The effects of aerobic and anaerobic training on fitness, blood pressure, and psychological stress and well-being

Aerobic exercise training reduces cannabis craving and use in non-treatment seeking cannabis-dependent adults

BACKGROUND

Cannabis dependence is a significant public health problem. Because there are no approved medications for this condition, treatment must rely on behavioral approaches empirically complemented by such lifestyle change as exercise.

AIMS

To examine the effects of moderate aerobic exercise on cannabis craving and use in cannabis dependent adults under normal living conditions.

DESIGN

Participants attended 10 supervised 30-min treadmill exercise sessions standardized using heart rate (HR) monitoring (60-70% HR reserve) over 2 weeks. Exercise sessions were conducted by exercise physiologists under medical oversight.

PARTICIPANTS

Sedentary or minimally active non-treatment seeking cannabis-dependent adults (n = 12, age 25±3 years, 8 females) met criteria for primary cannabis dependence using the Substance Abuse module of the Structured Clinical Interview for DSM-IV (SCID).

MEASUREMENTS

Self-reported drug use was assessed for 1-week before, during, and 2-weeks after the study. Participants viewed visual cannabis cues before and after exercise in conjunction with assessment of subjective cannabis craving using the Marijuana Craving Questionnaire (MCQ-SF).

FINDINGS

Daily cannabis use within the run-in period was 5.9 joints per day (SD = 3.1, range 1.8-10.9). Average cannabis use levels within the exercise (2.8 joints, SD = 1.6, range 0.9-5.4) and follow-up (4.1 joints, SD = 2.5, range 1.1-9.5) periods were lower than during the run-in period (both P<.005). Average MCQ factor scores for the pre- and post-exercise craving assessments were reduced for compulsivity (P  = .006), emotionality (P  = .002), expectancy (P  = .002), and purposefulness (P  = .002).

CONCLUSIONS

The findings of this pilot study warrant larger, adequately powered controlled trials to test the efficacy of prescribed moderate aerobic exercise as a component of cannabis dependence treatment. The neurobiological mechanisms that account for these beneficial effects on cannabis use may lead to understanding of the physical and emotional underpinnings of cannabis dependence and recovery from this disorder.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00838448].

Worksite physical activity interventions and obesity: a review of European studies (the HOPE project)

OBJECTIVE

Our aim was to review the effectiveness of physical activity promotion interventions in the worksite setting in Europe in order to identify those studies that had measured obesity-related outcomes and to evaluate how external validity of the findings had been assessed.

METHODS

We conducted a review of studies conducted in Europe, published up to December 2009. We assessed levels of evidence regarding effectiveness and analysed external validity using the RE-AIM framework.

RESULTS

Studies included (n = 33) were divided in 6 intervention categories. Moderate evidence of effectiveness was found for physical fitness outcomes with exercise training interventions and for physical activity outcomes with active commuting interventions. There was no or inconclusive evidence for obesity-related outcomes for all intervention categories. For external validity, elements receiving the least attention (<20%) were representativeness of participants, setting-level inclusion/exclusion criteria and representativeness, characteristics regarding intervention staff, implementation of intervention, costs, long-term effects and programme sustainability.

CONCLUSIONS

Active commuting and exercise training appear as promising approaches to promote physical activity or fitness in the workplace. The effect of interventions on obesity-related outcomes remains to be further investigated. There is a need to better report elements of generalizability and dissemination for translation into practice of worksite physical activity interventions.

Aerobic exercise training programmes for improving physical and psychosocial health in adults with Down syndrome

BACKGROUND

Although physical fitness has been suggested to improve physical and psychosocial health for a variety of population profiles, there is a lack of information about the safety and effectiveness of aerobic exercise for adults with Down syndrome.

OBJECTIVES

To evaluate the effectiveness and safety of aerobic exercise training programmes for physiological and psychosocial outcomes in adults with Down syndrome.

SEARCH STRATEGY

The following electronic databases were searched: The Cochrane Central Register of Controlled Trials (CENTRAL) (2009, Issue 1); MEDLINE (1966 to August 2009); EMBASE (1980 to August 2009); CINAHL (1982 to August 2009); LILACS (1982 to August 2009); PsycINFO (1887 to August 2009); ERIC (1966 to August 2009); Current Controlled Trials (August 2009); and Campbell Collaboration's Social, Psychological, Educational and Criminological Register (C2- SPECTR) (to August 2009). Information about ongoing clinical trials was sought by searching ClinicalTrials.gov (http://clinicaltrials.gov) (accessed August 2009), and the National Research Register (NRR) (2009 Issue 1).

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials using supervised aerobic exercise training programmes with behavioral components accepted as co-interventions.

DATA COLLECTION AND ANALYSIS

Two reviewers selected relevant trials, assessed methodological quality and extracted data. Where appropriate, data were pooled using meta-analysis with a random-effects model. Positive values favour the intervention group, while negative values favour the control group.

MAIN RESULTS

Three studies included in this systematic review used different kinds of aerobic activity: walking/jogging and rowing training and included participants with a broad age range (17 to 65 years). They were conducted in the USA, Portugal and Israel. In the meta-analyses, only maximal treadmill grade was improved after aerobic exercise training programmes (4.26 grades (%) [95% CI 2.06, 6.45]). Other variables relative to work performance that could not be combined in a meta-analysis were also improved in the intervention group (maximal test time P=0.0003), total turns of fan wheel (P=0.02), resistance of ergometer (p=0.003), power knee extension and flexion (p<0.00001), and timed up and go test (p=0.008). Thirty other outcomes measured in this review including, oxidative stress and body composition variables, could not be combined in the meta-analysis. Apart from work performance, trials reported no statistically significant improvements.

AUTHORS' CONCLUSIONS

There is insufficient evidence to demonstrate that there is improvement in physical or psychosocial outcomes of aerobic exercise in adults with Down syndrome. Although evidence exists to support improvements in physiological and psychological aspects from strategies using mixed physical activity programmes, well-conducted research examining long-term physical outcomes, adverse effects, psychosocial outcomes and costs is required before informed practice decisions can be made.

