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PubMed2004

Hippocampal BDNF mediates the efficacy of exercise on synaptic plasticity and cognition.

We found that a short exercise period enhanced cognitive function on the Morris water maze (MWM), such that exercised animals were significantly better than sedentary controls at learning and recalling the location of the platform. The finding that exercise increased brain-derived neurotrophic factor (BDNF), a molecule important for synaptic plasticity and learning and memory, impelled us to examine whether a BDNF-mediated mechanism subserves the capacity of exercise to improve hippocampal-dependent learning. A specific immunoadhesin chimera (TrkB-IgG), that mimics the BDNF receptor, TrkB, to selectively bind BDNF molecules, was used to block BDNF in the hippocampus during a 1-week voluntary exercise period. After this, a 2-trial-per-day MWM was performed for 5 consecutive days, succeeded by a probe trial 2 days later. By inhibiting BDNF action we blocked the benefit of exercise on cognitive function, such that the learning and recall abilities of exercising animals receiving the BDNF blocker were reduced to sedentary control levels. Inhibiting BDNF action also blocked the effect of exercise on downstream systems regulated by BDNF and important for synaptic plasticity, cAMP response-element-binding protein (CREB) and synapsin I. Specific to exercise, we found an association between CREB and BDNF expression and cognitive function, such that animals who were the fastest learners and had the best recall showed the highest expression of BDNF and associated CREB mRNA levels. These findings suggest a functional role for CREB under the control of BDNF in mediating the exercise-induced enhancement in learning and memory. Our results indicate that synapsin I might also contribute to this BDNF-mediated mechanism.

Activating Transcription Factor 1↗

PubMed2004

Aerobic exercise training and cardiovascular reactivity to psychological stress in sedentary young normotensive men and women.

Forty-five (22 women) sedentary young (18-30 years old) nonsmoking normotensive volunteers engaged in either 6 weeks of aerobic training (AT), weight training (WT), or a no-treatment (NT) condition to determine whether AT lowers systolic (SBP) and diastolic (DBP) blood pressure, heart rate (HR), and rate-pressure product (RPP) during rest, psychological stress, and recovery periods. Estimated VO(2)max increased for the AT (32.1+/-1.1 to 38.4+/-1.0 ml.kg(-1).min(-1)). A smaller increase for the WT (30.5+/-1.1 to 33.8+/-1.0) was likely due to increased leg strength, and VO(2)max did not change for the NT (32.5+/-1.1 to 32.9+/-1.0). Heart rate and RPP levels were lower during psychological stress and recovery after training for AT relative to the WT and NT. Overall SBP was also lower in the AT relative to the NT but not the WT. In conclusion, aerobic training lowered cardiovascular activity levels during psychological stress and recovery in healthy young adults, implying a protective role against age-related increases in coronary heart disease for individuals who adopt aerobic exercise early in life and maintain the behavior across the life span.

Adult↗

PubMed2002

Physical activity, health impairments, and disability in neuromuscular disease.

Reduced physical activity is a consequence of progressive neuromuscular diseases, which negatively impacts quality of life and health outcomes. Reduced functional muscle mass is common to all neuromuscular diseases and results from both atrophy of disuse secondary to a sedentary lifestyle and muscle degeneration secondary to the disease itself. This review summarizes current concepts relating to the impact of reduced physical activity on health and fitness, potential determinants of physical activity levels in neuromuscular diseases, and new approaches to the quantitative measurement of physical activity in neuromuscular disease populations. The interrelationship of disease pathophysiology, impairment, functional limitation, disability, and societal limitation in the determination of physical activity in the community in neuromuscular diseases is discussed using Duchenne muscular dystrophy as an example. Future research pertaining to physical activity in neuromuscular disease will need to focus on the development of scientifically based recommendations concerning optimal exercise approaches with both disease-specific and general guidelines.

Persons with Disabilities↗

PubMed1986

Medial hypothalamic lesions in Syrian hamsters: characterization of hyperphagia and weight gain.

