Exercise Physiology Lecture 005 PDF

DPT-413 Exercise Physiology course Exercise Physiology Monira I. Aldhahi Week 5th Dr. Monira Aldhahi- -2024 All Rights Reserved Copyright ...

DPT-413 Exercise Physiology course Exercise Physiology Monira I. Aldhahi Week 5th Dr. Monira Aldhahi- -2024 All Rights Reserved Copyright  Objectives of this class Understand the lactate buffering system Identify the gender related difference in Anaerobic Exercise Characteristics Explain the laboratory and field assessment techniques used to obtain information on aerobic metabolism during exercise. Explain the major variables used to describe the aerobic metabolic response to exercise Dr. Monira Aldhahi- Copyright -2024 All Rights Reserved The lactic acid myth armament  History The Myth originated by Otto Meyerhoff and Archibald V. Hill. They concluded that anaerobic metabolism led to the production of lactic acid which was responsible for the acidosis in the cell and the resultant muscle fatigue. Aaarabic one lactic acidosis ms metabolism qq.it iao fatigue  Since the 1970s, a 'lactate revolution' has occurred… acid tetfbtisn Y.fi ffionaacidosis oms fatigue Dr. Brooks and other colleagues have also shown that the lactate o part of lactic acid can actually be a fuelt for muscles and the heart and that the acid part of lactic acid is not the cause of fatigue. la tepart fuel acid part fatigue  Friend-Than-Foe FI it is actually these H+ ions and not the lactate that lower the pH of tissue which interferes with muscle action. YAa simultaneously activating pain receptors this issue normally resolves itself within 30 to 60 minutes following the cessation of an exercise bout 1 PH 2 Tmsaction 3 Painreceptors  Hydrogen Ion Production During Exercise I Acidosis results from an accumulation of acids or a loss of bases. Alkalosis results from a loss of acids or an accumulation of bases. Ref. Chapter 11: Acid-Base Balance during Exercise by power. Pg.258  Hydrogen Ion Production During Exercise Three important contributors to exercise-induced muscle acidosis: 1- Exercise-induced production of carbon dioxide and carbonic acid in the working skeletal muscles 2- Exercise-induced production of lactic acid in the working muscle 3-Exercise-induced ATP breakdown in the working muscles. For example, the breakdown of ATP results in the following reaction: Ref. Chapter 11: Acid-Base Balance during Exercise by power. Pg.258-259  Pyruvate and H+ ions The body combines the excess pyruvate with these H+ ions to form lactic acid (L– and H+), which can both be removed from the cells and placed into the blood. In other words, the formation of these compounds enables the muscle to continue working longer than it ordinarily is capable of doing.  Buffer system sodium bicarbonate Carbonic acid is a much weaker acid than LA and can be dissociated into Carbonic acid H2CO3 =H2O + CO2 (H2CO3) Ref: CHAPTER 3 Anaerobic Metabolism During Exercise by Plowman. Pg.73 Lactate Clearance monocarboxylate transporters (MCTs) Ref: CHAP TER 3 Anaerobic Metabolism During Exercise by Plowman. Pg. 61-61  Lactate is a Viable Fuel Lactate can be converted back to pyruvate which in turn can be reconverted back to glucose. This reversible process plays a significant role in energy production, carbohydrate preservation and replenishment.  Delayed onset muscle soreness (DOMS) The DOMS experienced over subsequent hours to days has nothing to do with this metabolic by-product, but is believed to be more aligned with microtrauma occurring within the muscle.  Male versus Female Anaerobic Exercise Characteristics The anaerobic characteristics of females are generally lower than are those of males in the young and middle-aged adult years 1. The Availability and Utilization of ATP-PC Neither the local resting stores of ATP per kilogram of muscle nor the utilization of ATP-PC during exercise varies between the sexes In terms of total energy available from these phosphagen sources, males will have more than females because of muscle mass differences. Ref: CHAPTER 3 Anaerobic Metabolism During Exercise by Plowman. Pg.73 2. The Accumulation of Lactate Resting levels of lactate are the same for males and females. absolute workload at which the lactate thresholds occur is higher for males than females. at any given absolute workload that is still submaximal, females have a higher lactate value than do males. Consequently, the workload is more stressful for females and requires a greater anaerobic contribution at a given relative workload above LT, lactate concentrations are equal for both sexes 3. Mechanical Power and Capacity In average males produce higher absolute work output than do females. Data available from the WAnT show that values for peak power for women are approximately 65% of values for men if expressed in watts The peak power of women (in watts per kilogram of body weight) is very similar to the mean power of men. The fatigue index does not show a significant sex difference, indicating that both sexes tire at the same rate.  