Two workouts of the same length can have very different hydration demands. Temperature, intensity, clothing, and the individual all matter. Sweat testing is most useful when it helps you prepare for the conditions you actually train and race in.

hDrop Gen2 is a reusable wearable designed to provide exercise sweat information through its app. Within a performance assessment, it connects sweat and sodium-loss estimates with the conditions of your workout, helping turn the results into a practical hydration discussion.

What the numbers mean

hDrop markets estimates of sweat rate and sodium loss. Sweat rate describes fluid lost over time; sodium concentration describes sodium per volume of sweat; total sodium loss depends on both concentration and fluid loss.

These are not interchangeable with blood sodium, a clinical laboratory sweat test, or a diagnosis of dehydration. A sensor samples at a body site and uses its measurement system to produce estimates; it does not collect and measure every drop from your whole body.

Start with a representative session

Choose an ordinary workout relevant to your goal, such as a familiar ride in expected race conditions. Do not deliberately overheat yourself or withhold drinks to create a “better” test.

Record the activity, duration, approximate temperature and humidity, indoor or outdoor setting, intensity, and what you drink. Start normally hydrated and follow any medical fluid or sodium advice you have already been given. If a health condition affects fluid or electrolyte management, discuss changes with your clinician rather than letting a fitness app override that plan.

Set up and wear hDrop Gen2

  1. Charge and inspect. The official setup guide says charging wakes the device for its first use. Check the sensor, strap, and charging-port protection, and follow the supplied instructions before exercise.
  2. Set up the hDrop app. Install the official app, complete the account/profile steps, and connect the device through the app’s setup process. Confirm profile details and connection status, and check for firmware updates before the session, not halfway through it.
  3. Complete the initial thumb test. When prompted, cover the blue and black electrode surface with your thumb and hold still for about 30 seconds, following the app. This setup check is not a replacement for a workout measurement or proof of clinical accuracy.
  4. Fit the strap. The manufacturer’s Gen2 setup guide specifies the upper arm, with the sensor facing inward in direct contact with the skin. Use the appropriate supplied strap and adjust it securely without uncomfortable pressure. Prepare the skin as directed and avoid interfering with contact.
  5. Start the activity in the app. Select the appropriate activity option and begin recording. The guide says tracking starts once sweat reaches the sensor. An early absence of readings is not proof that you are losing no fluid; check contact and follow troubleshooting guidance if data remain missing.
  6. Finish and review. End the activity, upload/sync the session as directed, and review it in the activity log. Confirm it covers the intended workout and note any gaps before drawing conclusions.

The official setup page describes some live sweat and sodium totals as “coming soon,” while other product pages advertise real-time losses. Treat the exact live display and export fields as app-version dependent until verified on the actual device. A post-session review is more useful than promising a feature that has not been checked.

Turn the result into something you can use

First check the units. A rate in milliliters per hour is different from a total in milliliters, and sodium in milligrams is different from grams of table salt. Read whether the app reports a concentration, rate, or accumulated total.

For illustration only, a sweat rate of 0.8 liters per hour and a sodium concentration of 700 milligrams per liter would imply an estimated sodium loss of 560 milligrams per hour. That arithmetic is not a prescription to consume that amount, or to replace all sweat loss immediately.

Build a practical plan around session length, thirst, access to drinks, food, comfort, and the conditions. Test changes in training and pay attention to gastrointestinal tolerance. Do not force large volumes of fluid to match an app: overdrinking can be dangerous, and adding sodium does not make overdrinking safe.

Repeat under relevant conditions before treating a result as typical. A cool easy ride is not a permanent forecast for a hot race. Keep the sensor placement and recording procedure consistent so changes in setup do not masquerade as changes in your sweat response.

Clean, store, and protect the record

The official Gen2 setup guide recommends gently wiping the electrodes with the included alcohol prep pads after use, avoiding scratches, and storing the device in its protective case. Follow the supplied instructions for the actual unit; do not assume it can be submerged or used while swimming. Keep the charging area dry as directed before charging.

Review sharing and export settings, especially if an assessment involves a coach. Share only the intended session and keep health-related records out of public training posts unless you deliberately choose otherwise.

How it fits the service

At GradientPeak, sweat assessment is an optional addition within Performance Assessment, with availability and scope confirmed before booking. The service reviews the hDrop session alongside the weather, intensity, duration, and drinks you recorded. The consolidated report and results discussion turn those observations into a hydration approach to practice in training, with adjustments for comfort and the demands of your event.

The device is not a safety monitor for heat illness. Stop exercising and seek appropriate help for concerning symptoms rather than waiting for an app alert.

Manufacturer references

Manufacturer web information reviewed October 26, 2026. Verify the current app, firmware, and supplied instructions before use.