The effect of regular exercise on cognitive functioning and personality

A Scoping Review of the Relationship between Running and Mental Health

Poor mental health contributes significantly to global morbidity. The evidence regarding physical benefits of running are well-established. However, the mental health impacts of running remain unclear. An overview of the relationship between running and mental health has not been published in the last 30 years. The purpose of this study was to review the literature on the relationship between running and mental health. Our scoping review used combinations of running terms (e.g., Run* and Jog*) and mental health terms (general and condition specific). Databases used were Ovid(Medline), Ovid(Embase), ProQuest and SportDiscus. Quantitative study types reporting on the relationships between running and mental health were included. Database searches identified 16,401 studies; 273 full-texts were analysed with 116 studies included. Overall, studies suggest that running bouts of variable lengths and intensities, and running interventions can improve mood and mental health and that the type of running can lead to differential effects. However, lack of controls and diversity in participant demographics are limitations that need to be addressed. Cross-sectional evidence shows not only a range of associations with mental health but also some associations with adverse mental health (such as exercise addiction). This review identified extensive literature on the relationship between running and mental health.

Effect of aerobic exercise on cognition in younger adults: A randomized clinical trial

OBJECTIVE

To determine efficacy of aerobic exercise for cognitive function in younger healthy adults.

METHODS

In a randomized, parallel-group, observer-masked, community-based clinical trial, 132 cognitively normal individuals aged 20-67 with below median aerobic capacity were randomly assigned to one of two 6-month, 4-times-weekly conditions: aerobic exercise and stretching/toning. Efficacy measures included aerobic capacity; cognitive function in several domains (executive function, episodic memory, processing speed, language, and attention), everyday function, body mass index (BMI), and cortical thickness.

RESULTS

Aerobic capacity increased significantly (β = 2.718; p = 0.003), and BMI decreased significantly (β = -0.596; p = 0.013) in the aerobic exercise but not in the stretching/toning condition. Executive function improved significantly in the aerobic exercise condition; this effect was moderated by age (β = 0.018 SD/y; p = 0.028). At age 40, the executive function measure increased by 0.228 SD (95% confidence interval [CI] 0.007-0.448), and by 0.596 SD (95% CI 0.219-0.973) at age 60. Cortical thickness increased significantly in the aerobic exercise group in a left frontal region and did not interact with age. Controlling for age and baseline performance, individuals with at least one APOE ε4 allele showed less improvement in executive function with aerobic exercise (β = 0.5129, 95% CI 0.0381-0.988; p = 0.0346).

CONCLUSIONS

This randomized clinical trial demonstrates the efficacy of aerobic exercise for cognition in adults age 20-67. The effect of aerobic exercise on executive function was more pronounced as age increased, suggesting that it may mitigate age-related declines. Increased cortical thickness suggests that aerobic exercise contributes to brain health in individuals as young as age 20.

CLINICALTRIALSGOV IDENTIFIER

NCT01179958.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for adults age 20-67 with below median aerobic capacity, aerobic exercise significantly improves executive function but not other measures of cognitive function.

Slowing of information processing speed without motor slowing in multiple sclerosis observed during two crossing-off tasks

INTRODUCTION

Slowing of information processing speed (IPS) is often considered one of the primary deficits seen in multiple sclerosis (MS). IPS is usually measured by tasks that involve many cognitive functions. The aim of this study was to determine whether similar IPS slowing can also be observed during two simple, timed, psychomotor crossing-off tasks.

METHOD

The Crossing-Off Test (COT), a simple psychomotor task, was performed under two conditions (COT1 corresponded to writing habits, COT2 used horizontal sweeping) in 25 relapsing-remitting MS patients (EDSS 0-1) and 25 healthy controls.

RESULTS

The MS group compared with the control group was impaired on COT1 (P=0.0043) and not on COT2 (P=0.4), and the COT1 performance of MS patients with EDSS 1 was more impaired than those of patients with EDSS 0 (P=0.008).

DISCUSSION/CONCLUSION

These results indicate that only some of the IPS cognitive subcomponents linked with COT1 tasks are initially involved in the slowing of IPS during MS, suggesting that different mechanisms are involved in each tested version of the COT.

