1. The document discusses various physiological responses that occur during exercise, including cardiovascular, respiratory, and endocrine responses. 2. It describes how oxygen consumption increases during exercise to meet energy demands, but an oxygen deficit occurs initially until maximum oxygen consumption is reached. 3. The increased oxygen demands of exercise are met through both aerobic and anaerobic pathways, resulting in increased lactate production and an oxygen debt that must be repaid after exercise through additional oxygen consumption.

2.  Effects of acute & chronic exercises
 Oxygen/CO2 transport - O2 debt
 Effects of Exercises on muscle strength, power, endurance,
 B.M.R.
 R.Q.
 Hormonal & metabolic effects respiratory & cardiac
conditioning
 Ageing
 Training, fatigue & recovery,
 Fitness-related to age, gender,& body type

3. Role of exercise
• In prevention of cardiovascular diseases
• For Physical fitness
• (stress tests) in evaluation of the cardiovascular and
respiratory systems.
• In rehabilitation of the cardiac invalids.

4. Source of energy and metabolic phenomenon during muscle contraction
Chemical composition of muscle
1. Water. major bulk of (75%) the muscle weight.
2. Muscle proteins - 20% of the muscle mass.
• contractile proteins (actin, myosin, troponin and tropomyosin), myogen
and myoglobin..
3. Organic substances other than proteins
• Carbohydrates: glycogen and hexaphosphate.
• Lipids: neutral fat, cholesterol, lecithin and steroids.
• Nitrogenous substances: ATP, adenylic acid, creatine, phosphocreatine,
urea, uric acid, xanthine and hypoxanthine.
4. Inorganic substances –
• Cations: potassium, sodium, calcium, magnesium and
• Anions: chloride, phosphate and sulphate.

5. Energy source for muscle contraction
• The muscle has been labelled as a machine for converting chemical
energy into mechanical work.
• Immediate source - ATP
• Ultimate source - intermediary metabolism of carbohydrate and lipids.
• During muscular contraction, the supply of energy is from the breakdown
of ATP..
ATP → ADP + Pi
↓
Energy
• In about 3 sec, all the ATP stored in the muscle cell is depleted.

6. Resynthesis of ATP
• There are 3 ways in which a muscle fiber can resynthesize ATP from ADP
1. Phosphorylation of ADP by creatine phosphate.
2. Glycolysis.
3. Oxidative metabolism.

7. 1. Phosphorylation of ADP by creatine phosphate.
• Immediately after the depletion of ATP stores of the muscle, ATP is
regenerated using the energy released by the dephosphorylation of
creatine phosphate (CP) reserves of the muscle fibre.
ADP + CP → ATP + Creatine
• Energy produced in this reaction is sufficient to maintain muscular
contraction only for few seconds.

8. 2. Glycolysis
• The next important source of
energy which is used to
reconstitute both ATP and
phosphocreatine, is glycogen
• Previously stored in the muscle
cell by the process of glycolysis
which can sustain muscle
contraction for about 1 min.

9. 3. Oxidative metabolism.
• Oxidative metabolism, i.e. combining of oxygen with various cellular
foodstuffs to liberate ATP is the final source of energy during muscle
contraction.
• This source contributes more than 95% of all energy used by the muscles for
sustained long-term contraction.
• Fatty acids are used for resynthesis of most of the ATP during prolonged
muscle contraction lasting over a period of many hours.
• Glycogen contributes about half of the energy required for muscle
contraction lasting for 2–4 h.

10. Exercise: Types and grading
• Exercise may be dynamic or isotonic and static or isometric.
Dynamic exercise
• Involves isotonic muscle contractions.
• It keeps the joints and muscles moving.
• Examples are swimming, bicycling, walking, etc.
• Dynamic exercise involves external work, which is the
shortening of muscle fibers against load.

11. • In this type of exercise, the heart rate, force of contraction,
cardiac output and systolic blood pressure ↑sed.
• However, the diastolic blood pressure is unaltered or
decreased.
• It is because, during dynamic exercise, peripheral resistance is
unaltered or ↓sed depending upon the severity of exercise.

12. STATIC EXERCISE
• Isometric muscular contraction without movement of joints.
• Example is pushing heavy object.
• Static exercise does not involve external work.
• Increase in heart rate, force of contraction, cardiac output and
systolic blood pressure, the diastolic blood pressure also increases.
• It is because of increase in peripheral resistance during static
exercise.