Syrian golden hamsters (Mesocricetus auratus) received bilateral lesions aimed at the ventromedial hypothalamus (VMH) or a sham lesion. In the first study, some of the animals in each surgical group were housed in standard sedentary conditions while others had free access to running wheels. The lesions produced a 30% increase in the daily intake of chow, and this was accomplished exclusively by increased meal sizes. As a result, lesioned hamsters gained body weight relative to controls both on the chow diet and in a subsequent high fat diet phase. The effects were comparable in both sedentary and exercising groups. The lesions produced increases in body length and fat content. In the second study, lesions were made in the VMH or in adjacent nuclei and, after an initial period on chow, the hamsters were then given a choice between chow and high fat diet. The lesioned hamsters showed no unusual preference for the high fat diet but, as before, those with damage to the VMH or paraventricular nucleus (PVN) showed exaggerated body weight gain. Hamsters with these lesions were hyperinsulinemic in both fed and fasted conditions at the end of the study.

Animals↗

PubMedDate not supplied

Can a health unit take action on the determinants of health?

There is growing interest in improving population health by multi-sectorial partnerships that address the determinants of health. The Leeds, Grenville and Lanark District Health Unit worked with some 80 other community agencies to form the Lanark, Leeds and Grenville Health Forum in the spring of 2000. The goals of this Health Forum were to evaluate the determinants of health of the population over a five-year period, identify activities within an overall Health Improvement Plan to address these determinants, pursue ongoing resources for interventions, assess their impact on health, and modify plans and activities accordingly. The Health Forum identified that their region had increased mortality rates from cardiovascular disease and cancers compared with the rest of Ontario. The local district health unit offered three possible determinants to explain this: socio-economic determinants (residents below provincial average for income and education), behavioural determinants (residents had higher rates of smoking, sedentary activity and high fat diets) and lack of access to health care. The Health Forum developed a Health Improvement Plan to work on each of these determinants. Throughout its lifetime, the Health Forum proved to be both active and productive, leading to many cooperative ventures. This paper provides a brief overview of the approach taken with its Health Improvement Plan, as well as the successes and limitations of this approach. The experience of the Leeds, Grenville and Lanark Health Forum offers a practical model for public health units to work with partner agencies to address the determinants of health, as well as some insights into the requirements to sustain such a model.

Cardiovascular Diseases↗

PubMed2001

Randomised controlled trial of primary school based intervention to reduce risk factors for obesity.

OBJECTIVE: To assess if a school based intervention was effective in reducing risk factors for obesity. DESIGN: Group randomised controlled trial. SETTING: 10 primary schools in Leeds. PARTICIPANTS: 634 children aged 7-11 years. INTERVENTION: Teacher training, modification of school meals, and the development of school action plans targeting the curriculum, physical education, tuck shops, and playground activities. MAIN OUTCOME MEASURES: Body mass index, diet, physical activity, and psychological state. RESULTS: Vegetable consumption by 24 hour recall was higher in children in the intervention group than the control group (weighted mean difference 0.3 portions/day, 95% confidence interval 0.2 to 0.4), representing a difference equivalent to 50% of baseline consumption. Fruit consumption was lower in obese children in the intervention group (-1.0, -1.8 to -0.2) than those in the control group. The three day diary showed higher consumption of high sugar foods (0.8, 0.1 to 1.6)) among overweight children in the intervention group than the control group. Sedentary behaviour was higher in overweight children in the intervention group (0.3, 0.0 to 0.7). Global self worth was higher in obese children in the intervention group (0.3, 0.3 to 0.6). There was no difference in body mass index, other psychological measures, or dieting behaviour between the groups. Focus groups indicated higher levels of self reported behaviour change, understanding, and knowledge among children who had received the intervention. CONCLUSION: Although it was successful in producing changes at school level, the programme had little effect on children's behaviour other than a modest increase in consumption of vegetables.

