Respiratory tract symptoms in multi-day trail runners - a focus on allergy.
Introduction: Respiratory tract symptoms (RTS), common in athletes during heavy training and after events, result in impaired readiness for events and race times. Since the 1980’s exercise immunologists have investigated the aetiological factors surrounding the development of exercise induced RTS in order to develop effective preventative strategies. A number of theories have been put forward and explored, such as increased susceptibility to infection, ‘run-away’ inflammatory response and reactivation of prior viral infection. It has been suggested that the mechanisms producing exercise induced inflammation could potentiate allergic responses in sensitized individuals and recently allergic response has been proposed as a potential contributor to exercise induced RTS. Certainly allergic reactions can produce a range of respiratory symptoms; however the relationship between allergic sensitization, allergic reaction and the incidence of post-exercise RTS has not been well defined. Objectives: The primary objective of this study was to document the incidence of RTS for two weeks before and two weeks after a three-day trail run and relate these to the general systemic and salivary immunological profile as well as atopic status of the participants. The secondary objective was to validate the use of the Phadiatop® assay as a predictor of allergy-associated post-race RTS in trail runners. Study Design and Methods: The study formed part of a larger, descriptive field study examining the physiological responses of trail runners during the Three Cranes Challenge, a multi-day 95 km event divided into three stages, in Karkloof, KwaZulu-Natal. Outcome measures examined included self- reported RTS over a 31 day period (pre, during and post race), as well as pre-race Phadiatop® status, salivary IgA (sIgA) concentrations and changes in concentrations of serum IgE (sIgE), cortisol, high sensitivity C-Reactive Protein (hs-CRP) and differential leukocyte counts. The haematological and salivary parameters were obtained at 8 time points before, during and after the event. A convenience sample of 22 individuals was used and two separate analyses were conducted on the data. The inclusion criteria of the first analysis were met by 14 participants. In this analysis, the incidence of RTS was related to each participant’s general immunological profile. Sixteen of the subjects met the inclusion criteria for the second analysis, in which their Phadiatop® status was related to their sIgE and blood eosinophil and basophil concentrations in order to establish the validity of the Phadiatop® assay in predicting the development of allergy–associated postexercise RTS in trail runners. Results: In the first analysis, 78.6 % (n=11) of subjects met the criteria for positive diagnosis of upper respiratory symptoms (URS) during the two week post-race period. In four subjects (36.4 %), URS appeared to be of inflammatory origin, but these were not linked to systemic markers of an allergic response. Of the URS positive subjects, six (54.5 %) presented with markers of infection, three (27.3 %) with markers of a de novo infection and three (27.3%) with a profile suggestive of reactivation of previous infection. Of those presenting with markers of infection 66.7 % (n=4) had concomitantly elevated levels of IgE suggestive of allergic response. There was, however, no evidence of isolated allergic reaction independent of other causes amongst the symptomatic subjects. In the second analysis, 75% (n=12) of runners presented with post-race RTS and seven of these were Phadiatop® positive. In four of the Phadiatop® positive RTS subjects, symptoms appeared to be of allergic origin. Although total IgE concentrations were significantly higher (p< 0.01) in Phadiatop® positive group, there was no significant difference between the eosinophil and basophil concentrations or post-race RTS of the positive and negative groups (p>0.05). Of the four subjects who did not develop RTS, three were Phadiatop® positive. Conclusion: Respiratory tract symptoms in trail runners have a multi-factorial aetiology. A link between concurrent markers of an allergic response and infection is common in symptomatic trail runners. The Phadiatop® assay does not accurately predict the incidence of allergic postexercise RTS in trail runners.