KEY KNOWLEDGE KEY SKILLS Long term (chronic) training adaptations occurring at the cardiovascular, respiratory and muscular systems. Describe how long term training changes to the cardiovascular, respiratory and muscular systems contribute to physical improvements. © Cengage Learning Australia 2011

© Cengage Learning Australia 2011

Chronic adaptations = long term physiological changes in response to increased demands placed on the body through training. Each adaptation is either structural or functional © Cengage Learning Australia 2011

Cardiovascular adaptations as a result of aerobic training (Structural, Functional) Heart Left ventricle size (cardiac hypertrophy) – greatest increase occurs with aerobic training Causes an  in stroke volume (SV) – due to more forceful contractions and hence an  cardiac output (Q) At rest and sub-max: Q remains the same due to an  in stroke volume but  in heart rate (bradycardia) in stroke volume is due to:  left ventricle volume and mass  causing more forceful contractions  diastolic filling time (due to a longer gap between heart beats) Also more blood can be refilled into the ventricle during diastole because of an  venous return, left ventricle volume and elasticity. This enables a greater volume of blood being pushed out during systole (SV) © Cengage Learning Australia 2011

Question Compare and contrast the heart size between the three individuals. Explain how these structural changes will influence their performance.

How does this benefit performance? During submaximal exercise: Reach steady state more quickly and at a lower heart rate – due to the improved efficiency of the CV system in delivering the oxygen During maximal exercise:  Q enables greater delivery of oxygen, removal of by-products and enables aerobic glycolysis to occur to a higher percentage Recovery:  recovery heart rates – takes less time for the body to return back to normal (important for a sprint athlete to still do aerobic training…to speed up their rate of recovery)

Blood vessels Redistribution of blood flow  capillary density surrounding heart muscle – therefore improved blood supply to the heart, delivering more oxygen to meet its demands of the heart muscle (myocardium):  slightly at rest and during submaximal  capillary density surrounding muscles due to muscle hypertrophy (the larger the muscle = the denser the capillary network) Mostly occurs in slow twitch as they have an increased number of mitochondria per fibre and a greater number of capillaries around each fibre – why???  capillary density =  in supply of oxygen, nutrients to the heart and muscle and enhanced waste removal Redistribution of blood flow Rest & submaximal: blood flow to muscles  (muscles with a high oxidative capacity receive more blood than those at a low) – why?? The muscle’s ability to extract and use the oxygen delivered is enhanced and so less blood needs to flow to the muscle  blood flow to the skin – aids thermoregulation (fitter athletes sweat more)

Blood  blood volume:  plasma volume (days) and  red blood cell (RBC) count (weeks)  plasma volume – aids the  SV ( refilling) and aids thermoregulation and heat dissipation (water availability contained within plasma)  haemoglobin - due to  blood volume ( Hb amount not an  in concentration)  blood pressure (rest and sub-max – no change at maximal)  blood lactate concentration ( production and  rate of removal) Therefore endurance athletes can delay LIP The ability to sustain high intensities without accumulating lactate is strongly related to performance in endurance events. LIP: Balance between lactate entry and removal from the blood Aerobic training: athletes become better at clearing the lactate due to an  in oxidation (the aerobic pathway) and gluconeogenesis (production of glucose in the liver from non-carbohydrate substances i.e. lactate) They can therefore work at higher intensities before reaching the LIP

Blood lactate concentration decreases with aerobic training and clearance rates increase. Therefore, the LIP (lactate inflection point) is reached at a higher exercise intensity © Cengage Learning Australia 2011

Respiratory Adaptations as a result of aerobic training  total lung volume capacity through an  in pulmonary function Tidal volume is unchanged at rest (because you don’t need to breathe in more per breath)  diffusion of oxygen across alveolar-capillary membrane and carbon dioxide across the tissue-capillary membrane (at rest, submax, max ex.) due to:  lung volume – provides  surface area and therefore more sites for diffusion

Rest, submaximal:  ventilation rate (V=TV x RR) Maximal:  ventilation rate ( TV & RR) – proportionate to carbon dioxide production ( intensity =  demand for oxygen and production of carbon dioxide)  Ventilatory efficiency: less oxygen is needed for breathing mechanisms; more available to the working muscles VO2 max – what is it? VO2 at rest, submaximal: same/ -  SV means the oxygen demands are being met more efficiently VO2 maximal: (SV X HR X AVO2 diff) – why this equation?? All these factors cause the increase in VO2 max What are the units for VO2 max? l/min v ml/kg/min  what is the difference? Absolute v Relative e.g. 60kg v 80kg male – both with a VO2 max of 6.3l/min. Who’s fitter?!

© Cengage Learning Australia 2011

Muscular Adaptations for aerobic training Muscle structure Fast twitch maximise their aerobic potential through aerobic (Type 2a) – most adaptations occur with slow twitch fibres Slow twitch fibres: Hypertrophy: increased capillary density around the fibre – ST take up a greater area of the muscle than FT (in endurance trained athletes) AVO2 diff Increased O2 extraction from the blood by the muscles  due to an increase in capillary density of the fibre which increases the diffusion rate (of O2, CO2) Increased diffusion + increased redistribution of the blood to the muscles causes an increased in AVO2 diff

Myoglobin and Mitochondria  Myoglobin: it delivers O2 across the cell membrane and into the mitochondria (the site of aerobic glycolysis). It  the available oxygen for aerobic respiration  Mitochondria: size, number & surface area – enhancing the capacity of the muscle to produce ATP aerobically.  in size and number of the sites available for the release of ATP increases the ability of the body to perform aerobically  in number increases the oxidative enzymes than allow endurance athletes to work at higher percentages of their VO2 max without accumulating blood lactate. Increased Oxidation of Fats  Oxidation of free fatty acids during submaximal exercise - advantageous during endurance events as it allows athletes to conserve their glycogen stores (glycogen sparing) This is achieved by:  in intramuscular triglycerides  in free fatty acids in oxidative enzymes

Increased Oxidation of glycogen  ability to oxidise glycogen through:  in enzyme activity and concentration  in muscle glycogen stores The factors work together to improve all aspects of the aerobic ability of the muscle