Body Mass Index↗

PubMed1988

Sports medicine and the wheelchair athlete.

International competitions for the wheelchair-confined are now a major feature of the world of sport. They are helpful in improving both mood state and physiological function, while improving long term prognosis. Immediate medical problems are much as in other types of competition, but there are also specific problems (bladder infections, pressure sores, intolerance of environmental extremes, and injuries related to wheelchair use). Disability classification, based on the anatomical or functional level of a lesion, provides a reasonably fair basis for competition. Most of the functional data to date relate to strength (isometric and isokinetic) and aerobic power (measured in a wheelchair or on an arm ergometer). While the inactive patient is often severely limited, wheelchair athletes may have a greater functional capacity than sedentary normals. The principles of training for the wheelchair-confined are much as in the able-bodied, although because the arm muscles are small, much of the training response may be peripheral rather than central. The margin between an effective stimulus and overtraining is also reduced. Involvement in a training programme not only increases physiological function, but also counters depression, increasing the subject's sense of self-efficacy. Biomechanicians are now contributing increasingly to wheelchair sport, improving the design of competitive wheelchairs, improving the mechanical efficiency of participants, and helping to reduce the risks of injury. The benefits of wheelchair sport are now clearly established, and family physicians should do more to encourage the involvement of the wheelchair-confined.

Competitive Behavior↗

PubMed2006

Characteristics of frail older adult drivers.

OBJECTIVES: To determine the prevalence of driving in older adults with mild to moderate physical frailty and to compare characteristics of current frail older adult drivers with those of former drivers in the sample. DESIGN: Retrospective study of frail older adults enrolled in randomized trials of exercise and hormone replacement therapy. SETTING: Urban, academic medical center. PARTICIPANTS: One hundred eighty-three sedentary community-dwelling men and women aged 75 and older with mild to moderate physical frailty, as defined by two of the following three criteria: modified Physical Performance Test (PPT) score between 18 and 32, peak oxygen uptake (VO2) between 10 and 18 mL/kg per minute, and self-report of difficulty or assistance with one activity of daily living (ADL) or two instrumental ADLs. Participants were classified as current or former drivers. MEASUREMENTS: Demographic characteristics, medical diagnoses, medication use, modified PPT score, and psychometric tests. RESULTS: The majority (85%) of the participants were drivers. Former drivers were more likely to be older, be female, reside in congregate independent living for the elderly, have a higher incidence of arthritis and congestive heart failure, take sedating medications, have lower total ADL scores, have lower VO2 peak scores, and have more impairment on tests of cognition and physical strength, although only age, type of residence, and grip strength were independent predictors of driving cessation in the regression analysis. CONCLUSION: Despite the presence of physical frailty, many older adults choose to continue to drive. Further studies are needed to better understand the driving behaviors of frail older adults and explore opportunities for optimizing driving abilities.

Activities of Daily Living↗

PubMed2006

Non-exercise activity thermogenesis: the crouching tiger hidden dragon of societal weight gain.

Non-exercise activity thermogenesis (NEAT) is the energy expenditure of all physical activities other than volitional sporting-like exercise. NEAT includes all the activities that render us vibrant, unique, and independent beings such as working, playing, and dancing. Because people of the same weight have markedly variable activity levels, it is not surprising that NEAT varies substantially between people by up to 2000 kcal per day. Evidence suggests that low NEAT may occur in obesity but in a very specific fashion. Obese individuals appear to exhibit an innate tendency to be seated for 2.5 hours per day more than sedentary lean counterparts. If obese individuals were to adopt the lean "NEAT-o-type," they could potentially expend an additional 350 kcal per day. Obesity was rare a century ago and the human genotype has not changed over that time. Thus, the obesity epidemic may reflect the emergence of a chair-enticing environment to which those with an innate tendency to sit, did so, and became obese. To reverse obesity, we need to develop individual strategies to promote standing and ambulating time by 2.5 hours per day and also re-engineer our work, school, and home environments to render active living the option of choice.

