Effects of acute heat exposure on monocyte phenotype following exhaustive exercise: An ex vivo study

Background/Aim: This study aimed to evaluate the effects of ex vivo whole blood heat therapy on monocyte inflammatory response following exhaustive exercise in young individuals. Methods: Eight recreationally endurance trained individuals (27.2 ± 3.1 years old, VO₂Peak 53.1 ± 2.1 mL/kg/min) performed a strenuous step-up/step-down protocol until exhaustion. Blood samples were collected pre and post exercise and incubated 37 °C or 40 °C during 2 h. Flow cytometry was used to assess TLR-4 expression, NF-kB activation, mitochondrial membrane potential and TNF-alpha expression in CD14+ monocytes. Results: Post exercise, TLR-4 expression and NF-kB activation increased at 37 °C (p < 0.001), but heat therapy at 40 °C significantly reduced these responses (p < 0.01). MMP decreased after exercise at both temperatures but was significantly lower at 37 °C than 40 °C (p < 0.05). TNF-a levels showed a trend toward returning to baseline with heat therapy. Conclusion: Ex vivo heat therapy reduces monocyte mediated inflammation after exercise, induced muscle damage, suggesting its potential as a recovery strategy to strenuous exercise sessions.