13. AEROBIC AND ANAEROBIC EXERCISES
• Based on the type of metabolism involved, two types:
1. Aerobic exercise
2. Anaerobic exercise.
• It refer to the energy producing process during exercise.
• Aerobic means ‘with air’ or ‘with oxygen’. Anaerobic means
‘without air’ or ‘without oxygen’

14. AEROBIC EXERCISE
• It involves activities with lower intensity  performed for longer
period.
• Energy - by utilizing nutrients in the presence of oxygen.
• At the beginning-- energy  burning glycogen stored in liver.
• After about 20 minutes -- when stored glycogen is exhausted the
body starts burning fat.

15. • Body fat convert  Glucose - utilized for energy.
• Requires - large amount of O2 to obtain the energy needed for
prolonged exercise.
• Examples :
 Fast walking, Jogging ,Running, Bicycling, Skiing, Skating,
Hockey, Soccer, Tennis, Badminton, Swimming.

16. ANAEROBIC EXERCISE
• It involves exertion for short periods followed by periods of
rest.
• It uses the muscles at high intensity and a high rate of work
for a short period.
• muscles works without oxygen
• Burning glycogen without oxygen liberates lactic acid.
• Accumulation of lactic acid leads to fatigue.

17. • Therefore, this type of exercise cannot be performed for longer
period.
• And a recovery period is essential before going for another burst
of anaerobic exercise.
• Anaerobic exercise helps to increase the muscle strength.
• Examples - Pull-ups, Push-ups ,Weightlifting ,Sprinting ,Any other
rapid burst of strenuous exercise.

18. METABOLISM IN AEROBIC AND ANAEROBIC EXERCISES
•When a person starts doing some exercise For quick
energy first few minutes The muscles burn glycogen
stored in them (without using oxygen).Fat is not burnt.

19. •This is called anaerobic metabolism.
•Lactic acid is produced during this period.
•Presence of lactic acid causes some sort of burning
sensation in the muscles.

20. • Muscles burn all the muscle glycogen within 3 to 5 minutes.
• If exercise continues - glycogen stored in liver is converted into
glucose and transported to muscles.
• Now the body moves into aerobic metabolism as glucose obtained
from liver is burnt in the presence of oxygen.

21. • No more lactic acid is produced.
• So the burning sensation - disappears.

22. • Utilization of all the glycogen stored in liver is completed by
about 20 minutes.
• If the exercise is continued beyond this, the body starts utilizing
the fat.
• The stored fat called body fat is converted into carbohydrate,
which is utilized by the muscles.
• This allows the person to do the exercise for a longer period.

23. Grading of exercise
• There are 4 grades of exercise depending upon the heart rate and oxygen
consumption.
• Oxygen consumption - litres per minute or as relative load index (RLI), i.e.
percentage of maximum O2 utilization.
• The oxygen utilization can also be expressed as MET (metabolic energy
expenditure) test.
• One MET is equivalent to resting O2 uptake of 250 ml/min for an average
adult man and 200 ml/min for an average woman.

25. 1. MILD EXERCISE
• Very simple form of exercise like slow walking. Little or no change occurs in
during mild exercise.
2. MODERATE EXERCISE
• Does not involve strenuous muscular activity. So, this type of exercise can be
performed for a longer period.
• Exhaustion does not occur at the end of moderate exercise. Examples fast
walking and slow running.

26. 3. SEVERE EXERCISE
• It involves strenuous muscular activity.
• The severity can be maintained only for short duration.
• Example - Fast running for a distance of 100 or 400 meters.
• Complete exhaustion occurs at the end of severe exercise.

27. Respiratory Quotient (RQ)
 It is defined as the ratio of carbon dioxide exhaled to oxygen uptake,
reflects substrate utilization when energy is expended.
 Fat and alcohol have RQ values of about 0.7
 compared to 1.0 for carbohydrate, and
 about 0.8 for protein.

28. BMR Definition:
 Your Basal Metabolic Rate (BMR) is the number of calories you burn
as your body performs basic (basal) life-sustaining function.
 Commonly also termed as Resting Metabolic Rate (RMR), which is
the calories burned if you stayed in bed all day.
 In either case, many utilize the basal metabolic rate formula to
calculate their body’s metabolism rate.
 Your BMR defines your basal metabolism rate which makes up
about 60-70% of the calories we use (“burn” or expend).

