1
Q
What is the fraction of O2 in the air?
A
0.2093
This fraction represents the proportion of oxygen in the atmosphere.
2
Q
What is the partial pressure of O2 at sea level?
A
159 mmHg
Calculated using the fraction of O2 multiplied by the barometric pressure.
3
Q
According to Dalton’s law, what is the total pressure of a gas mixture?
A
The sum of the pressure that each gas would exert independently
This law is fundamental in understanding gas mixtures.
4
Q
What is the partial pressure of CO2 in the air?
A
0.3 mmHg
This value is derived from the fraction of CO2 multiplied by the barometric pressure.
5
Q
What is the average altitude of Mammoth Lakes?
A
7,880 Feet
This is the highest incorporated city in California.
6
Q
What happens to pulmonary ventilation at high altitude?
A
Increases both respiratory rate and tidal volume
This response is due to lower arterial PO2 sensed by peripheral chemoreceptors.
7
Q
What is the effect of increased pulmonary ventilation on PCO2?
A
PCO2 drops
This drop in PCO2 leads to increased blood pH, causing respiratory alkalosis.
8
Q
What limits oxygen delivery at altitude?
A
The diffusion gradient
The shape of the oxyhemoglobin dissociation curve and respiratory alkalosis help maintain hemoglobin saturation.
9
Q
Fill in the blank: The total pressure of a gas mixture can be calculated using the formula: P_air = _______ + PCO2 + PN2.
A
PO2
This formula represents the contributions of different gases to the total pressure.
10
Q
What are the three systems of ATP production?
A
- ATP-PC
- Glycolysis
- Aerobic metabolism
Each system is most active under different exercise conditions.
11
Q
What does direct calorimetry measure?
A
Heat production and energy production
It has pros and cons in measuring energy expenditure.
12
Q
What does indirect calorimetry measure?
A
Energy expenditure (V̇O2, V̇CO2)
It uses the Haldane Transformation and Respiratory Exchange Ratio (RER).
13
Q
What is the Respiratory Exchange Ratio (RER) indicative of?
A
The relationship of carbon atoms and the amount of oxygen needed
It varies for different substrates like fat and carbohydrates.
14
Q
What is the Basal Metabolic Rate (BMR)?
A
Minimum energy requirement for living
It relates to fat-free mass (FFM) and other influencing factors.
15
Q
True or false: The Resting Metabolic Rate (RMR) is the same as BMR.
A
FALSE
RMR and BMR differ in their definitions and measurement conditions.
16
Q
What is V̇O2 max?
A
Maximum oxygen uptake during exercise
It indicates aerobic capacity and performance potential.
17
Q
What happens to lactate threshold in trained versus untrained athletes?
A
Occurs at a higher percentage of VO2 max in trained athletes
It influences endurance performance.
18
Q
What is the Cori Cycle?
A
The process of converting lactate back to glucose
It allows for lactate to be used as a fuel source during exercise.
19
Q
What are the heat exchange mechanisms?
A
- Radiation
- Conduction
- Convection
- Evaporation
Each mechanism contributes to heat loss during exercise.
20
Q
What is the role of the anterior hypothalamus?
A
Thermoregulation during exercise
It integrates signals to produce efferent effects.
21
Q
What happens to core temperature during exercise?
A
Increases with exercise intensity
The pattern of increase can differ based on measurement methods.
22
Q
What is the effect of heat acclimation on heart rate?
A
Lower heart rate response during prolonged exercise in the heat
Acclimation requires specific heat exposures.
23
Q
What is hypoxia?
A
A deficiency in the amount of oxygen reaching tissues
It can occur at high altitudes.
24
Q
What happens to pulmonary ventilation at altitude?
A
Increases due to lower oxygen availability
This leads to respiratory alkalosis.
25
What is the **oxyhemoglobin dissociation curve**?
Describes how hemoglobin's oxygen binding affinity changes with partial pressure
## Footnote
It shifts at different altitudes.
26
What is the **partial pressure of oxygen** at sea level?
Approximately 21% of barometric pressure
## Footnote
It decreases as altitude increases.
27
What is the **slow component of O2 uptake kinetics**?
A gradual increase in oxygen uptake during prolonged exercise
## Footnote
Influenced by muscle fiber recruitment.
28
What is **EPOC**?
Excess post-exercise oxygen consumption
## Footnote
It reflects the oxygen deficit during exercise.
