Apple Watch and Osteoarthritis: What Walking Data Shows

Your knee complains on the stairs, and the Health app now shows a number called walking asymmetry. The short answer first: neither the Apple Watch nor the iPhone can tell you that you have osteoarthritis. They estimate how you walk. You can log joint pain on paper or in Sam's symptom diary; walking metrics you switch on from Apple Health then sit in the same app, a few taps away. Below: which device measures what, what the numbers mean and when a fall cannot wait.

Can an Apple Watch tell you that you have osteoarthritis?

No. The watch and the iPhone use motion sensors to estimate how you walk. Apple calls these Mobility metrics estimates that characterize your gait and mobility. It describes no feature that assesses joints or identifies osteoarthritis.

Osteoarthritis is identified by a doctor. The NICE guideline NG226 tells clinicians to diagnose it clinically in people aged 45 or over with typical symptoms. Imaging is not to be used routinely. The NHS says the same in plainer words: a GP asks about your symptoms and examines your joints. Data from phones or watches does not appear in the NICE recommendations.

So an unusual walking reading does not prove osteoarthritis, and a typical one is no all-clear. How to write down pain, stiffness and flares for your appointment is covered in the osteoarthritis pain diary. Who to see, how it is diagnosed and what X-rays and blood tests show is in what doctor treats osteoarthritis. What Sam keeps for this condition is on the osteoarthritis page.

Does the watch or the iPhone measure your walking?

Mostly the iPhone. Apple's developer documentation says an iPhone 8 or later records these metrics itself.

In the Health app you find them under Browse, then Mobility.

For the iPhone to record them, carry it near your waist, such as in a trouser pocket, and walk steadily on flat ground. Keep your height up to date in the Health app, because the model depends on leg length. Running or walking uphill produces no readings. Nor does Wheelchair mode. If you mostly carry the phone in your hand, a backpack or a bag, you get fewer readings, Apple notes.

The watch contributes the six-minute walk estimate. Both devices count steps and flights climbed. What else the watch measures is in the Apple Watch health sensors overview.

What is walking asymmetry, and what is normal?

Walking asymmetry is the percentage of time your steps with one foot are faster or slower than with the other. That is Apple's definition. Zero percent means every step in a walking bout was even. 100 percent means every step was uneven.

Apple also explains where asymmetry comes from. One side is injured or affected by a condition, and you lean on the other leg while walking. The number does not tell you what the cause is.

Apple gives no normal range for walking asymmetry. Its white paper says the metric does not classify severity; it only reports a share of time. Because few study participants walked unevenly, Apple induced asymmetry to develop the metric, with a locked knee brace in younger, healthy adults. Apple adds that brace-induced asymmetry could differ substantially from asymmetry caused by, for example, a neurodegenerative disease or a prosthesis.

This is not a test to run on yourself. A low number is no all-clear, and a high one is not a finding. If walking hurts, raise it with your doctor, whatever the number says.

How accurate are the iPhone gait estimates?

Apple checked the metrics against a pressure-sensing walkway. In the larger study group, older adults averaged almost 75 years, and Apple lists osteoarthritis for about half of them. The study measured how well the iPhone captures walking. It did not test whether the readings can identify osteoarthritis.

An independent Heidelberg team tested the Health app against a sensor system (Werner and colleagues, Scientific Reports 2023). Participants did a six-minute walk test. Walking speed and step length agreed well in adults and older adults. Double support time agreed only poorly to moderately in every age group. The study did not test walking asymmetry.

Apple writes that the metrics still need validation in more specific groups. It sees their value in tracking over longer periods, alongside clinical function tests and questionnaires. So one reading says little. Even a trend depends on where you carry the phone.

Walking steadiness low: what does it mean?

Walking Steadiness also comes from the iPhone, not the watch. Apple says the Health app assesses your balance, strength and gait when you carry the phone near your waist. It classifies the result as OK, Low or Very Low. Apple presents the feature as insight into fall risk.

If you opt in, the Health app sends a notification when your steadiness becomes low or stays low. It can also show exercises for walking steadiness. You set this up in the Health app under Health Checklist.

You can raise a low rating with your GP or primary care doctor; the rating alone does not replace an examination. The NHS advises seeing a GP if you are worried about your balance or mobility, or if you have had a fall. The GP checks your balance, for example by asking you to get up and move around. The GP may refer you to a falls service, which can check for muscle weakness, weak bones or eyesight problems and review your medicines.

Fall Detection is a separate Apple Watch feature. How it works is covered in Apple Watch fall and crash detection. After a fall with pain or injury, the last section of this article applies.

What does the Apple Watch six-minute walk estimate?

In a clinic, the six-minute walk test is supervised. You walk up and down a corridor of known length for six minutes, and the distance is recorded. For hip and knee osteoarthritis, the research society OARSI lists it among five recommended function tests. The others are the 30-second chair stand, a fast-paced 40-metre walk, a stair climb and the timed up-and-go test.

The Apple Watch does not run this test. From Series 3 on, it estimates once a week how far you would walk in one. It uses your movement over the previous four weeks. It needs at least three days with more than eight hours of wear in the past week. Over four weeks, it needs ten such days.

