Biomedical subjects

R K Dishman

Publications and source records attributed to R K Dishman.

At least 19 recordsLinked to original sources

PubMed2000

Treadmill exercise training augments brain norepinephrine response to familiar and novel stress.

In a test of hypothalamic-pituitary-adrenal (HPA) cortical and hypothalamic-pituitary-gonadal (HPG) interaction during familiar and novel stress, we previously reported that treadmill exercise training led to blunted plasma adrenocorticotrophin (ACTH) response to acute treadmill running but a hyper-responsiveness of ACTH after novel immobilization. In this follow-up analysis, we examined whether those results might be plausibly explained by a similar effect of treadmill exercise training on increased levels of norepinephrine (NE) in hypothalamic and limbic brain regions which synergize to modulate the release of ACTH during stress. Ovariectomized Sprague-Dawley rats that had been exercise trained by treadmill running or remained sedentary for 6 weeks received intramuscular injections of estradiol benzoate (Eb) or sesame oil on each of 3 days prior to 15 min of familiar treadmill running or novel immobilization. Treadmill exercise training, regardless of Eb treatment or type of stress, increased NE levels in the paraventricular (PVN), arcuate, medial preoptic, and ventromedial areas of the hypothalamus and protected against depletion of NE in the locus coeruleus, amygdala, and hippocampus. We conclude that treadmill exercise training has a hyperadrenergic effect in brain areas that modulate hypothalamic regulation of ACTH release during stress that is independent of HPA-HPG interaction and novelty of the stressor. To help elucidate these findings, the effects of treadmill exercise training on A1-A2 nuclei which innervate the PVN and their relationship with the limbic and hypothalamic responses we report require study.

Amygdala↗

PubMed2000

Factorial validity and invariance of questionnaires measuring social-cognitive determinants of physical activity among adolescent girls.

BACKGROUND: There are few theoretically derived questionnaires of physical activity determinants among youth, and the existing questionnaires have not been subjected to tests of factorial validity and invariance. The present study employed confirmatory factor analysis (CFA) to test the factorial validity and invariance of questionnaires designed to be unidimensional measures of attitudes, subjective norms, perceived behavioral control, and self-efficacy about physical activity. METHODS: Adolescent girls in eighth grade from two cohorts (N = 955 and 1,797) completed the questionnaires at baseline; participants from cohort 1 (N = 845) also completed the questionnaires in ninth grade (i.e., 1-year follow-up). Factorial validity and invariance were tested using CFA with full-information maximum likelihood estimation in AMOS 4.0. Initially, baseline data from cohort 1 were employed to test the fit and, when necessary, to modify the unidimensional models. The models were cross-validated using a multigroup analysis of factorial invariance on baseline data from cohorts 1 and 2. The models then were subjected to a longitudinal analysis of factorial invariance using baseline and follow-up data from cohort 1. RESULTS: The CFAs supported the fit of unidimensional models to the four questionnaires, and the models were cross-validated, as indicated by evidence of multigroup factorial invariance. The models also possessed evidence of longitudinal factorial invariance. CONCLUSIONS: Evidence was provided for the factorial validity and the invariance of the questionnaires designed to be unidimensional measures of attitudes, subjective norms, perceived behavioral control, and self-efficacy about physical activity among adolescent girls.

Adolescent↗

PubMed2000

The influence of acute exercise on sleep following high caffeine intake.

The purpose of this study was to examine the influence of vigorous acute exercise on nocturnal sleep that had been disrupted by high doses (1200 mg) of caffeine throughout the daytime. Eight moderately fit, young males with a history of moderate caffeine use completed four conditions in a within-subjects, counterbalanced design: 60 min of (i) cycling at 60% VO(2peak) or (ii) quiet rest following placebo consumption, (iii) cycling, or (iv) quiet rest following the consumption of a high dose of caffeine. Each condition was performed twice from 1615-1715 h and followed by all-night polysomnographic recording. Subjects consumed two blinded 200-mg capsules of either lactose placebo or caffeine upon awakening, at 1600 h, and 2 h before bedtime. State anxiety was assessed at bedtime. Criterion scores consisted of the mean data across the two days in each condition. Sleep data were analyzed using a condition (exercise versus quiet rest) by drug (caffeine versus placebo) repeated-measures ANOVA. Caffeine-elicited sleep disturbance that was less than previously reported. Exercise attenuated selected sleep disturbances to a small degree. In general, the effects of exercise on sleep were not greater following caffeine compared to placebo. Indeed, increases in slow-wave sleep after exercise were approximately 1/3 smaller following caffeine treatment compared to placebo.

