Background: This study was designed to examine the relationship between endurance training volume and natural killer cell (NK) cytolytic activity. We hypothesized that a dose dependent relationship exists between forced treadmill training volume and training induced increases in NK cell cytolytic activity.
Experimental design: female, Swiss Webster mice were assigned to treadmill control (TC) or treadmill trained groups (n = 10 per group). Trained mice ran at 12 m per min. (8 degrees grade) for: 15 (EX15), 30 (EX30), or 60 minutes (EX60) per day, five days per week for 11 weeks. Splenic NK cell activity was expressed as median lytic unit (LU), median LU per asialo GM1 (AsGM1+) cell, and median LU per spleen.
Results: Median NK activity was not significantly increased by training volume. A trend toward greater median LU per AsGM1+ cell was observed in EX30 group versus TC (p = 0.1). Training volumes less than or greater than this level produced smaller increases in NK cytolytic activity.
Conclusions: These data provide preliminary evidence indicating that training induced increases in splenic NK cell cytolytic activity do not exhibit a dose dependent relationship with treadmill training volume.