Chronic Training Adaptations Acute responses to exercise these

Chronic Training Adaptations

Acute responses to exercise: these occur immediately exercise begins as a response to the initial demands of exercise on the body. The acute responses return to near resting levels soon after the cessation of exercise. They include: • Cardiovascular • Respiratory • Muscular

Acute responses to exercise: Cardiovascular Numerous cardiovascular (heart, blood and blood vessels) responses occur when we start exercising. All are designed to facilitate the rapid and efficient delivery of increased amounts of oxygen to the working muscles in order to meet the body's increased demand for energy.

Acute responses to exercise: Cardiovascular Acute responses of the cardiovascular system to exercise include: • increased heart rate • increased stroke volume • increased cardiac output • increased blood pressure • redistribution of blood flow to working muscles • increased arterio-venous oxygen difference.

Acute responses to exercise: Respiratory Acute responses of the respiratory system to exercise are designed to facilitate an increase in the availability of oxygen and the removal of carbon dioxide. These responses include: • increased respiratory frequency (breathing rate) • increased tidal volume • Increased ventilation • increased oxygen uptake • increased diffusion – gas exchange alveoli-blood

Acute responses to exercise: Muscular Acute muscular system responses to exercise are those that occur in the working muscles themselves. These responses vary according to the type, intensity and duration of the exercise performed, and may differ according to the type of muscle fibre recruited (fasttwitch as opposed to slow-twitch fibres).

Acute responses to exercise: Muscular However, basically these responses include: • increased motor unit and muscle fibre recruitment • increased blood flow to the muscles • increased muscle temperature • increased muscle enzyme activity • increased oxygen supply and use • depleted muscle energy stores (ATP, creatine phosphate, glycogen and triglycerides).

Characteristics of Interplay of the three energy systems

Chronic Adaptation to training � Chronic training adaptations are long-term adaptations to regular training. �After completing a 6 -week training program, you may be able to observe some of these adaptations. Although, as we learned in chapter 11, anaerobic gains are more likely to be seen over 8 weeks, while aerobic gains may not be seen for up to 12 weeks. These gains are due to the body’s nervous system becoming more �The principle of specific adaptation to imposed demand (SAID) suggests that when the body is placed under some form of stress, it starts to make adaptations that will allow it to get better at withstanding that form of stress in the future.

Chronic Adaptation to training Unlike acute responses to exercises, chronic adaptations to training vary greatly and are dependant upon: �Type and method of training undertaken – aerobic vs anaerobic training. Chronic responses are very specific to the type of training performed. �The frequency, duration and intensity of the training undertaken – the greater these things, the more pronounced the adaptations �The individual’s capacities and hereditary factors (genetic make-up)

Cardiovascular training adaptations to Aerobic training

Aerobic training �What are the training methods that bring about improvement in aerobic capacity? �What principles of training must be followed to ensure there are chronic adaptations?

Cardio Vascular Training Adaptations All these bring about the more efficient delivery of oxygen to the working muscles which improves performance during aerobic activity.

What effect do �A more efficient aerobic system will enable an athlete to not work as hard at the same intensity or, more importantly, will increase their intensity while still using the aerobic system. This allows them to work harder for a longer period without succumbing to the fatiguing byproducts of the anaerobic systems (an increase in the lactate inflection point, LIP).

Increase Left Ventricle volume Enlargement of the Heart Muscle Increase in the left ventricle volume which means a greater volume of oxygenated blood can be pumped each beat. (SV) Therefore increases stroke volume

Stroke volume � Because the heart can hold more blood in the left ventricle, more blood can then be pumped out into the body per beat. The average resting stroke volume of an untrained person is as low as 71 millilitres per beat and the maximal level is 113 millilitres per beat. Compare this to a trained athlete, who has a resting stroke volume of 100 millilitres per beat and a maximal level at 179 millilitres per beat. �The trained athlete has an advantage at maximal levels because their heart can pump more blood to the working muscles, resulting in more oxygen to the working muscles. �Stroke volume is higher at rest, and during sub-maximal and maximal exercise in a trained person.

Stroke volume Effect of training on SV

Increase capillarisation of Heart Muscle

Heart Rate Heart rate Regular training produces the following effects on the heart rate: �lower resting heart rate �lower sub-maximal heart rate �slower increase in heart rate during exercise �faster return to resting heart rate after exercise. �Maximum heart rates do not change. HR max = 220 -age

Heart Rate

Heart Rate.

