Physiological adaptations are the changes that occur within specific body organs and tissues during exercise
The increased demand of oxygen and nutrients required during exercise dictates the bodies physiological changes.
The important responses to training are related to;
- Heart Rate
- Ventilation Rate
- Stroke volume
- Cardiac Output
- Lactate Levels
- Heart rate increases with exercise. Heart rate increases are related to the intensity of the exercise
- When exercise commences and for the first 5-10 minutes there is a sharp rise in Heart Rate.
- In a fit or trained person the "steady state" is achieved and a plateau is achieved if the activity is moderate intensity.
- For an unfit or untrained person the Heart Rate continues to rise steadily as the exercise continues.
- Post exercise the Heart Rate declines rapidly followed by a slower decline to return to the pre-exercise levels. The trained person will experience a much quicker return to pre-exercise levels compared to the unfit person whom may take hours to recover.
- Heart Rate is a good indicator of the intensity of exercise and the efficiency of the Cardiovascular system.
- Two phases; inspiration and expiration
- Usually 6 litres of air breathed per minute
- At rest VR is about 12 breaths per minute equal to 500 ml per breath.
- VR increases with and just prior to exercise.
- Rate and depth is increased
- VR remain higher for short period after exercise stops before steadily declining to return to rest levels.
Stroke volume is the amount of blood being pumped out of the left ventricle during a contraction (ml/beat)
- SV increases with with exercise.
- Increase is rapid initially
- A Fit person has the potential for a SV of 160ml/beat at sub max intensity
- An unfit person will achieve only 60-80 ml/beat.
- the Fit person has a greater SV at rest and during exercise
Cardiac Output (CO) = Heart rate (HR) x Stroke Volume (SV)
- The working muscles' demand more oxygen causing a change in the distribution of blood in the body.
- Working muscles can demand up to 84% of blood flow.
- Comparing the trained and untrained athlete:
- At rest and sub maximal intensity: the CO is similar due to the trained having a lower rest HR but higher SV.
- At maximal: the main difference occurs with the trained person able to produce up to double the CO of the untrained person.
- Lactic acid is the by product of the breakdown of carbohydrates in muscles to form energy (ATP)
- When Lactate forms so does an acidic H+ ion increasing the acidity of the blood.
- When abundance of oxygen is present the acid is removed as (H2O)
- When intensity increases and the Oxygen demands aren't met the acid build up prevents muscles contracting efficiently.
- This is known as the Lactate inflection point (LIP) . LIP is about 80% to 90% of MHR in trained athletes, much lower in the untrained.
- When LIP is reached is when fatigue occurs in the athlete. causing a reduced performance or end of exercise.
Lactate Levels
Ventilation Rate
The total volume of oxygen breathed into the lungs per minute.
Cardiac Output
- Cardiac output increases in response to exercise similarly to Stroke volume.
Immediate Physiological Response to training
Stroke Volume
Questions
Answer the following:
1,Explain how the heart rate responds to an increase in exercise?
2,Explain why ventilation rates rise with increase in exercise intensity?
3,Outline the differences in Stroke Volume and Cardiac output? Why might the the levels be different in trained and untrained athletes?
4,Explain the effect of increased lactate levels on performance?
Heart Rate
Immediate Physiological Response to Training