Rationale:
The six-minute cycle (6MC) test is a commonly used assessment of physical performance in North Carolina cardiac rehabilitation (CR) participants. This test was designed as an alternative for CR facilities with limitations that did not allow for appropriate administration of the six-minute walk (6MW) test. However, to date this test has not been analyzed for reliability or for validity when compared to a maximal graded exercise (MGX) test.
Objective:
To investigate the relationships between 6MC tests performed over 3 time periods and how these tests compared to 6MW and MGX tests in entry-level CR participants.
Methodology:
Eighty men and 21 women (N = 101) with cardiovascular disease aged 42-79 years who entered the CR program at NorthEast Medical Center performed 6MC tests on a Schwinn AirDyne(TM) cycle ergometer at the same time of day for 3 consecutive visits to the center within the first week of CR participation. Distance pedaled was calculated to the nearest 1/100 of a mile and converted to feet. These same participants performed a 6MW test on their first CR visit and a MGX test using a Modified Bruce protocol prior to their first CR visit. Treadmill performance was measured by time and then converted to maximal metabolic equivalents (MET) values using ACSM prediction equations. Resting and peak exercise heart rate, blood pressure, and Borg rating of perceived exertion (6-20 scale) were also measured during each test.
Results:
Pearson correlation coefficients ranged from 0.78 to 0.89 for the three 6MC tests, showing good test-retest reliability. Correlations between the 6MC, 6MW, and MGX tests are shown below:
Conclusions:
The third 6MC trial and 6MW test showed the greatest relationship to the MGX test, indicating that a 6MC testing effect may have been evident. Based on this patient cohort, the 6MC test appears to be both a reliable and valid measure of functional capacity in CR entry participants.