EFFECT OF ECCENTRIC EXERCISE ON NATURAL-KILLER-CELL ACTIVITY

The effect of eccentric one-legged exercise on natural killer (NK) cel l activity was studied in eight healthy males. To distinguish between local and systemic effects, blood samples were collected from veins in the exercising leg and resting arm. However, the results did not sign ificantly differ between the leg and arm. To eliminate diurnal variati ons, the results were c:ompared with a control group that did not exer cise but had blood samples collected at the same time points. In the e xercising group, plasma creatine kinase increased progressively during and up to 4 days after exercise. The percentage of CD16(+) NK cells i ncreased during exercise, which was paralleled by an increase in the N K cell activity per fixed number of blood mononuclear cells. The NK ce ll activity on a per NK cell basis did not change. The percentage of C D3(+), CD4(+), CD8(+), CD19(+), and CD14(+) cells did not change signi ficantly during exercise. The present study thus showed that eccentric exercise viith a relatively small muscle mass (1 quadriceps femoris m uscle) causes systemic effects on NK cells. It is suggested that the i ncrease in plasma epinephrine during eccentric exercise is responsible for the observed increase in the percentage of CD16(+) cells.