Just finished up some testing with these devices fyi:
| Device | Trials with sweat-loss data | Avg sweat-loss accuracy (%) | Trials with Na⁺ data | Avg Na⁺ accuracy (%) |
|---|---|---|---|---|
| HDrop | 10 | 91.7 | 10 | 92.8 |
| FlowBio | 10 | 68.4 | 10 | 54.6 |
| Nix | 8 | 69.3 | 8 | 75.6 |
Very surprised with the HDrop and reliability under the same conditions - (same intensity, all indoor, temp and humidity controlled). Been playing with it outside with different intensities and weather and there was definitely variation, but I think that comes into play with physiology itself. Recent studies are showcasing that sweat sodium excretion is not fixed, and it is more a ~400mg/L range depending on power/hr/intensity/weather…. So I guess more to come!
Full data table here
Flowbios Flowpatch - Sweat rate and sodium loss sensor - Equipment - TrainerRoad