Animals↗

PubMed1995

Childhood obesity: pathophysiology and treatment.

Childhood obesity is among the most difficult problems which pediatricians treat. It is frequently ignored by the pediatrician or viewed as a form of social deviancy, and blame for treatment failure placed on the patients or their families. The definition of obesity is difficult. Using total body electrical conductivity (TOBEC) technology, total body fat ranges between 12% and 30% of total body weight in normal children and adolescents. This is influenced not only by age, but also by physical fitness. Anthropometry is the easiest way to define obesity. Children whose weight exceeds 120% of that expected for their height are considered overweight. Skinfold thickness and body mass index are indices of obesity that are more difficult to apply to the child. Childhood obesity is associated with obese parents, a higher socioeconomic status, increased parental education, small family size and a sedentary lifestyle. Genetics also clearly plays a role. Studies have demonstrated that obese and non-obese individuals have similar energy intakes implying that obesity results from very small imbalances of energy intake and expenditure. An excess intake of only 418 kJ per day can result in about 4.5 kg of excess weight gain per year. Small differences in basal metabolic rate or the thermic effects of food may also account for the difference in energy balance between the obese and non-obese. In the Prader Willi Syndrome, there appears to be a link between appetite and body fatness. When placed on growth hormone, lean body mass increases, body fat decreases, sometimes to normal, and appetite becomes more normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1998

Physical activity interventions in low-income, ethnic minority, and populations with disability.

BACKGROUND: Low-income, racial and ethnic minority, and populations with disabilities are more likely to be sedentary than the general population. Increasing physical activity in these groups is an important public health challenge. This report summarizes interventions that have targeted populations at risk for inactivity. METHODS: Computer and manual searches were performed to identify manuscripts published from 1983 to 1997. Interventions conducted in these populations in which physical activity was part of the intervention, and activity or cardiorespiratory fitness were outcome measures, were included in the review. RESULTS: Fourteen studies were identified. Most studies used pre-post or quasi-experimental designs. Common intervention features for the ten studies that included ethnic minority groups were community advisory panels, community needs assessments, and community members delivering the intervention. Eight studies reported a theoretical framework that guided the intervention. Increased physical activity was documented in two studies. Post-intervention follow-up was conducted in two studies; both reported no significant findings. Only four studies for people with disabilities were found; all four reported post-intervention physical activity change. CONCLUSION: Much work remains to develop effective interventions for these populations. Research that involves the community at all steps in the design and implementation of the intervention shows greatest promise for promoting behavior change. Future intervention studies should include: (1) rigorous experimental designs; (2) theoretically based interventions; and (3) validated assessment instruments to detect physical activity change.

Adolescent↗

PubMed2006

A health assessment tool for multiple risk factors for obesity: results from a pilot study with UK adults.

OBJECTIVE: Although many individual health behaviours have been implicated in the current rise in obesity levels, their confounding or cumulative effects have yet to be established. This study piloted a measure of multiple risk factors for obesity, designed to assess their relative importance at individual and population levels. METHODS: A 100-item, user-friendly, self-report questionnaire, was completed by 80 adult volunteers (67% female, age range 19-73 years), and related to Body Mass Index (BMI). RESULTS: Dietary factors significantly related to BMI were higher amount of food consumption and more non-hunger related eating. BMI was strongly related to both negative attitudes/emotions towards and negative social influences on physical activity/exercise. Higher BMI was also related to less participation in physical activity/exercise, more sedentary leisure pursuits (e.g. TV watching) and lower general activity levels (e.g. more car usage). A regression analysis of all risk factors explained around 56% of the variance in BMI. CONCLUSION: The pilot measure was able to differentiate between weight groups on a number of risk factors. The strong associations found between BMI and attitudes, emotions and social influences on eating and activity behaviours may help explain why many diet and exercise regimes are unsuccessful. PRACTICE IMPLICATIONS: Results demonstrate that an easy-to-complete, self-report tool of multiple risk factors for obesity has potential as a health assessment tool for use by health professionals.