Is insufficient quantity and quality of sleep a risk factor for neck, shoulder and low back pain? A longitudinal study among adolescents

The quantity and quality of adolescents' sleep may have changed due to new technologies. At the same time, the prevalence of neck, shoulder and low back pain has increased. However, only a few studies have investigated insufficient quantity and quality of sleep as possible risk factors for musculoskeletal pain among adolescents. The aim of the study was to assess whether insufficient quantity and quality of sleep are risk factors for neck (NP), shoulder (SP) and low back pain (LBP). A 2-year follow-up survey among adolescents aged 15-19 years was (2001-2003) carried out in a subcohort of the Northern Finland Birth Cohort 1986 (n = 1,773). The outcome measures were 6-month period prevalences of NP, SP and LBP. The quantity and quality of sleep were categorized into sufficient, intermediate or insufficient, based on average hours spent sleeping, and whether or not the subject suffered from nightmares, tiredness and sleeping problems. The odds ratios (OR) and 95% confidence intervals (CI) for having musculoskeletal pain were obtained through logistic regression analysis, adjusted for previously suggested risk factors and finally adjusted for specific pain status at 16 years. The 6-month period prevalences of neck, shoulder and low back pain were higher at the age of 18 than at 16 years. Insufficient quantity or quality of sleep at 16 years predicted NP in both girls (OR 4.4; CI 2.2-9.0) and boys (2.2; 1.2-4.1). Similarly, insufficient sleep at 16 years predicted LBP in both girls (2.9; 1.7-5.2) and boys (2.4; 1.3-4.5), but SP only in girls (2.3; 1.2-4.4). After adjustment for pain status, insufficient sleep at 16 years predicted significantly only NP (3.2; 1.5-6.7) and LBP (2.4; 1.3-4.3) in girls. Insufficient sleep quantity or quality was an independent risk factor for NP and LBP among girls. Future studies should test whether interventions aimed at improving sleep characteristics are effective in the prevention and treatment of musculoskeletal pain.

Meta-analysis of workplace physical activity interventions

CONTEXT

Most adults do not achieve adequate physical activity levels. Despite the potential benefits of worksite health promotion, no previous comprehensive meta-analysis has summarized health and physical activity behavior outcomes from such programs. This comprehensive meta-analysis integrated the extant wide range of worksite physical activity intervention research.

EVIDENCE ACQUISITION

Extensive searching located published and unpublished intervention studies reported from 1969 through 2007. Results were coded from primary studies. Random-effects meta-analytic procedures, including moderator analyses, were completed in 2008.

EVIDENCE SYNTHESIS

Effects on most variables were substantially heterogeneous because diverse studies were included. Standardized mean difference (d) effect sizes were synthesized across approximately 38,231 subjects. Significantly positive effects were observed for physical activity behavior (0.21); fitness (0.57); lipids (0.13); anthropometric measures (0.08); work attendance (0.19); and job stress (0.33). The significant effect size for diabetes risk (0.98) is less robust given small sample sizes. The mean effect size for fitness corresponds to a difference between treatment minus control subjects' means on VO2max of 3.5 mL/kg/min; for lipids, -0.2 on the ratio of total cholesterol to high-density lipoprotein; and for diabetes risk, -12.6 mg/dL on fasting glucose.

CONCLUSIONS

These findings document that some workplace physical activity interventions can improve both health and important worksite outcomes. Effects were variable for most outcomes, reflecting the diversity of primary studies. Future primary research should compare interventions to confirm causal relationships and further explore heterogeneity.

Physical activity, job demand-control, perceived stress-energy, and salivary cortisol in white-collar workers

PURPOSE

The aim of the present study is to examine the association between physical activity and perceived job demand, job control, perceived stress and energy, and physiological arousal reflected by morning and evening concentrations of cortisol in saliva among white-collar workers.

METHODS

Physical activity during the last week was assessed during work and leisure time by a Danish version of the International Physical Activity Questionnaire and saliva samples were collected. The study group comprised 389 white-collar workers, aged 25-67 years, and of which 257 were women.

RESULTS

We found that physical activity during leisure time was associated with higher perceived energy, and for men also with lower perceived stress. Further, we found that physical activity at leisure time affected the association between salivary cortisol and perceived stress and energy so that respondents being physically active at leisure time and perceiving higher energy showed higher evening saliva cortisol.

CONCLUSION

Physically active employees perceive less stress and more energy. The association between stress-energy and salivary cortisol was affected by vigorous physical activity. No association between job control-demand and the degree of physical activity was found. Based on the present data, we recommend office workers-exposed to high job strain and inactivity at the job-to perform physical activity, preferably of high intensity, in order to reduce stress and increase energy.

WITHDRAWN: Aerobic exercise training programmes for improving physical and psychosocial health in adults with Down syndrome

BACKGROUND

Although physical fitness has been suggested to improve physical and psychosocial health for a variety of population profiles, there is a lack of information about the safety and effectiveness of aerobic exercise for adults with Down syndrome.

OBJECTIVES

To evaluate the effectiveness and safety of aerobic exercise training programmes for physiological and psychosocial outcomes in adults with Down syndrome.

SEARCH STRATEGY

Search terms and synonyms for "aerobic exercise" and "Down syndrome" were used within the following databases: CENTRAL (2007, Issue 1); MEDLINE via PUBMED (1966 to March 2007); EMBASE (2005 to April 2007); CINAHL (1982 to March 2007); LILACS (1982 to March 2007); PsycINFO (1887 to March 2007); ERIC (1966 to March 2007); CCT (March 2007); Academic Search Elite (to March 2007), C2- SPECTR (to March 2007 ), NRR (2007 Issue 1), ClinicalTrials.gov (accessed March 2007) and within supplements of Medicine and Science in Sports and Exercise.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials using supervised aerobic exercise training programmes with behavioral components accepted as co-interventions.

DATA COLLECTION AND ANALYSIS

Two reviewers selected relevant trials, assessed methodological quality and extracted data. Where appropriate, data was pooled using meta-analysis with a random effects model

MAIN RESULTS

The two studies included in this trial used different kinds of aerobic activity: walking/jogging and rowing training. One included study was conducted in the USA, the other in Portugal. In the meta-analyses, only maximal treadmill grade, a work performance variable, was improved in the intervention group after aerobic exercise training programmes (-4.26 [95% CI -6.45, -2.06]) grade. The other outcomes in the meta-analysis showed no significant differences between intervention and control groups, as expressed by weighted mean difference: VO(2) peak -0.30 (95% CI -377, 3.17) mL.Kg.min(-1); peak heart rate, -2.84 (95% CI -10.73, 5.05) bpm; respiratory exchange ratio, 0.01 (95% CI -0.04, 0.06); pulmonary ventilation, -5.86 (95% CI -16.06, 4.34) L.min(-1). 30 other measures including work performance, oxidative stress and body composition variables could not be combined in the meta-analysis. Apart from work performance, trials reported no significant improvements in these measures.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support improvement in physical or psychosocial outcomes of aerobic exercise in adults with Down syndrome. Although evidence exists which supports improvements in physiological and psychological aspects from strategies using mixed physical activity programmes, well-conducted research which examines long-term physical outcomes, adverse effects, psychosocial outcomes and costs are required before informed practice decisions can be made.

