Difficulties in administering and evaluating a 3-minute step test modified for a clinical population.

Objective: Measurement of aerobic capacity is an important issue in clinical and research settings. We report on the design, use and attrition rate of a 3-minutes step test modified from the Queens College Step test that we hoped to use as an inexpensive and brief indicator of cardiovasular endurance.  Design:  We conducted a cohort survey and epidemiological study. Setting:  Two academic medical practices and three community clinics in Cleveland Ohio and Chicago Illinois. Participants:  Study population included a clinical sample of 1,234 White, Black, English-speaking and Spanish-speaking Hispanic adults aged 45-64. Methods: After two modifications of the Queens College Step test we used a 10 inch step height and a cadence of 23 steps per minute to represent our 3-minute step test. Subjects were stopped when they a) completed three minutes, b) when heart rates exceeded 80% of maximal predicted heart rate or reported nausea, dizziness or chest pain, or c) if they requested to stop.  Main Outcome Measurements: Main outcome measures were completion, dropout and stop rates.  Results: A total of 28% of subjects were able to complete the test, 36% had to be stopped when heart rates were excessive. The remainder either refused to attempt the test (13%) or requested to stop for symptoms of pain or fatigue (23%). Men and non-Hispanic whites were more likely to complete the test. Conclusion: Existing fixed cadence step tests that are ungraded are particularly problematic for assessing aerobic capacity/fitness in a clinical population because of high dropout rates during testing. Further exploration of self-paced tests should focus on the ability of subjects to complete the tests and the validity of those tests to predict aerobic capacity.