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 work-intensity 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 and natural killer cell activity at rest in young healthy females.