American College of Sports Medicine Position Stand. Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults

Overweight and obesity affects more than 66% of the adult population and is associated with a variety of chronic diseases. Weight reduction reduces health risks associated with chronic diseases and is therefore encouraged by major health agencies. Guidelines of the National Heart, Lung, and Blood Institute (NHLBI) encourage a 10% reduction in weight, although considerable literature indicates reduction in health risk with 3% to 5% reduction in weight. Physical activity (PA) is recommended as a component of weight management for prevention of weight gain, for weight loss, and for prevention of weight regain after weight loss. In 2001, the American College of Sports Medicine (ACSM) published a Position Stand that recommended a minimum of 150 min wk(-1) of moderate-intensity PA for overweight and obese adults to improve health; however, 200-300 min wk(-1) was recommended for long-term weight loss. More recent evidence has supported this recommendation and has indicated more PA may be necessary to prevent weight regain after weight loss. To this end, we have reexamined the evidence from 1999 to determine whether there is a level at which PA is effective for prevention of weight gain, for weight loss, and prevention of weight regain. Evidence supports moderate-intensity PA between 150 and 250 min wk(-1) to be effective to prevent weight gain. Moderate-intensity PA between 150 and 250 min wk(-1) will provide only modest weight loss. Greater amounts of PA (>250 min wk(-1)) have been associated with clinically significant weight loss. Moderate-intensity PA between 150 and 250 min wk(-1) will improve weight loss in studies that use moderate diet restriction but not severe diet restriction. Cross-sectional and prospective studies indicate that after weight loss, weight maintenance is improved with PA >250 min wk(-1). However, no evidence from well-designed randomized controlled trials exists to judge the effectiveness of PA for prevention of weight regain after weight loss. Resistance training does not enhance weight loss but may increase fat-free mass and increase loss of fat mass and is associated with reductions in health risk. Existing evidence indicates that endurance PA or resistance training without weight loss improves health risk. There is inadequate evidence to determine whether PA prevents or attenuates detrimental changes in chronic disease risk during weight gain.

Aerobic exercise decreases the positive-reinforcing effects of cocaine

Aerobic exercise can serve as an alternative, non-drug reinforcer in laboratory animals and has been recommended as a potential intervention for substance abusing populations. Unfortunately, relatively little empirical data have been collected that specifically address the possible protective effects of voluntary, long-term exercise on measures of drug self-administration. The purpose of the present study was to examine the effects of chronic exercise on sensitivity to the positive-reinforcing effects of cocaine in the drug self-administration procedure. Female rats were obtained at weaning and immediately divided into two groups. Sedentary rats were housed individually in standard laboratory cages that permitted no exercise beyond normal cage ambulation; exercising rats were housed individually in modified cages equipped with a running wheel. After 6 weeks under these conditions, rats were surgically implanted with venous catheters and trained to self-administer cocaine on a fixed-ratio schedule of reinforcement. Once self-administration was acquired, cocaine was made available on a progressive ratio schedule and breakpoints were obtained for various doses of cocaine. Sedentary and exercising rats did not differ in the time to acquire cocaine self-administration or responding on the fixed-ratio schedule of reinforcement. However, on the progressive ratio schedule, breakpoints were significantly lower in exercising rats than sedentary rats when responding was maintained by both low (0.3mg/kg/infusion) and high (1.0mg/kg/infusion) doses of cocaine. In exercising rats, greater exercise output prior to catheter implantation was associated with lower breakpoints at the high dose of cocaine. These data indicate that chronic exercise decreases the positive-reinforcing effects of cocaine and support the possibility that exercise may be an effective intervention in drug abuse prevention and treatment programs.

Psychosocial interventions for prevention of psychological disorders in law enforcement officers

BACKGROUND

Psychosocial interventions are widely used for the prevention of psychological disorders in law enforcement officers.

OBJECTIVES

To assess the effectiveness and comparative effectiveness of psychosocial interventions for the prevention of psychological disorders in law enforcement officers.

SEARCH STRATEGY

CCDANCTR-References was searched on 12/5/2008, electronic databases were searched, reference lists of review articles and included studies were checked, a specialist journal was handsearched, specialist books were checked and we contacted experts and trialists.

SELECTION CRITERIA

Randomised and quasi randomised controlled trials were eligible. The types of participants were people employed directly in law enforcement, including police officers and military police, regardless of gender, age and country of origin, and whether or not they had experienced some psychological trauma. All types of psychosocial intervention were eligible. The relevant outcome measures were psychological symptoms, adverse events and acceptability of interventions.

DATA COLLECTION AND ANALYSIS

Data was entered into Review Manager 4.2 for analysis, but this review was converted to RevMan 5.0 for publication. Quality assessments were performed. Two authors independently selected studies, extracted data and assessed the quality of studies. Summary effects were to be calculated using RevMan but no meta-analyses were possible. For individual studies, dichotomous outcome data are presented using relative risk, and continuous outcome data are presented using the weighted mean difference. These results are given with their 95% confidence intervals (CI).

MAIN RESULTS

Ten studies were included in the review but only five reported data that could be used. Three of the ten studies were related to exercise-based psychological interventions. Seven were related to psychological interventions. No meta-analyses were possible due to diversity of participants, interventions and outcomes. Two studies compared a psychosocial intervention versus another intervention. Three studies compared a psychosocial intervention to a control group. Only one primary prevention trial reported data for the primary outcomes and, although this study found a significant difference in depression in favour of the intervention at endpoint, this difference was no longer evident at 18 months. No studies of primary prevention comparing different interventions and reporting primary outcomes of interest were identified. The methodological quality of the included studies was summarised. No study met our full quality criteria and one was regarded as low-quality. The remainder could not be rated because of incomplete data in the published reports and inadequate responses from the trialists.

AUTHORS' CONCLUSIONS

There is evidence only from individual small and low quality trials with minimal data suggesting that police officers benefit from psychosocial interventions, in terms of physical symptoms and psychological symptoms such as anxiety, depression, sleep problems, cynicism, anger, PTSD, marital problems and distress. No data on adverse effects were available. Meta-analyses of the available data were not possible. Further well-designed trials of psychosocial interventions are required. Research is needed on organization-based interventions to enhance psychological health among police officers.

Physical activity level and health-related quality of life in the general adult population: a systematic review

OBJECTIVE

Little is known regarding health-related quality of life and its relation with physical activity level in the general population. Our primary objective was to systematically review data examining this relationship.

