Physiological Effects Of Exercise Flashcards
Skeletal Muscle
Strength is mainly determined by size
Cross sectional area of fibers in a muscle is proportional to the strength that can be generated
Long fibers good for rapid movement
Short fibers good for large forces
Fiber types
Slow twitch (Type 1)
Oxidative
Red
Prolonged endurance activity
Fast twitch Type 2a
Red
Either endurance or rapid force
Quickly fatigue
Fast twitch Type 2b
White
Rapid force production
Quickly fatigue
Exercise contractions
To increase muscle strength – muscle fiber cross sectional area
Isometric - no movement
Isotonic - concentric and eccentric
Endurance exercise training
Increased mitochondrial function
Hypoxia inducible factors (HIFs) involved in gene control of red muscle cell production and regulation of glycolytic enzymes.
Increased Haemoglobin concentration
Individual variation
Individuals vary in proportions of different fiber types
Training does not significantly change proportions of fiber types
Athletes find the sport that fits their abilities
Smoking and lifestyle
Smoking reduces cross sectional area Of muscles
A 1500m run
Energy production X8 in first 3 minutes
Increase in;
– Consumption of cellular fuel
– Consumption of oxygen
– Production of carbon dioxide – Heat
Creatine phosphate
ATP + Creatine —> creatine phosphate and ADP which is broken down by creatine kinase into creatine and ATP which is then used for muscle contraction
Glycolysis
2ATP + 2 Pyruvate
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Citric acid / Krebs Cycle
1 ATP + 3NADH + 1FADH2
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Electron transport chain
By far most energy produced by this oxidative process
Between 20-30 ATP
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Lactate
Pyruvate
/. \
Acetyl co a. Lactic acid
|. |
Mitochondria Liver
|. |
ATP. ATP
Lactate
Increase in lactate build up in athletes
Triathletes slow build up
longer aerobic component to ATP production before increased glycolysis
Gluconeogenisis
Liver and kidneys
SEE LECTURE SLIDES
Intense short term exercise
10-15 seconds
– Creatine phosphate
– ATP
Up to 2 minutes
– Glycogen to glucose-6-phosphate
Several minutes
– Oxygen debt
– Lactic acid build up
– About 2L of oxygen required to replenish ATP and creatine phosphate
Longer less intense exercise
Glycogen from circulation
Glucose from plasma
Hepatic glucose production increases
– Short term glycogenolysis
– Longer term gluconeogenesis • Muscle proteolysis
• Glucagon and Insulin • Fatty acid release
Oxygen deficit
VO2max: Oxygen usage under maximal aerobic activity
EPOC: Excess post exercise oxygen consumption
Recovery phase
Fast component
– Resting levels of ATP and CP restored
Slow component
– lactic acid converted to glucose in liver
– Lactic acid converted to pyruvic acid
Respiratory system during exercise
To meet the increased oxygen demand
– Increase in ventilation rate
– Increased in tidal volume
Control of respiration
Psychological
CNS
CO2 levels
H+ levels
O2 levels
Pulmonary stretch receptors
Peripheral joint receptors
Body temperature
Changes in Blood gasses
Arterial 02 and venous CO2 do not change significantly during exercise
– Respiratory system can provide adequate aeration
Oxygen consumption
Oxygen consumption increases
Similar rate for first few seconds
Reaches steady state where lactate acid accumulation is minimal
Other factors like fuel availability limit exercise
VO2max When steady state oxygen consumption does not increase with work intensity.
V02max
Increases in exercise past V02max result in
increased lactic acid accumulation
Age
– Decreases after 25
Activity
– Improves with activity
Sex
– Lower for females
Can be improved with training
Alveolar diffusion
Oxygen and Carbon Dioxide diffusion capacity increases with exercise
– increase from 23 mlmin-1 to 48 mlmin-1 from rest to maximal exercise for non athlete.
– 80 mlmin-1 in a rower at maximal exercise
Related to increase in perfusion more that ventilation
