Effects of voluntary wheel running on heart rate, body temperature, and locomotor activity in response to acute and repeated stressor exposures in rats

Stress often negatively impacts physical and mental health but it has been suggested that voluntary physical activity may benefit health by reducing some of the effects of stress. The present experiments tested whether voluntary exercise can reduce heart rate, core body temperature and locomotor activity responses to acute (novelty or loud noise) or repeated stress (loud noise). After 6 weeks of running-wheel access, rats exposed to a novel environment had reduced heart rate, core body temperature, and locomotor activity responses compared to rats housed under sedentary conditions. In contrast, none of these measures were different between exercised and sedentary rats following acute 30-min noise exposures, at either 85 or 98 dB. Following 10 weeks of running-wheel access, both groups displayed significant habituation of all these responses to 10 consecutive daily 30-min presentations of 98 dB noise stress. However, the extent of habituation of all three responses was significantly enhanced in exercised compared to sedentary animals on the last exposure to noise. These results suggest that in physically active animals, under some conditions, acute responses to stress exposure may be reduced, and response habituation to repeated stress may be enhanced, which ultimately may reduce the negative and cumulative impact of stress.     

Restraint, weight loss, and variability of body weight

Restrained and unrestrained subjects (n = 24) were weighed daily for a 6-week period and again 6 months later in order to determine whether dietary restraint or relative body weight is the better predictor of weight variability. Restraint was a significantly better predictor of naturally occurring weight fluctuations than was relative body weight. Furthermore, the 2 factors of the Restraint Scale, Concern for Dieting and Weight Fluctuations, were both significant predictors of weight variability. We propose that exaggerated weight fluctuations are not a natural concomitant of higher body weight but possibly the consequence of a cycle of dieting and overeating, which seems to preclude actual weight loss.     

Percentage body weight and the successive negative contrast effect in rats

In two runway experiments employing rats the successive negative contrast effect was evaluated for animals maintained at high or low body weights. In both experiments the effects on performance of shifting reward magnitude were independent of body weight. These results contrast with those of previous studies in which the successive negative contrast effect occurred only under low body weight. It was suggested that when conditions are maximal or near maximal for production of the successive negative contrast effect, as they were here but not in previous investigations, body weight will not influence the size of this effect.     

Stable vs unstable weight history, body-image, and weight concern in women of average body weight

The focus of this study was the effect of unstable weight history on current body-image among women. Participants were 45 college women of average weight (median age = 23 yr.); 15 had stable weight histories, 15 had past lowest weights 15% or more below current weight, and 15 had past highest weights 15% or more above current weight. The women were assessed on perceptual and attitudinal measures of body-image and a self-report measure of preoccupation with weight. In comparison to women with stable weight histories, those with unstable weight histories indicated greater dissatisfaction with the shape and size of their bodies, expressed more negative body attitudes, and reported increased concern about weight. Women with high weight histories overestimated their frontal body-size and expressed greater dissatisfaction with frontal size than women with low weight histories, but the two groups did not differ significantly on any of the other dependent measures. Possible explanations for increased body-image disturbance and weight concern among women with unstable weight histories are presented.     

Differences in body esteem by weight status,gender, and physical activity among young elementary school-aged children

Body satisfaction is important for the prevention of disordered eating and body image disturbances. Yet, little is known about body esteem and what influences it among younger children. The purpose of this study was to evaluate body esteem and the relationships between body esteem, weight, gender, and physical activity in elementary school children. A total of 214 third graders in a U.S. Midwestern state participated in this correlational study. The Body Mass Index-for-age, the Body Esteem Scale (BES), BE-Weight, BE-Appearance, and a Physical Activity Checklist were used to examine the relationships between the variables using bivariate correlations and analysis of variance. While children's body esteem did not differ by physical activity, important interactions were identified between weight status and gender in global body esteem and BE-Appearance. It is critical to examine attitudes about weight and appearance and the relationship between body esteem and self-esteem further among middle childhood-aged children.     

