Shoes should be comfortable and any walking aids that the patient ordinarily uses should be used. The patient should rest comfortably for 10 minutes prior to the test. During this time blood pressure and heart rate should be measured and potential contraindications assessed. Pulse oximetry is optional. If it is used, it should be ensured that readings are stable prior to starting the 6 MWT, and signal is optimized. The Borg scale may be used for this.
Set the lap counter to zero and timer to 6 minutes. Assemble all necessary equipment and move to starting point. The supervisor may walk a lap to demonstrate performance of the test to the patient. The supervisor may walk behind the patient to support the patient in case of staggering or to prevent falling.
Use standardized phrases and an even tone for encouragement at completion of each minute of the test. For an example of a standardized script, the reader is referred to the ATS guidelines. If the patient cannot go any further, the test should be stopped and distance covered recorded. Test supervisors should be trained to provide appropriate care at this point. Record the reason for stopping the test. If the patient is on supplemental oxygen, use the same oxygen level that he or she normally uses with exercise.
The ATS guidelines do not recommend routine measurement of pulse oximetry during the test. With the widespread availability of light-weight portable oximeters, monitoring of oxygen saturation during walking can be reliably performed.
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Quality control and standardization are important to reduce variability in measurement. Persons supervising the test should be trained using a standard protocol, and should conduct supervised 6 MWTs before they are able to perform them independently. A practice test generally should not be needed. If a practice test is done, there should be a wait time of about an hour between the two tests, and the longer 6 MWD should be reported. Several studies have shown that walking distance tends to increase with repeated test administration due to familiarization or learning effect.
Estimates for this learning effect have ranged from 4. The initial learning effect has been shown to be maintained over at least 2 months of follow-up. Interpretation of results is guided by whether the test is used for prognostication, assessment of functional status or therapeutic monitoring. A single value of 6 MWD can be reported as an absolute value or as a percent predicted for age and gender. For prognostication, 6 MWD can be compared to published values for the particular disease category.
Changes in 6 MWD over time can be reported as absolute difference, percentage change or change in percentage predicted. When evaluating changes in 6 MWD with treatment, some investigators have advocated the concept of minimal clinically important difference MCID i. However, no broadly applicable data on what constitutes a reasonable MCID exist, and MCID may vary by disease category and severity, and other characteristics of the patient population. A m increment over a baseline 6 MWD of m may be more important than the same increment over a baseline 6 MWD of m.
Expressing percentage change in 6 MWD may be more helpful in this setting. In our clinical practice, we have also found that expressing 6 MWD as percentage of normal predicted values is helpful. The role of the 6 MWT in various cardiovascular conditions as a prognostic marker and for predicting response to therapy is profiled below. This may reflect problems with assessment of either. In this study the mean change in 6 MWD for small improvement in symptoms 19 m was not statistically different from no change.
However, improvements in 6 MWD with cardiac resynchronization therapy CRT have been more consistent, and estimates have ranged from 5 to 74 m. This may be a reflection of selection of sicker patients in trials for CRT. Earlier trials of CRT were also limited by lack of patient or investigator blinding to treatment allocation. Six MWD is independently related to mortality in patients who are on treatment as well. Those patients who achieve a threshold of m have improved survival, irrespective of their baseline 6 WMD.
The relationship between walked distance and mortality may not be seen in patients with untreated PAH, where desaturation during the 6 MWD may be a better predictor of mortality. Exercise capacity is an important outcome in trials of drugs for PAH. Change in 6 MWD has been accepted by regulatory agencies as an endpoint in randomized controlled trials of drugs for PAH.
The 6 MWT is commonly used in cardiac rehabilitation for exercise prescription and as a metric to monitor improvement in functional status. Test-retest reliability has been reported as high. Intraclass correlation coefficients ICC were reported as 0.
ICC in cardiac rehabilitation patients has been reported to be as high as 0. With a good quality-assurance program, with patients tested by the same technician, and after one or two practice tests, short-term reproducibility of the 6 MWD is excellent. Distances reported for healthy individuals ages 40 to 85 years range from to m see references. Using consistent language when describing the aspects of stress and its measurement — and using a theoretical lens to do so — is important for building a cumulative science of stress and harmonizing around critical theoretical dimensions.
