Every question the Health Data pages answer
The 14 health data pages answer 70 named questions between them. Every one is listed below, and every link lands on the paragraph that answers it rather than the top of the page.
Heart Rate API: How to Get Heart-Rate Data Into Your App
- Is heart rate from a wearable measured or estimated?Heart rate itself is measured, not modeled. Most consumer devices read it optically with a PPG sensor (green or infrared LEDs at the wrist…
- How do I get real-time heart rate into an app?For live, in-workout HR, read on-device through a HealthKit workout session on iOS or Android Health Connect, or connect directly to a…
- Which data types expose heart rate on HealthKit and Health Connect?On Apple HealthKit, general samples come from `HKQuantityTypeIdentifierHeartRate`, with `HKQuantityTypeIdentifierRestingHeartRate`,…
- Can I get all-day and resting heart rate from Strava?No. Strava exposes heart rate only as a per-workout activity stream in BPM, not resting or continuous all-day HR. For resting HR and…
- Should I use an aggregator or integrate each wearable directly?Integrate directly when you support one or two sources or need on-device, low-latency reads; that keeps the data path simple. Use an…
HRV API: How to Get Heart Rate Variability Data
- Is HRV measured or estimated?The HRV value itself is measured from real beat-to-beat interval timing. What is not a direct measurement is the interpretation: RMSSD…
- What is the difference between RMSSD and SDNN in HRV APIs?They are two different statistics computed from the same interbeat intervals and are not directly comparable. Apple HealthKit stores SDNN;…
- Can I get HRV from a phone without a wearable?No. HRV needs a device that captures beat-to-beat intervals, so it requires a wearable (ring, watch, band) or a chest strap. A phone alone…
- Why do Oura and WHOOP HRV values differ from a morning app reading?Most consumer platforms compute HRV over a nocturnal/overnight window for comparability, while some apps use a guided morning spot reading.…
- Which API is best for HRV?For recovery or readiness scoring out of the box, Oura or WHOOP, which bake nightly HRV into their models. For a raw RMSSD trend on…
VO2 Max API: How to Get VO2 Max Data
- Is VO2 max from a watch accurate?Consumer VO2 max is an estimate, not a lab measurement, so treat it as a fitness-trend signal rather than a precise value. Accuracy varies…
- Which APIs expose VO2 max data?Apple HealthKit exposes HKQuantityTypeIdentifierVO2Max on-device, Android Health Connect exposes Vo2MaxRecord, and cloud wearable APIs…
- Is consumer VO2 max measured or estimated?Estimated on every consumer device. True VO2 max comes from a lab graded-exercise test with a metabolic cart. Watches and rings model it…
- Can I compare VO2 max across Garmin, Fitbit, and Apple?Not directly. Vendors label it differently (VO2 max, Cardio Fitness Score, Cardio Fitness) and use different estimation models, so the same…
- How do I read VO2 max in an iOS or Android app?On iOS, request permission and read HKQuantityTypeIdentifierVO2Max from HealthKit on-device; there is no Apple cloud pull. On Android, read…
Blood Oxygen (SpO2) API: How to Get SpO2 Data
- Is consumer SpO2 data a medical measurement?No. SpO2 is genuinely measured by an optical sensor, but consumer wearables and rings are marketed as general fitness and wellness devices…
- Which platform data types expose blood oxygen?On iOS, Apple HealthKit exposes HKQuantityTypeIdentifierOxygenSaturation as an on-device permissioned read. On Android, Health Connect…
- Can I get an Apple Watch blood oxygen reading in the US?It depends and is unsettled. Apple Watch's Blood Oxygen feature was disabled on new US units after a 2023 ITC order, then restored around…
- Do wearables give continuous SpO2 or just overnight readings?Both modes exist, but they differ by source. On-demand spot readings require the user to initiate and hold still; overnight or background…
- What is the easiest way to read SpO2 across many devices?Use an aggregator such as Terra, Junction, or Rook, which normalize SpO2 across providers behind one schema and webhooks where the…
Sleep Tracking API: How to Get Sleep Data Into Your App
- Are sleep stages from a wearable accurate?Sleep stages (light, deep, REM, awake) are estimated from movement, heart rate, HRV, and respiration, not from EEG, so they are modeled…
- Can I get sleep data from a phone without a wearable?Typically not reliably. Phones alone usually do not produce trustworthy staged sleep, so phone-only sleep should be treated as coarse.…
- Why do sleep stages differ between Oura, WHOOP, and Apple?Vendors use different stage taxonomies. Apple uses Core, Deep, REM, and Awake; others use Light, Deep, REM; WHOOP uses Light, REM, and…