METHODS

We systematically searched MEDLINE, EMBASE, CINAHL, and PsycINFO for health-related quality of life and physical activity related keywords in titles, abstracts, or indexing fields.

RESULTS

From 1426 retrieved references, 55 citations were judged to require further evaluation. Fourteen studies were retained for data extraction and analysis; seven were cross-sectional studies, two were cohort studies, four were randomized controlled trials and one used a combined cross sectional and longitudinal design. Thirteen different methods of physical activity assessment were used. Most health-related quality of life instruments related to the Medical Outcome Study SF-36 questionnaire. Cross-sectional studies showed a consistently positive association between self-reported physical activity and health-related quality of life. The largest cross-sectional study reported an adjusted odds ratio of "having 14 or more unhealthy days" during the previous month to be 0.40 (95% Confidence Interval 0.36-0.45) for those meeting recommended levels of physical activity compared to inactive subjects. Cohort studies and randomized controlled trials tended to show a positive effect of physical activity on health-related quality of life, but similar to the cross-sectional studies, had methodological limitations.

CONCLUSION

Cross-sectional data showed a consistently positive association between physical activity level and health-related quality of life. Limited evidence from randomized controlled trials and cohort studies precludes a definitive statement about the nature of this association.

Does aerobic training enhance effects of spa therapy in back pain patients? A randomized, controlled clinical trial

OBJECTIVES

The aim of the present study was to evaluate the effects of 3 weeks of individualized aerobic exercise training combined with conventional spa therapy on patients' assessment of chronic pain and quality of life.

PATIENTS AND METHODS

44 patients of either sex and advanced age (50-70 years) with chronic pain underwent an inpatient spa therapy in Bad Tatzmannsdorf, Austria. Participants were randomized into 2 groups, a control group receiving spa therapy alone, and a training group carrying out an additional aerobic training. Every participant performed an exhaustive bicycle exercise test at the beginning of the study. Subsequently, participants of the training group performed individualized training programs, controlled and documented by ambulatory heart rate monitors. At the beginning and the end of the study the following outcome measures were assessed by use of questionnaires: positive and negative mood, general depression, health satisfaction, general pain, exhaustion, abdominal complaints, and cardiac pain. The results of the questionnaires were analyzed by use of a MANOVA to evaluate differences between the two groups.

RESULTS

We observed positive effects in all participants and on all parameters investigated after 3 weeks of spa therapy. However, no significant differences could be demonstrated between the two groups (all p > 0.05).

CONCLUSION

Individualized aerobic training does not seem to enhance beneficial effects of a 3-week spa therapy on chronic pain and quality of life.

O condicionamento aeróbico e sua influência na resposta ao estresse mental em oficiais do Exército

O estresse, ao mesmo tempo em que promove a adaptação do ser humano a diferentes situações, em níveis elevados ou se mantidos por longos períodos pode produzir conseqüências para o organismo, acarretando diversos problemas à saúde do indivíduo. A prática de exercício físico e elevada capacidade cardiorrespiratória parecem gerar proteção contra os efeitos indesejados do estresse. O objetivo deste trabalho foi verificar o efeito do condicionamento físico aeróbico na resposta psicofisiológica a estressores laboratoriais em oficiais do Exército Brasileiro. Para tal, 438 militares realizaram o teste de 12 minutos de Cooper, a fim de avaliar a sua condição cardiorrespiratória. Depois, entre os que percorreram mais de 3.200m (VO2max estimado de 63,01 ± 2,73ml.kg¹.min¹) e menos do que 2.400m (VO2max estimado de 38,7 ± 1,68ml.kg¹.min¹), foram selecionados 28 militares, divididos igualmente em dois grupos denominados, respectivamente, de condicionamento superior (GSUP) e de condicionamento inferior (GINF). Após uma medida inicial em repouso, foram aplicados nos sujeitos dois estressores laboratoriais consecutivos, cold stressor e estressor matemático, enquanto se mensurava o nível de condutibilidade da pele (NCP) dos mesmos. Anteriormente ao início dos estressores, os grupos não apresentavam diferença entre si e, quando da aplicação destes, o GSUP apresentou menores valores de NCP que o GINF durante o cold stressor (9,29 ± 0,06µS e 9,40 ± 0,04µS; p = 0,009, respectivamente) e durante o estressor matemático (9,29 ± 0,07µS e 9,39 ± 0,07µS; p = 0,012, respectivamente). Os resultados sugerem que indivíduos com melhor condição cardiorrespiratória tendem a apresentar padrões reduzidos na resposta autonômica ao estresse, como indicado pelo comportamento dos níveis de condutibilidade na pele.

Effect of intermittent high-intensity compared with continuous moderate exercise on glucose production and utilization in individuals with type 1 diabetes

Previously, the decline in glycemia in individuals with type 1 diabetes has been shown to be less with intermittent high-intensity exercise (IHE) compared with continuous moderate-intensity exercise (MOD) despite the performance of a greater amount of total work. The purpose of the present study was to determine whether this lesser decline in glycemia can be attributed to a greater increment in endogenous glucose production (Ra) or attenuated glucose utilization (Rd). Nine individuals with type 1 diabetes were tested on two separate occasions, during which either a 30-min MOD or IHE protocol was performed under conditions of a euglycemic clamp in combination with the infusion of [6,6-(2)H]glucose. MOD consisted of continuous cycling at 40% VO2 peak, whereas IHE involved a combination of continuous exercise at 40% VO2 peak interspersed with additional 4-s maximal sprint efforts performed every 2 min to simulate the activity patterns of intermittent sports. During IHE, glucose Ra increased earlier and to a greater extent compared with MOD. Similarly, glucose Rd increased sooner during IHE, but the increase by the end of exercise was comparable with that elicited by MOD. During early recovery from IHE, Rd rapidly declined, whereas it remained elevated after MOD, a finding consistent with a lower glucose infusion rate during early recovery from IHE compared with MOD (P<0.05). The results suggest that the lesser decline in glycemia with IHE may be attributed to a greater increment in Ra during exercise and attenuated Rd during exercise and early recovery.

Cardiorespiratory fitness and laboratory stress: a meta-regression analysis

We performed a meta-regression analysis of 73 studies that examined whether cardiorespiratory fitness mitigates cardiovascular responses during and after acute laboratory stress in humans. The cumulative evidence indicates that fitness is related to slightly greater reactivity, but better recovery. However, effects varied according to several study features and were smallest in the better controlled studies. Fitness did not mitigate integrated stress responses such as heart rate and blood pressure, which were the focus of most of the studies we reviewed. Nonetheless, potentially important areas, particularly hemodynamic and vascular responses, have been understudied. Women, racial/ethnic groups, and cardiovascular patients were underrepresented. Randomized controlled trials, including naturalistic studies of real-life responses, are needed to clarify whether a change in fitness alters putative stress mechanisms linked with cardiovascular health.