Psychosocial benefits and implications of exercise

This review is based on a case report that concerns a young female athlete who experienced some of the negative aspects of exercise. Overtraining, a negative byproduct of excessive exercise, can turn the positive psychosocial and physiologic benefits of regular physical activity into an activity detrimental to one's health. With the proper psychological skills and appropriate exercise regimen, these negatives can be turned into positives. Once learned, the psychosocial benefits of exercise, as well as the positive implications, will become more prevalent, similar to the way in which proper physical training helps one become more fit over time.

Selectively bred rodents as models of depression and anxiety

Stress related diseases such as depression and anxiety have a high degree of co morbidity, and represent one of the greatest therapeutic challenges for the twenty-first century. The present chapter will summarize existing rodent models for research in psychiatry, mimicking depression- and anxiety-related diseases. In particular we will highlight the use of selective breeding of rodents for extremes in stress-related behavior. We will summarize major behavioral, neuroendocrine and neuronal parameters, and pharmacological interventions, assessed in great detail in two rat model systems: The Flinders Sensitive and Flinders Resistant Line rats (FSL/FRL model), and rats selectively bred for high (HAB) or low (LAB) anxiety related behavior (HAB/LAB model). Selectively bred rodents also provide an excellent tool in order to study gene and environment interactions. Although it is generally accepted that genes and environmental factors determine the etiology of mental disorders, precise information is limited: How rigid is the genetic disposition? How do genetic, prenatal and postnatal influences interact to shape adult disease? Does the genetic predisposition determine the vulnerability to prenatal and postnatal or adult stressors? In combination with modern neurobiological methods, these models are important to elucidate the etiology and pathophysiology of anxiety and affective disorders, and to assist in the development of new treatment paradigms.

Adult Hippocampal Neurogenesis: A Possible Way how Physical Exercise Counteracts Stress

It was considered that neurogenesis only occurred during the embryonic and developmental stage. This view has greatly changed since the discovery of adult neurogenesis in two brain regions: the hippocampus and the olfactory bulb. Recently, it is suggested that altered hippocampal neurogenesis is related to pathophysiology of mood disorders and mechanism of antidepressant treatments. Accumulating knowledge about the effects of physical exercise on brain function suggests a special role of adult hippocampal neurogenesis in cognitive and mental health, even though the functional significance of adult neurogenesis is still debated. The beneficial effects of running correlating with increased adult neurogenesis may provide a hint that newborn neurons may be involved, at least in part, in the counteractive mechanism of physical exercise on stress-related disorders, like depression. The present review provides an overview of recent findings to emphasize the possible involvement of hippocampal neurogenesis in mediating the beneficial effects of physical exercise on counteracting stress.

Depressive symptom outcomes of physical activity interventions: meta-analysis findings

BACKGROUND

Physical activity (PA) is consistently linked to mental health outcomes.

PURPOSE

This meta-analysis synthesized depressive symptom outcomes of supervised and unsupervised PA interventions among healthy adults.

METHODS

Comprehensive searching and coding were applied to PA interventions among adults without clinical depression. Analyses included random-effects standardized means, Q, and moderator analysis using analysis of variance and regression meta-analytic analogues.

RESULTS

Treatment versus control comparisons yielded a standardized mean effect size of 0.372 among 38 supervised PA studies and 0.522 among 22 unsupervised PA studies. Preliminary moderator analyses suggested that supervised PA interventions may be more effective when they include flexibility/resistance and low-intensity exercise. Unsupervised PA interventions may be more effective when they recommend center-based PA. Methodological moderators (random assignment, control group management) were identified.

CONCLUSIONS

These findings document that PA interventions reduce depressive symptoms even in adults without clinical depression. Moderator analyses suggest directions for future research as well as practice.

Effects of cardiorespiratory fitness and cerebral blood flow on cognitive outcomes in older women

The mechanisms by which aerobic fitness confers beneficial effects on cognition with aging are unclear but may involve cerebrovascular adaptations. In a cross-sectional study of women from the community (n=42; age range=50-90 years), we sought to determine whether physical fitness is associated with higher cerebrovascular function, and its relationship to cognition. Main outcome measures included resting cerebral blood flow, cerebrovascular reserve, physical fitness (i.e., VO₂max) and cognition. Physically fit women had lower resting mean arterial pressure (MAP) and higher cerebrovascular conductance (CVC) than sedentary women. Overall cognition was negatively correlated with age and positively correlated with VO₂max. VO₂max was a predictor of resting CVC and MAP, and CVC and MAP when end-tidal gases were held constant at near-resting values. MAP and CVC were predictors of cognition. This study identified strong associations between physical fitness, vascular function and cognition, and provides new understanding regarding the mechanisms by which fitness positively impacts cognition with aging. The implications of this research are considerable and warrant future investigation.

