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Exercise physiology Exercise physiology Recommended literature: 1) Wilmore, J. H., & Costill, D. L. (1994). Physiology of sport and exercise. Champaign, IL: Human Kinetics. 2) Åstrand, P.-O., Rodahl, K., Dahl. H. A., & Strømme, S. B. (2003). Textbook of Work Physiology: Physiological Bases of Exercise (4th ed.). Champaign, IL: Human Kinetics. 3) Brooks, G. A., Fahey, T. D., & White, T. P. (1995). Exercise physiology: human bioenergetics and its applications (2nd ed.). 4) Mountain View, CA: Mayfield Publishing Company. Sharkey, B. J. (1990). Physiology of fitness. Champaign, IL: Human Kinetics. Exercise => causes the changes in human body A) Acute response to one bout of exercise – e.g. ↑ heart rate (HR), ↑ body temperature (HR) B) Chronic adaptation to repeated bouts of exercise - e.g. ↓ HR at rest and ↓ HR at exercise (same intensity) Muscle activity requires energy. During exercise are energy demands enhanced. - decrease of ATP, increase of ADP Muscle contractile work = transforming chemical energy into kinetic (mechanical) energy Energy metabolism A) Anabolism - creation of reserve (carbohydrate, fat, proteins) B) Catabolism – release of energy (glycolysis, lipolysis) ATP hydrolisis phosphorylation ADP + P + E ATP – adenosine thriphosphate - common energy “currency” ADP – adenosine diphosphate P - phosphate E - energy (e.g. for muscle contraction) Energy metabolism Energy sources 1] Polysaccharides 2] Fats (triglycerides) 3] Proteins simple sugars glucose (glycogen) fatty acids (FFT) and glycerol amino acids Energy metabolism Glucose is the only one that can be broken down anaerobically and aerobically as well. Anaerobic glycolysis blood plasma membrane G G cell plasma G–6-P Glycogen (GG) 2 ATP (G) 3 ATP (GG) pyruvic acid lactic acid Energy metabolism Aerobic glycolysis pyruvic acid (pyruvate) cell plasma mitochondrial membrane mitochondrion Acetyl CoA NADH (nicotinamide adenine dinucleotid) and FADH Citric acid cycle CO2 Energy metabolism oxidative phosphorylation – in mytochondrion (electron transport chain) NADH + O2 + 3ADP 3ATP + NAD + H2O 1 NADH=3 ATP FADH + O2 + 2ADP 2ATP + FAD + H2O 1 FADH=2 ATP Energy metabolism From one molecule G GG Anaerobic glycolysis 2 ATP 3 ATP Aerobic glycolysis 36 ATP 36 ATP Total glycolysis 38 ATP 39 ATP Glycogen reserves are in muscle cells (500 g) and in liver (100 g). - From 1.500 to 2.500 kcal. 1 calorie (cal) is the amount of energy increases the temperature of 1 gram H2O from 14.5ºC to 15.5ºC. Energy metabolism Fat - triglyceride = FFA (free fat acids) + glycerol in subcutaneous tissue (141 000 kcal). Adipose tissue Glucose metabolism triglyceride Hormone- FFA + Glycerol sensitive lipase NADH Beta oxidation Acetyl CoA NADH Citric acid cycle CO2 Energy metabolism anaerobic aerobic Glucose proteins FFA and/or Acetyl CoA lactic acid Citric acid cycle NADH and FADH Electron transport chain plasma membrane Energy metabolism Anaerobic metabolism - only carbohydrate - increases when lack of O2 - lower amount of ATP, but very fast and huge in short time - production of lactic acid Anaerobic metabolism - carbohydrate, fats, proteins - enough of O2 - higher amount of ATP, but slower Note: proteins are not very important sources of energy (5-10%). Amino acids are preferabely used as a building matters for muscles hormones, etc. Energy metabolism ATP hydrolisis phosphorylation ADP + P + E ATP is only the one immediate source of energy for muscles work, etc. Other ways of the creation (phosporylation): ATP + P ATP + AMP ADP + CP(creatine phosphate) ADP + ADP Zones of energy supply Exercise Duration Dominative source of Production intensity (type) maximum submaximal energy of lactic till 15 s freeATP, Small Anaerobic of CP lactic acid 15 – 50 s ATP, CP, anaerobic Maximum glycolysis Short term glycolysis Middle endurance till 10 min Long term endurance aerobic glycolysis latter lipolysis FG FG FG and FGO medium More than free aerobic glycolysis, small Aerobic of lactic acid 10 min fiber type and FGO Anaerobic with and lactic till 120 s Anaerobic aerobicacid Submax. endurance muscle FGO, SO SO Total energy expenditure - s trváním pokles (?Havlíčková et al, 1991) Dominant way of restoration of ATP is oxidative phosphorylation Acute reaction of the body (neurohumoral controlled) for increase in supply of working muscles by energy sources and O2 - increase glucose in blood (from liver glycogen) - activation of FFA (activation of hormone sensitive lipase) Sources of energy by increasing exercise intensity energy expenditure kJ/min RQ carbohydrates = 1 RQ = CO2 1 g = 4,1 kcal O2 RQ fats = 0,7 1 g = 9,3 kcal glycogen fats glucose exercise intensity % VO2max (Hamar & Lipková, 2001) Sources of energy by increasing exercise intensity CO2 - expired RQ = CO2 O2 O2 - inspired RQ – respiration quotient – ratio between CO2 and O2 RQ carbohydrates = 1 = 1 l CO2/1 l O2 RQ fats = 0,7 = 0.7 l CO2/1 l O2 RQ normal (mixed) = 0,82 more O2 Lipids (FFA) - more energy (1 g = 9,3 kcal) - need more O2 (EE = 4,55 kcal) - use while enough of O2 (at rest, low intensity of exercise) Lipids (FFA) - more energy (1 g = 9,3 kcal) - need more O2 (EE = 4,55 kcal) - use while enough of O2 (at rest, low intensity of exercise) EE – energetic equivalent – shows amount of energy released while applied 1 liter of O2 on carbohydrate or on FFA Lipids (FFA) - more energy (1 g = 9,3 kcal) - need more O2 (EE = 4,55 kcal) - use while enough of O2 (at rest, low intensity of exercise) Carbohydrates - less energy (1 g = 4,1 kcal) - need less O2 (EE = 5,05 kcal) - use while not enough of O2 (higher intensity, and anaerobically as well) - small amount is always use at rest Sources of energy by increasing exercise intensity energy expenditure kJ/min RQ carbohydrates = 1 RQ = CO2 1 g = 4,1 kcal O2 RQ lipids = 0,7 1 g = 9,3 kcal glycogen fats glucose exercise intensity % VO2max (Hamar & Lipková, 2001) Mechanism of energy release in dependence on intensity VO2max Anaerobic threshold NOTE: Ideal model Aerobic threshold REST aerobic anaerobic Wasserman scheme of transport O2 a CO2 Muscle work Transport O2 and CO2 Ventilation O2 Mitochondrion muscles cardiovascular s. lungs AIR CO2 (Wasserman, 1999) The more O2 is delivered to working muscle, the higher aerobic production of energy (ATP) Better endurance performance, smaller production of lactic acid while the same speed of run, longer lasting exercise, etc. Wasserman scheme of transport O2 a CO2 Muscle work Transport O2 and CO2 Ventilation O2 Mitochondrion muscles cardiovascular s. lungs AIR CO2 (Wasserman, 1999) Fick equation: VO2 = Q × a-vO2 SV × HR VO2 – oxygen consumption [ml/min] Q – cardiac output [ml/min] a-vO2 – arteriovenous oxygen difference SV – stroke volume [ml] HR – heart rate [beet/min] a-vO2 – arteriovenous oxygen difference DA-V – arteriovenous oxygen difference - difference in the oxygen content of arterial and mixed venous blood - the value tells about the amount of oxygen used by working muscles - depends on the muscle ability to absorb and use the O2 from blood (perfusion, amount