29
What is the **lactate threshold**?
The exercise intensity at which lactate begins to accumulate in the blood
## Footnote
It is a key indicator of endurance performance.
30
What are the **two pathways** that interact to provide energy for exercise?
* Aerobic pathways
* Anaerobic pathways
## Footnote
All three energy systems interact for all activities, but one system often dominates for a given task.
31
In **short-term, high-intensity activities**, which energy system contributes more?
Anaerobic energy systems
## Footnote
These activities rely more on anaerobic pathways for energy production.
32
For **long-term, low to moderate-intensity exercise**, the majority of ATP is produced from _______.
aerobic sources
## Footnote
This reflects the efficiency of aerobic metabolism over extended periods.
33
What is **direct calorimetry** used for?
* Measuring substrate metabolism efficiency
* Measuring resting metabolic rates
## Footnote
It measures heat production to estimate energy expenditure.
34
List two **pros** of direct calorimetry.
* Accurate over time
* Good for resting metabolic measurements
## Footnote
These advantages make it useful for specific metabolic assessments.
35
List two **cons** of direct calorimetry.
* Expensive
* Slow
## Footnote
Additional factors like exercise equipment and sweat can create errors in measurements.
36
What does **indirect calorimetry** estimate?
Total body energy expenditure based on O2 used and CO2 produced
## Footnote
It measures respiratory gas concentrations to derive energy expenditure.
37
Define **VO2**.
Volume of O2 consumed per minute
## Footnote
It reflects the rate of oxygen consumption during metabolism.
38
Define **VCO2**.
Volume of CO2 produced per minute
## Footnote
It indicates the rate of carbon dioxide production during metabolism.
39
What is the **Haldane transformation** used for?
Calculating the volume of inspired air from the volume of expired air
## Footnote
It is based on the constancy of nitrogen volumes.
40
The **respiratory exchange ratio (RER)** is the ratio between rates of _______ and _______.
CO2 production, O2 usage
## Footnote
This ratio helps determine the type of fuel being oxidized during metabolism.
41
What is the RER for **fat oxidation**?
0.70
## Footnote
This indicates a higher reliance on fat as a fuel source.
42
What is the RER for **carbohydrate oxidation**?
1.00
## Footnote
This indicates a higher reliance on carbohydrates as a fuel source.
43
True or false: The RER is accurate for protein oxidation.
FALSE
## Footnote
RER may be inaccurate when assessing protein metabolism.
44
What can cause an **inaccurate RER** reading during exercise?
* Lactate buildup
* Gluconeogenesis
## Footnote
These factors can affect CO2 exhalation and skew the RER results.
45
What is **metabolic rate**?
Rate of energy use by body
## Footnote
Based on whole-body O2 consumption and corresponding caloric equivalent.
46
At rest, what is the approximate **RER** and **VO2**?
RER ~0.80, VO2 ~0.25 L•min-1
## Footnote
At rest, metabolic rate is approximately 2,000 kcal•day-1.
47
Define **Basal Metabolic Rate (BMR)**.
Rate of energy expenditure at rest in supine position
## Footnote
Minimum energy requirement for living, affected by factors like fat-free mass, body surface area, age, stress, hormones, and body temperature.
48
What is the normal range for **Resting Metabolic Rate (RMR)**?
1,200 to 2,400 kcal/day
## Footnote
Similar to BMR but easier to measure, does not require stringent standardized conditions.
49
What is the total daily metabolic activity range for normal individuals?
1,800 to 3,000 kcal/day
## Footnote
Competitive athletes may expend up to 10,000 kcal/day.
50
What is the **slow component of O2 uptake kinetics**?
At high power outputs, VO2 continues to increase
## Footnote
More type II (less efficient) fiber recruitment requires more VO2 to reach the same power output.
51
What is **VO2 drift**?
Upward drift during prolonged exercise
## Footnote
Observed at power outputs well below lactate threshold, possibly due to increased ventilation and circulating catecholamines.
52
Define **VO2max**.
Point at which O2 consumption does not increase with further increase in intensity
## Footnote
Best single measurement of aerobic fitness, but not the best predictor of endurance performance.
53
How is **VO2max** expressed?
In L•min-1
## Footnote
Normalized for body weight in ml O2•kg-1•min-1 for accurate comparison across different body sizes.
54
What are the VO2max values for untrained young men and women?
