Previous research indicates that the composition and diversity of the gut and lung microbiome is associated with many autoimmune and inflammatory diseases. However, aerobic exercise has recently been shown to preferentially shift the composition of the gut microbiome. The physiological significance of these changes is not well understood, and currently there are no published data exploring whether physical activity may impact the composition and diversity of the oral microbiome. PURPOSE: We conducted this exploratory analysis to determine whether the composition of the oral microbiome was impacted by habitual physical activity (PA) level. METHODS: Sixteen young adults between the ages of 18- 35 years (n=8 physically inactive (PI) subjects accumulating <30 minutes of planned exercise per week; n=8 trained athletes (TA) >150 minutes of moderate-to-vigorous PA per week) visited the laboratory after an overnight fast and without using any toothpaste or antibacterial mouthwash for 24 hours. Upon arrival to the laboratory, body composition assessment and PA questionnaires were administered, followed by saliva and sputum sample collection. Processing and DNA extraction was performed on samples within 48 hours of collection, and the bacterial 16S rNA gene was amplified followed by sequencing. Subjects were given an accelerometer to wear around their waist for one week to verify chronic PA level. Principle components analysis followed by linear regression was used to compare oral microbial taxonomy across PA levels. RESULTS: PI and TA had significantly different chronic PA levels (PI: 240±26 METS/wk, TA: 3810±1656 METS/wk) (p<0.01). The amount of vigorous PA that subjects accumulated in METS/week explained 19.69% of the composition in the oral microbiome. Of particular interest, Veillonella spp., Streptococcus spp., Gemella spp. and Enterococcus spp. were significantly higher in PI versus TA (p<0.05, respectively), which have been associated with various types of lung diseases, including chronic obstructive pulmonary disease and asthma. CONCLUSION: These data indicate that: (1) habitual PA level differentially impacts the oral microbiome and (2) that the amount of vigorous activity accumulated per week explains a significant portion of the variance in the oral microbiota composition.