KINE 326

atp demand and atp hydrolysis

atp supply = endergonic reactions

• demand inc with

  • exercise intensity

  • muscel recruitment

  • duration of activity

  • metabolic stress

• high atp demand = cells must porduce atp quickly to mee energy req of muscle contraction and cellular functions

atp hydrolysis = exergonic

• the breakdown of atp to release energy

• fromula: atp → adp + pi + energy

• this energy powers:

  • muscle contraction (myosin heads)

  • protein synthesis, active transport

catabolism and anabolism

catabolism - breaks down carbs and fats, releasing energy (atp)

• provides energy in the form of atp to fuel muscle contractions and cellular functions

• drives exergonic reactions by releaseing energy stored in glucose, fats, and proteins

• transfers electrons to intermediary carriers → powering production of atp

• occurs during exercise due to needed exercise

anabolism - builds up proteins, glycogen, and lipids from simplier ones using energy (atp)

• is endergonic (requires energy), often fueled by atp produced during catabolism

• supports muscle growth, tissue repair, hormone production, and cell dividaion

• occurs post exercise or during sleep

main macronutrients of metabolism - CHO (carbohydrates)

• primary energy source for the brain and during high intense exercise

• broken down into glucose (primary subsrtate) and stored as glycogen

  • stored in liver and skeletal muscle

  • inc intensity and inc exercise time = more glycogen consumed in muscles

    • ex: when fat is burned, it gives a slower supply of atp (occurs in low intensity exercises), but with intense exercise, atp is burned in a fast rate. inc consumption (from s1 heads of myosin) → inc need of atp → inc in atp production = glycogen burned

  • the amont of glycogen found in the muscles depends on the your diet

    • high carb intake = more glycogen in muscles = more time before exhaustion

    • glycogen resynthesis

      • carb only - low glyocgen resynthesis

      • carb carb - medium rate of glycogen restoration

      • carb protein - high glysocgen resynthesis

        • stimulates insulin release, due to protein, aiding in msucle repair

• used in aerobic and anaerobic pathways to make atp

main macronutrients of metabolism - lipid (fats)

• MOST energy-dense macronutrients

• primarily used during rest and low-intensity exercise

• break down into fatty acids and glycerol for beta-oxidation and atp production

main macronutrients of metabolism - proteins

• NOT a primary energy source, can be used during prolonged exercise or starvation

• broken down into amino acids

• used for repair, growth, and as a last-resort energy source

pathways of energy metabolism

• phosphagen system (nonoxidative)

  • very fast, short duration

  • used during explosive movements (sprint, jump)

  • immediate atp source, very fast, short duration

• glycolytic system (nonoxidative, anaerobic (occurs outside of mitchondria))

  • greaks down glucose to produce atp

  • supports moderate duration, high intensity work

  • fast atp supply, used during high force output

• oxidative systems (aerobic)

  • uses oxygen to break down carbs (CHO) and fats

  • supplies atp for long duration, steady state activity

  • atp turnover is slower but sustainable for longer durations

ex in activities for pathways of energy metabolism

• short duration, explosive movements (kicking a football, 50-100m swim, pole valut)

  • relies heavily on phosophagen system (immediate atp, no oxygen)

  • duration 5-30 seconds

• middle distance, high intensity (400-800m sprint, 200-400m swim)

  • uses phosophagen, but relies on glycolysis for quick atp

  • duration 1-5 minutes

• long diatance, endurance events (3-6 mile run)

  • relies heavily on mitchondrial (oxidative) metabolism (fats and carbs)

  • phosphagen and glycolytic systems are low

  • duration more that 12 minutes

steady state

• occurs when oxygen uptake matches the energy demand od the aactivity

• usually reached wi 2-3 minutes of moderate exercise

• atp mostly generated by oxidative metabolism

• oxygen consumption plateaus and lactate levels stabilize

metabolic transient

• inital phase right after you start exercising

• oxygen uptake is rising, but hasnt plateaued (body is adjusting to the new energy demand)

