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Basic Sports Science

Lesson 2

* Acute responses to exercise: immediate responses during exercise

Chronic adaptations: longer-term reactions upon regular completion of exercise

* The cardiovascular system (heart, blood, blood vessels) works closely in tandem with the respiratory system (lungs and airways) to move the blood through the blood vessels to the tissues and organs of the body to deliver oxygen and nutrients.

* The depth and frequency of breathing, and the diffusion of gases in the lungs increase with exercise (energy cost of breathing).

* Pathway through which air passes on its way from the atmosphere to the aveolus:

Nose -> Pharynx -> Larynx -> Trachea -> Bronchus -> Bronchiole

* When breathing in:
- Diaphragm contracts and descends
- Thoracic volume increases
- Pressure decreases
- Rib cage ascends
- Draws air rich in oxygen into the lungs

When breathing out:
- Diaphragm releaxes and ascends
- Thoracic volume decreases
- Pressure increases
- Rib cage descends
- Forces air rich in carbon dioxide out of the lungs

* Ventilation = Tidal Volume x Breathing Rate

Rest: 0.5 L/breath x 12 breaths/min = 6 L/min
Moderate Exercise: 2.5 L/breath x 30 breaths/min = 75 L/min
Vigorous Exercise: 3.0 L/breath x 50 breaths/min = 150 L/min

* The heart comprises four chambers (right atrium, right ventricle, left atrium, left ventricle).

* Right atrium receives deoxygenated blood. Blood passes through the tricuspid (AV valve) to the right ventricle. The right ventricle pumps blood into the pulmonary artery.

Oxygenated blood from the pulmonary vein returns to the left atrium. Blood passes through the bicuspid (mitral) valve to the left ventricle. The left ventricle ejects blood through the aortic (semilunar) valve into the aorta for transport in the systemic circuit. semi formal or casual items to wear for women

* Blood is made up of
- 55 - 60% is plasma, to absorb nutrients and transport hormones such as glucose, amino acids (proteins) and lipids (fats)

- 40 - 45% contains RBCs (transport oxygen and carbon dioxide), WBCs (build defence and immunity) and platelets (blood clotting)

* Acute responses to exercise
- Heart rate (HR): beats per minute (bpm), ranges from 60 - 80 bpm at rest to 180 - 200 bpm at maximal exercise

- Stroke volume (SV): volume of blood pumped per contraction (ml/beat), ranges from 60 - 110 ml/beat) to (120 - 220 ml/beat)

- Cardiac output (Q): total volume of blood pumped by the ventricle per minute, ranges from 5 L/min to 20 - 40 L/min

* Q = SV x HR

* Arterial-venous oxygen difference (a-v O2 difference)

- Arterial blood O2 varies little from its value of 20 ml per 100 ml at rest throughout maximal exercise.

- Mixed-venous blood O2 varies between 12 - 15 ml per 100 ml at rest to a low of 2 - 4 ml per 100 ml throughout maximal exercise.

- At rest, a-v O2 difference is about 5 ml per 100 ml of blood. When the person does moderately intense exercise, the difference increases to as much as 16 ml per 100 ml of blood.

- Increase is caused by increase in cardiac output and the amount of oxygen extracted from the blood into the muscle capillaries.

* Fick equation: vO2 = Q x a-v O2 difference

* Distribution of blood flow

- At rest: 15 - 20% of blood flow (20% = 1000 ml) to skeletal muscle
- During vigorous exercise: 80 - 85% (84% = 21 000 ml) of blood flow to skeletal muscle

* Chronic adaptations to training

- Heart size: increase in mass and volume

- HR: decreases at rest and during submaximal exercise

- SV: increases at rest through to maximal exercise

- Q: remains constant at rest, increases significantly during maximal exercise

- Blood flow: skeletal muscles receive greater blood supply

- Blood volume: increases with endurance training

- RBC: mass of RBC increases with endurance training

* HR, SV, Q and O2 extraction increases with exercise.

* Endurance training leads to increased cardiorespiratory fitness.