For example, the seminal meta-analysis by Dickerson and Kemeny evaluated more than studies and identified that social-evaluative threat was the key ingredient for situations that elicit cortisol increases. Few other conceptual dimensions of stress have been identified as being essential in understanding and explaining the impact of stress on health and well-being. Often these two concepts are confused or conceptualized as overlapping.
In the following sections we describe characteristics of stressor exposure and stress response that are important to consider conceptually and methodologically. These are the components included in the Stress Typology. One of the most defining characteristics of a stressor is duration. Here we describe four timescales—acute stressors, daily events, life events, and chronic stressors. Acute stressors are intense short-term exposures. These are typically examined under standardized laboratory conditions but can be examined as naturally occurring events, with lower granularity due to limitations of measurement in the field.
There is some stability in daily emotional stress responses, at least in midlife, and these may weaken with age Sliwinski et al. There are many factors that influence daily reactivity. For example, EMA studies have shown that anticipation of stressors leads to more negative affect Neubauer et al. Rumination also prolongs reactivity. Rumination predicts greater cortisol reactivity in response to an acute stressor, and higher cortisol that evening Zoccola and Dickerson, ; Puterman et al.
Inducing rumination after a stressor leads to greater vasoconstriction and prolonged blood pressure recovery Ottaviani et al. In contrast, mindful acceptance training can lead to less exaggerated cortisol and blood pressure reactivity responses to a standardized stressor Lindsay et al.
Acute stressors are described in detail in Part 5. When someone faces the same daily stressors frequently, whether the actual event or just threat of the event, this can be considered a type of chronic stressor. In turn, to understand how chronic stress emerges at a daily level, we can examine the daily lives and daily stressful events of those under chronic stress. Life events are time-limited and episodic in nature, such as getting into an accident, being laid off, being broken up with, or receiving a life-threatening diagnosis.
Life events can be events that seem positive on the surface but are in fact quite demanding such as getting promoted at work or getting married. These circumstances occur in a specific moment in time, with an identifiable onset. Although the actual event can be relatively brief, events can have varying long-term consequences, depending on the nature of the event and its sequelae, especially in relation to initiating chronic stressors.
Examples are witnessing or experiencing violence, the death of a loved one, experiencing abuse, or experiencing a natural disaster. A greater number of traumatic events across the lifespan is associated with worse self-reported health, greater health care utilization, functional disability, arthritis, greater number of acute and chronic illnesses, and mortality Gawronski et al.
Experiencing trauma in childhood is particularly deleterious for health; there is strong evidence that early childhood adversity is associated with higher rates of illness in adulthood including cancer, depression, cognitive decline, and premature mortality Brown et al. Specific life events like losing a job can initiate chronic stressors, such as persistent financial difficulties, although this is not always the case. Likewise, specific chronic stressors, such as living in an unsafe neighborhood, can give rise to different life events, such as being a victim of crime, but again, this is not always the case Brown and Harris, The criteria for the duration of a situation for a chronic stressor vary greatly.
We suggest that a situation should be ongoing for at least six months to be considered chronic, although longer periods one year or more will lead to a more stringent criteria for whether a chronic stressor might have long term health effects. Chronic stress can be defined in other ways besides quantifying duration.
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When a daily stressor stems from the same ongoing situation, this is conceptualized as a form of chronic stress. Empirical evidence shows that chronic stress in this form is associated with high negative and low positive daily affect Koffer et al. The different timescales are nested within each other as depicted in Fig.
In other words, if you are already experiencing a chronic stressor such as financial strain, job insecurity, or being a caregiver , you are more likely to report a greater number of daily stressors and greater general perceived stress at any timepoint as demonstrated below with a caregiver sample. Furthermore, on a monthly basis, those under chronic stress will also report more frequent or severe major life events, and greater peaks of perceived stress responses during those times, greater variability, and greater mean perceived stress over time.
