Catecholamine response to exercise in individuals with different levels of paraplegia

The purpose of this study was to investigate the effect of the level of injury on the serum level of norepinephrine (Nor) and epinephrine (Epi) at rest and after maximal exercise in individuals with paraplegia. Twenty-six male spinal cord-injured subjects with complete paraplegia for at least 9 months were divided into two groups of 13 subjects each according to the level of injury, i.e., T1-T6 and T7-T12. Serum Nor and Epi concentrations were measured by HPLC-ECD, at rest (PRE) and immediately after a maximal ergospirometric test (POST). Statistical analysis was performed using parametric and non-parametric tests. Maximal heart rate, peak oxygen uptake, and PRE and POST Nor were lower in the T1-T6 than in the T7-T12 group (166 +/- 28 vs 188 +/- 10 bpm; 18.0 +/- 6.0 vs 25.8 +/- 4.1 ml kg(-1) min(-1); 0.54 +/- 0.26 vs 0.99 +/- 0.47 nM; 1.48 +/- 1. 65 vs 3.07 +/- 1.44 nM). Both groups presented a significant increase in Nor level after exercise, while only the T7-T12 group showed a significant increase in Epi after exercise (T1-T6: 0.98 +/- 0.72 vs 1.11 +/- 1.19 nM; T7-T12: 1.24 +/- 1.02 vs 1.89 +/- 1.57 nM). These data show that individuals with paraplegia above T6 have an attentuated catecholamine release at rest and response to exercise as compared to subjects with injuries below T6, which might prevent a better exercise performance in the former group.