Using a short-duration step protocol and continuous indirect calorimetry, whole-body rates of fat and carbohydrate oxidation can be estimated across a range of exercise workloads, along with the individual maximal rate of fat oxidation (MFO) and the exercise intensity at which MFO occurs (Fatmax). These variables appear to have implications both in sport and health contexts. After discussion of the key determinants of MFO and Fatmax that must be considered during laboratory measurement, the present review sought to synthesize existing data in order to contextualize individually measured fat oxidation values. Data collected in homogenous cohorts on cycle ergometers after an overnight fast was synthesized to produce normative values in given subject populations. These normative values might be used to contextualize individual measurements and define research cohorts according their capacity for fat oxidation during exercise. Pertinent directions for future research were identified.

/pdf/contextualising-maximal-fat-oxidation-during-exercise-4pkay7u5ct.pdf

Contextualising Maximal Fat Oxidation During Exercise: Determinants and Normative Values.

Objective: To investigate the effect of a multistage ultra-endurance triathlon on body composition in ultra-triathletes. Design: Descriptive field study. Setting: The “World Challenge Deca Iron Triathlon 2006” in Monterrey, Mexico, in which every day for 10 consecutive days athletes had to perform the distance of one Ironman triathlon. Subjects: Eight male ultra-endurance athletes (mean (SD) age 40.6 (10.7) years, weight 76.4 (8.4) kg, height 175 (4) cm and body mass index (BMI) 24.7 (2.2) kg/m2). Interventions: None. Main outcome measurements: Determination of body mass, protein mass, body fat, per cent body fat, mineral mass, total body water, intracellular water, extracellular water and lean body mass with a direct segmental multifrequency bioelectrical impedance method before the race and after each stage in order to show changes in body composition. Results: A statistically significant decrease of body mass (−2.4 kg, p = 0.014), body fat (−5 kg, p = 0.0078) and per cent body fat (−6.4%, p = 0.0078) occurred at the end of the first day compared to values taken in the pre-race period. In contrast, at the same time, a statistically significant increase of protein mass (+0.7 kg, p = 0.035), mineral mass (+0.2 kg, p = 0.04), total body water (+1.8 litres, p = 0.042), intracellular water (+1.6 litres, p = 0.034) and lean body mass (+2.6 kg, p = 0.023) was shown. After the first day until the end of the challenge, body fat (−3 kg, p>0.05) and per cent body fat (−3.9%, p>0.05) showed a statistically significant decrease, whereas the other parameters showed no changes. Conclusions: Athletes taking part in a multistage ultra-endurance triathlon over 10 Ironman triathlon distances in 10 consecutive days lost 3 kg of body fat; skeletal muscle mass, mineral mass and body water were unchanged.

/pdf/effect-of-a-multistage-ultra-endurance-triathlon-on-body-3fclsblmou.pdf

Effect of a multistage ultra-endurance triathlon on body composition: world challenge deca iron triathlon 2006

BYRNE, N. M., and A. P. HILLS. Relationships between HR and VO2 in the obese. Med. Sci. Sports Exerc., Vol. 34, No. 9, pp. 1419–1427, 2002.PurposeTo enable more targeted exercise prescription for the obese, the purpose of this study was to consider relationships between relative indices of VO2peak

