Stress:Living and Performance,

an Endocrine story

Drew Deppen BSc

Are you stressed yet?

“If you only follow guru’s, you’ll be nothing but

average.”Stu McGill Stress Guru’s

Walter Cannon Hans Seyle Bruce McEwen Robert Sapolsky – Why Zebra’s don’t get Ulcers Peter Sterling Katrina Borer – Exercise Endocrinology

Stress

11 different definitions

“Stress is a specific response by the body to a stimulus that disturbs or interferes with the ‘normal’ physiological equilibrium of an organism.”

Stressor is anything that causes an organism to experience stress.

The Stress Response

Walter Cannon Homeostasis

Constancy in an open system requires mechanisms that act to maintain this constancy.

Steady-state conditions require that any tendency toward change automatically meets with factors that resist change.

The regulating system that determines the homeostatic state consists of a number of cooperating mechanisms acting simultaneously or successively.

Homeostasis does not occur by chance, but is the result of organized self-government

The Stress Response Hans Selye

General Adaptation Syndrome Now called the Stress Response

Injected Rats with ovary extract Peptic ulcers Enlarged adrenals Shrunken immune tissue

Body has a similar set of responses to a broad array of stressors

Sounds counterintuitive to have same physiology when too hot, and too cold Built around the fact that muscles need energy when stressed Chances of you running for food, or from being food are high

If stressors go on for too long, they can make you sick

Types of Stressors

Acute Physical Stress Fight of Flight response

Highly adapted to handle this type Chronic Physical Stress

Drought, famine, parasites, infections Fairly adapted to handle these things

Psychological and Social Stress Western society, traffic jams, depression, anxiety

Fairly recent in evolutionary timeframe Chess players can place metabolic demands on their bodies

equal to high class athletes at peak events

SNS and PSNS

Sympathetic Nervous System 4F’s

Fighting, Flighting, Frighting, and Sexing Adrenals are connected to SNS via a

preganglionic synapse! Stress Response increases SNS tone

Parasympathetic Nervous System Rest and Digest Inhibited with Stress response

Endocrine Review

Hypothalamus Brain control center secreting releasing and

inhibitory hormones, Oxytocin, ADH, Dopamine Pituitary

Releasing ‘trophic’ hormones Adrenals

Glucocorticoids, Mineralcorticoids, Androgens, Estrogens, and Catecholamines

Other endocrine glands as well HPA axis - this is the main ‘axis’

1- Pineal gland 1b - Hypothalamus 2- Pituitary gland 3- Thyroid gland 4- Thymus 5- Adrenal gland 6- Pancreas 7- Ovary 8- Testis

1bEndocrine Anatomy

Glucorticoid functions Metabolism

↑ Protein Degradation ↓ Protein Synthesis ↑ Amino Acids to liver ↓ Amino Acids to muscle ↑ Gluconeogenesis ↑ Glycogen liver synthesis ↑ Lipolysis ↑ Truncal and Facial lipogenesis and fat deposition

Immune ↓ Inflammatory cytokines ↓ Capillary permeability ↓ Phagocytosis ↓ T-lymphocytes

Blood ↑ Vasoconstriction ↑ blood volume ↑ RBC and Leukocyte synthesis

Kidney ↑ GFR ↑ Na retention – blood volume

Brain ↑ ↓ Mood ↑ Senses ↑ Appetite

General Stress Response You get ‘Stressed’

Muscles need energy NOW Glucose, Protein, Fatty Acids

mobilized HR, BP, Respiration increases Vasodilatation in skeletal muscle

and skin Vasoconstriction in kidneys and

GI tract Decrease reproductive stuff

(during physical stress) Sorry boys and girls - ↓ erections and

ovulations Decrease Immunity Secrete Endorphins – POMC

cells Senses Sharpen Cognition actually improves

How did I get out of this one last time?