Short-term exercise in aged Tg2576 mice alters neuroinflammation and improves cognition

Exercise is a treatment paradigm that can ameliorate cognitive dysfunction in Alzheimer disease (AD) and AD mouse models. Since exercise is also known to alter the peripheral immune response, one potential mechanism for the cognitive improvement following exercise may be by modulating the inflammatory repertoire in the central nervous system. We investigated the effects of voluntary exercise in the Tg2576 mouse model of AD at a time-point at which pathology has already developed. Inflammatory mRNA markers are increased in sedentary Tg2576 mice versus non-transgenic controls. We demonstrate that short-term voluntary wheel running improved spatial learning in aged transgenic mice as compared to sedentary Tg2576 controls. Inflammatory profiles of the Tg2576 and non-transgenic mice were different following exercise with the non-transgenic mice showing a broader response as compared to the Tg2576. Notably, exercising Tg2576 exhibited increases in a few markers including CXCL1 and CXCL12, two chemokines that may affect cognition.

Alterations in spatial learning and memory after forced exercise

Exercise has been shown to influence learning and memory. Most studies were performed with a voluntary running paradigm (e.g. running wheel) in mice. However, such effects of exercise on learning and memory are less well demonstrated using a forced running paradigm (e.g. treadmill). The present study was designed to examine the effects of 12 weeks of forced treadmill running on learning and memory performance in rats. We have previously shown that forced running resulted in qualitative and quantitative changes in the cholinergic neurons of the horizontal diagonal band of Broca (HDB) in the septum. This study was conducted in order to determine whether or not these changes occur simultaneously with enhanced learning and memory. The one-day version of the Morris water maze (MWM) test [Frick, K.M., Stillner, E.T., Berger-Sweeney, J., 2000. Mice are not little rats: species differences in a one-day water maze task. NeuroReport 11, 3461-3465] was used to test spatial learning and memory after the exercise period. Our data showed that runners displayed better spatial learning and memory when compared to nonrunners. This was evidently shown by a reduction in the time required for spatial acquisition (p<0.05) and superior probe trial performance (p<0.05). A shorter distance swam by the runners also suggested improved learning over the nonrunners (p<0.05). In an attempt to revalidate our earlier quantitative results, we used design-based stereology (DBS) to estimate the number of cholinergic neuronal profile population in the medial septum and diagonal band (MSDB). We confirmed that forced running increased the cholinergic neuronal profile subpopulation in the HDB (Coefficient of Error<0.2). Taken together, these results indicate that forced exercise could influence learning and memory with a concomitant increase in the number of cholinergic neurons in the HDB.

The effect of exercise on hippocampal integrity: review of recent research

OBJECTIVES

To review salient basic research regarding physical exercise as a major protective factor against hippocampal degradation and to emphasize its relevance to humans.

METHOD

Recent mammalian and human research literature search and theoretical discussion.

RESULTS

The cascade of cellular damages from oxidative stress, nitrosative stress and gluco-corticoid effects are cumulative and age related. Exercise training reduces oxidative stress, nitro-sative stress and improves neuroendocrine autoregulation which counteracts damages from stress- and age-related neuronal degeneration, brain ischemia and traumatic brain injury. Conversely, lack of exercise and motility restrictions are associated with increased vulnerability from oxidative stress, nitrosative stress and glucocorticoid excesses, all of which precede amyloid deposition and are fundamental in the cascade of events resulting in neuronal degradation, especially in the hippocampi.

CONCLUSIONS

Despite the paucity of human research, basic animal models and clinical data overwhelmingly support the notion that exercise treatment is a major protective factor against neurodegeneration of varied etiologies. The final common pathway of degradation is clearly related to oxidative stress, nitrosative stress, glucocorticoid dysregulation, inflammation and amyloid deposition. We conclude that people prone to chronic distress, brain ischemia, brain trauma, and the aged are at increased risk for neurodegenerative diseases such as Alzheimer's. Exercise training may be a major protective factor but without clinical guidelines, its prescription and success with treatment adherence remain elusive.

