Harold W. Kohl

Influences of cardiorespiratory fitness and other precursors on cardiovascular disease and all-cause mortality in men and women

OBJECTIVEnTo quantify the relation of cardiorespiratory fitness to cardiovascular disease (CVD) mortality and to all-cause mortality within strata of other personal characteristics that predispose to early mortality. DESIGN--Observational cohort study. We calculated CVD and all-cause death rates for low (least fit 20%), moderate (next 40%), and high (most fit 40%) fitness categories by strata of smoking habit, cholesterol level, blood pressure, and health status.nnnSETTINGnPreventive medicine clinic.nnnSTUDY PARTICIPANTSnParticipants were 25341 men and 7080 women who completed preventive medical examinations, including a maximal exercise test.nnnMAIN OUTCOME MEASURESnCardiovascular disease and all-cause mortality.nnnRESULTSnThere were 601 deaths during 211996 man-years of follow-up, and 89 deaths during 52982 woman-years of follow-up. Independent predictors of mortality among men, with adjusted relative risks (RRs) and 95% confidence intervals (CIs), were low fitness (RR, 1.52;95% CI, 1.28-1.82), smoking (RR, 1.65; 95% CI, 1.39-1.97), abnormal electrocardiogram (RR, 1.64;95% CI, 1.34-2.01), chronic illness (RR, 1.63;95% CI, 1.37-1.95), increased cholesterol level (RR, 1.34; 95% CI, 1.13-1.59), and elevated systolic blood pressure (RR, 1.34; 95% CI, 1.13-1.59). The only statistically significant independent predictors of mortality in women were low fitness (RR, 2.10; 95% Cl, 1.36-3.21) and smoking (RR, 1.99; 95% Cl, 1.25-3.17). Inverse gradients were seen for mortality across fitness categories within strata of other mortality predictors for both sexes. Fit persons with any combination of smoking, elevated blood pressure, or elevated cholesterol level had lower adjusted death rates than low-fit persons with none of these characteristics.nnnCONCLUSIONSnLow fitness is an important precursor of mortality. The protective effect of fitness held for smokers and nonsmokers, those with and without elevated cholesterol levels or elevated blood pressure, and unhealthy and healthy persons. Moderate fitness seems to protect against the influence of these other predictors on mortality. Physicians should encourage sedentary patients to become physically active and thereby reduce the risk of premature mortality.

What functional activities are important to patients with knee replacements

There is interest in quantifying the patient’s function and mobility after joint replacement. The current study identified activities important to patients having total knee replacement and the prevalence of limitations to participation in these activities. A Total Knee Function Questionnaire consisting of 55 questions addressing the patient’s participation in various activities was developed, validated, and mailed to 367 patients at least 1 year after knee replacement. Patients were asked the frequency with which they did each activity, the activity’s importance to them, and the extent to which their participation was limited by their knee replacement. The questionnaire was returned by 176 patients, 40% men and 60% women, with an average age of 70.5 years. The most prevalent activities were stretching exercises (73%), leg strengthening exercises (70%), kneeling (58%), and gardening (57%). The activities most important to the patients were stretching exercises (56%), kneeling (52%), and gardening (50%); those most difficult were squatting (75%), kneeling (72%), and gardening (54%). The current study showed a high correlation between the importance of activities and frequency of patient participation confirming that knee replacement successfully restores a significant degree of function. However, after knee replacement, improvements in knee function still are needed to allow patients to do all activities that they consider important.

Physical activity, physical fitness, and all-cause and cancer mortality: A prospective study of men and women

We studied physical fitness and physical activity in relation to all-cause and cancer mortality in a cohort of 7080 women and 25,341 men examined at the Cooper Clinic in Dallas, Texas, during 1970 to 1989. Physical fitness was assessed at baseline by a maximal treadmill exercise test, while physical activity was self-reported on the attendant health habits questionnaire. Both men and women averaged about 43 years of age at baseline (range, 20 to 88 years), and they were followed for approximately 8 years on average. Through the end of 1989, the women contributed 52,982 person-years of observation and incurred 89 deaths, including 44 deaths due to cancer. The men contributed 211,996 person-years and incurred 601 deaths, with 179 due to cancer. After adjustment for baseline differences in age, examination year, cigarette habit, chronic illnesses, and electrocardiogram abnormalities, we found a strong inverse association between risk of all-cause mortality and level of physical fitness in both men and women (P for trend < 0.001). Physically active men also were at lower risk of all-cause mortality than were sedentary ones (P for trend = 0.01). Among women, however, self-reported physical activity was not significantly related to risk of death from all causes. The risk of mortality from cancer declined sharply across increasing levels of fitness among men (P for trend < 0.001), whereas among women the gradient was suggestive but not significant (P for trend = 0.07). Physically active men also were at lower risk of death from cancer than were sedentary men (P for trend = 0.002), but among women physical activity was unrelated to cancer mortality.

