IMPACT OF AGING PROCESS ON GENERAL HEALTH

AGE DIFFERENCES Differences in endurance and physical work capacity

among children, young adults, and middle –aged or elderly individuals are evident.

some comparisons are made between maximum oxygen uptake and the factors influencing it and among the blood pressure , respiration, vital capacity, and maximum voluntary ventilation in the different age categories.

It is important when developing aerobic conditioning programs that these age-related differences are taken into consideration.

Effect of aging on the some physiological parameter

1) Heart rate 2) Stroke volume3) Cardiac output 4) Maximum oxygen uptake5) Blood pressure6) Respiration7) Muscle mass and strength

Heart Rate Def:- it is number of beats/min.

Resting heart rate:- It is a person's heart rate when they are at rest: awake but lying down.

Maximum heart rate:-It is the highest pulse rate you can attain during all-out effort. Maximum heart rate is estimated with the formula 220-age. But this is only an estimation, and not particularly accurate.

After birth as age vagal tone & heart rate , but in old age heart rate is slightly higher due to fall in vagal tone.

Vagal tone in old age due to degenerative changes taking place in the nerve fibers.(Vagal tone is parasympathetic supply through the vagus nerve & parasympathetic nervous stimulation causes reduction in heart rate.)

Physiological parameters

YOUNG ADULTS OLDER ADULTS

1) HEART RATE(no. of beats /min.)

Resting heart rate reaches 60 to 65 beats per minute at 17 to 18yrs of age(75 beats per minute in a sitting , sedentary young man)

[In sedentary young man HR is more than normal because•In sitting position the gravity acts more on heart than in supine so more powerful contraction is required to meet the body requirement.•It may also be due to obesity which leads to fat deposition in the arteries & hence resistance to blood flow through the blood vessels, to overcome this resistance the heart has to pump with much greater speed.]

Resting heart rate is not influenced by age.

Maximum heart rate is aged –related and decreases with age (in very general terms, 220 minus-age) The average maximum heart rate for men 20 to 29yrs of age is 190 beats/min. for men 60 to 69yrs of age, it is 164beats /min.[due to old age muscle walls of heart becomes weak it’s recoiling ability which leads to myocardial contractility & results in reduction of heart rate.]

The amount that the heart rate increases in response to static and maximum dynamic exercise (hand grip) decreases in the elderly.

Maximum heart rate is age-related (190 beats per minute in the same sedentary young man)

[max. heart rate is generally measured during exercise. During exercise there is demand of oxygen and blood nutrient by the body which leads to stimulation of sympathetic nervous system which causes increase in myocardial contractility & results in heart rate.]

Stroke volume Def:- The amount of blood pumped

by the ventricles of the heart in one beat.

Stroke volume increases during exercise due to:-

1.Increase in myocardial contractility by epinephrine and non-epinephrine.

2.Increase heart rate.

2) STROKE VOLUME(The amount of blood pumped by the ventricles of the heart in one beat.)

The adult values for stroke volume are 60 to 80ml(75ml in a sitting ,sedentary young man)

With maximum exercise ,stroke volume is 100ml in that same sedentary young man.

Stroke volume decreases in the aged and results in decreased cardiac output.[ elasticity of blood vessels due to old age or due to arteriosclerosis leads reduce venous return which causes in stroke volume.Due to elastic recoiling ability of heart there is myocardial contractility which cause decrease in heart rate which results in stroke volume.]

Cardiac output Def:- It is volume of blood pumped from a

ventricle of the heart/min. It is the product of heart rate and stroke volume.

Cardiac output is increased during exercise due to increase in HR and stroke volume.

Higher values of cardiac output can be achieved in young's as compared to old subjects due to higher max. heart rate in young's.

3) Cardiac output(volume of blood pumped from a ventricle of the heart/min. It is the product of heart rate and stroke volume)

Cardiac output at rest is 75beats/min × 75ml,or 5.6liters/min.

With maximum exercise , cardiac output is 190beats/min ×100ml, or 19liters /min )

Cardiac output decreases on an average of 7 to 3.4litres /min. from 19 to 86yrs

Maximum Oxygen Uptake.

Def:-It is a measure of the body’s capacity to use oxygen or the maximum amount of oxygen consumed by the body/min. when an individual reaches maximum effort.

VO2 max. of an individual determines the maximum aerobic work capacity i.e. it is the best physiological indicator of aerobic work capacity of man.

During exercise it increases due to O2 delivery to the tissue due to:-

• in cardiac output.• in alveolar ventilation.• in capillary density.

It depends on muscle mass and functional dimensions of O2 transporting system.[stroke volume, HR, a-vO2 difference.]

It is usually measured when performing an exercise that uses only large muscle groups such as swimming, walking and running.

It is influenced by age, gender, heredity, inactivity and disease.

It is expressed relative to body weight as ml of oxygen per kilogram of body weight per min.

It is dependent on oxygen binding capacity of blood, cardiac function, oxygen extraction capabilities.

4) Maximum oxygen uptake (it is a measure of the body’s capacity to use oxygen or the maximum amount of oxygen consumed by the body per min.)

The difference in VO2max between males and females is greater in adult.