of capillary, mitochondrion, number of working muscles, etc.) - at rest 50 ml O2 from 1 L of blood - during exercise 150-170 ml O2 1 L of blood (100 ml krve is saturated by 20 ml O2) (1 L of blood is saturated by 200 ml O2) 1 L of blood is saturated by 200 ml O2 To ensure during exercise: ↑BF (breathing frequency, rate) - from 12-16 breath/min up 60 (70 and more) ↑TV (tidal volume) - from 0.5 L up 3 L Minute ventilation (VE) = - at rest 6 L/min = - during maximal exercise 180 L/min = BF × TV 12 × 0.5 60 × 3 . VO2 = Q × DA-V rest: SEDENTARY rest: TRAINED Q = HR × SV 4,9 L = 70 beet/min × 70 ml 4,9 L = 40 beet/min × 120 ml In work: increase of HR and SV - ↑ Q - SV increases till HR 110 – 120 beet/min (from 180 beet/min decreases) - HRmax = 220 - age . VO2 = Q × DA-V rest: SEDENTARY rest: TRAINED Q = HR × TV 4,9 L = 70 beet/min × 70 ml 4,9 L = 40 beet/min × 120 ml rest: VO2 = 4,9 L of blood × 50 ml O2 VO2 = 245 ml/min human (70kg): 245 : 70 = 3,5 ml O2/kg/min (1MET) . VO2 = Q × DA-V Max. exercise: Max. exercise: SEDENTARY TRAINED Q = SF × SV 20 L = 200 beet/min × 120 ml 35 L = 200 beet/min × 175 ml . VO2 = Q × DA-V Max. exercise: SEDENTARY: VO2max= 20 L of blood × 157 ml O2 VO2 max= 3140 ml/min 70 kg human: 3140 : 70 = 45 ml O2/kg/min (13 METs) . VO2 = Q × DA-V Max. exercise: TRAINED: VO2max= 35 L of blood × 170 ml O2 VO2 max= 5950 ml/min 70 kg human: 5950 : 70 = 85 ml O2/kg/min (25 METs) Definition and explanation of VO2max VO2max - is maximum volume of oxygen that by the body can consume during intense (maximum), whole body exercise. - expressed: - in L/min - in ml/kg/min - METs 1 MET - resting O2 consumption (3.5 ml/kg/min) 10 METs = 35 ml/kg/min 20 METs = 70 ml/kg/min Importance of VO2max Higher intensity of exercise Higher energy demands (ATP) Increase in oxygen consumption Lower VO2max = less energy = worse achievement Importance of VO2max During endurance activity is being ATP resynthesized mainly aerobically from lipids and carbohydrates. The more is O2 supplied to working muscles, the more higher is an amount of aerobically produced energy. It means higher speed of running, latest manifestation of fatigue, etc. It shows the capacity for aerobic energy transfer. Average values of VO2max Average (20/30 years) not trained: - female 35 ml/kg/min - male 45 ml/kg/min Trained: to 85 ml/kg/min (cross-country skiing) Decreases with age. Lower in female. Average values of VO2max Limitation factors of VO2max Muscle work Transport O2 and CO2 Ventilation O2 muscles cardiovascular s. lungs AIR CO2 (Wasserman, 1999) Limitation factors of VO2max 1) Lungs – no limitation factor 2) Muscles – is limitation factor 3) Cardiovascular system – dominant limitation factor Wasserman scheme of transport O2 a CO2 Muscle work Transport O2 and CO2 Ventilation O2 Mitochondrion muscles cardiovascular s. lungs AIR CO2 (Wasserman, 1999) VO2max = Qmax × DA-Vmax On increase of VO2max participate: 1) Increase of DA-Vmax – shares on increase about 20% 2) Increase of Qmax – shares aboout 70 - 85% Influence of the gender, health condition, age Heredity – the increase of VO2max by training only to max. 25% Gender – in female lower muscle mass, lover hemoglobin Age – decrease of active body mass, activity of enzymes… Sources of energy by increasing exercise intensity energy expenditure kJ/min RQ carbohydrates = 1 RQ = CO2 1 g = 4,1 kcal O2 RQ lipids = 0,7 1 g = 9,3 kcal glycogen fats glucose exercise intensity % VO2max (Hamar & Lipková, 2001) VO2max [ml/kg/min] 45 AT 50-60% VO2max 3,5 exercise intensity (speed, load, etc.) AT (aerobic threshold) - exercise intensity, when „exclusive“ aerobic covering ends. - exercise intensity, from which anaerobic covering starts and lactate is being produce - level of lactate: 2 mmol/L of blood VO2max [ml/kg/min] plateau 45 AnT 70-90 % VO2max AT 50-60 % VO2max 3,5 exercise intensity (speed, load, etc.) AnT (anaerobic threshold) - exercise intensity, when anaerobic covering exceed aerobic. - exercise intensity, when dynamic balance between production and breakdown of lactate is disturbed - level of lactate: 4 mmol/L of blood and is increasing (onset of blood lactate accumulation). - at about approximately 8 mmol/L o blood is impossible to continue in exercise (trained even 30 mmol/L of blood) AnT (anaerobic threshold) - can be estimate from VO2max: AnT = VO2max/3,5 + 60 AnT = 35/3,5 + 60 AnT = 70 %VO2max 1 MET 60 % of VO2max - AT VO2max [ml/kg/min] 45 AnT 70-90 % VO2max AT 50-60 % VO2max 3,5 exercise intensity (speed, load, etc.) lactate VO2max [ml/kg/min] energy sources onset of lactate accumulation – fiber type ↑ pH 45 AnT 70-90 % VO2max AT 50-60 % VO2max 3,5 4 mmol/L fat < sugar I., II. a, II. b L is oxidized (heart ,not working muscles) 2 mmol/L fat = sugar ? 1,1 mmol/L fat > sugar I., II. a I. exercise intensity (speed, load, etc.) (Hamar & Lipková, 2001) Exercise intensity during endurance activity (>30 minutes) can not be above AnT. 1) Before start of exercise - increase in O2 consumption (emotions, reflexions) 2) Initial phase of exercise (till 5 minutes) - rapid increase of the oxygen consumption 3) Steady state - balance between the energy required by working muscles and the rate of ATP produced by aerobic metabolism - O2 is almost constant - lactate level is constant - HR is in the range ±4 beats (right steady state) VO2max [ml/kg/min] O2 deficit AnT 3.5 0 before start 5 initial phase 30 steady state Time [min] • Oxygen deficit - Insufficient supply of working muscles with O2, at the beginning of exercise (slower ↑ SF and SV, BF and TV). - disbalance between O2 demands and supply leads to use of anaerobic metabolism – production of LACTATE ( ↑ H+ – metabolic acidosis – death point). - when O2 demands ensured – second breath - after termination of exercise the increased O2 consumption persists = oxygen debt VO2max [ml/kg/min] O2 deficit O2 debt AnT 3.5 0 before start 5 initial phase 30 steady state Time [min] Oxygen debt - synthesis of ATP and CP - resynthesis of lactate (back to glycogen in the liver, and oxidation by muscles and myocardium) - acceleration of release of lactate from muscles and better blood perfusion of muscles resynthesising lactate, is possible by low intensive exercise: (till 50 % VO2max – below AT) - recovery of myoglobin, hemoglobin, hormone, etc. - the major part (till 30 min), mild oxygen debt can persist 12-24 hours. VO2max [ml/kg/min] false steady state - above AnT major O2 debt AnT 3.5 0 before start 5 initial phase 25 steady state Time [min] VO2max [ml/kg/min] smaller O2 debt AnT AP 3.5 0 before start 30 2 initial phase steady state Time [min] oxygen consumption (L/min) trained - steady state is reached earlier sedentary - steady state is reached latter rest exercise time (min) (Hamar & Lipková, 2001) Practical importance of VO2max VO2max = 70ml/kg/min AnP = VO2max/3,5 + 60 80% VO2max = 35 ml/kg/min 70% male A female Practical importance of VO2max VO2max = 70ml/kg/min VO2max = 70 ml/kg/min 90% 80% male A male B Critical parameter of aerobic abilities is not VO2max, but AnT. However VO2max is conditional parameter of AnT.