Physical Training Augments Plasma Catecholamines and Natural Killer Cell Activity

To elucidate the effects of a 10-week exercise training period on physical fitness and plasma catecholamine concentration at rest, and on natural killer cell activity in young healthy untrained females, subjects (20―22 years old. N＝16) carried out physical training by a protocol which consisted of treadmill jogging at a workintensity of 50% of their VO2max two hours a day three times a week for ten weeks. VO2max was increased significantly from 33.1±3.4 ml/kg/min to 38.3±6.6 ml/kg/min by the ten weeks of physical training (P＜0.005), and natural killer cell activity was also increased significantly from 31.9±14.3% to 46.4±18.4% (P＜0.05). The concentrations of epinephrine and norepinephrine before and after physical training were 18.3±8.7 pg/ml and 20.4±8.9 pg/ml, and 134.1±52.2 pg/ml and 248.1±106.8 pg/ml (P＜0.005), respectively. Changes in norepinephrine and epinephrine correlated with the change in VO2max (r＝0.780, P＜0.005; r＝0.556, P＜0.05). While the change in natural killer cell activity correlated with the change in epinephrine (r＝0.623, P＜0.01), the correlation of the change in natural killer cell activity with change in norepinephrine did not reach statistical significance (r＝0.497, P＝0.0503). From these results we concluded that physical training augments plasma catecholamine levels natural killer cell activity at rest in young healthy females.