Exercise Physiology Essay, Research Paper

Introduction:

This study assessed heart rate, blood pressure, and pulse oximeter readings at rest and during exercise. The heart rate (HR), blood pressure (BP), and oximetery measurements provide better insight into the inner workings of the human body. In using the results of the assessment, one can determine the affects that rest and exercise have on the cardiac system.

Heart rate is described as the rate of the cardiac cycle. Heart rate is measured in beats per minute (bpm). A well conditioned heart is able to pump large amounts of blood with each beat. This is called bradycardia (* 60 bpm). In contrast, a poorly conditioned heart is called tachycardia (* 100). Males have an average resting heart rate between 60-70 bpm, whereas females average between 70-80 bpm. In addition, resting heart rate can be affected by many variables. These include one’s body position, consumption of alcohol or drugs, and fatigue.

Blood pressure is defined as an outward force that distends blood vessel walls, “dependent on the energy of the heart action, elasticity of the arterial walls and volume and viscosity of the blood” (Dorland’s 1995). The standard unit of expressing blood pressure is in millimeters of mercury (mmHg). While testing, there are different sounds or phases heard when using a stethoscope to find blood pressure. These sounds define the measurable blood pressure. The first sound is the systolic BP, which indicates the pressure against the brachial artery as the heart contracts. The last sound heard relates to the diastolic BP, which is the pressure exerted when the heart is relaxed. When recording the BP, the systolic is over the diastolic BP (systolic/diastolic). Measuring resting blood pressure is used to screen for hypertension and also hypotension. It is also used to evaluate influences of medications on the cardiovascular system. The average resting blood pressure is around 120/80 mmHg.

The pulse oximeter is a photoelectric device for determining the oxygen saturation of the blood using the left index finger. In other words, “the machine senses the levels of saturated hemoglobin and will convert that amount to a percent of saturation” (Bilsky 2000). At rest, the normal oximetry reading is 97%. However, because Greeley is above sea level (around 5,000 ft.), the assessment will base the normal measurement at 95%.

Exercise heart rate is used to help an individual utilize a specific energy system and/or condition specific systems of the body. One can utilize exercise to stimulate the heart rate. This is done by walking up and down stairs at different intensities. The rate of the cardiac cycle is a valid indicator of demands that are required on one’s body. During exercise, BP is indirectly indicated by intensity or exertion levels. The systolic BP is expected to rise because of the increase in cardiac output. Diastolic BP is expected to remain equivalent to resting levels or decrease during exercise indicating an increase of vasodilation and an opening of the capillary beds. Furthermore, the pulse oximeter reading should stay relatively the same from rest to exercise, at approximately 97% (Fox 1999).

It is essential to have a basic understanding of heart rate, blood pressure, and pulse oximetry readings in order to assess a person’s cardiovascular functioning. If the subject’s HR, BP, and pulse oximetry readings are all functioning normally, then his HR and BP will increase with increased physical exertion and his pulse oximetry reading will stay relatively constant.

Methods:

To perform the exercise assessment, the administers applied the use of a blood pressure cuff and stethoscope (for measuring BP), a metronome (to set step rate), a heart rate monitor (accurately measuring HR), and an area with two flights of stairs. The HR monitor and BP cuff were attached to the subject. The participant carried the metronome in order to accurately hear and perform the specified step rate produced.

Prior to exercise, measurements of heart rate, blood pressure, and pulse oximetry were taken at rest. According to the designed protocol, the metronome was set to a beginning specified rate (96 steps/min). The assessment time started and the subject began to walk down the two flights of stairs. The subject stepped to the rate given by the metronome, which increased in intensity/speed every two minutes (120 steps/min after 2 min. and 160 steps/min after 4 min.). The assessment period continued for six minutes, in which heart rate was measured throughout every thirty seconds.

During the post-exercise/recovery period (a total of three minutes), HR was further recorded every thirty seconds and BP was measured at the beginning of the recovery period (at 6.5 min.).

Post-recovery measurements were taken to confirm the subject’s full recovery (6 min. post-exercise). These measurements include HR, BP, and pulse oximetry.

Results:

Pre-exercise: Resting HR: 62 bpm

Resting BP: 120/70 mmHg

Pulse Oximetry: 95%

Exercise/Recovery: (Table 1.1)

Time (min.) Intensity (steps/min.) Heart Rate (bpm) Blood Pressure (mmHg)

0.5 96 93

1.0 96 107

1.5 96 106

2.0 96 108

2.5 120 112

3.0 120 120

3.5 120 129

4.0 120 130

4.5 160 141

5.0 160 157

5.5 160 163

6.0 160 167

6.5 0 158 140/75

7.0 0 146

7.5 0 120

8.0 0 104

8.5 0 111

9.0 0 101

Post-exercise (6 min post-exercise):

HR: 66 bpm

BP: 120/70 mmHg

Pulse Oximetry: 98%

Discussion:

Exercise assessments have many indications. These include assessing “functional class and response to therapy for heart failure” (Willenheimer 2000), assessing hypo/hyper-tension, assessing VO2 Max (maximal oxygen uptake), and an overall physical fitness. Poor physical fitness is associated with an impairment of cardiac function during exercise (Tulppo 1998).

The results show the effects rest and exercise have on the cardiovascular system, through HR, BP, and pulse oximetry measurements. The subjects results were indicative of normal cardiac function. At rest, the subject had HR and BP measurements within the average range for both sex and age (HR 62 bpm, BP 120/70 mmHg). Also at rest, the pulse oximetry reading indicated normal oxygen saturation of hemoglobin (95% saturation).

As seen in table 1.1 in the results, the subjects HR increased simultaneously with an increase in exercise intensity. BP increased along with exercise intensity and duration. In addition, pulse oximetry slightly rose with exercise, but stayed within the normal range (98% saturation).

In terms of recovery, it took approximately six minutes post- exercise for the subject’s HR and BP to return relatively to his normal resting cardiac state (HR 66 bpm, BP 120/70 mmHg).

Overall, the subject showed signs of having a healthy, well functioning, cardiovascular system. However, there were some variable factors present that may have influenced the results of the assessment. In terms of HR, it is influenced by body position, diet, consumption of drug, alcohol, and/or caffeine, and any level of fatigue. Also, the lowering of stroke volume from dehydration is related to an increase in HR (Gonzalez 2000). The assessors used a HR monitor to get a more exact measurement of the subject’s HR. BP readings can be affected by; the previously stated affecters of HR (caffeine intake, etc.), a lack of experience or ignorance of the assessor, and/or inaccurate equipment.

In this assessment, the modified protocol prohibited the evaluators from measuring BP and pulse oximetry consistently throughout the exercise time. A bike or treadmill would be much easier for the assessors to measure BP at consistent intervals. This study was important in learning the affects of exercise on HR, BP, and pulse oximetry, and would have been more accurate and useful if the evaluators had access to a wider range of equipment/facilities.

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