Wearable Readiness Scores Are Not Medical Advice

A readiness score is marketed as a daily answer to a tempting question: “How hard should I push today?” Different brands use different names and ingredients. Oura says its Readiness Score uses nine contributors compared with your personal averages; Garmin lists sleep, recovery time, heart-rate variability, training load and recent stress among its Training Readiness inputs. That makes the number a calculated estimate, not a direct measurement of “readiness.” The FDA’s January 2026 general-wellness guidance is useful here. It gives a wrist-worn product that assesses activity and recovery as an example of a low-risk general-wellness product when its claims stay outside medical or clinical use. In plain English, a wellness score may help you reflect on habits or trends, but it is not automatically a diagnostic test. The fair verdict is: useful signal, wrong authority. A readiness score cannot by itself diagnose an infection, explain fatigue, clear you for strenuous exercise or tell you to change medication or blood-pressure care. Some wearables do include FDA-cleared medical functions, but clearance applies to a specific function and intended use. It does not make every score, alert or coaching message in the app medical advice.

The evidence supports cautious use of the underlying measurements, not broad conclusions from one composite score. Consumer wearables can measure some signals reasonably well in some settings, yet performance varies by device, activity and outcome. A 2024 umbrella review of systematic reviews found that accuracy across common wearable health measures remained variable. A separate meta-analysis found meaningful differences between consumer wrist-worn sleep estimates and polysomnography, the clinical reference test. Research on heart-rate variability also identifies uncertainty from data collection, physiology and computational choices. That matters because several causes can move the same inputs. Poor sleep, a demanding workout, stress, alcohol, travel, illness or a change in how the device is worn may affect one or more measurements. Optical wrist sensors are also vulnerable to motion and contact-related artifacts. A lower score can coincide with one of these factors, but coincidence is not proof of cause. A higher score only means the algorithm saw a pattern it rated favorably; it does not rule out illness or another problem. If you use a GLP-1 medication, keep that distinction clear. MedlinePlus lists nausea, vomiting and diarrhea among semaglutide side effects and notes that trouble drinking fluids can cause dehydration. Those issues may change how you feel and may influence wearable signals, but the score cannot tell whether medication, illness, food intake, hydration or something else caused the change.

Readiness marketing works because it turns messy biology into one clean number. Color zones, trend arrows and labels such as “ready for challenges” feel decisive. Personal baselines add another layer of credibility: the result looks tailored to you, even though the algorithm still lacks your physical exam, full medical history, laboratory results and the context behind today’s symptoms. The FTC’s health-products guidance says marketers are responsible for both express claims and messages that consumers reasonably infer. Objective health claims need competent and reliable scientific evidence, and the evidence must fit the specific product and claim. That last point is easy to miss. A study showing that a sensor estimates heart rate reasonably well does not, by itself, prove that a composite readiness score can identify illness, prevent injury or safely prescribe workout intensity. Evidence for one model, firmware version or population may not transfer to another. Regulatory language can also create a halo. “FDA registered” is not the same as FDA approved, cleared or authorized, and a clearance for one function does not validate unrelated wellness features. Before paying for a device or subscription, look past testimonials and medical-looking graphics. Ask what was tested, against what reference, in whom, and whether the advertised promise matches the study’s actual outcome.

Use readiness as a trend and a conversation starter, not as a permission slip. Start by checking several days of data and the underlying measurements rather than reacting to one morning’s score. Note what changed: sleep, travel, alcohol, illness, workout load, device fit, charging gaps, food or fluid intake, and any symptoms. This record may make a conversation with your clinician more useful. Then match the question to the right tool. For blood pressure, the American Heart Association recommends a validated automatic upper-arm cuff with the correct cuff size; home monitoring does not replace clinician care, and you should not stop blood-pressure medication based on home readings alone. For any wearable medical claim, search the FDA’s Devices@FDA database for the exact product and read its intended use. Do not assume a cleared ECG or notification feature also clears the readiness score. Check the company’s current evidence, limitations, privacy terms, data-sharing practices, deletion options and subscription conditions. Look for research on the exact device and feature, ideally tested against an accepted reference method in people and settings relevant to you. Finally, let symptoms outrank the app. Chest pain, trouble breathing, fainting, sudden confusion or other signs of a medical emergency need prompt medical attention regardless of a high score. Persistent changes or concerns about GLP-1 side effects belong with a licensed clinician. Do not change medication, diet, supplements, exercise or blood-pressure care because of a readiness score alone.