Untrained young men: 44 to 50, untrained young women: 38 to 42
## Footnote
Sex difference due to women's lower fat-free mass and hemoglobin.
55
What is the **lactate threshold**?
Point at which blood lactate accumulation increases markedly
## Footnote
Occurs when lactate production rate exceeds lactate clearance rate, indicating endurance exercise potential.
56
A higher **lactate threshold** indicates what?
Better endurance performance
## Footnote
For athletes with the same V•O2max, a higher lactate threshold predicts better performance.
57
What is the **ventilatory threshold** used for?
As a surrogate measure for lactate threshold
## Footnote
It helps estimate lactate threshold through respiratory responses.
58
What happens when excess lactic acid is combined with sodium bicarbonate?
Results in excess sodium lactate, H2O, CO2
## Footnote
Lactate and CO2 accumulate simultaneously, refining lactate threshold estimation.
59
What factors contribute to lactate accumulation during exercise?
* Low muscle oxygen (hypoxia)
* Accelerated glycolysis
* Excess NADH in cytoplasm
* Recruitment of fast-twitch muscle fibers
* Reduced rate of lactate removal
## Footnote
These factors contribute to lactate accumulation during exercise.
60
What is the **classical theory** regarding lactate?
Majority of lactate converted to glucose in liver
## Footnote
Recent evidence shows 70% of lactate is oxidized, used as a substrate by heart and skeletal muscle.
61
What percentage of lactate is converted to glucose through gluconeogenesis?
20%
## Footnote
The remaining lactate is oxidized or converted to amino acids.
62
What is the **optimal intensity** for lactate removal following exercise?
~30–40% V•O2max
## Footnote
Light exercise helps remove lactate more rapidly during recovery.
63
What effect does lactate accumulation have on muscle pH?
Causes a decrease in muscle pH (acidosis)
## Footnote
If pH < 6.9, it inhibits glycolytic enzymes and ATP synthesis.
64
What is the **Cori cycle**?
Lactate produced by skeletal muscle is transported to the liver, converted to glucose
## Footnote
Glucose is then transported back to muscle and used as fuel.
65
How can lactate be used as a **fuel source** during exercise?
* Converted to acetyl-CoA and enters Krebs cycle
* Converted to glucose in the liver
## Footnote
Lactate can serve as an energy source for skeletal muscle and the heart.
66
What are the **practical uses** of the lactate threshold?
* Prediction of performance
* Planning training programs
* Marker of training intensity
## Footnote
Training heart rate can be chosen based on lactate threshold.
67
What is the **estimation method** for anaerobic effort?
Excess post-exercise O2 consumption (EPOC)
## Footnote
EPOC is used to assess the anaerobic effort during and after exercise.
68
During maximal anaerobic exercise, almost 100% of ATP is produced by **which metabolism**?
anaerobic metabolism
## Footnote
Phosphagen System then Glycolysis
69
What is the **resting O2 consumption** rate?
0.25 L•min-1 or 3.5 ml•kg-1•min-1
## Footnote
This rate indicates the baseline oxygen consumption at rest.
70
ATP production increases immediately, and oxygen uptake increases rapidly, reaching steady state within _______.
1–4 minutes
## Footnote
After steady state, ATP requirement is met through aerobic ATP production.
71
What are the initial pathways for ATP production during exercise?
* ATP-PC system
* Glycolysis
## Footnote
These pathways provide immediate energy before aerobic metabolism takes over.
72
What does **oxygen deficit** represent?
O2 demand > O2 consumed in early exercise
## Footnote
This occurs when anaerobic pathways are used for ATP production.
73
What is the term used for the repayment of O2 deficit at the onset of exercise?
Oxygen debt
## Footnote
This term was introduced by A.V. Hill.
74
What is the **rapid component** of EPOC responsible for?
* Resynthesis of stored PC
* Replenishing muscle and blood O2 stores
## Footnote
This occurs immediately after exercise ends.
75
Factors contributing to EPOC include elevated heart rate and breathing, elevated body temperature, and elevated _______.
epinephrine and norepinephrine
## Footnote
These factors increase metabolic rate during recovery.
76
What is the **lactate threshold**?
Point at which blood lactate accumulation increases markedly
## Footnote
It is a good indicator of potential for endurance exercise.
77
At what percentage of **VO2max** does blood lactate typically rise in untrained subjects?
