Physiology and Injuries in Sports Class 12 Notes

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Understanding how the human body responds to physical activity is essential for every sportsperson. In Class 12 Physical Education, the chapter 7 “Physiology and Injuries in Sports” explores the effects of exercise on our body systems and the types, causes, and prevention of sports injuries.

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Physiological Factors Determining the Component of Physical Fitness

Exercise helps the body system to stay strong and healthy. Some of the important body systems are the skeletal, muscular, nervous, endocrine, cardiovascular, metabolic, respiratory, digestive, urinary and reproductive systems. All the systems work together, but the responses of these systems are independent. Here we will study three major physiological factors that determine the various components of fitness.

Skeletal Muscles Factor

Skeletal muscles are made up of muscle fibres, which are divided into two categories: Type 1 (slow-twitch fibres) and Type 2 (fast-twitch fibres). Both muscles having different working styles and training can change the balance between slow and fast twitch fibres.

  • Slow Twitch Fibres (Type I); The slow-twitch muscles do not move fast, but they can keep working for a long time. This muscle helps in running, swimming and cycling. This type of muscle uses a lot of oxygen, so that’s why they look red.
  • Fast Twitch Fibres (Type II): The fast-twitch muscles work fast but tire quickly. This type of muscle helps in jumping, sprinting and throwing. These muscles do not need much oxygen, so that’s why they look lighter in colour. These muscles give quick bursts of energy.

Energy Production Factor

Our body needs energy to do activities in day life and in physical activities like running, jumping or playing sports. The sources of these energies are food and the body. Use these energies three different ways:

  • Quick Energy (ATP-CP System): It is a short-time energy for the activity (less than 10 seconds); it is helpful in jumping, throwing or weightlifting. Creatine Phosphate (CP) energy is stored in muscles.
  • Medium-Length Energy (Anaerobic System): It is moderate energy, less than 2 minutes. This energy is helpful in a 200m or 400m race or in fast movements. This energy uses glucose to create energy without oxygen.
  • Long-Term Energy (Aerobic System): It is a long-activity type of energy for more than 2 minutes. This energy is helpful in the time of a marathon run, football, cricket, etc. This energy uses oxygen to burn carbohydrates and fats.

Cardiorespiratory Factor

The Cardiorespiratory System is a combination of the heart (cardiovascular system) and lungs (repiratory system). This system work together to provide oxygen to muscles and helps to remove waste product during exercise.

How It Works During Exercise

  • The lungs take oxygen and this oxygen enters to the blood.
  • The heart pumps oxygen to muscles for energy production.
  • This energy helps the muscles for physical activity.

Effect of Exercise on Muscular System

Exercise affects the muscles in two different ways: short-term (immediate effects) and long-term (lasting adaptations).

Short-Term Effect of Exercises on Muscular System

  • Increased Blood Supply: More blood flow will help to deliver more oxygen and nutrients to muscles.
  • Increased muscle temperature: Muscles generate heat energy during physical activity, which raises body temperature.
  • Increased muscle flexibility: Higher blood flow increases muscle flexibility and improves movement.
  • Accumulation of Lactate: If muscles don’t get enough oxygen, then lactic acid will build up, which will affect the performance.
  • Micro-tears in Muscle Fibres: When you exercise, your muscles work hard, and that breaks the muscle fibres. Your body repairs these tears by adding more muscle proteins.

Long-term effects of exercise on the muscular system

  • Hypertrophy of Muscle: Over time, muscles increase in size and strength due to physical exercise.
  • Increase in Strength of Ligaments and Tendons: Regular exercise reduces injury risks.
  • Increase in Size and Number of Mitochondria: Exercises increase the number and size of mitochondria, which will boost energy production.
  • Increase in Myoglobin Storage: More myoglobin stores oxygen, which will improve the performance.
  • Increase in Glycogen Storage: Muscles store more glycogen, which will be helpful for extending energy availability for 90 – 120 minutes.
  • Increase in Oxidation/ Metabolism: Exercise enhances fat oxidation, which will be helpful for long-lasting energy.
  • Increase in Lactate Acid Tolerance: Regular exercise helps muscles handle lactic acid, which will reduce pain and fatigue.

Effect of Exercise on Cardiorespiratory System

The cardiorespiratory system consists of two parts. Cardiovascular System and Respiratory System.

Cardiorespiratory system
  • Cardiovascular system: it consists of three parts – heart, blood vessels and blood. Its major functions are to deliver oxygen and nutrients, remove CO₂ and other metabolic waste products, and transport hormones and other molecules. The cardiovascular system controls the body fluid balance and regulates immune function.
  • Respiratory system: The important parts of the respiratory system are the nose, nasal cavity, pharynx, larynx, trachea, bronchi, and lungs. Its major functions include transporting air to the lungs, exchanging gases (O₂ and CO₂) between the air and blood, and regulating blood pH.

Short Term Effects of Exercise on Cardiovascular System

Exercise immediately impacts the cardiovascular system due to an increase in heart function and blood circulation.

