Psychological consequences of exercise deprivation in habitual exercisers

Cognitive Vulnerability to Mood Deterioration in an Exercise Cessation Paradigm

Mood deterioration in response to exercise cessation is well-documented, but moderators of this effect remain unknown. This study tested the hypothesis that physically active individuals with higher levels of cognitive vulnerability (i.e., tendencies towards negative thought content and processes in response to stress or negative mood states) are at greater risk for increased anxiety and depressive symptoms when undergoing exercise cessation. Community adults meeting recommended physical activity guidelines (N=36) participated in a 4-week prospective, longitudinal study with 2 weeks each of maintained exercise and exercise cessation. Cognitive vulnerability measures included dysfunctional attitudes, brooding rumination, and cognitive reactivity (i.e., change in dysfunctional attitudes over a dysphoric mood induction). Anxiety and depression symptoms increased during exercise cessation. Brooding emerged as a risk factor for increases in Tension scores on the Profile of Mood States-Brief during exercise cessation. Future studies should explore brooding as a mediator (i.e., potential mechanism) of exercise-induced mood deterioration.

Humans have a basic physical and psychological need to move the body: Physical activity as a primary drive

Physical activity, while less necessary for survival in modern times, is still essential for thriving in life, and low levels of movement are related to numerous physical and mental health problems. However, we poorly understand why people move on a day-to-day basis and how to promote greater energy expenditure. Recently, there has been a turn to understand automatic processes with close examination of older theories of behavior. This has co-occurred with new developments in the study of non-exercise activity thermogenesis (NEAT). In this narrative review, it is hypothesized that psycho-physiological drive is important to understand movement in general and NEAT, specifically. Drive, in short, is a motivation state, characterized by arousal and felt tension, energizing the organism to acquire a basic need. Movement is a biological necessity, like food, water, and sleep, but varies across the lifespan and having the greatest impact before adolescence. Movement meets various criteria for a primary drive: (a) deprivation of it produces feelings of tension, such as an urge or craving, known as affectively-charged motivation states, and particularly the feelings of being antsy, restless, hyper or cooped up, (b) provision of the need quickly reduces tension - one can be satiated, and may even over-consume, (c) it can be provoked by qualities of the environment, (d) it is under homeostatic control, (e) there is an appetite (i.e., appetence) for movement but also aversion, and (f) it has a developmental time course. Evidence for drive has mainly come from children and populations with hyperkinetic disorders, such as those with anorexia nervosa, restless legs syndrome, and akathisia. It is also stimulated in conditions of deprivation, such as bed rest, quarantine, long flights, and physical restraint. It seems to be lacking in the hypokinetic disorders, such as depression and Parkinson's. Thus, drive is associated with displeasure and negative reinforcement, subsuming it within the theory of hedonic drive, but it may fit better within new paradigms, such as the WANT model (Wants and Aversions for Neuromuscular Tasks). Recently developed measurement tools, such as the CRAVE scale, may permit the earnest investigation of movement drive, satiation, and motivation states in humans.

Understanding exercise addiction, psychiatric characteristics and use of anabolic androgenic steroids among recreational athletes – An online survey study

Background

The purpose of this paper was to explore maladaptive behaviors among physically active individuals, including exercise dependence and use of anabolic steroids. Both exercise addiction (EA) and use of anabolic androgenic steroids (AAS) correlate to high amounts of exercise and EA have been linked to eating disorders and other mental health problems.

Methods

An internet survey was spread through fitness-related social media. Inclusion criteria were age ≥ 15 years and exercise frequency ≥ thrice weekly. Exercise addiction inventory identified those at-risk of EA (rEA). Characteristics of rEA were compared to those not at risk. In a separate analysis, AAS users were compared to AAS-naïve individuals.

Results

In total, 3,029 participants completed the questionnaire. Of these, 11% screened positive for being rEA, and 23% for ED. Factors associated with EA included daily exercise, social phobia, eating disorders and OCD. Risk consumption of alcohol was a negative predictor. Thirty seven participants had taken AAS the last year. These were mainly men, bodybuilders/powerlifters and more often used amphetamines and opioids.

Discussion

This exploratory study supports EA being strongly associated with eating disorders. Identified associations between EA and compulsive or anxiety disorders warrant further research to clarify if these associations arise prior to, together with, or secondary to EA.

Can listening-related fatigue influence well-being? Examining associations between hearing loss, fatigue, activity levels and well-being

Objective

Well-being is influenced by the activities we undertake. Hearing loss may reduce well-being directly through increased listening-related fatigue due to cognitive and emotional strain in challenging situations. Hearing loss and hearing device use may also indirectly impact fatigue and well-being by altering the frequency and type of daily-life activities. This review examines the available literature to help understand the relationships.

Design

We provide (i) a summary of the extant literature regarding hearing loss, hearing device use and fatigue in adults, as well as regarding fatigue and daily-life activity (work, social and physical) and (ii) a systematic search and narrative review of the relationships between hearing loss, hearing device use and activity.

Study sample

The systematic search resulted in 66 eligible texts.

Results

Data examining well-being in persons with hearing loss are limited. Our literature review suggests that well-being can be related directly and indirectly to hearing loss, hearing device use, activity level and listening-related fatigue.

Conclusions

Variations and interactions between hearing loss, hearing device use, fatigue and activity levels can be expected to impact well-being in persons with hearing loss in direct and indirect ways. Future research linking hearing and daily-life fatigue should take account of activity levels.

