KIN 3515 Lecture : Unit 2 Notes
15 Mar 2019
School
Course
Professor
Exercise metabolism 9/19/2013 4:03:00 PM
Exercise Metabolism
• The study of how the body provides the energy necessary to
generate the desired power output.
Fatigue
• The inability to maintain a desired power output
• Can occur in many different ways
o Can fatigue after 10 seconds or 2 hours
o Causes are different
• If you cant do it, you are fatigued
o Kind of an all or none type of a type
ATP
• Source of energy in the body (i.e. ATP hydrolysis liberates energy)
4 Major Sites of ATP Hydrolysis during Muscular Work
1. Cross-bridge cycle (a.k.a. actomyosin interaction)
2. SR Ca++ pumps
3. Sarcolemma Na+/K+ pumps
4. Neuronal membrane Na+/K+ pumps
• ATP that is broken down, the energy that’s coming out of that, we
don’t utilize that much of it
Does ATP Depletion Cause Fatigue?
• Cost of walking = ~6 kcal/min 6 kcal/min x 15 min = 90 kcal
• ATP contains 10 kcal / mole
• 90 kcal÷10 kcal / mole=9 moles of ATP needed to walk 15 minutes
• 1 mole of ATP = 500 g
• 9 moles x 500 g = 4500 g of ATP needed to walk 15 minutes
• 0.005 moles of ATP per kg of muscle (due to cell volume
limitations)
• 9 ÷ 0.005 = 1800 kg (~4000 lbs or 2 tons) of muscle to walk
15 minutes
• Do we store enough ATP to do anything?
o No we do not provide our ATP through stored ATP
• SINCE ATP CANNOT CROSS CELL MEMBRANES FROM WHERE
DOES THE 9 MOLES OF ATP COME?
• FATIGUE IS NOT RELATED TO ATP DEPLETION BUT INSTEAD
IT IS RELATED TO THE RATE OF ATP RESYNTHESIS!!!
o What we do, set amount of ATP
▪ We break it apart and put it back together→”very
ecological”
• IN OTHER WORDS FATIGUE OCCURS WHEN THE RATE OF ATP
RESYNTHESIS IS LESS THAN THE RATE OF ATP USAGE (or
BREAKDOWN or HYDROLYSIS)
o We fatigue because we don’t make it fast enough as we use it
• The rate at which we break it down is designated by the work that
you are doing
o To do work at a certain rate is a set rate, same for everyone
o The way to make energy is different per person
Graph
• Speed vs. Time of running
• Faster you go, shorter you can go
• Slope of line – rates
• Body’s ability to resynthesize ATP→3 different rates to synthesize
ATP (3 different slopes)
o Will slow down when you meet or exceed that rate
Graph
1. The body has three different systems to maintain ATP balance.
(maintaining ATP balance a.k.a. ATP buffering)
2. These systems differ in their rate of ATP resynthesis.
3. Therefore, the primary cause of fatigue is the inability to match
the rate of ATP resynthesis with the rate of ATP hydrolysis.
o (i.e. when you fatigue, power output slows down until it can
match an ATP resynthesis rate.)
• These systems differ
o Ex. Oxidative – working in first 30 seconds but not important
• All 3 systems are working all the time its just the importance of
their contribution
o All 3 systems are working, just not necessarily working at
their maximum pace
Maximal Power and Capacity of the Three Energy Systems
• Immediate
o Max Power (kcal/min) – 36
o Max Capacity (stored kcal) – 11
• Glycolysis
o Max Power (kcal/min) – 16
o Max Capacity (stored kcal) – 15
• Oxidative
o Max Power (kcal/min) – 10
o Max Capacity (stored kcal) – 480
Remember!
1. All 3 metabolic systems (pathways) are operating at all times.
2. The rate of a particular system and its relative contribution
varies with the work demand.
• Chart
Immediate or “Borrowing” Energy Systems
• “Faster to borrow than to earn”
• Consists of two parts :
1. ATP-CP or Phosphagen System
▪ This reaction uses the enzyme creatine phosphokinase
or CPK (aka Creatine Kinase or CK) (works faster)
CPK
ADP + CP =========> ATP + C
2. Myokinase System
▪ This reaction uses the enzyme myokinase (a.k.a.
adenylate kinase). (comes into play when other one
slows down)
myokinase
ADP + ADP ===========> ATP + AMP
• NOTE: A build up of AMP can force the reaction to work backwards,
so you end up producing ADP not ATP. (want to keep AMP levels
low)
myokinase
ATP + AMP ===========> ADP + ADP
• Therefore the muscle cells must do one of the following to keep
[AMP] low.
1. FAST MYOSIN containing muscle cells
AMP deaminase
AMP + H2O ============> IMP + NH3 (ammonia)
(IMP = inositol monophosphate)
2. SLOW MYOSIN containing muscle cells
Document Summary
Exercise metabolism: the study of how the body provides the energy necessary to generate the desired power output. Atp: source of energy in the body (i. e. atp hydrolysis liberates energy) 15 minutes: do we store enough atp to do anything, no we do not provide our atp through stored atp, since atp cannot cross cell membranes from where. Does the 9 moles of atp come: fatigue is not related to atp depletion but instead. It is related to the rate of atp resynthesis!: what we do, set amount of atp, we break it apart and put it back together very ecological , in other words fatigue occurs when the rate of atp. Resynthesis is less than the rate of atp usage (or. Graph: speed vs. time of running, faster you go, shorter you can go, slope of line rates, body"s ability to resynthesize atp 3 different rates to synthesize.
