Exercise or training regularly over an extended period of time (3 times per week for 6-8 weeks) leads to the development of long-term or chronic adaptations to training. Evidence of these adaptations can occur at various stages
Once achieved, these adaptations are retrained unless training ceases. Upon cessation, the body will gradually revert to its pre-training condition (de-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)
Chronic Adaptations to Aerobic (endurance) Training:
• Minimum period is 6 weeks
• More evident over 12 weeks
• Adaptations occur at both tissue and system levels.
Cardiorespiratory Adaptations to Aerobic (endurance) Training
• Chronic cardio-respiratory adaptations are primarily designed for more efficient delivery of larger quantities of oxygen to working muscles. • They decrease cardiovascular disease (CVD)and other health-related illnesses. • Cardio-respiratory adaptations are best developed through continuous, fartlek and longer interval type training.
Cardiac hypertrophy (increased ventricular volume):
• Enlargement of the heart muscle itself
• Increase in size and volume of the ventricular chambers, particularly the left ventricle occurs. • Significantly increases stroke volume
Increased capillarisation of the heart muscle:
• Increase in capillarisation of the heart muscle itself (Increase in capillary density and blood flow to the heart muscle) • Increased supply of blood and oxygen allows the heart to beat more strongly and efficiently during rest and exercise • Coronary protective benefit (therefore decreased risk of heart attack) Increased stroke volume of the heart:
Heart ejects a greater volume of blood with each beat
Stroke volume is greater at rest, during sub-max and max workloads for a trained athlete compared to an untrained person Eg. Average stroke volume at rest:
• Untrained male - 70-80millilitres/beat,
• Trained male endurance athlete - 100millilitres/beat or more. During maximal exercise:
• Untrained person – 110 millilitres/beat
• Trained person – 130 millilitres/beat
• Elite endurance athletes – 190 millilitres/beat
Trained and untrained females have lower stroke volumes than their male counterparts under all exercise conditions, mainly due to a smaller heart size
Lower resting heart rate:
The amount of oxygen required by an individual at rest does not alter as a result of their training status. At rest, it takes about 5 litres of blood per minute (cardiac output) to circulate around the body to supply the required amount of oxygen to the body cells Cardiac output (Q) is equal to stroke volume (SV) multiplied by heart rate (HR).
Q = SV x HR
However, if an individual has developed a greater stroke volume, the heart does not have to beat as frequently to supply the required blood flow Eg.
Q = SV x HR
5L/min = 70 mL/beat x 71 beats/min
Q = SV x HR
5L/min = 100 mL/beat x 50 beats/min
This is why resting heart rate is a useful indicator of aerobic fitness. Lower resting heart rate – greater level of aerobic fitness • Elite – 35bpm (marathon runners, triathletes, distance swimmers) • Average adult male – 70bpm
Lower heart rate during sub-maximal workloads:
Mainly a result of increased stroke volume.
The heart works more efficiently - (More blood is pumped with...