Adult↗

PubMed2000

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↗

PubMed2000

Perceived submaximal force production in young adult males and females.

UNLABELLED: Clinical treatment in physical rehabilitation routinely uses perceived relative forces. PURPOSE: This study used psychophysical methods to quantify subjects' errors during submaximal muscular force production. METHODS: A sample of young adult (aged 23 +/- 3 yr) females (N = 60, 62 +/- 14 kg) and males (N = 50, 72 +/- 13 kg) performed a chest press on a hydraulic dynamometer with which they were unfamiliar. In four consecutive presses with a 2-min rest interval between each press, the subjects were asked to produce a force in the order of 25%, 50%, 75% of their maximal force, and a final maximal press. Pilot data (N = 10) indicated good reliability (r(xx) > 0.80) for the protocol. RESULTS: The rs between perceived force production and the desired production were 0.76 (P < 0.001) for males and 0.75 (P < 0.001) for females. The exponent for the power function between the perceived and desired forces was 1.12 for males and 1.03 for females. The total error ranged from 2.82 kg x m (males) to 1.22 kg x m (females). The rs and the logarithmic matching of perceived and desired force indicated a linear relationship that is consistent with Borg's range model, which has proposed that perceptual intensities of force for different people are approximately set equal at a subjective maximum. CONCLUSION: Many young healthy subjects can produce relative muscular forces with good accuracy. However, some subjects will provide very inaccurate forces that might affect outcomes in rehabilitation or physical training.

Adult↗

PubMed2000

Treadmill exercise training blunts suppression of splenic natural killer cell cytolysis after footshock.

This study extended to treadmill exercise training our prior report (Dishman RK, Warren JM, Youngstedt SD, Yoo H, Bunnell BN, Mougey EH, Meyerhoff JL, Jaso-Friedmann L, and Evans DL. J Appl Physiol 78: 1547-1554, 1995) that activity wheel running abolished the suppression of footshock-induced natural killer (NK) cell cytolysis. Twenty-four male Fischer 344 rats were assigned to one of three groups (n = 8, all groups): 1) a home-cage control group, 2) a sedentary treatment group, or 3) a treadmill-running group (0 degrees incline, 25 m/min, 35 min/day, 6 days/wk). After 6 wk, the treadmill and sedentary groups received 2 days of footshock. Splenic NK cytotoxicity was determined by standard 4-h (51)Cr release assay. Percentages of lymphocytes were determined by flow cytometry. Plasma levels of ACTH, corticosterone, and prolactin concentration were measured by radioimmunoassay. After footshock, percentage of lysis relative to home-cage controls was 40% and 80% for sedentary and treadmill-trained animals, respectively (P < 0.05). Our results indicate that the protective effect of chronic exercise on innate cellular immunity in the Fischer 344 male rat is not restricted to activity wheel running, nor is it explained by elevations in basal NK activity, increased percentages of splenic NK and cytotoxic T cells, or increased plasma levels of ACTH, corticosterone, and prolactin.

Adrenocorticotropic Hormone↗

PubMed1999

Brain noradrenergic responses to footshock after chronic activity-wheel running.

Effects of physical activity on brain noradrenergic response to footshock were examined. Male Fischer 344 rats were randomly assigned to shoebox cages with (AW) or without (SED) 24-hr access to an activity wheel for 4-5 weeks. Extracellular levels of norepinephrine (NE) and 3,4-dihydroxyphenyl-acetic acid (DOPAC) in the brain frontal cortex were measured in 20-min samples of microdialysate taken during a 2-hr baseline, 40 min of scrambled footshock, and a 1-hr recovery. Levels of messenger RNA (mRNA) for tyrosine hydroxylase (TH), c-fos, and prepro-galanin in the locus coeruleus were measured by in situ hybridization histochemistry with autoradiographic analysis. NE levels were the same for SED and AW rats at baseline but were elevated in SED compared with AW during and after footshock. Levels of mRNA for TH and c-fos were elevated after footshock but did not differ between SED and AW. Our findings suggest that wheel running blunts NE release in the brain frontal cortex in response to footshock but does not influence expression of the gene that encodes TH in the locus coeruleus.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1998

Activity wheel running blunts increased plasma adrenocorticotrophin (ACTH) after footshock and cage-switch stress.