Cardiac Output

Cardiac Output HR X SV = Q˙ At Rest � Untrained: 5 L = 71 m. L X 70 bpm �Trained: 5 L = 100 m. L X 50 bpm At maximal intensity � HR X SV = Q˙ �Untrained: 200 bpm X 113 m. L = 22. 6 L �Trained: 200 bpm X 179 m. L = 35. 8 L

Cardiac Output HR X SV = Q˙ � Stroke volume, heart rate and cardiac output are all related, and having a higher cardiac output allows an athlete to work at a higher intensity more efficiently, This has two advantages for a predominantly aerobic athlete: �they can work at a higher intensity and still be working aerobically. This delays the use of anaerobic glycolysis and the accumulation of fatiguing metabolic byproducts (ADP, Pi, H+) �they can work longer at the same intensity, as the aerobic system is more efficient.

Blood Flow

Blood Flow and Distribution Redirects blood to working muscles (during exercise) from less active organs like digestive system and skin. Can lead to a 20% increase in blood flow to working muscle

Blood Volume � Plasma volume rises up to 1 litre after training. This also means there is an increase in the red blood cell count. Haemoglobin carries oxygen in the red blood cells and also increases, which means the oxygencarrying capacity is improved. Plasma helps with the removal of carbon dioxide and metabolic waste products, improving the effectiveness of waste removal. �Red blood cells: the cells of the body that transport oxygen �Haemoglobin: the iron containing protein of red blood cells

Blood pressure �Decreases during rest and submaximal exercise, particularly in sufferers of hypertension. �The benefits are health-related as high blood pressure is a major risk factor for cardiovascular disease.

Summary

Chronic adaptations to the Respiratory system as a result of aerobic training. � Aerobic training brings about a number of respiratory adaptations to the lungs and gaseous exchange.

Chronic adaptations to the Respiratory system as a result of aerobic training. Tidal volume �Tidal volume (TV) is the normal volume of air in the lungs that is displaced during inspiration and expiration. The amount of air inspired and expired in one breath increases after aerobic training at maximal levels, meaning more oxygen can be extracted from the air per breath.

Chronic adaptations to the Respiratory system as a result of aerobic training. Respiratory rate The respiratory rate (RR) is the number of breaths a person takes within a certain period of time (usually given as breaths per minute). At resting and sub-maximal levels, the respiratory rate (RR) decreases because lung function has improved and more oxygen can be extracted from one breath—meaning the athlete does not have to breathe as frequently.

Chronic adaptations to the Respiratory system as a result of aerobic training. Minute Ventilation or Ventilation � The minute ventilation (MV) is the volume of air that can be inhaled or exhaled from the lungs in 1 minute. It is calculated as: �TV X RR = MV

Chronic adaptations to the Respiratory system as a result of aerobic training. Minute Ventilation or Ventilation � Due to the increase in tidal volume and the decrease in respiratory rate, at rest the trained and untrained individual have similar minute ventilation; however, the untrained athlete will be breathing more heavily and more often. �During maximal activity the trained athlete has an advantage as they can inspire more air and consequently take in more oxygen per breath than the untrained individual, hence they have a higher minute ventilation.

Chronic adaptations to the Respiratory system as a result of aerobic training. Minute Ventilation or Ventilation: at submaximal intensity exercise the trained athlete has a lower ventilation due to improved oxygen extraction

Chronic adaptations to the Respiratory system as a result of aerobic training. Minute Ventilation or Ventilation: at maximal intensity exercise the trained athlete has a higher ventilation compared to an untrained athlete.

Chronic adaptations to the Respiratory system as a result of aerobic training. Lung diffusion � The ability of the blood to attract oxygen from the alveoli in the lungs also increases as a result of aerobic training. This allows more oxygen to be extracted per breath from the lungs into the bloodstream.

Chronic adaptations to the Respiratory system as a result of aerobic training. Oxygen Uptake Oxygen uptake at maximal activity (VO 2 max ) increases significantly. VO 2 max increases due to increases in cardiac output, minute ventilation, a – v O 2 difference, capillarisation, number of red blood cells and lung diffusion. These factors allow the body of a trained athlete to take up and utilise more oxygen than is possible for the untrained individual. Therefore, it takes longer before reaching the point at which oxygen delivery cannot keep up with oxygen demand, resulting in the athlete being able to work at higher intensities for longer without the anaerobic glycolysis system being required to supply additional energy for ATP resynthesis.

Chronic adaptations to the Respiratory system as a result of aerobic training. Oxygen Uptake

Chronic adaptations to the Respiratory system as a result of aerobic training. Oxygen Uptake

Chronic adaptations to the Muscles with Aerobic training Capillary density: increases the body adapts to aerobic training by increasing the number of capillaries around the muscle. This allows more oxygen to be taken up by the muscles as more blood is present near the muscle.

Increase capillarisation

Chronic adaptations to the Muscles with Aerobic training Mitochondria size and number increase: � Mitochondria are the site of Aerobic energy production in cells: here, food fuel (glycogen & fat) is combined with oxygen to produce energy for ATP resynthesis. After aerobic training the size and number of mitochondria both increase.