In sum, being under chronic stress puts you at greater risk for experiencing a greater number and more severe life events and daily hassles, and reporting greater perceived stress at any given moment. This figure describes how different time scales of stressor exposure — months, daily, momentary — are nested within each other. In short, chronic stressor exposure shapes how an individual perceives daily or acute stressors. A second characteristic of stressor exposures is the life period in which the stressor exposure occurred. Stressors occur at any time of life, beginning with in utero, a critical period.
The impact on mental and physical health depends partly on the developmental phase Andersen and Teicher, ; Masten and Narayan, Stress during fetal development has imprinting effects on adult mental and physical health Barker, ; Van den Bergh et al. Early childhood is another critical period Lupien et al. Severe stress chronic or traumatic stressors in childhood is associated with vulnerability to psychological and physical illness in adulthood, including depression, lung disease, heart disease, diabetes, cancer, and premature mortality Anda et al.
Most of the research in this area has focused on the long-term impact of severe forms of early adversity, such as physical or sexual abuse, though less severe and more common forms of early adversity such as disrupted parent-child relationships have also been associated with worse health in adulthood Russek and Schwartz, The pathway from early life stress to disease development may be mediated by early changes in neural pathways regulating stress, such as amygdala connectivity e.
The majority of research thus far has focused on differentiating childhood from adulthood experiences of stressful life events and chronic stressors, though researchers are now focused on identifying smaller units of time that are important in a developmental context e. Late adulthood stressors are also important in that people have lower homeostatic capacity, physiological resilience, as well as less coupling between their internal and external stimuli Mendes, described in Section 6.
Summing up exposures from across the lifetime is theoretically important and allows us to test the importance of a linear dose response model. It may also be that those with early adversity are more impacted by later life events, a double hit model, although there is little research so far testing this.
Most studies examining links between lifespan stressors and health have relied on trauma checklists which often do not capture major stressors that are not considered traumatic, such as moving, the breakup of a relationship, or getting fired from a job, and it is not clear how important these stressful but normative life events are. A life course perspective can help us understand both cumulative stressors as well as whether one event will have a severe impact. The life course perspective takes into account the examination of individuals over time, their social roles, historical and cultural contexts, and biologically sensitive critical periods.
It can help us understand the typically greater adverse events in those of low socio-economic status, starting from childhood.
Social disadvantage leads to a cumulative disadvantage and helps explain certain events such as unplanned teen pregnancy, which is a result of many differences in opportunities and decisions over time, rather than being a singular event Elder, In turn that event makes other events more likely, such as dropping out of school and economic hardship. Social role stress becomes particularly important in mid to older life, when people are engaged in work, parenting, and multiple social roles, before aging related diseases or disabilities take their toll, and these work roles can have positive effects on health.
While role strain can occur with too many social roles, in general, having many work and social roles predicts better mental and physical health Nordenmark, Retirement can have positive or negative effects on health, depending in part on whether it is forced or voluntary, and the subjective meaning of retirement for the person Moen, When considering how much impact stressful life events have on health, events have different effects at different developmental periods of life.
There are sensitive periods when people are biologically more vulnerable to stressors. There are also socially sensitive developmental periods. For example, retirement and caregiving in later years do not violate expectations of aging and thus may be easier to adjust to, whereas caregiving for a special needs child as a young or midlife parent often violates expectations.
Midlife is a time characterized by high career and social demands with which chronic caregiving responsibilities conflict. For similar reasons, loss of a spouse and natural disasters have bigger impacts on people in midlife than older age Bonanno and Kaltman, The third characteristic of stressor exposure is the assessment window, meaning the timeframe of the tool being used e.
The second category of the Stress Typology is the psychological and behavioral responses to the stressor. These responses may be the most proximal determinants for engaging in healthy or unhealthy behaviors to seek relief from a stressor. Stress is not a singular construct wherein stressors of different types have similar effects on health. Rather, stress research has shown that some types of stressors are particularly deleterious. Additionally, different situations can evoke distinct social and psychological responses.
Other work has focused on the degree of controllability that different stressors possess Maier and Watkins, Stress responses can be closely examined using standardized lab stressors. Lab stressors, while not naturalistic, are invaluable tools because they allow us to manipulate and understand contextual effects as well as physiological, cognitive, and affective responses as they unfold during a stressor.
