T-cell counts in response to acute cardiorespiratory or resistance exercise in physically active or physically inactive older adults: a randomized crossover study.

T cells often undergo age-related changes, which may be offset by regular exercise training. However, the majority of literature is derived from cardiorespiratory exercise studies. The purpose of this study was to examine the effects of acute cardiorespiratory exercise and acute resistance exercise on the T-cell response among physically active (PA) older adults compared with physically inactive (PI) older adults. Twenty-four healthy older adults [PA n = 12; PI n = 12; means ± SD; age (years) PA 62 ± 5, PI 64 ± 5; body mass index (BMI; kg/m2) PA 23.9 ± 3.0, PI 25.6 ± 3.5] completed one bout each of matched intensity cardiorespiratory exercise and resistance exercise in a randomized order. Blood samples drawn preexercise, postexercise, and 1 h postexercise (recovery) were analyzed by flow cytometry for T cells and T-cell subsets. Resistance exercise mobilized more T-cell subsets in PI (10 of the measured types, including total T cells; CD45RA+ CD62L+, CD45RA- CD62L+, CD45RA- CD62L-, and CD45RA+ CD62L- T cells), whereas cardiorespiratory exercise mobilized more subsets in PA (CD45RA+ CD62L- and CD57+ CD45RA+ CD62L- CD4+ T cells). Both cardiorespiratory exercise and resistance exercise elicited a significant (P < 0.05) mobilization of highly differentiated (CD45RA+ CD62L-; CD57+ CD45RA+ CD62L-) CD8+ T cells into the circulation postexercise in both PA and PI groups. Furthermore, cardiorespiratory exercise resulted in a decrease in the number of circulating Th17 cells postexercise, whereas resistance exercise increased Th17 cell mobilization compared with the cardiorespiratory exercise response. There are differences between cardiorespiratory exercise and resistance exercise on the immune responses of T cells, particularly in PI individuals. This research study was registered at clinicaltrials.gov NCT03794050. NEW & NOTEWORTHY A bout of resistance exercise did not elicit the same T-cell responses as a bout of walking on a treadmill, and the response was also not the same for people who participate in regular exercise compared with those who do not. Although there were several similarities, these potential differences underscore the importance of careful selection of exercise protocol based on the population studied and the desired T-cell response to exercise outcome.

CD4+ T cell activation and associated susceptibility to HIV-1 infection in vitro increased following acute resistance exercise in human subjects.

Early studies in exercise immunology suggested acute bouts of exercise had an immunosuppressive effect in human subjects. However, recent data, show acute bouts of combined aerobic and resistance training increase both lymphocyte activation and proliferation. We quantified resistance exercise-induced changes in the activation state of CD4+ T lymphocytes via surface protein expression and using a medically relevant model of infection (HIV-1). Using a randomized cross-over design, 10 untrained subjects completed a control and exercise session. The control session consisted of 30-min seated rest while the exercise session entailed 3 sets × 10 repetitions of back squat, leg press, and leg extensions at 70% 1-RM with 2-min rest between each set. Venous blood samples were obtained pre/post each session. CD4+ T lymphocytes were isolated from whole blood by negative selection. Expression of activation markers (CD69 & CD25) in both nonstimulated and stimulated (costimulation through CD3+ CD28) cells were assessed by flow cytometry. Resistance exercised-induced effects on intracellular activation was further evaluated via in vitro infection with HIV-1. Nonstimulated CD4+ T lymphocytes obtained postexercise exhibited elevated CD25 expression following 24 h in culture. Enhanced HIV-1 replication was observed in cells obtained postexercise. Our results demonstrate that an acute bout of resistance exercise increases the activation state of CD4+ T lymphocytes and results in a greater susceptibility to HIV-1 infection in vitro. These findings offer further evidence that exercise induces activation of T lymphocytes and provides a foundation for the use of medically relevant pathogens as indirect measures of intracellular activation.