Exam 2 Flashcards
Bioenergetics (Metabolism)
chemical process of converting food into energy
catabolic
breaking down larger molecules into smaller molecules
anabolic
building smaller molecules into larger molecules
glycogen
storage form of glucose in animals (stored in muscle and liver)
glycogenesis
formation of glycogen from glucose
glycogenolysis
breaking down glycogen into glucose
ATP-Pcr cycle
CK (creatine kinase) controls rate of ATP production (negative feedback system)
when ATP levels drop ADP and CK activity increases
when ATP levels increase CK activity decreases
ATP-Pcr system
stored ATP (2-3 seconds of max effort)
phosphocreatine is broken down by creatine kinase, which can be used to create ATP
last 30 sec (short, intense sprints/vertical jumps)
role of glucose in glycolysis
glucose transforms to lactate when limited amounts of oxygen are available
the role of ATP-Pcr on fatigue and how it relates to intensity and time of exercise
breakdown of ATP & PCR not primary cause of decreased muscle force and fatigue, breakdown of PC occurs, aerobic recovery period is necessary to provide energy to reform PC
high intensity bouts are accompanied by lower-intensity recovery periods
how does exercise alter these systems (ATP-Pcr)
increases in major enzymes (CK) would result in faster regeneration of ATP
in anaerobic training, some studies demonstrate increased intramuscular concentrations of ATP and PC at rest
what is lactate and how is it produced?
when cells break down carbs for energy, remaining compound bind with positively charged sodium ion or potassium ion to form the acid salt lactate
forms during anaerobic glycolysis
Basal Metabolic Rate (BMR) and what contributes to it?
minimum # of calories required for basic function at rest
body size (larger adults have more metabolizing tissue and larger BMR), amount of lean muscle tissue, amount of body fat
Resting Metabolic Rate (RMR) and what contributes to it?
of calories that your body burns while its at rest
physical activity, increased metabolic rate during exercise partially carries over when exercise stops
glycolysis (aerobic vs anaerobic)
Aerobic: slow, results in pyruvate-to-acetyly CoA-to-citric acid cycle (krebs) and electron transport of the remaining energy within original glucose molecule 2 ATP
Anaerobic: pyruvate-to-lactate formation with the release of about 5% of energy within the original glucose molecule, more ATP production 2 ATP, 3 ATP from glycogen
krebs cycle
pyruvate in the absence of oxygen converted to lactate
oxidative phosphorylation
ETC, breaking down hydrogens to produce huge amounts of ATP
fate of pyruvate during aerobic metabolism
pyruvate is transported to mitochondria. inside mitochondria pyruvate undergoes oxidative decarboxylation and produces acetyl CoA
fate of pyruvate during anaerobic metabolism
pyruvate undergoes reduction which produces lactate
EPOC
post exercise oxygen consumption
amount of oxygen required to restore body to its normal resting level of metabolic functions (homeostasis)
oxygen deficit
difference between total oxygen consumed during exercise and total that would have been consumed had steady-rate oxygen uptake been achieved at the start of exercise
rate limiting factors
fluid loss/electrolyte depletion and maintaining adequate reserves of liver glycogen for CNS function & muscle glycogen to power exercise
why is fat oxidation increased walking vs cycling?
when walking, your weight is supported o your ankles activating more muscles. more muscles activated = the greater fat oxidation.
why might femals have an enhanced fat oxidation vs males?
females typically have more adipose tissue, more tissue you have, more you can burn
what is the respiratory quotient?
carbs, fats, and proteins require different amounts of O2 for complete oxidation. based on the byproducts of metabolism (CO2/H2O)
RQ = CO2 produced/O2 consumed
respiratory quotient (RQ) carbs
1.0 (6 CO2/6 O2)
respiratory quotient (RQ) protein
0.83 - 0.85 (63 CO2/77 O2)
respiratory quotient (RQ) fat
0.7 (16 CO2/23 O2)
lactate threshold
point at which, during incremental exercise, lactate builds up in the blood system, at a level that is higher than resting values
how does exercise alter lactate threshold?
increased ability to metabolize lipid
increase enzymes of the Krebs cycle and ETC
increased capillary density and #
triglyceride
stored form of fat
what does the body emphasize for short, high intensity activities?
anaerobic metabolism
first 30 seconds: ATP-PC System
30 sec - 3 minutes: Glycolysis
what does the body emphasize for activities for longer than 3 minutes?
