Chapter - 7 Physiology & Injuries in Sports Notes

Unit VII Physiology & Injuries in Sports 

Based on Latest CBSE Syllabus

Chapter - 7 Physiology & Injuries in Sports

● Physiological factors determining components of physical fitness 
● Effect of exercise on the Muscular System 
● Effect of exercise on the Cardio-Respiratory System 
● Sports injuries: Classification (Soft Tissue Injuries -Abrasion, Contusion, Laceration, Incision, Sprain & Strain; Bone & Joint Injuries - Dislocation, Fractures - Green Stick, Comminuted, Transverse, Oblique & Impacted) 

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 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.

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.

Sports Injuries

Sports Injuries are the injuries that occur during athletic activities. In Sports and games, it is common to get sports injuries during practice, training, or competition. 

Classification (Soft Tissue Injuries -Abrasion, Contusion, Laceration, Incision, Sprain & Strain; Bone & Joint Injuries - Dislocation, Fractures - Green Stick, Comminuted, Transverse, Oblique & Impacted) 

Classification of Sports Injuries

A. Soft Tissue Injuries

1. Contusion - 
It is a muscle injury. A direct hit can be the cause of Contusion. It can also be caused by minor accidents such as failing, hitting, or kicking. Blood vessels in the muscles are broken in Contusion and bleeding may occur in the muscle which can cause bruises. 
It is common in boxing, kabaddi & wrestling.

2. Abrasion-
It is a key injury that generally occurs due to friction with certain equipment or falling at the area where the bone is very close to the skin. It can be caused by falling on a hard surface. Deep abrasion may cause bleeding.
It can occur in a basketball court, kabaddi, hockey, football etc.

3. Laceration- It is an irregular cut in the skin caused by a sharp object and is more dangerous than incised wounds.

4. Incision- It may occur due to a sharp-edged object. Sometimes, arteries and veins may be cut causing blood to come out freely.

5. Strain - 
It is also a muscle injury. Strain can be mild to severe. It is caused by twisting or pulling a muscle or tendon. In case of complete muscle rupture, it is not possible to move that part and there may be severe pain around the rupture. It can happen suddenly or over days or weeks.
A sudden strain is caused by recent injuries like lifting heaving objects in the wrong way.

6. Sprain- 
It is a ligament injury. It may occur due to overstretching or tearing of ligaments. 
Falling, twisting or getting hit can force a point out of its normal position and can cause ligaments around the joint to tear. Usually, It occurs at the wrist joint and ankle joint.
Common Symptoms of this injury are- swelling, inflammation, server pain and tenderness. 

Prevention of Soft Tissue Injuries
1. Proper warm-up is essential before any sports activity.
2. Proper Conditioning should be done during the preparatory period.
3. Players should be careful and alert during training and competition.
4. Good quality sports equipment should be used.
5. Grounds/Courts should be smooth and clean.
6. Protective equipment should be used.
7. Players should not continue to play during fatigue.
8. The Complete Scientific Knowledge of the game is a must for preventing the sports injuries
9. Balanced Diet and Adequate rest.

B. Bone Injuries

 There are six types of bone injuries. They are-

1. Simple Fracture-
The fracture is without any wound, where the bone is broken in one place.

2. Compound Fracture-
The fracture in which skin and muscles are damaged along with the fracture. Usually, the bone comes out through the skin by tearing it.

3. Complicated Fracture-
A fracture in which a bone breaks and damages the internal organs. These fractures are complicated and dangerous.

4. Greenstick Fracture-
The bone bends whenever there is stress on the bone. Common in children as their bones is delicate.

5. Comminuted Fracture-
A fracture in when a bone is broken into three or more pieces. Possible in a cycle or motorcycle race.

6. Impacted Fracture-
A fracture in which the end of a fractured bone enters into another bone.

Causes of a Fracture

  1. Forceful and unnatural movements.
  2. Sudden fall on a hard surface.
  3. Direct hit or strike with any sports equipment.
  4. High-impact sports events
  5. Prolonged long-distance walking or running.
  6. Osteoporosis


1. A proper warm-up before participating in sports.
2. Proper Conditioning of the body.
3. Protective equipment should be used.
4. Players should not continue to play in a state of fatigue.
5. Calcium and vitamin D deficiency may weaken the bone. So, a balanced diet must be taken.
6. Always be careful and alert while playing.
7. Use good quality Sports equipment
8. Training and Competition area should be clear of hazards.

C. Joint Injuries

Dislocation of joints is the main injury. A hard strike to the joint, or a fall may cause dislocation. 

1. Dislocation of Upper Jaw: Occurs when the chin strikes any object forcefully.
2. Dislocation of Shoulder Joint: Occurs due to a sudden jerk or fall on a hard surface. The end of the humerus comes out of the socket.
3. Dislocation of Hip Joint: Putting maximum strength spontaneously may cause dislocation of the hip joint. The end of the femur is displaced from the socket.
4. Dislocation of Wrist: A miscalculated landing may cause dislocation of the wrist. It occurs when a person uses his hand to break his fall. The Sportsperson who plays the sport in which he may fall, have the risk of getting his wrist dislocated.


  1. A proper warm-up is essential before any physical activity.
  2. The stretching exercise should be included in the warmup.
  3. Proper Conditioning should be done during the preparatory period.
  4. Use Protective equipment/gear as per the requirement of the sports.
  5. Discontinue the practice during fatigue

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