Motivation States for Physical Activity and Sedentary Behavior: Desire, Urge, Wanting, and Craving

To better explain daily fluctuations in physical activity and sedentary behavior, investigations of motivation are turning from social cognitive frameworks to those centered on affect, emotion and automaticity, such as the Affect and Health Behavior Framework (AHBF), Integrated Framework and Affective-Reflective Theory (ART). This shift has necessitated: (a) re-examination of older theories and their constructs, such as drives, needs and tensions and (b) an inspection of competing theories from other fields that also attempt to explain dynamic changes in health behaviors. The Dynamical Model of Desire, Elaborated Intrusion Theory and others commonly share with AHBF the idea that human behavior is driven strongly by desires and/or the similar concepts of wants, urges, and cravings. These affectively-charged motivation states (ACMS) change quickly and may better explain physical activity behavior from one moment to the next. Desires for movement predominantly derive from negative but also positive reinforcement. Data from clinical populations with movement dysfunction or psychiatric disorders provides further evidence of these drivers of movement. Those with Restless Legs Syndrome, akathisia, tic disorders and exercise dependence all report strong urges to move and relief when it is accomplished. Motor control research has identified centers of the brain responsible for wants and urges for muscular movement. Models elaborated herein differentiate between wants, desires, urges and cravings. The WANT model (Wants and Aversions for Neuromuscular Tasks) conceptualizes desires for movement and rest as varying by magnitude, approach or avoidance-orientation (wants versus aversions) and as occupying independent dimensions instead of opposite ends of the same axis. For instance, one hypothetically might be in a state of both high desire for movement and rest simultaneously. Variations in motivation states to move and rest may also be associated with various stress states, like freezing or fight and flight. The first validated instrument to measure feelings of desire/want for movement and rest, the CRAVE Scale (Cravings for Rest and Volitional Energy Expenditure) is already shedding light on the nature of these states. With these advances in theory, conceptual modeling and instrumentation, future investigations may explore the effects of desires and urges for movement and sedentary behavior in earnest.

Spontaneous appetence for wheel-running: a model of dependency on physical activity in rat

According to human observations of a syndrome of physical activity dependence and its consequences, we tried to examine if running activity in a free activity paradigm, where rats had a free access to activity wheel, may present a valuable animal model for physical activity dependence and most generally to behavioral dependence. The pertinence of reactivity to novelty, a well-known pharmacological dependence predictor was also tested. Given the close linkage observed in human between physical activity and drugs use and abuse, the influence of free activity in activity wheels on reactivity to amphetamine injection and reactivity to novelty were also assessed. It appeared that (1) free access to wheel may be used as a valuable model for physical activity addiction, (2) two populations differing in activity amount also differed in dependence to wheel-running. (3) Reactivity to novelty did not appeared as a predictive factor for physical activity dependence (4) activity modified novelty reactivity and (5) subjects who exhibited a high appetence to wheel-running, presented a strong reactivity to amphetamine. These results propose a model of dependency on physical activity without any pharmacological intervention, and demonstrate the existence of individual differences in the development of this addiction. In addition, these data highlight the development of a likely vulnerability to pharmacological addiction after intense and sustained physical activity, as also described in man. This model could therefore prove pertinent for studying behavioral dependencies and the underlying neurobiological mechanisms. These results may influence the way psychiatrists view behavioral dependencies and phenomena such as doping in sport or addiction to sport itself.

"N-of-1"-Study: A concept of acute and chronic stress research using the example of ballroom dancing

Athletes often report on heightened stress, higher disease susceptibility, and a deterioration in mood and performance throughout periods of high training load and competitions. This paper presents a single-case study combining different research approaches to monitor the dynamic, idiosyncratic responses to competitive stress in elite sports using the example of professional ballroom dancing. Throughout an 8-month period (313 data points), one international-level female dancer provided data on mood, stress, and fatigue. In parallel, she collected saliva samples for the assessment of cortisol (sCort) and alpha-amylase (sAA). A hair strand was collected every 3 months to examine cumulative cortisol secretion. As expected, perceived stress was related to a reduction in well-being. On a daily basis, sCort predicted lower fatigue. In addition, tournaments resulted in a 3-fold and a 2-fold increase in sCort and sAA, respectively, and there was a pronounced drop in hair cortisol in the aftermath of a surgery-related break from dancing. We confirm competitive ballroom dancing to constitute a major stressor with immediate and prolonged consequences for self-reported well-being and biological stress markers. Single-case studies offer much potential for the observation of complex dynamic associations. In a next step, this approach will also become relevant when evaluating the efficacy of preventive and therapeutic interventions on an individual level.

Does ceasing exercise induce depressive symptoms? A systematic review of experimental trials including immunological and neurogenic markers

BACKGROUND

Regular exercise in adults improves depressive symptoms (DS) and major depressive disorder (MDD), however the clinical effects of ceasing exercise are largely unknown.

METHODS

Seven databases were searched from inception to December 2017. Eligibility criteria included English language studies investigating the effects of ceasing exercise on DS or MDD in regularly active adults with or without prior DS or MDD. Blood based markers related to exercise cessation (EC) were assessed, if recorded. Studies investigating exercise follow-up periods were excluded.

RESULTS

No studies investigated EC in MDD. Six studies including two RCTS and three studies investigating neurogenic and immune biological markers associated with DS met inclusion criteria (152 healthy adults, females n = 50/32.89%). Compared to baseline, EC increased DS after three days, one week, and two weeks. Female participants had significantly more DS than male participants. Following EC, no changes in brain derived neurotrophic factor (BDNF) or tumour necrosis factor alpha (TNF) were evident, however C-reactive protein (CRP) at week one and interleukin 6 (IL6) at week two were reduced.

LIMITATIONS

Quality concerns including risks of attrition and reporting bias limit our confidence in these results.

CONCLUSIONS

Ceasing regular exercise increases DS in healthy adults, with greater DS in females than males. Contrary to the cytokine/inflammatory hypothesis of depression, DS were associated with reduced CRP and IL6 and without increased TNF. High quality trials are needed to extend this field of research in both healthy and MDD populations.

Perceived fatigue and energy are independent unipolar states: Supporting evidence

Persistent fatigue is a common problem (∼20-45% of U.S. population), with higher prevalence and severity in people with medical conditions such as cancer, depression, fibromyalgia, heart failure, sleep apnea and multiple sclerosis. There are few FDA-approved treatments for fatigue and great disagreement on how to measure fatigue, with over 250 instruments used in research. Many instruments define fatigue as "a lack of energy", thus viewing energy and fatigue states as opposites on a single bipolar continuum. In this paper, we hypothesize that energy and fatigue are distinct perceptual states, should be measured using separate unipolar scales, have different mechanisms, and deficits should be treated using tailored therapies. Energy and fatigue independence has been found in both exploratory and confirmatory factor analysis studies. Experiments in various fields, including behavioral pharmacology and exercise science, often find changes in energy and not fatigue, or vice versa. If the hypothesis that energy and fatigue are independent is correct, there are likely different mechanisms that drive energy and fatigue changes. Energy could be increased by elevated dopamine and norepinephrine transmission and binding. Fatigue could be increased by elevated brain serotonin and inflammatory cytokines and reduced histamine binding. The hypothesis could be tested by an experiment that attempts to produce simultaneously high ratings of energy and fatigue (such as with two drugs using a randomized, double-blind, placebo-controlled design), which would offer strong evidence against the common viewpoint of a bipolar continuum. If the hypothesis is correct, prior literature using bipolar instruments will be limited, and research on the prevalence, mechanisms, and treatment of low energy and elevated fatigue as separate conditions will be needed. In the immediate future, measuring both energy and fatigue using unipolar measurement tools may improve our understanding of these states and improve therapeutic outcomes.

