OBJECTIVES: The now commonplace wearing of external nasal splints by sportsmen and athletes has never been scientifically evaluated. The present study looks into the effect of isotonic exercise on nasal resistance, and examines whether this effect is altered by the wearing of an external nasal splint. METHODS: Twenty subjects not suffering from rhinitis were tested. Nasal resistance measurements were recorded using an anterior rhinomanometer before and after isotonic exercise with and without an external nasal splint. Pulse and blood pressure were measured before and after exercise. RESULTS: Significant changes were observed in pulse (p < 0.001) and both systolic (p < 0.002) and diastolic (p < 0.001) blood pressure in response to exercise. Significant differences were seen in nasal resistance when the splint was applied (p < 0.001) and after exercise (p < 0.003). No significant difference was observed after exercise when the splint was worn (p = 0.167). CONCLUSIONS: External nasal splints decrease nasal resistance at rest but are of little value during isotonic exercise.