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Responses to Exercise

Acute responses to

exercise

Acute responses

• Immediate/Short term responses

• Last only for the duration of the training or exercise session and for a short time afterwards (recovery)

Cardiovascular responses

• Increased Heart Rate (HR)

–Resting HR is usually around 60-80bpm

–Increases O2 delivery to working muscles

–Aids removal waste products

–Will increase until point of exhaustion

–Maximum HR (MHR) is the highest heart rate value achieved in an all-out effort to the point of exhaustion

• Increased Stroke Volume (SV)–In untrained individuals at rest 60-80mL per beat–During exercise this can increase to 110-130mL–Females have smaller SV than males–Will increase with exercise intensity but may plateau

until exhaustion

Cardiovascular responses

Cardiovascular responses• Increased Cardiac Output (Q)

–Increases as a result of HR and SV increases

–Delivers O2 to working muscles

–During max exercise 20-25L/min up to 35-40L/min in highly trained individuals

• Increased Blood Pressure (BP)

–Pressure exerted against arterial walls

–Systolic BP: pressure during heart contraction

–Diastolic BP: pressure during heart relaxation

–Normal resting BP is 120/80 during exercise this might increase to 180 or 200/80 or 90

Cardiovascular responses

Cardiovascular responses

• Redistribution of blood flow

–More toward working muscles up to 80-90% compared to 15-20% during rest

–Capillaries and arterioles to the muscles vasodilate

–Capillaries and arterioles to the organs vasoconstrict

Cardiovascular responses

• Increased Arteriovenous Oxygen Difference (AVO2)

–Difference in oxygen concentration between arterial

blood and venous blood

–The amount of oxygen extracted by the working

muscles

–Can increase from 5mL/100mL blood at rest to 15-

18mL during max exercise

Respiratory Responses

• Increased Respiratory Rate (RR)

–From 12 per min up to 35-50 per min

• Increased Tidal Volume

–From 0.5L per breath to 3-5L per breath

• Increased Ventilation

–From 5-6L per min to 130-180L per min

• Increased Oxygen Uptake (VO2)

–Rest 0.25L/min to 2-3.5L/min

–Increases with exercise intensity

–VO2 MAX is the maximum amount of oxygen transported, taken up and used by the body

•Takes into consideration per kg body weight

•Generally lower for females

•Aerobic training can greatly increase VO2 max

Respiratory Responses

Oxygen Deficit

• Oxygen supply does not meet oxygen demand

• Anaerobic pathways used to supply energy

• Transition from rest to exercise or an increase in exercise intensity

Steady State

• Oxygen supply equals oxygen demand

• Aerobic pathways used to supply energy

• Plateau in HR and ventilation

Excess Post-Exercise

Oxygen Consumption• EPOC

• Also referred to as oxygen debt

• Oxygen consumed during recovery period

• Above resting levels

• Role is to:

–Replenish PC stores

–Removal lactic acid and CO2

Muscular Responses

• Increased motor unit and muscle fibre recruitment

• Increased blood flow to muscles

• Increased muscle temperature

• Increased muscle enzyme activity

• Increased oxygen supply and use

• Depleted muscle energy stores

Chronic Adaptations to

Training

• Body’s long term responses of the cardiovascular, respiratory and muscular systems

• Three times per week for at least 6-8 weeks

• Changes can be evident at rest or exercise (sub-max or max)

• Adaptations remain until training ceases (reversibility or detraining)

• Depend on type/method, frequency/duration/intensity of training and individual capacities/genetics

Chronic Adaptations

Aerobic vs Anaerobic

• Min 6 weeks but more effective after 12 weeks

• Changes improve efficiency of O2 delivery to muscles in cardiovascular & respiratory systems

• Can decrease the risk of lifestyle diseases

Aerobic

• Min 6 weeks

• Greatest change in muscular system

• Changes enable greater strength, power & speed

Anaerobic

Aerobic Cardiovascular

Changes• Increase left ventricle size & volume• Increased capillarisation of heart & skeletal muscle

• Increased SV• Decreased resting HR• Decreased HR sub-max exercise

• Increased HR during recovery• Increased Q during max exercise• Decreased BP• Increased AVO2• Increased blood volume & haemoglobin

• Decreased blood cholesterol & triglycerides

Aerobic Respiratory

Changes

• Increased ventilation max exercise

• Increased VO2 max

• Increased LIP

Aerobic Muscular Changes

• Increased oxygen utilisation

• Increased muscular fuel stores

• Increased oxidisation of glucose & fat

• Decreased use anaerobic glycolysis system

• Adaptation muscle fibre type

Anaerobic Changes

• Skeletal and cardiac muscle hypertrophy

• Increased ATP & PC stores

• Increased glycolytic capacity

• Increased strength & size of connective tissues

• Increase in number motor units recruited

• Increase speed of nerve impulse transmission

• Increase speed of muscle contraction