29. This includes the energy your body uses to maintain the basic function of
your living and breathing body, including:
• The beating of our heart
• Cell production
• Respiration
• The maintenance of body temperature
• Circulation
• Nutrient processing
• BMR, is influenced by a number of factors including age, weight, height,
gender, environmental temperature, dieting, and exercise habits.

30. Muscle mechanics
Common terms used in muscle mechanics
1. Strength of the muscle.
• It is the maximal contractile force produced per cm2 of the cross-sectional
area of the skeletal muscle.
• Normal force - about 3–4 kg/cm2 area of the muscle.
Thus, strength of a muscle ∝ size of the muscle.
• The size of the muscle can be ↑sed by regular exercise.

31. The strength of the muscle is of two types:
1. Contractile strength
• Is exhibited during actual shortening (isotonic contraction) of the muscle.
• For example, the strength developed in the leg muscles during taking off the
body from the ground while jumping is the contractile strength.
2. Holding strength
• It is the force produced while stretching the contracted muscles.
• Example the force developed in the leg muscles while landing after jumping
is the holding force.

32. Power of the muscle.
• Power of the muscle refers to the amount of work done by the
muscle in a given unit of time {kilogram meter per minute
(kgm/min)}
• Thus, the muscle power is the product of strength and speed.
• The power output of a muscle is determined by the energy input
per second and its mechanical efficiency.

33. Endurance of the muscle.
• Endurance of the muscle refers to its capacity to withstand the
power produced during activity.
• In other words, it is the ability of the muscle to contract
repeatedly over time.
• The muscle endurance depends mostly on the nutrition to the
muscle.

34. Muscle tension and excursion
• When a muscle contracts, the external work done is observable as the force
generated by the muscle, which is known as muscle tension, and/or a change
in the muscle length, which is known as muscle excursion.
• Muscle length usually shortens during isotonic contraction.
• However, due to simultaneous passive stretching the muscle length may
increase under certain circumstances.
• In such situations the work done is negative.

35. Muscle action.
• When a muscle or group of muscle contracts, a movement is
produced in the associated part of the skeletal lever system of the
body; such a resultant movement is referred to as the action of
that muscle.
• For example, flexion or extension produced at some joint in the
body is the action of the concerned muscles.

36. Certain facts about muscle mechanics
Certain facts about the muscle mechanics in human body are:
1. Skeletal lever system.
• The muscle, bones and joints form a system of lever.
• According to principles of physics, much greater force is
required to lift the same load, although the speed of lifting is
faster.

37. 2. Advantage of resting length.
• Attachments of most of the muscles in the body are such that
many of them are normally at or near their resting length
when they start to contract, and thus force of contraction
produced is more.

38. 3. Situations for isometric contractions
• In muscles that extend over more than one joint, movement at
one joint may compensate for movement at another in such a
way that relatively little shortening of the muscle occurs during
contraction.
• Such situations (isometric contraction) permit development of
maximal tension per contraction.

39. • Isometric Contractions
• Example - in the case of hamstrings muscles which extend
over the hip as well as knee joint, the lengthening of the
muscles across the hip joint compensates the shortening
across the knee joint.

40. TO BE
CONTINUE………

42. Responses To
Exercise

43. Responses To Exercise
•Exercise - period of enhanced energy expenditure.
•The consumption, which is reflected as greater O2
consumption and CO2 production.

44. • The increased O2 delivery to the tissues and removal of CO2 from
the tissues is achieved by:
Cardiovascular responses to exercise,
Respiratory responses to exercise and
Changes at tissue levels during exercise.
• In addition, endocrine responses to exercise occur and also play a
important role.

45. Oxygen consumption during exercise
• Oxygen utilization is the volume of oxygen which has been actually
consumed during the exercise.
• The maximum amount of oxygen that can be consumed by a person while
performing severe exercise (irrespective of the demand) is VO2 max
(Maximal oxygen consumption).
• It is the level of oxygen consumption beyond which no further increase in
O2 consumption occurs with further increase in the severity of exercise.

46. • VO2 max is probably the
best physiological indicator
of a person’s capacity to
continue severe work, i.e. it
determines the maximum
aerobic work capacity.

47.  Average VO2 max in an adult is 3 L/min and in a trained
athlete it may be as high as 5 L/min.
 VO2 max of a normal individual is limited by the degree to
which cardiac output can increase and not by the
ventilatory capacity or oxygen diffusion capacity of the
lungs.