They also reveal whether an individual has an embedded exaggerated or blunted stress response. Catching the onset of a stressor in the field is difficult. Technological innovations that utilize ecological momentary assessment EMA and bio-sensing tools will allow the capture of both psychological and physiological states, and passive contextual data throughout the day. Importantly, however, these measures will have limited ability to capture stress trajectories until they can capture the onset, peak, and recovery parameters of responses to daily events.
A further description of acute stressor tasks and responses is presented in Section 6. We offer an example of the interaction of stressor type by looking at a sample that is defined by caregiver status. Caregiving for an ill or disabled family member is a model often used in chronic stress research. Caregiving is stressful because it requires daily, and sometimes moment-by-moment, intense caring for someone else who may have difficulty managing physical, behavioral, and cognitive needs, which at the same time limits time for self-care and paid work. If one has few financial resources, common stressful events may have a bigger impact.
Caregivers tend to have high rates of anxiety and depression and poor physical health. We have studied the life events, daily stressors and perceived stress responses of caregiving mothers of children with an autism spectrum disorder a chronic stressor and mothers of neurotypical children over 3 weeks, each week separated by nine months. This included roughly women, described elsewhere Catalino et al. First of all, the caregivers reported much higher global perceived life stress Cohen et al.
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Caregivers also reported a greater number of stressful life events in the past year compared to controls. When shifting to examining daily stress, we can assess whether a well-defined chronic stressor caregiving predicted more daily stressful events. Extrapolating to over a year, this would lead to 35 more days with a moderately stressful event per year, roughly an extra month of moderately or highly stressful days, compared to controls.
Both controls and caregivers reported higher nightly perceived stress on the days they had a significant stressor, with caregivers showing higher levels than controls Caregivers: 1. Caregivers also had larger increases from their baseline perceived stress levels on non-stressor days even though they had a relatively high baseline baseline levels: Caregivers: 1. As shown, the mean perceived stress level on a high stressor day for controls was similar to the mean nightly stress level on a low stressor day for caregivers.
This is not just significant to the psychological wellbeing of the caregivers, because such an increase in number of daily stressors may help explain the greater systemic inflammation in caregivers compared to controls Gouin et al. Chronic stressors have an important place in stress science. There is a strong relationship between experiencing chronic stress and health-related outcomes, including biomarkers of disease, early disease conditions, and in some cases, mortality. The chronicity of a stressor — the length of time the event and its aftermath continue for — is a major factor determining the extent of its effects on health.
Furthermore, chronic stress acts as a background or contextual layer for which individuals encounter other types of stressors daily hassles, acute events , increasing the likelihood that they will not have the resources to cope as efficiently with the additional stressors see Fig. There are many reasons someone may be under chronic stress. Decades of stress research have examined the impact of a wide range of difficult and demanding experiences, referring to these experiences with different terminology such as chronic strain, ongoing stressors, and chronic stress.
We use the term chronic stress to mean any experience that is demanding and distressing nearly every day for 6 months or more. We reviewed the literature linking chronic stress to health outcomes and identified types of chronic stressors that have extensive evidence linking them to disease and mortality.
These types are: neighborhood environment, financial strain, interpersonal stress i. In Appendix 2 , we list exemplar studies linking these experiences of chronic stress to physical health outcomes, pulling from epidemiological studies and meta-analytic evidence when possible. We present only positive findings in the table and have selected representative studies rather than presenting a complete review of all relevant research.
A particularly important type of chronic stressor is one that is interpersonal in nature. There is an abundance of work suggesting that social interpersonal stressors are particularly harmful for health, given the fundamental motivation for humans to form and maintain close social bonds Baumeister and Leary, ; Gilbert, ; Slavich et al.
Interpersonal stressors are amongst the strongest predictors of emotional distress, systemic inflammation, poor health, and survival e. Interestingly, social stressors that involve an element of rejection feeling excluded from a social group have a notably large impact on future depression Slavich et al.