Exercise increases the vulnerability of rat hippocampal neurons to kainate lesion

Available evidence suggests that regular, moderate-intensity exercise has beneficial effects on neural health, perhaps including neuroprotection. To evaluate this idea further, we compared the severity of kainate-induced neuronal loss in exercised versus sedentary female rats. Stereological estimations of neuron number revealed that rats in the exercise condition exhibited significantly greater neuron loss in hippocampal region CA2/3, suggesting that high levels of physical activity may increase neuronal vulnerability to excitotoxicity.

Physical activity elicits sustained activation of the cyclic AMP response element-binding protein and mitogen-activated protein kinase in the rat hippocampus

To elucidate molecular mechanisms involved in physical activity-induced beneficial effects on brain function, we studied in rats the influence of voluntary running on the activation in the hippocampus of cyclic AMP response element-binding protein (CREB) and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinase (ERK). These are signaling molecules that play critical roles in synaptic plasticity, including learning and memory. Exercise resulted in an increase in the level of the activated transcription factor, CREB phosphorylated at Ser-133. The amount of the activated transcription factor about doubled already after 1 night of running and remained elevated for at least a week, although control levels were restored after 1 month of exercise. In addition, binding activity in nuclear extracts to cyclic AMP response element (CRE) motif containing oligonucleotides increased significantly in the hippocampus after 3 nights of exercise, although the total amount of the immunochemically identified CREB remained unaltered. Electrophoretic mobility supershift assays indicated that the increased binding was due to the recruitment of members of this transcription factor family, in addition to the CREB proper. Voluntary running also resulted in an increase in the level of phosphorylated MAPK (both p42 and p44). The time-courses of the increases in the level of the phosphorylated protein kinase and the activated transcription factor were different. In comparison with the activated CREB, the increase in the phosphorylated MAPK was delayed, but lasted longer, being detectable even after 1 month of exercise. These observations are consistent with the view that the relatively long-lasting activation of these signaling molecules participates in the regulation of genes, such as the neurotrophin genes, and contributes to the beneficial effects of physical exercise on brain function.

Effects of exercise on gene-expression profile in the rat hippocampus

Exercise has beneficial effects on brain function, including the promotion of plasticity and the enhancement of learning and memory performance. Previously we found that exercise increases the expression of certain neurotrophic factors including brain derived neurotrophic factor in the rat hippocampus. To further explore the molecular mechanisms underlying these changes, we used high-density oligonucleotide microarrays containing probe sets representing approximately 5000 genes to analyze the level of gene transcripts in the hippocampus of rats voluntary running for 3 weeks in comparison with sedentary animals. An improved statistical approach for the analysis of DNA microarray data, Cyber-T, was utilized in data analysis. Here we show that exercise leads to changes in the level of a large number of gene transcripts, many of which are known to be associated with neuronal activity, synaptic structure, and neuronal plasticity. Our data indicate that exercise elicits a differential gene expression pattern with significant changes in genes of relevance for brain function.

Estrogen and exercise interact to regulate brain-derived neurotrophic factor mRNA and protein expression in the hippocampus

We investigated the possibility that estrogen and exercise interact in the hippocampus and regulate brain-derived neurotrophic factor (BDNF), a molecule increasingly recognized for its role in plasticity and neuron function. An important aspect of this study is to examine the effect of different time intervals between estrogen loss and estrogen replacement intervention. We demonstrate that in the intact female rat, physical activity increases hippocampal BDNF mRNA and protein levels. However, the exercise effect on BDNF up-regulation is reduced in the absence of estrogen, in a time-dependent manner. In addition, voluntary activity itself is stimulated by the presence of estrogen. In exercising animals, estrogen deprivation reduced voluntary activity levels, while estrogen replacement restored activity to normal levels. In sedentary animals, estrogen deprivation (ovariectomy) decreased baseline BDNF mRNA and protein, which were restored by estrogen replacement. Despite reduced activity levels in the ovariectomized condition, exercise increased BDNF mRNA levels in the hippocampus after short-term (3 weeks) estrogen deprivation. However, long-term estrogen-deprivation blunted the exercise effect. After 7 weeks of estrogen deprivation, exercise alone no longer affected either BDNF mRNA or protein levels. However, exercise in combination with long-term estrogen replacement increased BDNF protein above the effects of estrogen replacement alone. Interestingly, protein levels across all conditions correlated most closely with mRNA levels in the dentate gyrus, suggesting that expression of mRNA in this hippocampal region may be the major contributor to the hippocampal BDNF protein pool. The interaction of estrogen, physical activity and hippocampal BDNF is likely to be an important issue for maintenance of brain health, plasticity and general well-being, particularly in women.