48. The period of muscular
exercise can be divided into 3
phases.
1. Adaptation phase
2. Steady phase
3. Recovery phase
Oxygen deficit and oxygen debt
Oxygen deficit and O2 debt

49. Oxygen deficit and O2 debt
Oxygen deficit and oxygen debt
1. Adaptation phase
• Beginning (first 2–4 min) 
oxygen consumption ↑ses
linearly and reaches the
maximal O2 consumption (VO2
max).

50. Oxygen deficit and O2 debt
Oxygen deficit and oxygen debt
1. Adaptation phase
• VO2 max < oxygen demand; thus
an oxygen deficit is established at
the beginning of exercise which
continues throughout the period
of exercise.
• Energy requirement - is met with
by the anaerobic pathway.

51. Oxygen deficit and oxygen debt
2. Steady phase
• Characterized by a maximum O2
consumption (VO2 max) throughout,
i.e. a plateau phase .
• The excess energy requirement is
met with by the anaerobic pathway,
i.e. by breakdown of Creatine
Phosphate and Muscle Glycogen.

52. Oxygen deficit and oxygen debt
2. Steady phase
• So blood lactic acid levels
rises.
• In the blood, lactic acid is
buffered by the bicarbonate
buffer as:
H⁺ + HCO⁻ → H2CO3 → CO2 + H2O

53. Oxygen deficit and oxygen debt
• The extra CO2 so evolved is
removed by hyperventilation.
• Trained athletes have greater
tolerance for lactoacidosis than
untrained individuals.
H⁺ + HCO⁻ → H2CO3 → CO2 + H2O

54. Oxygen deficit and oxygen debt
• Further, trained athletes
produce smaller amounts of
lactic acid for a given amount of
submaximal work than an
untrained individual
H⁺ + HCO⁻ → H2CO3 → CO2 + H2O

55. Oxygen deficit and oxygen debt
3. Recovery phase
• Refers to the period after
cessation of exercise during
which extra amount of O2 is
consumed.

56. Oxygen deficit and
oxygen debt
 The amount of extra O2 consumed
during recovery recovery phase is
called O2 debt and is proportionate to
the extent to which oxygen deficit
occurred .
 Or --O2 deficit which occurs during
exercise is repaid in the form of O2
debt.

57. Oxygen deficit and oxygen debt
Extra amount of O2 consumed during is used:
 To remove the excess lactate collected due
to anaerobic glucose breakdown,
 To replenish the ATP and phosphoryl
creatine store,
 To replace the small amounts of O2 that
have come from the myoglobin and
 To resupply dissolved O2 in the tissue fluids
and blood.

58. RESPIRATORY CHANGES DURING EXERCISE
Increased oxygen uptake
• During exercise due to Increased pulmonary blood flow.
• Increased uptake by alveolar capillary blood.
• Increased diffusion capacity due to opening of pulmonary capillaries.
Increased rate and depth of respiration –
• In mild to moderate exercise: Depth is increased.
• In severe exercise: Rate and depth both are increased.
• Initially, only rate is increased and later on both are increased. Rate may vary
up to 40/min.

59. EFFECTS ON LUNGS
• During exercise there is increase in CO2 of blood
• Chemoreceptor in medulla are stimulated
• Stimulation of dorsal respiratory group ofneurons
• Increase the rate of respiration
• Removal of CO2 is increased

60. CARDIOVASCULAR RESPONSES TO EXERCISE
 Increase in the skeletal muscle blood flow
 Redistribution of blood flow in the body
 Increase in the cardiac output,
 Blood pressure changes and
 Changes in the blood volume.

61. EFFECTS OF EXERCISE ON CARDIOVASCULAR SYSTEM
1. ON BLOOD
• Mild hypoxia developed during exercise  juxtaglomerular apparatus 
erythropoietin  bone marrow  red blood cells.
2. ON BLOOD VOLUME
• More heat during exercise  stimulate  thermoregulatory system.
• This in turn, causes secretion of large amount of sweat leading to:
I. Fluid loss
II. Reduced blood volume
III. Hemoconcentration
IV. Sometimes, severe exercise leads to even dehydration.

62. 3. ON HEART RATE
• HR ↑ses during exercise.
• b/c - impulses from cerebral cortex  medullary centers, which reduces
vagal tone.
• ↑sed HR – b/c of vagal withdrawal. ↑se in sympathetic tone also plays
some role.
Moderate exercise – HR ↑se to 180 beats/minute.
Severe muscular exercise- HR ↑se -240 to 260 beats/minute.