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The primary social stressors found to be associated with worse health are social isolation, loneliness, relationship conflict, and discrimination. Links between these chronic stressors and health are outlined in Appendix 2. Financial strain is another important chronic stressor as level of financial resources are known to predict health, across the socio-economic SES gradient.
Results from the nationally representative Health and Retirement Study HRS show that lower SES during both childhood and adulthood predict worse self-rated health, greater chronic conditions in later life Luo and Waite, , and increased mortality Galobardes et al. In addition to measuring objective resources by SES indices, it is important to measure perceived financial strain, which is a relative measure and can exist at any level of SES. In HRS, perceived financial strain predicted earlier disability Matthews et al. Exposure to these chronic stressors is important but equally important is the psychological response to the stressor.
One example of this basic principle has been demonstrated by research on caregivers. Mere exposure to caregiving is predictive of some negative outcomes, particularly because it tends to be ongoing for many years, but the distress associated with caregiving is often more predictive. For example, in a classic study on caregiving stress, older adults were followed over five years. In another study of younger maternal caregivers, when compared to age-matched controls, the two groups had similar telomere length and oxidative stress.
However, greater perceptions of global perceived stress among the caregivers was associated with a worse biomarker profile Epel et al. To measure chronic stress well, characteristics of the stressor e. These measurement components are outlined further in the Appendix 1. Most of the chronic stress measures included in epidemiological studies capture current experiences within selected life domains and therefore miss past experiences and cumulative experiences across the lifespan.
Cumulative lifetime stressor exposure is important as several theoretical models suggest that the impact of stress accumulates over time, with greater exposure leading to more health problems. However, cumulative life stress is time intensive and burdensome to measure and thus has not been captured in most epidemiological studies. Furthermore, the validity of retrospective measures is inherently an issue, and childhood trauma questionnaires have been examined in this regard. Studies directly comparing retrospective and prospective reports of adverse childhood experiences have found slight to fair agreement rates reviewed in Newbury et al.
Self-reports of lifetime stressors, including childhood traumas, are typically assessed many years after their occurrence, introducing biases such as forgetting or infantile amnesia, inaccuracy regarding the timing of events, or mood-congruent memory that result in underreporting of childhood adversity estimates reviewed in Hardt and Rutter, Overall, prospective measures show better psychometric properties and prospective cohort studies are clearly of advantage. Despite the limitations of retrospective measures of historical life stress exposure, studies relying on retrospective reports of cumulative life stress have been illuminating in showing that lifetime stressor exposure negatively affects health-related processes and outcomes, including autonomic nervous system activity Lampert et al.
In the Health and Retirement study, a retrospective measure of life events across the lifespan has been examined and childhood versus later life stressors have been compared. When broken down by life period, childhood adversity had a significant effect on proinflammatory gene expression Levine et al. To address the need to capture a stressor exposure across the lifespan without lengthy in-person interviews, an automated, computer-based interview method was developed. The stressors that are assessed cover all major life domains e. Cumulative life stress measured with the STRAIN has so far been associated with worse health, including poor self-reported physical health Toussaint et al.
There is great variability in individual responses to stressors. One key component of both psychological and physiological responses to potentially stressful events or stimuli is cognitive appraisals see Fig. There are several types of stress appraisals that have been identified to influence acute stress reactivity, and fewer that have been identified to shape responses to chronic stress.
Classic dimensions from animal and human research that shape acute stress reactivity include evaluations of the situation as novel, unpredictable, and uncontrollable Mason, Other stress appraisals that offer potential insight into links between stressor exposure, reactivity, and aging include appraisals of the stressor as a threat vs. The idea that some types of stress responses might be beneficial or adaptive has a long history in stress research.
Psychological states of challenge compared to threat have been conceptualized as a relative ratio between the demands of a situation — the psychological or physical danger present, the uncertainty or novelty of a situation, and the required effort — and the personal resources to cope—individual and dispositional styles, social support, and knowledge and abilities Blascovich and Mendes, A situation can be demanding because the stakes are high, it is novel, and requires effort to do well, but to the extent that someone has experience more familiarity , feels supported, has well-honed abilities, or is knowledgeable about the topic, they can off-set the demands.
