PHYSIOLOGICAL ADAPTATIONS IN RESPONSE TO TRAINING

RESTING HEART RATE This is a reliable indicator of how hard the heart is working A trained athlete should have a lower resting heart rate than an untrained athlete Continued aerobic training should decrease the resting heart rate Rates as low as 40 bpm are possible for highly conditioned athletes

STROKE VOLUME A substantial increase in stroke volume is a long term effect of endurance training As a result of an increase in blood plasma there is more blood in circulation following training( can increase by as much as ½ a litre after eight days of training). This causes the ventricles to fill more than in the untrained athlete and will also cause more forceful contractions which results in less blood remaining in the ventricles Regular training causes the left ventricle to more completely fill during diastole The increased oxygen available to working muscles results in improved performance

CARDIAC OUTPUT Cardiac output in trained individuals is much higher during exercise than untrained individuals This greater output is achieved through increases in stroke volume As we grow older decreases in stroke volume will result in decreases in cardiac output

OXYGEN UPTAKE Maximal oxygen intake (VO2 max) refers to the maximal amount of oxygen that muscles can absorb and utilise at that level of work This is relatively easy to estimate using submaximal tests such as the bicycle ergometer test or the 12 minute run Measurements are expressed in ml/kg/min I.e. How much oxygen is consumed per kilogram of weight every minute

OXYGEN UPTAKE Training appreciably increases VO2 max this is most evident in untrained athletes who will see the greatest improvement The highest recorded value for a female 74ml/kg/min The highest recorded value for a male is 94ml/kg/min It would normally take an 8-12 week period of training to see an appreciable increase in VO2 max

LUNG CAPACITY No matter how efficient the cardiovascular system is in supplying blood to the tissues, endurance is hindered if the respiratory system does not supply enough oxygen to meet demand Total lung capacity is about 6000ml in males slightly less in females Vital capacity is the amount of air that can be expended after maximal inspiration – this increases slightly with training

LUNG CAPACITY Residual volume is the amount of air that cannot be moved out of the lungs – decreases slightly with training Tidal volume is the amount of air breathed in and out during a normal respiration – appears to increase at maximal levels of exercise but is unchanged at submaximal and rest

HAEMOGLOBIN LEVEL Haemoglobin is contained in the red blood cells of the body. Most oxygen in the body is transported by the haemoglobin in the red blood cells Haemoglobin levels increase as a result of training and this increases oxygen carrying capacity Training increases blood plasma as well as increasing red blood cell numbers.

MUSCLE HYPERTROPHY This refers to an increase in muscle size. As an immediate response to training, the muscle fibres increase in size as more fluid goes to the muscle. As a response to extended training, the muscles used will increase in size again as the fibres adapt to the training load and lead to an overall increase in muscle size.

FAST/SLOW TWITCH MUSCLE FIBRES The effect of training on the type of muscle fibre developed relates directly to specificity. Fast-twitch (Explosive Movement). Slow-twitch ( Longer Slower Contraction). Low to moderate activity will recruit slow-twitch fibres and increase the cross sectional area of these fibres. These fibres have a high aerobic endurance capacity and they are recruited also in our daily lifestyle.

MUSCLE FIBRES Fast-twitch muscle fibres need to be specifically developed through particular types of training. E.g. speed training & plyometrics. Any training athletes do for fast-twitch fibres must be maintained, otherwise the effects of training will be lost due to reversibility. It is a documented fact that athletes of dark skin origin have genetically more fast-twitch muscle fibres.