Exercise physiology Exercise physiology Recommended literature 1 Wilmore

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 (4 th ed. ). Champaign, IL: Human Kinetics. 3) Brooks, G. A. , Fahey, T. D. , & White, T. P. (1995). Exercise physiology: human bioenergetics and its applications (2 nd 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)

Změny vybraných parametrů

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 + 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 Co. A NADH (nicotinamide adenine dinucleotid) and FADH Citric acid cycle CO 2

Energy metabolism oxidative phosphorylation – in mytochondrion (electron transport chain) NADH + O 2 + 3 ADP 3 ATP + NAD + H 2 O 1 NADH=3 ATP FADH + O 2 + 2 ADP 2 ATP + FAD + H 2 O 1 FADH=2 ATP

Energy metabolism From one molecule G GG Anaerobic glycolysis 2 ATP 3 ATP Aerobic glycolysis 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 the energy increases the temperature of 1 gram H 2 O from 14. 5ºC to 15. 5ºC.

Energy metabolism Fat - triglyceride = FFA (free fat acids) + glycerol in subcutaneous tissue (141 000 kcal). Adipose tissue reduction Glucose metabolism triglyceride Hormone- FFA + Glycerol sensitive lipase Beta oxidation NADH and FADH Acetyl Co. A NADH and FADH Citric acid cycle CO 2

Energy metabolism proteins FFA anaerobic Glucose pyruvate and/or Acetyl Co. A lactic acid Citric acid cycle NADH and FADH Electron transport chain plasma membrane

Energy metabolism Anaerobic metabolism - only carbohydrate - increases when lack of O 2 and not enough time - lower amount of ATP, but very fast and huge in short time - production of lactic acid Anaerobic metabolism - carbohydrate, fats, proteins - enough of O 2 - 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 + E ATP is only the one immediate source of energy for muscles work, etc. Other ways of the creation (phosporylation): ATP + C ATP + AMP ADP + CP(creatine phosphate) ADP + ADP

Zones of energy supply Anaerobic free of lactic acid Anaerobic with lactic acid Aerobic free of lactic acid

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 O 2 - increase glucose in blood (from liver glycogen) - activation of FFA (activation of hormone sensitive lipase)

Mechanism of energy release in dependence on intensity VO 2 max Anaerobic threshold NOTE: Ideal model Aerobic threshold REST aerobic anaerobic

Sources of energy by increasing exercise intensity energy expenditure k. J/min RQ carbohydrates = 1 RQ = CO 2 1 g = 4, 1 kcal O 2 RQ fats = 0, 7 1 g = 9, 3 kcal glycogen fats glucose exercise intensity % VO 2 max (Hamar & Lipková, 2001)

Sources of energy by increasing exercise intensity CO 2 - expired RQ = CO 2 O 2 - inspired RQ – respiration quotient – ratio between CO 2 and O 2 RQ carbohydrates = 1 l CO 2/1 l O 2 RQ fats = 0, 7 = 0. 7 l CO 2/1 l O 2 RQ normal (mixed) = 0, 82 more O 2

Lipids (FFA) - more energy (1 g = 9, 3 kcal) - need more O 2 (EE = 4, 55 kcal) - use while enough of O 2 (at rest, low intensity of exercise)

Lipids (FFA) - more energy (1 g = 9, 3 kcal) - need more O 2 (EE = 4, 55 kcal) - use while enough of O 2 (at rest, low intensity of exercise) EE – energetic equivalent – shows amount of energy released while applied 1 liter of O 2 on carbohydrate or on FFA

Lipids (FFA) - more energy (1 g = 9, 3 kcal) - need more O 2 (EE = 4, 55 kcal) - use while enough of O 2 (at rest, low intensity of exercise) Carbohydrates - less energy (1 g = 4, 1 kcal) - need less O 2 (EE = 5, 05 kcal) - use while not enough of O 2 (higher intensity, and anaerobically as well) - small amount is always use at rest

Sources of energy by increasing exercise intensity energy expenditure k. J/min RQ carbohydrates = 1 RQ = CO 2 1 g = 4, 1 kcal O 2 RQ lipids = 0, 7 1 g = 9, 3 kcal glycogen fats glucose exercise intensity % VO 2 max (Hamar & Lipková, 2001)

Wasserman scheme of transport O 2 a CO 2 Muscle work Transport O 2 and CO 2 Ventilation O 2 Mitochondrion muscles cardiovascular s. lungs AIR CO 2 (Wasserman, 1999)

The more O 2 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 O 2 a CO 2 Muscle work Transport O 2 and CO 2 Ventilation O 2 Mitochondrion muscles cardiovascular s. lungs AIR CO 2 (Wasserman, 1999)

Fick equation: VO 2 = Q × a-v. O 2 SV × HR VO 2 – oxygen consumption [ml/min] Q – cardiac output [ml/min] a-v. O 2 – arteriovenous oxygen difference SV – stroke volume [ml] HR – heart rate [beet/min]

a-v. O 2 – 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 O 2 from blood (perfusion, amount of capillary, mitochondrion, number of working muscles, etc. ) - at rest 50 ml O 2 from 1 L of blood - during exercise 150 -170 ml O 2 1 L of blood (100 ml krve is saturated by 20 ml O 2) (1 L of blood is saturated by 200 ml O 2)

