Heart Rate and VO2 Responses to Cycle Ergometry in White and African American Men

Abstract

The validity of estimates of peak oxygen consumption (VO2peak) using submaximal exercise tests may be compromised when the participants being tested are not similar to the participants used to develop the test. This study compared ethnic differences in the heart rate (HR) and oxygen consumption (VO2) responses to submaximal cycle ergometer exercise as well as measured and estimated VO2peak. Thirty-two men (White, n = 16; African American, n = 16) performed a graded maximal exercise test on a cycle ergometer. Submaximal HR and VO2 at 4 workloads (50, 100, 150, and 200 watts ), maximal HR, and measured peak VO2 values were evaluated for ethnic differences. Submaximal VO2 and HR values were used to estimate VO2peak based on the methods of the Astrand-Ryhming and Young Men's Christian Association (YMCA) submaximal exercise tests. White and African American men were matched for weight (87.6 ± 8.7, 85.5 ± 8.5 kg), body mass index (26.9 ± 2.4, 27.4 ± 2.5 kg/m2), VO2peak (3.56 ± 0.38, 3.40 ± 0.27 L/min), and maximal HR (185.8 ± 4.9, 186.7 ± 9.1), respectively. No ethnic differences were found in VO2 responses across the 4 workloads (p = .31). Heart rate responses to the 4 workloads were significantly lower (p < .0001) in the African American than in the White men. Estimated VO2peak values from the Astrand-Ryhming and YMCA protocols significantly (p < .0001) overestimated measured VO2peak in the African American men but not for the White men. We conclude that White and African American men of similar cardiovascular fitness level differ in HR responses to submaximal exercise during cycle ergometry. Caution should be exercised when using prediction tests to estimate maximal performance for members of ethnic groups not represented among the participants used to develop the prediction tests.