Hello, 

Depending on the parameter taking into account (VO2, heart rate, expressed as absolute value or as a percentage of maximal value), Crossover point and LIPOXmax are relatively related to ventilatory threshold (Michallet et al. Diabetes Metab 2008 ; Gmada et al. sic Sports 2013 ; Borel et al. MSSE 2015), .

Two of the best indices for fat oxidation rate are LIPOXmax and COP (crossover point). These two metabolic concepts can be theoretically determined based on an incremental exercise and then after, you have to perform a second test (sub maximal test this time) with four stages of 6 min at 30%, 40%, 50% and 60% of peak power output determined with the first incremental exercise, with a warm-up period at 20%. Then, based on CHO oxidation rate and lipid oxidation rate formulas which need VO2 and VCO2 during the different stages, you can then determine the time course of lipid oxidation rate and determine the maximal rate. 

You can find more information about this specific exercise protocol : Dumortier et al. Diabetes Metab 2003 and Dumortier et al. Int J Obes (London) 2005. 

This is some elements I can provide you on the questions you raise up. 

Best regards

Hello

First you need to understand how FATmax is an individual parameter and it will occur in every subject at different intensity. It ranges from 25% to 85% VO2max, depending from age, gender, activity type, fitness level and testing methods. So, this protocols where they try to determine FATmax at some fix intensity won't work and talk about how FAtmax is at some fix VO2max percentage is incorect. FATmax highly correlates with aerobic threshold or first lactate threshold in everybody and you can use it as a prediction parameter or training parameter for when FATmax occurs. 

Best exercise protocols to identify maximal fat oxidation rates in any subject are GXT short stage protocols (2 min) with small inclines (1%) and small speed rise (1 km/h). Depending of the subjects they can be sub- or maximal but what is important to have continues substrates oxidation measurement. 

Furthermore, oxidation rates are dependent from ergometer type, genetics, day time and nutrition so you need to keep that in mind.

Hope this answers your question.

Hello Ratko,

any reference of this protocol? How can we use it in cyclists?

Thanks

Manuel Ordiñana Pérez The thing with these protocols is that there is no universal consent among the researchers which one is the best. My personal opinion and experience suggest that when ever we examine the FATmax occurrence, we aim to define the exercise intensity (expressed in VO2) at which it occurs. Therefore, we need a protocol that will assure liner and valid VO2 rise with substrates utilization measurement being continues; we cant accurately determine FATmax if we only use several exercise intensities. Its confirmed that 1-3min stages are optimal for VO2max assessment with 25 to 50 watts load and ca 100 rpm/min in cyclists. Some scientist state that the test stages need to be prolonged to achieve substrates utilization steady state. But, if you go with the prolonged stages, then you have biased the VO2 accuracy and the intensity occurrence is not correct. Therefore, you should adjust the stage length according to the fitness level of your subjects because studies have confirmed connection between the time to utilization steady state and fitness and negligible difference in substrates utilization when 1-3 stages are compared. Top class athletes can have 1-2min stages, recreational people 2min stages and obese and sedentary 3min stages. That way you have stayed within the objective stage length for the proper VO2max assessment and allowed your subjects to achieve a substrates utilization steady state.

Hope it helps

Could be correct continuous protocol (7,5w each 15 seconds)? And why hight cadence of 100rpm? I think that this could be too high to ensure gradual intensity.

Manuel Ordiñana Pérez

If you have a 7,5W every 15 sec that is not continues but linear. If you go with linear, there is no time for substrates utilization steady state occurrence. Cadence above 100 (extremely high cadences) increase the metabolic cost of cycling influencing the substrates utilization (overestimates CHO and underestimates fat) in non top level athletes. Ideal cadence is influenced by the fitness status of the subjects. Lover the fitness, lover the cadence. It ranges from 60-100, depending of the subjects type. For obese and sedentary 60-70 is ok, Recreational 80-90, god recreational 100 and athletes 100 and above. Top level athletes go above 100-120.

If you go with 80-90 rpm for everybody but top level athletes, you wont be wrong.

I'w said 100 because you have asked my about athletes

Thanks for your answer, I understand your propose. It will be possible to propose a preferred cadence? For top level cyclist I see 100 or 120 rpm a too high cadence...

Hello!

We have recently published a systematic review (PMID: 30929281) studying methodological consideration related to MFO and Fatmax. It includes all papers that have assessed MFO including details about the MFO protocol. I think It could be useful for you.

BW

Francisco J. Amaro Gahete

Start low enough and stay at each level long enough to optimize substrate reaction to stress. There should be flexibility as to RPM for individual style of riding 80-100 rpm. We are preparing for a series of test's with our clients to define Metabolic Crossover and MFO. We will be experimenting with a variety of testing from 2' to 10' per level to firmly establish substrate steady state at a variety of duration's at same intensity. Purpose is to truly define the metabolic point at which each client crosses over metabolically from fat to carb as a percentage of Max Vo2 and Max Heart Rate for practical exercise prescription going forward. My guess we will find our clients crossover and much lower intensiies (%MHR) than we have ever predicted, thus the client has been missing a specific opportunity to target a list of Health Performance and Composition biomarkers.

Perfect protocol for identifying MFO for endurance athletes. This is my CPET last week.

Here you have the example of fat and CHO utilization and the point where they cross is crossover point

Any of you have a spreadsheet to calculate fatmax from the RER?

Carlos Abraham Herrera Amante Difficult to calculate FatMax just from RER using a spreadsheet. It's more trial and error as FatMax is so individualised.

Ideally you want to test the participant to find out their fat oxidation rates at different intensities.

Terun Desai finally I was build a spreadsheet. I share it with all of you. When comparing the data obtained from the respiratory quotient (RQ) table with the data obtained using the Péronnet and Massicotte equation, these were different for fats. Some of you have experience with this equation?