Faculty Advisor Name
Dr. Trent A. Hargens
Description
- Overview of the Project
The project being presented investigated the reliability of a hemodynamic device. Subjects were asked to perform two running tests and two treadmill tests while wearing a device known as the PhysioFlow. The device is based off Ohm’s Law and runs a high frequency, low magnitude electric current through the individual’s thoracic region. The current is absorbed as the heart beats to determine the amount of blood the individual’s heart ejects per beat.
The present study investigated the hemodynamic differences across running and cycle exercise. To determine this, the subject ran/walked at two given intensities, during which oxygen consumption was directly measured using a metabolic cart. From the oxygen values obtained from walking/running, intensities for cycling were matched.
Subjects
The present study recruited twenty-one (10) male subjects, who were all apparently healthy with no previous diagnosis of cardiovascular, pulmonary, or metabolic disease.
Pre-test
Subjects were asked to visit JMU’s Human Performance Lab on four separate occasions for approximately 1 hour each visit. Subjects were fasted and abstained from caffeine and alcohol four hours prior to testing. Following the completion of informed consent, subjects were given two questionnaires to complete: the Physical Activity Readiness Questionnaire (PARQ) and the International Physical Activity Questionnaire, Short Form (IPAQ). Subject height and weight were recorded to the nearest 0.5cm and 0.1Kg, respectively.
Hemodynamic Measures
Hemodynamic measures of cardiac output, heart rate, stroke volume, contractility index, ventricular ejection time, early diastolic filling ratio, left cardiac work index, systemic vascular resistance, end diastolic volume, and ejection fraction were measured through the PhysioFlow (PF07 Enduro, Manatec Biomedical; Paris, France). Six electrodes were used for this device: two electrodes placed above the supraclavicular fossa, two placed just left of the spine dorsally in line with the xiphoid processes, and two ECG electrodes (V1 and V6) to determine heart rate. The PhysioFlow recorded hemodynamic measures in 10 second averages at rest and throughout the exercise test described below in addition to a 3-minute recovery period.
Exercise Tests
Subjects performed a total of four graded exercise tests, two on the treadmill (GE CASE) and two on an electronically braked cycle ergometer (Ergoline VIAsprint 150P) (TM1, TM2, CYC1, and CYC2). Oxygen consumption was measured through indirect calorimetry via metabolic cart (Parvo Medics; Sandy, UT). TM1 was designated as the first visit while the final three tests were conducted in a randomized order. All four tests were completed with a minimum of 48 hours between tests and occurred at the same time of day. The custom treadmill protocol was established as follows: 2.6mph @ 0% (1min), 3.1mph @ 1.5% (1min), 3.6mph @ 2.5% (5 min), 4mph @ 3.5% (1 min), 4mph @ 5.5% (5min), 5mph @ 1% (1min), 5.3mph @ 2.5% (1min), 5.6mph @ 5% (1min), 6.1mph @ 6.5% (1min), 6mph @ 10.5% (1min), 6mph @ 14% (1min), 6mph @ 16.5%, 6.2mph @ 17.5%, and 6.4mph @ 18.5% (if reached, until exhaustion).
The cycling test protocol was matched at the same oxygen consumption levels for the two 5-minute stages. Watts for the given METs will be estimated using the metabolic equations (American College of Sports Medicine, 2013).
Testing ceased at volitional exhaustion, an inability to maintain 60 revolutions per minute on the cycle ergometer, or if the subject reported any adverse effects as outlined in the ACSM Guidelines (American College of Sports Medicine, 2013). The two 5-minute stages (Stage 1 and Stage 2) were designed to ensure steady-state at 5 and 7 METs, which correspond to moderate and vigorous intensity respectively (American College of Sports Medicine, 2013). Blood pressure was measured 3 minutes into Stages 1 and 2. All values recorded in final 2 minutes of Stage 1 and Stage 2 were averaged together to examine the PhysioFlow’s test re-test reliability.