Mental health consequences of exercise withdrawal: A systematic review

OBJECTIVE

A sedentary lifestyle has been associated with mental health disorders. Many medical conditions result in the cessation of exercise, which may increase the risk of developing mental health problems. The purpose of this article is to systematically review the literature examining the effects of exercise withdrawal on mental health.

METHOD

Literature was searched using PubMed, PsycINFO, and SPORTdiscus for studies that experimentally manipulated the withdrawal of exercise and included mental health as outcome measure.

RESULTS

A total of 19 studies met inclusion criteria (total N=689 with 385 individuals participating in an exercise withdrawal condition). Exercise withdrawal consistently resulted in increases in depressive symptoms and anxiety. Other mental health outcomes were investigated infrequently. Severe mental health issues requiring clinical intervention after experimentally controlled exercise withdrawal was rare. Heterogeneity in methods and outcomes was observed, especially in terms of the duration of exercise withdrawal (range 1 to 42days, median=7days), with stronger effects if exercise withdrawal exceeded 2weeks.

CONCLUSION

Experimentally controlled exercise withdrawal has adverse consequences for mental health. These observations in healthy individuals may help to understand the onset of mental health problems in response to acute and chronic medical conditions associated with reduced physical activity. Future research is needed to investigate potential mechanisms explaining the adverse mental health consequences of cessation of exercise that will provide new targets for clinical interventions.

Effect of Acute Exercise on Fatigue in People with ME/CFS/SEID: A Meta-analysis

PURPOSE

A prominent symptom of myalgic encephalomyelitis, chronic fatigue syndrome, or systemic exertion intolerance disease (ME/CFS/SEID) is persistent fatigue that is worsened by physical exertion. Here the population effect of a single bout of exercise on fatigue symptoms in people with ME/CFS/SEID was estimated and effect moderators were identified.

METHODS

Google Scholar was systematically searched for peer-reviewed articles published between February 1991 and May 2015. Studies were included where people diagnosed with ME/CFS/SEID and matched control participants completed a single bout of exercise and fatigue self-reports were obtained before and after exercise. Fatigue means, standard deviations, and sample sizes were extracted to calculate effect sizes and the 95% confidence interval. Effects were pooled using a random-effects model and corrected for small sample bias to generate mean Δ. Multilevel regression modeling adjusted for nesting of effects within studies. Moderators identified a priori were diagnostic criteria, fibromyalgia comorbidity, exercise factors (intensity, duration, and type), and measurement factors.

RESULTS

Seven studies examining 159 people with ME/CFS/SEID met inclusion criteria, and 47 fatigue effects were derived. The mean fatigue effect was Δ = 0.73 (95% confidence interval = 0.24-1.23). Fatigue increases were larger for people with ME/CFS/SEID when fatigue was measured 4 h or more after exercise ended rather than during or immediately after exercise ceased.

CONCLUSIONS

This preliminary evidence indicates that acute exercise increases fatigue in people with ME/CFS/SEID more than that in control groups, but effects were heterogeneous between studies. Future studies with no-exercise control groups of people with ME/CFS/SEID are needed to obtain a more precise estimate of the effect of exercise on fatigue in this population.

Active and sedentary behaviors influence feelings of energy and fatigue in women

PURPOSE

The purpose of this study was to determine whether physical activity and sedentary behaviors interact to influence feelings of energy and fatigue in women.

METHODS

Feelings of energy and fatigue and physical activity and sedentary behaviors were assessed in 73 women (mean ± SD age = 37 ± 10) who were dichotomized based on physical activity status (meets physical activity recommendations [n = 40] vs insufficiently active [n = 33]) and the amount of uninterrupted sedentary time they accumulated (high [n = 38] vs low [n = 35]). Three 2 × 2 ANOVA were conducted to determine the relationships between physical activity and sedentary behaviors and between energy (vigor and vitality) and fatigue.

RESULTS

Results demonstrated a significant main effect for meeting physical activity recommendations for both vigor (P = 0.004) and vitality (P < 0.001). For fatigue, there was a significant interaction between physical activity and sedentary behaviors (P = 0.005). Analyses of simple main effects demonstrated that in women who were not meeting physical activity recommendations, those who were less sedentary had significantly lower levels of fatigue than their more sedentary peers (P = 0.003).

CONCLUSIONS

Our results suggest that meeting physical activity recommendations has benefits for energy and fatigue even when combined with an otherwise sedentary lifestyle. Moreover, in women who are insufficiently active, being less sedentary is associated with lower levels of fatigue that are comparable with women who are meeting recommendations.

A process-oriented measure of habit strength for moderate-to-vigorous physical activity

Purpose: Habitual action is an important aspect of health behaviour, but the relevance of various habit strength indicators continues to be debated. This study focused specifically on moderate-to-vigorous physical activity (MVPA) and evaluated the construct validity of a framework emphasizing patterned action, stimulus-response bonding, automaticity, and negative consequences for nonperformance as indicators of habit strength for this form of exercise. Methods: Upper-level undergraduates (N = 124) provided demographic information and responded to questionnaire items assessing historical MVPA involvement, current MVPA involvement, and the four proposed habit strength dimensions. Factor analyses were used to examine the latent structure of the habit strength indicators, and the model's construct validity was evaluated via an examination of relationships with repetition history and current behaviour. Results: At a measurement level, findings indicated that the proposed four-component model possessed psychometric integrity as a coherent set of factors. Criterion-related validity was also demonstrated via significant changes in three of the four factors as a function of past involvement in MVPA and significant correlations with the frequency, duration, and intensity of current MVPA. Conclusions: These findings support the construct validity of this exercise habit strength model and suggest that it could provide a template for future research on how MVPA habits are developed and maintained.

