Probiotic Influence On Changes In Core Temperature And The Resultant Changes In Circulating Cytokines Following Aerobic Exercise In A Heated Environment

PURPOSE: Evaluate whether probiotic supplementation affects the relationship between changes in core body temperature and circulating cytokines while cycling in 35 °C. METHODS: 21 men (21 ± 2 yrs; 73.3 ± 13.5 kg; 177.9 ± 8.5 cm; 3.49 ± 0.58 L·min-1) were assigned to either supplementing for 14 days with a placebo (PL), three days (P3), or 14-days (P14) with lactobacillus GG (LGG). On Visit 1, participants provided an informed consent and completed anthropometric measures and a cycling VO2max. Following the supplementation phase, participants returned to cycle in 35 °C for 90-minutes at 60% of VO2max. Before cycling, participants provided a pre-exercise (PRE) blood sample and self-inserted a rectal thermistor to monitor core temperature (Tc). After the cycling bout, participants provided a post-exercise (POST) blood sample. Blood samples were analyzed for circulating concentrations of tumor necrosis factor α (TNFɑ), interleukin (IL)6, and IL10. Change scores (Δ) in circulating cytokines and core temperature from pre- to post-exercise were then calculated and analyzed utilizing a Pearson correlation to examine the relationship between ΔTNFɑ, ΔIL6 and ΔIL10 with ΔTc between PL, P3 and P14. Additionally, the ratio between TNFα, IL-6 and IL-10 with Tc (Δratio) was then calculated and analyzed using a one-way ANOVA between groups. RESULTS: Correlational analysis demonstrated a moderate negative relationship between the ΔIL6 and ΔTc (r2 = -0.642; p = 0.046) in the PL group (Table 1). No significant differences between groups in TNFɑ (F = 1.72; p = 0.206), IL6 (F = 0.57; p = 0.575), or IL10 (F = 0.92; p = 0.420) Δratios were observed. CONCLUSION: Supplementation with LGG did not influence core temperature mediated changes in TNFα, or IL-10. Changes in circulating IL-6, however, demonstrated a moderate relationship with changes in Tc, suggesting LGG supplementation may affect the core temperature mediated response of IL-6 after cycling in 35 °C.