● Physical Fitness Testing
○ Instructions for GXT
■ Clients should refrain from ingesting good, alcohol, or caffeine or using
tobacco products within 3 hrs of testing
■ Clients should be rested
■ If the test is for diagnostic purposes, discontinue prescribed CV
medications WITH PHYSICIAN APPROVAL
● EKG or ECG
○ Same procedure to graphically record the conduction, magnitude, and duration of
the electrical current (potential) generated by the heart
● ♥
○ 4 chambers, 2 pumps
○ Conduction System
■ Sinoatrial node (SA node)
● Main pacemaker
○ Intrinsic or inherent rate is 60-100 bpm
● Located in right atrium
■ Atrioventricular node (AV node)
● Slows or delays in contraction/action of pump (~0.04-0.08 sec)
● Allows conduction wave to cross over intro ventricles
○ Purpose is so that the ♥ isn’t pumping all at the same time
● Located in the floor of right atrium
■ Bundle of His
● Intrinsic pace = ~60 bpm
● Divides impulse into L and R bundle branches (BB)
● Purpose is to push blood out
■ Purkinje Fibers
● Intrinsic rate = ~30-40 bpm
● Special neural tissue/muscle fiber network, conducts faster than
any cardiac area
● Without bundle of his, purkinje fibers could keep you alive through
polarization
■ Electrical conductivity
● ♥ beat originates in the part of the ♥ w the fastest beat (normally
the SA node of R atrium
○ Ectopic beats are those originating outside normal
pacemaker
● Atria electrically insulated from ventricles
● The ♥ has special electrical conducting tissue
○ Action potential
■ During depolarization
● Positive charge on the outside of the muscle, negative charge on
the inside
○ Positive charge due to sodium ions
■ Refractory period: once it’s depolarizing, it cannot depolarize for a
prolonged period of time
■ 5 phases (0-4)
○ Leads (bulk of the questions on the exam and quizzes)
■ 12 leads
■ Limb leads (I, II, III, & aVL, aVR, aVF)
■ 3 standard limb leads (I-III)
● Bipolar
■ 3 augmented limb leads (AVL, AVR, AVF)
● Unipolar
■ Limb leads give electrical views of the ♥ in the frontal plane
■ Chest leads (V1, V2, V3, V4, V5, V6)
● Chest leads give views of the ♥ in a transverse plane
○ Unipolar
■ V2 and V3 on the fourth intercostal, as flat as possible (avoid the
cleavage!)
■ V4, V5, V6 should be placed on the fifth intercostal, below the breast
tissue
● V5 at the midaxillary line (right below arm pit)
■ Placement
● 1st: V1 and V2
● 2nd: V4
● 3rd: V6
● THEN place the “in between” (V3 and V5)
● Finally, RA, LA, RL, LL
■ Einthoven’s Triangle
● All going from negative to positive
○ Limb Leads
■ Lead #1
● Right arm to left arm
■ Lead #2
● Right arm to left leg
■ Lead #3
● Left arm to left leg
■ aVR: center is positive, corner is negative
■ aVL: center is negative, corner is positive
■ aVF: center is negative, corner is positive
○ Chest Leads
■ “Each electrode is the positive pole for its
corresponding lead”
■ Negative electrode is in the center of the ♥ and
going outwards are all positive
○ EKG paper
■ 1 small box is 0.04 seconds — 1 mm
●
■ 1 large boxes row or column is 0.2 seconds (5 small boxes) — 5 mm
●
■ 2 large box row or column is 1 mV (10 small boxes)
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