Relationship Between VO2 And Acetone In Exhaled Breath Acetone Relationship

PURPOSE: Exercise intensity governs energy demand which, in turn, governs metabolism. The relationship between breath acetone and fat oxidation renders it a potential tool in the application of non-invasive metabolic analysis. Contrasting two different exercise intensities and monitoring single breath acetone can provide insight into the proposed hypothesis that breath acetone increases with exercise intensity METHODS: Twenty two male participants (age 22+/- 2.6 years, body mass 74.7+/- 10.7 kg, and stature 181.5 +/- 5.9 cm) completed two visits i) a familiarisation and V̇O2 max test (mean 54.1 +/- 9.3 ml/kg/min) on a cycle ergometer to determine visit two exercise intensities ii) Finger-prick blood samples and Bio VOC single distal breath samples were taken at five time points throughout visit two: after 20 minutes rest (rest), after 10 minutes of sub-maximal intensity cycling (50% of V̇O2 max), after 10 bouts of max intensity cycle sprints (max) and after 8 minutes (R1) and 20 minutes (R2) of recovery. Heart rate and rate of perceived exertion were monitored throughout both trials. RESULTS: A significant percentage increase from resting baseline in breath acetone was detected after 10 minutes of sub-maximal exercise (23.5% change in m/z 59 ion with 500mn scan time, p = 0.42 with moderate effect size). There was no significant change in breath acetone between sub-maximal exercise and maximal exercise (>10% p > 0.05). Breath acetone then returned to resting values after 8 minutes of recovery. A possible relationship between breath acetone and V̇O2max (workload) was identified and explored (spearmans rank correlation r = 0.876). CONCLUSIONS: In line with previous research, the sub-max intensity exercise increased single distal breath acetone. In contrast to previous literature, that claims breath acetone increases with increases in exercise intensity, this study found that the onset of maximal intensity exercise has no further significant increase in breath acetone. Exercise of an intensity greater than moderate have rarely been studied in acetone analysis. The current study suggests there may be a limit on the increases in acetone with exercise intensity. Further studies incorporating a larger cohort, possibly in a trained population will provide a greater understanding of this relationship. EPSRC PhD scholarship Tomo Rosser