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ACUTE RESPONSES TO EXERCISE KEY KNOWLEDGE The mechanisms responsible for the acute responses to exercise in the cardiovascular, respiratory and muscular systems Oxygen uptake at rest, during exercise and during recovery including oxygen deficit, steady state and excess post-exercise oxygen consumption KEY SKILL Participate in physical activities to collect and analyse data relating to the range of acute effects that physical activity has on the cardiovascular, respiratory and muscular systems of the body WHAT ARE ACUTE RESPONSES?? • Only occur for the duration of exercise and recovery. Short Term. • Are dependent on the intensity, duration and type of exercise being undertaken • Involve the respiratory, cardiovascular and muscular systems working together to supply more energy / ATP and oxygen to working muscles and then again to remove any waste products CARDIOVASCULAR SYSTEM Cardiovascular System = circulates blood, nutrients (O2 and glucose) and removes waste (CO2 and Lactate) Left Ventricle pumps blood around body Cardio = Heart Related Vascular = Blood Vessels (Arteries, capillaries and veins) Haemoglobin transports oxygen from the lungs to the rest of the body tissue (and then transports carbon dioxide back from the tissue to the lungs). RESPIRATORY SYSTEM Extracts O2 from the air and removes CO2 from the body. Lungs Alveoli are tiny air sacs that allow for O2 and CO2 exchange with capillaries MUSCULAR SYSTEM Responsible for movement Myoglobin carries oxygen molecules to muscle tissue. Mitochondria are the cells in which aerobic respiration occurs, and oxidation of fats, carbohydrates and proteins occurs in these cells to release ATP. Contractile proteins = Actin and Myosin slide across each other to produce force for muscular contractions. Substrates = chemicals that can be broken down to produce energy Enzymes = Allow for fuels to break down more quickly. Catalyst FOR EACH ACUTE RESPONSE YOU MAY THE FOLLOWING INFO Definition: Type of response: Measure in: Effect of exercise Benefits: Any negative side effects: Rest vs Maximal Exercise: Trained vs Untrained: How it occurs Aerobic or Anaerobic ACUTE RESPONSES Cardio Vascular Respiratory Muscular Stroke Volume Venous Return Ventilation AVO2 Diff Heart Rate Blood Pressure Tidal Volume Temperature Cardiac Output Redistribution of blood flow & Thermoregulation Respiratory Frequency Motor Unit Recruitment Oxygen Uptake Diffusion Energy Substrate Levels Factors affecting VO2 Blood Volume ACUTE RESPONSES OF THE CARDIOVASCULAR SYSTEM : CARDIO Increased Heart Rate Increased Stroke Volume Increased Cardiac Output HEART RATE INCREASED HEART RATE (HR) Contractions of the heart. - Beats per minute Increases oxygenated blood flow to working muscles Your heart rate has a maximum and this can be APPROXIMATELY calculated by following equation MAX HR = 220 - age Trained athletes will have a lower resting heart rate Heart rate increases in anticipation to exercise – Anticipatory rise INCREASED STROKE VOLUME (SV) Stroke volume is the amount of blood ejected from the heart with each contraction. Stroke volume increases with exercise but only u pto 40-60% of maximum intensity of exercise. Then it plateaus. Untrained individual SV @ rest =60-80mL and @ exercise =80-110mL Trained individual SV @rest = 80-110mL and @ exercise = 160-200mL Question – Does this help you understand why a trained person has a lower resting HR? Males will have generally higher stroke volumes due to their increased heart size. INCREASED CARDIAC OUTPUT (Q) Cardiac Output (Q) is the amount of blood ejected by the heart each minute. It is calculated by multiplying heart rate and stroke v olume Q = HR x SV So that more blood can be ejected out of the heart per minute and therefore more oxygen can be delivered to the muscles For average adult @ Rest = 4-6 Litres per minute @ Exercise = 20-25L For trained athlete this can get up to 35-40 L per minute YOUR TURN! Jim is 32 years old. He has a resting HR of 72. His resting stroke volume is 68mL. . Jim goes for a run at about 50% of maximum and his HR increases to 146 and his stroke