Exercise Physiology

1
Exercise Physiology
Krishna Asundi, PhD Research Fellow Harvard
School of Public Health (kasundi_at_hsph.harvard.edu)
Lab tel. [phone]
2
Course Schedule

• February 11th - Work, Energy and Power
• Start thinking about term paper
• February 25th Muscles, Cardiovascular and
  Respiratory Systems
• Submit topic
• March 3rd Bioenergetics and Exercise Metabolism
• Submit list of references (cite the sources
  appropriately APA writing style)
• March 10th Physiology of Training
• Submit abstract of paper
• March 31st Training for Performance
• April 7th Oral Presentations
• April 21st Oral Presentations
• April 28th Term paper deadline

3
Grading

• 35 of your class grade is from the section
• Section grade
• 10 for participation
• 30 for the class presentation
• 60 for the term paper

4
Guidelines to the term paper

• Term paper and presentation
• Paper should be rooted in primary sources
  (original references)
• Topics must be specific and focused
• e.g. Not something as general as exercise
  physiology but for example, will women
  marathoners catch up and eventually outperform
  men?
• Interpretations should hinge on science
• The paper must have a significant biological/
  biomechanics/ physiology component
• Projects can be done in pairs

5
Guidelines to the term paper

• 10-12 pages, double-spaced, size 12 font
  (excluding figures and references)
• 10-15 primary references
• Web-sources are permitted but only a very small
  portion (less that 10)
• P.S An online reference ahead of publication for
  example is not treated as a web source

6
Guidelines to the term paper

• Do not hesitate to seek feedback about paper
  topics, references etc Highly encouraged!
• References sources
• Pubmed (http//www.ncbi.nlm.nih.gov.ezp1.harvard.e
  du/entrez/query.fcgi?holdinghulib)
• You can download reference articles directly
  using the above link
• Books from Harvard libraries or elsewhere

7
Some suggested topics

• No limit to flexibility, just check with me if in
  doubt!

• Relationship between physical activity and
  osteoporosis
• Rehabilitation and exercise manuals, grounded in
  science or based on opinions?
• Historical examples of scientific studies that
  have catapulted our sporting abilities
• Is it better to eat before or after exercise?
• Underlying mechanics in muscle fatigue and
  exhaustion

8
Previous Papers

• Increasing Muscle Mass Whats the best way?
• The Health Benefits of Yoga
• A Physiological Analysis of Gender Difference in
  Athletic Performance

9
Oral presentation

• Excerpts from the term paper
• 10 minute presentations
• Details will follow

10
What is Exercise?
11
Systems involved in exercise

Musculoskeletal System Nervous
System Cardiovascular System Respiratory
System Endocrine System
12
What is Exercise Physiology

• Exercise Physiology studies the changes in the
  human body in response to physical activity
• How does the body maintain an adequate internal
  environment under the challenges presented by
  exercise?
• How does the body adapt to exercise over the long
  term?

13
Principles of Exercise Physiology

• Biological Control Mechanism
• Mechanisms by which the body maintains the
  physical and chemical parameters of the body at
  acceptable levels
• Sweating, increase heart rate, vasodilatation
• Adaptation
• Gradual changes in various systems to better
  cope with the demands of physical activity
• Muscle hypertrophy, increased capillary density,
  greater heart stroke volume

14
Work, Energy and Power
15
Forces

• The body exerts internal and external forces
  through the musculoskeletal system
• A force can be simply defined as a push or pull
• Newtons Second Law of motion says
• Force mass x acceleration
• F ma
• The units for force are Newtons (N)

16
Work

• Work is the product of force and displacement in
  the direction of the applied force
• Work Force x Displacement
• The units of work are Nm or joules (J)
• 1 J 1 Nm

17
Example - Discus Throw

• Work Force x distance
• Force 1000 N
• Distance 0.6 m
• Work 1000 N x 0.6 m
• 600 Nm
• 600 Joules

McGinnis, P. M. (1999). Biomechanics of sport and
exercise. Human Kinetics .
18
Example Weight Lifter

• Magnus first lowers the barbell and then raises
  the barbell
• The average force he exerts while lowering and
  raising the barbell is 1000 N

McGinnis, P. M. (1999). Biomechanics of sport and
exercise. Human Kinetics .
How much work did Magnus do to the barbell for
this whole lift?
19
Example Weight Lifter
Lowering Barbell F 1000 N D -70 m W -700 J
Raising Barbell F 1000 N D 70 m W 700 J
McGinnis, P. M. (1999). Biomechanics of sport and
exercise. Human Kinetics .
Total W 700 -700 0 J Magnus did 0 J of work
to the barbell
20
Work

• Work can be positive or negative
• Positive work is done when the force and
  displacement occur in the same direction
• Negative work is done when the force and
  displacement occur in opposite directions

21
Energy

• Energy is the capacity to do work
• Conservation of energy states
• Energy cannot be created or destroyed, only
  converted
• Thermal, chemical, kinetic, strain
• Muscles convert chemical energy (food) into
  thermal (heat), kinetic (motion) and strain
  (stretching of tendons) energy

22
Power

• Power is the rate of doing work
• Power
• The units of power are watts (W)
• More power means more work in less time

23
Example Box Movers

• Eli lifts 5, 100 N Boxes, from the floor to a
  shelf 1.2 meters off the ground in 60 seconds.
• Tom lifts 8, 50 N boxes from the floor to a shelf
  2 meters off the ground in 100 seconds.
• Who used more power?

24
Example Box Movers

• Eli
• Work 100 N x 1.2 m
• 120 J / box
• Total Work 120 J/box x 5 600 J
• Power 600 J / 60 sec
• 10 Watts

• Tom
• Work 50 N x 2 m
• 100 J / box
• Total Work 100 J/box x 8 800 J
• Power 800 J / 100 sec
• 8 Watts

25
Big Picture

• The body generates forces to do work to different
  body segments and external objects
• People who can do more work, faster have more
  power
• Athletic ability is defined by skill and power

26
Review

• Internal and external forces are generated by the
  musculoskeletal system of the body
• Work is the product of force and displacement
• W F x d
• Work can be positive or negative
• Energy is the capacity to do work
• Power is the rate of doing work P