CBSE Class 12 Physical Education Notes Chapter 8 Physiology and Sports is part of Physical Education Class 12 Notes for Quick Revision. Here we have given NCERT Physical Education Class 12 Notes Chapter 8 Physiology and Sports.
Physical Education Class 12 Notes Chapter 8 Physiology and Sports
In physiology, we study how our organs, systems, tissues, cells and molecules within cells work and how their functions are put together to maintain our internarenvironment. “Physiology is the study of how the human body functions.” Physiology is very essential to understand how to attain physical fitness in order to enhance the performance in sports
Gender Differences In Physical Physiological Parameters
|Lean Body Mass||Less||More|
|Strength||Stronger due to greater muscle mass||Less muscle mass|
|Endurance||High due to more hemoglobin and VO2||Less|
|Coordination and Agility||Less||More|
|Muscle Composition||More||Less 1|
|Bones and Ligaments||Longer, stronger but poor balance||Less stronger|
|Attachments||but better balance|
|Cardiac Output||Better cardiac output||Lower cardiac output|
|Respiratory Function||Better due to more haemoglobin||Lack in certain parameters|
|content and VO2|
Physiological Factors Determining Components of Physical Fitness
To understand the physiological factors, the components have to be understood.
The components of physical fitness are as follows
- Muscular Strength One of the basic requirements for success in all movements is muscular strength. It may be defined as the maximum force or tension a muscle or a muscle group can exert against a resistance. The development of strength is specific to the muscle or muscles involved in a particular activity.
- Power Power is the ability of the body to release maximum muscle contraction in the shortest possible time.
- Speed It is the rapidity with which one repeats successive movements of the same pattern. It may also be defined as the ability of a person to move quickly through a short distance.
- Muscular Endurance It may be defined as the ability of a muscle or muscle group to perform repeated contractions against a resistance / load or to sustain contraction for an extended period of time with less discomfort and more rapid recovery.
- Agility It is the ability of the person to change direction while moving at or near full speed. More specifically, agility is the ability of a person to change direction or body position quickly (as fast as he can) and regain body control to proceed with another movement.
- Flexibility In general, flexibility is that quality of the muscles, ligaments and tendons that enables the joints of the body to move easily through a complete range of movement.
- Size of the Muscle The size of the muscle determines the strength possessed by an individual. Males have bigger and larger muscles due to which they have more strength than females.
- Body Weight There is a positive correlation between body weight and strength among international weightlifters. So people who weigh heavier are stronger and have more strength than people who are lighter.
- Muscle Composition Muscles consist of two types of fibres i.e. fast twitch fibres (white fibres) and slow twitch fibres (red fibres).
- Intensity of the Nerve Impulse A muscle consists of many motor units. The number of contracting motor units determines the total force.
- Metabolic Power The metabolic power depends upon the energy supplied through certain enzymes.
- Aerobic Capacity The ability of a person to maintain adequate supply of oxygen to the working muscles influences the endurance.
- Joint Structure The joint structure of a person determines the range of motions and hence level the flexibility of an individual.
- Age and Gender The age of a person as well as the gender determines the level of flexibility. Flexibility decreases with advancement of age and females are more flexible than males.
Effects of Exercise on Cardiovascular System
It has been observed that physical exercises affect the various parameters of the cardiovascular system in many ways. Effects of exercise on the cardiovascular system are
- Cardiac Output It is the amount of blood pumped by the heart in one minute. In other words, it is the product of stroke volume and heart rate. Cardiac output increases with the intensity of the exercises. At rest it is 4 to 6 L/min and during exercises it is 20 to 40 L/min.
Cardiac output = heart rate x stroke volume=
- Heart Rate The number of cardiac contractions in one minute is called heart rate.. Generally normal adult heart rate is 72 beats/min: During exercises the heart rate goes up.
- Stroke Volume The amount of-blood pumped into the aorta with every heartbeat is known as the stroke volume. In an untrained male, it is 70 – 90 mL/beat. In a trained.male athlete, it may be 100 – 120 mL/beat. The stroke volume increases in response to the intensity of the exercises.