Resting VO2 max. is

250ml/min.

Differences in VO2max between the sexes is minimum

when VO2max is

expressed relative to lean body weight.

In sedentary young man, maximum oxygen uptake equals 3000ml/min. (oxygen uptake at rest is equals 300ml/min.)

According to cardio –respiratory fitness classification, if men 60 to 69yrs of age of average fitness level are compared with men 20 to 29yrs of age of the same fitness level, the maximum oxygen uptake for the older man is lower 20 to 29 yrs : 31 to 37 ml/kg/min.60 to 69yrs : 18 to 23ml/kg/min. Aerobic capacity decreases about 10% per decade when evaluating sedentary men. Maximum oxygen consumption decreases on an average from 47.7 ml/kg per min. at age 75yrs. This decrease is not directly the result of age; athletes who continues exercising have significantly less decrease in VO2max when evaluated over 10_yrs period.

Blood pressure It is defined as lateral pressure exerted

by column of the blood on vessel wall.

Systolic pressure:-It is defined as max. pressure in arteries during systole of the heart.

Diastolic pressure:-It is defined as minimum pressure in arteries during diastole of the heart.

5) Blood pressure

Systolic blood pressure is 120mm Hg(avg.). At peak effort during exercise, values may range from as low as 190mm Hg to as high as 240mm Hg.

Diastolic blood pressure is 80 mm Hg (avg.). Diastolic pressure does not changes markedly with exercise.

Blood pressure increases because of increased peripheral vascular resistance.

Systolic blood pressure of aged is 150mm Hg(avg.) Diastolic blood pressure is 90mm Hg(avg.)

Systolic blood pressure Increases in linearity with severity of exercise at all ages

and may increase to 200mmHg.

It is mainly due to sympathetic stimulation of heart during exercise.

Increase is more in older subjects, because resting SBP is more due to arthrosclerosis.

SBP increases more than DBP due to decreased distensibility of arteries as the age increases.

Increase cardiac output.

Vasoconstriction of non working muscles to the working muscles .

Diastolic blood pressure DBP remains normal [except in very severe exercise ]

because it depends on peripheral resistance. During exercise due to sympathetic stimulation there is vasoconstriction but due to local regulatory mechanism in the exercising muscle there is vasodilatation. So peripheral resistance remains normal.

In obese people [brachial arterial pressure gives high readings] because there is more tissue between the “cuff” and the artery.

The pressure in any vessel below heart is increased and that in any above heart is decreased by the effect of gravity.

Emotional stress – during emotional stress there is sympathetic stimulation which causes increases in BP.[BP above 140/90mmHg is termed as hypertension.]

Respiration Respiration is the process by which oxygen is taken in and

carbon dioxide is given out.

Vital capacity(VC):- It is the maximal volume of air which can be expelled from the lungs by forceful effort following maximal inspiration.

VC=TV+IRV+ERV• TV(tidal volume):-It is the volume of air breathed in or out of

lung during quiet breathing.{TV:-500ml}• IRV(inspiratory reserve volume):-It is the maximal volume of

air which can be inspired after completing normal tidal inspiration.{IRV:-2000-3500ml}

• ERV(expiratory reserve volume):-IT is the maximal volume of air which can be expired after a normal tidal expiration. {ERV:-750-1000ml}

Advantages:-It provides useful information of the strength of the respiratory muscle therefore maximum inspiratory & expiratory effort can be assessed.

1) VC in males 2.6liters/m2BSA.female 2.1litera/m2BSA.

Because of large chest size, more muscle power, more body

surface area.

2) Age:- decreases due to loss of elasticity of the lungs.

3) Strength of respiratory muscles in swimmer & diver.

4)VC decreases in pulmonary fibrosis.

Maximum voluntary ventilation:-It is the largest volume of air that can be moved into and out of the lungs in one min. by maximum voluntary effort. {MVV:-100l/min.}

6) Respiration

Respiratory rate is 12 to 15 breaths/min.

Vital capacity is 4800mL in a 20 to 30yrs of age.

Maximum voluntary ventilation varies considerably from laboratory to laboratory and is dependent on age and the surface area of the body.

Respiratory rate increases with age.

Vital capacity decreases with age. There is a 25% decrease in vital capacity of the 50 to 60yrs old man compared with the 20 to 30yrs old man with same surface area.

Maximum voluntary ventilation decreases with age.

7) Muscle mass and Strength

Muscle mass increases with training as a result of hypertrophy. This hypertrophy can be result of an increased number of myofibrils, increased actin and myosin, sarcoplasm, and/or connective tissue.

Limited evidence suggests that number of muscle fibers may increase, referred to as hyperplasia.

As the nervous system matures, increased recruitment of motor units or decreased autogenic inhibition by Golgi tendon organ appears also to dictate strength gains.

Generally, the strength decline with age is associated with a decrease in muscle mass and physical activity.

The decrease in muscle mass is primarily due to a decrease in protein synthesis, in concert with a decline in the number of fast-twitch muscle fibers.

Aging may also affect the strength by slowing the nervous system’s response time. This may alter the ability to recruit motor units effectively. Continued training as one ages appears to reduce the effect of aging the muscular system.