~50–60% VO2max
## Footnote
Trained subjects experience this at higher work rates (65–80% VO2max).
78
The **interaction of aerobic and anaerobic systems** is indicated by what?
Lactate production rate > lactate clearance rate
## Footnote
This interaction is crucial for understanding endurance performance.
79
True or false: A higher lactate threshold indicates **better endurance performance**.
TRUE
## Footnote
For athletes with the same VO2max, a higher lactate threshold predicts better performance.
80
What is the primary purpose of **heat acclimation**?
Induces biologic adjustments that reduce the negative effects of heat stress
## Footnote
Heat acclimation develops through repeated heat exposures that elevate core and skin temperatures and provoke profuse sweating.
81
List the factors that influence the **magnitude of biologic adaptations** induced by heat acclimation.
* Intensity
* Duration
* Frequency
* Number
## Footnote
These factors determine how effective heat acclimation will be for an individual.
82
True or false: **Exercise training in a temperate climate** can replace the benefits of heat acclimatization.
FALSE
## Footnote
While exercise training reduces physiologic strain in the heat and improves exercise capabilities, it cannot substitute for heat acclimatization.
83
What happens to heat acclimation if it is not maintained by repeated heat exposure?
It gradually disappears
## Footnote
Heat acclimation is transient and requires ongoing exposure to maintain its benefits.
84
What are the three main areas of **biologic adjustments** mediated by heat acclimation?
* Integrated changes in thermoregulatory control
* Fluid balance
* Cardiovascular responses
## Footnote
These adjustments help the body cope better with heat stress during exercise.
85
What physiological effects does heat acclimation have on **core temperature and heart-rate responses** during exercise heat stress?
Reduces negative effects of heat stress
## Footnote
Heat acclimation leads to better management of core temperature and heart rate during exercise in hot conditions.
86
Fill in the blank: Heat acclimation develops through repeated heat exposures that are sufficiently stressful to elevate both _______ and skin temperatures.
core temperature
## Footnote
This elevation is crucial for inducing the necessary adaptations.
87
What is **hypobaria**?
A reduced barometric pressure at altitude
## Footnote
Hypobaria is a key term in understanding altitude physiology.
88
Define **hypoxia**.
A low PO2 in the air
## Footnote
Hypoxia can significantly affect physical performance at high altitudes.
89
What does **hypoxemia** refer to?
Low PO2 in the blood
## Footnote
Hypoxemia is critical for assessing oxygen availability in the body.
90
At what altitude is there **no effect** on wellbeing or performance?
Below ~1640 feet
## Footnote
This altitude is considered safe for most individuals.
91
What is the impact of **low altitude** (~1640-6560 feet) on performance?
No effect on wellbeing; performance can be impacted in events greater than 1500 meters
## Footnote
Acclimation can help overcome performance decrements.
92
What are the effects of **moderate altitude** (~6560-9840 feet)?
* Effects on wellbeing in unacclimated people
* Decreased maximal aerobic capacity and performance
## Footnote
Performance may or may not be restored with acclimation.
93
What defines **high altitude** (~9840-18000 feet)?
Adverse health effects in a large percentage of people and performance decrements even after acclimation
## Footnote
High altitude poses significant risks to unacclimated individuals.
94
What are the **severe hypoxic effects** associated with?
Extreme altitude (+18000 feet)
## Footnote
Extreme altitude can lead to life-threatening conditions.
95
According to **Dalton's law**, what is the total pressure of a gas mixture equal to?
The sum of the pressure that each gas would exert independently
## Footnote
This law is fundamental in understanding gas behavior in mixtures.
96
Calculate the partial pressure of **O2** in the air given its percentage is 20.93%.
159 mmHg
## Footnote
Calculation: 0.2093 x 760 mmHg = 159 mmHg.
97
What happens to **pulmonary ventilation** at altitude?
Increases both respiratory rate and tidal volume
## Footnote
Increased ventilation is a response to lower arterial PO2.
98
What causes **respiratory alkalosis** at altitude?
Increased pulmonary ventilation causes PCO2 to drop
## Footnote
This increase in blood pH helps prevent further hyperventilation from low PO2.
99
What is the **greatest regulatory challenge** imposed on the human circulatory system according to Loring B. Rowell?
The combination of upright posture, heat stress, and exercise
## Footnote
This challenge occurs under conditions of normal daily life.
100
What is the primary means of **heat loss during exercise**?