- Blood Flow Exercise increases the blood volume caused by a 12% increase in the plasma volume and a slight increase in the red blood cells volume. With increasing intensities of exercise, a . greater accumulation of lactic acid and the production of other metabolic end products (potassium, phosphate) occurs. This increases blood flovy in the cardiac output, while it decrease in kidneys and abdomen.
Effects of Exercise on Respiratory System
Many parameters of respiratory system get affected due to exercises. Effects of exercise on respiratory system are
- Lung Volume With endurance training, lung volume and lung capacity increase. Vital capacity, which is maximal volume of air forcefully expelled is increased after endurance training.
- Breathing Frequency Breathing frequency is the number of breaths per minute. After training, breathing frequency or respiratory rate is decreased.
- Maximum Minute Ventilation Minute ventilation is the amount of air which is inspired or expired in one minute. After training, maximum, as well as minute ventilation is increased.
- Tidal Volume Tidal volume, which is the amount of air inspired or expired per breath, is – also increased as a result of endurance training,
- Ventilatory Efficiency With physical exercises, particularly endurance training, our ventilatory efficiency increases.
- Pulmonary Diffusion Pulmonary diffusion is the exchange of gases taking place in the alveoli (small air sacs in our lungs).
Effects of Exercise on the Muscular System
The effects of exercise on the muscular system are as follows
- Increase in Blood Flow The volume of blood flow to muscle tissues increases during exercise. It can increase by upto 25 times – during specially demanding exercise:
- Respiration During exercise, muscles repeatedly contract and relax,.using and requiring energy to do so. The energy comes from the chemical ATP that-is. broken down during exercise into another chemical called ADP. When there is plenty of oxygen available in the muscle tissues, the energy for muscle action is prpduced aerpbically so muscles get more oxygen.
- Muscle Size Although muscle size (and other physical characteristics such as height) is largely determined by a person’s genes but muscle size also gets affected by the intensity of exercises.
- Blood Supply (to and through muscles) As a result of frequent exercise over a sustained period of time, both the quantity of blood vessels and the extent of the capillary beds increases.
- Muscle Coordination Frequent exercise and specially use of specific muscles for the same or similar skilled tasks.
- Muscle Biochemistry Many beneficial biochemical changes take place in muscle tissues as a result of regular long-term exercise such as increase in the size and quantity of mitochondria in the cells, increase in the activity of enzymes.
Long -Term Effects of Exercises
Exercises are good for the overall well-being of a person. The long-term effects of exercises are as follows
- Increase in Heart Size
- Increase in Heart Rate
- Increase in Stroke Volume
- Decrease in Cholesterol Level
- Increase in Number and Efficiency of Capillaries
- Reduced Risk of Heart Diseases
Physiological Changes Due to Ageing
Some of the physiological changes accompanying the ageing process are
- Muscle Size and Strength As an individual gets older, there is a decline in muscle size. It is believed that this decline is due in part to a reduced amount of protein as well as a decline in the number and size of muscle fibres. As people get old, there is also a parallel decrease in the muscular strength.
- Accumulation of Body Fat With advancing age, there is a general trend to increase the accumulation of body fat. First of all, with advancing age there is a decrease in one’s ability to release or mobilise stored fatty acids from adipose tissues for energy.
- Respiratory System There is good evidence to indicate that pulmonary function is impaired with advancing age. The uptake and exchange of oxygen reduces.
- Cardiovascular System A number of studies have shown that as individuals get older, their overall heart size becomes, smaller. The left ventricular cavity may especially decrease in size as a result of reduced activity and the reduced physical demands of increased age.
- Nervous System The nervous system is responsible for reactions and movements. The brain’s weight, network of the nerves and blood flow decrease with age due to which the reaction time and movement time also slows down.
- Bone Density Bone density decreases with increasing age, which means that elderly people (especially those over 40 years of age) are much more prone to bone injury than young people whose bones have reached full growth and maturity.
Role of Physical Activity in Maintaining Function Fitness in Aged Population
Regular exercises are good to improve the efficiency of the body. It delays the onset of fatigue, develops fitness levels and increases endurance. Regular physical activity keeps the human body livelier, fitter and in better condition for long years before any ageing sets in. Ageing is not a sudden, dramatic occurrence; rather it is a slow process that prolongs over several decades. This process can be delayed with regular physical activity.
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