OXYGEN-UPTAKE AND HEART-RATE RELATIONSHIP IN PERSONS WITH SPINAL-CORD INJURY

The percent (%) peak oxygen uptake (VO2) and %peak heart rate (HR) relationships were determined in 13 persons with high (T1-T6) and 14 persons with low lesion (T7-T12) spinal cord injured paraplegia (SCI PARA) and 15 nonimpaired subjects during graded arm crank (AC) tests to exhaustion. Subjects were instructed to maintain a target cadence of 60 rpm on a modified electronically braked leg cycle ergometer. After 3 min of unloaded cranking, power output (PO) was increased by 8-16 W.min-1. VO2 and HR were determined via open-circuit spirometry and 12-lead ECG, respectively. Absolute HR and VO2 values for each PO were converted to %peak HR and %peak VO2 values. Linear regression slopes describing individual %peak HR and %peak VO2 relationships were calculated and compared between groups with one-way ANOVA. No significant differences (P > 0.05) were noted between the mean (+/- SD) regression slopes for persons with high lesion SCI PARA (1.48 +/- 0.21), persons with low lesion SCI PARA (1.48 +/- 0.26), and nonimpaired subjects (1.53 +/- 0.29). Regression equations derived using all data points within each group were as follows: High lesion SCI PARA: y = 1.31x - 37.0, R = 0.85 Low lesion SCI PARA: y = 1.23x - 30.9, R = 0.88 Nonimpaired subjects: y = 1.41x - 46.2, R = 0.95 (y = %peak VO2, X = %peak HR). These equations are similar to those previously reported for nonimpaired men and women and cardiac patients during AC and leg cycle ergometry. Therefore, the data suggest that already established exercise prescription guidelines need not be modified for persons with high or low lesion SCI PARA and HR can be confidently used as an indicator of AC exercise intensity in these persons.