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Biomedical subjects

R R Pate

Publications and source records attributed to R R Pate.

At least 55 records · Page 3Linked to original sources
PubMed1995

Physical activity and health: dose-response issues.

The depth of our current knowledge of the dose-response gradient for physical activity and health is highly variable across the different health parameters. To the extent that the existing literature allows conclusions, it appears that (a) most health parameters are related to the amount of habitual physical activity in a graded fashion; (b) intensity of physical activity may be independently related, in a graded fashion, to some health parameters but unrelated to others; and (c) for some variables, the dose-response relationship is linear but, in other cases, is curvilinear. At present, these conclusions must be considered tentative, and most experts agree that further elucidation of dose-response relationships should be a major thrust of future research on physical activity and health.

Blood Pressure↗
PubMed1995

Relationship between physical activity level and cigarette, smokeless tobacco, and marijuana use among public high school adolescents.

This study analyzed the association between physical activity level and cigarette, smokeless tobacco, and marijuana use among a selected group of public high school students from South Carolina (N = 4,800). The 1993 CDC Youth Risk Behavior Survey was used to collect self-report information on physical activity, substance use, and other risk-taking behaviors. Multiple logistic regression analysis for weighted data (SUDAAN) was used for data analysis. Adjusted analysis showed significant associations (p < .05) among White males for use of cigarettes, smokeless tobacco, and marijuana, where higher levels of physical activity were inversely associated to use of these substances. Results from the study substantiate the importance of physical activity for adolescents, and demonstrate the need for future research to clarify the causal relationship between physical activity and substance use behaviors.

Adolescent↗
PubMed1994

Systolic blood pressure response to exercise in black and white preadolescent and early adolescent boys.

OBJECTIVE: To investigate differences in the response of systolic blood pressure (SBP) to exercise in black and white boys while controlling for the possible confounding effects of relative body weight, body surface area, physical work capacity index, preexercise SBP, and average power output. DESIGN: Comparative and correlational. PARTICIPANTS: Eighty-seven black and 52 white boys between the ages of 5 and 16 years. Participants were recruited from day camps, community centers, and summer recreation programs in and near Augusta, Ga. INTERVENTIONS: None. MEASUREMENTS/MAIN OUTCOMES: The slope of the SBP response to exercise was not significantly different between groups. Analysis of covariance revealed race, age, relative body weight, body surface area, preexercise SBP, and average power output to be significant univariate predictors of SBP at each power output. With multiple regression analyses, the effect of race was removed, and only preexercise SBP and average power output were found to be significant predictors of exercise SBP. CONCLUSION: There were no significant differences between black and white boys in the SBP response to exercise after controlling for the effects of preexercise SBP and average power output.

Adolescent↗
PubMed1994

Effects of exercise on macrophage activation for antitumor cytotoxicity.

Recent evidence suggests that exercise affects macrophage functions and that amount of exercise may be important. We determined effects of moderate (MOD) and exhaustive treadmill running (EXH) on 1) ability of macrophages to become activated for antitumor cytotoxicity after injection of heat-inactivated Propionibacterium acnes in vivo, 2) macrophage responsiveness to activating agents lipopolysaccharide and interferon-gamma, and 3) role of glucocorticoids and various macrophage metabolic products in modulating cytotoxicity in exercised animals. Male C3H/HeN mice were randomly assigned to MOD (18 m/min, 5% grade, 30 min/day) or EXH (18-35 m/min, 5%, 2-4 h) on a motor-driven treadmill. Control animals were kept in simulated treadmill lanes located directly over the runners. In general, both MOD and EXH increased cytotoxicity (42 and 22%, respectively, across all experiments; P < 0.05). Enhanced cytotoxicity was not due to altered macrophage adherence, tumor necrosis factor-alpha, interleukin-1 beta, or reactive oxygen species. Reactive nitrogen species were responsible for enhanced toxicity in EXH only. Macrophage cytotoxicity was further increased by lipopolysaccharide and interferon-gamma to a similar maximal level that was the same in all groups. Plasma corticosterone was elevated two- and fourfold in MOD and EXH, respectively, but there was no correlation between plasma corticosterone and macrophage cytotoxicity when compared across all groups even though cells were sensitive to steroid-mediated suppression in vitro. However, consistent with a corticosterone effect, EXH reduced the number of peritoneal macrophages elicited during P. acnes inflammation and abolished the typical exercise-induced increase in cytotoxicity of activated macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Effects of maximal exercise and venous occlusion on fibrinolytic activity in physically active and inactive men.