A school-based physical activity program to improve health and fitness in children aged 6-13 years ("Kinder-Sportstudie KISS"): study design of a randomized controlled trial [ISRCTN15360785]

BACKGROUND

Childhood obesity is the result of a long lasting imbalance between energy intake and energy expenditure. A major contributing factor is physical inactivity which is closely linked to bone health, cardiovascular disease risk, fitness and psychological factors. The school seems to provide an excellent setting to enhance levels of physical activity (PA). However, there is insufficient data from previous school-based intervention trials on how to enhance overall PA. It is also unknown whether an intervention aimed at increasing PA is effective in improving the children's health. The purpose of this paper is to outline the design of a school-based randomized, controlled trial (RCT) aiming to increase overall PA and to improve fitness and health in 6- to 13-year-old children.

METHODS/DESIGN

15 schools were randomized to the intervention (n = 9) or the control (n = 6) group, stratified by geographic region (urban vs. rural) and by age (1st and 5th grade). Participation was given for all children in the intervention group since in this group the intervention was part of the normal school curriculum. The intervention during one academic year consisted of: 1. two additional physical education classes per week given by trained physical education teachers adding up to a total of five PA classes per week, 2. short PA breaks (2-5 min each) during academic lessons, 3. PA home work, and 4. adaptation of recreational areas around the school. All children underwent anthropometric measurements, blood pressure assessment, fitness testing, measurement of PA and they filled out questionnaires. At least 70% of all children agreed to blood sampling and measurements of body composition and bone mineral measurements by dual energy x-ray absorptiometry. The primary endpoints of the study after one year were an increase in total PA by accelerometry, an increase in aerobic fitness measured by the 20 m shuttle run, a decrease in percent body fat derived from skinfold measurements and an increase in quality of life as assessed by the child health questionnaire in the intervention group compared to the control group. Secondary outcomes were overall fitness, differences in body composition including body fat distribution, cardiovascular risk factors, psychosocial health, bone mineral content and density of femur, lumbar spine and total body and food intake.

DISCUSSION

Our preliminary data suggest that the children were representative of Swiss children with respect to sex, socio-demographic status, and body mass index. Short-term results can be expected by the beginning of 2007. We hypothesized that our intervention will lead to an increase in PA, fitness and overall health. Based on our data, we aim to provide important information regarding the influence of such an intervention on these outcome measures in school-aged children and to provide nationwide guidelines to improve PA in children.

Physical activity counseling in primary care and patient well-being: Do patients benefit?

BACKGROUND

Promoting physical activity is an important public health strategy for long-term reductions in incidence or severity of clinical disease. Benefits to health-related quality of life (HRQL) and subjective well-being may be as important and take less time to accrue.

PURPOSE

We examined the HRQL benefits of a social-cognitive-theory-based intervention of the Activity Counseling Trial (ACT), both directly in terms of changes in physical fitness and indirectly from increased self-efficacy associated with the intervention.

METHODS

In ACT, 395 female and 479 male inactive patients ages 35 to 75 years were randomized to one of: physician advice, advice plus behavioral counseling during primary care visits, or advice plus behavioral counseling that also included telephone contact and behavioral classes. Participants were assessed at baseline, 6 months, and 24 months. HRQL was assessed as perceived quality of life, perceived stress, depression, and general health. Satisfaction with function and appearance, self-efficacy, and social support were also assessed.

RESULTS

At 24 months women who received counseling or assistance had significant reductions in daily stress and improvements in satisfaction with body function compared to those receiving advice only. Men had reductions in daily stress across all treatment arms. These results mirrored VO2max changes observed per group. Change in barriers self-efficacy was significantly associated with reductions in daily stress at 24 months.

CONCLUSIONS

Patient benefit from ACT intervention was mediated by enhanced cardiorespiratory fitness and by barriers self-efficacy.

Aerobic exercise training programmes for improving physical and psychosocial health in adults with Down syndrome

BACKGROUND

Although physical fitness has been suggested to improve physical and psychosocial health for a variety of population profiles, there is a lack of information about the safety and effectiveness of aerobic exercise for adults with Down syndrome.

OBJECTIVES

To evaluate the effectiveness and safety of aerobic exercise training programmes for physiological and psychosocial outcomes in adults with Down syndrome.

SEARCH STRATEGY

Search terms and synonyms for "aerobic exercise" and "Down syndrome" were used within the following databases:CENTRAL (2005, Issue 2); MEDLINE (1966 to March 2005); EMBASE (2005 to April 2005); CINAHL (1982 to March 2005); LILACS (1982 to March 2005); PsycINFO (1887 to March 2005); ERIC (1966 to March 2005); CCT (March 2005); Academic Search Elite (to March 2005), C2- SPECTR (to March 2005 ), NRR (2005 Issue 1), ClinicalTrials.gov (accessed March 2005)and within supplements of Medicine and Science in Sports and Exercise.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials using supervised aerobic exercise training programmes with behavioral components accepted as co-interventions.

DATA COLLECTION AND ANALYSIS

Two reviewers selected relevant trials, assessed methodological quality and extracted data. Where appropriate, data was pooled using meta-analysis with a random effects model

MAIN RESULTS

The two studies included in this trial used different kinds of aerobic activity: walking/jogging and rowing training. One included study was conducted in the USA, the other in Portugal. In the meta-analyses, only maximal treadmill grade, a work performance variable, was improved in the intervention group after aerobic exercise training programmes (-4.26 [95% CI -6.45, -2.06]) grade. The other outcomes in the meta-analysis showed no significant differences between intervention and control groups, as expressed by weighted mean difference: VO(2) peak -0.30 (95% CI -377, 3.17) mL.Kg.min(-1); peak heart rate, -2.84 (95% CI -10.73, 5.05) bpm; respiratory exchange ratio, 0.01 (95% CI -0.04, 0.06); pulmonary ventilation, -5.86 (95% CI -16.06, 4.34) L.min(-1). 30 other measures including work performance, oxidative stress and body composition variables could not be combined in the meta-analysis. Trials reported no significant improvements in these measures.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support improvement in physical or psychosocial outcomes of aerobic exercise in adults with Down syndrome. Although evidence exists which supports improvements in physiological and psychological aspects from strategies using mixed physical activity programmes, well-conducted research which examines long-term physical outcomes, adverse effects, psychosocial outcomes and costs are required before informed practice decisions can be made.

