Oxygen uptake and heart rate relationship in persons with spinal cord injury

Abstract

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 = 1.3x-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.(ABSTRACT TRUNCATED AT 250 WORDS)