We examined whether chronic circadian physical activity attenuates hypothalamic-pituitary-adrenal hormone responses after footshock with or without cage-switch stress. Young (45 g) male Fischer 344 rats were randomly assigned to individual suspended home cages (HC) or cages with activity wheels (AW) (12 h:12 h light-dark photoperiod). After 6 weeks, each animal from a pair matched on mass (HC and AW) and average weekly running distance (AW) was randomly assigned to controllable or uncontrollable footshock on 2 days separated by 24 h. Half the animals were returned to the HC after the first day of shock, and half were switched to a new shoebox cage. One animal of each pair could end the shock for both rats by performing an FR-2 lever press. The yoked animal could not control the shock. After shock on Day 2, trunk blood was collected after decapitation. Plasma adrenocorticotrophin (ACTH), corticosterone, and prolactin were determined by radioimmunoassay. ANOVA for a 2 Group (AW vs. sedentary) x 2 Test (controllable vs. uncontrollable shock) x 2 Condition (HC vs. cage-switch) design indicated a Group x Test x Condition effect [F(1, 48) = 5.07, p = 0.03] and a Test main effect [F(1, 47) = 6.93, p = 0.01] for ACTH. ACTH was higher for sedentary animals after uncontrollable footshock under cage-switch conditions and higher after uncontrollable versus controllable footshock when averaged across groups and cage conditions. No effects were found for corticosterone or prolactin. Our results extend to activity wheel running prior findings of a cross-stressor attenuation in plasma [ACTH] in response to cage-switch after treadmill exercise training, though the cross-stressor effect was additive with footshock. Consistent with our prior reports, the cross-stressor effect of wheel running was not apparent after footshock administered under home-cage conditions.

Adrenocorticotropic Hormone↗

PubMed1998

Worksite physical activity interventions.

BACKGROUND: National objectives for public health have targeted worksite as important settings for interventions to increase physical activity. However, expert reviews reveal no scientific consensus about the effectiveness of worksite interventions for increasing physical activity or fitness. METHODS: We judged the quantity and quality of existing evidence against scientific standards for the internal and external validity of the research design and the validity of measurements. Meta-analytic methods were used to quantify the size of effects expressed as Pearson correlation coefficients (r). Variation in effect was examined in relation to several features of the studies deemed important for implementing successful worksite interventions. Pre-experimental cohort studies were excluded because they are sensitive to secular trends in physical activity. RESULTS: Twenty-six studies involving nearly 9,000 subjects yielded 45 effects. The mean effect was heterogeneous and small, r = 0.11 (95% CI, -0.20 to 0.40), approximating 1/4 S.D., or an increase in binomial success rate from 50% to 56%. Although effects varied slightly according to some of the study features we examined, effects were heterogeneous within levels of these features. Hence, the moderating variables examined did not explain variation in the effects (P > 0.05). The exception was that effects were smaller in randomized studies compared with studies using quasi-experimental designs (P < 0.05). CONCLUSIONS: Our results indicate that the typical worksite intervention has yet to demonstrate a statistically significant increase in physical activity or fitness. The few studies that have used an exemplary sample, research design, and outcome measure have also yielded small or no effects. The generally poor scientific quality of the literature on this topic precludes the judgment that interventions at worksites cannot increase physical activity or fitness, but such an increase remains to be demonstrated by studies using valid research designs and measures.

Adolescent↗

PubMed1998

Acute exercise reduces caffeine-induced anxiogenesis.

PURPOSE: This experiment examined the influence of acute exercise on anxiety following caffeine-induced elevations in self-rated anxiety. METHODS: Eleven physically active, moderately fit males aged 25.1 +/- 3.8 yr completed four conditions in a within-subject, counterbalanced design involving 60 min of (1) cycling at 60% VO2peak or (2) quiet rest following placebo consumption (800 mg of lactose), as well as (3) cycling at 60% VO2peak and (4) quiet rest following 800 mg of caffeine. State anxiety and blood pressure were assessed 10 min before and 10 and 20 min after the conditions. RESULTS: A main effect for drug (caffeine vs placebo) determined by repeated measures ANOVA, (F(1,8) = 9.77; P = 0.01), indicated that state anxiety was elevated by caffeine. Drug effects were not obtained for blood pressure. Experimental hypotheses were tested by drug-by-condition (exercise vs quiet rest)-by-time (10 and 20 min postcondition) repeated measures ANOVA of change scores from the precondition baseline. A main effect for drug (F(1,8) = 5.81; P = 0.043) indicated that reductions in state anxiety were larger after caffeine ingestion. A condition-by-time effect (F(1,8) = 5.02; P = 0.055) indicated greater reductions in state anxiety 20 min after exercise compared with quiet rest. A condition effect for systolic blood pressure (F(1,10) = 4.56; P = 0.058) and condition-by-time interactions for diastolic (F(1,10) = 8.87; P = 0.014) and mean arterial blood pressures (F(1,10) = 8.46; P = 0.016) indicated reductions after exercise but not after quiet rest following both caffeine and placebo. CONCLUSIONS: We conclude that exercise can reduce anxiety elevated by a high dose of caffeine.

