Physical Education Chapter 8 Notes - Class 12 - Physiology and Sports

Physiology and Sports


Physiological factors Determining the Component of Physical fitness

Components of Physical Fitness are Strength, speed, endurance. Flexibility, etc.

Physiological Factors determining Strength

1. Size of the Muscle- The strength of muscle largely depends on the size of the muscles.
     ⁍ Bigger and larger muscle can produce more force. Males have larger and bigger muscles in comparison to female. 
     ⁍ With the help of different methods of strength training like weight training, the size of strength can be increased and thereby strength can be improved.

2. Muscle Composition- Each Muscle consists of two muscle fibres- i.e., Fast twitch fibres (white fibres) and slow-twitch fibre (red fibres). The fast-twitch fibre is capable to contract faster and can produce more force while slow fibre is capable to contract for a longer duration.
      The muscle with more percentage of fast-twitch fibre can produce more strength. The percentage of fast-twitch fibre and slow-twitch fibre is genetically determined.

3. Body Weight- The individual who is heavier is generally stronger than the individual who is lighter.

4. Intensity of nerve Impulse- When a stronger nerve impulse from central nervous system excites more number of motor units, the muscles will contract more strongly or it can be said that the muscle will produce more force or strength.

Physiological Factors determining Speed

1. Muscle Composition- Muscle with greater no. of fast-twitch fibres contract with more speed than slow-twitch fibres.

2. Mobility of the nervous system- Rapid contraction and relaxation is made possible because of fast excitation and inhibition of concerned motor centres. This is called mobility of the nervous system. 
     ⁍ The mobility of the nervous system is determined by genetic factors and cannot be improved by training.

3. Explosive Strength- Explosive strength is important for fast and explosive movement. 
     ⁍ It depends on muscle composition, muscle size, muscle coordination and metabolic process. 
     ⁍ Except for Muscle composition, the remaining factors can be improved through training.

4. Flexibility- good flexibility allows maximum range of movement with minimum internal resistance.

5. Bio-chemical reserves and metabolic power determine the speed- For doing the exercises which are done quickly muscles need more energy. This energy in our muscles is obtained through the presence of ATP (Phosphagen adenosine triphosphate) and creatine phosphate (CP). 
     ⁍ The percentage of power and quantity in ATP and CP can be increased through training.

Physiological Factors determining Endurance

1. Aerobic Capacity- To work continuously by the muscle, energy is required which is supplied by the presence of oxygen. The aerobic capacity depends upon-
   a. Oxygen intake- the amount of oxygen taken by lungs from the atmosphere. More amount is better for achieving higher VO2 max.
   b. Oxygen Transport- The oxygen transported depends on the amount of oxygen absorbed by the blood from the lungs & the ability of the circulatory system to carry this quickly to working muscles.
   c. Oxygen Uptake- The amount of oxygen that can be absorbed and consumed by the working muscles from the blood is called oxygen uptake.
   d. Energy Reserves- The aerobic capacity depends upon the muscle glycogen and sugar level in the blood. If Muscle glycogen falls below a certain level, fatigue occurs.

2. Lactic Acid Tolerance- The ability to tolerate a higher concentration of lactic acid is an important factor in determining anaerobic capacity. It is important for activities that last for 40 seconds or more. 
     ⁍ Can be improved through training.

3. Muscle Composition- Slow-twitch fibre is best used for endurance activities (Aerobic activities). They produce a small level of forces for a longer time and that’s why better suited for endurance activities.

4. Movement Economy – Economical movement is important in endurance activities. 
     ⁍  The runner who can run at the same pace with less energy expenditure can run for the same speed for a longer distance. 

Physiological Factors determining Flexibility

1. Muscle Strength – the muscle should be at the minimum level of strength to make movement possible especially against gravity or external forces. In sprint sports, the legs or knees cannot be lifted to certain heights or angle if the related muscles are weak.

2. Age and gender- Flexibility decreases with an increase in age. However, flexibility can be improved with the help of training. 
     ⁍ Females tend to have better flexibility than male. 

3. Joint structure- Some joints have a greater range of movements than others in our body.

4. Stretchability of muscles- for making movement at the joint, the muscle needs to contract to execute the movement. If the muscles are not regularly stretched, they tend to get shorter and restricts the range of movement
     ⁍ The stretchability of muscle is trainable.

