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At least 811 records · Page 45Linked to original sources

PubMed2005

Deep history impacts present-day ecology and biodiversity.

Lizards and snakes putatively arose between the early Jurassic and late Triassic; they diversified worldwide and now occupy many different ecological niches, making them ideal for testing theories on the origin of ecological traits. We propose and test the "deep history hypothesis," which claims that differences in ecological traits among species arose early in evolutionary history of major clades, and that present-day assemblages are structured largely because of ancient, preexisting differences. We combine phylogenetic data with ecological data collected over nearly 40 years to reconstruct the evolution of dietary shifts in squamate reptiles. Data on diets of 184 lizard species in 12 families from 4 continents reveal significant dietary shifts at 6 major divergence points, reducing variation by 79.8%. The most striking dietary divergence (27.6%) occurred in the late Triassic, when Iguania and Scleroglossa split. These two clades occupy different regions of dietary niche space. Acquisition of chemical prey discrimination, jaw prehension, and wide foraging provided scleroglossans access to sedentary and hidden prey that are unavailable to iguanians. This cladogenic event may have profoundly influenced subsequent evolutionary history and diversification. We suggest the hypothesis that ancient events in squamate cladogenesis, rather than present-day competition, caused dietary shifts in major clades such that some lizard clades gained access to new resources, which in turn led to much of the biodiversity observed today.

Adaptation, Biological↗

PubMed1991

Resting metabolic rate and energy balance in amenorrheic and eumenorrheic runners.

This study investigated metabolic and nutritional factors in association with athletic menstrual dysfunction (AMD). Three groups of women were studied: amenorrheic runners (amenorrheic), eumenorrheic runners (eumenorrheic), and eumenorrheic sedentary controls (sedentary). Amenorrheic and eumenorrheic were similar in age, weight, percent body fat by hydrodensitometry, training pace and mileage, best 10 km race time, years running, and maximal oxygen consumption. When adjusted for body weight or for fat-free mass by analysis of covariance, RMR was significantly lower in amenorrheic than in eumenorrheic and sedentary. The daily caloric intakes of the groups did not differ significantly, but the amenorrheic scored significantly higher than the eumenorrheic and sedentary on a scale of aberrant eating patterns. Amenorrheic high mileage runners seem to have a less adequate diet than eumenorrheic runners but appear to maintain energy balance and stable weight through a reduction in RMR.

Adaptation, Physiological↗

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↗

PubMed2000

Routes to obesity: phenotypes, food choices and activity.

Gain in body weight over a number of years could be achieved through cumulative positive energy balances. These positive balances could come about through adjustments in the various components of energy expenditure or fuel utilization, together with shifts in food selection or eating patterns leading to adjustments in macronutrient intake. This means that many combinations of intake and expenditure could lead to a positive energy balance; these combinations can be called routes to body weight gain. However, these routes are difficult to trace by studying random samples of individuals. Previous investigations have found a clear association between high fat consumption and the occurrence of obesity, and although a high fat intake is a strong behavioural risk factor for weight gain, the relationship does not constitute a biological inevitability. Some normal-weight and lean individuals appear to eat a high-fat diet. To investigate reasons for this we have studied individuals initially defined by particular clusters of dietary characteristics related to fat and carbohydrate consumption. Habitual high-fat (HF) and low-fat (LF) consumers have been termed phenotypes. Various aspects of energy expenditure (physiological and behavioural) and energy intake were measured in these individuals with contrasting profiles. HF phenotypes had high intakes of fatty foods and an overall higher energy intake than LF. However, these groups of young adult males had similar BMIs and percentage body fat. The HF had a significantly higher resting metabolic rate (RMR) and a lower RQ, together with high plasma fasting leptin levels, and a higher sleeping heart rate. In HF individuals the physical activity level was somewhat lower and they had significantly more periods of sedentary behaviour than LF subjects. Although HF individuals appear to be more vulnerable to developing obesity, both phenotypes carry particular risk factors and protective factors for weight gain. The use of phenotypes has allowed the identification of different potential routes to weight gain. Different strategies are required to prevent age-related increase in body weight in these quite different individuals.

Diet↗

PubMed2001

Dietary patterns and risk factors of diabetes mellitus among urban indigenous women in Fiji.

