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Lecture 4

PSY333H1 Lecture Notes - Lecture 4: Job Satisfaction, Social Class, Arcuate Nucleus

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Nevena Simic

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Health Psychology: Lecture 4 May 28 th
, 2012
Health-Enhancing Behaviours- Chapter 4:
Physical activity: any skeletal muscle contraction that results in an increased energy
- Any physical activity (even fidgeting) will use energy and burn calories
Exercise: repetitive physical activity or movement aimed at improving or
maintaining fitness or health.
Four components of physical activity:
1. Type: identifies the physiological systems used in a particular activity (aerobic,
strength, endurance, flexibility)
2. Frequency: describes how much activity is performed over a period of time.
3. Intensity: describes load imposed on physiological systems. (Physiological load:
how much our systems have to do to control the load, climbing stair is more of a
load than a flat surface)
4. Duration: temporal length of physical activity.
Does type matter? :
Many different types of exercise or physical activity…but physiologically there are
5 forms of exercise
Resistance related:
1. Isometric exercise: contract muscle group against immovable object without
movement in body (improves muscle strength) holding the subway rails, and
plank position.
2. Isotonic exercise: place resistance on muscles by moving muscle groups; e.g.
weightlifting (improves strength & endurance) push up
3. Isokinetic exercise: place resistance that overloads muscle group through complete
range of motion with variable resistance; need special equipment (best for strength
and endurance) change in resistance, putting weights on back while doing push
Other two forms are
1. Aerobic
2. Anaerobic
Energy for exercise comes from burning glucose and fatty acid.
- Can be in the presence of oxygen or not
Aerobic Exercise
- Sustained exercise, prolonged oxygen (O2) use
- High intensity, long duration, high endurance

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- Stimulates and strengthens heart and lungs improves body’s O2 usage
- Ex) Jogging, bicycling, swimming
Anaerobic Exercise
- High-intensity, short-duration, low-endurance
- Create deficit in O2
- Limited resources
- Sprint, running fast over short distance
Exercise Physiology
Ability to perform physical work is dependent upon the ability of the muscle to
transform chemical energy into mechanical energy
How exercise works
Muscles: source of energy that keeps everything going is Adenosine triphosphate
Biochemical way to store and use energy
- Adenine nucleotide bound to three phosphates
- Energy stored in the bond between the second and third phosphate groups
Our muscle groups are made out of individual strands of muscle. One strand is
made up of many strands and than in those strand there is two proteins called actin
and myosin and these help our muscles to contract.
How does body create ATP?
Several different systems to create ATP
Work together in phases
- Different forms of exercise use different systems, so a sprinter is getting
ATP in a completely different way from a marathon runner
ATP comes from three different biochemical systems in the muscle, in this order:
- Phosphagen system
- Glycogen-lactic acid system
- Aerobic respiration
Phosphagen System
Muscle contains a high-energy phosphate compound called creatine phosphate
Phosphate group is removed from creatine kinase, and is transferred to ADP to
form ATP
ATP levels and creatine phosphate levels= phosphagen system
- Supply energy needs of working muscle at a high rate, but only for 8 to 10

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Glycogen-Lactic Acid System
Muscles have big reserves of a complex carbohydrate called glycogen (chain of
glucose molecules)
Cell splits glycogen into glucose uses anaerobic metabolism (anaerobic means
“without oxygen”) to make ATP and a byproduct called lactic acid from the
12 chemical reactions take place to make ATP under this process, so it supplies
ATP at a slower rate than phosphogen system
- Produce enough ATP to last about 90 seconds
It is slower than the phosphogen system because there are far many steps and
exercise is limited and availability is limited.
Aerobic Respiration
When oxygen is present, glucose can be completely broken down into carbon
dioxide and water in a process called aerobic respiration
Glucose can come from three different places:
- Remaining glycogen supplies in the muscles
- Breakdown of the liver’s glycogen into glucose, which gets to working
muscle through the bloodstream
- Absorption of glucose from food in the intestine, which gets to working
muscle through the bloodstream
Can also use fatty acids from fat reserves in muscle and the body to produce ATP
In extreme cases (like starvation), proteins can also be broken down into amino
acids and used to make ATP
Aerobic respiration would use carbohydrates first, then fats and finally proteins
Produces ATP at the slowest rate of the three systems
Supply ATP for several hours or longer
Does type matter:
Sustained nature of aerobic exercise produces health benefits
Other forms of exercise are satisfying in their own way, but have less effect on
overall fitness
- Affect short-term glycogen stores instead of long-term energy conversion
A note on calories:
Number of calories in a food is a measure of how much potential energy that food
A gram of carbohydrates has 4 calories, a gram of protein has 4 calories, and a
gram of fat has 9 calories
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