Chronic wheel running reduces maladaptive patterns of methamphetamine intake: regulation by attenuation of methamphetamine-induced neuronal nitric oxide synthase

We investigated whether prior exposure to chronic wheel running (WR) alters maladaptive patterns of excessive and escalating methamphetamine intake under extended access conditions, and intravenous methamphetamine self-administration-induced neurotoxicity. Adult rats were given access to WR or no wheel (sedentary) in their home cage for 6 weeks. A set of WR rats were injected with 5-bromo-2'-deoxyuridine (BrdU) to determine WR-induced changes in proliferation (2-h old) and survival (28-day old) of hippocampal progenitors. Another set of WR rats were withdrawn (WRw) or continued (WRc) to have access to running wheels in their home cages during self-administration days. Following self-administration [6 h/day], rats were tested on the progressive ratio (PR) schedule. Following PR, BrdU was injected to determine levels of proliferating progenitors (2-h old). WRc rats self-administered significantly less methamphetamine than sedentary rats during acquisition and escalation sessions, and demonstrated reduced motivation for methamphetamine seeking. Methamphetamine reduced daily running activity of WRc rats compared with that of pre-methamphetamine days. WRw rats self-administered significantly more methamphetamine than sedentary rats during acquisition, an effect that was not observed during escalation and PR sessions. WR-induced beneficial effects on methamphetamine self-administration were not attributable to neuroplasticity effects in the hippocampus and medial prefrontal cortex, but were attributable to WR-induced inhibition of methamphetamine-induced increases in the number of neuronal nitric oxide synthase expressing neurons and apoptosis in the nucleus accumbens shell. Our results demonstrate that WR prevents methamphetamine-induced damage to forebrain neurons to provide a beneficial effect on drug-taking behavior. Importantly, WR-induced neuroprotective effects are transient and continued WR activity is necessary to prevent compulsive methamphetamine intake.

Crawling to the finish line: why do endurance runners collapse? Implications for understanding of mechanisms underlying pacing and fatigue

Effective regulation of pace enables the majority of runners to complete competitive endurance events without mishap. However, some runners do experience exercise-induced collapse associated with postural hypotension, which in rare cases results from life-threatening conditions such as cardiac disorders, cerebral events, heat stroke and hyponatraemia. Despite the experience of either catastrophic system failure or extreme peripheral muscle fatigue, some runners persist in attempting to reach the finish line, and this often results in a sequence of dynamic changes in posture and gait that we have termed the 'Foster collapse positions'. The initial stage involves an unstable gait and the runner assumes the 'Early Foster' collapse position with hips slightly flexed and their head lowered. This unstable gait further degrades into a shuffle referred to as the 'Half Foster' collapse position characterized by hip flexion of approximately 90° with the trunk and head parallel to the ground. At this point, the muscles of postural support and the co-ordination of propulsion begin to be compromised. If the condition worsens, the runner will fall to the ground and assume the 'Full Foster' collapse position, which involves crawling forwards on knees and elbows towards the finish line, with their trunk angled such that the head is at a lower angle than the hips. Upon reaching the finish line, or sometimes before that, the runner may collapse and remain prone until recovering either with or without assistance or medical treatment. The Foster collapse positions are indicative of a final, likely primordial, protective mechanism designed to attenuate postural hypotension, cardiac 'pump' insufficiency or cerebral blood flow deficiency. Continuing to attempt to reach the finish line in this impaired state is also perhaps indicative of a high psychological drive or a variety of neurological and psychological pathologies such as diminished sensitivity to interoceptive feedback, unrealistic situational appraisal or extreme motivational drives. A better understanding of the physiological, neurological and psychological antecedents of the Foster collapse sequence remains an important issue with practical implications for runner safety and theoretical understanding of collapses during exercise.

The effects of stress on physical activity and exercise

BACKGROUND

Psychological stress and physical activity (PA) are believed to be reciprocally related; however, most research examining the relationship between these constructs is devoted to the study of exercise and/or PA as an instrument to mitigate distress.

OBJECTIVE

The aim of this paper was to review the literature investigating the influence of stress on indicators of PA and exercise.

METHODS

A systematic search of Web of Science, PubMed, and SPORTDiscus was employed to find all relevant studies focusing on human participants. Search terms included "stress", "exercise", and "physical activity". A rating scale (0-9) modified for this study was utilized to assess the quality of all studies with multiple time points.

RESULTS

The literature search found 168 studies that examined the influence of stress on PA. Studies varied widely in their theoretical orientation and included perceived stress, distress, life events, job strain, role strain, and work-family conflict but not lifetime cumulative adversity. To more clearly address the question, prospective studies (n = 55) were considered for further review, the majority of which indicated that psychological stress predicts less PA (behavioral inhibition) and/or exercise or more sedentary behavior (76.4 %). Both objective (i.e., life events) and subjective (i.e., distress) measures of stress related to reduced PA. Prospective studies investigating the effects of objective markers of stress nearly all agreed (six of seven studies) that stress has a negative effect on PA. This was true for research examining (a) PA at periods of objectively varying levels of stress (i.e., final examinations vs. a control time point) and (b) chronically stressed populations (e.g., caregivers, parents of children with a cancer diagnosis) that were less likely to be active than controls over time. Studies examining older adults (>50 years), cohorts with both men and women, and larger sample sizes (n > 100) were more likely to show an inverse association. 85.7 % of higher-quality prospective research (≥ 7 on a 9-point scale) showed the same trend. Interestingly, some prospective studies (18.2 %) report evidence that PA was positively impacted by stress (behavioral activation). This should not be surprising as some individuals utilize exercise to cope with stress. Several other factors may moderate stress and PA relationships, such as stages of change for exercise. Habitually active individuals exercise more in the face of stress, and those in beginning stages exercise less. Consequently, stress may have a differential impact on exercise adoption, maintenance, and relapse. Preliminary evidence suggests that combining stress management programming with exercise interventions may allay stress-related reductions in PA, though rigorous testing of these techniques has yet to be produced.

