Exercise Physiology Chapter 3

Accumulation of Lactate in Children

- blood lactate levels during submax and maximal exercise are lower in children - peak lactate values after max exercise have a positive rectilinear increase with age - this increase in about 50% for boys between 6-14 - children have a faster transition time for metabolites (La- and H+) from the muscle to blood; thus La- peaks sooner after exercise - rate of elimination time is the same - children have lower maximal power output and can recover more quickly

Lactate Thresholds in Children

- children work relatively harder (at a higher %VO2max) than adults at the same lactate level

Availability and Utilization of ATP-PC in children

- goal resting stores of ATP per kg of wet muscle weight appear the same for children and adults - resting PC is slightly lower for children; thus the total amount of energy that can be generated from this source is lower - children have a faster intramuscular PC restoration and recovery half-times after exercsies

Male vs. Female - mechanical power and capacity

- males produce higher absolute work output

The amount of lactic acid/lactate produced depends on what five things?

- muscle contraction - enzyme activity - muscle fiber type - SNS activation - insufficient oxygen

Male vs Female - availability and utilization of ATP-PC

- neither the local resting stores of ATP per kg of muscle nor the utilization of ATP-PC during exercise vary between sexes - males have more total energy available from phosphagen sources due to muscle mass differences

Mechanical Power and Capacity in Children

- peak power and peak power per kg of BW is lower in prepubertal boys and girls - peak values seem to occur in the late thirties for the legs and late twenties in the arms

Male vs Female - Accumulation of Lactate

- resting levels of lactate are the same for both sexes - LT's are the same when expressed as a % of VO2max, but absolute workload is higher for males - lactate concentrations are the same for a given relative workload or percentage of VO2max above the lactate thresholds - females are generally doing less in terms of an absolute workload

Field Tests to Measure Anaerobic Metabolism

- vertical jump tests (height jumped) - work not power is calculated; however, height of jump and peak power highly correlated, so acceptable indicator of anaerobic alactic power - sprints, shuttles, mid-distance runs

Problems with lactic acid accumulation

- when hydrogen ions dissociate form lactic acid, causing the blood to become more acidic - pain: resulting hydrogen ions accumulate and stimulate pain in the nerve endings in the muscle - performance decrement: metabolic fatigue and muscular fatigue

Lab procedures to measure ATP-PC and lactate When are they recored? What are they measured/reported as?

-chemical analysis of muscle biopsy specimens or blood samples -after exercise because it takes time for lactate to enter the bloodstream (5-10 mins) -millimoles per liter or milligrams per 100 ml of blood

5 factors that have an influence on lactate removal

1) the initial post exercise concentration of lactate: the higher the concentration, the faster the rate of removal 2) if individual foods a rest recovery or exercise recovery (passive vs active recovery) - quicker with active recovery 3) the intensity of the exercise recovery - just below individuals LT1 4) modality of the exercise used in the recovery phase may influence the optimal percentage of VO2max at which removal occurs 5) whether the recovery exercise is continuous or intermittent - quicker with continuous

What type of activities use anaerobic glycolysis?

1,500 meter speed skating 200-800 meter sprint wrestling round

Anaerobic metabolism (ATP-PC and LA) predominate in exercise lasting between ___-___ minutes

1-2

By _______ minutes of exercise, ATP production from anaerobic and aerobic is about ________.

1-2 equal

The ATP-PC system contributes 100% down to 40% of total energy supply within about _______ seconds

1-5

4 theories regarding children's inability to function at high anaerobic levels for activities lasting 15 seconds - 2 minutes and/or requiring large outputs

1. Muscle Enzyme Theory 2. Muscle Characteristics Theory 3. Sexual Maturation Theory 4. Neurohormonal Theory

During the transition from rest to exercise, energy is supplied by what 4 things?

1. Oxygen transport and utilization 2. Utilization of oxygen stores in capillary blood and on myoglobin 3. The splitting of stored ATP-PC 4. Anaerobic glycolysis, associated with the production of lactic acid

Elevated metabolism after exercise is considered to be caused by what 6 things? which is most important?