Diverse effects of prolonged physical training on learning of the delayed non-matching to sample by rats

The physiological effects of physical exercise have been extensively studied. Nevertheless, its influence on cognitive functioning remains a matter of controversy. In this study we have attempted to assess the effects of repeated exercise (6 weeks of daily treadmill running, meant to resemble human physical training), on parallel learning of a complex task [delayed non matching to sample (DNMS)] by rats. The trained rats appeared to learn the procedure slower and made a significantly lower percentage of correct choices (P<0.01) as compared to those in the non-trained control group. However, when only those rats, from both the groups, which reached the criterion of 80% correct choices in two consecutive sessions were compared, no significant differences were observed. These results suggest an adverse influence of long term physical exercise on rats' ability to learn complex tasks, but only by the 'poor performers'. The 'good performers' were insensitive to the deleterious effects of the exercise.

Spatial learning and physical activity contribute to the induction of fibroblast growth factor: neural substrates for increased cognition associated with exercise

New evidence indicates that neural activity regulates the expression of trophic factors in the brain but regulation of these molecules by select aspects of behaviour remains solely a fascinating possibility. We report that following training in the Morris water maze, a spatial memory task, the hippocampus and cerebellum of learning rats exhibited an increase in basic fibroblast growth factor messenger RNA. Basic fibroblast growth factor messenger RNA levels were higher during the learning of the task and decreased once asymptotic performance was reached, suggesting an involvement of basic fibroblast growth factor in learning/memory. An active control group, which exercised for the same time as the learning group but the spatial learning component of the task was minimized, exhibited a minor increase in basic fibroblast growth factor messenger RNA. The intensification of the physical activity component of the task by massed or intensive training resulted in greater increases in basic fibroblast growth factor messenger RNA for both learning and yoked groups, but levels of basic fibroblast growth factor messenger RNA in the learning group remained higher than yoked only in the cerebellum. Changes in basic fibroblast growth factor were accompanied by an increase in astrocyte density in the hippocampus in agreement with described roles of basic fibroblast growth factor in astrocyte proliferation/reactivity. Results suggest that learning potentiates the effects of physical activity on trophic factor induction in select brain regions. Trophic factor involvement in behaviour may provide a molecular basis for the enhanced cognitive function associated with active lifestyles, and guide development of strategies to improve rehabilitation and successful ageing.

Physical exercise induces FGF-2 and its mRNA in the hippocampus

Clinical and experimental evidence indicate that physical activity has a positive impact on brain function; however, the molecular bases for how exercise affects the structure and function of the brain are largely unknown. We have investigated the influences of variable periods of voluntary wheel-running on the expression of basic fibroblast growth factor and its mRNA in various brain regions. Nuclease protection assays revealed that the hippocampus was the only region examined exhibiting changes in FGF-2 mRNA as a result of exercise. FGF-2 mRNA increased to reach a peak by the 4th night of wheel-running. FGF-2 immunoreactivity, normally located in the perinuclear area of astrocytes, following exercise became stronger and appeared to spread to the cytoplasm and processes of astrocytes. Quantification of the FGF-2-immunoreactive astrocytes showed an increase in density between 2 and 4 nights of running in discrete regions of the hippocampus. These results demonstrate that exercise regulates FGF-2 expression and suggest that growth factors are likely mediators of the positive effects of exercise on the brain.

Aerobic exercise, subjective health and psychological well-being within age and gender subgroups

This research examines relationships between different forms of aerobic exercise (swim, walk, jog, dance) and two measures of health: subjective health and psychological well-being. We hypothesize that the relationship between aerobic exercise and subjective health/well-being will be notably stronger for older than younger persons and females than males. This prediction is based on Homans' exchange theory of investments and rewards. Since social norms concerning aerobic exercise are likely to be weaker among older (than younger) persons and among women than men, older persons and women who do exercise are making special investments and should expect greater rewards (good health). The concept of 'exercise norms' implies social comparisons with others. Accordingly, age comparative data were analyzed to see if older persons who exercise see themselves as more active than their age peers than do younger persons. Data come from a national probability sample of 3025 adults (National Survey of Personal Health Practices and Consequences). As predicted, exercise was much more strongly related to subjective health and well-being among older than younger respondents. In the main, the gender hypothesis was not supported.