Adult↗

PubMed1997

Activity wheel running reduces escape latency and alters brain monoamine levels after footshock.

We examined the effects of chronic activity wheel running on brain monoamines and latency to escape foot shock after prior exposure to uncontrollable, inescapable foot shock. Individually housed young (approximately 50 day) female Sprague-Dawley rats were randomly assigned to standard cages (sedentary) or cages with activity wheels. After 9-12 weeks, animals were matched in pairs on body mass. Activity wheel animals were also matched on running distance. An animal from each matched pair was randomly assigned to controllable or uncontrollable inescapable foot shock followed the next day by a foot shock escape test in a shuttle box. Brain concentrations of norepinephrine (NE), dopamine (DA), dihydroxyphenylacetic acid (DOPAC), 5-hydroxytryptamine (5-HT), and 5-hydroxyindole acetic acid (5-HIAA) were assayed in the locus coeruleus (LC), dorsal raphe (DR), central amygdala (AC), hippocampus (CA1), arcuate nucleus, paraventricular nucleus (PVN), and midbrain central gray. After prior exposure to uncontrollable foot shock, escape latency was reduced by 34% for wheel runners compared with sedentary controls. The shortened escape latency for wheel runners was associated with 61% higher NE concentrations in LC and 44% higher NE concentrations in DR compared with sedentary controls. Sedentary controls, compared with wheel runners, had 31% higher 5-HIAA concentrations in CA1 and 30% higher 5-HIAA concentrations in AC after uncontrollable foot shock and had 28% higher 5-HT and 33% higher 5-HIAA concentrations in AC averaged across both foot shock conditions. There were no group differences in monoamines in the central gray or in plasma prolactin or ACTH concentrations, despite 52% higher DA concentrations in the arcuate nucleus after uncontrollable foot shock and 50% higher DOPAC/DA and 17% higher 5-HIAA/5-HT concentrations in the PVN averaged across both foot shock conditions for sedentary compared with activity wheel animals. The present results extend understanding of the escape-deficit by indicating an attenuating role for circadian physical activity. The altered monoamine levels suggest brain regions for more direct probes of neural activity after wheel running and foot shock.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1997

Increased finger arterial blood pressure after exercise detraining in women with parental hypertension: autonomic tasks.

The effects of exercise detraining on resting finger arterial blood pressure (BP), the carotid-cardiac vagal baroreflex, and BP and heart rate (HR) responses to mental arithmetic and forehead cold exposure were studied in young (19 +/- 1.1 years) normotensive women with parental history of hypertension. Following 8 weeks of aerobic exercise for 25 min, 3 days week-1 at an intensity of 60% VO2peak, subjects ceased training for 6-8 weeks. After detraining, VO2peak (mL kg-1 min-1) was reduced by 11.5% (41.1 +/- 6.9 to 36.4 +/- 4.8) coincident with an approximately equal to 10% increase in submaximal exercise heart rate. Responses to the laboratory tasks were then compared. Detraining was accompanied by increases (P < 0.05) in resting systolic (SBP) (113.6 +/- 8.9 to 121.2 +/- 9.0), diastolic (DBP) (63.0 +/- 8.4 to 68.3 +/- 6.8), and mean arterial (MAP) (78.7 +/- 8.4 to 84.2 +/- 7.3) BP (mmHg). None of the above changes occurred in sedentary matched-control subjects. Systolic blood pressure was elevated during forehead cold exposure and MAP was elevated during mental arithmetic after detraining, but the rates of response and recovery for SBP, DBP and MAP were not altered by detraining. Despite higher submaximal exercise HR after detraining, HR responses to autonomic challenges, including the carotid-cardiac vagal baroreflex, were unchanged between training and detraining. Our results indicate that exercise detraining increases resting finger arterial BP in young normotensive women at risk for hypertension with no effects on the rate of response or recovery of heart rate and BP during autonomic tasks known to elicit sympathetic and carotid-cardiac vagal activities in this population. The use of auscultatory brachial artery pressures in a similar study of women diagnosed with hypertension will clarify the clinical meaning of our findings.