The purposes of this study were to 1) characterize changes in fibrinolytic activity in response to maximal exercise and 5-min venous occlusion and 2) compare responses in men of various habitual physical activity levels. Tissue plasminogen activator (TPA) activity and plasminogen activator inhibitor 1 (PAI-1) activity were measured in 15 inactive, 15 regularly active, and 15 highly active men. Data were analyzed using a three-way analysis of variance with repeated measures. Pretest TPA activity was similar among groups. TPA activity increased postexercise with higher values seen in the active groups (P < 0.001). The highly active group also significantly increased TPA activity postvenous occlusion (P < 0.01). Pretest PAI-1 activity was different among groups, with the inactive group showing the highest activity and the highly active group the lowest (P < 0.05). PAI-1 activity decreased with exercise (P < 0.01) but did not change with venous occlusion. In conclusion, active men exhibited greater changes in fibrinolytic activity with maximal exercise and venous occlusion than inactive men. This enhanced fibrinolytic activity may be an important mechanism mediating the cardioprotective effect provided by regular physical activity.

Adult↗
PubMed1994

Fibrinolytic responses to moderate intensity exercise. Comparison of physically active and inactive men.

The purposes of this study were to compare fibrinolytic responses to moderate intensity exercise in physically active and inactive men and during morning and evening exercise. Fourteen physically inactive men (mean age, 34.7 +/- 4.0 years) and 12 regularly active men (34.8 +/- 4.0 years) performed two exercise sessions, morning and evening, at 50% of maximal oxygen consumption. Tissue plasminogen activator (TPA) and plasminogen activator inhibitor-1 (PAI-1) activity were measured before and after exercise. Data were analyzed using a three-way ANOVA with repeated measures. TPA activity increased with exercise in both groups, although the active group demonstrated greater increases than the inactive group. Postexercise TPA activity was greater with evening than morning exercise. The inactive group exhibited greater PAI-1 activity than the active group. PAI-1 activity was higher during the morning than evening but did not change with exercise for either group. We conclude that moderate intensity exercise increases TPA activity in physically active and inactive men, with greater increases seen in active men, particularly during evening exercise. Moderate intensity exercise does not appear to affect PAI-1 activity. The lower PAI-1 activity in active men may be one mechanism whereby regular physical activity lowers the risk for coronary artery disease.

Adult↗
PubMed1994

Effects of exercise intensity, duration, and time of day on fibrinolytic activity in physically active men.

The purposes of this investigation were to determine: 1) whether the fibrinolytic responses to acute, submaximal exercise were best related to intensity, duration, or total caloric expenditure; and 2) whether the time of day exercise is performed affects the fibrinolytic response. Twelve physically active men (mean age = 34.8 +/- 4.0 yr) performed four 30-min exercise sessions: 50% VO2max, a.m. and p.m., and 80% VO2max, a.m. and p.m. Blood samples were analyzed for tissue plasminogen activator (TPA) activity and plasminogen activator inhibitor-1 (PAI-1) activity. Data were analyzed using a three-way ANOVA with repeated measures. TPA activity: preexercise TPA did not differ among the four sessions. TPA increased with exercise in all sessions except the 50% a.m. session. Exercise at 80% increased TPA more than 50% (P < 0.001) and evening sessions increased TPA more than morning sessions (P < 0.05). PAI-1 activity: preexercise PAI-1 activity was higher during the morning than evening and significantly decreased with exercise in all sessions except the 50% p.m. session. It was concluded that changes in fibrinolytic activity appear to be influenced primarily by exercise intensity rather than duration or total caloric expenditure. Additionally, time of day of exercise performance significantly influenced fibrinolytic activity.

Adult↗
PubMed1994

Effects of exercise on the immune response to cancer.

This study examined the effects of two doses of exercise on tumor incidence and progression, and the number and activity of intratumoral phagocytic cells (80% macrophages [M phi's]). Male mice were randomly assigned to control (CON), moderate (MOD) or exhaustive (EXH) treadmill running. Mice were inoculated subcutaneously with 2.5 x 10(5) mammary adenocarcinoma cells after 3 d of running (3 h after the last run at a point when enhancement in M phi cytotoxicity is observed). This tumor was chosen due to its susceptibility to M phi inhibition in vitro and in vivo. Mice continued daily running for 14 d. Food intakes were higher during the last 3 d in MOD and EXH, but body weights were no different. Flow cytometer analysis of tumor masses revealed that MOD had greater numbers of phagocytic cells (vs EXH) with slightly higher phagocytic activities (vs CON and EXH) (P < 0.05). However, no group differences in tumor appearance were seen except on day 7 when CON had less observable tumors than MOD and EXH (P < 0.05). Tumor size was also not different between groups at any point. These results indicate that moderate exercise can increase the phagocytic capacity of intratumoral phagocytic cells, but these changes had no apparent effect on tumor incidence or progression in this study.

