Breath acetone change during aerobic exercise is moderated by cardiorespiratory fitness

Karsten Königstein, Sebastian Abegg, Andrea N Schorn, Ines C Weber, Nina Derron,
Andreas Krebs, Philipp A Gerber, Arno Schmidt-Trucksass and Andreas T Güntner

J. Breath Res. 15 (2021) 016006

Exhaled breath acetone (BrAce) was investigated during and after submaximal aerobic exercise as a
volatile biomarker for metabolic responsiveness in high and lower-fit individuals in a prospective
cohort pilot-study. Twenty healthy adults (19–39 years) with different levels of cardiorespiratory
fitness (VO2peak), determined by spiroergometry, were recruited. BrAce was repeatedly measured
by proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS) during 40–55 min
submaximal cycling exercise and a post-exercise period of 180 min. Activity of ketone and fat
metabolism during and after exercise were assessed by indirect calorimetric calculation of fat
oxidation rate and by measurement of venous β-hydroxybutyrate (βHB). Maximum BrAce ratios
were significantly higher during exercise in the high-fit individuals compared to the lower-fit group
(t-test; p = 0.03). Multivariate regression showed 0.4% (95%-CI = −0.2%–0.9%, p = 0.155)
higher BrAce change during exercise for every ml kg−1 min−1 higher VO2peak. Differences of BrAce
ratios during exercise were similar to fat oxidation rate changes, but without association to
respiratory minute volume. Furthermore, the high-fit group showed higher maximum BrAce
increase rates (46% h−1) in the late post-exercise phase compared to the lower-fit group
(29% h−1). As a result, high-fit young, healthy individuals have a higher increase in BrAce
concentrations related to submaximal exercise than lower-fit subjects, indicating a stronger
exercise-related activation of fat metabolism.