age and fitness on the pressor response in elderly

Influence of Age and Fitness on the Blood Pressure Response to Two Modes of Dynamic Exercise

Dustin Grinnell

Physiology Department

Pennsylvania State University

Outline• Scope of the Problem/Significance

– Aging and blood pressure– Aerobic fitness and its influence on blood pressure in the aged – Active muscle mass and the blood pressure response

• Background– The blood pressure response to two modes of graded dynamic exercise

• Introduction– To three main questions we proposed.

• Methods– Proctor lab fitness study

• Results – To three main questions

• Summary– What age, fitness, gender and mode of exercise conclusions can we draw?

Aging and Blood Pressure

• It is well known that age is associated with a rise in resting and exercise blood pressure.

• Hypertension afflicts between 33 and 57% of men and 25 and 60% of women between ages 45 and 74.

• Resting: • 20 mm Hg systolic and 10 mm Hg

diastolic increment increase in blood pressure from age 30 to 65 years.

• Exercise: • Many studies show that there is

a heightened blood pressure response in the aged to graded dynamic exercise.

Fitness and the Blood Pressure Response in the Aged

• We know: age is associated with a higher resting and exercise blood pressure

• Regular aerobic training • Reduces systolic and diastolic blood pressure during rest

and sub-maximal exercise. The largest reduction occurs in systolic blood pressure.

• Exercise training and hypertension • For hypertensive older men and women, 9 months of low-

intensity, aerobic exercise lowered SBP by 20 mm Hg and DBP by 12 mm Hg.

Blood Pressure and the Active Muscle Mass

• Research has shown that the blood pressure response to exercise is determined by the active muscle mass.

• Relationship

• The magnitude of the pressor response is inversely related to the size of the active muscle.

• Therefore the blood pressure response to the use of a large muscle mass has been shown to be less pronounced when compared to small.

• Blood Pressure with Graded Exercise– Systolic blood pressure: after initial rapid rise from resting level increases linearly with

exercise intensity.

– Diastolic blood pressure: remains stable or decreases slightly at higher exercise levels.

– During maximum exercise by healthy, fit men and women, SBP may increase to 200 mm Hg or higher despite significantly reduced total peripheral resistance.

• The Pressor response – The increase in blood pressure response to an exercise stress.

– We are defining it as the rise in blood pressure with increasing workload, or multiples of metabolic rate (MET).

Background

Background

• Graded Exercise Tests– Can be used to evaluate functional capacity

– Usually given on a motorized treadmill or bicycle ergometers.

– Workload intensity (how hard the subject is working) is adjusted by progressively increasing the speed and incline/resistance on the machine.

– The test starts at a low intensity and continues until a prespecified workload is achieved physiologic symptoms occur, or the subject is too fatigued to continue.

BackgroundLarge vs. Small Muscle Dynamic Exercise

VO2max Test

Knee Extension Exercise

Introduction• Purpose:

• To explore the blood pressure responses to two modes of dynamic exercise.

• Question #1 • Does aging affect the pressor response?• How does the response compare between large and

small muscle exercise?

• Question #2• Does fitness affect the pressor response in the aged?• How does it compares across exercises?

• Question #3• Is the pressor response determined by the active muscle

mass?

Methods• Six groups of subjects recruited for “fitness study”:

• Younger men and women (20-30 yr)• Older high and low fit men (60-79 yr)• Older high and low fit women (60-79 yr)• Non-obese, normotensive• n= 5-10 per group

• All subjects performed:• A large muscle exercise, a VO2max treadmill running test.

– Treadmill speed and incline is increased every three minutes until exhaustion.

• A small muscle exercise, a one-legged knee extensor exercise.– Work rate is increased in a graded fashion (every 3 minutes, 5W and 10W

increments for women and men, respectively) until the participant cannot maintain the knee kick cadence (40 kicks per minute).

• Variables recorded:• Pulmonary gas exchange (VO2) using a metabolic cart• Blood pressure via auscultation • Heart rate via ECG

Question #1

Does aging affect the pressor response?

How does the response compare between large and small muscle exercise?

Question #1: ResultsTreadmill Exercise

Men

Age Group

YM OM (LF)

SB

P S

lop

e (

SB

P v

s.

ME

T)

0

2

4

6

8

10

12

14

16

18

SBP

Women

Age Group

YW OW (LF)

SB

P S

lope (

SB

P v

s.

ME

T)

0

2

4

6

8

10

12

14

16

18

SBP

P = 0.03

Systolic Blood Pressure

P = 0.24

Question #1: ResultsTreadmill Exercise

Diastolic Blood Pressure

Men

Age Group

YM OM (LF)

DB

P S

lope (

DB

P v

s.

ME

T)

0.0

0.5

1.0

1.5

2.0

2.5

DBP

Women

Age Group

YW OW (LF)

DB

P S

lope

(D

BP

vs.

ME

T)

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

DBP

Question #1: ResultsKnee Kick Exercise

Men

Age Group

YM OM (LF)

SB

P S

lop

e (

SB

P v

s.

ME

T)

0

5

10

15

20

25

30

35

SBP

Women

Age Group

YW OW (LF)

SB

P S

lop

e (

SB

P v

s.

ME

T)

0

5

10

15

20

25

30

35

SBP

Systolic Blood Pressure

P = 0.02

Question #1: ResultsKnee Kick Exercise

Diastolic Blood PressureMen

Age Group

YM OM (LF)

DB

P S

lope

(D

BP

vs.