63. Increased heart rate during exercise is due to four factors:
I. Impulses from proprioceptors[in the exercising muscles]  higher centers
 ↑sed HR
II. ↑sed CO₂ tension medullary centres ↑sed HR
III. ↑sed body temperature  cardiac centers via hypothalamus, also
stimulates SA node directly  ↑sed HR
IV. Circulating catecholamine's  ↑sed HR

64. 4. ON CARDIAC OUTPUT
• CO ↑sed up to 20 L/minute [moderate exercise] 35
L/minute [severe exercise].
↑se CO is ∝ ↑se in the amount of oxygen consumed.
• ↑se CO because of ↑sed HR and ↑sed SV.
• ↑sed HR because of vagal withdrawal.
• ↑sed SV due to ↑se force of contraction.

65. 5. ON VENOUS RETURN
• Venous return ↑ses remarkably during exercise because of
muscle pump, respiratory pump and splanchnic
vasoconstriction.

66. BLOOD PRESSURE CHANGES DURING EXERCISE
In systemic circulation
• ↑se SBP  ↑se CO.
• DBP  depends upon the peripheral resistance  mildly ↑se / ↓se remain
unchanged depending upon the change in total peripheral resistance.
• Mostly, the vasodilatation in the skeletal muscles balances the
vasoconstriction in other tissues
• So DBP is usually not changed much.
• MABP  is usually ↑sed

67. 6. ON BLOOD FLOW TO SKELETAL MUSCLES
• During exercise ↑se amount of blood flow  skeletal muscles.
• Rest  blood flow - 3 to 4 mL/100 g of the muscle/minute.
• ↑ses up to 60 to 80 mL in and up to 90 to 120 mL in severe exercise.
• During the muscular activity  the muscles contract  compression of
blood vessels . Between the contractions, the blood flow ↑ses .
• Sympathetic nerves cause vasodilatation in muscles.

69. • LINKING TOGETHER
• The heart and lungs are connected
to supply the body with oxygen rich
blood and work together to take
away and get of carbon dioxide rid.
• This happens at the capillary
networks that cover the alveoli and
muscle cells.

70. AT TISSUE LEVEL
• Blood flow is increased due to dilation of blood capillaries. So, mean
distance between the blood and tissues is decreased.
• Increased pO2 gradient between capillaries and surrounding tissues.

71. OTHER CHANGES DURING EXERCISE
• ADH increases to increase water reabsorption from kidney.
• Catecholamines are increased to provide fuel to exercising muscle by
mobilising free fatty acids and increasing blood glucose.
• ACTH and cortisol increase to reduce exercise stress and to mobilise fats to
be used as source of energy.
• Glucagon increases and promotes glycogenolysis.
• Insulin reduces, leading to improved glucose control in diabetes.
• Endorphins increase and provide a feeling of well-being after exercise.
• Aldosterone is increased which reduces urinary loss of water and sodium.
So, maintains fluid balance in presence of excessive sweating.

72. BENEFITS OF REGULAR EXERCISE ONTHE BODY (TRAINING)
Exercise under Hot and Cold Environments-Adaptive
A. Body responses to exercise in the hot environment.
1. Sweat secretion increases called thermal sweating.
I. This decreases skin temperature
II. Prevent rise in core temperature.
III. Less demand for blood flow to the skin
2. Production of ADH and aldosterone increases
I. This increases plasma volume.
II. Prevent excess loss of sodium, chloride and water by the skin and
kidney

73. 3. Body core temperature is kept low as heat dissipating mechanisms
are more efficient.
4. Heart rate is low at any given work load (as the core temperature is
kept low).
5. Person continues to work for long period and onset of fatigue is
delayed. (As muscle glycogen is not depleted).

74. B. Adaptive body responses to exercise in the cold environment
1. Exercise in the cold can affect muscle function. Muscular contraction is
less efficient.
2. Cooling changes the recruitment pattern of nervous system and muscle
fibres.
3. Muscle glycogen utilization is higher during exercise in cold environment.
4. Cutaneous vasoconstriction reduces heat loss to the environment and
prevent a fall in core temperature.

75. 5. Catecholamines, thyroid hormone secretion increases.
6. They increase heat production with less ATP formation SNS becomes
more active.
7. Muscle fatigue is delayed.
8. Brown fat may participate in the production of heat. Thus, preventing fall
in core temperature. Failure of adaptation to cold environment leads to
hypothermia.