Evaporation
## Footnote
It accounts for 80% of heat loss during prolonged exercise.
101
What are the **heat exchange mechanisms** mentioned?
* Radiation
* Conduction
* Convection
* Evaporation
## Footnote
These mechanisms describe how the body loses or gains heat.
102
What percentage of **heat loss at rest** is attributed to radiation?
60%
## Footnote
Radiation is a significant method of heat loss at rest.
103
Fill in the blank: The body loses _______ kcal heat per liter of sweat evaporated.
0.58 kcal
## Footnote
This conversion is crucial for understanding heat loss through sweating.
104
What happens to **blood flow** during vasoconstriction?
Reduces flow of warm blood to the body’s cooler surface
## Footnote
This mechanism helps redirect blood to the warmer core.
105
What role does the **hypothalamus** play in thermoregulation?
* Anterior hypothalamus: Responds to increased core temperature
* Posterior hypothalamus: Responds to decreased core temperature
## Footnote
These responses include sweating and shivering to regulate body temperature.
106
What is the estimated caloric heat loss from **evaporation** during prolonged exercise?
12.0 kcal/min
## Footnote
This represents 80% of total heat loss during prolonged exercise.
107
What is the effect of **shivering** on heat production?
Generates metabolic heat
## Footnote
Shivering is a response to cold that increases heat production.
108
True or false: **Conduction** is the primary method of heat loss during prolonged exercise.
FALSE
## Footnote
Evaporation is the primary method, while conduction contributes less.
109
What factors influence the **evaporation rate**?
* Temperature and relative humidity
* Convective currents around the body
* Amount of skin surface exposed
## Footnote
These factors determine how effectively the body can lose heat through evaporation.
110
What happens when you **wipe sweat away**?
Reduces evaporative heat loss
## Footnote
Wiping sweat can decrease the body's ability to cool itself through evaporation.
111
What is the role of **vasoconstriction** in heat gain?
Reduces flow of warm blood to body’s cooler surface
## Footnote
Redirects blood to the warmer core to conserve heat.
112
What generates **metabolic heat** during cold stress?
Shivering
## Footnote
Muscular activity increases heat production in response to cold.
113
Which hormones increase **heat production** at the cellular level?
* Epinephrine
* Norepinephrine
* Thyroxine
## Footnote
These hormones are released by the adrenal medulla and stimulate metabolism.
114
What is the function of the **anterior hypothalamus**?
Responds to increased core temperature
## Footnote
Initiates sweating and increases skin blood flow for heat loss.
115
What does the **posterior hypothalamus** respond to?
Decreased core temperature
## Footnote
Triggers shivering and norepinephrine release to increase heat production.
116
What happens to **core temperature** during exercise?
Increases as a function of the metabolic rate
## Footnote
Core temperature rises almost immediately at the onset of exercise.
117
As exercise intensity increases, what happens to **body temperature**?
Linear increase in body temperature
## Footnote
Core temperature is proportional to active muscle mass.
118
What is the effect of **ambient temperature** on heat production during exercise?
Heat production remains constant
## Footnote
However, evaporative heat loss increases as ambient temperature rises.
119
What are the **heat-dissipating reflexes** elicited by rising core temperature?
* Increased sweating
* Increased skin blood flow
## Footnote
These reflexes help to balance heat production and dissipation.
120
What is the relationship between **core temperature** and metabolic rate during exercise?
Core temperature increases almost immediately with metabolic rate
## Footnote
As exercise continues, heat dissipation balances heat production.
121
Substrate Metabolism Efficiency
40% Energy = ATP 60% Energy = Heat
122
Direct Calorimetry
Heat and Energy Production - Can be measured in calorimeter - Water flows through wall - Body temperature increases water and air temp
123
Pros of Direct Calorimetry
- Accurate over time - Good for resting metabolic measurements
124
Cons of Direct Calorimetry
- Expensive and slow - Exercise equipment adds extra heat - Sweat creates errors in measurement - Not practical
125
Indirect Calorimetry
estimates body energy based on O2 used, CO2 produced
126
Indirect Calorimetry: How is it measured?