CONCLUSIONS

Overall, the majority of the literature finds that the experience of stress impairs efforts to be physically active. Future work should center on the development of a theory explaining the mechanisms underlying the multifarious influences of stress on PA behaviors.

Voluntary running-wheel exercise decreases the threshold for rewarding intracranial self-stimulation

Physical exercise has mood-enhancing and antidepressant properties although the mechanisms underlying these effects are not known. The present experiment investigated the effects of prolonged access to a running wheel on electrical self-stimulation of the lateral hypothalamus (LHSS), a measure of hedonic state, in rats. Rats with continuous voluntary access to a running wheel for either 2 or 5 weeks exhibited dramatic leftward shifts in the effective current 50 (ECu50; current value that supports half of maximum responding) of their LHSS current-response functions compared to their baselines, indicating a decrease in reward threshold, whereas control rats current-response functions after 2 or 5 weeks were not significantly different from baseline. An inverse correlation existed between the change in ECu50 from baseline and the amount an animal had run in the day prior to LHSS testing, indicating that animals that exhibited higher levels of running showed a more robust decrease in LHSS threshold. We conclude that long-term voluntary exercise increases sensitivity to rewarding stimuli, which may contribute to its antidepressant properties.

The protective effects of voluntary exercise against the behavioral consequences of uncontrollable stress persist despite an increase in anxiety following forced cessation of exercise

Humans who exercise are less likely to suffer from stress-related mood disorders. Similarly, rats allowed voluntary access to running wheels have constrained corticosterone responses to mild stressors and are protected against several behavioral consequences of uncontrollable stress which resemble symptoms of human anxiety and depression, including exaggerated fear and deficits in shuttle box escape learning. Although exercise conveys clear stress resistance, the duration of time the protective effects of exercise against the behavioral consequences of uncontrollable stress persist following exercise cessation is unknown. The current studies investigated (1) whether exercise-induced stress resistance extends to social avoidance, another anxiety-like behavior elicited by uncontrollable stressor exposure, and (2) the duration of time the protective effects of exercise persist following forced cessation of exercise. Six weeks of wheel running constrained the increase in corticosterone elicited by social exploration testing, and prevented the reduction in social exploration, exaggerated shock-elicited fear, and deficits in escape learning produced by uncontrollable stress. The protective effect of voluntary exercise against stress-induced interference with escape learning persisted for 15 days, but was lost by 25 days, following cessation of exercise. An anxiogenic effect, as revealed by a reduction in social exploration and an increase in fear behavior immerged as a function of time following cessation of exercise. Results demonstrate that the protective effect of voluntary exercise against the behavioral consequences of uncontrollable stress extends to include social avoidance, and can persist for several days following exercise cessation despite an increase in anxiety produced by forced cessation of exercise.

Striving for success or addiction? Exercise dependence among elite Australian athletes

Exercise dependence is a condition that involves a preoccupation and involvement with training and exercise, and has serious health and performance consequences for athletes. We examined the validity of a biopsychosocial model to explain the development and maintenance of exercise dependence among elite Australian athletes. Participants were 234 elite Australian athletes recruited from institutes and academies of sport. Thirty-four percent of elite athletes were classified as having exercise dependence based on high scores on the measure of exercise dependence. These athletes had a higher body mass index, and more extreme and maladaptive exercise beliefs compared to non-dependent athletes. They also reported higher pressure from coaches and teammates, and lower social support, compared to athletes who were not exercise dependent. These results support the utility of a biopsychosocial model of exercise dependence in understanding the aetiology of exercise dependence among elite athletes. Limitations of the study and future research directions are highlighted.

Reciprocal inhibitory effects of intravenous d-methamphetamine self-administration and wheel activity in rats

BACKGROUND

Some epidemiological and cessation studies suggest physical exercise attenuates or prevents recreational drug use in humans. Preclinical studies indicate that wheel activity reduces cocaine self-administration in rats; this may, however, require the establishment of compulsive wheel activity.

METHODS

Effects of concurrent wheel activity on intravenous d-methamphetamine (METH) self-administration were examined in male Wistar and Sprague Dawley rats with negligible prior wheel experience. Wistar rats self-administered METH (0.05 mg/kg/inf) under a fixed-ratio 1 (FR1) schedule with concurrent access to an activity wheel during sessions 1-14, 8-21 or 15-21. Control rats which did not self-administer METH had access to an activity wheel during sessions 1-14, 8-21 or 15-28. Sprague Dawley rats self-administered METH (0.1 mg/kg/inf) under FR1 for 14 sessions with either concurrent access to a locked or an unlocked activity wheel.

RESULTS

METH self-administration was lower when the wheel was available concurrently from the start of self-administration training in both strains, even though Sprague Dawley rats self-administered twice as many METH infusions and ran one-sixth as much on the wheel compared to Wistar rats. Wheel access initiated after 7 or 14 days had no effect on METH self-administration in Wistar rats. Wheel activity was significantly reduced in these groups compared with the group with concurrent wheel and METH access for the first 14 sessions.

CONCLUSIONS

These data show that METH self-administration is reduced by exercise if initiated from the start of self-administration and that prior METH self-administration experience interferes with the value of exercise as a reinforcer.

Compulsive exercise and eating disorders

The aim of this review was to develop an empirically supported cognitive behavioural model of compulsive exercise within the context of the eating disorders. A systematic review of the correlates and predictors of compulsive exercise among eating disordered patients identified four key correlates. These were subsequently validated by a second review, incorporating both the clinical and non-clinical as well as the exercise science literatures. A proposed model is presented which is both evidence-based and testable.

Endocannabinoids and voluntary activity in mice: runner's high and long-term consequences in emotional behaviors

The endocannabinoid system participates in the regulation of physical activity, although its role is not yet fully understood. Here, we highlight the impact of endocannabinoid signalling on voluntary wheel running in mice and discuss potential mechanisms involved such as hippocampal neurogenesis. Running-induced short-term and long-term alterations of emotional behaviors are scrutinized with regard to the question how endocannabinoids might be involved. While endocannabinoids seem to contribute to the motivational aspects of voluntary running in rodents, influencing the total distance covered most likely via CB1 receptors, they are less involved in the long-term changes of emotional behavior induced by voluntary exercise.

