Kine 442 Exercise Physiology Week 14 Lecture 1 PDF

KINE 442 – Exercise Physiology Week 14 Lecture 1 – Environmental Conditions and the Atmosphere Terminology ↓ Total Pressure = ↓ partial...

KINE 442 – Exercise Physiology Week 14 Lecture 1 – Environmental Conditions and the Atmosphere Terminology ↓ Total Pressure = ↓ partial pressure Atmospheric/Barometric pressure: pressure exerted by the air above you (depends on altitude) different elevations Air Temperature: current temperature of the air in the surrounding area (depends on longitude, latitude, weather, season, altitude) Air Saturation/relative humidity: % of water vapor held in the air (as above) Sea level atmospheric conditions: standardized or reference ambient conditions of pressure and temperature: Barometric pressure of sea level, or 760 mm Hg (referred to as normobaric) Air temperature of 15 degrees Celsius ↑ altitude = ↑ fluid needs Copyright © 2016 Wolters Kluwer All Rights Reserved Standard Atmosphere of Earth - Loading… ~ 04. Nitrogen balances everything Copyright © 2016 Wolters Kluwer All Rights Reserved Physical zones of the atmosphere Troposphere: surface of earth to 26-48,000 feet (variations due to location on earth; thinner at poles) Contains most weather patterns 80% of atmospheric mass Tropopause: up to 164,000 feet; transition to stratosphere; 99% atmosphere mass is below here Stratosphere: above the troposphere to about 32 miles Stratopause: boundary before mesosphere Mesosphere: between 30 and 50 miles in altitude Mesopause: boundary before thermosphere Thermosphere: all atmosphere above mesophere; where temperature increases continuously with altitude Copyright © 2016 Wolters Kluwer All Rights Reserved Physical Zones of Atmosphere and Temperature Loading… Copyright © 2016 Wolters Kluwer All Rights Reserved  KINE 442 – Exercise Physiology Week 14 Lecture 1.2 – Altitude and Pressure  Altitude Hypobaric Pressure: pressure below normal barometric pressure (e.g. below 760 mm Hg) ↓ pressure into arterial blood Hyperbaric Pressure: above normal barometric pressure; deep hyperbaric chambers with high oxygen content often used to seavingtreat decompression sickness or carbon monoxide poisoning Hydrostatic Pressure: pressure exerted by fluid; for example, pressure exerted by water above a scuba diver Lapse Rate: reduction in air temperature with increased altitude, approximately 2 degrees Celsius every 1000 feet to 35,000 feet Troposphere Copyright © 2016 Wolters Kluwer All Rights Reserved  Scientific Tenets for Physical Environment D Dalton’s Law: “the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the gases of the mixture” Potal P P2 if P &= ,P ↓ Ped + + : , Boyle’s Law: “the pressure and volume of a gas have an inverse relationship, when ↑P temperature is held constant” NV = Charles’ Law: “the volume of an ideal gas at constant pressure is directly proportional to the absolute temperature” V IT) = Henry’s Law: “At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.” OT = P, + P2 Copyright © 2016 Wolters Kluwer All Rights Reserved Barometric Pressure Decreases as Altitude Increases Copyright © 2016 Wolters Kluwer All Rights Reserved Physiological Zones of Atmosphere and Performance build up pressure in ears as body chang a adjuststo Copyright © 2016 Wolters Kluwer All Rights Reserved Altitude Around the Globe Loading… Copyright © 2016 Wolters Kluwer All Rights Reserved  KINE 442 – Exercise Physiology Week 14 Lecture 1.3 – Altitude Stress and Hypoxia  Altitudes at which aerobic performance declines 700 m (2300 ft): declines begin 1524 m (5000 ft): declines become more obvious 2200 m (7217 ft): declines become significant Impaired oxygen consumption Impaired endurance performance Decline in oxidative metabolism High-altitude winter sports and mountain climbing 2,743m or more Boulder Co. Copyright © 2016 Wolters Kluwer All Rights Reserved  Hypoxia Decrease in barometric pressure at altitude (hypobaric environment) reduces PO2 Low oxygen Percentage of oxygen in air is same, but total pressure including all gases in air (e.g. PO2) decreases Dalton's Law Creates difficulty in body’s ability to obtain oxygen, less efficiency of gas transport Hypoxia: Diminished delivery of oxygen to target tissues Hypemic hypoxia: reduction in the oxygen carrying capacity of the blood Can't carry as much oxygen per blood Stagnant hypoxia: systemic / regional change in blood flow ↳ Low blood flow creates this Histotoxic hypoxia: inability of the cell to use oxygen for metabolism Hypotoxic hypoxia: deficiency in alveolar oxygenation Copyright © 2016 Wolters Kluwer All Rights Reserved Four Physical and Physiological Levels of Hypoxia Too much of another gas Tissue Copyright © 2016 Wolters Kluwer All Rights Reserved Altitude and Blood Oxygen Saturation O O O Copyright © 2016 Wolters Kluwer All Rights Reserved Other Challenges with Altitude Increased cold with increased altitude Dehydration induced by cold (which has lower water vapor than warm air, increases loss of water - particularly when paired with physical exertion) less humid Increased solar radiation (decreased distance and thinner atmosphere above individual) – vitamin D production, sunburn, DNA damage, skin cancer Copyright © 2016 Wolters Kluwer All Rights Reserved  KINE 442 – Exercise Physiology Week 14 Lecture 1.4 – Cardiovascular and Respiratory Responses to Altitude Cardiovascular Responses to Altitude is a stressor = stress response ↑ HR Increased resting heart rate (response to low PO2) to bic NSV compensate for decreased stroke volume ↓ POz Decreased stroke volume and heart rate during max exercise, creating lower cardiac output and oxygen consumption and decreasing endurance performance Increased blood pressure want blood to flow faster ↓ SV = Purination altitude induced urination ↓ plasma = ↑ blood Copyright © 2016 Wolters Kluwer All Rights Reserved Other Physiological Responses to Altitude Decreased maximal oxygen consumption Declines start at about 2,200 m Decrements of 2-15% maximal oxygen consumption Oxygen transport decreased (lower hemoglobin saturation with oxygen) ↑ RBC Increased in hemoglobin & hematocrit blood concentrations Increased pulmonary ventilation (response to low PO2) Pulmonary diffusion maintained Increased catecholamines estress response Increased blood lactate concentrations Anaerobic used more Copyright © 2016 Wolters Kluwer All Rights Reserved Pulmonary Ventilation Responses to Altitutde Changes seen above 10,000 ft Breath deeper higher + rate At rest, increase in tidal volume (depth breathing) With exercise: tidal volume and breathing rate increase Maximal exercise: ventilation similar to sea level – may represent upper limit to pulmonary ventilation during maximal exercise Body also becomes more alkaline (respiratory alkalosis) as increased ventilation causes loss of CO2. Oxyhemoglobin curve shifts to left to compensate. With time, kidney can compensate by excreting bicarbonate, an acid buffer. Adaptations can occur over time to improves responses to altitude. as you aclemate Copyright © 2016 Wolters Kluwer All Rights Reserved Responses of pulmonary ventilation at rest to PO2 Copyright © 2016 Wolters Kluwer All Rights Reserved Hemoglobin and Hematocrit Responses to Altitude Increase in hemoglobin and hematocrit due to: Acute: dehydration Chronic (3 weeks or more): increase in red blood cell production on -preserve causes > - Alkaleses Copyright © 2016 Wolters Kluwer All Rights Reserved  KINE 442 – Exercise Physiology Week 14 Lecture 1.5 – Metabolic and Performance Responses to Altitude Metabolic Responses to Altitutde Increased reliance on anaerobic glycolysis at submaximal workloads Not delivering oxygen well as Increased blood lactate Increased reliance on carbohydrate metabolism resulting in higher blood lactate due to catecholamine (epinephrine) promoting glycogen use in metabolism At moderate altitudes, acclimatized individuals more likely to rely on lipid metabolism during submaximal exercise than individuals who are not acclimatized Copyright © 2016 Wolters Kluwer All Rights Reserved Performance Responses Short-Duration Performance Responses Only aerobic activities affected Effect of altitude itself is likely minimal Preparation, focus, & other psychological factors contribute Long-Duration Performance Responses Speed is dramatically decreased in endurance running events Adaptations to altitude (hemoglobin increases) can improve performance, so many athletes “live high” (to obtain benefits of longer-term adaptations) but “train low” (to ensure that they maintain performance) Altitude tents to sleep Copyright © 2016 Wolters Kluwer All Rights Reserved Running Performances at Different Altitudes Nair resistance helps Short distance Copyright © 2016 Wolters Kluwer All Rights Reserved Altitude Sickness A pathological condition often requiring medical attention Caused by reduction in partial pressure of oxygen Acute mountain sickness Risk of pulmonary edema & high-altitude cerebral edema Treatment: rest, removal from altitude Dehydration may also occur at altitude Acetazolamine helps prevent side effects of altitude Copyright © 2016 Wolters Kluwer All Rights Reserved  Acclimatization/Acclimation Both acclimatization (adapting to natural environment) and acclimation (adapting to artificial environment such as a hypobaric chamber) provide short-term (less than 1 yr) and long-term (over 1 yr) adaptations Short-term (3-6 weeks) increases Pulmonary ventilation, release of EPO for RBC Loading… production, hemoglobin, hematocrit, plasma volume Long-term (≥3 months) increases Mitochondrial & capillary density, pulmonary diffusing capacity, mitochondrial enzymes, respiratory chain enzymes, cardiac output Live high and train low theory: beneficial adaptations without detriments to training/performance Copyright © 2016 Wolters Kluwer All Rights Reserved Theory to Practice Individual who live at moderate altitudes perform better at high altitude, supporting idea of live high, train low Some teams arrive 18-24 hours prior to competition to allow some initial adaptations; others arrive immediately before, compete, and leave to limit altitude exposure and prevent sickness (especially in anaerobic sports where adaptations provide little benefit but sickness would provide detriment) Blood Doping: increasing the number of red blood cells either by transfusion or by the use of erythropoietin (EPO) to boost the production of red blood cells; typically not permitted and of unknown efficacy Copyright © 2016 Wolters Kluwer All Rights Reserved