Effect of sporting activity on absenteeism in a working population

OBJECTIVES

To determine the effects of sporting activity on absenteeism in a working population.

METHODS

Data were used from a prospective cohort study in a working population with a follow up period of 3 years and were collected with yearly questionnaires or collected from company records. Complete data on absenteeism, sporting activity, and potential confounders were collected for 1228 workers. ANOVA was used to test differences in frequency and duration of absenteeism, correlations were computed to measure the association between number of sporting years (divided by age) and frequency and duration of absenteeism, and survival analysis, according to the Cox proportional hazards model, was used to test differences in relative risk at absenteeism and recovery. All analyses were adjusted for age, gender, smoking, and alcohol consumption, and were stratified for employees with sedentary and with more active jobs.

RESULTS

ANOVA showed a statistically significant higher mean duration of absenteeism among employees not practicing sports, of approximately 20 days over a period of 4 years. The survival analysis showed an increased relative risk at absenteeism (relative risk (RR) 1.09; confidence interval (CI) 1.01 to 1.18) and a decreased relative risk at recovery (RR 0.90; CI 0.85 to 0.95) for employees not practicing sports. The effect of sporting activity is larger in employees with sedentary work. No associations were found between number of sporting years and absenteeism.

CONCLUSION

Employees practicing sports take sick leave significantly less often than their colleagues not practicing sports, while their periods of sick leave are shorter, especially when their work is sedentary.

The decline in blood glucose levels is less with intermittent high-intensity compared with moderate exercise in individuals with type 1 diabetes

OBJECTIVE

To compare the response of blood glucose levels to intermittent high-intensity exercise (IHE) and moderate-intensity exercise (MOD) in individuals with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Seven healthy individuals with type 1 diabetes were tested on two separate occasions, during which either a 30-min MOD or IHE protocol was performed. MOD consisted of continuous exercise at 40% Vo(2peak), while the IHE protocol involved a combination of continuous exercise at 40% Vo(2peak) interspersed with 4-s sprints performed every 2 min to simulate the activity patterns of team sports.

RESULTS

Both exercise protocols resulted in a decline in blood glucose levels. However, the decline was greater with MOD (-4.4 +/- 1.2 mmol/l) compared with IHE (-2.9 +/- 0.8 mmol/l; P < 0.05), despite the performance of a greater amount of total work with IHE (P < 0.05). During 60 min of recovery from exercise, glucose levels remained higher in IHE compared with MOD (P < 0.05). Furthermore, glucose levels remained stable during recovery from IHE, while they continued to decrease after MOD (P < 0.05). The stabilization of blood glucose levels with IHE was associated with elevated levels of lactate, catecholamines, and growth hormone during early recovery from exercise (P < 0.05). There were no differences in free insulin, glucagon, cortisol, or free fatty acids between MOD and IHE.

CONCLUSIONS

The decline in blood glucose levels is less with IHE compared with MOD during both exercise and recovery in individuals with type 1 diabetes.

Disuse and deconditioning in chronic low back pain: concepts and hypotheses on contributing mechanisms

For years enhancement of a patient's level of physical fitness has been an important goal in rehabilitation treatment in chronic low back pain (CLBP), based on the hypothesis that physical deconditioning contributes to the chronicity of low back pain. However, whether this hypothesis in CLBP holds is not clear. In this paper, possible mechanisms that contribute to the development of physical deconditioning in CLBP, such as avoidance behaviour and suppressive behaviour, are discussed. The presence of both deconditioning-related physiological changes, such as muscle atrophy, changes in metabolism, osteoporosis and obesity as well as deconditioning related functional changes, such as a decrease in cardiovascular capacity, a decrease in muscle strength and impaired motor control in patients with CLBP are discussed. Results of studies on the level of physical activities in daily life (PAL) and the level of physical fitness in patients with CLBP compared to healthy controls were reviewed. In studies on PAL results that were either lower or comparable to healthy subjects were found. The presence of disuse (i.e., a decrease in the level of physical activities in daily life) in patients with CLBP was not confirmed. The inconclusive findings in the papers reviewed may partly be explained by different measurement methods used in research on PAL in chronic pain. The level of physical fitness of CLBP patients also appeared to be lower or comparable to the fitness level of healthy persons. A discriminating factor between fit and unfit patients with back pain may be the fact that fit persons more frequently are still employed, and as such may be involved more in physical activity. Lastly some suggestions are made for further research in the field of disuse and deconditioning in CLBP.

Feasibility of power-type strength training for middle aged men and women: self perception, musculoskeletal symptoms, and injury rates

OBJECTIVES

To examine the feasibility of a power-type strength training programme for middle aged men and women, the impact of the training programme on perceived health and fitness and on knee and low back symptoms, and the rate of exercise induced injuries.

METHODS

A total of 154 voluntary, healthy, sedentary men and women participated in a training programme lasting about four months. The explosive force of leg extensor muscles was measured by means of standing long jumps and vertical squat jumps. Perceived health, perceived fitness, and low back and knee symptoms were assessed before and after the intervention by using a questionnaire. Musculoskeletal disorders and exercise induced injuries were reported during the training programme.

RESULTS

Perceived fitness improved in both men (p<0.01) and women (p<0.0001), but perceived health only in women (p<0.01). Men with increased explosive force in squat jumping also showed better perceived health (p<0.05), and women with increased explosive force in standing long jump showed better perceived fitness (p<0.05). Exercising men who had increased knee symptoms had significantly higher body mass index than the other exercising men (p<0.05). The exercise induced injury rate was 19% in men and 6% in women.

CONCLUSIONS

Successful completion of the exercise programme, together with the increased physical activity and relatively low injury rate, may have contributed to the participants finding the exercise programme positive and stimulating and believing that their health and fitness had improved. The low rate of musculoskeletal injury suggests that this type of supervised exercise programme is feasible for untrained middle aged people.

