Gas Exchange Test Results, help interpretation

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  • #8074

    I am starting my third training cycle following TfTNA and decided to do a Gas Exchange Test (GET) to get a clearer picture about my AeT and metabolic efficiency.

    We did 5 minutes stages with 1 km/h speed increments.

    According to the test my Metabolic Efficiency Point “MEP” (RER = 0,85) occurs at a heart rate of around 127 bpm / speed 6,5 km/h (see MEP Graph.pdf).

    According to the same test my AeT is at a heart rate of 164 bpm / speed 9,2 km/h. That is when my lactates begin to rise (1.5 mmoI/L).

    Please see detailed results on Page 2 of attachment (Test Results.pdf) and the Lactate Graph on Page 3.

    According to the test my AnT is 193 bpm. I will disregard this and do the recommended DIY Anaerobic Threshold Test Outdoors

    So my questions:

    – What are my training zones?
    – Does the upper limit of my Z1 is at a heart rate of 164 bmp (Aet) or at 127 bmp (MEP)?
    – any other interpretations or suggestions based on my results?
    – Should I avoid Z2 training?

    In any case, it seems clear that I need to train my body to improve metabolic efficiency and burn more fats. As apparently my AeT is higher than my MET I hope I can do this by diet and training smarter (in a fasted state) as opposed to running at a painfully slow and potentially injuring 127 bmp / 6.5 km/hr. I would appreciate any feedback on this.

    My sincerest thanks and appreciation to the Uphill Athlete’s founders and community!


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    agc on #8077

    *Correction: According to the test my AnT is 183 bpm. (not 193) bpm

    Anonymous on #8082


    Good for you for taking the initiative to get into a lab and get a proper test to see what’s going on inside those muscles. Sometime the results are not what we expect. I have seen several tests like yours when the AeT (top of Z2) does not correspond with the cross over point (50-50, fat-carb use). This is actually good news for you. But you won’t like the fix too much.

    Having a high AeT HR/speed is an indicator that your muscles have a lot of capacity for doing aerobic work, even while consuming a high percentage of carbs for fuel. Your AeT (164) is only 11% below your AnT (183) so this is a reflection of that first sentence. This is the good news.
    If you want to train to continue to improve your AeT HR/pace then you need to train at and just below 164. With you low AnT/AeT ratio you should now start adding one Z3 workout/week as well.

    Now for the not so good news: If you want to improve you fat utilization and bring that cross over point (127) up to your AeT you have train at the intensities where you are using mainly fat. This means under 127. I hear your howls. This fat adaptation is pretty easy to modify and way faster to respond than is are the aerobic adaptations need to move the AeT up. If you are not doing so, start doing all aerobic runs in a fasted state. If you can work up to doing your long runs this way and not feeling energy loss during them you’ll know you have moved this the 50-50 point. If you are doing aerobic training volume in excess of 12 hours/week you’ll probably affect big changes in 2-4 weeks. Under 10 hours/week will take considerable longer. The biggest stimulus for aerobic adaptation is duration. So the more you do the faster the changes. I’d say do 75% of aerobic training below 127 and 25% near 164 for now.

    Some dietary shift to a higher fat lower carb will also speed the fat adaptation but in my experience it is training that really has the big effect. I work with some top athletes who do not eat high fat/low carb diets but are very fat adapted because they do 20+ hours of aerobic training a week.

    I hope this helps. Your will be very pleased with the results when you have moved that cross over point up to 164!


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