Exercise Physiology Exam 2 (KIN 4100)

Lactate threshold

Point at which blood lactate accumulation increases markedly

• blood lactate accumulates significantly,% of V02 max

Anaerobic Energy Expenditure

O2 demand > O2 consumed in early exercise

• body enters O2 deficit

• occurs when anaerobic pathways are used for ATP production

Post exercise O2 consumption

O2 consumed > O2 demand in early demand

• excess post exercise O2 consumption (EPOC)

• replenishes ATP/PCr stores, converts lactate to glycogen, clears CO2, replenishes hemo/myoglobin, clears CO2

VO2 max

• point at which O2 consumption no longer increases (hit Vo2 max)

• single best predictor of aerobic fitness

• training allows athletes to compete at higher levels of VO2 max

• Absolute: L/min

• Relative: mL/kg/min

EPOC

• Excess Postexercise Oxygen Consumption

• replenishes ATP/PCr stores, converts lactate to glycogen, clears CO2, replenishes hemo/myoglobin, clears CO2

What are the 2 definitions of fatigue

• decrements in muscular performance with continued effort, accompanied by sensations of tiredness

• inability to maintain required power output to continue muscular work at given intensity

What is fatigue reversible by

Rest

What are the sites of central fatigue

Central Nervous System (CNS)

• brain

• spinal cord

• neuron

What are the sites of peripheral fatigue

Peripheral Nervous System

Skeletal Muscle Fibers

What are some of the causes of Fatigue (energy systems and glycogen depletion)

• glycogen reserves: limited and get depleted quickly

• deleted more quickly with high intensity exercise or first few minutes of exercise*

• Depletion is correlated with fatigue

  • related to total glycogen depletion but unrelated to rate of glycogen depletion

Fiber type and recruitment patterns

• fibers recruited first get depleted faster

• type I fibers get depleted after mod endurance exercise

Recruitment dependent on exercise intensity (muscle fibers)

Type I: recruited first (light/mod intensity)

Type IIa: recruited next (mod/high intensity)

Type IIx: recruited last (max intensity)

Functions of the Cardiovascular System

1. deliver blood and nutrients, remover CO2 and waste

2. Transport hormones and aid in immune function

3. help maintain temperature, fluid, and acid-base homeostasis

Pulmonary Circulation (right heart)

Superior/Inferior vena cava → RA→ tricuspid valve → RV→pulmonary valve→pulmonary arteries → lungs

Systemic Circulation (left heart)

lungs → pulmonary veins → LA → mitral valve (bicuspid valve) → LV → aortic valve → aorta

What is the spontaneous rhythmicity of the heart?

100 bpm

SA node

• pacemaker cells

• cause contraction in RA and LA

AV node

• found in the RA wall near heart center

• delays signal so atria can contract before ventricles

• relays to bundles after delay

AV bundle (bundle of his)

• sends signal down to apex of heart

• divides into left and right branches

Purkinje fibers

Stimulate ventricular contraction

Parasympathetic Nervous System

• Reaches heart by vagus nerve and releases ACh

• Decreases HR to RHR of 60-100

Sympathetic Nervous System

• Releases norepinephrine

• Increases HR up to 250 bpm

Diastole (relaxation phase)

2x as long as systole (contraction phase)

Ventricular Systole

• QRS complex to T wave 1/3 of total cycle

• Mitral and Tricuspid valves close (lub) semilunar valves open and blood is ejected

• End systolic volume (ESV) - blood remaining in ventricles after systole

Ventricular Diastole

• T wave to next QRS complex 2/3 of total cycle

• Semilunar valves close (dub), Av valves open

• End Diastolic Volume (EDV) blood in ventricles after atrial contraction

Stroke Volume (SV)

EDV-ESV

Ejection Fraction

SV / EDV

Cardiac Output (Q)

Q (L/min) = SV (mL/beat) x HR (bpm)

• volume of blood pumped per minute

• resting output 4.2-5.6 L/min and increases rapidly during rest to exercise transition (up to 25 L/min)

Cardiac Drift

A decrease in SV caused by decreased plasma volume, which causes Increased HR

Mean Arterial Pressure (MAP)

2/3 DBP + 1/3 SBP

Blood plasma

55-60 % of total volume

Can ± 10% due to dehydration, training

Formed elements (in blood and vessels)

40-45% total volume

Hematocrit =% of volume made up of formed elements

How many of each do you find in blood Hematocrit?

• RBC: 99%

• White blood cells -<1%

• Platelets -<1%

Metabolic Mechanisms (VD intrinsic)

Buildup of metabolic products, CO2, and decreased O2

Endothelial mechanisms (VD, intrinsic)

Substances secreted by vascular endothelium (NO prostaglandins, ect)

Myogenic mechanisms (VD intrinsic)

Local pressure causes VD or VC

Neural control (extrinsic)

Sympathetic causes systemic VC and heart VD

At rest how much blood directs itself to the muscles and how much goes to the liver and kidneys?

Heart: 20%

Liver and Kidneys: 50%

During exercise how much blood goes to the muscles

>80% of bloodflow

What are the cardiovascular factors the increase stroke volume

1. increased preload

2. increased contractility

3. decreased afterload

Anticipatory response

HR increases above resting HR just before start of exercise

Steady state HR

point of plateau, optimal HR for meeting demands at given submax intensity

if intensity increases so does steady state HR

Stroke Volume (SV)

Increases with intensity to 40-60% VO2 max

plateaus beyond this except for elite endurance athletes

Hemoconcentration

Decrease plasma volume, increase hematocrit=increase in RBC concentration

Higher O2 carrying capacity (not always good)

What does the SAID principle stand for?

Specific Adaptations to Imposed Demands

Is inspiration active or passive

Active

Volume of blood pumped per beat per minute

cardiac output

What are the 3 major circulatory components of the cardiovascular system?

1. the heart (pump)

2. blood vessels

3. fluid medium (blood)

What is happening during QRS complex of an ECG

Ventricular depolarization

Inspiration

active process: expansion of chest cavity and lungs and a decrease in pressure in lungs

muscles used

Rest: diaphram and external intercostals

Exercise: scalenes, sternocleidomastoid, pectorals

Expiration

passive process at rest

muscles used

rest: non because it is a passive process

Exercise: internal intercostals, lats, quadratus lumborum, abs

Atmospheric pressure

760 mmHG