UGC NET Physical Education Subject -II Syllabus

What are the two principal classifications of muscle fibre types?

Type I (slow-twitch, slow oxidative) and Type II (fast-twitch), with Type II subdivided into Type IIa (fast oxidative-glycolytic) and Type IIx/IIb (fast glycolytic).

Compare slow-twitch (Type I) and fast-twitch (Type II) muscle fibres.

Type I: slow contraction, high mitochondria/capillary density, fatigue-resistant, aerobic, red, suited to endurance. Type II: fast contraction, low oxidative capacity, fatigue quickly, anaerobic/glycolytic, white (IIx), suited to power and speed.

Which fibre type predominates in elite marathon runners versus elite sprinters?

Marathon (endurance) runners have a high proportion of Type I slow-twitch fibres; sprinters have a high proportion of Type II fast-twitch fibres.

What muscular adaptations result from resistance (strength) training?

Muscle fibre hypertrophy (increased cross-sectional area), increased myofibrillar protein and contractile proteins, increased anaerobic enzyme activity, and neural adaptations such as greater motor unit recruitment.

What muscular adaptations result from endurance (aerobic) training?

Increased mitochondrial number and size, increased oxidative enzyme activity, increased myoglobin content, increased capillary density, and enhanced fat utilization, mainly in Type I fibres.

Distinguish muscle hypertrophy from hyperplasia.

Hypertrophy is an increase in the size (cross-sectional area) of existing muscle fibres; hyperplasia is an increase in the number of fibres through fibre splitting (rare in humans).

What is the neuromuscular junction?

The neuromuscular junction is the synapse between the terminal of a motor neuron and the motor end-plate of a muscle fibre, where a nerve impulse is transmitted to the muscle.

Which neurotransmitter is released at the neuromuscular junction and what is its action?

Acetylcholine (ACh); it binds receptors on the motor end-plate, opening ion channels to depolarize the sarcolemma and generate an action potential in the muscle fibre.

Describe the transmission of a nerve impulse across the neuromuscular junction.

The nerve impulse triggers $\ce{Ca^{2+}}$ influx into the axon terminal, releasing acetylcholine into the synaptic cleft; ACh binds end-plate receptors causing depolarization, then acetylcholinesterase breaks down ACh to end the signal.

What is a motor unit?

A motor unit is a single motor neuron together with all the muscle fibres it innervates; it is the functional unit of muscle contraction.

Define the 'all-or-none' law of muscle contraction.

When stimulated at threshold or above, an individual muscle fibre (or motor unit) contracts maximally; below threshold it does not contract at all — there is no partial response.

What are kinesthetic (proprioceptive) sense organs?

Specialized sensory receptors that provide information about body position, movement, muscle tension, and joint angle, including muscle spindles, Golgi tendon organs, and joint receptors.

Compare the functions of the muscle spindle and the Golgi tendon organ.

The muscle spindle detects changes in muscle length and rate of stretch, triggering the stretch reflex; the Golgi tendon organ detects muscle tension and protects against excessive force by causing reflex relaxation (inverse stretch reflex).

How does the nervous system exert neural control of motor skills?

Through coordinated action of the motor cortex (planning and initiation), cerebellum (coordination, timing, balance), basal ganglia (movement regulation), spinal reflexes, and proprioceptive feedback for refined, skilled movement.

What is meant by the biochemical aspects of exercise?

The study of the chemical reactions and energy transformations — especially ATP production and breakdown of carbohydrates, fats, and proteins — that supply energy for muscular work.

What is the immediate energy currency for muscular contraction?

Adenosine triphosphate (ATP); its hydrolysis releases energy: $$\ce{ATP + H2O -> ADP + P_i + energy}$$

Describe the metabolism of carbohydrates as an energy source.

Carbohydrates are broken down to glucose, which undergoes glycolysis to pyruvate; aerobically pyruvate enters the Krebs cycle and electron transport chain, and anaerobically it is converted to lactic acid.

Describe the metabolism of fats during exercise.

Triglycerides are broken down (lipolysis) into glycerol and free fatty acids; fatty acids undergo beta-oxidation to acetyl-CoA, which enters the Krebs cycle, yielding large amounts of ATP aerobically.

