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Overview of Exercise Metabolism PowerPoint Presentation

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Description : Check out this medical PowerPoint presentation titled "OVERVIEW OF EXERCISE METABOLISM” by GSSI.

This medical PowerPoint presentation talks about exercise metabolism, the series of physiological processes that occur in the body during physical activity to produce energy for muscular contraction. The body uses different metabolic pathways depending on the intensity and duration of the exercise.

During low-intensity exercise, the body primarily uses aerobic metabolism to produce energy. This process involves the use of oxygen to break down carbohydrates, fats, and proteins to produce adenosine triphosphate (ATP), which is the energy currency of the body.

As exercise intensity increases, the body relies more on anaerobic metabolism to produce energy. This process involves the breakdown of carbohydrates without oxygen, producing ATP more quickly but also producing lactic acid, which can cause muscle fatigue.

The bodys metabolism also adapts to long-term exercise training. Regular exercise can increase the number and size of mitochondria in muscle cells, which are the organelles responsible for aerobic metabolism. This can improve the bodys ability to use oxygen and produce energy, allowing for better endurance and fatigue resistance during exercise.

Other factors that affect exercise metabolism include the type of exercise (e.g., endurance vs. strength training), nutrition (e.g., carbohydrate and protein intake), and individual factors such as age, sex, and genetics.

Understanding exercise metabolism is important for athletes, coaches, and healthcare professionals who work with individuals to improve their fitness and performance.

Tags : exercise metabolism, metabolic pathways, Fitness, health and fitness PowerPoint presentation

Published on : Apr 26, 2023 | Views : 391 | Downloads : 5

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Slide 1-

OVERVIEW OF EXERCISE METABOLISM Lecture content provided by GSSI, a division of PepsiCo, Inc. Any opinions or scientific interpretations expressed in this presentation are those of the author and do not necessarily reflect the position or policy of PepsiCo, Inc.
Slide 2-