As a heuristic, to the extent that demands exceed resources, a threat state is expected, whereas when resources meet or exceed demands a challenge state is anticipated. This distinction between threat and challenge offers a way for researchers to interpret how the same stressor might be harmful for some but not all people, and that some stressors might in fact be beneficial Sapolsky, ; Seery et al. Additionally, threat and challenge appraisals are an important and powerful area of stress research given that appraisals are modifiable Jamieson et al.
Threats to physical survival and safety have been shown to dysregulate the HPA axis and other physiological systems in animals and humans Sapolsky et al. Threats in the daily environment likely influence biological functioning. Evidence to support this point include studies showing that subjective appraisals of neighborhood safety and disorder e. Negative social evaluation social-evaluative threat in the context of an uncontrollable performance acute stress task is a particularly powerful HPA axis activator Dickerson and Kemeny, Negative social evaluation also elicits autonomic nervous system activation, proinflammatory cytokine increases, and self-reported negative affect Akinola and Mendes, ; Bosch et al.
The importance of appraisals in responses to chronic stressors has received significantly less attention.
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Importantly, there are also stress appraisals that have beneficial effects on health, or on the ability to endure the stressor, such as seeing a stressor as beneficial benefit finding or meaningful Moskowitz et al. Chronic stress is often characterized as an oppressive, unremitting long-term aversive state that can accumulate and lead to poor psychological and physical health. In contrast, acute stress occurs over a shorter period of time and typically has a relatively clear start and end point.
In general, chronic stress occurs on a time scale of weeks, months and potentially years, whereas acute stress occurs over minutes and maybe hours. Although repeated acute stressors experienced over a long period of time days, weeks, months might become chronic stressors — for example a discriminatory work environment where every day a superior is disparaging toward an employee — acute stressors differ from chronic stressors in many critical aspects. Here we review how acute stress is conceptualized, the affective, cognitive, and developmental factors that modulate acute stress, the biology underlying acute stress responses, the short and long term consequences, and how acute and chronic stress influence one another.
Acute stress is characterized by the occurrence of a specific eliciting event. This event can be an identifiable, punctate situation, like a job interview or public talk, or something more diffuse like a first date. The responses to the event flow through conscious processes, like appraisals, and also through unconscious processes that exert influences on the brain and body without explicit awareness Bechara et al. The stressor type, how the stressor is coped with or regulated, and contextual factors, determine the immediate physiologic response, as well as the behavioral and long-term consequences.
One feature that is important is whether the event is active or passive Blascovich and Tomaka, ; Lawler et al. Active events are defined as evocative situations that require an instrumental response. In a laboratory setting, active stressors include spontaneous speeches, reaction time tasks, or evaluated mental arithmetic. In real world settings, active stressors include events such as job interviews, public speaking, test taking, work and relationship-related discussions. Passive stressors are evocative situations that are experienced without any instrumental response requirement.
In a laboratory setting passive stressors include watching disturbing films or experiencing an unavoidable shock. In real world settings, passive stressors include events like watching a loved one experience something difficult, having dental work performed, or waiting for test results. In active stressors mobilizing metabolic energy to devote to the task at hand could be viewed as functional, whereas in passive tasks recruitment of metabolic energy is less likely to serve a functional purpose and ultimately could be more health damaging.
For example, Obrist argued that attempts to cope with passive stressors, such as inevitable pain, could exacerbate painful experiences by creating greater muscle tension. Iwata and LeDoux found that when rats were conditioned to expect an electric shock, their physiological responses changed based on whether they were unrestrained and escape was presumably possible versus restrained with no possibility of escape. Unrestrained compared to restrained rats showed greater sympathetic arousal and lower blood pressure reactivity prior to an electric shock, consistent with the idea that greater SNS activation provides more oxygenated blood to the periphery to enhance flight, which would be adaptive in the unrestrained condition.
