Twenty-one trials of activity trackers found no blood pressure benefit

The premise of a fitness tracker as a health device is a chain of assumptions: the device measures activity, measurement prompts more activity, more activity lowers blood pressure. Each link is plausible. A systematic review published this month tested whether the chain holds end to end in randomised trials, and found that it does not — at least not measurably [s1].

What was pooled

The authors followed PRISMA 2020, registered the protocol on PROSPERO as CRD42023442506, and searched PubMed, MEDLINE, the Cochrane Library and IchuShi-Web, the Japanese medical literature database [s1].

They identified 21 randomised controlled trials of interventions using wearable devices to promote physical activity, in participants with hypertension, type 2 diabetes, or overweight or obesity [s1]. Interventions ran from 12 to 48 weeks and used pedometers, activity trackers and smartwatches [s1].

The result

A random-effects meta-analysis found no statistically significant improvement in systolic or diastolic blood pressure at any intervention duration — not at 12 weeks, not at 24, not at 48 [s1].

The secondary outcomes went the same way. No statistically significant improvements were found in body weight, fasting blood glucose or HbA1c [s1]. Heterogeneity varied from low to high depending on the outcome and the intervention period [s1].

The authors' conclusion is that current evidence for direct intervention using wearable devices to promote physical activity is insufficient to establish clinically meaningful improvements in blood pressure and related metabolic parameters [s1].

Reading a null result properly

Three things are worth separating here, because a null meta-analysis is easy to over-read in either direction.

First, this is a test of a specific intervention design: giving someone a device to promote activity, as the intervention. It is not a test of whether physical activity lowers blood pressure — the authors take that as established, describing improved physical activity as an effective way to manage hypertension [s1]. The failure being reported is in the delivery mechanism, not the underlying physiology.

Second, "no statistically significant improvement" across 21 trials with heterogeneity ranging up to high is a weaker statement than "these devices do not work." Twenty-one trials is a modest evidence base for a question with this much variation in device type, population, duration and behavioural support, and pooling across pedometers and smartwatches assumes those interventions are comparable in a way they may not be.

Third, the populations were clinical — people with hypertension, type 2 diabetes, or overweight or obesity [s1] — not the general consumer buying a smartwatch. That makes the trials more relevant to whether a health system should hand out devices than to whether an individual's purchase is worthwhile, and the two questions have different answers about what else is bundled with the device.

The authors themselves point in that direction. Their suggestion is that future research may need to integrate wearable technology into comprehensive care models combining targeted feedback, education and behavioural support, rather than relying on monitoring alone [s1]. The plausible reading of the null result is that the device is a data-collection tool, and data collection is not an intervention.

A number in the abstract that does not hold

The paper opens by stating that hypertension affects more than 4 billion people worldwide [s1]. That figure does not match the standard global estimate and should not be repeated.

The reference source for global hypertension prevalence is the NCD Risk Factor Collaboration's pooled analysis of 1,201 population-representative studies covering 104 million participants, which estimated that among people aged 30 to 79 the number with hypertension doubled between 1990 and 2019 — from 331 million women and 317 million men to 626 million women and 652 million men [s2]. That is roughly 1.28 billion adults in that age band, against a stable global age-standardised prevalence [s2].

The error does not affect the meta-analysis, which is about trial outcomes rather than prevalence. It is worth flagging because introductory figures get quoted onward more readily than results do.

What the same body of evidence says about the problem

The NCD-RisC analysis is also the better guide to why blood pressure interventions matter. In 2019, 59% of women and 49% of men with hypertension reported a previous diagnosis, 47% of women and 38% of men were being treated, and control rates among people with hypertension were 23% for women and 18% for men [s2].

The gap there is mostly diagnosis and treatment, not activity promotion. That framing puts the wearable result in proportion: the intervention that failed to move blood pressure in these trials was never the one carrying most of the population-level burden.

What to watch

Whether trials that bundle wearables with structured coaching, clinician feedback or medication management show the effect that devices alone did not — which is the design the authors of this review recommend testing [s1].

This article is informational and does not constitute medical advice.

Sources

• [s1] Effects of physical activity-promoting wearable devices on blood pressure in adults: a systematic review and meta-analysis — Hypertension Research, published online 29 July 2025. https://doi.org/10.1038/s41440-025-02260-6
• [s2] Worldwide trends in hypertension prevalence and progress in treatment and control from 1990 to 2019 — The Lancet, 2021. https://doi.org/10.1016/S0140-6736(21)01330-1