Chronic adaptations to the Muscles with Aerobic training Myoglobin increases The protein myoglobin is the oxygen carrying and storing molecule in the muscle. After an aerobic training program, the amount of myoglobin increases, resulting in more sites for oxygen transport and storage in the muscles.

Chronic adaptations to the Muscles with Aerobic training Oxidative Enzymes increase in amount Oxidative enzymes help with the breakdown of food fuels during aerobic energy production for ATP resynthesis. These increase as a result of aerobic training. This increases speed of the breakdown of triglcerides and glycogen. (different to glycolytic enzymes these are for breakdown of glycogen in anaerobic glycolysis. Remember oxidative for oxygen ie areobic energy production. )

Chronic adaptations to the Muscles with Aerobic training Muscle fuel stores � The stores of triglycerides in the muscle increase. �The stores of glycogen in the muscle increase. � ATP: due to the increase in muscle size, the muscle can store more ATP.

Chronic adaptations to the Muscles with Aerobic training Muscle fibres �Muscle fibres: aerobic activities rely predominantly on Type I (slow twitch, oxidative) muscle fibres. In response to aerobic training, Type I fibres get larger. In recent studies, scientists have found that after prolonged training in endurance sports some Type II fibres (IIA, fast twitch, partially oxidative) can take on the characteristics of Type I fibres, while Type IIB fibres can take on the characteristics of Type IIA fibres.

Chronic adaptations to the Muscles with Aerobic training a-v O 2 difference �The arteriovenous oxygen difference (a – v. O 2 ) is the difference between the oxygen content in arterial blood and venous blood. In a trained athlete, more oxygen is absorbed from the blood into the muscles during sub-maximal and maximal exercise.

Chronic adaptations to the Muscles with Aerobic training a-v O 2 difference

a-v O 2 difference Arterio-venous oxygen difference – will rise after a long-term training program. (Oxygen Extraction)

Response of muscular system to Aerobic training.

Chronic adaptations to aerobic training. All the chronic adaptations lead to the improved ability of the body to take in, transport and utilise oxygen. (increase VO 2 max). This also leads improved ability to transport lactate. What effect would this have on LIP?

LIP � An individual’s LIP can be raised by regular endurance training. Training near the LIP is an adequate training stimulus for an untrained individual, but a higher intensity is necessary for endurance-trained athletes. Most of the improvements in the LIP progressively occur over 8 to 12 weeks of training, but small changes may accrue beyond this period. � An individual’s LIP varies depending on their training status. LIP in untrained individuals typically occurs between 55 to 70% of VO 2 max. In well-trained individuals the LIP typically occurs between 75– 90% of VO 2 max. Therefore with appropriate training the lactate inflection training point will occur at higher absolute exercise intensity ( VO 2, speed, watts) and a higher relative exercise intensity (% VO 2 max. ) in a more trained versus untrained athlete. � The adaptations that lead to an improvement in the LIP are localised to the specific muscle cells used in chronic exercise training. Greater mitochondria mass and an increased capability to oxidise fat and carbohydrate in response to endurance training and lead to an improvement in LIP.

Lactate Inflection Point LIP

Glycogen sparing

Adaptation to Anaerobic training. �Which training methods are used for improving anaerobic capacity?

Response of muscular system. Anaerobic training Muscle Hypertrophy – Anaerobic training (weights, interval etc…) significantly enlarge fast-twitch muscle fibres (mainly type II “b”). therefore greater strength Increase stores of ATP & PC, as well as Glycogen Increase enzymes to breakdown Glycogen. (increase glycolytic capacity)

Response of muscular system. Anaerobic training Increase ventricle thickness of cardiac muscle, making it stronger for more forceful contraction Contractility of the muscles – muscles contract faster and stronger after anaerobic training. (due to more proteins) Increase myosin ATPase – enzyme that splits ATP.

Response of muscular system. Anaerobic training Increase muscle buffering capacity can more easily handle Lactic Acid Muscle Hyperplasia – Increase in muscle fibre number (only new research.

Response of muscular system. Anaerobic training others Increase strength and size of connective tissue & ligaments Increase in the number of motor units recruited for maximal contraction Increase speed of nerve-impulse transmission Increase speed of muscular contraction

Response of muscular system. Anaerobic training

Lactate Tolerance �Lactate tolerance training develops the body's ability to use anaerobic energy sources and to tolerate high lactate levels. This capacity will govern the contribution to performances where energy production is a limiting factor (e. g. , 200 m butterfly). Individuals can improve this ability to tolerate the pain of lactic acidosis but only up to a point. There comes a time when the acidity is so extreme that it seriously disrupts an individual's capacity to perform.

Practice Questions