Immune Response of Elite Enduro Racers to Laboratory and Racing Environments: The Influence of Training Impulse and
Lewis Kirkwood1,2, Lesley Ingram-Sills1,2, Mark Dunlop Taylor3
1School of Applied Sciences, Edinburgh Napier University, Edinburgh EH11 4BN, UK.
Introduction:
Understanding the sport-specific immune response elicited during both training and competition is imperative to maximise athlete health and performance. Despite a growing population of professional enduro mountain bike athletes, little is known about the recovery of the immune system following enduro racing events.
Methods:
Nine international level elite enduro mountain bike athletes (age 24.3 ± 2.4 years, height 178.5 ± 8.7 cm, mass 76.5 ± 12.5 kg) completed a laboratory-based maximal exercise test (LAB) on a cycle ergometer and competed in an international mountain bike enduro race event (RACE). Blood samples were taken before, immediately after, and 1 h after LAB and before, 1 h after, and 17 h after RACE. Leukocyte subsets were enumerated using seven-colour flow cytometry. Lucia's training impulse (LuTRIMP) and vibration exposure (VIB) were quantified during RACE.
Results:
Seven participants were included in the final analyses. There was a significant (p < 0.05) increase in neutrophil count alongside a reduction of cytotoxic lymphocyte cell subsets of both the innate (CD3-/CD56+ NK-cells and CD3-/CD56dim NK-cells) and adaptive (CD8+/CD62L-/CD45RA- T-cells and CD8+/CD27+/CD28- T-cells) components of the immune system one hour after RACE. All cell counts returned to baseline values 17 h afterwards (p > 0.05). Cell subset redistribution from pre- to post-one-hour time points (%Δpre-post1h) in cell subsets with potent effector functions (Neutrophils, CD3-/CD56+ NK-cells, CD8+/CD62L-/CD45RA- T-cells, CD8+/CD27+/CD28- T-cells, and CD3-/CD56dim/CD57- NK-cells) was significantly greater at RACE than LAB (p < 0.05). VIB was shown to be a superior predictor of %Δpre-post1h CD4+ T-cells, CD4+ early T-cells, CD4+ naïve T-cells, and NK cells as compared with LuTRIMP on its own (ΔR2 = 0.63 - 0.89, p < 0.05).
Conclusions:
The race event offers a greater challenge to the immune system than LAB, and potentially, whole body vibration is a key component of training load measurement in mountain bike applications.