Adolescent↗

PubMed1997

The effects of acute exercise on sleep: a quantitative synthesis.

We used meta-analytic methods to examine the influence of acute exercise on sleep. Thirty-eight studies were reviewed yielding 211 effects on 401 subjects. Mean effect sizes were calculated for sleep onset latency (SOL), stage 2, slow-wave sleep (SWS), rapid eye movement (REM) sleep, REM latency (REM-L), total sleep time (TST), and wakefulness after sleep onset (WASO). Moderating influences of subject fitness, heat load, exercise duration, time of day, associated light environment (i.e. indoor or outdoor), sleep schedule, and the scientific quality of the studies were examined. Effect sizes for SWS, REM, REM-L, and TST were moderate [0.18-0.52 standard deviation (SD)] and their associated 95% confidence intervals did not include zero. Exercise duration and time of day were the most consistent moderator variables. In contrast with previous hypotheses, heat load had little influence on sleep. The results of our quantitative synthesis of the literature are inconsistent with previous narrative reviews (1,2) which suggested that exercise elicits larger changes in sleep than those quantified in this meta-analysis. A major delimitation of published studies on the effects of acute exercise has been an exclusive focus on good sleepers. Hence, the effects we report herein may be underestimates of the efficacy of exercise for enhancing sleep among people with sleep disturbances.

Body Temperature↗

PubMed1997

Brain monoamines, exercise, and behavioral stress: animal models.

This paper summarizes our studies examining whether changes in levels of brain monoamines after chronic exercise are associated with altered behavioral and endocrine responses to stressors other than exercise. The focus is on using animal models relevant for understanding reports by humans that regular physical activity reduces depression and anxiety. We studied the effects of chronic activity wheel running or treadmill exercise training on levels of norepinephrine (NE) measured in brain cell bodies and terminal regions at rest and after behavioral stress. We also measured brain levels of serotonin, i.e., 5-hydroxytryptamine (5-HT), dopamine (DA), and gamma aminobutyric acid (GABA), which function as both antagonists and synergists with NE. In general, we found that chronic activity wheel running increased NE levels in the pons medulla at rest and protected against NE depletion in locus coeruleus cell bodies after footshock; the concomitant reduction in escape-latency was consistent with an antidepressant effect. Wheel running also decreased the density of GABAA receptors in the corpus striatum while increasing open-field locomotion, consistent with an anxiolytic effect, but had no effect on hypothalamic-pituitary-adrenal cortical response to footshock measured by plasma levels of adrenocorticotropic hormone (ACTH), corticosterone, and prolactin. In contrast, treadmill exercise training increased the metabolism of NE in brain ascending terminal areas for NE, increased the secretion of ACTH after footshock and immobilization stress and had no effect on GABAA receptor density or open field locomotion. The validity of animal models for studying depression and anxiety after forced versus voluntary exercise is discussed. Recommendations are offered for improving the methods used in this area of research.

Animals↗

PubMed1996

Increased open field locomotion and decreased striatal GABAA binding after activity wheel running.

Open-field behavior has been used to model reductions in anxiety-related behaviors in the rat after chronic physical activity. Plausible mechanisms for the increased open field locomotion observed after physical activity have not been studied. Open field locomotion is decreased by gamma-aminobutyric acid (GABA) and its agonists, and increased by GABA antagonists, in the ventral striatum. Hence, we tested the hypothesis that increased open field locomotion following chronic physical activity would be accompanied by a decrease in the number of GABAA receptors in the corpus striatum. Young (approximately 55 days) male Sprague-Dawley rats (N = 24) were randomly assigned to three conditions: 24-h access to an activity wheel (AW), running for 1 h without shock 6 days/week on a motorized treadmill (TM), or sedentary control (C). Open field locomotion (total and center squares traversed), defecation, and urination were assessed on each of 3 consecutive days prior to and again after 8 weeks of physical activity. Open field locomotion (total and center squares) increased after activity wheel running, decreased after treadmill training, and did not change for control animals. GABAA receptor density indicated by [3H] bicuculline binding (fmol/mg) was lower for activity wheel animals compared with treadmill animals and controls. GABA concentration (mumol/g) was not different between activity wheel and treadmill groups but was higher for both groups contrasted with controls. Our findings of decreased GABAA density in the corpus striatum concomitant with an increase in open field locomotion are consistent with an anxiolytic effect of chronic activity wheel running.

