Physiological Adaptations in Response to Aerobic Training
Resting Heart Rate Trained athletes have a lower resting heart rate due to increased efficiency of the cardiovascular system and higher stroke volume This is most evident in the recovery phases The trained athlete can recover faster (HR ’s faster) due to a more efficient cardiovascular system.
Stroke Volume Amount of blood pumped out per beat Increases with aerobic training This occurs due to the heart becoming stronger and the left ventricle fills more completely during diastole (resting phase of cardiac contraction) More blood more 02 = performance in aerobic activity
Cardiac Volume Cardiac Volume or Cardiac Output – the amount of blood pumped per minute Increases mainly due to Stroke volume: CO = SV x HR More blood more 02 = performance in aerobic activity
Oxygen Uptake Oxygen Uptake (V02 max) is the best indicator of cardiorespiratory endurance because it indicates the maximum amount of 02 that muscles can absorb and utilise at that level of work Training increases V02 max Lower in females due to less lean muscles mass
Lung Capacity Lung capacity (amount of air that the lungs can hold) is increased only at the maximal exercise level Generally there is little change with training Females have a lower lung capacity due to smaller size
Haemoglobin Level Haemoglobin – substance in the blood that bonds to 02 Increases with training, particularly with altitude training More haemoglobin more 02 = performance
Blood Pressure Blood pressure – measure of pressure that blood exerts on the inner artery walls Reduces with training, especially if hypertensive prior to training
Muscle Hypertrophy Muscle hypertrophy refers to muscle growth together with an increase in the size of muscle cells, that is, bulking up. This occurs as a result of strength or resistance training that stimulates activity in muscle fibres causing them to grow. Hypertrophy does not occur as a result of aerobic training. Muscle fibres enlarge after training. Reasons for this increase in size include the higher proportion of myofibrils (the contractile element of the muscles). The fibres also enlarge as a result of increased stores of glycogen and the energy-supplying compounds (ATP and phosphocreatine - PC) needed for the increased muscle size.
Effect on Fast/Slow Twitch Fibres There are two types of muscle fibre: slow-twitch muscle fibres fast-twitch muscle fibres. Ratio of fast to slow-twitch fibres is thought to be genetically determined. The metabolic capabilities of both types of fibres can improve through specific strength and endurance training. Sprinters and weight lifters have a large percentage of fast-twitch fibres. Marathon runners generally have a higher percentage of slow twitch fibres.
Effect on Fast/Slow Twitch Fibres The adaptations that can occur in response to training are shown in the table below. Aerobic training - in slow- Anaerobic training - in fast- twitch fibres twitch fibres •hypertrophy of slow-twitch muscle •Increase and efficiency of ATP- fibres PCsupply •increased capillary supply to •increased glycolytic enzymes which muscle fibres, improving gaseous improve functioning of the cell exchange & movement of nutrients •hypertrophy of red-twitch muscle and waste products fibres •increased number and size of •increased tolerance of lactic acid, mitochondria (energy factory of allowing performance to be cells) enabling more efficient sustained for longer periods energy production •muscle contractions can be made •significant increase in myoglobin more forcefully and quickly as there content (transports oxygen from are a greater volume of fast-twitch the cell membrane to mitochondria) fibres
Remember:Physiological Adaptations in Response to Aerobic Training Britney Blood pressure Spears Stroke Volume Obviously O2 Uptake Lost Lung Capacity Her Haemoglobin levels Recording Resting HR Contract Cardiac Output Major Muscle Hypertrophy Fail Fibres