Thus, for human stress measurement interpretation, it is critical to understand the context of the stressor, and the possible functions of the response. It cannot be assumed that physiologic arousal or activation in response to an acute stressor is health damaging. Controllability is also an important feature of the stressor and can alter appraisals of the event and responses to it. In a meta-analysis of cortisol reactivity, tasks coded as motivated performance situations i. The metabolic demand required during a stressor needs to be considered to interpret the physiologic consequences.
Some acute stress tasks inherently require metabolic demand that by itself activates physiological responses. Therefore, the changes in physiologic responses might be a combination of the metabolic demands and the psychological state induced by the stressor. In some situations the metabolic demand is obvious.
For example, standing versus sitting during a speech delivery task differentially affects blood pressure given that sitting blood pressure is lower than standing blood pressure. Further, mentally preparing to give a speech versus delivering a speech differentially affects respiration and heart rate variability. Some metabolic demands of the task are less obvious yet can influence physiology and obscure the extent to which the psychological state of stress is affecting physiologic changes. For example, greater cognitive effort increases blood pressure and heart rate responses in a linear, monotonic manner Wright and Kirby, To the extent that a stressor is more cognitively demanding than other tasks, or difficult for some people and not others, it might differentially increase blood pressure and heart rate responses not because of the experience of stress, but because the task is more cognitively difficult.
Cortisol levels also increase during more cognitively demanding tasks Lovallo and Thomas, Instead, considering the task demands, examining the profile of the responses, temporal aspects related to response, and habituation and recovery, provides a more comprehensive portrait of the acute stress response. How the body and mind respond to a stressor can have short and long-term consequences on behavior and health. One way to begin to differentiate stress types and stress responses physiologically is to consider the profile of responses across systems.
Several theories have attempted to differentiate acute stress responses into broad categories of beneficial and harmful responses e. Dienstbier, ; Frankenhaeuser, ; Henry, For example, as reviewed earlier, challenge states occur when individuals appraise their resources as exceeding the demands of the task, whereas threat states occur when situational demands are perceived to exceed resources as described in Part 5 above. These responses are considered profiles because there are multiple physiologic responses—one single physiologic response is insufficient—the theory makes predictions regarding both the direction and the relative intensity of the response, and there are specific expectations of the temporal nature of the responses.
Specifically, even though both states are characterized by sympathetic nervous system activation, challenge is characterized by increases from a resting state in cardiac output CO, the total volume of oxygenated blood the heart pumps in a minute and decreases in total peripheral resistance TPR —vasodilation. Challenge states have quick SNS responses and habituate during a task, whereas threat states have slower rise in SNS upon exposure to the task and SNS tends to stay elevated for a longer portion of the task. Research has identified benefits of challenge states compared to threat states in cognitive performance, emotional responses, and health.
For example, challenge, relative to threat, states have been associated with better decision-making Kassam et al. Larger increases in sympathetic activation commonly measured using changes in ventricle contractility, a relatively pure measure of sympathetic activation, or changes in catecholamine levels such as epinephrine also tend to produce better performance in physical and cognitive tasks. For example, students preparing to take the GRE were assigned to either a stress reappraisal manipulation, which encouraged participants to interpret their physiological arousal during test-taking as a beneficial response that would enhance cognitive performance or a no-instruction control condition.
Reappraisal participants exhibited a larger increase in sympathetic activation measured with salivary alpha amylase immediately before taking a practice GRE and performed better at the math exam than those who were assigned to the control condition. Indeed, consistent with the challenge and threat framework, the greater the SNS increase the better the math performance see also Dienstbier, , for additional examples. Furthermore, the reappraisal participants, compared to control, earned higher GRE exam scores when they took the actual test in the following months Jamieson et al.
These relationships are consistent with the physical activity literature where higher activation is associated with better performance with little evidence of a U-shaped relation. Although the mechanisms through which long term health benefits of challenge have not yet been specified, there is cross sectional and longitudinal data suggesting that benign challenge responses may accumulate over time to produce more positive health outcomes.
In the Framingham Heart Study sample of more than participants Jefferson et al. These researchers speculated that increased oxygenated blood produced by the heart may have long-term protective effects in the brain. These data point to the intriguing, albeit preliminary, suggestion that repeated threat reactivity during acute stress might speed biological aging. Lastly, psychological and physiological profiles of threat and challenge may have implications for behavior change. Acute stress reactivity profiles may lead to latent behavioral tendencies.
