田原 麗衣

Background: Excessive production of salivary nitric oxide (s-NO) is a risk factor for oral diseases such as Sjögren syndrome and periodontal disease. Although s-NO is known to be affected by exercise, it is unclear how the difference in exercise intensities affects the s-NO response. Objectives: The purpose of this study was to investigate the acute effect of different exercise intensities (high vs. low intensity) on s-NO production using a cross-over design. Methods: Five healthy male young adults (21.6 ± 0.9 years) performed two ergometer exercises for 30 min at different exercise intensities: 50% heart rate (HR)reserve (low-intensity condition) and 80% HRreserve (high-intensity condition). Saliva samples were collected before (pre) and after (post 0-h and post 1-h) exercises. Results: The s-NO concentration significantly increased (P < 0.05) after the high-intensity exercise (∆changes in post 0-h; +244 ± 53 µmol/L, post 1-h; +352 ± 58 µmol/L), but the s-NO concentration did not change after the low-intensity exercise (∆changes in post 0-h; +11 ± 37 µmol/L, post 1-h; +64 ± 69 µmol/L). Conclusions: This study reveals that s-NO production is dependent on exercise intensities, suggesting that low-intensity exercise can be possible without increasing the risk of oral diseases.

Background: High-intensity exercise affects the level of salivary nitric oxide (NO) with an impact on oxidative stress such as a reactive nitrogen-oxide species. However, in athletes with high-intensity training, the relationship between salivary NO levels and oxidative stress is yet to be clear. Additionally, the association of salivary NO levels and the common health disorders of athletes is unknown. Thus, the aim of this cross-sectional study was to clarify the relationship between salivary NO levels and oxidative stress, and the health/medical disorders existing in elite class university athletes. Methods: In 250 athletes (males, 151 and females, 99) from undergraduate levels of Japanese University, we investigated the relationship between levels of salivary NO and oxidative stress markers: derived reactive oxygen species (d-ROMs) and biological antioxidant potential (BAP), and also examined that whether salivary NO levels are associated with diseases. Results: There were no significant association between the levels of salivary NO and oxidative stress markers (such as d-ROM and BAP). From the questionnaire, asthma was the most prevalent as evident from medical history of the athletes. Additionally, the salivary NO levels were higher (520 ± 43 µmol/L vs. 375 ± 13 µmol/L, P < 0.05) in the asthma group (n = 9) than in the non-asthma group (n = 241). We determined the optimal cut-off value (P = 0.019) of the salivary NO levels for asthma was 425 µmol/L, with a sensitivity of 88.9% and specificity of 61.8% (area under the curve (AUC), 0.73). Conclusions: Our results suggest that the high levels of salivary NO in trained university athletes in Japan may potentially predict asthma. And this salivary NO level is not associated with markers of oxidative stress and existing diseases in athletes studied here.