Apple caps the estimate at 500 metres, and results are best when your expected distance is below that. Apple developed the estimate with adults aged 65 and over. A weekly estimate does not replace a supervised test. Which tests your physiotherapist uses is up to them.

Where do the walking metrics appear in Sam?

Sam reads these values from Apple Health and writes nothing back. By default you see Daily Steps, Active Energy, Exercise Time and Flights Climbed under Movement & Activity. The walking metrics sit in the Walking Stability group. It is off by default; you switch it on under Customize Metrics.

Sam then shows six rows: Walking Steadiness, Walking Speed, Step Length, Walking Asymmetry, Double Support Time and Six-Minute Walk. Each row shows the latest reading and when it was measured. Tap it to see the chart and statistics such as average, minimum and maximum. Below them, a generated text under What This Means may compare the latest reading with your earlier readings. It is general guidance, not a finding about your gait or joints. Walking Steadiness carries Apple's OK, Low or Very Low label. Sam shows the other five without a coloured rating.

Joint pain, morning stiffness and swelling go into the symptom diary, once per day, as mild, moderate or severe. The walking metrics are in the same app, a few taps away, but not next to those entries. The monthly report, which you create yourself once its requirements are met, covers symptom days and activity, not walking metrics. Sam does not pass on the Health app's steadiness notifications and sends no notifications about your gait. Paper or app for your log is compared in symptom diary: paper template or app.

When do you need help straight away after a fall or with joint pain?

Whatever your phone or watch shows, these tiers stay the same. Your symptoms decide.

• Go to the emergency department straight away or call your local emergency number (112 in the EU, 999 in the UK, 911 in the US): very bad joint pain after a fall or injury, or a joint that has moved out of place. The same goes for tingling or numbness around an injured joint, or not being able to walk or put weight on a joint. It also applies if a fall may have injured the head, back, neck or hip, or someone cannot get up.
• Get urgent help from a doctor or an urgent-care service: sudden severe pain and swelling in one joint, a red or hot joint, or joint pain with a fever, chills or feeling generally unwell. The same goes for a fall that leaves you in pain or unwell. In the UK that means an urgent GP appointment or NHS 111.
• See a GP: joint pain stops you doing normal activities or affects your sleep, pain or swelling is getting worse or keeps coming back, or your joints are stiff for more than 30 minutes after waking. The same goes if you are worried about your balance or mobility, or have had a fall. That is how the NHS puts it.

With the emergency signs, do not wait for them to pass. Sam is not built for this: it replaces neither an emergency call nor an examination.

Log joint days and see walking metrics in one app with Sam

You have your joint days and walking trend in one app, without hunting for screenshots.

• Instead of screenshots from the Health app: once you turn on the Walking Stability group, Sam charts walking speed, step length, walking asymmetry and the six-minute walk.
• Instead of loose notes: joint pain, morning stiffness and swelling get one entry per day, mild, moderate or severe. A joint can be its own symptom, such as "Left knee".
• Instead of counting the night before: the monthly report, which you create yourself, puts your symptom days on a calendar with your five most logged symptoms, as a PDF.

The walking metrics are device estimates, not in the monthly report or next to your entries. The generated text under What This Means is not a finding about your gait or joints. More on the osteoarthritis page.

Try Sam for free

Sam is a wellness companion, not a medical device. The app does not diagnose, treat, cure or prevent any condition or health state. Always consult qualified professionals for medical decisions.

Related reading

• Osteoarthritis pain diary: what to write down
• What doctor treats osteoarthritis? Diagnosis and tests
• Apple Watch 2026 health sensors: what every metric measures
• Apple Watch fall and crash detection
• Symptom diary: paper template or app?

Sources

Updated: October 2026

• Apple: Measuring Walking Quality Through iPhone Mobility Metrics (PDF) (May 2022)
• Apple: Using Apple Watch to Estimate Six-Minute Walk Distance (PDF) (May 2021)
• Apple Developer, HealthKit documentation: walking asymmetry, walking speed, step length, double support, Walking Steadiness and six-minute walk
• Apple Support: Monitor your walking steadiness in Health on iPhone (iPhone User Guide)
• Apple Newsroom: Apple advances personal health by introducing secure sharing and new insights (7 June 2021)
• Werner C et al.: Validity and reliability of the Apple Health app on iPhone for measuring gait parameters in children, adults, and seniors. Sci Rep 2023;13:5350
• Dobson F et al.: OARSI recommended performance-based tests to assess physical function in people diagnosed with hip or knee osteoarthritis. Osteoarthritis Cartilage 2013;21:1042-1052 (abstract)
• NICE: Osteoarthritis in over 16s: diagnosis and management (NG226), Recommendations (2022)
• NHS: Osteoarthritis (reviewed 20 March 2023)
• NHS: Falls (reviewed 6 March 2025), Joint pain (reviewed 26 February 2026) and Septic arthritis (reviewed 3 September 2026)
• NHS 111 Wales: Septic arthritis (updated 18 December 2024)
• British Society for Rheumatology: Guideline for the management of the hot swollen joint in adults with a particular focus on septic arthritis. J Antimicrob Chemother 2006;58:492-493 (summary)