Differential effects of free versus imposed motor activity on alcohol consumption in C57BL/6J versus DBA/2J mice

Practicing sport regularly provides obvious physiological and psychological benefits, but intensive sport activity, for example, at the competition level, may be associated with an increased risk for addictive disorder, whether to improve results (doping), to tolerate consequences of important pressure and physical activities (drugs), or developing as a substitute when stopping, definitely or temporally, this activity that has been considered as potentially addictive (conversion). An animal model of voluntary versus imposed physical activity is described in which males of two mouse strains with high (C57BL/6J) versus (DBA/2J) low alcohol preference were tested for possible modifications of alcohol consumption during and after physical activity, when the activity was forced versus when it was recreative. Free access to a running wheel allowed a moderate physical activity that was associated with a decrease in voluntary alcohol intake in C57BL/6J mice. On the one hand, forced running at a higher speed than that occurring under free conditions led to increased alcohol intake, back to the initial level. On the other hand, alcohol intake remained at the same low level whether or not DBA/2J mice were subjected to free or forced running. The only effect of forced running in these alcohol-avoiding mice was a significant desynchronization of circadian motor activity rhythm, which was even more pronounced than that induced in alcohol-preferring C57BL/6J mice. These results highlight the positive aspects of moderate and entertaining sport activity and provide further support to the idea that it can decrease spontaneous alcohol intake. They also tend to demonstrate that, at least for vulnerable subjects, forced and intensive activities may not have the same benefits regarding alcohol consumption.

The Relationship Between Physical Activity and Cocaine Intake in Mice

Human studies suggest the existence of an exercise dependency syndrome and a link between drug intake and intense physical activity. Our aim was to assess whether a link actually existed between running activity and cocaine intake in mice. Thirty male Swiss mice were used. Ten mice were used as controls, individually housed in cages without a wheel, and 20 mice were in cages with free access to a running wheel. Cocaine preference was estimated as the ratio (as percent) of cocaine solution intake over total fuid intake in the course of free oral access to cocaine solution versus water. High cocaine scores were only found with high wheel activity. The lowest activity scores were found with low cocaine preference. A group of “high runners” impervious to cocaine appetence and to the effects of exercise withdrawal were found, which may suggest that shared mechanisms could be involved in both dependence on sport and drug taking. Findings suggest that moderate activity seems to be associated with low cocaine preference, and cocaine intake could increase in cases of intense activity. The urge for physical activity (as seen with top-level professional athletes) may theoretically combine with different degrees of vulnerability to cocaine. The use of substances by those engaging in intense physical activity, for performance enhancement or recreational purposes, could potentially trigger a pattern of consumption and addiction. This pattern corresponds with the theory that there may be an addictive element in physical activity. Animal models could prove useful for identifying biological or behavioral predictors of such vulnerability and identifying persons either at risk or possessing resistance.

Psychobiological mechanisms of exercise dependence

Exercise dependence (ED) is characterised by an obsessive and unhealthy preoccupation with exercise. Previous research has focused largely on identifying behavioural aspects of ED, although the biological mechanisms remain unknown and are under researched. We review various ED hypotheses including affect regulation, anorexia analogue, sympathetic arousal and beta-endorphin. We also present a novel hypothesis pertaining to ED and interleukin (IL)-6, which combines previous hypotheses with literature from the field of psycho-neuroimmunology. We explore the notion that IL-6 provides a link from the periphery to the brain, which may mediate the underlying features of ED. We propose a conceptual model indicating that, in individuals prone to ED, exercise results in a transient reduction in negative affect, but concurrently results in excessive production of IL-6 and the activation of neuroendocrine pathways, which are associated with behavioural and psychological disturbances of exercise withdrawal. Our intention is for this model to serve as a basis for further research in the area of ED, which may eventually lead to the development of successful treatment strategies. Recent developments in methods to reliably assess these biological markers from blood and saliva samples should encourage such research to be undertaken in exercise settings.

Heart rate variability as a predictor of negative mood symptoms induced by exercise withdrawal

INTRODUCTION/PURPOSE

Negative mood symptoms occur frequently in sedentary populations, but individual vulnerability factors for developing these complaints have not been systematically evaluated. This investigation examined whether the autonomic nervous system (ANS) serves a role in the development of negative mood after controlled exercise withdrawal.

METHODS

Forty participants (mean age of 31.3 +/- 7.5 yr, 55% women) who exercised regularly (>or= 30 min of continuous aerobic exercise at least three times a week during the past 6 months) were randomized either to withdrawal from regular aerobic exercise (N=20) or to continue regular aerobic exercise (N=20) for 2 wk. Measurements were taken before exercise withdrawal and at 2-wk follow-up. Various dimensions of negative mood were measured with the multidimensional fatigue inventory, profile of mood states, and Beck depression inventory-II. ANS activity was assessed by heart rate variability (HRV) analyses, examining low-frequency (0.04-0.15 Hz: lf) and high-frequency (hf) domains (0.15-0.40 Hz). The lf/hf ratio was used as index of sympathovagal balance. Protocol adherence was documented by ambulatory activity monitoring.

RESULTS

Exercise withdrawal resulted in significantly higher negative mood scores at follow-up compared with control (P<0.05). Baseline lf/hf ratios correlated with the increases in symptoms (r>0.4; P<0.05) in the exercise-withdrawal group independently of gender, age, weight, baseline fitness level, and baseline symptom status. The exercise-withdrawal and control groups displayed no significant change in hf HRV, lf HRV, or lf/hf HRV during the 2 wk.

CONCLUSION

Reduced parasympathetic ANS activity as measured by HRV is predictive of the development of negative mood after deprivation of usual exercise activities. No significant changes in HRV were observed during the 2-wk exercise deprivation period. These findings are relevant to the understanding of mood changes in response to short-term exercise withdrawal, such as sports injuries and recovery from medical procedures.