Anaerobic Exercise Characteristics of Older Adults 1. The Availability and Utilization of ATP- PC Local resting stores of ATP-PC are reduced Results from the Margaria-Kalamen one Stair Climb test have shown a ↓ in ATP- PC power of as much as 45% A reduction in ATP-PC capacity of 32% from youth to old age  Anaerobic Exercise Characteristics of Older Adults 2. The Accumulation of Lactate – On the average, resting levels of blood lactate are remarkably consistent across the entire age span, varying only from 1 to 2 mmol·L−1. – Lactate values during the same absolute submaximal work tend to be higher in individuals over the age of 50 – When younger and older individuals work at the same relative workload (% lactate concentrations are ↓ in older people than in the young, WHY?  Anaerobic Exercise Characteristics of Older Adults 2. The Accumulation of Lactate Older males have an overall lower production than younger males during 60 seconds of maximal static contraction enzyme lactate dehydrogenase a smaller ratio of Physiological muscle mass to blood Mechanism volume slower diffusion of lactic acid out of active muscle fibers and into a smaller ratio of the bloodstream capillary to muscle fiber  Anaerobic Exercise Characteristics of Older Adults 3. Mechanical Power and Capacity The average peak power value obtained on the Margaria-Kalamen Stair Climb test declines from 20 to 70 years of age a decline in maximal anaerobic power approximately 10.3% per decade from 20 to 88 years in males.  Aerobic Metabolism during Exercise The primary goal of measuring aerobic metabolism:  to quantify how much energy is needed to complete a given activity. mom  Rationale for the Fitness Assessment  Establish a baseline  Aid in program design  Establish realistic and prudent goals mama  Evaluate changes and appropriateness of program  Further diagnosis  Describe pathology  Understand patient limitations Measurement of Aerobic Metabolism Aerobic metabolism can be measured by: 1. Direct calorimetry 2. Indirect open-circuit spirometry In exercise physiology, open-circuit indirect spirometry, is typically used.  Calorimetry The term calorimetry is derived from the word calorie, the basic unit of heat energy. Calorimetry is the measurement of heat energy liberated or absorbed in metabolic processes. – Direct calorimetry actually measures heat production. – This measurement requires the use of specially constructed chambers  Indirect Spirometry Spirometry is an indirect calorimetry method for estimating heat production in which expired air is measured and analyzed for the amount of oxygen consumed and carbon dioxide produced. It is also the direct measurement of air breathed.  Indirect Spirometry 1. In a closed system: the subject breathes ⇢ a sealed container filled with gas of a designated composition (often 99.9% O2). – Expired CO2 is usually absorbed by a chemical such as soda lime. – The rate of utilization of the available O2 is then determined.  Indirect Spirometry 2. In open-circuit spirometry: the subject inhales room or outdoor air and exhales into the same surroundings. A sample of the expired air is analyzed for oxygen and carbon dioxide content. mmol  Indirect Spirometry Tomas In situations involving anaerobic energy production, the actual energy cost of the exercise will be underestimated using open circuit, because the linear relationship no longer exists.  Open Circuit Indirect Spirometry The most popular exercise-testing modalities in the laboratory are the motor-driven treadmill and the cycle ergometer. Measurements can be performed with the subject at rest, during submaximal exercise, or at maximal levels of exertion.  Aerobic Exercise Responses Oxygen Consumption and Carbon Dioxide Production see  Aerobic Exercise Responses Oxygen consumption is the variable of primary interest, given its direct relationship with ATP. Determining the amount of CO2 produced is also important because that measure enables a determination about fuel utilization and caloric expenditure.  