Physical fitness, physical activity, and functional limitation in adults aged 40 and older

PURPOSEnA cohort of middle-aged and older men and women were followed for an average of 5.5 yr to examine the association between physical fitness, physical activity, and the prevalence of functional limitation.nnnMETHODSnThe participants received medical assessments between 1980 and 1988 and responded to a mail-back survey regarding functional status in 1990.nnnRESULTSnAmong 3495 men and 1175 women over 40 yr of age at baseline, 350 (7.5%) reported at least one functional limitation in daily or household activities at follow-up. The prevalence of functional limitation was higher among women than men. Physically fit and physically active participants reported less functional limitation than unfit or sedentary participants. After controlling for age and other risk factors, the prevalence of functional limitation was lower for both moderately fit (odds ratio = 0.4, 95% CI = 0.2-0.6) and high fit men (odds ratio = 0.3, 95% CI = 0.2-0.4), compared with low fit men. Corresponding figures for women were 0.5 (0.3-0.7) and 0.3 (0.2-0.5) for moderately fit and high fit women. The association between physical activity and functional limitation was similar to the data for physical fitness.nnnCONCLUSIONSnThese data support a protective effect of physical fitness and physical activity on functional limitation among older adults and extend this protective effect to middle-aged men and women.

Physical activity patterns associated with cardiorespiratory fitness and reduced mortality : The aerobics center longitudinal study

OBJECTIVESnThis study examined cross sectionally the physical activity patterns associated with low, moderate, and high levels of cardiorespiratory fitness.nnnMETHODSnPhysical activity was assessed by questionnaire in a clinic population of 13,444 men and 3972 women 20 to 87 years of age. Estimated energy expenditure (kcal.wk-1) and volume (min.wk-1) of reported activities were calculated among individuals at low, moderate, and high fitness levels (assessed by maximal exercise tests).nnnRESULTSnAverage leisure time energy expenditures of 525 to 1650 kcal.wk-1 for men and 420 to 1260 kcal.wk-1 for women were associated with moderate to high levels of fitness. These levels of energy expenditure can be achieved with a brisk walk of approximately 30 minutes on most days of the week. In fact, men in the moderate and high fitness categories walked between 130 and 138 min.wk-1, and women in these categories walked between 148 and 167 min.wk-1.nnnCONCLUSIONSnMost individuals should be able to achieve these physical activity goals and thus attain a cardiorespiratory fitness level sufficient to result in substantial health benefits.

Improvements in Cardiorespiratory Fitness Attenuate Age-related Weight Gain in Healthy Men and Women: The Aerobics Center Longitudinal Study

OBJECTIVE: To determine the longitudinal relation of change in cardiopulmonary fitness to subsequent change in body weight in a cohort of healthy middle-aged adults.DESIGN: Prospective cohort study.SUBJECTS: Participants were 4599 men and 724 women (43±9u2005y) receiving at least three medical examinations between 1970 and 1994. Examinations included assessment of cardiorespiratory fitness by maximal exercise tests and measurement of body weight.MEASUREMENTS: Change in fitness was calculated as the difference in maximal treadmill time between the first and second examination (mean interval, 1.8u2005y). Weight change was calculated as the difference in body weight between the first and last examination (mean follow-up, 7.5u2005y).RESULTS: There was a small, yet statistically significant weight gain over the follow-up (0.61±5.29u2005kg for men and 1.51±4.67u2005kg for women; P<0.001). Estimates from the multiple linear regression modeling show that each 1u2005min improvement in treadmill time, significantly attenuated weight gain in both men (b=−0.60; P<0.001) and women (b=−0.60; P<0.001), respectively. Moreover, each 1u2005min improvement in treadmill time, reduced the odds of a ≥5u2005kg gain by 14% in men (odds ratios (OR))=0.86; 95% confidence interval (CI): 0.83-0.89) and by 9% in women (OR=0.91; 95%CI:0.83-1.00) and the odds of a ≥10u2005kg gain by 21% in both men (OR=0.79;95% CI:0.75-0.84) and women (OR=0.79;95%CI:0.67-0.93)CONCLUSIONS: Improvements in fitness, appear important in attenuating age-related weight gain in healthy middle-aged adults. Thus, an active life-style should be promoted early and maintained through adulthood to prevent substantial weight gain and obesity with age.