G.E. Moore and the relation between intrinsic value and human activity

The Journal of Value Inquiry -     

Ritanserin and voluntary alcohol intake in rats

In a previous study (Rammsayer & Vogel, 1991), rats selectively bred for high and low catecholamine responses to stress showed a selective response to the 5-HT2 receptor blocker ritanserin. However, it remained unclear whether selective breeding resulted in a decrease in 5-HT responsivity, as suggested by the lack of an effect in high stress responding rats, or in an increase in 5-HT responsivity, as suggested by ritanserin-induced reduction in alcohol intake in low-responding rats. To answer this question, nonselectively bred rats were forced to drink a 5% alcohol solution for 10 days. For the subsequent six days, animals were injected subcutaneously with 2.5 mg/kg/2 ml ritanserin or vehicle only, and both a 5% solution of alcohol and water were presented to the animals. Ritanserin neither affected alcohol nor total fluid intake suggesting that in the general population of N/NIH (Hansen) rats as well as in rats of the same strain selectively bred for high catecholamine responses, mesolimbic dopaminergic activity is not effectively modulated by specific blockade of 5-HT2 receptors. However, a very pronounced ritanserin induced difference in daily water intake between nonbred male and female rats became evident.     

Insulin and glucagon as determinants of body weight set point and microregulation in rats

Seven adult male rats were observed for body weight and microregulation (feeding, drinking, and running patterns) after manipulation of insulin and glucagon levels. They received three injections per day for 3 days each week of 3 U of protamine zinc insulin, .25 mg of zinc glucagon, 50 microgram of protamine zinc somatostatin (SRIF), or protamine zinc vehicle. Diabetes was then induced with an iv injection of streptozotocin (65 mg/kg), and the injection schedule was repeated after the full diabetic syndrome emerged. In all rats whose insulin levels were increased relative to glucagon levels, body weight increased; in those whose glucagon levels were increased relative to insulin levels, body weight decreased. All injections except vehicle reduced meal sizes in both normal and diabetic rats, but only insulin increased the frequency of feeding. These effects could be predicted by the glucostatic theory of food intake regulation and are thus interpreted as supportive of this theory. These results also support the hypothesis that the relative concentration of insulin to glucagon is a regulator of body weight set point.     

Accuracy of self-reported weight and role of gender,body mass index,weight satisfaction,weighing behavior,and physical activity among rural college students

This study measured accuracy of self-reported body mass index (BMI), particularly weight, in a college population. The main purpose was to examine the role of gender, BMI, body weight satisfaction, weighing frequency and physical activity level in accuracy (weight difference, percent weight difference, and absolute weight difference). Students (N = 405; 56% female) completed a questionnaire and 325 agreed to have their height and/or weight measured. Gender, BMI and activity level were significantly associated with weight difference and percent weight difference while BMI, activity level and weighing frequency were associated with absolute weight difference. However, interactions between BMI and physical activity were found. Our findings indicate that women and heavier individuals underestimate weight.     

Leftovers,body weight and sex of eater

The amount of food 66 males and 65 females (categorized as thin, average or overweight) left on their plates after eating was observed in a university cafeteria. The results indicated that the overweight did not leave significantly less. Routinely giving overweight patients the treatment directive of ‘leave food on your plates’ seems to be a questionable practice.     

Relationship between dietary restraint, energy intake, physical activity, and body weight: a prospective analysis.

Dietary, activity, and body weight differences in high- and low-restrained eaters and the independent impact of dietary restraint on body weight change were evaluated in 287 adults (141 men, 146 women) followed over a 1-year period. Analyses of measures of energy intake, physical activity, and dietary restraint indicated that high-restrained eaters did not differ in physical activity compared to low-restrained eaters at baseline but were ingesting significantly fewer kcal/lb and a higher percentage of the diet from fat. Body mass was significantly greater in both high-restrained men and high-restrained women than in their low-restrained counterparts. Regression modeling procedures revealed that weight and body mass at baseline were related to weight gain in men. In contrast, weight gain in women was predicted by baseline weight and higher restraint scores. These results indicate that dietary restraint is associated with weight gain in women but not in men.