For example, motivational states of engagement should facilitate proactive behaviors like exercise , whereas motivational states of inhibition may lead to more passive coping such as eating or substance abuse to modulate negative emotions. We build on a very similar model proposed by McEwen which focused on responses to repeated events and, implicitly, on HPA axis activation. The acute reactivity approach to understanding health outcomes makes assumptions regarding how affective experiences bring about acute changes reactivity in biological systems, which might accumulate over time to induce excessive wear and tear on biological health via allostatic load McEwen, Scholars who use this approach typically expose participants to standardized tasks like watching videos, giving evaluated speeches, and engaging in social interactions that activate physiologic changes, and interpret the profile of the resulting activation as maladaptive or harmful to health.
For example, in a study in which women described being unjustly accused of shoplifting, African American women who reported experiencing past discrimination had greater diastolic blood pressure than African American women who reported little experiences of prior discrimination in their lives Guyll et al. Although the general reactivity hypothesis is intriguing, it likely cannot yield the full story on how acute reactivity affects health.
Thus, reactivity might be part of the pathway from affective experiences to health outcomes, but the simple interpretation that greater reactivity in the lab provides a snapshot of typical reactivity in daily life is not sufficient. Intensity of reactivity provides an initial picture of how individuals respond, but examining a more dynamic profile over time may provide a more comprehensive understanding. McEwen, A maladaptive or unhealthy response in anticipatory reactions would be characterized by a heightened response prior to the onset of an event top left graph.
As depicted in Fig. This could be a function of having negative expectations for a social interaction, test, or job interview, which might be reflected in increased vigilance or anxiety. These negative expectations might be especially harmful when transitioning to new environments. Unhealthy psychological and physiologic responses can also be characterized by the lack of recovery once a stressor is over. Rumination, in particular, has been implicated in poor post-stress recovery Brosschot et al.
In contrast, a lack of habituation during a stressor bottom left graph might reflect an inflexibility of the system to quickly adapt, which may also ultimately create excessive wear and tear. To the extent that some individuals are hyper-vigilant during a task either due to stigmatized status or individual differences like fear of evaluation or rejection-sensitivity, they might show less habituation to a stress task.
Finally, although we have focused primarily on trajectory of physiologic responses to acute stress this approach could be easily adapted to encompass psychological reactions e. Anticipation, for example, can be characterized psychologically as worry, whereas blunted recovery indicates rumination or preservative thinking.
Lastly, strong activation physiologically could index alertness or engagement, whereas weaker or blunted activation might be construed as disengagement or loss of motivation. There are important sex differences in acute stress responses. First, there are reliable sex differences in resting cardiovascular system functioning.
For example, women exhibit higher basal heart rate at rest while men exhibit higher blood pressure at rest. Differences in resting cardiovascular functioning can influence the interpretation of the reactivity of these parameters. Additionally, there tends to be activation differences between men and women with men showing greater overall changes in peripheral physiological responses Blascovich and Tomaka, Sitting with crossed legs.
Crossing your legs squeezes the large veins in your legs, which may raise the reading slightly. Not supporting your arm. This mistake is very common in doctor's offices, says Dr. Your arm should be totally relaxed so your biceps upper arm muscle isn't contracted. Be sure to position your arm on a chair or counter, so that the blood pressure cuff is level with your heart.
Also, don't clench your fist. Wrapping the cuff over clothing. Depending on the thickness of the fabric, putting a cuff over clothing can boost the reading by quite a bit, the AHA says. Wear a short-sleeved shirt along with easily removable layers, if you're chilly in the doctor's office so the cuff is placed on your bare arm. Using a cuff that's not the correct size. Many people need a large-sized cuff, Dr. Fisher notes. Using one that's too small will be uncomfortable and may elevate your pressure by several points.
Note that models with upper-arm cuffs are more reliable than those that fit on the wrist, says Dr. Engaging in conversation. Chatting during the measurement — or even actively listening — can boost blood pressure.