• energy needs being met by anaerobic systems (phosphgen and glycolysis)

definition of ventilatory threshold (VT)

when breathing rate (ventilation) starts to inc disproportionately compared to oxygen consumption

what is ventilatory threshold (VT)

• a marker of aerobic capacity and how well u tolerate intensity

• linked to lactate threshold - lactate accumulates in blood faster than it can be cleared

• shows when body shifts from mainly aerobic to inc anaerobic energy production due to inadequate atp supply

• untrained inviduals typically reach vt at 50-60% vo2 max and trained inviduals at 75% vo2 max

EPOC definition

excess post exercise oxygen consumption) - refers to the inc rate of oxugen intake following exercise as the body works to restore itself to resting state

when does epoc occur

• right after exercise ends

• occurs bc the body needs extra oxygen to:

  • replenish atp and pcr (phosphocreatine) stores

  • reoxygenate blood and muscles

  • clear lactate from blood

  • lower body temp and hr

what affects epoc

• higher exercise intensity = greater epoc

• trained individuals recover faster → shorter epoc

• it is the after burn effect, allowing u to burn calories after youre done exercising

  • can last from 15 mins to 24 hours later

summary:

EPOC is influenced by how hard, how long, and what type of exercise you do.
More intensity → more disruption → more oxygen needed to restore balance → greater calorie burn after exercise

loci of fatigue

• central fatigue (brain and spinal cord level)

  • originates in the cns

  • reduces neural drive or motor unit recruitment

  • you FEEL tired, lose motivation, or cant metally push through

  • influnced by:

    • core temp (overheating)

    • mental fatigue or sleep dept

• peripheral fatigue (muscle level)

  • occurs in the muscle fibers themselves

  • reduced the muscles ability to generate force

  • causes:

    • depletion of atp, glycogen, pr pcr

    • failure in excitation contraction coupling

role of phosphates system in energy metabolism

• priamry role: rapid regeneration of atp during short, intense burst of activity (sprinting, lifting, jumping)

• does NOT require oxygen

reactions role of phosphates system in energy metabolism

• creatine kinase (ck) reaction:

  • PCr + ADP → ATP + creatine

    • uses phosphocreatine (PCr) sotred in muscles to regenrate atp

    • reaction is VERY FAST and reversible

    • supplies atp IMMEDIATELY at the onset of exercise

  • adenylate kinase (myokinease) reaction:

    • ADP + ADP → ATP + AMP

      • helps sustain atp when PCr is lwo

      • amp also stimulated glycolysis and glycogen breakdown

  • amp deaminase reaction

    • AMP → IMP + NH4

      • purpose: prevents excessive amp buildup by converting it to IMP

      • helps control acidosis, supports high intensity work by regulating amp levels, signials for energy restoration (in recovery phase)

      • IMP eventually helps resynthesize AMP later

what happens during intense exercise

• muscles neeed energy to contract → atp levels drop but body works hard to keep them from getting too low

• pcr donated phosphate to adp to make more atp (doesnt require oxygen)

• pcr levels dec fast

• as pcr dec, body uses 2 ADP molesules to make 1 atp + 1 amp

• amp builds signiling body to start glycolysis for longer energy supply

• rising amp → begin break down of glycogen and glucose

creatine kinsase

• PCr + ADP → ATP + creatine

  • purpose: rapid regeneration of atp using stored phosphocreatine (pcr)

  • reaction is VERY FAST and reversible

  • importance: primary atp source att he START fo high intensity effort

  • for short, intense exercise

  • indicator: dec pcr → in in cr and pi

adenylate kinase (myokinease) reaction:

• ADP + ADP → ATP + AMP

  • purpose: creates EXTRA atp when pcr runs low

  • amp also stimulated glycolysis and glycogen breakdown

amp deaminase reaction

purpose: prevents excessive amp buildup by converting it to IMP

helps control acidosis, supports high intensity work by regulating amp levels, signials for energy restoration (in recovery phase)

IMP eventually helps resynthesize AMP later

what happens during intense exercise

• muscles neeed energy to contract → atp levels drop but body works hard to keep them from getting too low

• pcr donated phosphate to adp to make more atp (doesnt require oxygen)