Physical conditioning in rats influences the central and peripheral catecholamine responses to sustained exercise

We have investigated the effect of treadmill running in rats (25m.min-1 using a 3% gradient; for 1 h or 2 h) on the cortical extracellular concentrations of noradrenaline (NA) and its main metabolites-3,4-dihydroxyphenylglycol and 3-methoxy-4-hydroxyphenylglycol- and the plasma adrenaline (A) and NA concentrations in relation to prior physical conditioning (1 or 2-h running.day-1 for 12 days). Cortical microdialysates and peripheral blood were collected during 1-h resting, 1-h or 2-h running and for 1 h after exercise. Catecholamines and their metabolites were quantitated using high performance liquid chromatography with electrochemical detection. Treadmill running stimulated concomitantly peripheral catecholamine secretion and central noradrenergic activity, i.e. NA turnover and release. The effect extended into the recovery period even more as the duration of the run increased. Prior physical conditioning greatly influenced the central and peripheral catecholamine responses: the 1-h trained rats experienced the 2-h run as a stressful new event eliciting great long-lasting catecholamine responses, whereas the 2-h trained rats exhibited a progressive sustained catecholamine increase with an earlier onset of the central NA release. The data are discussed in relation to the psychological and intellectual effects of exercise and physical fitness in humans. In addition, the positive correlation found between the central noradrenergic activation and peripheral A secretion confirmed and extended our previous observations in exercising men and gave support to the hypothesis that the elevation of circulating A can be a relevant factor mediating--directly or indirectly--the exercise-induced central effects.

Vigorous, aerobic exercise versus general motor training activities: effects on maladaptive and stereotypic behaviors of adults with both autism and mental retardation

Examined the effects of antecedent exercise conditions on maladaptive and stereotypic behaviors in 6 adults with both autism and moderate to profound mental retardation. The behaviors were observed in a controlled environment before and after 2 exercise and 1 non-exercise conditions. From the original group of 6 participants, 2 were selected subsequently to participate in aerobic exercise immediately before performing a community-integrated vocational task. Only antecedent aerobic exercise significantly reduced maladaptive and stereotypic behaviors in the controlled setting. Neither of the less vigorous antecedent conditions did. When aerobic exercise preceded the vocational task, similar reductions were observed. There were individual differences in response to antecedent exercise. Use of antecedent aerobic exercise to reduce maladaptive and stereotypic behaviors of adults with both autism and mental retardation is supported.

The effect of exercise on depression, anxiety and other mood states: a review

This paper addresses the current literature related to investigations of the link between exercise treatments and depression, anxiety and other mood states. Results from these investigations are supportive of the anti-depressant, anti-anxiety and mood enhancing effects of exercise programs. There were considered to be, however, a number of potential methodological problems in many of the research studies; the nature of these were considered. Finally, some possible directions for future research are outlined.

The effects of aerobic exercise on psychological and behavioral variables of individuals with developmental disabilities: a critical review

Physical fitness of persons who are developmentally disabled has received relatively little attention in the special education literature when compared to intellectual functioning (e.g., learning, memory, and language) and to acquisition of functional skills (e.g., self-care, community, and vocational). Despite an increased interest in recreational programming stimulated by the concept of functional curricula, teachers may still be reluctant to include physical fitness activities in their students' schedules. Perhaps physical fitness programming for those with developmental disabilities would have wider appeal and application if it were embedded in the broader context of psychological and behavioral change (i.e., engagement in exercise produces generalized changes beyond direct improvement in physical well-being). This article is a review and critique of literature that focuses on the effects of participation in aerobic exercise on three classes of psychological/behavioral variables for persons with mental retardation and associated disabilities. The methodology that characterizes this literature is analyzed, and recommendations for future research are proposed.