Effects of abstinence from habitual involvement in regular exercise on feeling states: an ecological momentary assessment study

Regular exercise was experimentally reduced to determine its effects on positive feeling states. Using ecological momentary assessments, 40 participants maintained their regular exercise routine on 3 days and were deprived of their scheduled exercise on 3 other days. They recorded their feeling states, using the Exercise-Induced Feeling Inventory, four times daily as well as prior to and following exercise. Multi-level modelling analyses controlling for diurnal variations in feeling states revealed that positive feeling states were elevated on days when exercise deprivation occurred compared with non-exercise days and when no deprivation manipulation occurred. People with lower exercise dependence symptoms felt better on days when they were deprived from exercise compared with non-exercise days, whereas people with higher exercise dependence symptoms felt about the same when they were deprived from exercise compared with non-exercise days. These findings demonstrate that positive feeling states occur following an acute bout of exercise and that exercise deprivation had a positive impact on feeling states, with the level of exercise dependence symptoms moderating this effect.

Chronic physical activity and feelings of energy and fatigue

This brief review summarizes key epidemiological and experimental evidence concerning relationships between chronic physical activity and feelings of energy (vigor, vitality) and fatigue. The epidemiological studies show a positive association between the amount of typical weekly physical activity reported and the frequency with which people report feeling energetic. The randomized controlled experiments show that 10-20 wk of exercise training is associated with an increase in the frequency and intensity of feelings of energy among fatigued people with medical conditions. The results of longitudinal studies with non-fatigued, healthy adults are mixed. Overtraining by athletes is associated with increased intensity of feelings of fatigue. Additional well-controlled investigations into relationships between physical activity and feelings of energy and fatigue, especially among sedentary and fatigued individuals, are warranted given the available evidence and the importance of these moods to health, work productivity, and quality of life.

Depressive mood symptoms and fatigue after exercise withdrawal: the potential role of decreased fitness

OBJECTIVE

Depressive symptomatology is more prevalent among sedentary than physically active individuals. The present prospective study examines whether withdrawal of regular aerobic activity provokes depressive mood symptoms and fatigue, and to what extent reductions in fitness levels contribute to the development of these symptoms.

METHODS

Forty participants (mean age of 31.3 +/- 7.5 years, 55% women) who exercised regularly (> or = 30 minutes aerobic exercise > or = 3 times/week) were randomized to aerobic exercise withdrawal (n = 20) or to continue regular exercise (n = 20) for 2 weeks. Protocol adherence was documented using ambulatory actigraphy. Negative mood was measured with the Profile of Mood States (POMS), depressive symptoms with the Beck Depression Inventory-II (somatic and cognitive-affective components), and fatigue with the Multidimensional Fatigue Inventory (MFI). Fitness levels were documented by cycle ergometry testing.

RESULTS

Fatigue and somatic depressive symptoms emerged after 1 week of exercise withdrawal (p = .05) and subsequently predicted the development of cognitive-affective depressive symptoms at 2 weeks (beta = 0.62; p = .046). Exercise withdrawal also resulted in increased negative mood (POMS; p < or = .01), and this increase was correlated with decreases in fitness level (r = -0.36, p = .03). Decreased fitness was related to increased POMS fatigue (p = .003) when statistically adjusting for baseline fitness levels and group condition.

CONCLUSION

Depressed mood and fatigue are commonly observed in individuals deprived of usual exercise activities, and the increase in fatigue may be partially mediated by reduced fitness levels. These findings may explain mood changes in response to short-term exercise withdrawal such as injuries and recovery from medical procedures that do not require full bedrest.

The obligatory exerciser: assessing an overcommitment to exercise

A small group of patients are overly committed to their exercise routines, possibly to the detriment of their physical and psychological well-being. The concept of obligatory exercise is difficult to define, and its prevalence has not been extensively studied. Clinicians who are aware of behavioral and personality descriptors for obligatory exercisers can identify the problem and suggest treatment options. Treatment may follow guidelines similar to those for overtraining, addiction, compulsion, and eating disorders. Preventive measures lie in understanding exercisers' attitudes and beliefs about exercise and their bodies.

Voluntary running distance is negatively correlated with striatal dopamine release in untrained rats

This study examined the relationship between voluntary running distance and glutamate- and K+-stimulated dopamine release in the striatum (nucleus accumbens and caudate-putamen) of male Long-Evans rats. Twenty-one rats were housed individually in cages with attached running-wheels for 1 week. There was a 19-fold variability between rats in voluntary running distances over this period (range = 2.3-44.6 km). The average distance completed during the week was 16 +/- 2.8 km. There was a strong positive correlation between the running distances completed during the first 24 h (day 1) and the last 24 h. Certain rats were therefore inclined to run from the start. The average daily running distance (2.4 +/- 0.4 km per day) was negatively correlated with the weight of the rat (r = -0.82). Glutamate-stimulated release of dopamine was not a significant predictor of voluntary running distance. However, the average daily running distance was negatively correlated with K+-stimulated dopamine release in the nucleus accumbens core and caudate-putamen but not the nucleus accumbens shell. The present findings suggest that decreased depolarization-induced release of striatal dopamine may be a predictor of hyperactivity. The results show, in a normal population of Long-Evans rats, that there are, at the end of the continuum, rats that display some of the neurochemical and behavioral characteristics of a rat model for attention-deficit hyperactivity disorder.

Involvement in physical activity and risk for nearly lethal suicide attempts

BACKGROUND

Although substantial research suggests that involvement in physical activity is associated with mental health benefits, relatively little is known about the association between physical activity and suicidal behavior. This study compared reports of recent physical activity among those surviving a nearly lethal suicide attempt to reports from community controls.

METHODS

Analyses were conducted on data collected between November 1992 and July 1995 for a population-based, case-control study of nearly lethal suicide attempts among people aged 13 to 34 years. Logistic regression analyses were used to test the association between suicide attempts and physical activity, including the intensity, frequency, and duration of activity, while controlling for demographic factors and potential explanatory variables, such as depression, alcoholism, and the presence of a serious medical condition.

RESULTS

Suicide attempters were far less likely than controls to report involvement in physical activity in the past month (48% vs 85%, respectively). Intensity, frequency, and duration of activity did not affect this association. The association persisted after adjusting for demographics and potential explanatory variables.

CONCLUSIONS

Additional research is needed to explain the process through which the association occurs. The strong protective association observed is consistent with other research on the mental health benefits of physical activity and recommendations of involvement in regular physical activity.

