Catecholamine response to exercise in individuals with different levels ofparaplegia

The purpose of this study was to investigate the effect of the level of inj ury on the serum level of norepinephrine (Nor) and epinephrine (Epi) at res t and after maximal exercise in individuals with paraplegia. Twenty-six mal e spinal cord-injured subjects with complete paraplegia for at least 9 mont hs 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 me asured by HPLC-ECD, at rest (PRE) and immediately after a maximal ergospiro metric 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 18 8 +/- 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 prese nted 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). T hese data show that individuals with paraplegia above T6 have an attentuate d catecholamine release at rest and response to exercise as compared to sub jects with injuries below T6, which might prevent a better exercise perform ance in the former group.