Effects of physical conditioning on information-processing efficiency

This study investigated changes in information-processing efficiency that occur when physical fitness improves. Information-processing variables were Sternberg's memory-scan rate, Posner's name-access time, the Cattell Culture Fair Intelligence Test, and numbers of words remembered from word lists. At present and posttest 10 to 12 wk. later, 66 adults between the ages of 18 and 48 yr. took all cognitive tests and rode a bicycle ergometer to estimate physical fitness. A 2 X 2 (improved/stable fitness groups by pretest/posttest trials) analysis of variance with repeated measures indicated that the group who improved 15% or more in physical fitness improved significantly more on the name-access time than the group whose fitness remained stable. There was a trend toward improvement in memory-scan rate and number of words remembered on the first word trial by people who became more fit. The results may have implications for assessment and training of personnel in occupations where speeded perception and responses are required.

Running and depression

Two studies on the relationship between running and depression among normal persons are reported. Study 1 investigated whether a group of 21 runners were significantly less depressed, as measured by the Beck Depression Inventory, than a group of 21 nonexercisers who were matched on sex, age, and height/weight ratio. The runners were significantly less depressed than the nonexercisers. Study 2 assessed whether cardiovascular fitness correlated with depression. Using scores on the Beck Depression Inventory as the criterion of depression, 17 depressed subjects and 17 nondepressed subjects took the Harvard "Step Test", the measure of cardiovascular fitness. There was a significant negative r of -.30. It is noted that the basis of the relation between running and depression is still unclear and suggestions for research are presented.

Recent advances in the treatment of low back pain

There is at the present time an epidemic of low back pain in the industrialized countries. Although the exact origin of such pain is still unknown, there is increasing awareness that the outcome is usually favourable. Only some 10% of those suffering an acute episode of back pain are incapacitated for more than 6 weeks. The causes of long standing back pain are being identified in an increasing number of patients. They include anatomical and pathological disturbances in the motion segment as well as psychological, social and political causes. There are numerous factors which influence the pathophysiology of the motion segment. The degree of loading has been successfully measured and delineated for various postures and exercises, including those at work. The nutritional pathways to the disc have been established and the effect of various external factors measured. Movement is good for the disc and the importance of continuous passive motion for the healing of diseased or injured connective tissues is not established. Activation of large muscle groups increases the production of the body's pain reducing encephalins. Early diagnosis and early mobilisation of the patient should be of benefit, and long term bed rest and inactivity must be prevented. Fewer cases will need operation in the future. Improved imaging techniques and better methods of operation and fixation will help those few who have a definite pathological lesion amenable to surgery.

Medical psychology in exercise and sport

Several psychological outcomes that accompany acute and chronic exercise have medical significance. Transient reductions in somatic tension and subjective anxiety appear most reliable. Symptom abatement in moderate depression can occur with chronic exercise in a manner comparable to psychotherapy and may offer a better prognosis in some instances. Other cognitive, behavioral, and perceptual events associated with exercise may assist in managing mental health, and exercise has been successfully used as a therapeutic adjunct in a variety of psychiatric disorders. Regular exercise may also complement treatments designed to manage aspects of coronary-prone behavior and psychoendocrine responsivity to mental stress. The lack of strict experimental control or effective placebo contrasts in most exercise studies precludes a convincing argument that exercise causes the psychological outcomes observed. Rather, expectancy of benefits, generalized treatment or attention effects, social reinforcement, and past history or selection bias represent likely alternatives. These competing explanations do not discount, however, that many individuals benefit in a clinically significant way. Exercise offers a low-cost alternative or adjunct with side effects that appear largely health-related. Although the effective psychological dosage or modality has not been quantified, current physiologic guidelines of the American College of Sports Medicine (large muscle rhythmic activity, for 20 to 60 minutes, 3 to 5 days per week at 60 to 80 per cent age-adjusted maximal heart rate), or a weekly caloric cost of 2000 kcal, should be effective with little medical risk. However, no evidence confirms that an increase in metabolic or psychoendocrine tolerance to exercise is necessary or sufficient for psychological outcomes to occur. Although biologic adaptations are known to follow exercise training and subside with diminished activity, there is currently no objective evidence that habitual exercise leads to dependence. If exercise has use in managing subjective or somatic symptoms, these may return during periods of exercise abstinence. Moreover, despite popular hypotheses concerning endorphins and biogenic amines, no direct relationships have yet been shown between exercise-induced mood swings and peripheral biochemical events. A proportion of habitual runners have reported acute episodes of euphoria-like states during or following exercise, but this remains a subjective and unpredictable event that may be related to psychophysiologic relaxation or acute changes in self-esteem.(ABSTRACT TRUNCATED AT 400 WORDS)