Lymphocyte proliferation in response to acute heavy resistance exercise inwomen: influence of muscle strength and total work

Little is understood about the immune responses to heavy resistance exercis e. The purpose of this investigation was to determine the influence of phys ical strength and the ability to do more total work on lymphocyte prolifera tion after an acute bout of heavy resistance exercise. A group of 50 health y but nonstrength trained women were recruited for the study and tested for their one repetition maximum (i.e. 1 RM or maximal mass lifted once). From the normal distribution of strength the top and bottom 8 women [mean age 2 2.5 (SD 3.1) years] were asked to volunteer to define our two groups (i.e. high strength and low strength). The two groups were significantly differen t (P < 0.05) in 1 RM squat strength [low strength 39.9 (SD 4.6) kg, 0.65 (S D 0.08) kg.kg body mass(-1) and high strength 72.2 (SD 10.7) kg, 1.1 (SD 0. 12) kg.kg body mass(-1)] but were not significantly different in body mass, age, activity levels, and menstrual status (all in same phase). Each perfo rmed a resistance exercise protocol consisting of six sets of 10 RM squats with 2 min rest between the sets. The 10 RM loads and total work were signi ficantly greater in the high strength group than in the low strength group. Blood samples were obtained pre-exercise and immediately post-exercise for test for lactate (significant increase with exercise) and cortisol (no cha nges) concentrations with no differences noted between groups. Immunologica l assays on the blood samples determined the incorporation of tritiated thy midine by lymphocytes in responses to concanavalin A (ConA), phytohemagglut inin (PHA), and pokeweed mitogen (PWM). Following the squat exercise, there was a significant decrease in lymphocyte responsiveness to PWM in the high strength but not in the low strength group for both total proliferation an d proliferation adjusted per B or T cell. On the other hand, lymphocytes fr om the low strength group proliferated to a significantly greater extent (a djusted per T cell) in response to ConA and PHA. These data indicate that t he heavy resistance exercise protocol reduced the lymphocyte proliferative responses only in the stronger group of subjects. This effect may have been due to the high absolute total work and the greater exercise stress create d by the resistance exercise protocol in the high strength group. Therefore , individuals performing at the same relative exercise intensity (i.e. 10 R M) in a resistance exercise protocol may have different immune responses st emming from differences in absolute total work performance.