ME

T)

0

5

10

15

20

25

DBP

Women

Age Group

YW OW (LF)

DB

P S

lope

(D

BP

vs.

ME

T)

0

5

10

15

20

25

DBP

P = 0.13 P = 0.03

Question #1: Results

• Question #1 – Age Effect?

• During large muscle exercise • SBP - Old men show a heightened SBP response compared

to young men. No significant difference in women.

• DBP - Both sexes show no age difference in DBP response.

• During small muscle exercise • SBP - Old women show a heightened SBP response

compared to young women. No significant difference in men.

• DBP – old women show a greater DBP response compared to young women. No significant difference in men.

Question #2

Are the heightened BP responses in older individuals fitness dependent?

Does an increase in fitness level normalize or “correct” the heightened blood pressure response seen in older men and

women?

How does it compare across exercises?

Question #2: ResultsTreadmill Exercise

Men

Fitness Level

OM (LF) OM (HF)

SB

P S

lop

e (

SB

P v

s.

ME

T)

0

2

4

6

8

10

12

14

16

18

SBP

Women

Fitness Level

OW (LF) OW (HF)

SB

P S

lop

e (

SB

P v

s.

ME

T)

0

2

4

6

8

10

12

14

16

18

SBP

Systolic Blood Pressure

P = 0.20 P = 0.20

Question #2: ResultsTreadmill Exercise

Diastolic Blood Pressure

Men

Fitness Level

OM (LF) OM (HF)

DB

P S

lope (

DB

P v

s.

ME

T)

0.0

0.5

1.0

1.5

2.0

2.5

DBP

Women

Fitness Level

OW (LF) OW (HF)

DB

P S

lope

(D

BP

vs.

ME

T)

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

DBP

Question #2: ResultsKnee Kick Exercise

Men

Fitness Level

OM (LF) OM (HF)

SB

P S

lop

e (

SB

P v

s.

ME

T)

0

5

10

15

20

25

30

35

SBP

Women

Fitness Level

OW (LF) OW (HF)

SB

P S

lop

e (

SB

P v

s.

ME

T)

0

10

20

30

40

SBP

Systolic Blood Pressure

P = 0.15

Question #2: ResultsKnee Kick Exercise

Diastolic Blood PressureMen

Fitness Level

OM (LF) OM (HF)

DB

P S

lop

e (

DB

P v

s.

ME

T)

0

2

4

6

8

10

12

14

16

DBP

Women

Fitness Level

OW (LF) OW (HF)

DB

P S

lop

e (

DB

P v

s.

ME

T)

0

5

10

15

20

25

DBP

P = 0.004 P = 0.13

Question #2: Results

• Question #2 – Fitness Effect?

• During large muscle exercise • SBP - Both low fit older men and women exhibited greater

SBP responses compared to high fit, but not statistically significant.

• DBP - Both sexes show no fitness effect in DBP response.

• During small muscle exercise • SBP - Both sexes show no fitness effect in SBP response.

• DBP – low fit old men show a much higher DBP response when compared to high fit older men. No difference in women.

Question #3

Is the pressor response determined by the active muscle mass?

I.e. is the pressor response heightened with the knee extensor exercise vs. the

treadmill?

Question #3: Results

Women

Age Group

YW OW (LF) OW (HF)

SB

P S

lope (

SB

P v

s.

ME

T)

0

10

20

30

40

Treadmill

Knee Kick

Men

Age Group

YM OM (LF) OM (HF)

SB

P S

lop

e (

SB

P v

s.

ME

T)

0

5

10

15

20

25

30

35

Treadmill

Knee Kick

Systolic Blood Pressure

Question #3: Results

Diastolic Blood Pressure

Women

Age Group

YW OW (LF) OW (HF)

DB

P S

lop

e (

DB

P v

s.

ME

T)

0

5

10

15

20

25

Treadmill

Knee Kick

Men

Age Group

YM OM (LF) OM (HF)

DB

P S

lop

e (

DB

P v

s.

ME

T)

0

5

10

15

20

25

Treadmill

Knee Kick

Question #3: Results

• Question #3 – BP Response determined by the active muscle mass?

• SBP – significant mode-specific response, i.e. SBP response was more pronounced during small muscle knee kick exercise compared to the large muscle treadmill running exercise. – Except for young women group.

• DBP – Significant mode-specific response. – Except for high fit older men.

Summary• Question #1: Age Effect

– SBP - Heightened exercise SBP only with old men during treadmill and old women during the knee kick exercise.

– DBP – Greater DBP response only seen in old women during the knee kick exercise.

• Question #2: Fitness Effect– SBP – no fitness effect for both sexes and both exercises. – DBP – Heightened exercise DBP only in older men during knee kick

exercise.

• Question #3: Size of the active muscle mass – The pressor response during small muscle exercise, during knee

extension, exceeded the response seen in exercise using many large muscles, during treadmill running. • SBP – except for young women. • DBP – except for high fit older men.

Acknowledgements

Collaborators

Funding

Research Team

David Proctor, PhD (PI)

Joaquin Gonzales, PhD (Postdoc)

Sandy Smithmyer (Study Coordinator)

Julie Miedlar (Doctoral Candidate)

Seed Grant in Gerontology

Training Grants in Physiology, Gerontology

GCRC (University Park, Hershey)