Aerobic exercises worsen the detection threshold of short H2S pulses

Background Whether smelling is reduced during aerobic exercise is described contradictorily in the sparse literature. Material and Methods To clarify this question, in healthy subjects the passive detection thresholds for short H2S stimuli were determined by means of a flow olfactometer in an inspiration-synchronous manner during nasal breathing in a staircase procedure during a resting phase, a subsequent submaximal load on a bicycle ergometer and a subsequent recovery phase. In parallel, the measurements of heart rate, blood pressure, blood lactate and body temperature were monitored to confirm an aerobic exercise. Results The participants achieved the highest values for the detection threshold in the load phase. By means of rm-ANOVA and post-hoc tests, a significant difference in the mean values of detection thresholds between the measurements at rest and during cycling as well as between the recovery and load phases was observed. However, the mean values of the detection thresholds between the resting and recovery phases did not differ. Conclusion The worsening of olfactory detection thresholds during acute aerobic physical exercise and their immediate improvement during recovery phase to rest values suggests that the detection threshold is influenced by exercise. The most probable cause for this is a dilution effect caused by additional inflowing neutral ambient air in the case of forced nasal breathing.