NCERT Solution Class 11 Physical Education Chapter 3: Physical and Physiological Factors of Physical Education and Sports

The terms growth and development are used in various aspects of life. Growth can be explained as becoming bigger or larger. Growth is termed as a physical change, whereas development includes physical, social, and psychological changes. Development also means transformation or improvement. Growth is related to quantitative improvement. Development is related to quantitative as well as qualitative improvement.

Factors affecting growth and development:

The following factors influence the growth and development of a living organism.

(i) Heredity: Heredity is a biological process that plays an important role in the transmission of physical and social attributes from parents to their children. Height, weight and structure of the body, colour of hair and eyes, intelligence, aptitudes, and instincts of the child are highly influenced by heredity.

(ii) Environment: Environment plays an important role in human life. Psychologically a person’s environment consists of the sum total of the stimulations (physical and psychological) which is received from the conception. 

There are three different types of environment, such as— 

1. Physical: It consists of all outer physical surroundings. These are both animate and inanimate which have to be manipulated in order to provide food, clothing, and shelter. Geographical conditions such as weather, climate, and physical environment also have considerable impact on an individual child. 

2. Social: It is constituted by the society, individuals, institutions, social laws, and customs that regulate human behaviour. It refers to the physical and social setting in which a child lives. It includes culture,  education, human settlement, etc. 

3. Psychological: It is rooted in an individual’s reaction with an object and situation. One’s love, affection, emotion, and feeling of friendship and brotherhood will strengthen human bond with one another.

(iii) Gender: Gender acts as an important factor in human growth and development. Boys in general are taller, heavier in comparison to the girls but girls demonstrate early physical growth during adolescence than boys. The body composition and structural growth of girls are different from boys. 

(iv) Nutrition: Growth and development of the child depends on food habits and nutrition. The human body requires an adequate supply of calories for its normal growth and this requirement varies with phases of development. 

(v) Exercise: Physical exercises have positive impact on growth and development of the children. The functional activities come in the form of exercises of the body.

(vi) Hormones: Hormones are chemical substances and play an important role in regulating the process of growth and development. There are many endocrine glands present inside our body. Endocrine glands are ductless glands and are situated in some specific parts of the body. These glands make internal secretions locally and produce one or more hormones.

(vii) Pollution: According to studies, air pollution not only affects the respiratory organs but also has harmful effects on human growth. Indoor pollution or the pollution from housing conditions can result in ill health which can negatively impact human growth and development. For example, lead exposure from deteriorated lead-based paint in older housing can be very harmful.

(viii) Socio-economic Status: Socio-economic factors definitely have some effect. It has been seen that children from different socio-economic background vary in average body size at all ages. The families with high income are primarily more advanced. The most important reasons behind this are better nutrition, better facilities, regular meals, sleep, and exercise.

Difference between growth and development:

Muscle is a tissue which has the power of contraction. Skeletal muscles are the main muscles for physical activities and exercises. Several changes take place in the skeletal muscles depending upon the type of training which an individual is undergoing. 

The effects of exercise on muscular system are summarised as follows:

(i) Muscular hypertrophy: Due to regular exercise, training muscles become enlarged. Muscle fibres, diameter and length increases. The total amount of protein, glycogen and enzymes are increased. 

(ii) Aerobic changes: By training, the amount of myoglobin increases which helps for better supply of O2 to the working muscles of the body. By training, muscles produce energy by increased oxidation of glycogen. A trained muscle uses more fat to supply more energy. 

(iii) Anaerobic changes: These are the changes which help in supply of energy in the absence of O2. 

(a) Increased lactic acid tolerance.

(b) Change in blood flow of the muscles.

(c) Change in red and white fibres of the muscles. 

(iv) Training and capillary supply: Endurance training increases the capillary ratio (expressed as capillaries per fibre). Training increases capillary density as well. 

(v) Influence on performance: As muscles become stronger, they contract with less exertion during a maximum voluntary force. A greater perfusion occurs, and the exercise can be continued without involving the anaerobic metabolism. This would help in delaying the lactic acid accumulation and increase in the muscular force. Strength, flexibility and endurance are increased after the training.

The mechanism of inspiration and expiration is known as respiration. It is controlled by medulla oblongata of the brain. It helps in adequate supply of O2 and elimination of CO2 from the body. 

The effects of exercise on respiratory system are summarised as follows:

(i) Tidal volume: It is referred to as the volume of air inspired or expired per breath. During rest, it is around 500 ml; during exercise it increases; during maximal exercise, it increases 5 to 6 times above the resting values.

(ii) Respiratory rate (F): It is also known as breathing rate or breathing frequency. It is defined as the number of breaths per minute. At rest, it is 12–20 per minute, during exercise it increases to 2–3 times. 

(iii) Minute ventilation or Pulmonary ventilation (PV): It is commonly referred to as the breathing process of lungs during inhalation and exhalation. 

PV = Tidal volume × Respiratory rate 

PV = (TV × RR) 

During rest = 8 litres/minute 

(PV changes with body size, it is smaller in female and larger in male.) 

