Effects of Resisted Inspiratory Efforts on Immune Cell Mobilization

Acute bouts of physical exercise are a powerful stimulus for leukocyte mobilization into the peripheral circulation, leading to enhanced immunosurveillance and improved immune function when exercise is performed consistently over time. Resistive breathing protocols have emerged as a novel form of exercise training that elicits significant cardiovascular benefits including reductions in blood pressure and sympathetic nervous system activity and enhanced endothelial function. However, the effects of these respiratory training protocols on immune system function are unclear. Here we implemented a single bout of 30 resisted inspiratory efforts (RIE) comprising 5 sets of 6 breaths at 15% or 75% of the individuals’ maximal inspiratory pressure (PI max ) to evaluate the effects on leukocyte mobilization in healthy young adults. Nine healthy adults (5 women; age: 26.11±2.85 years; BMI: 24.12±2.35 kg/m2) participated in a crossover design study, wherein participants were randomized to perform either low (15% PI max ) or high (75% PI max ) RIE on two separate visits separated by at least 48 hours. Blood samples were collected at baseline (Rest), immediately post-RIE (Post), and 10 minutes post-RIE (Recovery). At each time point, leukocytes, including total white blood cells, lymphocytes, natural killer cells (CD56+), and monocytes (CD14+), were analyzed via flow cytometry for identifying cell phenotypes and using a hematology analyzer for blood chemistry data. Leukocyte counts at each time point (i.e., Rest, Post and Recovery) and condition (i.e., high vs low resistance RIE) were assessed via two-way repeated measures ANOVA with Bonferroni post hoc tests (p=0.05). Our analyses show high and low resistance RIE effectively increased total white blood cell counts (p=0.006), total lymphocyte counts (p=0.03), and total monocyte counts (p=0.01) from Baseline to Post. In Recovery, cell counts declined below Baseline (p<0.05) – a response that mirrors the response observed following traditional exercise. Cell counts were not different for high vs. low resistance RIE (p > 0.05) nor were any changes noted in natural killer cell counts across each of the three time points (p > 0.05). Based on these preliminary findings, high and low RIE are effective for short-term (i.e., up to 10 minutes post) leukocytic mobilization. Subsequent studies will explore the potential for RIE when performed daily over 6-12 weeks to effect enduring changes in immune system function including changes in cell phenotype and cytotoxicity. This research was supported in part by a National Institutes of Health R01 Grant (5R01AG065346-05). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.