aerobic metabolism
aerobic pathways
more efficient production of energy from a given substrate like glucose
can use carbs and fats and proteins (when necessary)
primary source of energy at rest and extended, low intensity activities
ETC
hydrogen channels in the membrane allow hydrogen ions to flow down their concentration gradient, which activates ATP synthase
lipid catabolism
stored fat serves as most plentiful source of potential energy
fat becomes primary energy fuel for exercise/recovery when intense, long-durations exercise depletes blood glucose and muscle glycogen
4x ATP produced than glucose
lipid mobilization
hormone sensitive lipase stimulates triacylglcerol (TAG) breakdown into its glycerol (1) & fatty acid components (3)
energy releases when TAG stored in muscle fibers degrades to glycerol and fatty acids
beta oxidation
process of converting FFAs to acetyl CoA before entering Krebs cycle
requires up-front expenditure of 2 ATP
lipid oxidation
acetyl-CoA enters Krebs cycle
endocrine effects (aerobic metabolism)
epinephrine, norepinephrine, glucagon, and growth hormone increase lipase activation and subsequent lipolysis and FFA mobilization from adipose tissue
hormonal release triggered by exercise stimulates adipose tissue lipolysis to further augment FFA delivery to active muscle
amino acids metabolism typically smaller except
extreme dieting increases protein breakdown
high protein diets can increase use of proteins for energy
long-term endurance activity activates proteases
maximal exercise
VO2 max occurs when oxygen uptake plateaus or increases only slightly with additional increases in exercise intensity
lipid & glucose interaction (insulin)
insulin inhibits hormone-sensitive lipase, decrease free fatty acids and transports glucose into skeletal muscles
ingesting high-carb meal/drink decreases triglyceride metabolism and increases carb metabolism
“crossover” effect
describes the shift from fat to CHO metabolism as exercise intensity increases (activating fast muscle fibers and increasing blood levels of epinephrine)
low intensity exercise
<30% VO2 max
fats are primary fuel during prolonged low intensity exercise
high intensity exercise
> 70% VO2 max
carbohydrates are primary fuel
blood lactate threshold
occurs when muscle cells can neither meet energy demands aerobically nor oxidize lactate at its rate of formation
occurs at higher % of trained aerobic capacity compared to untrained
fast-twitch (type II) role
rapid contraction speed and high capacity for anaerobic ATP production on glycolysis; highly active in change-of-pace/stop-and-go activities
type IIa: high aerobic capacity
type IIx: lactate
slow twitch (type 1)
generates energy through aerobic pathways
active in continuos activites
exercise below lactate threshold
increased capillary density
increased mitochondrial density
ability to oxidize hydrogens more efficiently
delay in onset of lactic acid production
training above lactate threshold
if production outweighs clearance, lactate is produced
heat production
all of bodys metabolic processes result in heat production
calorie (kcal) is basic unit of heat measurement
heat production increases, oxygen production increases
direct calorimetry
measures energy expenditure via heat production
indirect calorimetry
all energy releasing reactions in humans depend on xygen use, so measuring oxygen consumption during physical activity provides an indirect yet accurate estimate of energy production
two types:
1. closed-circuit spirometry
2. open-circuit spirometry
closed circuit
simple method that directly measures O2 uptake but has limited practical applications
subject breathes 100% O2 from spirometer, rebreathes only gas in spirometer
potassium hydroxide in circuit absorbs exhaled CO2
drum attached to spirometer revolves at known speed to record O2 uptake from changes in systems total volume
open circuit
simple and practical way to measure O2 uptake and CO2 production to infer energy expenditure
inhales ambient air with constant composition
changes in %O2 and CO2 in expired air compared with % inspired ambient air indirectly reflect ongoing process of energy metabolism
bag technique, portable spirometry, computerized instrumentation
FatMax
what % of VO2 max are we going to be burning fat
TDEE
Total Daily Energy Expenditure
10% thermic effect of feeding (food intake, cold stress, thermogenic drugs)
15-30% thermic effect of physical activity (duration & intensity)
60-75% resting metabolic rate (fat-free body mass, gender, thyroid hormones)
five factors that influence TDEE
- physical activity
- diet-induced thermogenesis
- calorigenic effect of food on exercise metabolism
- climate
- pregnancy
energy required to utilize 100 kcals each (pure sugar, fat, starchy carbs, protein, fibrous carbs)
pure sugar: 2-3 kcals
fat: 5-7 kcals
starchy carbs: 10-12 kcals
protein: 25 kcals
fibrous carbs: 75 kcals
training effect
increased O2 kinetic chain mechanics
