This Lumen device in FB advertisements, useful or junk

Triathlon Forum
1

Not for losing weight but maybe as a method to determine or train in LT1.

It claims to monitor your co2 output to approximate the fat carb ratio. This seems like something you could possibly use during workouts to determine or stay honest in the zones. Isn’t that what lab ergonomic riding tests do with a mask?

I am notorious about riding too hard of easy workouts as they feel easy early then hard later because I can’t get in these 4+ hour rides others do. So have a habit of riding 2 hours at more.

Useless garbage or maybe some small potential?

2

I’ve seen this device and I don’t know if it will be good enough to use during workouts. It’s cheap enough to try though.
Here’s the validation study.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8167606/

Figure 3 leads me to believe the device provides false precision, something that is very easy to sell and very popular with people these days.