1. Restoration of ATP-PC stores 2. Restoration of oxygen stores 3. Elevated cardiovascular-respiratory function 4. Elevated hormonal levels 5. Elevated body temperature** 6. Lactate removal

Individuals can work at 100% VO2 max for _____ minutes

10

The ATP-PC system predominant for activities lastings ______ seconds or less

10

Individuals can work at 80% of VO2 max for________ minutes

120

Half-life of lactate

15-25 minutes

Most PC depletion occurs in the first ________ secs of exercise; ATP is maintained at the expense of PC

20

Individuals can work at 95% of VO2 max for ______ minutes

30

full clearance of lactate

30-60 minutes

Individuals can go all out for ____ mins or less

5

Glycolysis contributes about 55-20% of total energy supply from about _________ to ________ seconds

5-300

Individuals can work at 85% of VO2 max for ________ minutes

60

Anaerobic metabolism (ATP-PC and LA) contributes equally to aerobic at about ______ seconds

75

Non-metabolic CO2

CO2 formed in the blood (specifically the RBC) as a result of buffering the H+ from lactic acid - called non-metabolic because it does not result from the immediate breakdown of an energy substrate

T or F: anaerobic metabolic processes are not important prior to aerobic oxidation

False; anaerobic metabolic processes contribute to dynamic activity at 40-60% of VO2 max

When ATP demand exceeds that of the phosphagen system and aerobic system, what is used to produced ATP?

Fast (anaerobic)

What type of activity is the metabolic process Alactic Anaerobic Metabolism used in primarily? How long is it used?

High-intensity, Very short duration - initial form of required energy - takes place in first 10 seconds of max muscle contractions; little, if any, takes place after 20 seconds

Alternate name for Anaerobic Glycolysis

Lactic Acid System

The longer the duration, the more important the _______ system becomes

O2

Alternate name for Aerobic Oxidation

O2 system

___________ is the predominant process of lactate clearance both during and after exercise

Oxidation

Excess Postexericse Oxygen Consumption (EPOC)

Oxygen consumption during recovery that is above resting values

Muscle Enzyme Theory in Children

PFK is 2.5-3 times lower (a rate-limiting enzyme of glycolysis) and this lowered activity may indicate a decrease in the ability to produce lactic acid - glycogen as a substrate and LDH are both lower and in children than adults

Which metabolic process is an index of cardiorespiratory power?

aerobic oxidation (O2 system)

Short runs of 4-15 secs measures

alactic anaerobic power/capacity

Wingate Anaerobic Test (WAT)

all out ride for 30 seconds against resistance based on body-weight predominantly anaerobic

Lactate Thresholds (LT)

also known as anaerobic or ventilatory thresholds - points on the linear-curvilinear continuum of lactate accumulation that appear to indicate sharp rises, often labeled as the first (LT1) and second (LT2) lactate thresholds

Energy is primarily produced in the lactic anaerobic metabolic process through what two ways

anaerobic glycolysis: glycolytic aerobically: oxidative

The presence of lactic acid does not indicate lack of oxygen; it reflects the use of the __________ __________ pathway for ATP production

anaerobic glycolytic

runs at faster speeds indicate increased ______________ ______________

anaerobic power/capacity

When does the oxygen deficit occur?

at the onset of all activity

Mean Power (MP)

average power exerted during short duration (30 sec) work

Where does lactate travel intracellularly?

between cytoplasm (where it is produced) and mitochondria

Where does lactate travel extracellularly?

between tissues

Where is lactate produced?

cytoplasm

Alactic Anaerobic Metabolism

does not require oxygen and does not produce lactic acid - once produced, ATP is stored in muscle for 2-3 seconds as PC (3x ATP amount)

Anaerobic Glycolysis

does not used oxygen, but does result in lactic acid production

ATP-PC becomes smaller proportion of total energy as ____________ increases

duration

All three systems (ATP-PC, LA, O2_ are involved in providing ___________ for all exercise durations

energy

Tests of anaerobic power and capacity

energy system capacity energy system power

Supramaximal exercise

exercise in which the energy requirement is greater than what can be supplied aerobically by VO2 max

________ ________ are proportionally more PC than ATP compared to slow-twitch

fast-twitch fibers

Three fiber types in ATP-PC system

fast-twitch glycolytic fast-twitch oxidative glycolytic slow-twitch oxidative

lactate in the liver is recycled into _______ through _____________

glucose gluconeogenesis

The liver prefers to make glycogen from lactate through __________

glyconeogenesis

When activity begins, oxidation __________ rate so that it can supply necessary ATP and will continue until __________ is reached

increases max limit (Vo2max)