Relationships Between HR and VO2 in the Obese

Maximal fat oxidation during exercise (MFO) and the exercise intensity eliciting MFO (Fatmax ) are considered biological markers of metabolic health and performance. A wide range of studies have been performed to increase our knowledge about their regulation by exercise and/or nutritional intervention. However, numerous data collection and analysis approaches have been applied, which may have affected the MFO and Fatmax estimation. We aimed to systematically review the available studies describing and/or comparing different data collection and analysis approach factors that could affect MFO and Fatmax estimation in healthy individuals and patients. Two independent researchers performed the search. We included all original studies in which MFO and/or Fatmax were estimated by indirect calorimetry through an incremental graded exercise protocol published from 2002 to 2019. This systematic review provides key information about the factors that could affect MFO and Fatmax estimation: ergometer type, metabolic cart used, warm-up duration and intensity, stage duration and intensities imposed in the graded exercise protocol, time interval selected for data analysis, stoichiometric equation selected to estimate fat oxidation, data analysis approach, time of the day when the test was performed, fasting time/previous meal before the test, and testing days for MFO/Fatmax and maximal oxygen uptake assessment. We suggest that researchers measuring MFO and Fatmax should take into account these key methodological issues that can considerably affect the accuracy, validity, and reliability of the measurement. Likewise, when comparing different studies, it is important to check whether the above-mentioned key methodological issues are similar in such studies to avoid ambiguous and unacceptable comparisons.

Assessment of maximal fat oxidation during exercise: A systematic review.

We investigated the change of body composition in ultra- endurance runners during a multi-stage ultra-endurance run, the Isarrun 2006 in Bavaria, Germany, where athletes had to run 338 km within 5 days. Body mass, skin fold thicknesses and circumferences of extremities were measured in 21 well-experienced extreme endurance male runners (mean ± SD, 41.5 ± 6.9 years, 72.6 ± 6.4 kg, 178 ± 5 cm, BMI 23.0 ± 2.0 kg·m(-2)), who finished mainly within the first half of the ranking, in order to calculate skeletal muscle mass and body fat mass to prove changes after the race. Body mass and calculated fat mass did not change significantly (p>0.05), but, calculated skeletal muscle mass decreased significantly (p<0.05) by 0.63 ± 0.79 kg by the end of the race. The most apparent decline (p<0.01) of the calculated skeletal muscle mass was during the first stage, and no changes were observed during the last 4 stages. We conclude, that a multi- stage ultra-endurance run over 338 km within 5 days leads to no changes of body mass or body fat mass, but a statistically significant decrease of skeletal muscle mass of 0.63 ± 0.79 kg by the end of the race in well-trained and well-experienced ultra-endurance runners. The change of skeletal muscle mass has to be evaluated in further studies at ultra-endurance races with suitable methods to detect changes in hydration status and water metabolism. Key pointsUltra-runners at the Isarrun 2006 suffered no loss of body mass.Skeletal muscle mass decreased highly significantly during the first stage but no significant changes of skeletal muscle mass were observed during the following 4 stages of the Isarrun 2006.Body fat mass remained stable during the Isarrun 2006.

https://www.jssm.org/hfpdf.php?volume=06&issue=4&page=401

Running 338 Kilometres within Five Days has no Effect on Body Mass and Body Fat But Reduces Skeletal Muscle Mass - the Isarrun 2006.

The aim of this case study was to examine energy expenditure (EE) in one cyclist during an extreme endurance cycling race - the "XXAlps 2004" (2,272 km distance and 55,455 m altitude) which was completed in 5 days and 7 hours - and whether the energy deficit derives primarily from the degradation of subcutaneous adipose tissue or loss of muscle mass. Energy intake (EI) was continuously recorded. EE was estimated using two different methods: 1) Continuous heart rate recording using a portable heart rate monitor (POLAR(®) S710) and 2) using the individual relationship between heart rate and oxygen uptake (VO2) determined under laboratory conditions. Body composition was assessed by measuring body mass, skinfold thickness and extremity circumferences. The cyclist lost 2.0 kg body mass, corresponding to 11,950 kcal (50 MJ). Fat mass was reduced by 790 g (7,110 kcal; 30 MJ) and fat free mass by 1.21 kg (4,840 kcal; 20 MJ). Circumferences of the lower extremities were reduced, in contrast skinfold thickness at the lower limbs increased. Energy deficit (ED) was calculated as the difference between EI and EE. Energy deficit using continuous heart rate monitoring was 29,554 kcal (124 MJ), and using the individual relationship between heart rate and VO2 was 7,111 kcal (30 MJ). The results show that the difference between ED due to decreased body mass and ED estimated from continuous heart rate monitoring was 74 MJ (124 MJ - 50 MJ). In contrast the difference between ED due to decreased body mass and ED estimated from laboratory data was 20 MJ (30 - 50 MJ). This difference between methodologies cannot properly be explained. Body mass and skinfold thickness may be overestimated due to hypoproteinemic oedemas during endurance exercise. Data from the present study suggests the individual relationship between heart rate and VO2 may provide a closer estimation of EE during extreme endurance exercise compared with corresponding data derived from continuous heart rate monitoring using the POLAR(®) S710. Key PointsDuring an extreme endurance cycling race, energy expenditure can not be covered by energy intake and an energy deficit results.The energy deficit seems to be covered by degradation of subcutaneous adipose tissue and muscle mass.Determination of energy expenditure during extreme endurance may be properly determined with the individual correlation of heart rate - VO2 instead of continuous heart rate monitoring.