• pcr levels dec fast

• as pcr dec, body uses 2 ADP molesules to make 1 atp + 1 amp

• amp builds signiling body to start glycolysis for longer energy supply

• rising amp → begin break down of glycogen and glucose

atpase

• atp → adp + pi + energy

• purpose: enzyme responseible for atp hydrolysis - the release of energy to power muscle contraction

• location: myosin heads and other atp dependednt cellular processes

• role in phosphagen system: uses atp while other enzymes are trying to replenish atpase burns

equlibrium reactions definition

reaction where the forward and reverse rates are equal - no change in reactant or product concentrations

what are the equlibrium reactions

• creatine kinease reaction

  • pcr + adp → atp + creatine

  • direction driven by pcr, adp, atp, cr

  • at rest: favors pcr storage

  • during exercise: favors atp production

• adenylate kinase reaction

  • ADP + ADP → ATP + AMP

  • activates when adp accumulates, usually during intense effort

  • produces amp, when signals the need to ramp up glycolysis and glucogenolysis

why do equilibrium reactions matter

• respond instantly to changes in cellular energy demand

• buffer atp levels during rapid use

• allow for rapid shifts between energy states (rest, exercise, recovery)

• serves as early triggers for activating longer-term systems (glycolysis, oxidative phosphorylation)

acidosis defintion

the dec in ph in the muscle or blood, typically caused by the accumulation of hydrogen ions during intense exercise

during high intensity activity, muscles use atp fast and rely more on anaerobic glycolysis for quick atp

what does acidosis lead to

• it impairs muscle contraction by inferering with calcium release, reducing the ability of actin myosin to generate force, contributing to musclar fatigue

  • singals need for more oxidative (aerobic) pathway and recover

• enzyme inhibition: enzymes involves in energy metabolism become less effective in low pH. slows down atp production, esp from glycolysis

• neuromuscular fatigue: impars transmission of signals from nerves to muscle. feel weaker or slower

• inc breathing rate: body tries to buffer acidosis by blowing off more CO2 (acidic) throuhg hyperventilation. triggered rice in ventilation at VT

• early onset of fatigue

role of acidosis in phosphagen system:

• creatine kinase reaction conusumes an h ions when converting pcr + adp → atp + cr (helps buffer acidosis)

• once pcr is depleted, glycolysis takes over and h accumulates faster, inc acidosis

how do ATP change during intense exercise and recovery? implications for subsequent exercise?

• during exercise: slightly dec; being used for muscle contraction. body maintains atp by regenerating it with pcr and adp

• recovery: returns to baseline; oxidative metabolism restores atp

If ATP is not fully restored:

• You start your next set/workout with lower energy reserves

• Higher risk of early fatigue, reduced power output

  If ATP is fully recovered:

• Muscles are ready to generate high force again

• PCr stores restored = rapid ATP regeneration when needed

• Improved performance and delayed fatigue

how do PCR change during intense exercise and recovery? implications for subsequent exercise?

• during exercise: rapidly dec; donates a phosphate to adp to make atp via creatine kinase (main short term energy)

• recovery: gradually inc; pcr resynthesis req oxygen and happens at rest

how do ADP change during intense exercise and recovery? implications for subsequent exercise?

• during exercise: inc; atp is broken down and adp accumulates which activates adenylate kinase to regenerate atp

• recovery: dec; atp is resynthesized, adp is reused and converted back

how do AMP change during intense exercise and recovery? implications for subsequent exercise?

• during exercise: inc alot; produced by adenylate kinase. amp signals need to inc glycolysis and glycogenolysis. high amp contributed to metabolic stress and fatigue

• recovery: cleared or converted to imp; amp converts to excess amp and amp is recycled during recovery. amp drop signals reduced energy stress

implications of how do ATP, PCR, ADP, AMP change during intense exercise and recovery? implications for subsequent exercise?

• implications:

  • if you dont recover

    • low pcr = slower atp resynthesis → early fatigue

    • lactic acid build up may impair muscle function

  • if recovered

    • pcr restored → ready for explosive effort

    • atp levels stable → good performance

    • enzymes reset → metabolic systems are balanced