The dietary patterns of indigenous Fijians are changing rapidly. Dietary relationships in regard to the prevalence of diabetes are poorly studied in Fiji. A survey was conducted to show the relationship of dietary patterns and other lifestyle factors for the development of diabetes among urban indigenous women in Fiji. A sample of 200 Fijian women aged 30-39 who agreed to participate were interviewed by the use of semiquantitative food frequency, 3 day-24 h recall study. Physical activity and ceremonial dietary customs were also taken into consideration. Anthropometry included measurements of height, weight, waist and hip. Total percentage bodyfat measurements and glycosuria tests were also conducted. The results showed high rates of obesity manifested in high percentage bodyfat, high body mass index (BMI) and high waist and hip ratio (WHR). The mean 24 h dietary intake exhibited a moderate intake of protein, high intake of fat and a low intake of carbohydrate. The carbohydrate reduction was a result from the decline in consumption of traditional staples. Consumption of cereals and related products favored the high intake of butter and margarine and also encouraged the use of cooking oil in frying varieties of flour products. The daily intake of anti-oxidant vitamins of beta-carotene and vitamin E were low, however there was a high intake of vitamin C. The food frequency study revealed cassava, bread and sugar were consumed daily as the main carbohydrate foods. Fish and meat were the most frequently consumed protein foods. The main beverage was sweet tea with whole-cream milk. Butter, margarine, coconut cream, cheap lamb flaps and cooking oil provided the main sources of fat. Levels of physical activity included high sedentary lifestyles with a high rate of subjects being overweight and obese. Ceremonial dietary customs showed a high consumption of meat and fish. Fruits were rarely consumed. Glycosuria existed among the age group under study. The impact of dietary transition, coupled with dietary excesses and physical inactivity, seem to be potential risk factors of diabetes among the indigenous women in the urban area.

Adult↗

PubMed2006

Can self-reported preference for exercise intensity predict physiologically defined self-selected exercise intensity?

Exercise prescription guidelines emphasize the importance of individual preferences for different intensities, but such preferences have not been studied systematically. This study examined the hypothesis that the preference scale of the Preference for and Tolerance of the Intensity of Exercise Questionnaire would predict self-selected exercise intensity. Twenty-three previously sedentary middle-aged women participated in a treadmill test and a 20-min session at a self-selected intensity. After controlling for age, body mass index, and peak oxygen uptake, the preference scale accounted for significant portions of the variance in the percentage of oxygen uptake associated with the ventilatory threshold at Minute 15 and Minute 20 of the session at self-selected intensity.

Adult↗

PubMed2005

Effect of exercise training on plasma levels of C-reactive protein in healthy adults: the HERITAGE Family Study.

AIMS: To study the effect of exercise training on plasma C-reactive protein, a marker of inflammation. METHODS AND RESULTS: We performed a 20 week standardized exercise training programme in 652 sedentary healthy white and black men and women. C-reactive protein was measured with a high sensitivity assay. The study sample was stratified according to baseline C-reactive protein levels using a recommended classification (low <1.0 mg/L, n=265; moderate 1.0-3.0 mg/L, n=225; high >3.0 mg/L, n=162). The median C-reactive protein reduction was 1.34 mg/L in the high baseline C-reactive protein group. C-reactive protein levels did not change in the low or moderate baseline C-reactive protein groups. The difference among the C-reactive protein groups was significant adjusting for all correlates of baseline C-reactive protein (P<0.001) and additionally for changes in body weight, glucose, insulin, LDL cholesterol, HDL cholesterol, triglycerides, systolic and diastolic blood pressure, and maximal oxygen uptake (P<0.001). The C-reactive protein reduction in the high baseline C-reactive protein group was consistent across all population groups (P<0.001 for difference among baseline C-reactive protein groups). CONCLUSION: Plasma C-reactive protein levels are reduced in response to exercise training in sedentary healthy adults with high initial C-reactive protein levels. This finding may partly explain the effectiveness of regular physical activity in the prevention and treatment of cardiovascular and metabolic diseases.

Adult↗

PubMed1998

Prevalence and correlates of recreational physical activity in women aged 50-64 years.