http://www.jssm.org/hfpdf.php?volume=05&issue=1&page=154

Effects of an extreme endurance race on energy balance and body composition - a case study.

In this study we determined the exercise intensity that elicits the highest fat oxidation rate in 15 obese women and 13 obese men. Furthermore the relationship between this intensity with the lactate (LT) and ventilatory thresholds (VT) was investigated in order to give training recommendation for maximal fat utilization during endurance exercise. After an incremental exercise test until exhaustion on a cycle ergometer, subjects performed six 20-min exercise bouts of 25, 35, 45, 55, 65 and 75% VO2peak. The 20 min stages were randomly assigned and spread over two separate occasions (three bouts per occasion). Substrate oxidation was measured with indirect calorimetry and was calculated using stochiometric equations. In both, women and men the highest fat oxidation rate occurred at 65% VO2peak and this did not coincide with either the VT or LT. A significant correlation between VT and LT could not be found in women (r=0.33) nor men (r=0.277). In obese women and men training recommendation for maxim...

Is the highest fat oxidation rate coincident with the anaerobic threshold in obese women and men

Background The exercise intensity eliciting highest fat oxidation is important for a variety of populations and its precise determination requires an adequate exercise protocol. The aim of this study was to compare fat oxidation, concentration of lactate and lactate threshold during an established exercise protocol using fixed workloads with a protocol based upon the subject's individual heart rate response to exercise.

Materials and methods  Highest fat oxidation, concentration of lactate and lactate threshold were compared between two different exercise protocols in moderately trained men (n = 48) and women (n = 30). In randomized order subjects completed a standardized (STAND) and an individual (IND) submaximal exercise test. The increments during IND were adapted by the subjects’ individual heart rate response to exercise compared to STAND with defined steps.

Results  In men, fat oxidation was significantly higher at the intensity eliciting highest fat oxidation in STAND than in IND (P = 0·019), but not in women. In both genders lactate concentration (P < 0·001) and heart rate (HR) (P < 0·001) were significantly higher in IND compared to STAND at this intensity. A significant correlation between O2 at lactate threshold and the intensity eliciting the highest fat oxidation was found in both genders in IND (women r = 0·73; men r = 0·43) and in STAND (women r = 0·57; men r = 0·56).

Conclusion  Different exercise increments and stage durations have an influence on lactate concentration and HR at the intensity eliciting the highest fat oxidation. The shorter test duration of STAND favours this protocol to determine maximal fat oxidation. For the untrained, start of exercise should be at very low intensity.

Is the intensity of the highest fat oxidation at the lactate concentration of 2 mmol L−1? A comparison of two different exercise protocols

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Effects of an extreme endurance race on energy balance and body composition - a case study.

Is the highest fat oxidation rate coincident with the anaerobic threshold in obese women and men

Is the intensity of the highest fat oxidation at the lactate concentration of 2 mmol L−1? A comparison of two different exercise protocols