Animals↗

PubMed1996

Brain norepinephrine and metabolites after treadmill training and wheel running in rats.

Regional changes in concentrations of brain norepinephrine [NE] and its metabolites after chronic exercise have not been described for exercise protocols not confounded by other stressors. We examined levels of [NE], 3-methoxy-4-hydroxyphenylglycol [MHPG], and 3,4-dihydroxyphenylglycol [DHPG] in the frontal cortex, hippocampus, pons-medulla, and spinal cord after 8 wk of exercise. Male Sprague-Dawley rats (N = 36) were randomly assigned to three conditions: 1) 24-h access to activity wheel running (WR), 2) treadmill running (TR) at 0 degrees incline for 1 h.d-1 at 25-30 m.min-1, or 3) a sedentary control group (C). Levels (nmol.g-1) of [NE], [MHPG], and [DHPG] were assayed by high performance liquid chromatography with electrochemical detection. Planned contrasts (P < 0.05) indicated that exercise training increased succinate dehydrogenase activity (mmol cytochrome C reduced.min-1.g-1 wet weight) in soleus muscle for TR compared with WR or C. [NE] was higher in the pons-medulla and spinal cord for both TR and WR compared with C. [DHPG] was higher in the pons-medulla for TR compared with C, and [MHPG] was higher in the frontal cortex and in the hippocampus for TR compared with C. Our results suggest that treadmill exercise training is accompanied by brain noradrenergic adaptations consistent with increased metabolism of NE in areas containing NE cell bodies and ascending terminals, whereas treadmill running and wheel running are accompanied by increases in levels of NE in the areas of NE cell bodies and the spinal cord, independently of an exercise training effect.

Animals↗

PubMed1996

Physical activity, nutrition, and chronic disease.

Epidemiologic, animal, clinical, and metabolic studies demonstrate the independent roles of physical activity and nutrition in the prevention and treatment of several chronic diseases. Fewer data are available to describe the synergistic effects of exercise and diet, and questions remain as to whether and how these two lifestyle factors work together to promote health and prevent disease. This paper briefly reviews many of the known effects of physical activity and nutrition on the prevention and treatment of coronary heart disease, non-insulin-dependent diabetes mellitus, obesity, and osteoporosis as well as how exercise and diet may work together. A discussion of how to increase physical activity levels and how to improve dietary intake also is included. Finally, current exercise and dietary recommendations are summarized, as are directions for future research.

Animals↗

PubMed1996

Increasing physical activity: a quantitative synthesis.

National policy for increasing leisure physical activity in the United States is impeded by a poor understanding of interventions that can be implemented by community and clinical medicine. To clarify the literature in this area, we conducted a quantitative, meta analysis of 127 studies that examined the efficacy of interventions for increasing physical activity among approximately 131,000 subjects in community, worksite, school, home, and health care settings; 445 effects were expressed as a Pearson correlation coefficient (r) and examined as they varied according to moderating variables important for community and clinical intervention. The mean effect was moderately large, r = 0.34, approximating three-fourths of a standard deviation or an increase in binomial success rate from 50% to 67%. The estimated population effect weighted by sample size was larger, r = 0.75, approximating 2 standard deviations or increased success to 88%. Contrasts between levels of independent moderating variables indicated that effects weighted by sample size were larger when the interventions: 1) employed the principles of behavior modification, 2) used a mediated delivery, 3) targeted groups, 4) of combined ages, 5) sampled apparently healthy people, or 6) measured active leisure, of 7) low intensity, 8) by observation. Independently of sample size, effects were larger when interventions 1) used behavior modification, 2) employed a preor quasi-experimental design, or 3) were of short duration, regardless of features of the people, setting, or physical activity. Our results show that physical activity can be increased by intervention. The optimal ways for selecting intervention components, settings, and population segments to maintain increases in physical activity and the relative contributions by community and clinical medicine toward successful physical activity intervention require experimental confirmation, warranting accelerated attention in clinical trials.

Exercise↗