Abstract
Included in
Reliability of Impedance Cardiography in the Measurement of Cardiovascular Hemodynamics during Exercise.
- Overview of the Project
The project being presented investigated the reliability of a hemodynamic device. Subjects were asked to perform two running tests and two treadmill tests while wearing a device known as the PhysioFlow. The device is based off Ohm’s Law and runs a high frequency, low magnitude electric current through the individual’s thoracic region. The current is absorbed as the heart beats to determine the amount of blood the individual’s heart ejects per beat.
The present study investigated the hemodynamic differences across running and cycle exercise. To determine this, the subject ran/walked at two given intensities, during which oxygen consumption was directly measured using a metabolic cart. From the oxygen values obtained from walking/running, intensities for cycling were matched.
Subjects
The present study recruited twenty-one (10) male subjects, who were all apparently healthy with no previous diagnosis of cardiovascular, pulmonary, or metabolic disease.
Pre-test
Subjects were asked to visit JMU’s Human Performance Lab on four separate occasions for approximately 1 hour each visit. Subjects were fasted and abstained from caffeine and alcohol four hours prior to testing. Following the completion of informed consent, subjects were given two questionnaires to complete: the Physical Activity Readiness Questionnaire (PARQ) and the International Physical Activity Questionnaire, Short Form (IPAQ). Subject height and weight were recorded to the nearest 0.5cm and 0.1Kg, respectively.
Hemodynamic Measures
Hemodynamic measures of cardiac output, heart rate, stroke volume, contractility index, ventricular ejection time, early diastolic filling ratio, left cardiac work index, systemic vascular resistance, end diastolic volume, and ejection fraction were measured through the PhysioFlow (PF07 Enduro, Manatec Biomedical; Paris, France). Six electrodes were used for this device: two electrodes placed above the supraclavicular fossa, two placed just left of the spine dorsally in line with the xiphoid processes, and two ECG electrodes (V1 and V6) to determine heart rate. The PhysioFlow recorded hemodynamic measures in 10 second averages at rest and throughout the exercise test described below in addition to a 3-minute recovery period.
Exercise Tests
Subjects performed a total of four graded exercise tests, two on the treadmill (GE CASE) and two on an electronically braked cycle ergometer (Ergoline VIAsprint 150P) (TM1, TM2, CYC1, and CYC2). Oxygen consumption was measured through indirect calorimetry via metabolic cart (Parvo Medics; Sandy, UT). TM1 was designated as the first visit while the final three tests were conducted in a randomized order. All four tests were completed with a minimum of 48 hours between tests and occurred at the same time of day. The custom treadmill protocol was established as follows: 2.6mph @ 0% (1min), 3.1mph @ 1.5% (1min), 3.6mph @ 2.5% (5 min), 4mph @ 3.5% (1 min), 4mph @ 5.5% (5min), 5mph @ 1% (1min), 5.3mph @ 2.5% (1min), 5.6mph @ 5% (1min), 6.1mph @ 6.5% (1min), 6mph @ 10.5% (1min), 6mph @ 14% (1min), 6mph @ 16.5%, 6.2mph @ 17.5%, and 6.4mph @ 18.5% (if reached, until exhaustion).
The cycling test protocol was matched at the same oxygen consumption levels for the two 5-minute stages. Watts for the given METs will be estimated using the metabolic equations (American College of Sports Medicine, 2013).
Testing ceased at volitional exhaustion, an inability to maintain 60 revolutions per minute on the cycle ergometer, or if the subject reported any adverse effects as outlined in the ACSM Guidelines (American College of Sports Medicine, 2013). The two 5-minute stages (Stage 1 and Stage 2) were designed to ensure steady-state at 5 and 7 METs, which correspond to moderate and vigorous intensity respectively (American College of Sports Medicine, 2013). Blood pressure was measured 3 minutes into Stages 1 and 2. All values recorded in final 2 minutes of Stage 1 and Stage 2 were averaged together to examine the PhysioFlow’s test re-test reliability.
