For years physicians have observed a high incidence of upper respiratory tract infections
(URTI) after strenuous exercise. Mucosal surfaces represent a first-line-of-defense
against infections, and pollutants or organisms entrapped in respiratory secretions
are cleared by mucociliary transport. Little is known about this mechanism during
exercise. The purpose of this study was to examine the nasal mucociliary clearance
(NMCC) in amateur runners competing in a marathon race. Twelve amateur runners entered
in an inner-city marathon race and 10 healthy sedentary subjects participated in the
study. On the day of the race the outside temperature was 3 °C. Nasal mucociliary
transit time (NMTT) was measured daily for 1 week before and 1 week after the race
by the saccharin sodium/indigo carmine method. Nasal tissue biopsies were taken, and
cilia beat frequency (CBF) was measured as viability and function of ciliated epithelial
cells were determined. NMTT was significantly prolonged after the race (17.1 ±1.2
min vs 8.9 ± 0.9 min; athletes vs control group; mean + SEM) and returned to baseline
over several days. CBF was significantly reduced only in the first 24 hours after
the race (7.31 ± 0.65 Hz for athletes vs 9.94 + 0.45 Hz, controls. After the race,
athletes showed a higher percentage of ciliated cells with immotile cilia (37.1 ±
1.3 % vs 27.8 ± 1.1 %, athletes vs controls) or dead ciliated cells (7.3 + 0.9 % vs
4.1 ± 0.8 %). The findings suggest impairment of NMCC up to several days after strenuous
exercise, which might be partially caused by abnormally functioning ciliated cells.
Possible explanations might include exposure to pollutants, cooling of the respiratory
mucosa, altered mucosal bloodflow, and changes in the hydration of the airway surfaces
associated with exercise. Impeded NMCC may contribute to the reported high incidence
of URTI among participants in sports.
Key words
Nasal mucosa - inhaled pollutants - airborne pathogens - sedentary subjects - respiratory
secretions - pharyngeal cavity