volume increases to 98mL. Calculate his resting Cardiac output Q Calculate his Q at exercise YOUR TURN What is meant by the term “acute responses to exercise? Define what is meant by the term heart, stroke volume and cardiac output. How can I calculate my maximum heart rate? Why do females have smaller stroke volumes that males? Describe how HR, SV and Q change with increasing intensity. How do they interrelate? ACUTE RESPONSES OF THE CARDIOVASCULAR SYSTEM : VASCULAR Increased Venous Return Increased Blood Pressure Redistribution of blood flow Decreased Blood Volume Increased Oxygen Uptake INCREASED VENOUS RETURN The amount of blood that is returned back to the heart via the veins More blood delivered back to the heart to reoxygenate Muscle Pump Respiratory Pump Venoconstriction (constriction of the veins) INCREASED BLOOD PRESSURE Blood pressure is the pressure exerted by the blood against the walls of the arteries. Systolic blood pressure – is the blood pressure recorded as blood is ejected during contraction phase of the heart cycle. Will be the higher of the 2 values Diastolic blood pressure – is the blood pressure recorded during the relaxation phase of the heart cycle. Will always have a lower value. More blood is being pumped out per beat/minute and therefore it causes an increase in pressure A normal blood pressure is 120 over 80. During dynamic whole body exercise e.g running cycling blood is pumped more forcefully and quickly out of the heart, this increases systolic blood pressure but diastolic blood pressure barely changes. In resistance type of exercise such as lifting weights there is an increase in both systolic and diastolic blood pressure REDISTRIBUTION OF BLOOD FLOW TO WORKING MUSCLES The redirection of blood away from areas where it is not needed (e.g. spleen, kidneys) to areas where it is (e.g. working muscles) Our blood vessels can expand and increase their internal diameter to allow more blood to be pumped through to muscles. This is called VASODILATION Our blood vessels can constrict to allow less blood through. This is called VASOCONSTRICTION @ Rest 15-20% goes to working muscles. 75-80% to vital organs. @ Exercise 80-90% to working muscles. 10-20% to vital organs. DECREASED BLOOD VOLUME The amount of volume of blood decreases As a consequence of sweating Caused by a decrease in plasma volume due to sweating. Depends on the intensity, duration and environmental factors INCREASED OXYGEN UPTAKE Oxygen uptake (VO2) is the amount of oxygen transported to, taken up by and used by the body for energy production. Reaches a MAXIMUM OXYGEN UPTAKE (VO2 max). Usually occurs around 2-3.5L. When exercise begins oxygen uptake increases as the working muscles use it made possible by the responses by the cardiovascular and respiratory systems. It increases linearly. @ Rest 0.25L per minute FACTORS AFFECTING MAXIMUM OXYGEN UPTAKE Body Size Age Gender Genetics Training Status BODY SIZE A larger heavier person requires more oxygen than a smaller person. Therefore VO2 max is expressed relative to body size in mL/kg/min so it can be compared. GENDER Females tend to have lower oxygen uptake than males of a similar age and athleticism. For untrained individuals can be as great as 20-25% less. Why? Females tend to have a higher amount of body fat and lower muscle mass. Body fat doesn’t use oxygen. Females have lower blood volumes and lower levels of red blood cells and haemoglobin.Therefore less oxygen carrying capacity Females typically have smaller lung size and volume. GENETICS Aerobic capability is largely genetically determined. Up to 25-50% of variance. Training can still largely improve VO2 max. AGE Peaks around late adolescence and early adulthood and then declines after the age of 25. Declines around 10% per decade. Training and being physically active can reduce the decline. TRAINING STATUS (AEROBIC OR CARDIOVASCULAR FITNESS LEVEL) Aerobic training can substantially increase VO2 max. Average VO2 max for untrained adult male 20-29 is 43-52 mL/kg/min. Average VO2 max for untrained adult female 20-29 is 33-42 mL/kg/min. Trained endurance athlete can be up to 50-75 mL/kg/min. Refer