Acute Physical Stress (Phase 1) Stressor introduced

SNS system activated Anticipation

Even thinking about certain scenarios

Cyclical SNS activity Catecholamines

Positive feedback causing ↑ NE, Epi

Glucagon secreted (insulin inhibited)

Acute Physical Stress (Phase 2)

Hypothalamus activated in minutes CRH, TRH, ADH

Causes the secretion of trophic hormones

HPA axis fast to react CRH, and ADH releases ACTH

which releases glucocorticoids Intra/Intercellular cytokines

released TNF – a, IL-1, IL-4

ADH, PRL, Endorphins, Enkephalins also secreted

Insulin, Estrogen, Testosterone, and GH inhibited during stress After stress GH may increase

Acute Physical Stress (Phase 3)

Nutrient Partitioning Different depending

on type of exercise Mobilize Energy

↑ hepatic glucose production

Lipolysis Proteolysis Gluconeogenesis Glycogenolysis

Energy Mobilisation Non stressful situations

Body will store energy for later times

Stress! ↑ SNS ↓ PSNS (stops energy

storage) Release glucocorticoids, glucagon,

NE/E FFA’s, glycerol released, glycogen

oxidized, GNG Glucocorticoids actually block

energy uptake in muscles and adipocytes Exercising muscle overcomes

this mechisms --? Crazy Energy is shunted from non-

exercising muscle to exercising muscle

Acute Physical Stress (Phase 4) Recovery

PS tone increases and SNS decreases Restores homeostasis, fuel storage, structural repair

Insulin rebound after high intensity followed by a rapid decrease in NE

GH increases along with IGF’s Early and Late Phase recovery may be different

Cellular glucose uptake Adaptation Occurs

Basal Hormonal Conc. changes PS and SNS changes

Smaller NE response to same exercise bouts

Acute Physical Stress

Hormones Secreted CRH ACTH Glucocorticoids Glucagon ADH Prolactin Catecholamines Endorphins IL-1, IL-6, TNF – a

Hormones Inhibited Insulin Testosterone Estrogen GH IGF’s

Immune Response Common misconception that

stress ↓ IR Initially it enhances immunity –

esp innate More inflammatory cells

mobilized, antibodies released in saliva May need to fight infection from

a tiger bite Prolonged stress ↓ IR

Glucocorticoid, NE/E levels start destroying lymphocytes Can be good to get rid of old

cells Chronic stress response can

lead to autoimmunity Constantly ramping up IR may

lead you toward ‘friendly fire’

Psychological Stress Same stress response Body gears up to utilize a huge

amount of energy Never gets to use it Metabolically costly

No tiger to run from when road-raging

Bad deal Metabolic Syndrome Cardiovascular Disease Ulcers Autoimmune Disease Depression Cancer risk not associated!

May be associated with outcomes

Building Blocks for psychological stress Outlets for frustration

Rats shocked with and without block to gnaw on Humans can imagine outlets

Great way to relieve stress is to stress someone else Social Support

Primates may have a decreased response when surrounded by other primates If others are strangers it doesn’t help

Crying on someone’s shoulder physiologically helps! People with spouses live longer

Predictability Rats shocked after a warning have ↓ response Blitzkrieg bombings

London hit every night, suburbs sporadically – who developed greater responses? Control

Rats that can press lever to inhibit a shock then remove level – huge response People afraid of flying but driving is more dangerous – I can control my driving.

Perception of things worsening 2 rats – 1 gets 10 shocks/hour, other 50

Next day both get 25 shocks per hour – stress response is different

Food Consumption

How many people eat more when stressed? CRH ↓ appetite but Glucocoricoids ↑ appetite

Uses leptin secreted from adipocytes to blunt ‘fullness’ Glucocorticoids help mobilize energy, inhibit storage What’s going on? Released at different times

CRH released immediately, glucocorticoids released slowly Also the clearance is similar – CRH fast, Cortisol slow

Prolonged stressor will cause appetite to ↑ Appetite for calorie dense food is preferentially simulated –

ice cream!

Apples and Pears

Apple shaped people prefer to store fat in abdominal area

Pear shaped people prefer to store fat in gluts Abdominal adipocytes are more sensitive to

cortisol in presence of insulin to store fat Waist-hip ration is a more accurate predictor for CVD

and metabolic syndrome than obesity alone FFA’s more easily transported to liver

Vs.