  • Increase Heart Rate: Exercise makes the body work harder, and therefore muscles require more oxygen to continue to work effectively.
  • Increase Blood circulation: As the heart rate increases, blood circulation increases in the body to deliver the oxygen to muscles.
  • Increased Blood Pressure: Endurance exercise leads to an increase in systolic blood pressure, which is in direct proportion to the increase in exercise intensity.
  • Increase Stroke Volume: The volume of blood pumped during one beat (contraction) is called stroke volume. During exercise, stroke volume increases as more oxygen is required.
  • Increase Cardiac Output: Cardiac output is the amount of blood pumped out by each ventricle of the heart in 1 minute. It is the product of the heart rate (HR) and the stroke volume (SV). Resting cardiac output is approximately 5.0 L/min but differs according to the size of the person.

Long Term Effects of Exercise on Cardiovascular System

  • Increased Size and Strength of Heart: Continuous aerobic exercises help to increase the strength and the size of heart which helps in better performance.
  • Low Level of Accumulation of Lactic Acid: Regular exercises prepare muscles to adjust to working with lower levels of oxygen and the circulatory system develops itself to transport oxygen to different parts of the body, thereby resulting in low levels of lactic acid.
  • Decrease in Resting Heart Rate: Due to improved efficiency of the heart, it is required to pump less blood to meet the needs of the body. As a result, the heart rate at rest decreases.
  • Normal Blood Pressure: Regular exercise helps keep the blood pressure normal.
  • Increase in Stroke Volume and Cardiac Output: Since the size and strength of the heart increases, heart pumps blood more efficiently with increase in stoke volume and cardiac output.
  • Increase in Capillaries Network: To achieve the demand for oxygen, capillaries network increases. Due to the demands placed on different parts of the body during exercise, the capillary density at muscle sites improves. Increased capillary density allows for greater oxygen being transported to the muscles, improving their ability to perform intense exercise.

Effect of Exercise of Respiratory System

Short Term Effects of Exercise in Respiratory System

  • Respiratory Rate Increases: The normal respiration rate for an adult at rest is 12 to 20 breaths per minute, but during exercise it increases to 40 breaths per minutes.
  • Tidal Volume Increases: The amount of air inhaled and exhaled in one breath is known as tidal volume. Tidal volume increases as a result of exercise to take in more oxygen and remove carbon dioxide from our body.
  • Rate of Exchange of Gas Increases: Regular exercise increases the rate of exchange of gas in lungs.

Long Term Effects of Exercise in Respiratory System

  • Increased Efficiency of Respiratory Muscles: Due to regular exercise efficiency of respiratory muscles increases, inhalation and exhalation become fluent. This helps to meet the demand of oxygen.
  • Increased Lung volume: Continuous exercises done for long duration help to increase the capacity and volume of lungs. Vital capacity increases almost 100 % as compared to that of a normal individual.
  • Increased Pulmonary Diffusion: Pulmonary Diffusion refers to the capacity of the lungs to allow oxygen and carbon dioxide to pass in and out of the blood. Regular sub-maximal exercise training develops the scope of increasing the exchange of gases, and in this process the size of the alveoli also increases.
  • Increased Residual Volume: Residual volume is the volume of air that remains in the lungs after forceful expiration. Regular exercise increases residual volume that helps to exchange the gases in normal limits.

Physiological Changes Due to Ageing

When the people get older, their body changes naturally due to ageing in the body. Ageing is a natural process that affects organ systems and tissue over time. It mainly happens due to genetics, diet, exercise and environmental factors, etc.

Physiological Changes Due to Ageing
  • Muscles become weaker: in the age of 20 to 40, the muscular strength is at its peak, and after the age of 40, the muscular strength gradually declines. Men lose strength faster than women. Between the ages of 25 and 80, muscle mass can reduce by 40% to 50% due to muscle fibre loss.
  • Nerve Function Slows Down: The brain and nerves control the body movement; ageing slows down nerve signals, which will make reaction time slower.
  • Hormone Levels Drop: Some of the hormones decrease in the body and affect metabolism. In this age sugar control gets weaker, which will increase the risk of diabetes. Thyroid hormones slow down energy levels.
  • Lungs get less efficient: In this time, the breathing becomes harder, and lung capacity reduces. Due to this, less oxygen reaches muscles, which will affect the body activities.
  • Heart Works Less Efficiently: At this age the heart rate and blood circulation slow down, and less oxygen reaches muscles, which will affect stamina.
  • Body Fat Increase: At this age the fat percentage goes up and muscle mass goes down after age 60.
  • Bones Become Weaker: At this age, bone density reduces; women are at more risk of bone loss compared to men.

Sports Injuries

A sports injury is any damage to the body tissues, bones or muscles during the physical activity. It can result in pain and stop a person from continuing their activity.

Definition

According to Morris (1984), “some physical damage or insult to the body that occurs during athletic practice or competition causing a resultant loss of capacity or impairing performance.”

Classification of Sports Injuries

  • Direct Injuries: It happens when a player gets hit with another player or due to equipment.
  • Indirect Injuries: It happens during the exercise when a muscle, ligament, or tendon gets damaged due to sudden twist or overuse.
  • Soft Tissue Injuries: Soft tissue injuries affect muscles, skin and ligaments.
  • Hard Tissue Injuries: They affect bone fractures or dislocation.
  • Overuse Injuries: When athletes use bad techniques due to this stress on muscles, bones or joints.

Physical Education Class 12 Notes 

Physical Education Class 12 Questions and Answers


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