to table 3.1. Why does a swimmer have a higher VO2 max than a weight lifter of the same sex and age? http://content.jacplus.com.au/secure/FileViewer?resourceId=136179&cat egory=eLesson&pk=fb5d71007f342bca YOUR TURN Why is VO2 max expressed relative to bodyweight. List and briefly summarize the factors that can affect VO2 max in a table Have a look at the table on pages 102-103 and explain why nordic skiiers have a much higher VO2 max than a weightlifter? ACUTE RESPONSES OF THE RESPIRATORY SYSTEM : Increased respiratory frequency Increased Tidal Volume Increased Ventilation Diffusion INCREASED RESPIRATORY FREQUENCY (BREATHING RATE) Respiratory frequency or breathing rate is the amount of breaths taken per minute. Usually around 12 breaths per minute @ rest. Up to around a maximum of 35-50 during exercise. INCREASED TIDAL VOLUME Tidal volume is the depth of your breathing. Increases from 0.5L per breath at rest to a max of 3-5L per breath. INCREASED VENTILATION Ventilation is the amount of air inspired or expired per minute by the lungs. Tidal volume x Respiratory Rate = Ventilation (TV x RF = V) Increased volume of O2 in lungs => diffused to blood to be transported to working muscles. To increase the volume of oxygen in the lungs that can be diffused into the blood and transported to the working muscles. Greatest increase from RF as TV plateaus @ Rest = 5-6L per minute @ Maximal Exercise = 130-180L or beyond Your Turn! Calculate the Ventilation of an individual who has respiratory rate of 15 breaths per minute and a tidal volume of 0.5L? INCREASED DIFFUSION The movement of oxygen and carbon dioxide to an area of high concentration to an area of low concentration. Occurs in the alveoli of the lungs and the muscle capillaries Gas exchange occurs at the lungs between the alveoli and the cappilaries Gas exchange occurs in the muscle between the muscle tissue and the capillaries. Refer to diagram During exercise diffusion increases to make more O2 available and to get rid of more CO2. ACUTE RESPONSES OF THE MUSCULAR SYSTEM AVO2 Diff Increased Temperature Increased Motor Unit Recruitment Decreased Energy Substrate Levels INCREASED ARTERIOVENOUS DIFFERENCE (A-VO2 DIFF) a-VO2 diff is a measure of the difference in the concentration of oxygen in the arterial blood (arteries and venous blood (veins). To increase the amount of oxygen that is delivered and used by the working muscles to produce energy aerobically. @ Rest arteries usually contain around 20mL of oxygen per 100mL of blood and the veins contain 15mL of oxygen per 100mL of blood. Therefore the a-V02 diff is 20-15 = 5mL per 100mL During exercise will the a-VO2 diff increase or decrease. Why? INCREASED MUSCLE UNIT RECRUITMENT Increased motor neuron firing and the muscle fibres it stimulates More motor units recruited = Greater force! INCREASED TEMPERATURE A change in the internal temperature of the body Mechanisms work to prevent an increase in core body temperature. SWEAT DECREASED ENERGY SUBSTRATE LEVELS The chemicals that are required to resynthesis ATP decrease PC, glycogen, triglycerides •Oxygen Deficit – occurs when oxygen supply lags behind oxygen demands – typically at the start of exercise and when exercise intensities rapidly increase mainly anaerobic energy systems •Steady State – occurs when oxygen supply meets oxygen demand – largely aerobic energy system •Oxygen Debt = EPOC (Excess Post – exercise Oxygen Consumption) – occurs during recovery whilst oxygen levels remain above resting levels – largely aerobic energy system ROBERT MALPELI - BALWYN HIGH SCHOOL 2010 OXYGEN UPTAKE FROM REST • At rest the body is easily able to take in the required oxygen. • As exercise begins, oxygen demand increases and the body is unable to meet this demand. • During this period of oxygen deficit, ATP is produced anaerobically. During steady state, the oxygen supply is equal to demand and ATP is produced aerobically. • At the completion of the exercise, excess oxygen is taken in to enable the body to return to pre-exercise levels. EPOC – It’s sometimes good to extend this via an active recovery ROBERT MALPELI - BALWYN HIGH SCHOOL 2010