Measures volumes of O2 and CO2 inspired and expired (Rate of prodiction)
127
Haldane Transformation
Allows V of inspired air to be directly calculated from V of expired air, based on constancy of V2 volumes
128
Haldane Transformation Equation
V of inspired N2= V of expired N2
129
Respiratory Exchange Ratio
O2 used during metabolism depends of type of fuel being oxidized
130
RER Formula
R=VCO2/VO2
131
RER for Fat
0.70
132
RER for Carbohydrate
1
133
Limitations of Indirect Calorimetry
- CO2 production may not = CO2 exhalation - RER inaccurate for protein oxidation - RER near 1 may be inaccurate when lactate build up
134
Metabolic Rate
Rate of energy use by body
135
Metabolic Rate at Rest
2000 Kcal/day
136
RER at Rest
0.80
137
VO2 Max at Rest
0.25 L/Min
138
Basal Metabolic Rate (BMR)
Rate of energy expenditure at rest
139
Factors Influencing BMR
1. Body surface area 2. Age 3. Stress 4. Hormones 5. Body Temp
140
How is BMR related to Fat Free Mass
kcal x kg FFM x min
141
Resting Metabolic Rate (RMR)
Similar to BMR (within 5-10%) but easier to measure
142
How is RMR different from BMR
RMR does not require standardized conditions
143
Normal Caloric Range
1200-2400 kcal/day
144
Total Metabolic Activity Normal Range
1800-3000 Kcal/day
145
Total Metabolic Activity Athlete Range
Up to 10000 kcal/day
146
Energy Expenditure During Submaximal Aerobic Exercise
Slow component of O2 uptake kinetics, more type II fiber recruitment (less efficent)
147
VO2 Drift
Upward drift during prolonged exercise, observed at power outputs below lactate threshold
148
VO2 Max
Maximal O2 uptake
149
How much training is required before you see plateau in VO2 max?
8 to 12 weeks
150
How do athletes improve performance after VO2 max plateaus?
More training
151
Units for VO2
Expressed in LxMin-1
152
VO2 Normalized for Body Weight
More accurate comparison for different body sizes
153
Energy Expenditure During Maximal Anaerobic Exercise
No activity 100% aerobic or anaerobic
154
What type of metabolism is dominant at rest?
Aerobic metabolism dominant at rest
155
Resting Blood Lactate
Less than 1.0 mmol L-1
156
Resting Oxygen Consumption
0.25 LxMin-1, 3.5 ml x Kg-1 x Min-1
157
O2 Deficit
Shortfall of oxygen for body's energy demand at the start of exercise
158
Excess Post Exercise Oxygen Consumption
Elevated O2 consumption used to repay O2 deficit
159
Rapid Portion of O2 Debt
Resynthesis of stored PC, replentishing muscle and blood O2 stores
160
Slow Portion of O2 Debt
Elevated heart rate, breathing, body temp, epinephrine and norepinephrine, conversion of lactate to glucose
161
Metabolic Responses to Short Term Intense Exercise: First 5 Seconds
ATP through ATP-PCR system
162
Metabolic Responses to Short Term Intense Exercise: Longer than 5 Seconds
Shift to ATP production via glycolysis
163
Metabolic Responses to Short Term Intense Exercise: Longer Than 45 Seconds
ATP production through ATP-PC, glycolysis, aerobic systems, shift towards more aerobic systems
164
Lactate Threshold
Point at which blood lactate rises systematically during incremental exercise
165
Where does lactate threshold appear in untrained vs trained athletes?
50-60% for untrained, 65-80% in trained
166
Why can we use ventilatory threshold as a surrogate for lactate threshold?
Lactate and CO2 accumulate simultaneously
167
What mechanisms explain lactate threshold?
1. Low muscle oxygen 2. Accelerated glycolysis 3. Fast twitch fiber recruitment 4. Reduced rate of lactate removal from the blood
168
Accelerated Glycolysis
- NADH produced faster than it is shuttled into the mitochondria - Excess NADH in cytoplasm converts pyruvate to lactate
169
Recruitment of Fast Twitch Fibers
LDH in fast fibers promotes lactate formation
170
Classical Theory of Removal of Lactate
Majority of lactate converted to glucose in liver
171
Removal of Lactate: Recent Evidence
- 70% of lactate is oxidized - 20% converted to glucose - 10% converted to amino acids - Excretion in urine and sweat is negligible
172
How can we remove lactate more rapidly?
Light exercise in recovery
173
What happens to blood pH if lactate is not cleared?
Blood pH will go down, this is because converts to lactate + H+, H+ will accumulate
174
Practical uses of lactate threshold?