Adult↗

PubMed2004

Changes in health-related behaviours and cardiovascular risk factors in young adults: associations with living with a partner.

OBJECTIVE: To examine changes in cardiovascular risk factors and health-related behaviours in young Australian adults at a stage of transition from the family environment. STUDY DESIGN: Repeated surveys between 9 and 25 years of age in a community-based group that included 569 eighteen-year-olds and 600 twenty-five-year-olds. RESULTS: There were significant increases (P < 0.001 for all variables) in body mass index (BMI) [men 2.5 kg/m2 (2.0); women 1.7 kg/m2 (2.9)], waist girth [men 7.6 cm (6.5); women 4.3 cm (7.2)], BP (systolic/diastolic) [men 5(12)/7(8) mm Hg; women 3(10)/6(7) mm Hg] and in total cholesterol [men 15% increase; women 9%]. The proportion of sedentary behaviour increased from 19% to 39% in men (P < 0.001) and from 40% to 41% (P = 0.801) in women. Cohabitation was associated with significantly greater increases in BMI, waist circumference, and total cholesterol, associated with dietary change in women and decreased physical activity in men. In mothers, waist girth increased by 8.0 cm (0.1) compared with 3.5 cm (0.6) in women without children (P = 0.003), and physical fitness decreased [-0.5 W/kg (0.4) vs. 1.2 W/kg (0.2), respectively; P = 0.001]. CONCLUSION: Encouragement of a healthy lifestyle, particularly physical activity, should be a priority in this age group, particularly among newly cohabiting couples and in young mothers.

Adolescent↗

PubMed2006

Habitual physical activity and sedentary behaviour in a clinical sample of obese children.

OBJECTIVE: To objectively measure habitual physical activity and sedentary behaviour in a clinical sample of obese children and to compare with age- and sex-matched non-obese controls. DESIGN: Pairwise comparison of obese children matched for age and gender with non-obese controls. SUBJECTS: A total of 116 obese children (body mass index (BMI)> or =98th centile) and 53 non-obese control children (BMI<85th centile). Controls were matched with 53 of the obese children (mean age 8.6, s.d. 2.0 years; 25 M and 28 F). MEASUREMENT: Habitual physical activity and sedentary behaviour were measured over a 7-day period using CSA accelerometers. Total physical activity (mean accelerometry count per minute (c.p.m.)), percentage of monitored time in sedentary behaviour, light and moderate to vigorous intensity physical activity (MVPA) were compared. RESULTS: Obese children (n=116) spent on average 80.4% of their monitored time in sedentary behaviour and 2.5% of their monitored time in MVPA. Total activity (mean c.p.m.) was significantly higher in the non-obese group (n=53) than the obese group (n=53), 729 vs 648 c.p.m.; 95% confidence interval (CI) 7, 155. Time spent in sedentary behaviour averaged 80.9% (s.d. 6.6) in the obese group and 79.3% (s.d. 6.2) in the non-obese group, with no significant between-group difference (95% CI -3.9, 0.6). Light intensity activity was similar in the obese and non-obese groups (15.9 vs 17.3%; 95% CI -0.3, 3.0). Participation in MVPA was significantly higher in the non-obese vs obese group (3.9 vs 2.4%; 95% CI 0.6, 2.0). CONCLUSION: This study supports the hypothesis that a clinical sample of obese children is less physically active than non-obese children, although the difference in total activity and MVPA between the groups was small.

Acceleration↗

PubMed1995

Personal health benefits of Masters athletics competition.