- How do I access sleep data on iOS and Android?On iOS, read HealthKit's HKCategoryTypeIdentifierSleepAnalysis on-device with the user's permission. On Android, read Health Connect's…
- Can sleep tracking APIs diagnose sleep disorders?No. Consumer sleep data is a general wellness signal, not a medical diagnostic. Stages are estimates validated only imperfectly against…
Step Counting API: How to Get Step Data
- Can a phone count steps without a wearable?Yes. Step counting is one of the few fitness metrics fully available from a phone alone - its accelerometer feeds a pedometer. On iOS you…
- Why do my step counts look doubled?Because a phone and a paired watch both log steps, so naively summing every source roughly doubles the total. Use the platform's…
- Are step counts measured or estimated?They are counted, but algorithmically - motion-sensor pattern recognition interpreting accelerometer data, not a sensor that registers each…
- Did Health Connect change how steps are attributed in 2026?There is a reported 2026 change to on-device step attribution in Health Connect - legacy readings attributed to the "android" package…
- Which source should I use for step data?For the widest reach with least friction, read the on-device platform store (HealthKit on iOS, Health Connect on Android) so you inherit…
Workout Detection API: Get Recorded Workout Sessions
- Which providers auto-detect workouts vs. require a manual start?Fitbit SmartTrack auto-recognizes select activities after sustained movement and logs them with no manual start, while Apple Watch…
- How do I read workout sessions on iOS and Android?On iOS, read Apple HealthKit's HKWorkout on-device with per-type permission; each session carries an activity type plus fields like…
- Is a detected workout type accurate?The session's duration is measured, but the activity type and session boundaries are algorithmically inferred, especially for auto-detected…
- Is this the same as AI camera-based rep counting?No. This page covers recorded workout sessions from HealthKit, Health Connect, Strava, and Garmin. AI camera-based rep or exercise…
- How do I merge workouts from different sources?Activity-type taxonomies differ across HealthKit, Health Connect, Strava, and Garmin, so their type enums are not a 1:1 mapping. If you…
GPS Activity API: How to Get Route Data from Workouts
- Is GPS route data measured or estimated?The coordinates are measured by the device's GNSS/GPS receiver, not modeled. But the measurement is noisy: it drifts near buildings or tree…
- Can I get GPS route data from a phone without a wearable?Yes. A phone has GPS, so it can record a route on its own, and a GPS-capable watch or bike computer can too. A non-GPS wearable relies on…
- What are Strava's API restrictions for route data?Strava enforces rate limits and has been tightening access; for example the Explore Segments endpoint is documented as moving to an…
- Which API is best for GPS route data?To show a user their own route, the on-device path is least restrictive: HKWorkoutRoute on iOS, ExerciseRoute on Android. To pull routes…
- How do HealthKit and Health Connect expose route data?On iOS, HealthKit stores a route as HKWorkoutRoute attached to a workout; you read it with HKWorkoutRouteQuery and build it with…
Calorie Tracking API: How to Get Calorie Data
- Are calories burned measured or estimated?Estimated. Calories burned is a model derived from heart rate, motion, activity type, and your profile (age, weight, sex) via a proprietary…
- How do I get calories consumed from a fitness API?You do not get intake from a wearable or phone sensor, because nothing measures what a person eats. Calories consumed comes from food…
- What is the difference between active and total calories?Active energy is exercise/movement calories only; total energy includes basal (resting) energy on top. On HealthKit, activeEnergyBurned and…
- Why do calorie counts differ between my devices?Because they are estimates, not measurements. Each vendor uses a different proprietary model over heart rate, motion, and user profile, so…
- Which API is best for calorie tracking?For calories burned with the widest coverage, read the on-device platform energy types (active plus basal on HealthKit, active plus total…
Body Composition API: Weight, Body Fat, and Lean Mass Data
- Can a fitness watch or band measure body fat?No. A typical wrist wearable does not measure body fat, lean mass, or BMI. Those come from a smart scale using bioelectrical impedance, a…
- Is body fat percentage from a smart scale accurate?It is an estimate, not a lab measurement. Consumer scales use bioelectrical impedance analysis (BIA), which infers fat versus fat-free mass…
