Why Everyday Athletes Are Testing Their Sweat (and Why It's MostlyPointless)

We may earn a commission from links on this page. TrainingPeaks—the training-log app plenty of serious runners, cyclists, and triathletes live in—recently rolled out a direct integration with hDrop , a reusable wearable sweat sensor. The idea is that athletes wear it on their arm, and sweat loss and sodium loss data get logged alongside their workout notes, right next to heart rate and power. The integration lets hDrop users sync hydration metrics like sweat loss, sodium loss, and hydration behavior directly into TrainingPeaks, becoming part of the same decision-making metrics as heart rate or pace. At charging $249.99 for its wearable hydration sensor, hDrop isn't alone. Two other big names in wearable sweat sensors are Nix (around $189) and FlowBio (around $340). On the budget end, Gatorade sells single-use sweat tests for around $25. The goal of all these sweat testing wearables is to tell you exactly how much fluid and sodium you're losing on a run or ride. As a marathon runner myself, it's easy to see the appeal of these products. After all, in an actual lab, sweat testing can be used to guide personalized fluid and electrolyte replacement recommendations for serious athletes. These consumer sweat sensors are chasing the same promise, just without the lab settings. Unfortunately, as multiple studies have pointed out, it's tough to achieve lab-level accuracy out in the field. Let's take a look at why you most likely do not need to waste your time and money on …