OBJECTIVE: To evaluate the prevalence of recreational physical activity in middle-aged women and to identify characteristics predisposing women to an active or sedentary lifestyle. DESIGN: In this population-based survey study of 492 women aged 50-64 years, women were interviewed between 1988 and 1993 regarding their recreational exercise habits, other health habits, and medical history. Women were selected from the general population of western Washington State through random-digit-dialing of telephones. Physical activities in a recent 2-year period were recorded, including specific types, frequency, and duration of each activity. RESULTS: Fewer than half of the women reported doing any regular physical activity and only 27% engaged in any high intensity exercise. Obesity, current cigarette smoking, low income, low education, and some dietary factors were associated with a sedentary lifestyle. CONCLUSIONS: These results suggest that only about half of middle-aged women engage in any regular recreational exercise, and that less than 25% follow the National Institutes of Health recommended guidelines for light to moderate exercise for at least 30 min per day, 6 days per week.

Age Factors↗

PubMed1977

Sexually dimorphic effects of forced exercise on food intake and body weight in the rat.

The food intake (FI), body weight (BWt) and water intake (WI) of adult male and female rats were compared during a seven day period of forced exercise in a treadmill. Work loads for the exercised groups were gradually increased across the seven-day test period, whereas work loads for the sedentary controls were maintained at the same level used during a previous three-day training period. Relative to their respective control groups, male rats showed a decrease in FI and BWt in response to the exercise challenge, but female rats showed an increase in FI sufficient to maintain their BWt at control levels. Both male and female rats showed a reliable increase in WI during the period of forced exercise. These sexually dimorphic changes in FI and BWt in response to forced exercise indicate that female rats are capable of demonstrating a more vigorous defense of BWt than are male rats and suggest that there is a sex difference in the long-term control of feeding behavior in the rat.

Animals↗

PubMed2005

Profile of overweight and obese people in a Mediterranean region.

OBJECTIVE: To assess the prevalence of excess weight (obesity and overweight) and the related environmental risk factors in a Mediterranean population. Self-perception of body weight, attitudes toward weight-control behaviors, and the associated factors were also examined. RESEARCH METHODS AND PROCEDURES: A cross-sectional nutritional survey was carried out in the Balearic Islands between 1999 and 2000. A random sample (n = 1200) of the adult population (20 to 60 years old) was interviewed. Dietary questionnaires and a global questionnaire incorporating questions related to sociodemographic and lifestyle variables were utilized. Anthropometric measurements were also obtained. RESULTS: Nearly one-half of the population of the Balearic Islands is above the normal weight range (BMI > 25). The predictors of overweight and obesity in the Balearic Islands are to be over 40 years old, to be married, to form part of the lowest educational levels, and to have a sedentary lifestyle. A large percentage of excess-weight individuals tend to underestimate their BMI, are not concerned about their weight status, tend to snack more often, and have never dieted. DISCUSSION: Although the likely causes of the rise in obesity prevalence are difficult to elucidate from this study, we have identified the profile of individuals with excess weight in the Balearic Islands as well as their attitudes toward their body image.

Adult↗

PubMed1997

Physical activity and lipoprotein metabolism: epidemiological evidence and clinical trials.

Prospective epidemiological studies have proven a close link between the lipoprotein profile and cardiovascular morbidity and mortality. As physical activity is accepted as a significant factor improving physical fitness and lipoprotein metabolism, there is evidence that physically active men have a lower cardiovascular risk due to their higher metabolic fitness. Physical activity and physical fitness are generally linked to higher HDL cholesterol and lower LDL cholesterol as well as lower triglyceride and insulin levels. However, in cross-sectional studies the differences in lipoprotein cholesterol evaluated by routine measures in healthy physically active individuals and sedentary controls are only minor compared to therapeutical aims. The impact of exercise and training is often more significant when the effect of exercise on lipoprotein subfractions and apolipoprotein levels are taken into account. Dramatic differences can be documented in concentrations of cardioprotective HDL subset2 and atherogenic small, dense LDL subset6 levels in relation to the individual status of aerobic fitness and body composition in adults. These observations indicate that the preventive and therapeutical use of physical activity is of particular significance in a population of cardiovascular risk or patients with reduced daily activity. Our own experience in clinical trials shows that even in short-term programs (4 weeks to 6 months) changes in activity and eating behavior may lead to important improvements of the metabolic risk and lipid profile. Understanding the complex interaction between exercise and metabolic control of the lipid profile as well as the correlation with other risk parameters will improve the knowledge of prescribing exercise programs in patients at risk.