- How do I get weight and body fat data from HealthKit and Health Connect?Apple HealthKit exposes bodyMass, bodyFatPercentage, bodyMassIndex, and leanBodyMass as on-device quantity types you read with per-type…
- Is BMI measured or calculated?BMI is calculated, not measured. It is weight divided by height squared, so it is only as good as the weight and height behind it.…
- Which API is best for body composition?For a full breakdown of fat, muscle, water, and bone, integrate a smart-scale source; Withings is the common pick for a rich bioimpedance…
Menstrual Cycle API: How to Get Cycle Tracking Data
- Which Health Connect records cover menstrual cycle tracking?Health Connect groups them under Cycle Tracking: MenstruationFlowRecord (instantaneous, with a flow field taking FLOW_LIGHT, FLOW_MEDIUM,…
- Does Apple HealthKit predict ovulation, or only store what was logged?HealthKit stores samples; the prediction lives in Apple's Cycle Tracking feature, not in a type you read. Apple documents that Cycle…
- Can a wearable detect a period automatically, or must the user log it?Flow, spotting, cervical mucus quality, ovulation test results, and sexual activity are all logged by the person or written by another app;…
- What extra privacy obligations come with period-tracking data?Treat it as the most exposed category in consumer health. Google's Health Connect guidance is to request only the permissions and data…
- Which wearable cloud APIs return menstrual cycle data?Fewer than you would expect. Among the sources documented on our pages, Terra is the one that normalizes cycle data, with a menstruation…
Blood Glucose API: How to Get Glucose Data Into Your App
- Where does blood glucose data in HealthKit and Health Connect come from?Almost never from a fitness wearable. It comes from a fingerstick meter or a continuous glucose monitor, hardware sold and regulated as a…
- What units do blood glucose samples use, and how do I avoid a unit mix-up?Apple documents that blood glucose samples may be measured in mg/dL (milligrams per deciliter) or mmol/L (millimoles per liter) depending…
- Can I read continuous glucose monitor data through a fitness API?Usually indirectly. On a phone you read whatever the CGM's companion app wrote into HealthKit or Health Connect. Server-side, our pages…
- Is a glucose reading measured or estimated?Measured, not modeled - but glucose names several different measurements that are not interchangeable. Health Connect makes this explicit…
- What must a wellness app avoid claiming about glucose readings?Do not compute or display dosing suggestions, do not frame alerts as clinical instructions, and do not describe your app as monitoring or…
Blood Pressure API: How to Read BP Data In Your App
- Which platform data types store a blood pressure reading?Apple HealthKit uses two quantity sample types, HKQuantityTypeIdentifier.bloodPressureSystolic and…
- Why does HealthKit want systolic and diastolic combined into a correlation?Because on iOS the two halves are separate sample types, and only the correlation ties them together as one reading. Apple documents…
- Does Health Connect require body position and cuff site for BP?Yes. BloodPressureRecord lists systolic, diastolic, bodyPosition, measurementLocation, metadata, and time as mandatory fields. The…
- Can a smartwatch send blood pressure into my app without a cuff?Our pages document no consumer wrist wearable that measures blood pressure, so this is a claim to verify with the vendor rather than…
- Why do Health Connect blood pressure writes throw an exception?The record validates ranges and throws IllegalArgumentException when a value falls outside them. Health Connect documents systolic as valid…
Respiratory Rate API: How to Get Breathing-Rate Data
- What unit does respiratory rate use on HealthKit versus Health Connect?Health Connect fixes it: RespiratoryRateRecord exposes rate as a Double documented as respiratory rate in breaths per minute, with a valid…
- Does the API tell me how a breathing-rate value was produced?No. Neither platform type carries a method or source field. Health Connect's record holds only rate, time, and metadata, and Apple's is a…
- Can Health Connect compute a nightly average respiratory rate?Not for you. The Health Connect data types page lists aggregate metrics for several vitals, such as systolic and diastolic averages for…
- Which wearable APIs return a breathing rate field?On our pages, Oura API v2 returns respiratory rate as part of its sleep payload alongside sleep stages and HRV, and Fitbit's documented…
- Does an Apple Watch record breathing rate on its own?Apple's documentation for the respiratory rate quantity type states that the system automatically records samples on Apple Watch. Your app…
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