Regulation of High Intensity Exercise

primary energy sources during high intensity exercise

ATP-PCr system depletes quickly, Glycogen to lactate system used most, O2 systems steadily increase

Phosphocreatine, carbs, lipids and proteins can all make

ATP in the ATP-ADP cycle

3 inorganic phosphates make up

ATP + an adenosine

products of ATP-ADP cycle

adenosine diphosphate (ADP), 1 inorganic phosphate and FREE ENERGY

ATP, ADP, and AMP have phosphates with

high energy bonds

direct source of energy

only ATP

indirect sources of energy

ADP (in most cases), carb, fat, protein, alcohol, phosphocreatine

humans burning 2,000kcal a day makes and breaks about

45kg of ATP/day (but only 0.1kg of ATP on the body at one time)

Energy rich component of ATP

triphosphate subunit contains 2 phosphoric acid anhydride linkages which upon hydrolysis release high amounts of energy

ATP- turnover

40-45 kg/day

while ATP is made into free energy by myosin ATPase, phosphocreatine is made into ATP by

creatine kinase

breakdown of PCr is a ________ process

anaerobic

because our diet is high in phosphorus, supplementation with

creatine alone produces more phosphocreatine in muscle

how do we make/manufacture creatine

amino acids in our diet from meat

PCr is the fastest production of ATP, its only __ step

1 enzymatic

delta G of phosphocreatine hydrolysis is

more negative than that of ATP hydrolysis

one advantage of creatine phosphate is that it is much more

diffusible compared to ATP itself (so it can go where it is needed quickly)

why is there a finite amount of creatine phosphate in cell

its very osmotic, would bring too much water in

creatine kinase isozymes

brain = BB-CK, muscle isozyme = MM-CK, mitochondrial 1 = ubiquitous mtCK, mitochondrial 2 = sarcomeric mtCK

which isozyme is right at the myofilaments

MM-creatine kinase

mitochondrial creatine kinase located at the

membranes in mitochondria

phosphocreatine is a buffer

not much of a drop in cellular ATP (but phosphocreatine drops dramatically and Creatine increases drastically)

phosphocreatine recovery takes

2 minutes

what does PCr recovery indicate about recovery times in interval training and resistance training?

if rest is less than 2 minutes, PCr is not recovered

re-synthesis of phosphocreatine is dependent on

oxygen supply (when blood flow is occluded, it does not recover)

maximum rate of ATP energy production for PCr

9 mM/kg/s

we can use ADP from breakdown of ATP to make

more ATP

This 2ADP pathway is catalyzed by the enzyme

adenylate kinase, also called myokinase

note that this 2ADP pathway has what kind of energy

POSITIVE Gibbs energy (+delta G) so it only works by mass action = build up of ADP during exercise (so we don't make much of our ATP this way)

what is the fate of AMP in skeletal muscle during exercise?

it is degraded to ammonia and hypoxanthine

in AMP degradation, hypoxanthine comes out in the

blood, its a source of oxidation (production of free radicals) in the body - anti-oxidant system counters this

in AMP degradation, NH3 goes to

liver to convert to urea

lactate and ammonia thresholds

both lactate and ammonia have thresholds that look similar, however, ammonia occurs around VO2 max, while Lactate can be trained and occur anywhere from 50-95% max

where does carbohydrate for High intensity energy come from during exercise?

endogenous sources (primarily) and exogenous sources (small amount)

endogenous sources of carb

glycogenolysis (breaking down of glucose) in muscle

exogenous sources of carb

gut-derived glucose - what you eat (blood sugar)

glycogenolysis

breakdown of glycogen to enter glycolysis

glycogen

chains of glucose formed together

2 forms of glycogen

a) active form and b) inactive

glycogen phosphorylase

Enzyme that breaks down glycogen into glucose. more importantly, it breaks down glycosidic linkages and detaches molecules of glucose 1-phosphate.

debranching enzyme

takes branches off glycogen. When there's 4 glucose molecules left on a glycogen, it carries 3 glucose residues from one branch to another

enzymes needed to degrade glycogen

phosphorylase and debranching enzyme

glycogen phosphorylase has a very complicated regulation...

allosteric and covalently regulated

takeaway from allosteric regulation of glycogen phosphorylase

we don't want to be making glycogen while we're breaking glycogen down

allosteric regulation of glycogen phosphorylase

Stimulated by ↑AMP

Inhibited by ↑ATP

fructose 6phosphate

important regulatory enzyme for PFK

ATP investment phase of glycolysis

first 5 steps

ATP earning phase of glycolysis

last 5 steps

allosteric regulation of PFK negative regulators, at REST, turn down acidity increases

Citrate, ATP, H+, PCr

allosteric regulation of PFK, positive regulators,

AMP, Pi, ADP, Fructose-2-6-biP

why do we make lactate

it regenerates NAD, which allows glycolysis to continue under heavy under heavy exercise conditions, (otherwise NAD is made slowly from end of ETC in mitochondria and NAD is not where it needs to be)