Week 11 AS Exercise and Psychological Stress PDF

Exercise and psychological stress Dr. Jeremy Walsh KINESIOL 3H03 Asynchronous Lecture Week #11 mcmaster.ca Lecture Outline Review of the Stress Response The Stress Response Homeostasis, Allostasis, an...

Exercise and psychological stress Dr. Jeremy Walsh KINESIOL 3H03 Asynchronous Lecture Week #11 mcmaster.ca Lecture Outline Review of the Stress Response The Stress Response Homeostasis, Allostasis, and Allostatic Load How do we perform stress research? How do we create stress in a lab setting? How do we measure the stress response? What are the effects of exercise on psychological stress? Cross-Stressor Hypothesis Cardiovascular fitness and stress response Learning Objectives At the end of this lecture you should be able to: Describe the physiological effects of stress hormones and how these effects are measured Loading… Interpret the underlying stress response mechanism from research data Critically evaluate evidence for/against the Cross-Stressor Adaptation Hypothesis Responses to Stress Stress Response: How the body reacts when encountering a real, perceived or expected threat (Lupin et al, 2009) Involves both psychological and physiological elements Amygdala = primary subcortical brain structure responsible for initiating the stress response  Homeostasis and Allostasis Homeostasis: The ability to balance/stabilize one’s internal Loading… environment despite changes to the external environment Narrow range for optimal function  Homeostasis and Allostasis Allostasis: Achieving stability through change Balancing essential coping/adaptation systems depending on a variety of factors (e.g., time of day) Can achieve homeostasis through allostasis  Allostatic Load Allostatic Load = the cost of this adaptation/ coping Applies to stress ◦ Overwork SAM or HPA Under chronic stress (unrelenting) ◦ Neither axis turns off after stress is removed ◦ Not adequately responding to the stressor overworks other systems  Allostatic Load Wear and tear on the brain and body E.g., chronic elevations in blood pressure, heart rate, glucose metabolism, cortisol May lead to decreased immune function, memory loss, mental health disorders  Allostasis & Allostatic Load Goal of a physiological systems: ◦ Maintain homeostasis!! Disruption to homeostasis requires a physiological response… Physiological response = allostasis ‘Cost’ of the response = allostatic load ◦ The bigger the disruption… the bigger the allostatic load Cognitive-Transactional Model of Stress Primary Appraisal “Does this stressor pose a threat?” Re- Physical appraisal Stressor Secondary Appraisal “Can I handle this threat?” Evaluating resources or coping strategies to deal w/ threat Psychological Stressor Novelty Unpredictability Threat to ego Sense of control Physiological Responses to Stress “Fight or Flight Response” SAM Axis HPA Axis (Sympathetic Adrenal Medullary Axis) (Hypothalamic Pituitary Adrenocortical Axis) Effects of Epinephrine & Effects of Cortisol Norepinephrine Increased blood glucose Increased blood pressure Loading… (mobilized from liver) Increased heart rate Increased glucose utilization by the brain Increased alertness and arousal Suppressed digestion Decreased digestion / blood flow to splanchnic region Supressed immune function Responds to THREAT or Responds to UNPLEASANT CHALLENGE  Stresso Stress Response Pathways r Cerebral Cortex SAM Axis HPA Axis (Sympathetic Adrenal Medullary Axis) (Hypothalamic Pituitary Adrenocortical Amygdal Axis) a Corticotropin-Releasing Hormone (CRH) Hypothalamus Sympathetic Nervous System Pituitary Gland Adrenocorticotropic Hormone (ACTH) Adrenal Medulla Adrenal Cortex Epinephrine (EPI) Norepinephrine Cortisol (NE) Responds to THREAT or Responds to UNPLEASANT  Physiology in Action β-Blockers! ↓ Sympathetic Parasympathetic ↑ Sympathetic Parasympathetic Drug that blocks action of norepinephrine on β- adrenergic receptors in heart Heart Rate Prevents stress-induced heart rate increases Lecture Outline Review of the Stress Response The Stress Response Homeostasis, Allostasis, and Allostatic Load How do we perform stress research? How do we create stress in a lab setting? How do we measure the stress response? What are the effects of exercise on psychological stress? Cross-Stressor Hypothesis Cardiovascular fitness and stress response How do we create stress in a lab setting? Active Stressors Stroop colour-word test State colour of ink & ignore word Mental arithmetic Subtract 7 from large number for 2 min as quickly as possible Public speech / job interview Passive Stressors Painful, loud, startling stimuli - Watch emotionally negative films/images How do we measure the stress response? Self-Report and Hormones Self-report measures using validated questionnaires Assess magnitude and frequency of perceived stress PRO: can assess stress in large groups CON: cannot assess underlying physiological responses to stress Hormones Measure EPI, NE, and cortisol Blood and saliva Potential issues??? Hate needles Hormones naturally fluctuate throughout the day… Important consideration when conducting research How do we measure the stress response? Cardiovascular Responses ↓ Parasympathetic ↑ Sympathetic Blood pressure Heart Rate Vasoconstriction α1-adrenergic receptor Arter y = Norepinephrine = Epinephrine  Section Summary 1. Stress response impacted by continued appraisal of the Novelty, Unpredictability, Threat to Ego, and Sense of Control of a stressor 2. Increased heart rate, blood pressure due to increased EPI and NE represent SAM activation Increased sympathetic activity & decreased parasympathetic activity 3. Increased cortisol represent HPA activation 4. Variety of stress tasks that can be used in research Active vs. Passive Lecture Outline Review of the Stress Response The Stress Response Homeostasis, Allostasis, and Allostatic Load How do we perform stress research? How do we create stress in a lab setting? How do we measure the stress response? What are the effects of exercise on psychological stress? Cross-Stressor Hypothesis Cardiovascular fitness and stress response Cross-Stressor Adaptation (CSA) Hypothesis Novelty Unpredictability Threat to ego Exposure to a stressor of sufficient Sense of control intensity and/or duration will induce adaptation and decreased sensitivity of stress response system Exercise Psychologica Stressor l Stressor Habituation Stress hormones Reactivity to a stressor is lower… Recovery from a stressor is faster… Re-establish homeostasis faster Lower allostatic load Physiological Adaptation Cross-Stressor Adaptation (CSA) Hypothesis Exposure to a stressor of sufficient intensity and/or duration will induce adaptation and decreased sensitivity of stress response system Habituation Reactivity to a stressor is lower… Recovery from a stressor is faster… Re-establish homeostasis faster Lower allostatic load Exercise and Psychological Stress Cardiorespiratory Fitness Part 1 ‘Fit’ vs. ‘unfit’ men (based on VO2peak test) Stressor = mental arithmetic test Measured blood pressure & heart rate O’Sullivan and Bell (2001) Autonomic Neuroscience. 91; 76–84  Exercise and Psychological Stress Exercise training reduces stress response Part 2 “Unfit” performed 5 wks of exercise training (cycling) 3x/wk @ moderate intensity (60% VO2peak Training increased VO2peak O’Sullivan and Bell (2001) Autonomic Neuroscience. 91; 76–84 Why do we care? The acute stress response is beneficial for survival and responding to a challenging or threatening situation… What are the implications of chronic stress? Risk of heart attack * O’Keefe et al. (2019) Mayo Clin Proc