5. Internal Environment: influences the athlete flexibility.

6. Previous injury- Injuries to the connective tissue and muscles lead to thickening or fibrosing of the muscles. 
     ⁍ Fibrous tissues are less elastic and reduce flexibility.

Effects of exercise on the Cardiovascular System

A. Immediate effect of exercise

1. Increase in heart rate- The resting heart rate in an adult is 72 beats per minute. Even before doing exercise heart rate increases in anticipation, this is called anticipatory response. 
     ⁍ When exercising the heart increases depending on the intensity and duration of the exercise.
2. Increase in stroke volume- Stroke volume is the amount of blood ejected per beat from the left ventricle (Measured in ml/beat). 
     ⁍ Stroke volume increases with an increase in the intensity of exercise. 

3. Increase in cardiac output- Cardiac output is the amount of blood pumped by the heart in one minute. (Measured in litre/minute). It is the product of stroke volume and heartbeat. 
     ⁍ If either heartbeat or stroke volume or both increases the cardiac output increases too. 

4. Increase in blood flow- Generally, at rest, 15%-20% of the blood is supplied to skeletal muscles. 
     ⁍ It increases to 80-85% of cardiac output during an intense workout.

5. Increase in blood pressure: while doing the exercise.

B. Long term effect of exercise

1. Increase in size of heart- The muscles of the heart increase in size and strength with regular exercise. 
     ⁍ The heart walls grow stronger and thicker.

2. Decrease in resting heart rate- After regular exercise, the heartbeat becomes more efficient.

3. Stroke volume increases at rest- The stroke volume remains up to 50-70 ml/beat in untrained individual and 70-90 ml/beat in trained individuals.

4. Regular exercise tends to increase cardiac output.

5. There is an increase in blood flow in the body.

6. There is a decrease in blood pressure – by 10 mmHg at rest.

7. Increase blood volume- blood produces a greater number of RBC in order to keep muscles supplied with oxygen during heavy exercise.

8. Quicker recovery rate- heart rate and rate of respiration become normal rapidly.

9. Reduced risk of heart diseases.

Effects of exercise on Respiratory System

1. Decrease in rate of respiration at rest.

2. Strengthens diaphragm and muscles.

3. Regular exercise increases willpower.

4. Increase in endurance.

5. Regular exercise Increases tidal air capacity- tidal air is the amount of air that flows in and out of lungs in each quiet respiratory movement.

6. Increase in size of chest and lungs- when a person performs regular exercise, he/she requires more amount of oxygen. 
     ⁍ He inhales more amount of oxygen during exercise. Consequently, his chest and lungs are exercised. After some time period the size of the chest and lungs increases.

7. Increase in vital air capacity- It is the amount of air which an individual can inhale and exhale with maximum effort. With regular exercise the persons capacity increases to 5500cc.

8. Prevention from diseases- if we perform regular exercise, we will inhale and exhale more air speedily. By doing so, the waste product will never stick to our lungs. These products will come out automatically and lungs will not be damage. This way, we can prevent various diseases.

9. Avoids second wind- a person who does regular exercise hardly feels second wind (the ability to breathe freely after having been out of breath)

10. Unused alveolus becomes active- because much amount of o2 is required in vigorous and prolonged exercises.

Effects of exercise on Muscular System

1. Change in shape and size of muscles- Cells of muscles are enlarged which change the shape &  size of muscles.

2. Muscles remain in tone position; when exercising on the regular basis.

3. Delay’s fatigue- Fatigue is due to the formation of carbon dioxide, lactic acid and acid phosphate. 
     ⁍ The accumulation of these become less in individual who exercise daily.

4. Reduce reaction time- Speed of nerve impulse increases which ultimately improves the reaction time.

5. Body postures remain correct- Muscle strength increases which in turn keeps the body in the correct position.

6. Formation of more capillaries- New capillaries are formed for better and efficient blood circulation.

7. Controls extra fat- Exercises burn the extra calories deposited in the form of fat.

8. Connective tissue becomes powerful.

9. Movement of muscles become efficient and smooth.

10. Increase in food storage.


Note: These notes are for revision purposes and that why not all point are explained briefly. the point which is cleared is not briefed. 

The notes are very precise and are strictly based on the CBSE Syllabus to help you to revise all points in the least amount of time. While being precise these notes don't leave any important point.

So, these were the notes of chapter 8 of physical education class 12 strictly based on the latest CBSE syllabus.

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