How are proteins used in energy metabolism?

Proteins are broken into amino acids which can be deaminated and converted (via gluconeogenesis or directly) into intermediates for the Krebs cycle; they contribute minimally (about 5-10%) to energy, mainly during prolonged exercise.

Name the three energy systems supplying ATP for muscular work.

The ATP-PC (phosphagen) system, the anaerobic glycolytic (lactic acid) system, and the aerobic (oxidative) system.

Describe the ATP-PC (phosphagen) energy system.

An immediate anaerobic system in which phosphocreatine is broken down to rapidly resynthesize ATP: $$\ce{PC + ADP -> ATP + creatine}$$ Lasts about 8-10 seconds; fuels short, explosive efforts.

Describe the anaerobic glycolytic (lactic acid) system.

Glucose/glycogen is broken down without oxygen to produce ATP and lactic acid; it provides energy for high-intensity efforts lasting roughly 30 seconds to 2 minutes and yields a net 2 ATP per glucose.

Describe the aerobic (oxidative) energy system.

Using oxygen, carbohydrates and fats are fully oxidized via glycolysis, the Krebs cycle, and the electron transport chain, producing large amounts of ATP for prolonged, low-to-moderate intensity activity, with $\ce{CO2}$ and $\ce{H2O}$ as by-products.

How much net ATP is produced from the complete aerobic oxidation of one glucose molecule?

Approximately 36-38 ATP (commonly cited as 38) per molecule of glucose, compared with a net 2 ATP from anaerobic glycolysis.

What is the energy systems' contribution at rest versus exercise?

At rest the aerobic system predominates using mainly fat. During exercise contribution shifts toward carbohydrate and anaerobic systems as intensity rises; brief high-intensity work relies on ATP-PC and glycolysis.

What is direct calorimetry for measuring energy cost of exercise?

A method that measures energy expenditure directly by measuring the heat (in a sealed insulated chamber) produced by the body, since all metabolic energy ultimately appears as heat.

What is indirect calorimetry for measuring energy cost of exercise?

A method that estimates energy expenditure by measuring oxygen consumption and carbon dioxide production (gas exchange), since heat production is proportional to oxygen used (about 5 kcal per litre of $\ce{O2}$).

Define the Respiratory Quotient (RQ) and give its formula.

RQ is the ratio of carbon dioxide produced to oxygen consumed, indicating the fuel being used: $$RQ = \frac{\dot{V}CO_{2}}{\dot{V}O_{2}}$$ RQ of 1.0 indicates carbohydrate use, about 0.70 indicates fat use.

Define the recovery process after exercise.

Recovery is the set of physiological processes that restore the body to its pre-exercise (resting) state, including replenishing energy stores, removing metabolic by-products, and restoring oxygen and fluid balance.

What are the physiological causes (aspects) of fatigue?

Depletion of energy stores (PC and glycogen), accumulation of metabolites (lactic acid, $\ce{H+}$, $P_i$), disturbed ion balance, dehydration, central nervous system fatigue, and reduced neuromuscular transmission.

Differentiate central fatigue from peripheral fatigue.

Central fatigue originates in the central nervous system, reducing neural drive to the muscle; peripheral fatigue occurs within the muscle itself due to factors like substrate depletion and metabolite accumulation.

Define EPOC (Excess Post-exercise Oxygen Consumption) or recovery oxygen.

EPOC is the elevated oxygen consumption above resting level that continues after exercise, used to restore the body, traditionally described as the oxygen debt repaid during recovery.

What are the two components of recovery oxygen (oxygen debt)?

The fast (alactacid) component, which restores ATP-PC stores and reoxygenates myoglobin and blood; and the slow (lactacid) component, which removes/converts accumulated lactic acid.

How are energy stores restored during recovery?

Phosphocreatine is rapidly resynthesized (within a few minutes using aerobic energy), muscle and liver glycogen are replenished over hours through carbohydrate intake, and myoglobin/blood oxygen stores are restored quickly.

What is the fate of lactic acid during recovery?

Lactic acid is mostly oxidized to $\ce{CO2}$ and water for energy, converted back to glucose/glycogen in the liver via the Cori cycle (gluconeogenesis), or used by the heart and other tissues as fuel.