UNIT 3: AREA OF STUDY 2

Transcription

1 UNIT 3: AREA OF STUDY 2 PHYSIOLOGICAL RESPONSES TO PHYSICAL ACTIVITY TOPIC 1: FOODS, FUELS AND ENERGY SYSTEMS Energy from muscular contraction comes from Adenosine Triphosphate. An acceptable abbreviation is ATP. ATP is stored in the muscle. ATP --> ADP + Pi + energy You have approximately 90 grams. This is good for 2-3 all-out maximal contractions. (2-3 sec.) An activity like the vertical jump would use stored ATP. Once ATP splits and energy is released it becomes ADP (Adenosine Di-phosphate). ATP needs to be regenerated/replenished if exercise is to continue past 2 seconds. Energy from the food we consume is used as fuel(s) by the three energy systems to replenish ATP. QUESTION 12 What is ATP and what does it provide? Solution The School For Excellence 2011 The Essentials Physical Education Book 1 Page 28

2 THE ROLE OF CARBOHYDRATES Carbohydrates are stored as glycogen (Muscle Glycogen or Liver Glycogen). Transported in the blood as glucose. Glycogen is the body s preferred fuel when exercising. Another term used for fuel is substrate. Why is glycogen preferred when exercising at moderate/high intensities? Requires less oxygen to release energy compared to triglycerides (fat). An 80 kg person may have stored: Muscle glycogen 400 grams. Liver Glycogen 100 grams = 500 grams = 2000 calories. 1 hour of steady running = 700 calories. Therefore glycogen would run out at just under 3 hours of continuous steady running. Thus, the importance of Carbohydrate (fuel) Replenishment: What could you use to replenish fuel during the run? Gels and sports drinks are very effective. But the body/stomach can only absorb calories per hour. In hot conditions you burn/use calories at a higher rate but your absorption of calories is even slower. THE ROLE OF FATS Converted into Triglycerides stored in the muscle stored as Adipose tissue. Transported as Free Fatty Acids. Preferred fuel at rest and low intensity exercise as sufficient oxygen is available. This results in a much greater yield of ATP. Not the preferred fuel when exercising at higher intensities as free Fatty Acids are transported quite slowly and a greater amount of oxygen is needed to breakdown them down compared to glycogen. The School For Excellence 2011 The Essentials Physical Education Book 1 Page 29

3 THE ROLE OF PROTEINS Broken down into amino acids and stored in the muscle. Main functions are growth and repair, enzyme production. Not normally used as a fuel source for ATP production. Only used in extreme circumstances. Food Fuels Broken down into? Storage Sites Transported as? Carbohydrates Glycogen Muscle Liver Glucose Fats Triglycerides Muscle Adipose Tissue Free Fatty Acids Protein Amino Acids Muscle At Rest 2/3 Triglycerides & 1/3 Glycogen. THE CONTRIBUTION OF FUELS Exercise preferred fuel = glycogen Why? But if you can metabolise triglycerides at higher exercise intensities (glycogen sparing) this is a distinct advantage to the athlete. Why? Substrate an alternative term for fuel. 1 Fat molecule fully broken down = a yield of 441 ATP. 1 Glucose molecule fully broken down = a yield of 36 ATP. The ranking of carbohydrate Glycemic Index High GI / Low GI. The School For Excellence 2011 The Essentials Physical Education Book 1 Page 30

4 CARBOHYDRATE LOADING Method: CHO intake 3-5 days before major competition. quantity & quality of training. Why? Glycogen stores have super-compensated (over-flowing). Performance enhancing greater fuel stores prolong performance/not faster. Disadvantages could body weight; in water storage with extra glycogen (feel stiff / heavy). QUESTION 13 What is Carbohydrate Loading? Solution GLYCOGEN SPARING QUESTION 14 (a) Describe the graph. (b) What is Glycogen Sparing? The School For Excellence 2011 The Essentials Physical Education Book 1 Page 31

