Introduction Nitric oxide (NO) regulates blood flow and both muscle contraction and metabolism during exercise. The plasma levels of NO increase after exercise. However, studies that determined the association between the levels of salivary NO and regular exercise are also lacking. The aim of this study was to assess the relationship of the levels of salivary NO with physical activity among Korean elderly.

Methods 176 subjects aged 48–84 years old were cross-sectionally surveyed. All participants underwent oral and general examination. Age, gender, education level, regular exercise, smoking were evaluated through interview. Periodontal health status was evaluated by clinical attachment loss over 6 mm (CAL6 mm) for six points of 12 index teeth (total 72 sites). The number of CAL6 mm sites and the number of teeth were counted. Fasting plasma glucose level and blood pressure were measured. Unstimulated saliva was collected for 10 min. Salivary NO was determined by the Griess reagent. ANCOVA and Multiple linear regression analyses were applied.

Results After correcting for differences in for age, gender, the number of CAL6 mm sites, the number of teeth, pH in saliva, salivary flow rate, fasting plasma glucose level, systolic blood pressure and diastolic blood pressure, those who exercise everyday had the lowest salivary NO level (66.9 umol/l vs 104.3 umol/l and 121.3 umol/l, p=0.082), which is not significant. Salivary NO levels had a dose-effect relationship with the frequency of regular exercise (β=−13.5, p=0.022).

Conclusion The results of the present study suggest that regular exercise may induce lower levels of NO.