1 L of blood is saturated by 200 ml O 2 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

. VO 2 = Q × DA-V rest: SEDENTARY rest: TRAINED Q = HR × SV 4, 9 L = 70 beat/min × 70 ml 4, 9 L = 40 beat/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

. VO 2 = Q × DA-V rest: SEDENTARY rest: TRAINED Q = HR × TV 4, 9 L = 70 beat/min × 70 ml 4, 9 L = 40 beat/min × 120 ml rest: VO 2 = 4, 9 L of blood × 50 ml O 2 VO 2 = 245 ml/min human (70 kg): 245 : 70 = 3, 5 ml O 2/kg/min (1 MET)

. VO 2 = Q × DA-V Max. exercise: SEDENTARY TRAINED Q = SF × SV 20 L = 200 beat/min × 120 ml 35 L = 200 beat/min × 175 ml

. VO 2 = Q × DA-V Max. exercise: SEDENTARY: VO 2 max= 20 L of blood × 157 ml O 2 VO 2 max= 3140 ml/min 70 kg human: 3140 : 70 = 45 ml O 2/kg/min (13 METs)

. VO 2 = Q × DA-V Max. exercise: TRAINED: VO 2 max= 35 L of blood × 170 ml O 2 VO 2 max= 5950 ml/min 70 kg human: 5950 : 70 = 85 ml O 2/kg/min (25 METs)

Definition and explanation of VO 2 max - 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 O 2 consumption (3. 5 ml/kg/min) 10 METs = 35 ml/kg/min 20 METs = 70 ml/kg/min

Importance of VO 2 max Higher intensity of exercise Higher energy demands (ATP) Increase in oxygen consumption Lower VO 2 max = less energy = worse achievement

Importance of VO 2 max During endurance activity is being ATP resynthesized mainly aerobically from lipids and carbohydrates. The more is O 2 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 VO 2 max 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 VO 2 max

Limitation factors of VO 2 max Muscle work Transport O 2 and CO 2 Ventilation O 2 muscles cardiovascular s. lungs AIR CO 2 (Wasserman, 1999)

Limitation factors of VO 2 max 1) Lungs – no limitation factor 2) Muscles – is limitation factor 3) Cardiovascular system – dominant limitation factor

Wasserman scheme of transport O 2 a CO 2 Muscle work Transport O 2 and CO 2 Ventilation O 2 Mitochondrion muscles cardiovascular s. lungs AIR CO 2 (Wasserman, 1999)

VO 2 max = Qmax × DA-Vmax On increase of VO 2 max 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 VO 2 max 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 k. J/min RQ carbohydrates = 1 RQ = CO 2 1 g = 4, 1 kcal O 2 RQ lipids = 0, 7 1 g = 9, 3 kcal glycogen fats glucose exercise intensity % VO 2 max (Hamar & Lipková, 2001)

VO 2 max [ml/kg/min] 45 AT 50 -60% VO 2 max 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

VO 2 max [ml/kg/min] 45 plateau An. T 70 -90 % VO 2 max AT 50 -60 % VO 2 max 3, 5 exercise intensity (speed, load, etc. )

An. T (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)

An. T (anaerobic threshold) - can be estimate from VO 2 max: An. T = VO 2 max/3, 5 + 60 An. T = 35/3, 5 + 60 An. T = 70 %VO 2 max 1 MET 60 % of VO 2 max - AT

VO 2 max [ml/kg/min] 45 An. T 70 -90 % VO 2 max AT 50 -60 % VO 2 max 3, 5 exercise intensity (speed, load, etc. )

lactate VO 2 max [ml/kg/min] energy sources onset of lactate accumulation – fiber type ↑ p. H 45 An. T 70 -90 % VO 2 max AT 50 -60 % VO 2 max 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 An. T. 1) Before start of exercise - increase in O 2 consumption (emotions, reflexions) 2) Initial phase of exercise (till 5 minutes) - rapid increase in the oxygen consumption 3) Steady state - balance between the energy required by working muscles and the rate of ATP produced by aerobic metabolism - O 2 is almost constant - lactate level is constant - HR is in the range ± 4 beats (real steady state)

VO 2 max [ml/kg/min] O 2 deficit An. T 3. 5 0 before start 5 initial phase 30 steady state Time [min]

• Oxygen deficit - Insufficient supply of working muscles with O 2, at the beginning of exercise (slower ↑ SF and SV, BF and TV). - disbalance between O 2 demands and supply leads to use of anaerobic metabolism – production of LACTATE ( ↑ H+ – metabolic acidosis – death point). - when O 2 demands ensured – second breath - after termination of exercise the increased O 2 consumption persists = oxygen debt

VO 2 max [ml/kg/min] O 2 deficit O 2 debt An. T 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 % VO 2 max – below AT) - recovery of myoglobin, hemoglobin, hormone, etc. - the major part (till 30 min), mild oxygen debt can persist 12 -24 hours.

VO 2 max [ml/kg/min] false steady state - above An. T major O 2 debt An. T 3. 5 0 before start 5 initial phase 25 steady state Time [min]

VO 2 max [ml/kg/min] smaller O 2 debt An. T 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 VO 2 max = 70 ml/kg/min An. P = VO 2 max/3, 5 + 60 80% VO 2 max = 35 ml/kg/min 70% male A female

Practical importance of VO 2 max = 70 ml/kg/min VO 2 max = 70 ml/kg/min 90% 80% male A male B

Critical parameter of endurance abilities is not VO 2 max, but An. T. However VO 2 max is conditional parameter of An. T.