Personal mobile tracking of resting and excess post-exercise oxygen consumption with a mobile indirect calorimeter

BACKGROUND: Excess post-exercise oxygen consumption (EPOC) is indicative of the effect of exercise on tissue repair and recovery from exercise. Detection of EPOC has been performed by indirect calorimetry (IC) on the breath of study subjects, and conducted in professional facilities with reference instruments requiring calibration, power, or/and professional expertise. However, no study has investigated EPOC in a mobile IC device before. Given the increasing use of mobile technologies, which is less expensive, portable, battery-operated, light-weight, user-friendly, and most importantly, easily access anywhere/anytime, individuals can now track their physical performances via mobile health devices independently and confidently. METHODS: In this study, we want to apply a mobile IC technology to examine energy expenditure (EE) in parallel with to evaluate accessibility of EPOC on high-intensity interval training (HIIT) for 6 weeks, as well as the effect on muscle change. Twenty-nine subjects (16 males and 13 females), BMI (17.3-31.8), aged (20-42 years) are divided into a control group (CG, N.=11) and a HIIT intervention group (IG, N.=19). The subjects self-monitor their EPOC with a personal mobile IC device (Breezing^®). All 29 subjects conducted over 340 measurements for the entire study. RESULTS: EPOC effect was measured on HIIT days, and significant differences in EPOC from IG HIIT days vs. IG non-HIIT days as well vs. CG non-HIIT days (P<0.01) (α=0.05) were detected. The capability to grow muscle mass after 6 weeks of HIIT training emerged in IG vs. CG. IG subjects with 6% or greater muscle change also demonstrated higher EPOC effect (average 247 kcal/day) vs. IG subjects with less than 1% muscle change (average 47 kcal/day). CONCLUSIONS: Independent IC tracking of EPOC was feasible with the mobile device and correlated with higher muscle growth in IG. Thus, personal EPOC may inform about exercise recovery and long-term muscle mass change.