5 HITTING THE WALL QUESTION 15 (a) What does this term refer to? (b) What type of athlete or event might this happen? (c) What is the effect on performance and why? (d) How might an athlete avoid Hitting the Wall? The School For Excellence 2011 The Essentials Physical Education Book 1 Page 32

6 THE ATP-CP ENERGY SYSTEM Fast rate of ATP production & Small yield / capacity Type of activity = Short duration/high Intensity (100 metre sprint) Fuel= PC stored in muscle replenished via passive recovery 30 sec. 70% replenished 3 min. 100% replenished Source of CP red meat, eggs QUESTION 16 What are the benefits of being aerobically fit with regard to the ATP-CP system? Solution QUESTION 17 (a) What is the advantage of this system? (b) What is the disadvantage of this system? The School For Excellence 2011 The Essentials Physical Education Book 1 Page 33

7 THE LACTIC ACID ENERGY SYSTEM Fast rate of ATP production & Small yield (but greater than the ATP-CP system) Type of activity = Duration (up to 75 sec) High Intensity. Video (400 metres). Activated at the start of intense exercise. Fuel = Glycogen. Metabolic fatiguing by-products (H+). Insufficient O 2 pyruvic acid lactic acid. Increasingly important system when intensity increases above 85% HR max (Lactate Inflection Point / Lactate Transition Point LT2). Glucose molecule is not fully broken down = 2 ATP produced. QUESTION 18 What is the major limiting factor of this system? Solution The School For Excellence 2011 The Essentials Physical Education Book 1 Page 34

8 Slow rate of ATP production & Large yield THE AEROBIC ENERGY SYSTEM Type of Activity At rest / low & sub-maximal intensity. from 75 sec when intensity is continuous and of a high intensity. Two major fuels (triglyceride/glycogen). 3 Stages one glucose molecule = fully broken down via: Aerobic Glycolysis (2 ATP). Krebs Cycle (2 ATP). Electron Transport System (32 ATP) = Total = 36 ATP produced. ATP RE-SYNTHESIS Anaerobic Energy Systems Aerobic Energy System Intensity (rate) High Intensity = Fast rate of production Low / sub-maximal = Slow rate of production Duration (yield) Short duration = small yield (amount of ATP) Long Duration = large yield The School For Excellence 2011 The Essentials Physical Education Book 1 Page 35

9 SUMMARY OF THE THREE ENERGY SYSTEMS Characteristic ATP-CP System Lactic Acid System Aerobic System Fuel Source Creatine Phosphate Glycogen Intensity High 95% High 85% of Max HR Glycogen / Triglyceride /Protein Rest / Low / Sub-max 85% max HR Predominant For? (maximal/continuous) 0 10 sec sec 75 sec plus Peak Power 5 sec 15 sec ATP Produced By-Products 0.7 ATP for each CP molecule Pi (inorganic phosphate + ADP 2 ATP for each glucose molecule Lactic Acid = Lactate + Hydrogen Ions ADP 36 ATP = Glycogen 441 ATP= Triglyceride molecule CO2 + H2O + Heat Related Fitness Component Anaerobic Capacity / Power Muscular Strength Muscular Power Agility Dynamic Flexibility Anaerobic Capacity / Power Local Muscular Endurance Muscular Power Agility (with repeated efforts) Aerobic Endurance Local Muscular Endurance Static Flexibility The School For Excellence 2011 The Essentials Physical Education Book 1 Page 36

10 THE ENERGY SYSTEM INTERPLAY Key points to remember: All three energy systems are activated at the start of exercise. The predominant system is determined by the intensity and duration of the exercise. The intensity and duration will also determine the rate and yield of ATP production All three systems are activated at the start of exercise. The predominant system is determined by the Intensity and Duration of the activity. Used in any given exercise activity are: OTHER FACTORS AFFECTING THE PROPORTIONS OF ENERGY SYSTEMS Level of fitness (whether adaptations to training have included enhancement of relevant enzymes which would for example postpone levels of lactate accumulation). Availability of O 2 and food fuels. The School For Excellence 2011 The Essentials Physical Education Book 1 Page 37

