Relationship between Daily Mileage and Upper Respiratory Illnesses in Collegiate Cross Country Runners

Abstract

The incidence of upper respiratory illnesses (URI) within endurance sports is commonplace and often results in decreased athletic performance. For this reason, avoidance of these illnesses is of utmost importance to the athlete. Previous research has identified a positive relationship between running mileage and frequency of URI; however, defining this threshold in terms of intensity and duration of exercise has not been well established. Little is known about underlying factors influencing this relationship. Greater insight into the relationship between mileage and URI will allow for better training and can help establish best practices for creating programs that can reduce the occurrence of URIs. PURPOSE: The purpose of this study was to investigate the relationship between endurance training and immune function. METHODS: Participants (N = 25, 13 females, 12 males; mean age 19 ± 3 years) were college undergraduate students. A survey consisting of the Wisconsin upper respiratory system measure (WURSS-21), Daily mileage, sleep, and diet logs were kept by each of the cross country athletes throughout the duration of this study. RESULTS: Correlations revealed a significant relationship between daily mileage and frequency of URI (r = .10, p = .05). Additionally, sleep and diet were significantly correlated with both mileage and URI frequency, which fulfilled prerequisites to test for moderation (Aiken & West, 1991). However, when sleep and diet were added to the model, neither was found to moderate the relationship between mileage and URI. CONCLUSION: Results suggest that as daily mileage increases there is a greater likelihood of URI. It was also revealed that vitamin C intake and hours of sleep did not affect this relationship. Future research on this should explore other factors that could potentially influence the relationship between miles run per day and URI.