VO2 and VCO2 VO2= the amount of oxygen inspired minus the amount of oxygen expired. – it is commonly labeled as the volume of oxygen consumed. carbon dioxide produced (Vco2) is technically the amount of carbon dioxide generated during metabolism, primarily from aerobic cellular respiration. – is commonly described as the volume of carbon dioxide produced.  Short-Term, Light- to Moderate-Intensity Submaximal Exercise VO2⇢ level off and remain relatively constant (Figure 1A). This condition is known ???? The time required to achieve steady state varies from 1 to 3 minutes in youths and young adults at low and moderate levels of intensity The time to achieve steady state increases with ⇡ intensity exercise. Figure 1 The time to achieve steady state is longer in older untrained adults.  Long-Term, Moderate to Heavy Submaximal Exercise Oxygen Drift A situation that occurs in submaximal activity of long duration, or above 70% VO2Max or in hot and humid conditions where the oxygen consumption increases, despite the fact that the oxygen requirement of the activity has not changed.  Long-Term, Moderate to Heavy Submaximal Exercise The oxygen consumption increases (drifts upward), why?! – rising blood levels of catecholamine hormones – lactate accumulation (if the percentage of VO2MAX is high enough) – shifting substrate utilization – increased cost of ventilation – increased body temperature  Incremental Aerobic Exercise to Maximum Table :Aerobic Metabolic Responses during an Incremental Treadmill Test (Modified Balke Protocol) VO2 max is the highest amount of oxygen an individual can take in, transport and utilize to produce ATP aerobically while breathing air during heavy exercise.  Incremental Aerobic Exercise to Maximum Typically, the goal is for a maximal test to last 8–12 minutes. healthy individuals, the duration may be between 7 and 26 minutes for the cycle ergometer and between 5 and 26 minutes for the treadmill depending on stage length and treadmill grade with shorter tests requiring a sufficient warm- up.  Incremental Aerobic Exercise to Maximum When a ramp protocol is used, the rectilinear increase in VO2 obtained The rectilinear increase in VO2 obtained during an incremental test can be generalized to all healthy individuals, both male and female, young and old, and those who are high and low in fitness.  Incremental Aerobic Exercise to Maximum ventilation (VE), VO2, and VCO2 values all increase as a result of the increasing demands or and production of energy. For this particular individual, the volume of expired air (VE) rose from 25.21 L/min at minute to 139.04 L/min at minute 28. This demonstrates the reserve capacity in the ventilatory system. Oxygen consumption ⇡ from slightly over 1 L/min (or almost 17 mL·kg−1·min−1) to 5 L/min at maximum.  Respiratory Quotient/Respiratory Exchange Ratio Respiratory Exchange Ratio (RER) = Ratio of the volume of CO2 produced divided by the volume of O2 consumed in the body as a whole. Respiratory Quotient (RQ) = Ratio of the amount of carbon dioxide produced divided by the amount of oxygen consumed at cellular level. For carbohydrates: 1 For fat: 0.71 For protein: 0.8 branched-chain amino acids are used, the RQ would be lower: =.74  Activity 2 ( 5 min) 1 Dr. Monira Aldhahi- -2022 All Rights Reserved Copyright  Static and Dynamic Resistance Exercise Physiological responses to static exercise are generally described in relation to the percentage of maximal voluntary contraction (MVC) at which they take place. static contractions below 15–25% MVC Static and Dynamic Resistance Exercise At the cessation of static exercise, when blood flow is fully restored, a sudden increase in oxygen consumption occurs before the slow, gradual decline of the typical EPOC curve begins. The primary source of energy for dynamic resistance activity such as weightlifting or wrestling is anaerobic. Static and Dynamic Resistance Exercise Dynamic resistance activity has an aerobic component as well. The more the repetitions and the longer the duration of the sets in a weight- lifting workout, the greater is the aerobic contribution. Aerobic Exercise Response  Reference 1.Exercise Physiology for Health, Fitness, and Performance by Sharon A.Plowman and Dr. Denise L. Smith PhD 3rd ed (Ch 4) Pg 92-101 2.Exercise Physiology: Theory and Application to Fitness and Performance by Scott Powers and Edward Howley (Ch2) pg. 67- 69; Pg. 83-86