BackgroundThis 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 FATmin point.MethodsBreath-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 VO2 at AnT and at FATmin.ResultsMaximal oxygen uptake (VO2max) was 56.17 ± 4.95 and 46.04 ± 3.25 ml kg−1 min−1 in ATL and NATL, respectively. In ATL, AnT was observed at 87.57 ± 1.30 % of VO2max and FATmin was observed at 87.60 ± 1.60 % of VO2max. In NATL, AnT and FATmin were at 84.64 ± 1.10 % of VO2max and 85.25 ± 1.10 % of VO2max, respectively. Our data show large correlations between VO2 at AnT and VO2 at FATmin for 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.ConclusionsOur results show high correlation between AnT and FATmin in both ATL and NATL with equal substrate oxidation rates at AnT.

In this study, we aimed to determine the exercise intensities eliciting the highest (FAT max ) and the lowest (FAT min ) fat oxidation rate in male cyclists and to compare these intensities with their individual aerobic (AeT) and anaerobic (AnT) thresholds, respectively. Twenty-two moderately trained male cyclists performed a 2-min stage graded exercise test until exhaustion using breath-by-breath gas analysis to determine maximal oxygen consumption (VO 2max ). The fat oxidation rate was calculated using a stoichiometric equation, with metabolic thresholds being determined by ventilatory gas analysis. In the present group of subjects, FAT max was found at a 21.34 ± 3.64 ml•kg −1 •min −1 corresponding to 45.05 ± 7.68% VO 2max . AeT occurred at an exercise intensity of 22.15 ± 4.84 ml•kg −1 •min −1 , matching 46.76 ± 10.24% VO 2max . AnT and FAT min were located at intensities equivalent to 32.56 ± 5.52 ml•kg −1 •min −1 and 32.30 ± 5.35 ml•kg −1 •min −1 which corresponded to 68. 74 ± 11.65 and 68.19 ± 11.29% VO 2max , respectively. The correlation between FAT max and AeT was strong (r = 0.80, p < 0.05). No statistical difference was observed between FAT min and AnT (r = 0.99, p < 0.05). The strong relationship between observed indices can be used to provide a more tailored exercise approach.

Background: The aim of this trial was to assess the feasibility of the future definitive study that will define the effects of aerobic threshold based exercise on ventilatory efficiency in sedentary adult female asthma patients. Methods: Six female asthma patients performed an individualized aerobic training program for 7 weeks with their ventilatory parameters measured before and after exercise intervention using breath-by-breath gas analysis and graded treadmill test until volitional exhaustion. Paired samples t-test was used to compare baseline and control values. Results: Statistically significant changes in resting ventilatory equivalents for oxygen and carbon-dioxide, increases in exercise capacity, decrease of nadir ventilatory equivalents for oxygen and carbon-dioxide values and a shift of the aerobic threshold and associated heart rate toward higher exercise intensity were noted as a result of training adaptation (p < 0.05). The participants' medicament diary demonstrated a decrease in daily inhaled therapy and in personal rating of perceived exertion (p < 0.05). Conclusions: These results suggest feasibility of individual aerobic threshold based exercise contribution toward asthma control in asthma patients.

No abstract

Regular exercise at the intensity matching maximal fat oxidation (FATmax) has been proposed as a key element in both athletes and clinical populations when aiming to enhance the body’s ability to oxidize fat. In order to allow a more standardized and tailored training approach, the connection between FATmax and the individual aerobic thresholds (AerT) has been examined. Although recent findings strongly suggest that a relationship exists between these two intensities, correlation alone is not sufficient to confirm that the intensities necessarily coincide and that the error between the two measures is small. Thus, this systematic review and meta-analysis aim to examine the agreement levels between the exercise intensities matching FATmax and AerT by pooling limits of agreement in a function of three parameters: (i) the average difference, (ii) the average within-study variation, and (iii) the variation in bias across studies, and to examine the influence of clinical and methodological inter- and intra-study differences on agreement levels. This study was registered with PROSPERO (CRD42021239351) and ClinicalTrials (NCT03789045). PubMed and Google Scholar were searched for studies examining FATmax and AerT connection. Overall, 12 studies with forty-five effect sizes and a total of 774 subjects fulfilled the inclusion criteria. The ROBIS tool for risk of bias assessment was used to determine the quality of included studies. In conclusion, the overall 95% limits of agreement of the differences between FATmax and AerT exercise intensities were larger than the a priori determined acceptable agreement due to the large variance caused by clinical and methodological differences among the studies. Therefore, we recommend that future studies follow a strict standardization of data collection and analysis of FATmax- and AerT-related outcomes.

Over the past two decades, scientists have attempted to evaluate whether the point of maximal fat oxidation (FATmax) and the aerobic threshold (AerT) are connected. The existence of such a relationship would allow a more tailored training approach for athletes while improving the efficacy of individualized exercise prescriptions when treating numerous health-related issues. However, studies have reported conflicting results, and this issue remains unresolved. This systematic review and meta-analysis aimed: (i) to examine the strength of the association between FATmax and AerT by using the effect size (ES) of correlation coefficient (r) and standardized mean difference (SMD); (ii) to identify potential moderators and their influence on ES variability. This study was registered with PROSPERO (CRD42021239351) and ClinicalTrials (NCT03789045). PubMed and Google Scholar were searched and fourteen articles, consisting of overall 35 ES for r and 26 ES for SMD were included. Obtained ESs were analyzed using a multilevel random-effects meta-analysis. Our results support the presence of a significant association between FATmax and AerT exercise intensities. In conclusion, due to the large ES variance caused by clinical and methodological differences among the studies, we recommend that future studies follow strict standardization of data collection and analysis of FATmax and AerT-related outcomes.

We aimed to determine the exercise intensity eliciting the highest (FATmax) and the lowest (FATmin) fat oxidation rate in sedentary men with obesity and to examine if these intensities correlate with their individual aerobic (AeT) and anaerobic (AnT) thresholds, respectively. Nineteen obese males performed breath-by-breath analysis to assess maximal oxygen consumption (VO2max) and to calculate their fat oxidation rate. Pearson correlation coefficient (r), coefficient of determination (R2) and paired t-test were used to evaluate VO2 at AeT and at FATmax and VO2 at AnT and at FATmin, respectively. FATmax and AeT occurred at 42.80±2.68% of VO2max and 43.02±2.73% of VO2max, while FATmin and AnT occurred at 53.40±3.65% of VO2max and 53.38±3.65% of VO2max, respectively. A high correlations were found between intensities matching FATmax and AeT (r=0.86, P<0.01) and those at FATmin and at AnT (r=0.99, P<0.01). The existing correlations suggest that metabolic thresholds may be used as exercise intensity markers assuring more tailored exercise approach in men with obesity.

No abstract