary behavior.

OBJECTIVES: This study explored the limitations of identifying sedentary individuals via an existing screening question in a state-based surveillance system. METHODS: A national sample (n = 7529) of adults, selected by random-digit dialing between November 1999 and May 2000, responded about participation in leisure-time physical activity. RESULTS: Of those who initially reported no leisure-time physical activity (25%), 85% were engaging in at least some activity, and 20% were engaging in enough moderate- or vigorous-intensity activity to meet health-related recommendations. CONCLUSIONS: Public health programs that use only 1 screening question to identify sedentary behavior may not be able to target physical activity messages effectively, especially if physical activity is defined to include a broad range of activities beyond sports.

Association among physical activity level, cardiorespiratory fitness, and risk of musculoskeletal injury.

To help public health practitioners promote physical activities with a low risk of injury, this study determined the relation among type and duration of physical activity, cardiorespiratory fitness, and musculoskeletal injury in a sample of adults enrolled in the Aerobics Center Longitudinal Study. Subjects included 4,034 men and 967 women who underwent a baseline physical examination between 1970 and 1985 and who returned a mailed follow-up survey in 1986. At baseline, a treadmill graded exercise test was used to measure cardiorespiratory fitness. At follow-up, subjects reported injuries and type and duration of physical activity in the preceding 12 months. Polytomous logistic regression was used to estimate the association among physical activity type and duration, cardiorespiratory fitness, and injury. The risk of sustaining an activity-related injury increased with higher duration of physical activity per week and cardiorespiratory fitness levels. Results suggest that cardiorespiratory fitness may be a surrogate for unmeasured components of physical activity, such as exercise intensity. Among walkers, increasing duration of activity per week was not associated with an increased risk of injury. Results suggest that, for most adults, walking is a safe form of physical activity associated with a lower risk of injury than running or sport participation.

Population attributable risk: implications of physical activity dose.

PURPOSE: The purpose of this study is to describe the application of population attributable risk estimates in relation to the dose-related benefits or risks of physical activity. METHODS: Assumptions and limitations of population attributable risk calculations and interpretations are reviewed and evaluated in the context of physical activity dose. Theoretical estimates are developed for several hypothetical situations. RESULTS: National estimates of population attributable risk may be inaccurate because definitions and measurement techniques applied in physical activity research studies and physical activity prevalence surveys do not correspond. In addition, it is not established whether vigorous or moderate physical activity are independent contributors, sequential categories, or interactive variables in the process of disease reduction. This information is necessary to calculate population attributable risk most appropriately. CONCLUSION: Estimates of the disease burden of physical inactivity will be improved by two advances in empirical studies: first, the pairing of prevalence and relative risk estimates for nationally representative population-based samples; and second, refined relative risk estimates for various doses of physical activity.

Television watching, energy intake, and obesity in US children: results from the third National Health and Nutrition Examination Survey, 1988-1994.

OBJECTIVES: To examine the relationship between television watching, energy intake, physical activity, and obesity status in US boys and girls, aged 8 to 16 years. METHODS: We used a nationally representative cross-sectional survey with an in-person interview and a medical examination, which included measurements of height and weight, daily hours of television watching, weekly participation in physical activity, and a dietary interview. Between 1988 and 1994, the Third National Health and Nutrition Examination Survey collected data on 4069 children. Mexican Americans and non-Hispanic blacks were oversampled to produce reliable estimates for these groups. RESULTS: The prevalence of obesity is lowest among children watching 1 or fewer hours of television a day, and highest among those watching 4 or more hours of television a day. Girls engaged in less physical activity and consumed fewer joules per day than boys. A higher percentage of non-Hispanic white boys reported participating in physical activity 5 or more times per week than any other race/ethnic and sex group. Television watching was positively associated with obesity among girls, even after controlling for age, race/ethnicity, family income, weekly physical activity, and energy intake. CONCLUSIONS: As the prevalence of overweight increases, the need to reduce sedentary behaviors and to promote a more active lifestyle becomes essential. Clinicians and public health interventionists should encourage active lifestyles to balance the energy intake of children.

Be physically active each day. How can we know?

