Choosing a fitness tracker

How do you choose the right fitness tracker?

Choose on comfort and ease of use before extra features¹. How a device looks and how easy it is to use are the main reasons people give for liking or disliking one⁴. Check these things before you buy:

• Screen: look for a large, easy-to-read screen with a simple display. Small text can be hard to read as eyesight changes¹.
• Buttons: they should be easy to press, in both size and the pressure needed. Touchscreens can be especially hard to use, so test one carefully¹.
• Comfort: the strap shouldn't irritate your skin, the device shouldn't be too big or too small, and it should be easy to put on and take off without fiddly clasps¹.
• Battery: choose battery life you can manage. A display that warns you when the battery is low can help you remember to charge it¹.

If you have limited sight or grip strength, you may need different features from those on a standard tracker¹.

It helps to know what a tracker can and can't do. Wearing one is linked with roughly 1,800 extra steps a day². Effects on blood pressure, cholesterol and blood sugar tend to be small, so don't expect a tracker alone to improve them². Step counts are approximate and can differ from one device to another³.

Before you buy, hold and wear the tracker if you can. Ask a family member, friend or the seller to help with set-up, and buy only from a shop or seller you trust.

What do fitness trackers measure?

Typical consumer trackers estimate steps, active time, idle time, calories burned and sleep^5,6. They are estimates, not exact measures, and some are more dependable than others.

• Steps: these are the most dependable number a tracker gives, and step counts tend to be close to reference counts in laboratory tests, particularly on a treadmill⁸. They are still approximate. Counts from different trackers can differ by 20% or more, and some devices may miss steps at very slow walking speeds⁷. Results vary by device, user and setting, so no single device's numbers should be taken as exact³.
• Active time: along with steps, this is a sensible main number to follow.
• Calories: these are the least trustworthy output. None of the wrist trackers tested proved accurate for calories⁹, and agreement on activity calories was lower than agreement on steps in older adults¹⁰. Don't plan your eating around the calorie figure.
• Sleep: trackers generally over-estimate how long you sleep^8,3. Don't read much into the detail.
• Scores: scores such as "body battery" or readiness haven't been formally validated, so don't rely on them as health measures³.

Use steps and active time as your main numbers. Look at your own pattern over days and weeks rather than any single day's figure.

When to check with a health professional

If you're starting exercise after a long break, it's always a good idea to see your doctor first. For an injury or a health condition, see a health professional, such as your doctor or a physio.

A tracker can't diagnose a medical condition. If something worries you, see a doctor rather than relying on a tracker's numbers. For a sore muscle or joint, ease off, and see a doctor or other health professional if it persists or gets worse.

Call your local emergency number for chest pain or pressure (or pain spreading to the arm, neck, jaw or back, especially with sweating or feeling sick), severe breathlessness, fainting or collapse, signs of a stroke, a serious injury, or someone who isn't safe.