Effects of exercise on the respiratory system.

Dr Abdulrahman AlhowikanCollage of medicine

Physiology Dep.

Aims

By the end of this lecture the students should be able to:

Understand the difference between dynamic and isometric exercise.

Describe the effects of moderate and severe exercise on oxygen consumption (Vo2 Max) , and ventilation volumes.

Describe the effects of exercise on arterial PO2, PCO2 and H+ ions.

Define the diffusing capacity of the respiratory membrane, and its typical values at rest, and explain its changes in exercise.

Explain causes of hyperventilation in exercise.

the difference between dynamic and isometric exercise

isometric exercise Muscle contraction is said to be isometric (static)

when the muscle does not shorten during not shorten during contraction static strength training, involve muscular actions in

which the length of the muscle does not change length of the muscle does not change and there is no visible movement at the joint eg Pushing wall

strengthening the muscles without stress strengthening the muscles without stress on the joint eg in rehabilitation

 drives up blood pressure and Valsalva-ManeuverValsalva-Maneuver static strength required to stabilize the upper and

lower body

the difference between dynamic and isometric exercise cont…

dynamic exercise dynamic exercises increase strength

throughout the full rang of motionfull rang of motion Blood circulation, strength, and endurance endurance

are improvedare improved by these continuous movements

Eg. swimming, walking

effects of moderate and severe exercise on oxygen consumption, and ventilation

volumes.

Normal oxygen consumption (Vo2 Max)

for a young man at rest is about 250 250 ml/min.ml/min.

However, under maximal conditions! Untrained average male 3600ml/min Athletically trained average male 4000ml/min Male marathon runner 5100ml/min

(40-50) y (30-39) y (20-29) y Reference

36.1

40.4 46.3 German medical staff

42.3 47.4 51.7 Canadian Sedentary

23.9 28.88 31.55 Saudi sedentary

Compare Maximal oxygen consumption with other population

Peak cardiopulmonary function in healthy Saudi males (mean ± SD). (103)

Age (years) Variables

(40-50) (30-39) (20-29)

1.93± 0.27 2.23 ± 0.29

2.22 ±0.32 VO2 peak (L. min-1)

23.9± 3.6 28.9± 5.5 31.6±5.9 VO2 peak (ml. kg.-1 min-1)

172 ± 8 178±8 183 ± 8 HR peak (bpm)

82.3 ± 14.2

90.2±15 89.6±14.6 VE peak (L. min-1)

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effects of exercise intensity on oxygen consumption

during the first 60-120 seconds of effort there is an increase in pulmonary blood pulmonary blood

flowflow (phase I or the cardio‑dynamic cardio‑dynamic phasephase)

before a rapid increase in oxygen consumption related to muscle extraction muscle extraction of O2of O2 (phase II or the oxygen uptake kinetic phasekinetic phase)

before reaching steady-statebefore reaching steady-state (phase III) if the work load does not result in the accumulation of blood lactate.

Relation between oxygen consumption and total pulmonary ventilation at different levels of exercise.

There is a linear relation between both oxygen consumption oxygen consumption (Vo2 Max) and total pulmonary ventilation pulmonary ventilation increase about 20-fold between the resting state and maximal intensity of exercise in the well-trained athlete.

Causes of hyperventilation in exercise.

During maximal effort: Pulmonary ventilation at maximal exercise

100-110L/min Maximal breathing capacity Maximal breathing capacity 150-170L/min maximal breathing capacity is about 50 %

greater than the actual pulmonary ventilation during maximal exercise. to giving athletes extra ventilation E.g

(1) exercise at high altitudes, (2) exercise under very hot conditions, and (3) abnormalities in the respiratory system.

Causes of hyperventilation in exercise cont...

Respiration is stimulated mainly by neurogenic mechanisms neurogenic mechanisms during exercise

 Stimulation results from direct stimulation of the respiratory center by the same nervous signals that are same nervous signals that are transmitted from the brain transmitted from the brain to the muscles

An additional part is believed to result from sensory signals transmitted into the sensory signals transmitted into the respiratory centerrespiratory center from the contracting muscles and moving joints

Effects of exercise on arterial PO2, PCO2 and H+ ions.

Many studies have since reported that the lactat threshold (LT) is strongly correlated with ventilatory (LT) is strongly correlated with ventilatory anaerobic threshold (VAT)The term VAT actually refers to the onset of exercise induced hyperventilation during effort. This increase in is a This increase in is a homeostatic response to deal with the consequences homeostatic response to deal with the consequences of the excess lactate production of the excess lactate production which can dissociate to release H+ to release H+ ions from lactic acid into the blood stream. The H+ ions are buffered by bicarbonate and The H+ ions are buffered by bicarbonate and release CO2 release CO2 .This buffering of lactic acid results in extra CO2 extra CO2 production over that produced by aerobic metabolism and increases the arterial CO2 partial pressure (PaCO2). The increase in PaCO2 stimulates excess ventilation that follows on from the lactate threshold.

the lactat threshold (LT) is strongly correlated with ventilatory

http://www.youtube.com/watch?v=VBJ97oeyor0

Oxygen-Diffusing Capacity of Athletes

The oxygen-diffusing capacity is a measure of the rate at which oxygen can diffuse from the rate at which oxygen can diffuse from the pulmonary alveoli into the bloodthe pulmonary alveoli into the blood

It is expressed in terms of milliliters of oxygen that will diffuse each minute for each millimeter of mercury difference between alveolar partial pressure of oxygen and pulmonary blood oxygen pressure.

Oxygen-Diffusing Capacity of Athletes cont…

 differences between diffusing differences between diffusing capacity at resting and the state of capacity at resting and the state of maximal exercise maximal exercise make blood flow through many of the pulmonary capillaries and providing greater  providing greater surface area through which oxygen surface area through which oxygen can diffuse into the pulmonary can diffuse into the pulmonary capillary of blood.

Oxygen-Diffusing Capacity of Athletes cont…

The saturation of red blood cells in the pulmonary capillary influenced by cardiac outputcardiac output. And that, might reducing the time for saturation of red blood cells with oxygen In addition, the saturation of blood artery (%SaO2) remain constant 95% at rest and during remain constant 95% at rest and during maximal effortmaximal effort, due to proportional correlation between diffusion of red blood cells and increase exercise intensities.

However, the impact of reduce pulmonary diffusion in pulmonary diffusion in oxygen uptake can be noticed in the reduction of oxygen uptake can be noticed in the reduction of exercise capacity by exercising at high altitudes exercise capacity by exercising at high altitudes level (3000-5000 m) in which the O2 concentration at atmosphere reduced less than 20.9% in addition, that can be noticed in patients with COPD such patients with COPD such as exercise induce by asthma.

Thank you

Reference book

Guyton & Hall: Textbook of Medical Physiology 12E