Transcript Blood Pressure and Heart Rate

Blood Pressure and
Heart Rate
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 or
per 150 - 300 kgm.min-1.
– Diastolic does not significantly change.
Blood Pressure and Heart Rate Response to Exercise
200
200
SBP
180
4th Phase
180
160
5th Phase
160
140
120
120
100
100
80
80
60
60
40
40
20
20
0
0
Rest
150
300
450
Pow er Output (kgm .m in-1)
600
750
900
Heart Rate (bpm)
Blood Pressure (mmHg)
HR
140
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)