title: Fat Utilization During High-Intensity Exercise: When Does It End?
abstract: BACKGROUND
  This study examined substrate oxidation at high-intensity exercise and aimed to determine when fat oxidation ends (FATmin). We hypothesized the existence of a connection between the anaerobic threshold (AnT) and FATminpoint.
  
  
  METHODS
  Breath-by-breath data obtained from indirect calorimetry during a graded treadmill test were used to measure substrate oxidation and maximal oxygen uptake (VO2max) on 47 males (30 athletes (ATL) and 17 non-athletes (NATL)). Pearson correlation coefficient (r) and effect size (R2) were used to test correlations between VO2at AnT and at FATmin.
  
  
  RESULTS
  Maximal oxygen uptake (VO2max) was 56.17 ± 4.95 and 46.04 ± 3.25 ml kg-1min-1in ATL and NATL, respectively. In ATL, AnT was observed at 87.57 ± 1.30 % of VO2maxand FATminwas observed at 87.60 ± 1.60 % of VO2max.In NATL, AnT and FATminwere at 84.64 ± 1.10 % of VO2maxand 85.25 ± 1.10 % of VO2max, respectively. Our data show large correlations between VO2at AnT and VO2at FATminfor ATL (r = 0.99, p < 0.01, 95 % CI 0.99 to 1.00) and NATL (r = 0.97, p < 0.01, 95 % CI 0.91 to 0.98). The effect size of correlations for ATL and NATL were 0.98 and 0.94, respectively.
  
  
  CONCLUSIONS
  Our results show high correlation between AnT and FATminin both ATL and NATL with equal substrate oxidation rates at AnT.
authors.affiliation: Institute for Sport and Occupational Medicine Banja Luka, Zdrave Korde 4, 78000, Banja Luka, Bosnia and Herzegovina. ratkoperic@yahoo.com.
authors.forename: Ratko
authors.initials: R
authors.lastname: Peric
authors.affiliation: Department of Health and Exercise Science, Appalachian State University, Boone, NC, USA.
authors.forename: Marco
authors.initials: M
authors.lastname: Meucci
authors.affiliation: Department of Biochemistry, Aspire Academy, Doha, Qatar.
authors.forename: Zoran
authors.initials: Z
authors.lastname: Nikolovski
keywords: Anaerobic threshold; Fat; High intensity; Oxidation; Running