Predication of performance and planning training programs
175
How can lactate be used as fuel?
Lactate can be used after it's been converted to acetyl coA and enters krebs cycle
176
What tissues can use converted lactate?
Skeletal and heart muscle
177
Cori Cycle
How lactate is converted to glucose in the liver
178
Heat Gain Mechanisms
Metabolic Heat, Environmental heat
179
Heat Loss Mechanisms
Radiation, Conduction, Convection, Evaporation
180
Radiation
Transfer of heat via infrared rays, 60% of heat loss at rest
181
Conduction
Heat loss due to contact with another surface
182
Convection
Heat transferred to air or water
183
Evaporation
Heat from skin converts water (sweat) to water vapor (gas), 20-25% of heat loss at rest
184
Heat Gain: Vasculature Adjustments
Vasoconstriction, reduces flow of warm blood to body cooler surface, redirects it to the warmer core
185
Heat Gain: Muscular Activity
Shivering generates metabolic heat
186
Heat Gain: Hormonal Output
Epinephrine and Norepinephrine increases heat production at cellular level, Thyroxine increases resting metabolism
187
Anterior vs Posterior Hypothalamus
Anterior responds to increased core temp commencement of sweating and increased blood flow, Posterior responds to decreased core temp shivering and norepinephrine release and decreased skin flow
188
Thermal Events: What happens as exercise increase?
Heat production increases, linear increase in body temp, higher net heat loss
189
Thermal Events: As ambient temperature increases
Heat production remains constant, lower convective and radiant heat loss, higher evaporative heat loss
190
Core Temp Response to Exercise
Core temp increases as a function of metabolic rate, increases almost immediately at onset
191
What type of heat exposures are needed for heat acclimation to occur?
Needs heat exposure that is sufficiently stressful to elevate both core and skin temperatures as well as provoke profuse sweating
192
Biological Adjustments that mediate heat acclimation
Integrated changes to thermoregulatory control, fluid balance, and cardiovascular responses
193
Magnitude of biologic adaptations induced by heat acclimation depends largely on what?
Intensity, duration, frequency, number
194
How long does it take to get the full benefits of heat exposure?
About 12 days
195
Hypobaria
reduced barometric pressure at altitude
196
Hypoxia
low PO2 in the air
197
Hypoxemia
low PO2 in the blood
198
Altitude and Performance: Sea Level
no effect of altitude
199
Altitude and Performance: Low altitude
no effect on wellbeing but performance can be impacted in events over 1500 meters, can be overcome with acclimation
200
Altitude and Performance: Moderate Altitude
effects on wellbeing in unacclimated people and decreased maximal aerobic capacity and performance likely, may or may not be overcome with acclimation
201
Altitude and Performance: High Altitude
adverse health effects in large percentage of people and performance decrements even after acclimation
202
Altitude and Performance: Extreme Altitude
severe hypoxic effects
203
How and why is pulmonary ventilation increased at altitude?
Respiratory rate and tidal volume are increased, increase in ventilation is proportional to the level altitude
204
Respiratory Alkalosis: What happens to PO2 and blood pH?
Increased pulmonary ventilation causes PCO2 to drop, blood pH increases
205
How does a change in PCO2 help to prevent further hyperventilation?
Decrease in PCO2 triggers negative feedback loop to slow breathing
206
Pulmonary Diffusion at altitude
Oxygen delivery mainly limited by the lesser diffusion gradient
207
What limits oxygen delivery at altitude?
The lower PO2 means fewer binding sites on the hemoglobin get saturated
208
Effects of Acute Hypoxia (Rest)
- Increase in ventilation - Leftward shift in oxyhemoglobin dissociation curve - Stimulation of peripheral chemoreceptors - Respiratory alkalosis - Decreased plasma volume - Increased heart rate - Decreased stroke volume - Increased cardiac output - Increased blood pressure - Increased basal metabolic rate
209
Effects of Acute Hypoxia (Exercise)
- Increased vasodilation - Increased heart rate - Increased cardiac output - Decreased stroke volume - Increased VO2 - Increased lactate - Decreased blood pH - Greater use of carbohydrates
210
VO2 as Altitude Increases
VO2 max decreases
211
Hemoglobin concentrations in men that live chronically at different elevations
Increases proportionally with increases in elevation
SDSU ENS 304
flashcards
Decks in class (4)
# Cards