Transition to university and vigorous physical activity: implications for health and psychological well-being

The authors investigated vigorous physical activity and psychological well-being during transition from high school to first-year university in a sample of 145 Canadian undergraduates. Participants completed retrospective measures assessing vigorous physical activity during their first 2 months at university and their last 2 months at high school as well as measures assessing psychological well-being. According to nationally recommended (US Department of Health and Human Services) standards, two thirds (66.2%) of students reported adequate levels of vigorous activity in high school, whereas significantly fewer (44.1%) met the standard during their first 8 weeks at university. One third of students were active in high school but became insufficiently active once at university; 33% were active at both times; 23% consistently fell short of recommended levels; and only 11% became active once at university. Students who had become insufficiently active reported higher levels of fatigue and lower levels of vigor compared with those who continued to be active.

Wheel access duration in rats: II. Day-night and within-session changes

Time of day and duration of wheel access were manipulated to see how running changed over days. Young male rats were given 2 hr of wheel access, during either the light or dark phase. Over 24 days, running increased 4-fold in the dark group but remained low and stable in the light group. With rats given either 1 or 4 hr of dark phase wheel access, running increased much more in the 4-hr group (even in Hour 1) than in the 1-hr group. The within-session running pattern for high runners changed from a habituation to a sensitization profile. Running and cocaine self-administration (S. H. Ahmed & G. F. Koob, 1998, 1999) are affected similarly by session length, suggesting running as an interesting addiction model.

A prospective analysis of the relationship between walking and mood in sedentary ethnic minority women

Walking for exercise is becoming widely recognized for bestowing health benefits. This study examined the association of walking for exercise and mood in sedentary, ethnic minority women over a five-month period. Ethnic minority women (N = 102) participated in a randomized, controlled trial of a 7-week behaviorally based telephone and mail intervention that promoted the adoption of walking for exercise compared to a non-behavioral minimal intervention. At 2-month post-test and 5-month follow-up, participants reported significant decreases in depressive mood and increases in vigor. Increase in walking over the course of the study was associated with change in vigor. Limited evidence was found to support a relationship between walking for exercise and mood improvement in ethnic-minority women.

Effects of physical exercise on anxiety, depression, and sensitivity to stress: a unifying theory

Until recently, claims for the psychological benefits of physical exercise have tended to precede supportive evidence. Acutely, emotional effects of exercise remain confusing, both positive and negative effects being reported. Results of cross-sectional and longitudinal studies are more consistent in indicating that aerobic exercise training has antidepressant and anxiolytic effects and protects against harmful consequences of stress. Details of each of these effects remain unclear. Antidepressant and anxiolytic effects have been demonstrated most clearly in subclinical disorder, and clinical applications remain to be exploited. Cross-sectional studies link exercise habits to protection from harmful effects of stress on physical and mental health, but causality is not clear. Nevertheless, the pattern of evidence suggests the theory that exercise training recruits a process which confers enduring resilience to stress. This view allows the effects of exercise to be understood in terms of existing psychobiological knowledge, and it can thereby provide the theoretical base that is needed to guide future research in this area. Clinically, exercise training continues to offer clinical psychologists a vehicle for nonspecific therapeutic social and psychological processes. It also offers a specific psychological treatment that may be particularly effective for patients for whom more conventional psychological interventions are less acceptable.

Assessment of state and trait anxiety in subjects with anxiety and depressive disorders

The State-Trait Anxiety Inventory (STAI) is one of the most widely used scales for the evaluation of anxiety in medical and, to a lesser extent, psychiatric patients. Although there is a relatively large amount of STAI data about anxiety for individuals with a variety of psychiatric disorders, the results of many anxiety studies include only state or trait and many studies have been influenced by comorbidity and by variations in diagnostic criteria used. We studied state and trait anxiety and compared the revised form of the STAI (Form Y) with the original (Form X) to evaluate the anticipated improvement in the measure. In addition, we compared the STAI results with those of another self-report measure (the Symptom Checklist-90 anxiety and depression scales) and also with interviewer-rated measures of anxiety (Hamilton Rating Scale for Anxiety) and depression (Hamilton Rating Scale for Depression). Results indicate that the STAI does not clearly differentiate anxiety disorders from depressive disorders and support the use of multiple tests and of both self-report and interviewer ratings in the evaluation of anxiety and depression in psychiatric patients.

Running and cocaine both upregulate dynorphin mRNA in medial caudate putamen

Physical activities such as long-distance running can be habit forming and associated with a sense of well-being to a degree that justifies comparison with drug-induced addictive behaviours. To understand molecular similarities and dissimilarities controlling these behaviours in humans we compared the effects of running in running wheels to the effects of chronic cocaine or morphine administration on mRNA levels in brain reward pathways in the inbred Fischer and Lewis rat strains. These strains are both inbred from the Sprague-Dawley strain; Lewis rats display a higher preference towards addictive drugs and running than do Fischer rats. After chronic cocaine or running a similar increase of dynorphin mRNA in medial caudate putamen was found in the Lewis rat, suggesting common neuronal adaptations in this brain region to both cocaine and running. Fischer and Lewis rats both responded to cocaine with increased dynorphin mRNA levels in medial caudate putamen. However, only Lewis rats increased dynorphin mRNA after running, possibly reflecting the much higher degree of running by the Lewis strain as compared to the Fischer strain. Moreover, the running-induced upregulation of dynorphin mRNA was blocked by the opioid receptor antagonist naloxone. We suggest that running increases dynorphin mRNA by a mechanism that involves endogenous opioids. The voluntary wheel-running model in rats might be used to study natural reward and compulsive behaviours and possibly also to screen candidate drugs for treatment of compulsive disorders.

Emotional states and physical health

Positive emotional states may promote healthy perceptions, beliefs, and physical well-being itself. To explore potential mechanisms linking pleasant feelings and good health, the authors consider several lines of research, including (a) direct effects of positive affect on physiology, especially the immune system, (b) the information value of emotional experiences, (c) the psychological resources engendered by positive feeling states, (d) the ways in which mood can motivate health-relevant behaviors, and (e) the elicitation of social support. As anticipated by the Greek physician Hippocrates, positive emotions and healthy outcomes may be linked through multiple pathways.