Questionnaires (750 respondents, 44.4% response rate) examined the long-term health value of endurance exercise training in older age-classed competitors ('Masters Athletes', 551 men and 199 women) over a 7-year period (1985-1992). The majority had initially completed maximal exercise tests. The weekly time devoted to training, competition and exercise-related travel was 10 to 30 h, and the annual expenditure on clothing, equipment and entrance fees was typically in the range Canadian $500-1500. Despite their age (mean(s.d.) 58(10), current range 40-81 years), only 1.4% reported sustaining a non-fatal heart attack and 0.6% had required bypass surgery over the 7-year interval. The majority (90%) were very interested in good health; 76% considered themselves as less vulnerable to viral illnesses than their peers, and 68% regarded their quality of life as much better than that of their sedentary friends. The majority of former smokers had stopped smoking before they began training, but 37% indicated that exercise had helped them in smoking withdrawal. In keeping with their health-conscious attitude, 59% had regular medical check-ups, and 86% obeyed legislation requiring use of a seat-belt when driving. In contrast with many older people, 88% slept well or very well. Slightly over half of the sample (57%) had sustained some injury which had limited their training for one or more weeks over the 7-year study. Although participation in Masters competition appears to carry considerable health benefits, gains may in part reflect an overall healthy lifestyle.

Adult↗

PubMed2006

Invasive advance of an advantageous mutation: nucleation theory.

For sedentary organisms with localized reproduction, spatially clustered growth drives the invasive advance of a favorable mutation. We model competition between two alleles where recurrent mutation introduces a genotype with a rate of local propagation exceeding the resident's rate. We capture ecologically important properties of the rare invader's stochastic dynamics by assuming discrete individuals and local neighborhood interactions. To understand how individual-level processes may govern population patterns, we invoke the physical theory for nucleation of spatial systems. Nucleation theory discriminates between single-cluster and multi-cluster dynamics. A sufficiently low mutation rate, or a sufficiently small environment, generates single-cluster dynamics, an inherently stochastic process; a favorable mutation advances only if the invader cluster reaches a critical radius. For this mode of invasion, we identify the probability distribution of waiting times until the favored allele advances to competitive dominance, and we ask how the critical cluster size varies as propagation or mortality rates vary. Increasing the mutation rate or system size generates multi-cluster invasion, where spatial averaging produces nearly deterministic global dynamics. For this process, an analytical approximation from nucleation theory, called Avrami's Law, describes the time-dependent behavior of the genotype densities with remarkable accuracy.

Cluster Analysis↗

PubMed1997

Can we identify who will adhere to long-term physical activity? Signal detection methodology as a potential aid to clinical decision making.

Signal detection methodology was used to identify the best combination of predictors of long-term exercise adherence in 269 healthy, initially sedentary adults ages 50-65 years. Less educated individuals who were assigned to supervised home-based exercise of either higher or lower intensity and who were less stressed and less fit at baseline than other individuals had the greatest probability of successful adherence by the 2nd year. Overweight individuals assigned to a group-based exercise program were the least likely to be successful 2 years later. Predictors of short-term (1-year) adherence were generally similar to predictors of 2-year adherence. Signal detection analysis may be useful for identifying subgroups of people at risk for underadherence who subsequently might be targeted for intervention.

Aged↗

PubMed2000

Charting the physical activity patterns of contemporary children and adolescents.

The impact of physical inactivity on health is well accepted throughout the medical and health service community. However, the case has largely been established through epidemiological studies with adults. Substantial attention has been paid to the activity levels of children and adolescents, largely because of changing lifestyles that have threatened the opportunity to be active and also introduced attractive sedentary alternatives such as playing computer games. The research evidence that children have become less active to the point where it is seriously damaging their current and future health has been difficult to establish. This situation is due to difficulties in establishing sensitive health risk markers, and also with the assessment of the different elements of physical activity which in children and adolescents is a complex profile of social behaviours. Self report of activity is unreliable with young children, and objective measures are required that are cheap and effective with large samples and that are capable of measuring levels, volume and patterns of physical activity. Accelerometry in combination with diaries offers the best current solution for most activity-health relationships, and for informing intervention need and design.

Adolescent↗