Lecture Outline Muscle contraction energetics Rest to Exercise transition Metabolic responses during recovery Influence of intensity and duration Estimation of fuel utilization
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Energy for Muscle Contraction Adenosine Triphosphate (ATP) Molecule which provides energy for muscle fibers to contract The amount stored in the muscle is limited Hargreaves, M & Spriet, L. Nat Metab. 2020; https://doi.org/10.1038/s42255-020-0251-4.
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Energy for Muscle Contraction Fuel Sources to Generate ATP for Muscle Contraction PCr (phosphocreatine) Anaerobic Glycolysis Aerobic Metabolism High intensity ~5 s or less High intensity ~30 s – 3 min Lower intensity Long duration Glucose Glucose Fatty Acids Regenerated during recovery Notes: Creatine is made in the body and consumed from meat. The PCr system is also the mechanism through which creatine supplements provide energy for high intensity muscle contraction Glucose is supplied mainly from the breakdown of GLYCOGEN, the storage form of glucose in the muscle and liver Amino acids can enter the aerobic glycolysis system, but their contribution to ATP generation is very small Hargreaves, M & Spriet, L. Nat Metab. 2020; https://doi.org/10.1038/s42255-020-0251-4.
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Energy for Muscle Contraction - Byproducts Anaerobic glycolysis Lactate Aerobic Metabolism CO2 As oxygen is used in the process to convert fuels to ATP, carbon dioxide is produced Respiration increases to remove the excess CO2 from the body Previously thought to cause fatigue and muscle soreness. No longer believed to be the case, may provide an additional fuel source Hargreaves, M & Spriet, L. Nat Metab. 2020; https://doi.org/10.1038/s42255-020-0251-4.
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TRANSITIONS
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Rest to Exercise Transition Imagine a football player is standing on the sideline. On coach’s whistle, he is to begin sprinting. What is happening in the body to ensure the muscle has the fuel to go from rest to quick contractions?
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Rest to Exercise Transition Within the first step muscles must increase their rate of ATP production Anaerobic energy sources (PCr + anaerobic glycolysis) are used first, giving time for the aerobic system to contribute Take Home Message: several energy systems are involved in rest-to-work transitions Measurement of O2 consumption can be used as an index of aerobic ATP production Provides information about aerobic metabolism during exercise VO2 max = maximal oxygen consumption, often used as an indicator of fitness Oxygen deficit = lag in O2 update at the beginning of exercise, indicating the reliance on anaerobic systems Hargreaves, M & Spriet, L. Nat Metab. 2020; https://doi.org/10.1038/s42255-020-0251-4.
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Recovery from Exercise: Metabolic Responses Metabolism (indicated by oxygen uptake) remains elevated for several minutes after exercise The magnitude of elevation depends on the intensity of exercise EPOC = Excess Post-Exercise Oxygen Consumption Why does EPOC occur? Resynthesize PC Replace O2 in muscle & blood Elevated body temperature Convert lactic acid to glucose Elevated epinephrine & norepinephrine Sport Nutrition 3rd Ed. Jeukendrup & Gleeson, Human Kinetics.
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Influence ofIntensity andDuration onEnergy PathwaySelection
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Influence of Duration on Source of ATP PCr PCr Anaerobic glycolysis 1-5 s PCr Anaerobic glycolysis Aerobic Systems* > 1 min ~5-10 s Most sports use a combination of anaerobic and aerobic pathways to produce ATP Sport Nutrition 3rd Ed. Jeukendrup & Gleeson, Human Kinetics. Hargreaves, M & Spriet, L. Nat Metab. 2020; https://doi.org/10.1038/s42255-020-0251-4. *Major pathway, muscle glycogen dominant fuel source Several minutes to hours Aerobic Systems CHO and Fat provide almost all ATP
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Influence of Duration Duration of MAXIMAL Exercise Contribution of Aerobic/Anaerobic Production of ATP During MAXIMAL Exercise as a Function of the Duration of the Event Recreated from: Powers & Howley. McGraw-Hill Education. 2017
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Influence of Duration & Intensity Short-Term Intense Exercise Energy comes primarily from anaerobic pathways Length of the activity determines if PCr or glycolysis is the predominant energy source Transition from PCr to glycolysis is a gradual shift Example 50 m dash or single play in a football game: PCr 400 m dash (~55 s): PCr, glycolysis, and aerobic, with anaerobic glycolysis predominating Powers & Howley. McGraw-Hill Education. 2017
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Influence of Duration & Intensity Prolonged Exercise Energy comes primarily from aerobic metabolism Steady-state oxygen update can be maintained during prolonged low-intensity exercise However, a hot/humid environment or higher intensity increases oxygen consumption over time Reminder Oxygen consumption is an indicator of aerobic metabolism Powers & Howley. McGraw-Hill Education. 2017
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Assessing Metabolism during Exercise
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Incremental Exercise: VO2 Max Incremental exercise = gradually increasing exercise intensity over time As intensity increases, oxygen uptake increases in a linear fashion until VO2 max is reached VO2 max is the “physiological ceiling” for the ability to deliver O2 to contracting muscles Training can result in an increased VO2 max, and sometimes training intensity is set at a %VO2 max Intensity VO2 (L/min) VO2 max Powers & Howley. McGraw-Hill Education. 2017
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Incremental Exercise: VO2 Max VO2 max is influenced by: The maximal ability of the cardiorespiratory system to deliver oxygen to the muscle The muscles ability to take up the oxygen and produce ATP aerobically Genetics “Excellent” VO2 max values for ages 18-25 yo: > 60 mL/kg/min > 56 mL/kg/min VO2 max values of some of the best US male and female endurance athletes Joan Benoit Distance Runner 1984 Olympic Marathon Champion 78.6 mL/kg/min Lance Armstrong Cyclist 84.0 mL/kg/min https://www.topendsports.com/testing/records/vo2max.htm Powers & Howley. McGraw-Hill Education. 2017
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Intermittent Exercise: Lactate Threshold Most of the ATP production in the early part of an incremental exercise test (lower intensities) comes from aerobic sources As intensity increases, blood levels of lactic acid begin to rise While there is debate, it is thought that the rise in lactic acid indicates an increasing reliance on anaerobic metabolism Lactate threshold (LT) = exercise intensity where there is an increase in lactic acid in the blood Intensity Blood lactate concentration LT Powers & Howley. McGraw-Hill Education. 2017
Slide 20-

