The Pressor
  Response:
Large vs. Small
Muscle Exercise
      Dustin Grinnell
  Physiology Department
Pennsylvania State U...
Background
         The challenge of exercise
• During exercise, cardiovascular system must:
  – Deliver adequate oxygen t...
Background
              Arterial Blood Pressure
• Pressure: force exerted by
  blood against arterial walls
• Systolic
  ...
Background
       Blood Pressure with Exercise
• 120/80 mmHg at rest
• 200/60 mmHg at max aerobic exercise
Introduction
• The Pressor Response
     - This blood pressure response to exercise is called the
       “pressor response...
Aim of the Study
• It was the aim of this study to:

       1) Explore the blood pressure response to two
       modes of ...
Methods
   Large vs. Small Muscle Exercise




VO2max Test         Knee Extension Exercise
Methods
• The Proctor lab’s “fitness study”
      -recruited 56 normotensive healthy men and women.
      -Subjects fell i...
Results
                          Pressor Response to Large Muscle Treadmill
                                            R...
Results
                            Pressor Response to Small Muscle Knee
                                           Exten...
Results
Large Muscle Exercise vs. Small Muscle Exercise
                                              Systolic Blood Press...
Results
Large Muscle Exercise vs. Small Muscle Exercise
                                        Mean Arterial Blood Pressu...
Results
• Pressor Response
  • In response to both large muscle and small muscle exercise all
    groups showed significan...
Summary
  Why is the pressor response exaggerated in small muscle exercise
                       when compared to large?
...
Clinical Significance
• Why is an exaggerated blood pressure response a problem?

• Cardiovascular Risk
   -   The effects...
Clinical Significance
• Bond, et at.
    – showed a higher pressor response to physical stress is found in
      normotens...
Conclusions
• The pressor response during small muscle exercise,
  during knee extension, exceeds the response seen in
  e...
Future Directions
• Individual pressor responses may differ between the
  fitness study’s 6 groups.

• Factors that can al...
Acknowledgements
Research Team
David Proctor, PhD (PI)
Joaquin Gonzales, PhD (Postdoc)
Sandy Smithmyer (Study Coordinator)...
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The Pressor Response Large Vs. Small Muscle Exercise

