Transcript Blood Pressure and Heart Rate

Risk Factor Assessments
Chapter 3
What is Blood Pressure
• The force exerted by the blood on the walls
of the arteries (and veins) as the blood is
pumped around the circulation.
• Measured in units of mmHg.
• Most common methods of measuring BP is
by ascultation (listening for sounds).
Components of Blood Pressure
• Systolic pressure
– The highest pressure in the arteries due to the ejection of
blood from the heart into the aorta.
• Diastolic pressure
– The lowest pressure in the arteries occurring during the
relaxation phase of the heart
– Should measure both 4th and 5th phase.
• Pulse Pressure
– Difference in systolic and diastolic pressure; it is the
driving force that propels the blood in the arteries
Resting Blood Pressure
• Optimal
– Systolic is < 120 mmHg
– Diastolic is < 80 mmHg
• Hypertension
– Stage 1: 140-159/90-99
– Stage 2: ≥160/≥100
Exercise Blood Pressure
• Varies with age and gender
• Fitter individuals usually have lower exercise
blood pressure.
• Normal Response to incremental Exercise
– Systolic increases linearly until approaching
maximal at which time it begins to plateau.
Increases approx. 10-15 mmHg per Met, per 150 300 kgm.min-1, or per 25-50 watts.
– Diastolic does not significantly change.
Blood Pressure and Heart Rate Response to Exercise
200
200
SBP
180
180
4th Phase
5th Phase
160
160
140
140
120
120
100
100
80
80
60
60
40
40
20
20
0
0
Rest
50
75
100
Power Output (watts)
125
150
175
Heart Rate (bpm)
Blood Pressure (mmHg)
HR
Heart Rate
• Number of ventricular contractions per
minute
• Usually the same as pulse rate
Palpating Heart Rate
• Heart rates measured at a steady-state
(constant power output) should be measured
for as long as feasible up to 60 seconds.
Minimum time is 15 seconds.
• Heat rates measured after the exercise is
stopped but you want to know the HR during
the exercise should be measured for 6, 10 or
15 seconds, the shorter the better but must
maintain accuracy.
Resting Heart Rate
• Determined by genetics and fitness level
• Although lower resting HRs are not always
indicative of higher fitness when comparing
across individuals, the general pattern is that
more fit individuals have lower resting HRs.
• Within a healthy individual, a decrease in
resting HR is indicative if increased CV
fitness.
Exercise Hear Rate
• Heart rate increases linearly with increasing
power output until approaching maximum at
which time it begins to plateau.
• Amount of increase related to fitness
• CR fitness decreases submaximal HR at any
power output.
Maximal Heart Rate
• Maximal HR is primarily a function of age
• Fitness, gender, body mass do not affect
maximal HR.
• Estimation of Maximal HR
– Traditional equation: (220 – age)
– Best equation: [208-(0.7 x age)]
– SEE for predicting maximal HR is 10-12 bpm.
General Indications for Stopping an
Exercise Test in Low-Risk Adults
• Onset of angina-like symptoms
• A drop of 20 mmHg or more during steady-state
exercise in systolic BP or a failure of the SBP to rise
with an increase in exercise intensity
• Excessive rise in blood pressure:
– SBP > 260 mmHg
– DBP >115 mmHg
• Failure of HR to increase with increasing power
Power Output on the
Bicycle Ergometer
• Power = (Force X Distance)/ Time
• Force = kilograms of resistance applied
• Distance = distance the flywheel travels per
pedal revolution (6 meters)
• RPM = number of pedal revolutions per
minute
• Units of power = kgm.min-1
• Alternative is watts (1 watt = 6 kgm.min-1)