Respiratory System under stress

AIMS: 1. What physiological changes

occur with exercise in the respiratory cardiovascular and muscular systems?

2. What are the limitations to exercise in health and disease?

3. What are the effects of altitude, O2 toxicity, diving & foetal environments on the lungs?

EXERCISE

Aerobic (dynamic, isotonic) Non-aerobic ( isometric, static)

Isokinetic Short or long term Successful exercise

muscular, CVS, respiratory Adequate gas exchange- O2 & CO2

Availability of fuel- oxidation of glycogen, glucose, fatty acids

STEPS IN EXERCISE

3 STAGES 1. Anticipation- preparatory, HR,

C.O. 2. During- main changes- metabolic,

respiratory,CVS, blood flow redistribution blood flow to muscles 1 to 22-33 l.min-1

SNS, metabolic hyperaemia, indirect PNS

3. Recovery- return to resting conditions, payback of O2 debt, metabolic replenishment

Physiological changes Respiratory

VE, Pulmonary blood flow, bronchial dilation, VO2,VCO2

PaO2 ,PaCO2, anaerobic metab., pH, RQ

O2 extraction- intensity, capillary density, Bohr shift to right, aerobic enzyme activity

CVS SP, DP, C.O. SV, H.R

Muscular muscular contraction

motor cortex action potential Ca2+ release cross-bridges

MetabolicAnaerobic - creatinephosphate (CP),

glycolysis of glucose, lactic acidAerobic- ATP, glycogen (muscle),

carbohydrates and fats, glycogen (liver)

Intensity of exercise - CP, glycogen, pH, K+; lactate, ADP, AMP, Pi

replenishment Fatty acids- from lipolysis, lipases, A,

Glucagon,cortisol Glucose- from glycogenolysis, A, GH,

Glucagon

LIMITATIONS TO EXERCISE RESPIRATORY DISORDERS

Ventilation, gas exchange, exercise capacity; exercise responses variable & difficult to predict from resting values

COPD VE varies, weak skel. Muscle,

aerobic capacity & PaO2, lactate & dead space, high V/Q

RESTRICTIVE high f, stiff lungs, PaO2, low V/Q,

high dead space Symptoms during exercise

sense of effort in breathing, inspiratory muscle strength - dyspnoea

PaO2 & PaCO2 - dyspnoea Cardiovascular disorders-

exercise capacity, Hrmax, SV, muscle weakness & blood flow, lactate

CONCLUSIONS 1.Excercise involves changes in

respiratory (VE, VT, f, VCO2, VO2), cardiovascular (C.O., SV, HR,BP) & muscular ( blood flow, ATP, force generation) systems.

2.Limitations - health- inadequate fuel, delivery of O2,

removal of CO2

disease- perceived effort, weak muscles, poor gas exchange

3. Other environments Altitude- HV leads PaCO2, alkalosis, loss of

bicarbonate, further increase of ventilation & polycythemia.

high O2 - toxic, can damage lungs by impairing gas exchange, oedema, atelectasis.

Diving descent- increase in gas density, compression of gas cavities, N2 dissolves into body tissues. Ascent causes expansion of gas cavities, Bends.

Fetal respiration- placenta, no air, shunting of oxygenated blood from RA to LA & then to aorta, also to RV & then to aorta. Following birth, air enters, lung liquid removed, loss of shunts.

TRAINING Repeated physical exercise (frequency,

type, intensity) training effect ‘Large muscle rhythmic activity for 20-

30 min, 3-5 days/week at 60-80% (55-60% VO2 max) age adjusted maximum heart rate’ for 6-10weeks. - ACSM Isometric

advantages- I lean tissue, strength, flexibility, Psychological benefits

small changes- H.R, cholesterol, chamber size, VO2max

disadvantages- anaerobic energy used, S.P & D.P, blood flow at high workloads

Advantages of exercise strength of bones, ligaments, cartilage &

muscle, fibrinolysis, HDL, lean tissue, weight loss osteoporosis, risk of Diabetes Mellitus, mortality

of post MI patients blood flow, faster recovery from illness,

pulmonary rehabilitation ? Slow ageing, psychological benefits

Disadvantages Injury (tendons, cartilage), osteoarthritis, Ischaemia,

strokes, exercise induced asthma sudden death, weakens immune system, addiction to

exercise,

DETRAINING Prolonged bed rest, inactivity Space ‘Ageing’

decrease heart response, elasticity of blood vessels, increased B.P

stiffness of rib cage, vital capacity, work of breathing

speed and muscle strength, earlier fatigue, bone loss

reaction times, sensory loss, ANS BMR, lean tissue, body fat, glucose

tolerance

Reversal of training effects autonomic response body fat, cholesterol osteoporosis, muscle atrophy joint mobility, metabolism O2 extraction, VO2max heart size, HR, C.O.