11 EXAMPLE Explain interplay of all three systems evident in the training of an athlete as follows: 6 x 15 m sprints every 30 seconds. Solution "all energy systems would be activated at the onset of exercise, the ATP-PC system would be predominant for the first 4 high intensity, short duration sprints; however, since PC stores are being depleted by these sprints, and the recovery time provided is not sufficient to fully replenish PC stores, the lactic acid system would begin to contribute more and more with every sprint. The 5th and 6th sprints would see the lactic acid system become the most predominant in supplying ATP. The aerobic system would be contributing minimally during the sprint periods because they are of such a high intensity, however it would be predominant during the 30 second rest periods as they are passive and of low intensity. The aerobic system during these rest periods would help in supplying oxygen to muscles to help replenish PC and breakdown/oxidise H+." Duration (min:sec) :53 3:55 Intensity (% VO 2 max) % Aerobic The School For Excellence 2011 The Essentials Physical Education Book 1 Page 38

12 QUESTION 19 In reference to the graph: (a) Describe the graph. (b) Explain why the running speed of the athlete would be much faster in the 200 m compared to the 1500 m? (refer to the energy systems) (c) (d) Why is the oxygen deficit relatively the same for all events? Concept of a finite capacity How is it possible that all athletes are able to run at greater than 100% of VO2 max? QUESTION 20 VCAA 2007 Question 8 The study below shows the relative contributions of energy production from the anaerobic and aerobic energy systems. It was found, for each duration of maximal work the subject exhausted their anaerobic energy supply. Fill in the table with the estimated energy release from the aerobic and anaerobic energy systems. Duration (maximal intensity work) seconds Total Energy Release ml / kg Aerobic ml / kg Anaerobic ml / kg Marks Concept of a finite capacity the Anaerobic Energy systems have a limited capacity to produce ATP (limited stores of CP that cannot be replenished until you stop) the LA system is also limited by the accumulation of fatiguing by-products. Extended question have tended to concentrate on The Energy System Interplay (a) (b) Use the data to support/justify the use of the three energy systems in a particular sport. Describe the interplay in a selected sport. (2009 VCAA Surfing competition). The School For Excellence 2011 The Essentials Physical Education Book 1 Page 39

13 AREA OF STUDY 2: PHYSIOLOGICAL REQUIREMENTS OF PHYSICAL ACTIVITY TOPIC 2: THE MECHANISMS RESPONSIBLE FOR THE ACUTE RESPONSES TO EXERCISE To meet the increased energy demands when the body transitions from rest to exercise, there is a combined / coordinated response from our respiratory, cardiovascular and muscular systems. The rapid response from the body to meet these changes in energy demand are the bodies acute responses. RESPIRATORY SYSTEM The School For Excellence 2011 The Essentials Physical Education Book 1 Page 40

14 VE = TV x BF Where: VE = Ventilation (litres of air / minute) TV = Tidal Volume (air / breath) BF = Breathing Frequency The acute response to exercise is linear. As exercise intensity (energy requirements) increase so too does Ventilation. QUESTION 21 Complete the following table Rest Exercise TYPICAL ACUTE RESPONSES VE = TV BF The primary mechanism during exercise is a neural input that likely originates from the same area of the brain that is telling the skeletal muscles to exercise. This would explain the rapid increase and decrease of minute ventilation (VE) with the onset and cessation, of exercise. However, a "fine tuning" of exercise VE is accomplished primarily by the peripheral chemoreceptors, that detect increases in H+, CO 2 and heat. The School For Excellence 2011 The Essentials Physical Education Book 1 Page 41

15 QUESTION 22 Describe the graph. The School For Excellence 2011 The Essentials Physical Education Book 1 Page 42