[Effects of resistance training on physical fitness, muscle strength, and natural killer cell activity in female university students].

OBJECTIVES The health benefits of resistance training for women have been well documented. However, few investigations have been reported on the immune responses to resistance training among young people. To determine the effects of resistance training on natural killer cell activity (NKCA) in young people, a study was conducted among healthy female university students. METHODS The study was conducted with 22 healthy non athlete female university students (aged 19.8+/-1.3 years) who volunteered to participate in the study. Six women were assigned to exercise group (a) that carried out resistance training five or six times a week, another six women were assigned to exercise group (b) that carried out resistance training three or four times a week, and the remaining ten comprised, the control group (non exercise group). The exercise groups carried out resistance training for both the upper and lower parts of the body using ankle and wrist weights for 8 weeks. Blood samples were obtained at the onset of the study (before the start of any activity in the exercise groups) and at the conclusion of the training (8 weeks later) in order to determine NKCA. A physical fitness test and a muscle strength test were conducted on the subjects to assess the strength of the upper and lower parts of the body, muscular endurance, and flexibility. RESULTS The mean NKCA at the conclusion of the training showed a significant increase in exercise group (b), even though there was no significant difference in NKCA in the non exercise group or in exercise group (a) between before and after the training. An improvement in physical fitness and muscle strength was observed in exercise group (a) and exercise group (b). CONCLUSIONS This study showed that resistance training improved physical fitness, muscle strength, and NKCA in young female subjects. Regarding the effects of exercise frequency on NKCA, this study suggests that exercise carried out three of four times a week might be associated with an increase in NKCA.