Coping Strategies Exercise

Gets rid of the energy, must be voluntary and regular, aerobic is better for stress reduction

Meditation Any kind of parasympathetic activation activity

done regularly Gain control/predictability

Can be a double edge sword Social support

Both utilizing others when needed and feeling need for others

Religion/spirituality Allows for social support in fairly healthy decision

group Cognitive flexibility

Chose the right coping strategies Study for the test before hand, and talk about how

it doesn’t matter afterwards Conditioning

Sharpen the on and off times Stress yourself and learn to deal with it – make it a

choice 80/20 Rule

80% of stress reduction occurs within first 20% effort You have to decide to make a change

Exercise effects Cardiovascular and

Respiratory Redistribute blood flow,

regular BP Blood clotting in anticipation

of injury Modulate Pain Mediate tissue repair post-

event Engage Immune defenses

post-event Not a ‘true’ homeostatic

mechanism Spontaneous activity in

positive energy balance?

Endocrine support

Sympathoadrenal Catecholamines NE, Epi

Hypothalamo-pituitary-adrenal axis (HPA) CRH, ACTH, Glucocorticoids

Endogenous Opiates Endorphins (POMC cells)

Hydromineral hormones ADH, Aldosterone, Ang II

Acute Physical Stress

Low intensity Exercise (under 50% VO2) Below 50% VO2 max

Oxidative metabolism Type 1 fibers – red (mitochondria)

40 - 85% energy from FFA’s Carb sparing mechanism

100mg/dl glucose in plasma + 100g liver glycogen 85% utilized during normal daily activity 50% used during overnight fast

10 – 20kg of TG’s storage ↓ Insulin slightly

Hexokinase has a high affinity for Glucose even in absence of Insulin Glut -4 transporter tranlocates to membrane with muscle contraction

↑ NE slightly ↓ Glucose

Moderate Intensity Exercise

50-75% VO2 max Mixed metabolic demands

Endogenous and peripheral storage Mixed fiber types IC- IIA

Endogenous lipids and glycogen primarily used (80%) FFA’s used are from abdominal area/upper body ↓ Insulin with a spike after activity ↑ GH after mild duration of activity ↑ Glucocorticoid during and after activity ↑ Lactate ↑ Glucose with a drop after duration ↑ NE during and after activity

High Intensity Exercise >80% VO2 max 25% lipids and 75% Glucose energy

Mostly intracellular glycogen Stimulate PFK and PDH Increases lactate – inhibits lipolysis Excess acetyl Co-A produces acetyl-Carnitine, Coenzyme A Activates Malonyl Co-A – inhibits fat oxidation

ALL are non-insulin mechanisms to utilize carb catabolism Equal amts TG and peripheral adipose tissue

FFA blocked from entering circulation by NE/E White type IIX fibers

Creatine phosphate systems – early fatigue ↑ NE/E ↑ GH ↑ Glucagon ↓ Insulin with rebound spike after activity ↑ IL-6

Stim GH, PRL, CRH, and ADH secretion

Physical Stress

Nutrition during exercise

Carb supplementation ↑ Carb metabolism, ↓ lipolysis

Insulin mediated Stimulates PDH and ACC (makes malonyl CoA)

Inhibits Carnitine Glucose will cause a mild hypoglycemia for 20mins Fructose will not - ↓ insulin response

↓ Fatigue when eaten after 2 hours moderate intensity

Lipid Suppementation ↑ Lipid Oxidation

After several days of adaptation to high fat diet ↑ FFA uptake in muscle

↑ Lipoprotein Lipase Improves endurance in low and moderate intensity exercise

Spares muscle gylcogen and PCr systems Creatine

Good stuff for power movements

Big Picture

Is stress bad? Yes And no

Stress can do our physiology very well when applied under ‘normal’ circumstances When we get endocrine adaptation things can go

well and we can make gains Stress can also be bad in excess and when

we don’t have any way to channel it Like anything else in life

Coping Strategies Exercise

Gets rid of the energy, must be voluntary and regular, aerobic is better for stress reduction

Meditation Any kind of parasympathetic activation activity

done regularly Gain control/predictability

Can be a douple edge sword Social support

Both utilizing others when needed and feeling need for others

Religion/spirituality Allows for social support in fairly healthy decision

group Cognitive flexibility

Chose the right coping stradegie Study for the test before hand, and talk about how

it doesn’t matter afterwards Conditioning

Sharpen the on and off times Stress yourself and learn to deal with it – make it a

choice 80/20 Rule

80% of stress reduction occurs within first 20% effort You have to decide to make a change