Adult↗

PubMed1990

Hyperactivity aggravates semistarvation-induced changes in corticosterone and triiodothyronine concentrations in plasma but not luteinizing hormone and testosterone levels.

Semistarvation over a ten-day period resulted in a weight loss of 30% in male Wistar rats, which had continuous access to a running wheel. The animals increased their activity up to 20 km per day. Controls fed ad lib increased activity only slightly (up to 2.3 km on day ten). Groups of semistarved and ad lib-fed sedentary rats were studied as controls. The circadian pattern of corticosterone (B), triiodothyronine (T3), luteinizing hormone (LH) and testosterone (T) was studied. Corticosterone was synergistically increased by semistarvation and exercise. The reduction of triiodothyronine by semistarvation was significantly greater in the running wheel group. Both luteinizing hormone and testosterone were significantly decreased by semistarvation. Hyperactivity did not result in additional suppression of LH and testosterone.

Animals↗

PubMed1995

Prescribing exercise in multiple short bouts versus one continuous bout: effects on adherence, cardiorespiratory fitness, and weight loss in overweight women.

OBJECTIVE: To investigate whether prescribing exercise in several short-bouts versus one long-bout per day would enhance exercise adherence, cardiorespiratory fitness, and weight loss in overweight adult females in a behavioral weight control program. DESIGN: Randomized controlled trial with subjects randomized to either a short-bout exercise group (SB, n = 28, age = 40.4 +/- 5.9 yrs) or a long-bout exercise group (LB, n = 28, age = 40.9 +/- 7.3 yrs), with subjects followed for a period of 20 weeks. Both groups were instructed to exercise 5 days per week with exercise duration progressing from 20 to 40 min per day. The LB group performed one exercise bout per day, whereas the SB group performed multiple 10 min bouts of exercise per day. The recommended caloric intake for all subjects was 5022-6277 kJ/day (1200-1500 kcal/day), with fat reduced to 20% of caloric intake. SUBJECTS: Fifty-six obese, sedentary females (BMI = 33.9 +/- 4.1 kg/m2). MEASUREMENTS: Exercise participation was assessed from self-reported diaries and Tri-Trac Accelerometers. Cardiorespiratory fitness was assessed using a submaximal cycle ergometer test. RESULTS: Exercising in multiple short-bouts per day improved adherence to exercise: the SB group reported exercising on a greater number of days (mean +/- s.d. = 87.3 +/- 29.5 days vs 69.1 +/- 28.9 days; P < 0.05) and for a greater total duration (223.8 +/- 69.5 min/week vs 188.2 +/- 58.4 min/week; P = 0.08) than the LB group. Predicted VO2Peak increased by 5.6% and 5.0% for the LB and SB groups, respectively (P < 0.05). There was a trend for the weight loss to be greater in the SB group (-8.9 +/- 5.3 kg) compared to the LB group (-6.4 +/- 4.5 kg; P < 0.07). CONCLUSION: These results suggest that short-bouts of exercise may enhance exercise adherence. Short-bouts of exercise may also enhance weight loss and produce similar changes in cardiorespiratory fitness when compared to long-bouts of exercise. Thus, short-bouts of exercise may be preferred when prescribing exercise to obese adults.

Adult↗

PubMed2002

Stages of change among ethnically diverse college students.

The authors applied the stage-of-change construct in the transtheoretical model to examine the distribution of Asian (n = 869), African American (n = 373), White (n = 1322), and Hispanic (n = 535) American undergraduate students across the 5 stages of change for exercise. Stage of change varied as a function of ethnicity. Higher percentages of minorities were in the precontemplation and contemplation stages. The likelihood of being in these stages was from 43% to 82% greater for minorities than for White students. Also examined were the congruency between stage of change and self-reported levels of physical activity. Half of the sedentary students and 15.6% of the active students were misclassified by the stage-of-change procedure. Misclassification rates were higher for minority women (27.8%) than for White women (17.8%) and for Asian students (24.6%) compared with all others (20.6%). The results of this study have implications for the design of physical activity interventions based on stage of change.