Strength training and hemodynamic responses to exercise

Sixty-two older adults (68.4+/-6 years) were randomized into a control group (n=16), low-intensity exercise group (n=22, LEX; 50% 1-repetition maximum; 13 repetitions per exercise), or a high-intensity exercise group (n=24, HEX; 80% 1-repetition maximum; eight repetitions per exercise) group. Subjects trained for 24 weeks, performing 1 set for each of 13 exercises. Subjects performed a graded exercise test (GXT) at baseline and after 24 weeks of strength training. Heart rate, systolic, and diastolic blood pressures were measured at rest, during the GXT and 1, 3, and 5-min post-GXT. Mean arterial pressure was also calculated. Post-training, time to peak systolic and diastolic blood pressures and heart rate was increased in the LEX and HEX groups by 22.9% and 44.5%, respectively (p<0.05). Diastolic blood pressure, heart rate, and mean arterial pressure during the GXT were significantly decreased (p<0.05) in the HEX group following training. Post-GXT heart rate was lower in the HEX and LEX groups compared to control (p<0.05) indicating a more rapid recovery. Resistance exercise prolongs the onset of peak cardiovascular responses, decreases the cardiovascular response to exertion, and improves recovery from maximal exertion.

The effectiveness of worksite physical activity programs on physical activity, physical fitness, and health

OBJECTIVE

To critically review the literature with respect to the effectiveness of worksite physical activity programs on physical activity, physical fitness, and health.

DATA SOURCES

A search for relevant English-written papers published between 1980 and 2000 was conducted using MEDLINE, EMBASE, Sportdiscus, CINAHL, and Psychlit. The key words used involved a combination of concepts regarding type of study, study population, intervention, and outcome measure. In addition, a search was performed in our personal databases, as well as a reference search of the studies retrieved.

STUDY SELECTION

The following criteria for inclusion were used: 1) randomized, controlled trial or nonrandomized, controlled trial; 2) working population; 3) worksite intervention program to promote employees' physical activity or physical fitness; and 4) physical activity, physical fitness, or health-related outcomes.

DATA EXTRACTION

Two reviewers independently evaluated the quality of relevant studies using a predefined set of nine methodological criteria. Conclusions regarding the effectiveness of a worksite physical activity programs were based on a rating system consisting of five levels of evidence.

DATA SYNTHESIS

Fifteen randomized, controlled trials and 11 nonrandomized, controlled trials met the criteria for inclusion and were reviewed. Six randomized, controlled trials and none of the nonrandomized, controlled trials were of high methodological quality. Strong evidence was found for a positive effect of a worksite physical activity program on physical activity and musculoskeletal disorders. Limited evidence was found for a positive effect on fatigue. For physical fitness, general health, blood serum lipids, and blood pressure, inconclusive or no evidence was found for a positive effect.

CONCLUSIONS

To increase the level of physical activity and to reduce the risk of musculoskeletal disorders, we support implementation of worksite physical activity programs. For the other outcome measures, scientific evidence of the effectiveness of such a program is still limited or inconclusive, which is mainly the result of the small number of high-quality trials. Therefore, we recommend performing more randomized, controlled trials of high methodological quality, taking into account criteria such as randomization, blinding, and compliance.

Exercise reduces fatigue in chronic fatigued Hodgkins disease survivors--results from a pilot study

The aims of this pilot study were to compare aerobic capacity in non-fatigued and fatigued Hodgkin's disease survivors (HDS) and to assess the feasibility of an exercise-programme and its effects upon fatigue, physical functioning and aerobic capacity in chronic fatigued HDS. 53 HDS (85%) of originally 62 survivors treated at the Trondheim University Hospital in the period 1987-1997 completed a questionnaire including the Fatigue Questionnaire (FQ). 18 subjects were identified with chronic fatigue. 15 non-fatigued HDS matched for gender and age were drawn as controls. Both groups were invited to medical examination and exercise tests. All 15 fifteen non-fatigued HDS showed up to the medical examination. 12 of the 18 patients with chronic fatigue completed the tests and nine agreed to enter a home-based exercise intervention. Outcome measures were aerobic capacity, fatigue and physical functioning. No significant difference in aerobic capacity was found between the chronic fatigued HDS and the controls. Fatigue, physical functioning and maximal aerobic capacity were significantly improved after the intervention. Aerobic exercise had a positive effect upon chronic fatigue in HDS. However, the study is a pilot study and needs confirmation in a larger group of subjects. The intervention was well accepted, and the majority of the patients adhered to the programme.

Original metric vs. standardized effect sizes for meta-analysis of clinical data

This study compared the use of the original metric effect size with the standardized effect size for clinical data in meta-analysis. The example data set included 17 controlled clinical trials dealing with the effects of progressive resistance exercise on resting diastolic blood pressure in adults. Original metric effect size showed a decrease in resting diastolic blood pressure of -2.07 mm Hg (95% confidence interval, -3.60 to -0.54). From a clinical standpoint, this is considered a "small" effect. The standardized approach showed an average effect of -0.21, 95% CI= -0.39 to -0.02. This is also considered a "smal" effect. When possible, use of the original metric is preferred because it can be more clinically meaningful and will enhance interpretation of blood pressure results for a wider range of readers. (c) 2001 by CHF, Inc

Strength training normalizes resting blood pressure in 65- to 73-year-old men and women with high normal blood pressure

OBJECTIVE

To determine the effects of heavy resistance strength training (ST) on resting blood pressure (BP) in older men and women.

DESIGN

Prospective intervention study.

SETTING

University of Maryland Exercise Science Laboratory.

PARTICIPANTS

Twenty-one sedentary, healthy older men (69 +/- 1 year, n = 11) and women (68 +/- 1 year, n = 10) served as subjects for the study.

INTERVENTION

Six months of progressive whole body ST performed 3 days per week using Keiser K-300 air-powered resistance machines.

MEASUREMENTS

One-repetition maximum (1 RM) strength was measured for seven different exercises before and after the ST program. Resting BP was measured on six separate occasions before and after ST for each subject.

RESULTS

Substantial increases in 1 RM strength were observed for upper body (UB) and lower body (LB) muscle groups for men (UB: 215 vs 265 kg; LB: 694 vs 838 kg; P < .001) and women (UB: 128 vs 154 kg; LB: 441 vs 563 kg; P < .001). The ST program led to reductions in both systolic (131 +/- 2 vs 126 +/- 2 mm Hg, P < .010) and diastolic (79 +/- 2 vs 75 +/- 1 mm Hg, P < .010) BP. Systolic BP was reduced significantly in men (134 +/- 3 vs 127 +/- 2 mm Hg, P < .01) but not in women (128 +/- 3 vs 125 +/- 3 mm Hg, P < .01), whereas diastolic BP was reduced following training in both men (81 +/- 3 vs 77 +/- 1, mm Hg, P = .054) and women (78 +/- 2 vs 74 +/- 2 mm Hg, P = .055).

CONCLUSIONS

Six months of heavy resistance ST may reduce resting BP in older persons. According to the latest guidelines from the Joint National Committee for the Detection, Evaluation, and Treatment of Hypertension, the changes in resting BP noted in the present study represent a shift from the high normal to the normal category.

