CH 4


Terms in this set (...)

for an immediate increase in ATP we use
ATP-PC system and Glycolysis
we must use aerobic ATP production
when we have an increase in oxygen levels at a steady state for 1-4 min
oxygen deficit
lag in oxygen uptake at beginning of exercise
PCR system and exercise/ATP from PCR hydrolysis
the longer the exercise the more stable the linear relationship becomes
during the first 3 mins of exercise the relationship is lower
rate of glycogenolytic ATP production
upside down V shape for 3 mins
trained O2 deficit
lower O2 deficit and increase in aerobic bioenegetic capacity
decrease in lactate and H
increase in cardiovascular or muscular adaptations (bank analogy)
oxygen debt
elevated VO2 above resting during recovery, repayment for O2 deficit
Excess post exercise oxygen consumption
oxygen debt
EPOC is greater following higher intensity exercise because?
increase in body temperature and depletion of PC
increase of lactic acid and catecholamines
classical theory of removal of lactic acid following exercise states that
lactic acid became glucose in the liver
recent evidence of removal of lactic acid following exercise states that
70% is oxidized and used for heart and skeletal muscle
20% becomes glucose
10% becomes amino acids
active recovery at optimal intensity
30-40% VO2 max
Almost 100% of ATP is produced by
aerobic metabolism
Blood lactate levels are
low <1.0 mmol/L
Resting O2 consumption
0.25 L/min 3.5 ml/kg/min
Ambient Air
O2 = 20.93 CO2 = .03 Nitrogen= 79.04
Oxygen debt
Repayment for O2 deficit at onset of exercise
Excess post-exercise oxygen consumption (EPOC)
reflects that only ~20% elevated O2 consumption used to "repay" O2 deficit
"Rapid" portion of O2 debt
Resynthesis of stored PC
Replenishing muscle and blood O2 levels
"Slow" portion of O2 debt
Elevated heart rate and breathing = ↑ energy need
Elevated body temperature/Elevated epinephrine and norepinephrine = ↑ metabolic rate
lactic acid turns into glucose
Conversion of lactic acid to glucose during slow portion of O2 debt
EPOC is ________ following higher intensity exercise
EPOC following higher intensity exercise leads to
Higher body temperature
Greater depletion of PC
Additional O2 required for resynthesis
Greater blood concentrations of lactic acid
Greater level of gluconeogenesis
Higher levels of blood epinephrine and norepinephrine
Lactic acid is removed more rapidly
with light exercise in recovery and the optimal intensity is ~30-40% VO2 max
First 1-5 seconds of exercise
ATP through ATP-PC system
Intense exercise longer than 5 seconds
Shift to ATP production via glycolysis
Events lasting longer than 45 seconds
ATP production through ATP-PC, glycolysis, and aerobic systems
70% anaerobic/30% aerobic at 60 seconds
50% anaerobic/50% aerobic at 2 minutes
Prolonged exercise (>10 minutes)
ATP production primarily from aerobic metabolism
Steady-state oxygen uptake can generally be maintained during submaximal exercise
Prolonged exercise in a hot/humid environment or at high intensity
Upward drift in oxygen uptake over time due to body temperature and rising epinephrine and norepinephrine
Oxygen uptake increases _______ until maximal oxygen uptake (VO2 max) is reached
linearly; no further increase in VO2 with increasing work rate
VO2 max
"Physiological ceiling" for delivery of O2 to muscle, Affected by genetics and training
Physiological factors influencing VO2 max
Maximum ability of cardiorespiratory system to deliver oxygen to the muscle and ability of muscles to use oxygen and produce ATP aerobically
The point at which blood lactic acid rises systematically during incremental exercise
Appears at ~50-60% VO2 max in untrained subjects
Appears at 65-80% VO2 max in trained subjects
Lactate threshold
2 mmol/L,
Onset of blood lactate accumulation (OBLA levels reach 4 mmol/L)
Low muscle oxygen
hypoxia (reason for lactate threshold)
Accelerated glycolysis
NADH produced faster than it is shuttled into mitochondria
Excess NADH in cytoplasm
converts pyruvic acid to lactic acid
reasons for lactate threshold
Recruitment of fast-twitch muscle fibers
Reduced rate of lactate removal from the blood
practical uses of LT
Prediction of performance
Combined with VO2 max
Planning training programs
Marker of training intensity
Choose a training HR based on LT
Delayed-onset muscle soreness (DOMS)
24-48 hours after exercise
Physiological evidence does not support claim that
Lactate production is commonly believed to cause muscle soreness
Lactate removal
is rapid (within 60 minutes) following exercise
What does cause muscle soreness?
Microscopic injury to muscle fibers leads to inflammation
Low-intensity exercise
<30% VO2 max Fats are primary fuel
High-intensity exercise
>70% VO2 max Carbohydrates are primary fuel
"Crossover" concept
Describes the shift from fat to CHO metabolism as exercise intensity increase which is due to recruitment of fast muscle fibers and increasing blood levels of epinephrine
At low exercise intensities (~20% VO2 max)
High percentage of energy expenditure (~66%) derived from fat
total energy expended is low (3 kcal•min-1)
total fat oxidation is also low (2 kcal•min-1)
At higher exercise intensities (~60% VO2 max)
Lower percentage of energy (~33%) from fat
Total energy expended is higher (9 kcal•min-1)
Total fat oxidation is also higher (3 kcal•min-1)
Highest rate of fat oxidation
Reached just before lactate threshold
Prolonged, low-intensity exercise fuel selection
goes from carbohydrate metabolism toward fat metabolism due to an increased rate of lipolysis Breakdown of triglycerides: glycerol + FFA by enzymes called lipases
Stimulated by rising blood levels of epinephrine
"Fats burn in the flame of carbohydrates"
Glycogen is _________ during prolonged high-intensity exercise
depletion of glycogen causes
Reduced rate of glycolysis and production of pyruvate
reduced Krebs cycle intermediates
reduced fat oxidation
fats are metabolized by Krebs cycle
The depletion of muscle and blood carbohydrate stores contributes to
Ingestion of carbohydrates can improve
endurance performance
During submaximal (<70% VO2 max), long-duration (>90 minutes) exercise
30-60 g of carbohydrate per hour are required which may also improve performance in shorter, higher intensity events
Muscle glycogen
Primary source of carbohydrate during high-intensity exercise
supplies much of the carbohydrate in the first hour of exercise
Blood glucose
from liver glycogenolysis primary source of carbohydrate during low-intensity exercise
important during long-duration exercise as muscle glycogen levels decline
Intramuscular triglycerides
Primary source of fat during higher intensity exercise
Plasma FFA
converted to acetyl-CoA and enters Krebs cycle
Primary source of fat during low-intensity exercise
Becomes more important as muscle triglyceride levels decline in long-duration exercise
Proteins is broken down into amino acids because muscle
can directly metabolize branch chain amino acids and alanine
the liver can convert ______ to glucose
protein during exercise
is only a small contribution (~2%) to total energy production during exercise
May increase to 5-10% late in prolonged-duration exercise
Enzymes that degrade proteins
proteases are activated in
long-term exercise
lactate as a fuel source during exercise
Can be used as a fuel source by skeletal muscle and the heart
Can be converted to glucose in the liver
and it can be transported from one tissue to another
the cori cycle
1) Lactate produced by skeletal muscle is transported to the liver
2) Liver converts lactate to glucose (gluconeogenesis)
3) Glucose is transported back to muscle and used as a fuel