Adenocarcinoma↗
PubMed1993

Validity of field tests of upper body muscular strength.

The purpose of this study was to determine the validity of five field tests (FTs) of upper body muscular strength and endurance (UBMSE) in 9-10-year-old children. Ninety-four children (38 boys, 56 girls) performed five FTs of UBMSE: pull-ups, flexed arm hang, push-ups, Vermont modified pull-ups (VMPU), and New York modified pull-ups. They also performed three criterion tests (CTs) of strength and three CTs of muscular endurance using a supported weight, set-resistance device. Zero-order correlations between the sum of the standard scores on the three CTs of strength (SUM1RM) and the FTs were nonsignificant. However, when SUM1RM was expressed relative to body weight (SUM1RM.kg-1), significant (p < .01) correlation coefficients were obtained for each FT. Highest correlations with SUM1RM.kg-1 were observed for the VMPU, and this same test yielded the smallest percentage of zero scores. Principal components analysis of the CTs, normalized for body weight, and FTs yielded a factor on which both the FTs and CTs of strength loaded significantly. These data indicate that the five FTs, though invalid as measures of absolute strength and muscular endurance, manifest concurrent and construct validity as measures of weight-relative muscular strength.

Arm↗
PubMed1993

Physical activity assessment in children and adolescents.

This article provides a review of the techniques that have been developed for measurement of physical activity in children and adolescents. Physical activity has been measured in youngsters using three major approaches: direct observation, heart rate or motion monitors, and self-report measures. Each of these techniques has relative benefits and deficiencies. Direct observation is a valid procedure requiring little interference and can provide good information concerning contextual variables (i.e., physical and social environment). However, direct observation is costly in terms of investigator and observer time. Motion sensors and heart rate monitors overcome problems associated with subject recall of activity and are less costly than direct observation. However, these instruments can be prone to technical problems and they provide no information concerning specific activities or the context in which activities are performed. Self-report and proxy report (e.g., by parents or teachers) techniques are relatively inexpensive, but their validity is limited by the ability of the subject (or proxy) to recall and report activity behavior. A major limitation in this field has been the lack of a "gold standard" measure of energy expenditure. The lack of such a criterion measure has precluded validation of the aforementioned activity measures as indicators of energy expenditure in children and youth.

Adolescent↗
PubMed1993

Iron status of female runners.

This study was designed to observe iron status and prevalence of iron deficient conditions in adult female habitual runners (n = 111) and inactive females of comparable age (n = 65). The runners were significantly lower (p < .05) than the reference group in mean serum ferritin (SF), total iron binding capacity, and red blood cell count, but significantly higher (p < .05) in mean corpuscular hemoglobin. The groups did not differ significantly in hemoglobin concentration, hematocrit, serum iron, percent saturation of transferrin, or red cell protoporphyrin. Chi square analysis indicated that iron depletion (SF < 20 ng.ml-1) was significantly more prevalent (p < .005) in the runners than in the controls. Anemia was extremely rare in both groups. A multiple regression analysis revealed significant negative associations between serum ferritin and coffee/tea intake (p < .001) and running activity (p < .05). These results indicate that habitual runners, as compared with inactive women, are at increased risk for iron deficient states but that full-blown anemia is a rare consequence of this deficient iron status.

Adult↗
PubMed1993

Exercise increases inflammatory macrophage antitumor cytotoxicity.

