VCE Physical Education Unit 4 - Chronic Adaptations

Chronic adaptations to exercise

Physiological changes which occur to the cardiovascular, respiratory and muscular systems as a result of long-term training.

Adaptations are retained unless training ceases (reversibility)

Adaptations dependent on

- specificity

- frequency, intensity and duration

- overload

- individuality

- hereditary factors

SAID

Specific Adaptation to Imposed Demands

Aerobic chronic adaptations

Working harder for longer

Cardiovascular adaptations are changes that occur to the HEART, BLOOD, and BLOOD VESSELS

Improved efficiency of aerobic system

1) Provide energy to the working muscles

2) Aid in more efficient removal of waste products

Increased left ventricle size and volume

Cardiac hypertrophy

More oxygenated blood = increased stroke volume and cardiac output

Greater volume of blood ejected from heart, thus providing more oxygen for athlete to use

Capillarisation of heart muscle

Heart to beat more strongly and efficiently

Blood supply to the heart muscle increased during rest and work

Increased stroke volume

Amount of blood pumped out of heart (left ventricle) per beat

More blood pumped per beat resulting in trained athlete having lower HR at rest and submaximal activity.

SV allows for more O2 to be delivered to working muscles, improving ability to resynthesise ATP aerobically

Increased cardiac output

Amount of blood pumped from the left ventricle per minute

More blood pumped per minute resulting in trained athlete having lower HR at rest and submaximal activity

Q allows for more O2 to be delivered to working muscles, improving ability to resynthesise ATP aerobically

Decreased heart rate

At rest, a trained athletes HR is lower due to increased efficiency of the cardiovascular system and higher stroke volume

There is a slower increase in HR during exercise and faster return to resting HR after exercise

Decreased blood pressure

Systolic = during contraction

Diastolic = during relaxation

- Decreased strain on heart

- Improved elasticity of blood vessels

- Decreased risk of heart conditions

Systolic and diastolic BP levels may decrease during rest and submaximal exercise

Increased blood volume

Can increase up to 1L after training

= higher red blood cell count (increased O2 carrying capacity)

decreased viscosity of blood (flows easier); increased waste removal and increased thermoregulatory ability due to increased plasma

Blood changes

Blood lactate concentration decrease

Enables athletes to work aerobically at higher intensities before LIP is reached

Tidal Volume

Tidal volume increases

More O2 can be extracted from the air per breath due to increased strength and endurance of the respiratory muscles

Respiratory Rate

Respiratory rate decreases at rest and submaximal exercise

Lung function has improved and more O2 can be extracted from one breath so athlete doesn't have to breathe as frequently

Minute Ventilation

Minute ventilation increased at maximal intensity

TV x RR = MV

MV between trained and untrained athletes will be relatively similar at rest, but at max exercise the trained athlete will have a higher MV due to having an increased TV.

Pulmonary Diffusion

The ability of blood to extract oxygen from the alveoli increases

Allows more oxygen to be extracted per breath from the lungs into the bloodstream for greater delivery of oxygen to working muscles and greater exchange of CO2 to remove waste

Oxygen Uptake

Maximal amount of oxygen that can be breathed in, transported and utilised by the body in one minute is increased

This means an athlete can work at higher intensities or longer durations using the aerobic system and therefore not fatiguing

a-vO2 difference

Oxygen content in arterial blood and venous blood is increased as trained athletes can absorb more O2 from the blood and into the muscles, therefore having less in venous blood; greater difference

Mitochondria number, size and surface area

Increased mitochondria number, size and surface area

Helps with energy production

Capillary density

Density of capillaries has increased

This means more oxygen can be taken up by the muscle as more blood is present

Myoglobin content

Myoglobin content has increased;

absorption and storage of O2 within muscles is more efficient

Oxidative enzymes

Oxidative enzyme levels has increased

This helps with metabolising food fuels;

Increased oxidation of triglycerides for glycogen sparing - working @ higher intensity for longer = delayed LIP

Muscular fuel stores

Increased levels of muscular fuel stores

Triglycerides and glycogen in slow twitch muscle fibres - less reliance on anaerobic systems

ATP

Due to the increased muscle size, more ATP can be stored which means more energy can be produced

Muscle fibre types

Type 1

Type 2A

Type 2B

Type 1

Slow twitch

- large amounts of myoglobin

- large numbers of mitochondria and blood capillaries

- red

- high capacity for generating ATP by oxidative processes

- split ATP at a slow rate

- slow contraction velocity

- very resistant to fatigue

Type 2A

Fast twitch

- split ATP at a rapid rate

- fast contraction velocity

- resistant to fatigue

Type 2B

Fast twitch

- low myoglobin content

- few mitochondria and blood capillaries

- large amounts of glycogen

- white

- generate ATP anaerobically

- fatigue easily

- split ATP at a fast rate

- fast contraction velocity

Cardiac hypertrophy

Increase in thickness of the left ventricular walls

Little or no change to SV; a more forceful contraction takes place (more forceful ejection of blood)

Muscular hypertrophy

Growth or increase in size of muscle cells (cross-sectional area of muscle)

Type 2A and 2B fast twitch fibres increase

Occurs as a result of increase size and number of myofibrils per muscle fibre and increased myosin and actin myofilaments

Muscular stores of ATP, CP and ATPase

Increased ability to store ATP, CP and ATPase

Increased capacity of the ATP-PC system, greater release and faster restoration of ATP during high intensity activity

ATPase = enzyme that breaks down ATP

Glycolytic capacity

Increased glycolytic capacity

Greater opportunity to create energy using glycogen as there is more stored

Glycolytic enzymes

Increase in glycolytic enzyme quantity

Speed up breakdown of glycogen which increases the capacity of the anaerobic glycolysis system

Motor unit recruitment

More motor units are recruited; more forceful contractions (greater strength and power produced)

Speed of muscular contraction

Muscle can contract faster, which is beneficial to speed athletes who have to sprint, swim, etc

Speed and strength of tendons and ligaments

More power generated

Reduced risk of tearing/injuring tendons and ligaments

Lactate tolerance

Increased ability to tolerate lactate build up

When working anaerobically you are working above LIP and therefore produced by-products at a faster rate

Ability to tolerate higher levels of fatiguing by products through an increase in the muscle buffering capacity (neutralise the acid accumulated)

Greater efficiency in neural recruitment patterns

Smoother acceleration of body parts = greater power

Increase in CNS activation

Increase in central nervous system activation

Increase in firing rates

Type 2A and 2B muscle fibres

Increased strength and duration of contraction