  1. 1. The Pressor Response: Large vs. Small Muscle Exercise Dustin Grinnell Physiology Department Pennsylvania State University
  2. 2. Background The challenge of exercise • During exercise, cardiovascular system must: – Deliver adequate oxygen to working muscles – Remove waste products (lactate, CO2) – Regulate body temperature – Maintain arterial pressure • In other words, maintain homeostasis
  3. 3. Background Arterial Blood Pressure • Pressure: force exerted by blood against arterial walls • Systolic – Pressure generated as blood is ejected from the heart during systole • Diastolic – Pressure during ventricular relaxation
  4. 4. Background Blood Pressure with Exercise • 120/80 mmHg at rest • 200/60 mmHg at max aerobic exercise
  5. 5. Introduction • The Pressor Response - This blood pressure response to exercise is called the “pressor response” Topic: Today I am going to talk about the blood pressure response to two modes of dynamic exercise and why we see a heightened response with small muscle dynamic exercise.
  6. 6. Aim of the Study • It was the aim of this study to: 1) Explore the blood pressure response to two modes of dynamic exercise. - The first exercise model used was the treadmill running exercise, which employs the use of many large muscles. - The second exercise was a one-leg knee extension exercise, which contracts only a few small muscles. 2) Understand if the pressor response was determined by the active muscle mass.
  7. 7. Methods Large vs. Small Muscle Exercise VO2max Test Knee Extension Exercise
  8. 8. Methods • The Proctor lab’s “fitness study” -recruited 56 normotensive healthy men and women. -Subjects fell into 6 groups based on age and fitness level. -Young men, young women, low fit old men, high fit old men, low fit old women, and high fit old women. • All subjects performed: - a large muscle exercise, a VO2max treadmill running test - a small muscle exercise, a one-legged knee extensor exercise. • Variables recorded: -Heart rate -systolic blood pressure -diastolic -blood pressure -mean arterial blood pressure was calculated post- exercise.
  9. 9. Results Pressor Response to Large Muscle Treadmill Running Systolic Blood Pressure Mean Arterial Blood Pressure 70 35 60 30 50 25 d S B P (m m H G ) d M A P (m m H g ) 40 20 30 15 20 10 10 5 0 0 YM YW O M (LF ) O W (LF ) O M (H F ) O W (H F ) YM YW O M (L F ) O W (L F ) O M (H F ) O W (H F ) A g e G ro u p A g e G ro u p dS B P dM AP
  10. 10. Results Pressor Response to Small Muscle Knee Extension Systolic Blood Pressure Mean Arterial Blood Pressure 60 35 30 50 25 40 d S B P (m m H G ) d M A P (m m H g ) 20 30 15 20 10 10 5 0 0 YM YW O M (L F ) O W (L F ) O M (H F ) O W (H F ) YM YW O M (L F ) O W (L F ) O M (H F ) O W (H F ) A g e G ro u p A g e G ro u p dSBP dM AP
  11. 11. Results Large Muscle Exercise vs. Small Muscle Exercise Systolic Blood Pressure vs. MET 180 170 S B P (m m H g ) 160 150 140 130 0 2 4 10 12 14 16 MET T re a d m ill - S lo p e = 8 .0 K n e e K ic k - S lo p e = 2 6 More pronounced systolic blood pressure response during small muscle exercise
  12. 12. Results Large Muscle Exercise vs. Small Muscle Exercise Mean Arterial Blood Pressure vs. MET 125 120 115 M A P (m m H g ) 110 105 100 95 90 85 0 2 4 10 12 14 16 MET T re a d m ill - S lo p e = 4 K n e e K ic k - S lo p e = 1 6 More pronounced mean arterial blood pressure response during small muscle exercise
  13. 13. Results • Pressor Response • In response to both large muscle and small muscle exercise all groups showed significant increases in: -Systolic blood pressure -Mean arterial blood pressure • Mode-specific Response • The blood pressure response was more pronounced during the small muscle knee extension exercise compared to the large muscle treadmill running exercise.
  14. 14. Summary Why is the pressor response exaggerated in small muscle exercise when compared to large? • Treadmill Running – An aerobic activity like running, involves the rhythmic and alternative contraction and relaxation of many muscles which causes systemic vasodilatation and a reduction in total peripheral resistance and a large drop in blood pressure. • Knee Extension – During a knee kicking exercise, which involves the contraction and relaxation of only a few small muscles only local, not systemic, vasodilatation is seen, which results in little or no change to total peripheral resistance and much higher pressor response.
  15. 15. Clinical Significance • Why is an exaggerated blood pressure response a problem? • Cardiovascular Risk - The effects of an increased, or exaggerated pressor response to exercise, in healthy people has important consequences in cardiovascular disease such as coronary heart disease. • Literature - Many studies have looked at this exaggerated blood pressure response to graded dynamic exercise in healthy people and have found it to be a predictor of future hypertension and risk of cardiovascular mortality.
  16. 16. Clinical Significance • Bond, et at. – showed a higher pressor response to physical stress is found in normotensives with a family history of hypertension. • Stewart, et al. – showed that the exaggerated blood pressure response is related to impaired endothelial vasodilator function. • Chang et al. – showed that patients with exercise-induced hypertension have impaired endothelium-dependent vasodilatation. • Jae et al. – showed that inflammation may be associated with an exaggerated blood pressure to exercise.
  17. 17. Conclusions • The pressor response during small muscle exercise, during knee extension, exceeds the response seen in exercise using many large muscles seen during treadmill running. • This exaggerated blood pressure response seen in small muscle exercise has important cardiovascular implications.
  18. 18. Future Directions • Individual pressor responses may differ between the fitness study’s 6 groups. • Factors that can alter the blood pressure response to exercise are: • Age • Sex • Fitness levels. • It is the aim of an upcoming paper, and the seminar talk to present the data concerning these results.
  19. 19. Acknowledgements Research Team David Proctor, PhD (PI) Joaquin Gonzales, PhD (Postdoc) Sandy Smithmyer (Study Coordinator) Julie Miedlar (Doctoral Candidate) Collaborators GCRC (University Park, Hershey) Funding Training Grants in Physiology, Seed Grant in Gerontology Gerontology

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