Intermittent Exercise: Lactate Threshold While the exact cause of the LT is unclear, it may occur due to: Low muscle oxygen Accelerated glycolysis Reduced rate of lactate removal In a practical setting, lactate threshold can be used to set training intensity Intensity Blood lactate concentration LT Powers & Howley. McGraw-Hill Education. 2017
Slide 21-

Intermittent Exercise: Lactate Threshold Lactate is now known NOT to cause fatigue However, the LT test is still utilized Click here to watch a YouTube video by Dr. Laurent Bannock explaining lactate and the utility of VO2 max vs LT testing Intensity Blood lactate concentration LT
Slide 22-

Estimation of Fuel Utilization Respiratory Exchange Ratio (RER) = VCO2/VO2 = Ratio of carbon dioxide produced to oxygen consumed Based on their chemical structures, fat and carbohydrate differ in the amount of O2 used and CO2 produced during oxidation Fat oxidation requires more O2 than carbohydrate Ignores protein, since protein contributes little as a fuel source Determined using a metabolic cart during steady state exercise Powers & Howley. McGraw-Hill Education. 2017
Slide 23-

Estimation of Fuel Utilization Percentage of Carbohydrate and Fat Utilization by RER value (R) Powers & Howley. McGraw-Hill Education. 2017
Slide 24-

Aerobic Metabolism: Influence of Intensity and Duration on Fuel Selection
Slide 25-

Intensity & Fuel Selection Schematic of Energy Sources Based on Exercise Intensity Fat is the primary energy source for low-intensity exercise ( < ~30% VO2 max) Carbohydrate is the primary energy source for high intensity exercise (> 70% VO2 max) Athletes are almost always using a mixture of carbohydrate and fat % Energy from Fuel Source Powers & Howley. McGraw-Hill Education. 2017
Slide 26-

Intensity & Fuel Selection Spriet L and Randell R. Sports Science Exchange. 2020;29(205)1-6
Slide 27-

Intensity & Fuel Selection Schematic of Energy Sources Based on Exercise Intensity MYTH: Individuals exercising to lose weight should work out at a lower intensity, in the “fat burning zone. TRUTH: Weight loss depends on overall calories expended. Exercising at a lower intensity results in lower calorie burn (given the same duration). It is more beneficial to work out at a higher intensity, to get a greater EPOC and use more fat for energy during recovery. % Energy from Fuel Source
Slide 28-

Duration & Fuel Selection At a given intensity, as exercise duration increases there is a gradual shift from carbohydrate utilization to a greater reliance on fat as a fuel source Exercise Time % Energy from Fuel Source Carbohydrate Fat Powers & Howley. McGraw-Hill Education. 2017
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TRAINING
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Impact of Training on Fuel Metabolism for Improved Performance Regular training can improve fatigue resistance and performance, partly through changes in muscle metabolism High Intensity Interval Training (HIIT) Endurance Training Increases capacity for anaerobic energy production Enhances tolerance to metabolic acidosis (increased buffering capacity) Increased VO2 max, leading to greater fatigue resistance Increased skeletal muscle mitochondrial density Increased fat oxidation Increased capacity for carbohydrate oxidation, allowing for maintenance of higher power output Hargreaves, M & Spriet, L. Nat Metab. 2020; https://doi.org/10.1038/s42255-020-0251-4.
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SUMMARY
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Link to Summary Video