ATP and PC levels in muscles during constant-load supramax exercise lasting 3 mins or less: indicate if it increases or decreases: muscle lactate venous lactate ATP PC

increases (2-15mmolxL-1) increases (1-10mmolxL-1) decreases (5-3mmolxL-1) decreases (16.5-5mmolxL-1)

the production and clearance of lactate is directly related to ________ and ________ of exercise

intensity duration

Lactate blood circulation

intermuscularly (skeletal cells) cardiac cells (lactate preferred fuel during heavy exercise) liver excreted through sweat some remains in blood

Aerobic Oxidation

involves oxygen ad proceeds completely to oxidative phosphorylation

What is the primary source of fuel by the heart during high intensity exercise?

lactate

The longer the duration, the greater the relative importance of the ___________ system compared to the phosphagen system

lactic acid

While speed and power are benefits of the anaerobic glycolysis metabolic process (lactic acid system), ____________ accumulates (negative effect)

lactic acid

Blood lactate levels reflect the balance between what?

lactic acid production and clearance

longer runs of 40-120 secs measures

lactic anaerobic power/capacity

Both oxygen deficit and EPOC are _________ during heavy or supramax exercise

large

What is the oxygen deficit likely due to?

limited cellular utilization of oxygen resulting from metabolic adjustments to anaerobic and aerobic systems

Acitivities requiring oxygen system (aerobic oxidation)

long distance 5,000 and 10,000 m run marathons cross country running soccer

energy system power

max amount of energy that can be produced per unit of time

Peak Power (PP)

max power exerted during very short duration (5 sec) work

Lactate clearance: 50-75% is due to __________. 10-25% is due to ____________. 5-10% is due to ___________.

oxidation gluconeogenesis/glyconeogenesis transamination

The aerobic oxidation metabolic process is known to produce the highest amount of __________ the body can consume during heavy dynamic exercise for the aerobic production of ATP

oxygen

Data used to calculate

peak power (PP) mean power (MP) fatigue index (FI)

Fatigue Index (FI)

percentage of PP drop-off during high-intensity, short duration work

Alternate names for alactic anaerobic metabolism

phosphagen or ATP-PC system

Rate of ATP production in anaerobic glycolysis (lactic acid system)

reaches its max after 5 seconds and is sustained for "several seconds"

Muscular fatigue

reduced force and velocity of muscle contraction - inhibition of actomyosin ATPase (enzyme responsible for the breakdown of ATP to provide the immediate energy for muscle contraction) - interference of hydrogen ions with the actions and uptake of calcium that is necessary for the excitation-contraction coupling and relaxation of cross-bridges

metabolic fatigue

results from a reduced production of ATP linked to enzyme changes, changes in membrane transport mechanisms, and changes in substrate availability - enzymes can be inactivated by hydrogen ions - membrane transport mechanisms affect movement of molecules across cell membrane and between cytoplasm and organelles (mitochondria) - energy substrate availability can be inhibited by a high concentration of hydrogen ions

Margaria-Kalaman Stair Climb What does it measure?

runs for 6 m on level, then up a staircase 3 steps at a time alactic anaerobic power measure (usually less than 5 secs)

At rest, generation from what three metabolic processes provide almost all needed energy

slow (aerobic) glycolysis - glucose Krebs Cycle ET-oxidative phosphorylation

Both oxygen deficit and EPOC are _________ during light to moderate submit exercise

small

Lactic Acid/Lactate Production is produced in muscle cells when.....

the NADH + H+ formed in glycolysis is oxidized to NAD+ by a transfer of the hydrogen ions to pyruvic acid

Oxygen Deficit

the difference between the oxygen required during exercise and the oxygen supplied and utilized - the discrepancy between supply and demand requires anaerobic sources to provide energy

Anaerobic threshold

the exercise intensity, usually described as a percentage of VO2max or absolute workload, above which blood lactate levels rise and minute ventilation increases disproportionately in relation to oxygen consumption - when the cardio system fails to supply the oxygen required to the muscle tissue

Maximal Lactate Steady State (MLSS)

the highest workload that can be maintained over time without a continual rise in blood lactate - it indicates an exercise intensity above which lactate production exceeds clearance

Energy system capacity

total amount of energy that can be produced by a system

The O2 system clearly dominates after ____ minutes

two