Dynamic resistance exercise and resting blood pressure in adults: a meta-analysis

With the use of the meta-analytic approach, the purpose of this study was to examine the effects of dynamic resistance exercise, i.e., weight training, on resting systolic and diastolic blood pressure in adults. A total of nine studies consisting of 259 subjects (144 exercise, 115 control) and 18 groups (9 exercise, 9 control) were included in this analysis. With the use of the bootstrap technique (10,000 samples), significant treatment effect (delta 3) reductions were found across all designs and categories for both systolic and diastolic blood pressure [systolic, mean +/- SD = -4.55 +/- 1.75 mmHg, 95% confidence interval (CI) = -1.56 to -8.56; diastolic, mean +/- SD = -3.79 + 1.12 mmHg, 95% confidence interval CI = -1.89 to -6.33]. Delta 3 changes corresponded with relative decreases of approximately 3 and 4% in resting systolic and diastolic blood pressure, respectively. In conclusion, meta-analytic review of included studies suggests that dynamic resistance exercise reduces resting systolic and diastolic blood pressure in adults. However, it is premature to form strong conclusions regarding the effects of dynamic resistance exercise on resting blood pressure. A need exists for additional, well-designed studies on this topic before a recommendation can be made regarding the efficacy of dynamic resistance exercise as a nonpharmacological therapy for reducing resting blood pressure in adults, especially in hypertensive adults.

The effect of moderate exercise on mood in mildly hypertensive volunteers: a randomized controlled trial

This study reports an investigation of the effect of participating in moderate exercise (three 40-min sessions of brisk walking a week for 6 months) on mood state in 177 sedentary, mildly hypertensive volunteers. Mood was assessed by the Profile of Mood States, Bipolar Form (POMS-BI), and no significant differences were found between control and exercise groups. The intervention group increased its exercise output more than the control group, but there was also a significant increase in exercise done by the control group. We conclude that exercise has no major effect on mood in hypertensive volunteers.

Effects of type of exercise on depression in recovering substance abusers

This experiment investigated the effects of three types of structured exercise (aerobics, bodybuilding, and circuit training) on depressive symptoms of 45 clients undergoing a 4-wk., inpatient rehabilitation program for substance abuse. Pre- and posttest measures included the Center of Epidemiological Studies--Depression, resting pulse rate, blood pressure, maximum strength on incline bench press, and estimates of aerobic fitness and body fat. The bodybuilding program produced a significant decrease in depressive symptoms. Physiological and psychological explanations are discussed.

Aerobic exercise, mood states and menstrual cycle symptoms

This study examined the effects of regular, moderate exercise on mood states and menstrual cycle symptoms. A group of female regular exercisers (N = 97), and a second group of female nonexercisers (N = 159), completed the Menstrual Distress Questionnaire (MDQ) and the Differential Emotions Scale (DES-IV) premenstrually, menstrually and intermenstrually. Multivariate analyses of covariance (MANCOVAs) revealed significant effects for exercise on negative mood states and physical symptoms, and significant effects on all measures across menstrual cycle phase. The regular exercisers obtained significantly lower scores on impaired concentration, negative affect, behaviour change and pain. No differences were found between groups on positive affect and other physical symptoms.

Impact of a health promotion programme on multiple risk factors for CHD: a preliminary evaluation

Results are reported from a pilot study to evaluate an innovative health promotion programme (Lanark Health Club), in a community where the incidence of CHD is above average. The aim of the programme is to provide multiple risk factor screening and interventions--including an exercise programme--sited in the community and utilising existing resources within primary care and the voluntary sector. Data were returned by 54 respondents after six months' participation on the programme. Subjects' self-reported activity levels increased significantly over time, and there were concomitant significant reductions in weight, SBP and DBP. Reduced levels of self-reported stress were associated with reductions in alcohol intake, and were greater in male subjects. When other measures were controlled for, stress reduction was significantly more likely for those who also lost weight and exhibited a reduction in DBP. Finally, participation in the Health Club appeared to result in cholesterol reduction, particularly for those with relatively high initial cholesterol levels. While this could reflect regression effects, it is certainly worthy of more systematic examination.

Aerobic fitness and opioidergic inhibition of cardiovascular stress reactivity

The role of endogenous opioids in aerobic fitness-induced decrements in cardiovascular stress reactivity was examined by comparing the effects of opioid antagonism with naltrexone on responses to stress in young adults with high versus low levels of aerobic fitness. Two hundred forty subjects were given an activity questionnaire and males with the highest (Fit) and lowest (Nonfit) aerobic activity profiles were recruited for maximal oxygen consumption (VO2max) treadmill testing and psychological stress testing (final sample N = 28). Heart rate and blood pressures were measured during performance on a computer-controlled arithmetic task after pretreatment with either naltrexone (Trexan, DuPont) or a placebo. During placebo challenges, Fit subjects, compared with Nonfit, showed lower heart rate reactivity during stress and lower mean arterial blood pressures immediately before and during recovery from stress. Naltrexone eliminated these reactivity differences by increasing heart rate reactivity and raising mean arterial blood pressure in Fit subjects. These data suggest that aerobic fitness is associated with enhanced opioidergic inhibition of circulatory stress reactivity. Opioidergic modulatory effects on stress reactivity may comprise an important mechanism in fitness-associated risk reduction for cardiovascular disease.

The effects of physical activity and exercise training on psychological stress and well-being in an adolescent population

To determine whether participating in physical activity affects psychological well-being in an adolescent population, 147 adolescents completed self-reports of exercise and psychological stress and well-being. Analysis revealed that those who reported greater physical activity also reported less stress and lower levels of depression. Adolescents who experienced a higher incidence of life events also demonstrated a strong association between stress and anxiety/depression/hostility. To investigate the effects of exercise training on psychological well-being, adolescents were assigned to either high or moderate intensity aerobic training, flexibility training or a control group. The training groups met twice per week for 25-30 min. Aerobic fitness levels, heart rate, blood pressure and self-report of stress and well-being were measured prior to and following 10 weeks of training. Post-training fitness measures confirmed the effectiveness of the high intensity aerobic exercise and between groups differences for physiological and some psychological measures were found. Subjects undergoing high intensity exercise reported significantly less stress than subjects in the remaining three groups. The relationship between stress and anxiety/depression/hostility for the high intensity group was considerably weakened at the end of the training period. For the remaining subjects, however, this relationship was, if anything, strengthened. This experiment provides evidence to suggest that in an adolescent population, high intensity aerobic exercise has positive effects on well-being.