Rates and Risks for Running and Exercise Injuries: Studies in Three Populations

Abstract We report on three epidemiologic studies of orthopedic injuries in exercisers. One group of 438 men and women ran approximately 25 mi per week; 24% reported an injury during the previous year. Higher weekly running mileage and heavier individuals were more likely to report an injury. Injuries were not associated with speed of running, age, gender, type of surface, time of day, or stretching habit. In a second study, rates of injury for the foot, knee, hip, back, shoulder, and elbow were examined in runner (n =2,102) and nonrunner (n =724) patients at a preventive medicine clinic. Only knee injury rates were significantly higher in runners. Third, participants (n=968) in worksite-sponsored exercise programs were evaluated for orthopedic injuries. Rates of exercise injuries were relatively low (net rate = 12%/year in exercisers). Risk of injury in participants starting a walking, running, or jogging program was associated (p <.05) with age, sex, body mass index, flexibility, cardiorespiratory endur...

Cyclic Pull-Out Strength of Hamstring Tendon Graft Fixation with Soft Tissue Interference Screws Influence of Screw Length

Blunt-threaded interference screws used for fixation of hamstring tendons in anterior cruciate ligament reconstructions provide aperture fixation and may provide a biomechanically more stable graft than a graft fixed further from the articular surface. It is unknown if soft tissue fixation strength using interference screws is affected by screw length. We compared the cyclic and time-zero pull-out forces of 7 25 mm and 7 40 mm blunt-threaded metal interference screws for hamstring graft tibial fixation in eight paired human cadaveric specimens. A four-stranded autologous hamstring tendon graft was secured by a blunt-threaded interference screw into a proximal tibial tunnel with a diameter corresponding to the graft width. Eight grafts were secured with a 25-mm length screw while the other eight paired grafts were secured with a 40-mm length screw. During cyclic testing, slippage of the graft occurred as the force of pull became greater with each cycle until the graft-screw complex ultimately failed. All grafts failed at the fixation site, with the tendon being pulled past the screw. There were no measurable differences in the mean cyclic failure strength, pull-out strength, or stiffness between the two sizes of screws. Although use of the longer screw would make removal technically easier should revision surgery be necessary, it did not provide stronger fixation strength than the shorter, standard screw as had been postulated.

A randomized trial of physical activity interventions: Design and baseline data from Project Active

We report here the design and baseline data from Project Active, a 2-yr randomized trial designed to compare the effectiveness of a Lifestyle physical activity intervention with the traditional Structured exercise prescription approach. Primary outcome measures are energy expenditure in physical activity (estimated by kcal per kilogram of body weight of energy expenditure) and cardiorespiratory fitness (measured by maximal oxygen uptake). The participants, 235 initially sedentary and apparently healthy adults, were randomized into either the Lifestyle or Structured intervention groups. The Lifestyle treatment consists of a personalized approach that accounts for an individuals motivational readiness and preferences for integrating physical activity into daily routines. The Structured approach is the familiar exercise prescription that is based on a frequency, intensity, and duration formula. The primary hypothesis to be tested is that there will be a difference in physical activity and cardiorespiratory fitness measures between the two conditions at the end of 24 months. The secondary hypothesis is that both groups will make significant improvements from baseline in physical activity and cardiorespiratory fitness at the end of 6 months. Six months of active intervention are followed by 18 months of a tapered follow-up maintenance intervention in both groups. Primary outcome measures are measured after 6 and 24 months.

Assessing physical activity among minority women: focus group results.

Focus group findings indicate a need to develop physical activity surveys that are more relevant for women, that include well-defined, inoffensive terminology, and that improve recall of unstructured and intermittent physical activities.