Circulating angiogenic cell response to sprint interval and continuous exercise

Introduction: Although commonly understood as immune cells, certain T lymphocyte and monocyte subsets have angiogenic potential, contributing to blood vessel growth and repair. These cells are highly exercise responsive and may contribute to the cardiovascular benefits seen with exercise.

Purpose: To compare the effects of a single bout of continuous (CONTEX) and sprint interval exercise (SPRINT) on circulating angiogenic cells (CAC) in healthy recreationally active adults.

Methods: Twelve participants (aged 29 ± 2 years, BMI 25.5 ± 0.9 kg m⁻² , V˙O₂ peak 44.3 ± 1.8 ml kg⁻¹  min⁻¹; mean ± SEM) participated in the study. Participants completed a 45-min bout of CONTEX at 70% peak oxygen uptake and 6 × 20 s sprints on a cycle ergometer, in a counterbalanced design. Blood was sampled pre-, post-, 2 h and 24 h post-exercise for quantification of CAC subsets by whole blood flow cytometric analysis. Angiogenic T lymphocytes (T_ANG) and angiogenic Tie2-expressing monocytes (TEM) were identified by the expression of CD31 and Tie2, respectively.

Results: Circulating (cells µL⁻¹) CD3⁺CD31⁺ T_ANG increased immediately post-exercise in both trials (p < 0.05), with a significantly greater increase (p < 0.05) following SPRINT (+ 57%) compared to CONTEX (+ 14%). Exercise increased (p < 0.05) the expression of the chemokine receptor CXCR4 on T_ANG at 24 h. Tie2-expressing classical (CD14⁺⁺CD16⁻), intermediate (CD14⁺⁺CD16⁺) and non-classical (CD14⁺CD16⁺⁺) monocytes and circulating CD34⁺ CD45^dim progenitor cells were higher post-exercise in SPRINT, but unchanged in CONTEX. All post-exercise increases in SPRINT were back to pre-exercise levels at 2 h and 24 h.

Conclusion: Acute exercise transiently increases circulating T_ANG, TEM and progenitor cells with greater increases evident following very high intensity sprint exercise than following prolonged continuous paced endurance exercise.