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( O L D E R P O P U L A T I O N )

Aerobic Training

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Physiological Responses

Physiological Adaptations

Aerobic Training

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1) CARDIOVASCULAR

2) RESPIRATORY

3) METABOLIC

Physiological Responses

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Cardiovascular Responses

Heart rate maximum(HRmax) ----> Decreases.

Eg. HRmax of children=200 beats/min

HRmax of 60 years= 160 beats/min Every year HRmax DECREASES by less than 1

beat/min.

WHY?

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Reasons:

1) Electrophysiological & Morphological changes inCardiac Conducting System.

Slowing down of Cardiac Conduction

Decrease in hearts Intrinsic Rate

Decrease in sensitivity of heart to CatecholamineStimulation

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Cont..

2) Maximal stroke Volume (SVmax) = Decreases ( withage)

3) Maximal Cardiac Output (Qmax) = Decreases

BUT, Heart Volumes in older athletes are similar tothose of younger athletes.

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Cont..

Leg Blood Flow DECREASES at 50 years of age,

because the Peripheral Resistance INCREASES as aperson ages.

A STUDY SAYS:

In older endurance trained athletes, Leg Blood Flow , Vascular Conductance, & Femoral Venous Oxygen

Saturation were each LOWER by 20% - 30% in oldermen at each SUBMAXIMAL LEVEL WORK RATE,however, there is an INCREASED SUBMAXIMAL a-

vO2 difference.

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Respiratory

In old athletes :

Qmax DECREASES ----> So ----> VO2max DECREASES

Vital Capacity (VC) & Forced Expiratory Volume in1sec (FEV1)----> DECREASES linearly with age.

WHEREAS----> Residual Volume (RV) = INCREASES

AND ----> Total Lung Capacity (TLC) = REMAINSUNCHANGED.

HENCE----> RV/TLC = INCREASES(So less air is exchanged)

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Cont..

Maximal Expiratory Ventilation (Vmax) = DECREASES

Vmax----> Increases, during growth until physical maturity

----> Later----> Decreases, as a person ages.

40 L/min(4-6 yearsold boy)

110-140 L/min

(Fully maturedmen)

70-90 L/min

(60-70 yearsold men)

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Cont..

Aerobic Capacity = Decreases (with age).

Pulmonary changes that accompany aging areprimarily caused by a loss of elasticity in the lung

tissue and the chest wall. However, aging athletes have only slightly decreased

pulmonary ventilation capacity. For them, theprimary limiter of VO2max appears to be decreased

oxygen transport to the muscles.

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Metabolic Function

1) VO2max = Decreases (with age)

Reasons:

Decreased VO2max

Decrease in HRmax

1

2

Decrease in SVmax

1

2

Decrease in Maximal

a-vO2 difference

1-->2-->3-->.

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A) Normally Active People:

Changes in VO2max. Among normally ACTIVE MEN:

Age(years) VO2max,(mlkg-1min-1)

% change, from25 years

25 47.7 _

35 43.1 -9.6

45 39.5 -17.2

52 38.4 -19.5

63 34.5 -27.7

75 25.5 -46.5

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Cont..

VO2max DECREASES by about 10% per decadewith aging, starting in the mid-teens for women, and

in the mid-20s for men.

This DECREASE is largely associated with a decrease

in CARDIO-RESPIRATORYfunctions.

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B) Older athletes

VO2max declines with age and the rate of decline isapproximately 1% per year.

Factors that influences this rate of decline are: General activity level

Volume of training

Intensity of training Increased body weight and body fat mass, and

decreased fat free mass

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Graph : Changes in VO2max in trained anduntrained men

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Lactate Threshold

Lactate threshold, expressed as a % of

VO2max, unexpectedly INCREASES with aging.

The significance of this is not understood.

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Physiological Adaptations

VO2max Improvements : (Males+Females) Aged = Less

Young = More

But Absolute VO2 INCREASE of 5.5 - 6.0ml/kg/min similar for both(recent studies).

Young ( 21 25 years) & Aged (60 71 years) = Shows SIMILARimprovements in VO2max with training.

VO2max in aged males and females is also closely similar , after 9-12months of aerobic training. [males= 21% ; females= 19%]

What is the difference, then, in young and aged ?Young: Increase in VO2max is DUE TO increased Cardiac Output(CO).

Aged : Increase in muscles oxidative enzyme activities.

[So, peripheral factors play major role in older subjects than in youngersubjects.]