Scott Ferguson (PhD Physiology) is wrapping up an article on Threshold Confusion. So, stand by!
Also, I am am just putting the finishing touches on a 4 part article series on testing to determine you metabolic response to exercise and what/why I recommend. Let me summarize some of that here:
1)Gold Standard Test: Gas Exchange Test done by a competent lab. Uses expired gases to determine fat/vs carb ratio at various intensities, AeT and Ant/Lactate Threshold (LT) and finally VO2max.
The RER, Respiratory Exchange Ratio is used to determine these metabolic thresholds. Many labs combine this test with a blood lactate test as confirmation.
2) Blood lactate test. Silver Standard. By far the simplest and cheapest accurate way to find AeT. Not so useful for AnT and I recommend an field test as explained elsewhere on this site.
3) Ventilation markers. I have used these for 20+ years to test athletes with a good endurance training history up to an including at the Olympic level. Nose breathing correlates 95% with AeT in this population. However, since starting to work with folks who do not have a good endurance training background in the past 3 years, I have found many cases (as mentioned in the above posts) where there was very poor/no correlation. In fact; the worse the aerobic deficiency, the less ventilation correlation I see. I have asked several exercise physiologists “why”? but so far no one knows.
So, in cases where ADS (aerobic deficiency syndrome) is obvious or likely I strongly recommend a real test and not relying on a ventilation test or simple % of maxHR formula.
It is the real metabolic events of AeT and AnT/LT that must form the anchor points for any accurate training zone system. Without knowledge of these points you are guessing. A lactate test is very good way to do this. It is relatively cheap, can be done in the field using sport specific means and when administered well can show most of what you will get in the gas exchange test. These tests can be repeated during the training cycle to show changes in the metabolic response and hence training effect.
The BSX Insight and MOXY work by measuring O2 sat in the working muscles and then relating that to intensity. Both these products originally promised to give real time lactate readings by using an algorithm that correlated O2 Sat to lactate. But the algorithms could not and to my knowledge still can’t provide a good correlation. The technology is promising and the SmO2 is probably very accurate but just because we can measure a quantity does not mean we know how that quantity relates to something else we are interested in knowing about. I have tried both devices and was disappointed with their correlation to any of the well tested methods of gas exchange tests or lactate tests or field test. I don’t recommend their use to any of the athletes I work with. The tests mentioned above will provide all the info needed and do it in a way you can directly transfer to your training.