This study determined the effects of exercise on the ability of inflammatory macrophages to inhibit tumor cell growth in vitro (macrophage cytotoxicity). Thioglycollate injection (1 ml ip) was used as an inflammatory challenge and to partially activate macrophages for cytotoxicity. Inbred male C3H/HeN mice (n = 180) exercised moderately (MOD, 18 m/min, 30 min/day, 5% grade) or to exhaustion (EXH, 18-35 m/min, 2-4 h, 5% grade) on a motor-driven treadmill for 3 consecutive days after injection. Control (CON) mice were kept in stimulated treadmill lanes directly over the runners. Mice were killed immediately or 3 or 8 h postexercise. Macrophages from both MOD and EXH exercise groups manifested significantly (P < 0.05) enhanced (approximately 50%) cytotoxicity compared with those from CON group at all time points postexercise. This potentially beneficial exercise effect was not related to macrophage production of interleukin-1 beta, reactive nitrogen or oxygen intermediates, or number of macrophages in the assay but may have been manifested, in part, by tumor necrosis factor-alpha. Plasma corticosterone was significantly elevated immediately postexercise in MOD and EXH compared with CON mice; however, no evidence existed for an immuno-suppressive effect of corticosterone on macrophage cytotoxicity, perhaps because of insensitivity of inflammatory macrophages to glucocorticoid suppression seen in vitro. These data only partially support the "inverted U hypothesis," which states that moderate exercise may enhance, whereas very heavy exercise or a lack of exercise may attenuate, the immune response. Further study is needed to determine the physiological significance of these findings and the effects of exercise on macrophage subsets sensitive to glucocorticoid suppression (i.e., fully activated macrophages).

Animals↗
PubMed1993

Weekly variability in total body water using 2H2O dilution in college-age males.

The variability in measuring total body water (TBW) using deuterium oxide (2H2O) dilution has not been extensively tested. The purpose of this study was to determine the variability of weekly measurements of TBW utilizing the 2H2O dilution technique in 10 males and to determine the amount of biological versus technical variability using a generalizability ANOVA (GENOVA). Ten male subjects aged 21-32 yr were tested on four separate occasions for body weight (BW), underwater weight (UwWt), and TBW. BW remained quite stable across the four sessions with a 0.7% coefficient of variation (CV). Both UwWt and TBW had a CV of 4% across the four sessions. No differences were found between TBW estimates from plasma, saliva, or urine. GENOVA analysis determined that 25-50% of the total variability in measuring TBW was attributed to the sample analysis/separation procedures. Four percent of the TBW in these subjects was 1.8 l. This technique would therefore not be expected to detect changes less than 0.9 l (50% of 1.8 l). The estimates of %FAT from TBW were lower but not significantly different from UwWt. Blood, urine, and saliva were able to produce similarly repeatable measures of TBW.

Adult↗
PubMed1993

Self-selected exercise intensity of habitual walkers.

This study assessed self-selected exercise intensity of habitual walkers. Twenty-nine healthy adults (22 females, 7 males; age (mean +/- SD) = 34.9 +/- 8.6 yr) performed a typical exercise walk while walking speed was measured by an unseen observer. On a subsequent occasion, the subjects walked at the same pace on a treadmill while several variables related to exercise intensity were measured. The mean self-selected walking pace was 1.78 +/- 0.19 m.s-1. Mean percents of VO2max and HRmax elicited by the treadmill exercise were 52 +/- 11% and 70 +/- 9%, respectively. Mean MET level was 5.2 +/- 1.2, and ratings of perceived exertion (RPE) averaged 10.9 +/- 1.6. Based on reported frequency and duration of walking, weekly energy expenditure in exercise walking was estimated to be 1127 +/- 783 kcal.wk-1. These data suggest that the self-selected exercise intensity of healthy, habitual exercise walkers meets the American College Sports Medicine's recommendation for improvement of cardiorespiratory fitness. These data further suggest that, in this population, the average weekly energy expended through walking reaches a level associated with improvements in health and longevity.

Adult↗
PubMed1992

Physiologic and perceptual responses to exercise on a new cycle ergometer.

This study observed oxygen consumption (VO2), heart rate (HR), and rating of perceived exertion (RPE) during both maximal and submaximal exercise tests on a conventional Monark cycle ergometer and a new Velodyne ergometer. The Velodyne uses the subject's own bicycle attached to an electrically braked roller, which regulates power output. Trained male cyclists performed maximal exercise tests on both ergometers (N = 7) and two submaximal tests on each of three identical Velodynes and a Monark (N = 6). VO2, HR and RPE were measured during the submaximal and maximal tests. Data were analyzed via multiple repeated-measures ANOVA. No differences were found across cycles during the maximal or submaximal tests. The results indicate that the Monark and the Velodyne ergometers elicited similar physiologic and perceptual responses and that the Velodyne can be a viable alternative to the conventional Monark ergometer.

Adult↗