A moderate positive correlation was found between the
STT in nonsmokers and RMSSD, SD1, and HF (ms2),
indicating that lower vagal activity is related to a shorter
STT (ie, enhanced mucociliary clearance). This explains
the effect promoted by exercise on the autonomic nervous
system, as demonstrated by the increase in sympathetic
activity and reduction in vagal activity, which affect mucociliary clearance, improving this mechanism after expo-
sure to aerobic exercise.