T-cell responses to acute cardiorespiratory or resistance exercise in cohorts of physically active or physically inactive older adults: A randomized complete crossover

Aging is associated with many chronic diseases that are maintained and perpetuated by immune dysregulation and chronic systemic inflammation. T-cells often undergo age-related changes, including an accumulation of memory cells, which places individuals at increased risk for novel infections and may predispose them to increased inflammation. Regular exercise training has been suggested to offset age-related changes in T-cells, but the majority of literature is derived from cardiorespiratory exercise (CRE) studies. Much less is understood about the T-cell response to resistance exercise (RE). The purpose of this study was to examine the effects of acute CRE and acute RE on the T-cell response among a cohort of physically active older adults (PA) compared to a cohort of physically inactive older adults (PI). METHODSTwenty-four healthy older adults (PA n=12; PI n=12; mean {+/-} SD; age (yrs) PA 62 {+/-} 5, PI 64 {+/-} 5; height (cm) PA 170.9 {+/-} 6.9, PI 162.9 {+/-} 8.0; weight (kg) PA 69.3 {+/-} 10.2, PI 68.2 {+/-} 12.8; BMI (kg/m2) PA 23.9 {+/-} 3.0, PI 25.6 {+/-} 3.5) completed one bout of CRE and one bout of RE in a randomized order, both at a moderate intensity, and separated by at least 7 days. Blood samples drawn pre-exercise, post-exercise, and 1h post-exercise (recovery) were analyzed for CD4+ and CD8+ T-cells and their differentiation status using surface markers CD45RA, CD62L, and CD57, as well as for Th17 cells (CD4+ CD161+ CD196+) using flow cytometry. RESULTSPI had higher numbers of circulating CD57+ EMRA CD4+ T-cells (PA, mean {+/-} SE, 1 {+/-} 2 cells/uL; PI, 6 {+/-} 2 cells/uL; p=0.01; z=2.32) than PA at pre-exercise. Both CRE and RE elicited a significant mobilization of highly-differentiated (CD45RA+ CD62L-; CD57+ CD45RA+ CD62L-) CD8+ T-cells into the circulation post-exercise in both PA and PI groups. Furthermore, CRE resulted in a decrease in the number of circulating Th17 cells post-exercise, while RE increased Th17 cell mobilization compared to the CRE response. CONCLUSIONTaken together, T-cells in PA and PI respond similarly to acute CRE and support previously reported data showing a significant mobilization of highly differentiated T-cells. The present study confirms that moderate intensity RE also elicits this response, but highlights potential differences between CRE and RE on the immune responses of T-cells, particularly in PI individuals. Clinical trial registrationThis research study was registered at clinicaltrials.gov NCT03794050