(iv) During exercise: PV increases during exercising. The initial rise in the ventilation is due to the increased stimulation of the inspiratory centres caused by muscular activity. The second phase of gradual increase in the ventilation occurs due to an increase in the temperature, and chemical changes in the arterial blood produced by muscular activity. 

(v) Pulmonary diffusing capacity: The rate of diffusion of gas between the alveoli of the lungs and the blood of the lung capillaries is called pulmonary diffusing capacity. During exercise the pulmonary diffusing capacity for oxygen increases.

(vi) Hyperventilation: An increased breathing due to an increased tidal volume or increasing respiratory rate or both is referred to as hyperventilation. 

(vii) Total lung capacity: The volume of air in the lungs at the end of maximal inspiration is termed as total lung capacity. During exercise the total lung capacity slightly decreases. 

(viii) Vital capacity: The maximal volume of air which is forcefully expired after maximal inspiration is called vital capacity.

Physical and physiological changes during different developmental stages:

(i) Early Childhood: Early childhood is a time of tremendous growth across all the areas of development. Physically, between birth and age of three, a child typically doubles in height and quadruples in weight. A typical three-year-old might have mastered many skills, including sitting, walking, toilet training, using a spoon, scribbling, and sufficient hand-eye coordination to catch and throw anything. Between three and five years of age, children continue to grow rapidly and begin to develop fine motor skills. By the age of five, most children demonstrate fairly good control of pencils, crayons, and scissors. Physical growth slows down between five and eight years of age, while body proportions and motor skills become more refined. Physical changes in early childhood are accompanied by rapid changes in the child’s cognitive and language development.

(ii) Middle childhood: Middle childhood has not been considered an important stage in human development as compared to early childhood. Physical development during middle childhood is less dramatic than in early childhood or adolescence. Growth is slow and steady until the onset of puberty, when individuals begin to develop at a much quicker pace. The age at which individuals enter puberty varies, but there is evidence of a visible trend—the age at which puberty begins has been decreasing over time. In some individuals, puberty may start as early as at age eight or nine. The onset of puberty differs across gender and begins earlier in females. The cognitive development of middle childhood is slow and steady. Middle childhood is a time when children can gain enthusiasm for learning, and work for achievement can become a motivating factor as children work toward building competence and self-esteem.

(iii) Adolescent: The adolescent years are the second period of accelerated growth. The age between 12 and 18 years is generally considered as ‘adolescence’. Individuals may gain a total of 15–20 centimetres in height and as much as 8–10 kg in weight. The timing of this growth spurt is not highly predictable; it varies across both individuals and gender. In general, females begin to develop earlier than males. Sexual maturation is one of the most significant developments during this time. Females tend to mature at about age thirteen, and males mature at about age fifteen. Adolescence is also an important period for cognitive development.

The full form of MV is Minute ventilation.

 It is the amount of blood pumped out by each ventricle of the heart in one minute. It is the product of stroke volume and heart rate. Endurance training results in increased cardiac output through increased stroke volume. Cardiac output increases directly with increased exercise. 

Cardiac output = Heart rate × Stroke volume 

At rest it is around 5 litre/minute; during exercise the increase may be about 4 to 5 fold.

Muscular hypertrophy refers to an increase in muscle mass. This usually manifests as an increase in muscle size and strength. Typically, muscle hypertrophy occurs as a result of strength training such as weight lifting. 

 The stages of life development are discussed below:

(i) Early Childhood: Early childhood is a time of tremendous growth across all the areas of development. Physically, between birth and age of three, a child typically doubles in height and quadruples in weight.

(ii) Middle Childhood: Middle childhood has not been considered an important stage in human development as compared to early childhood. Physical development during middle childhood is less dramatic than in early childhood or adolescence.

(iii) Adolescence: The adolescent years are the second period of accelerated growth. The age between 12 and 18 years is generally considered as ‘adolescence’. Individuals may gain a total of 15–20 centimetres in height and as much as 8–10 kg in weight.

 It involves rhythmic movements using large muscle groups. The general warm-up should consist of a light physical activity like walking, jogging, stationary bike, skipping, or easy aerobics. It is also beneficial in improving neuromuscular coordination of muscles that results in developing better control on muscles. This warming up in turn increases the body temperature resulting in reduced viscosity in muscle fibres and thus helps in getting better results. Both the intensity and duration of the general warm-up (or how hard and how long), should be governed by the fitness level of the participating athlete. 

 It consists of specific exercises which are matched to the main activity. In specific warm-up, some special sets of exercises need to be performed which have a direct relation with the activity to be carried out. In this part, the athletes are specifically preparing their body for the demands of their particular sport. During this part of the warm-up, more vigorous activity should be employed. Activities should reflect the type of movements and actions which will be required during the sporting event. The set of activities and exercises in specific warming up differ from sport to sport. These are especially designed to meet the requirement of different activities and sports.

1.  Growth refers to the process through which body increases size and shape.  

2. There are following major factors which directly or indirectly influence the growth and development of a living organism. 

3. Hormones play an important role in regulating the process of growth and development.

4.   An increased tidal volume, or increased respiratory rate, or both is referred to as hyperventilation. 

5.  Heart rate increases during submaximal exercise and it is caused due to increase in sympathetic nervous system activity.

6. Speed with high velocity movement develops exploring strength or power.