For the first time in its five versions, Nutrition and Your Health: Dietary Guidelines for Americans contains an apparently nondietary guideline recommending physical activity. Although new as a separate guideline, physical activity has been included in the weight guideline of previous versions. The current version recognizes the importance of physical activity to health beyond its effect on weight maintenance. The purpose of this paper is to examine what data are available or required to evaluate the level of physical activity in the population, particularly in light of current recommendations. The physical activity sections of several national surveys that assess individual behavior or activity-related policies are described. Surveillance of physical activity as a risk factor for chronic disease is critical because physical inactivity is highly prevalent, strongly associated with increased morbidity and mortality, costly and preventable. Determinants of physical activity behavior are also considered. These determinants are potentially important factors for surveillance and are critical components for planning successful interventions.

Physical activity-related injuries in walkers and runners in the aerobics center longitudinal study.

OBJECTIVE: To examine the association between physical activity-related injuries and participation in walking versus running. DESIGN: Nested case-control study. SETTING: Cooper Clinic Preventive Medicine Center, Dallas. Texas. PARTICIPANTS: 5,327 men and women undergoing exams between 1987 and 1995 and completing follow-up health history questionnaires in 1990 or 1995. Participants were classified as those reporting regular participation in walking or jogging/running at baseline. Those reporting both or neither activity were excluded from the study (n = 1404). Cases (698 men, 169 women) were those reporting physical activity-related injuries requiring physician visits in the previous year on the follow-up questionnaire. Controls (2,358 men, 698 women) were randomly selected from the remaining population. MAIN OUTCOME MEASURES: Logistic regression was used to examine the risk of injury in walkers versus runners and risk of injury by exercise dose while considering age, body mass index, previous injury, and strength training. RESULTS: There was a significantly lower risk of injury for walkers compared with runners in young (<45 years old) (odds ratio [OR] = 0.75, 95% confidence interval [CI] = 0.58-0.97) and older (> or = 45 years) men (OR = 0.64, 95% CI = 0.49-0.82), and a nonsignificantly lower risk among young (OR = 0.73, 95% CI = 0.39-1.37) and older women (OR = 0.72, 95% CI = 0.38-1.35). There was no effect of greater amounts of walking on injuries for either gender; however, there was a higher injury risk associated with running 15-30 min/day (OR = 1.36, 95% CI = 1.07-1.73) and 30+ min/day (OR = 1.52, 95% CI = 1.14-2.04) compared with <15 min/day among men, but not among women. CONCLUSIONS: This low risk of musculoskeletal injury suggests that participation in walking can be safely recommended as a way to improve health and fitness.

Comparison of three methods for measuring the time spent in physical activity.

PURPOSE: Three methods for measuring time spent in daily physical activity (PA) were compared during a 21-d period among 83 adults (38 men and 45 women). METHODS: Each day, participants wore a Computer Science and Applications, Inc. (CSA) monitor and completed a 1-page, 48-item PA log that reflected time spent in household, occupational, transportation, sport, conditioning, and leisure activities. Once a week, participants also completed a telephone survey to identify the number of minutes spent each week in nonoccupational walking and in moderate intensity and hard/very hard-intensity PA. Data were analyzed using descriptive statistics and Spearman rank-order correlations. Three equations developed to compute CSA cut points for moderate and hard/very hard PA were also compared with the PA logs and PA survey. RESULTS: There was modest to good agreement for the time spent in different PA intensity categories between the three CSA cut point methods (r = 0.43-0.94, P < 0.001). Correlations between the CSA and PA logs ranged from r = 0.22 to r = 0.36, depending on the comparisons. Correlations between the survey items and PA logs were r = 0.26-0.54 (P < 0.01) for moderate and walking activities and r < 0.09 (P > 0.05) for hard/very hard activities. Correlations between the survey items and the CSA min per day varied according to the method used to compute the CSA intensity cut points. CONCLUSIONS: The results were consistent with findings from other PA validation studies that show motion sensors, PA logs, and surveys reflect PA; however, these methods do not always provide similar estimates of the time spent in resting/light, moderate, or hard/very hard PA.

Public health surveillance of physical activity.

There is a clear public health need to measure and track physical activity behavior. Surveillance systems should be flexible enough to keep up with scientific advances in identifying dose-response relationships and in developing new assessment techniques, and new ways to assess community indicators associated with physical activity. Having a strong public health surveillance system that produces data that can be used to plan, guide, and evaluate programs is essential for increasing the prevalence of an important health-related behavior: physical activity.

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.

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.

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.

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.

Higher direct medical costs associated with physical inactivity.

The benefits of physical activity in reducing morbidity and mortality are well-established, but the effect of physical inactivity on direct medical costs is less clear.