Isometric thumb exertion induces B cell and T cell lymphocytosis in trained and untrained males: Physical aptitude determines response profiles

Purpose: The present study examined the effect of low-dose thumb exertion on lymphocyte subpopulation trafficking. The potential role of blood lactate in mediating lymphocyte redistribution was also investigated. Methods: 27 male participants (18 weightlifting-trained; 9 untrained) were separated into 3 groups of 9 (Weightlifting and Untrained Experimental: WL EXP , UT EXP ; Weightlifting Placebo: WL PLA ). WL EXP and UT EXP performed 4x60 second isometric thumb intervals separated by 60 second rest intervals in a single-blinded placebo-controlled study.  Participants were assessed over a 60 minute post-intervention recovery period for pain, blood lactate and lymphocyte subpopulation counts. Results: WL PLA did not change for any measured variable (pu003e0.05). The two experimentalgroups increased significantly (p 0.05). No differences in cell count were seen for CD56+/CD16+ lymphocytes across time for any group (pu003e0.05). UT EXP showed an early significant increase (20 min post-intervention) in CD4+CD3+ (20.78%, p 0.05). Conversely, WL EXP group showed no early increase followed by a delayed increase in cell count evident at the final time-point; CD4+CD3+ (19.06%, pu003c0.01), CD8+CD3+ (11.46%, p=0.033) and CD19+ (28.87%, pu003c0.01). Blood lactate was not correlated with lymphocyte counts. Conclusions: Physical aptitude and not cellular energy demand influences the lymphocyte response to resistance-exercise. Keywords: B-Lymphocytes; Exercise; Lactic Acid; Lymphocytosis; Resistance Training; T-Lymphocytes