Adolescent↗

PubMed2005

A classification model of grazing areas in southern Italy using Remote Sensing data.

Detection of vegetation typologies is of particular interest in epidemiological studies on animal diseases. This paper is focused on the automatic detection of grazing areas in southern Italy browsed by equines, oxen and sheep, mostly sedentary, with many in fenced areas for overnight stays. Results revealed Satellite Remote Sensing was an indispensable tool in area surveys for vegetation cover characterization. Our classification model shows an accuracy level of 90.21% and a precision of 92.69%. Results suggest similar application protocols can be used in areas with different vegetation cover to characterizing potential infection risk areas for geohelminths and other diseases.

Agriculture↗

PubMed2006

Monoamine oxidase A activity and norepinephrine level in hippocampus determine hyperwheel running in SPORTS rats.

An understanding of neurological mechanisms for wheel running by rodents, especially with high exercise activity, would be applicable to a strategy for promotion of exercise motivation in humans. One of several brain regions that are candidates for the regulation of physical exercise is the hippocampus. Here we examined the running activity of Spontaneously-Running-Tokushima-Shikoku (SPORTS) rat, a new animal model for high levels of wheel-running activity, and its relation with the hippocampal norepinephrine (NE) system including the levels of NE, adrenergic receptors, and degradation enzymes for monoamines. In the hippocampus of SPORTS rats, the level of NE in extracellular fluid was augmented, whereas the level in the homogenate of the whole tissue was decreased even for sedentary conditions. Elevated extracellular NE caused downregulation of alpha(2)-adrenergic receptors in the hippocampus of SPORTS rats. Local administration of alpha(2)-adrenergic receptor antagonist yohimbine, but not of alpha(2)-agonist clonidine, into the hippocampus suppressed high running activity in SPORTS rats. The protein expression and the activity levels of monoamine oxidase A (MAOA), a critical enzyme for the degradation of NE, were decreased in the hippocampus of SPORTS rats to increase extracellular NE level. Thus, inhibition of oxidase activity in normal Wistar rats markedly increased wheel-running activity. These results indicate that decreased MAOA activity, elevation of extracellular NE, and alpha(2)-adrenergic receptors in the hippocampus determine the neural basis of the psychological regulation of exercise behavior in SPORTS rats.

Adrenergic alpha-2 Receptor Agonists↗

PubMed1998

Activity-controlled circadian base rate.

The current pacing rates are clustered around a fixed base rate since pacemaker patients are usually sedentary, resting, or sleeping most of the time. This fixed base rate is either too low for daytime hemodynamic support or too high for nighttime rest and recovery. Multiple Holter studies involving normal individuals have suggested that the resting base rate fluctuates during the course of the day. The circadian base rate (CBR) algorithm was designed to provide patients with a circadian change in paced resting rate and a normal rate distribution. The CBR algorithm, using a sophisticated accelerometer sensor, was developed and tested using the downloaded activity data from patients implanted with Trilogy DR+ pacemakers. Twenty-five patients (19 men, 6 women, age 72 +/- 9 years) were studied. Trilogy DR+ is able to record the detailed sensor and system behavior data for a week. During outpatient visits, the pacemaker was interrogated and the data accumulated in the pacemaker memory were downloaded. The CBR algorithm was applied to the activity variance histogram to calculate the base rate and to construct its histogram. The base rates in the CBR histogram are generally below 100 ppm with a distribution that mimics the natural sinus rate distribution of normal subjects. The CBR algorithm provides the highest daytime rates for hemodynamic support and the lowest nighttime rates for cardiac recovery, with a smoothly changing base rate modeling the normal circadian variation in heart rate.

Aged↗

PubMed2002

Neighborhood and physical activity outcomes in women: regional comparisons.

The environment a person lives in can play a large role in determining whether they exercise. This study examined the physical activity level of women living in either a northern or a southern region of the United States. Sedentary women were recruited to be part of a program designed to increase walking. Women were measured on the time it took to walk 1 mile, lung capacity, BMI, percent body fat, and mood. We found significant regional differences at baseline and change on outcomes over time. Awareness of the relationship between community/neighborhood and physical activity can be useful for designing fitness programs that are sensitive to environmental differences in women's lives.

Adult↗