The conundrum faced by clinicians in prescribing physical activity, as mentioned in the article, is the difference between the information provided by self-reported questionnaires and the data from fitness trackers. Questionnaires rely on patients' self-reports about their behavior (like specific activities they do), while fitness trackers measure actual movements or accelerations of the body in real time. This difference creates a challenge for clinicians: should they base their exercise prescriptions on the behavior-based information from questionnaires or the more detailed movement data from fitness trackers? This dilemma arises because both methods offer valuable but different types of information about physical activity.
Yes, the authors of the article did suggest a solution to this conundrum. They recommend that clinicians should first encourage any amount and intensity of physical activity for patients just starting out, particularly because even small amounts of physical activity are beneficial. For those who are already active and aiming for a specific target, the recommendation is to follow the guideline of 150 minutes a week of moderate to vigorous physical activity. Additionally, for those who prefer tracking steps, setting a goal of about 7000 steps per day for older individuals and about 9000 steps per day for younger ones is reasonable. This approach combines the insights from both questionnaires and fitness tracker data, allowing for more personalized and effective physical activity prescriptions.
==When faced with a discrepancy between digital signals and a patient's subjective feedback, clinicians should not solely rely on either but rather consider both sources of information. Digital tools provide objective data, which is valuable, but they may not capture the full spectrum of a patient's experience, especially subjective aspects like sleep quality or psychological factors. On the other hand, subjective feedback can be influenced by individual perceptions or other factors unrelated to actual sleep patterns. The best approach is a balanced one, taking into account both the objective data from digital tools and the subjective experiences reported by the patient. This comprehensive view allows for a more accurate assessment and appropriate intervention.==
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# Fitness Trackers to Guide Advice on Activity Prescription
[I-Min Lee, MBBS, ScD1,2](https://jamanetwork.com/searchresults?author=I-Min+Lee&q=I-Min+Lee); [Sarah K. Keadle, PhD3](https://jamanetwork.com/searchresults?author=Sarah+K.+Keadle&q=Sarah+K.+Keadle); [Charles E. Matthews, PhD4](https://jamanetwork.com/searchresults?author=Charles+E.+Matthews&q=Charles+E.+Matthews)
Author Affiliations [Article Information](https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#249338277)
JAMA. 2023;330(18):1733-1734. doi:10.1001/jama.2023.19332
“Everything that worsens with age gets better with exercise,” Professor Ralph Paffenbarger, a pioneer in the field of physical activity epidemiology, used to remark to his students. There are now 7 decades of data showing physical activity to be crucial for health and well-being,<sup><a href="https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#jvp230130r1" data-tab-toggle=".tab-nav-references">1</a></sup> buttressing Paffenbarger’s at-first-blush hyperbolic statement. These findings, primarily from studies using self-reported physical activity, underpin guidelines calling for 150 to 300 minutes a week of moderate-intensity physical activity (eg, brisk walking), 75 to 150 minutes a week of vigorous-intensity physical activity (eg, jogging), or equivalent combination of the 2, for substantial health benefits, as well as muscle-strengthening exercises 2 days a week.<sup><a href="https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#jvp230130r2" data-tab-toggle=".tab-nav-references">2</a></sup><sup>,<a href="https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#jvp230130r3" data-tab-toggle=".tab-nav-references">3</a></sup>
In the past decade, the proliferation of wearable devices used in large studies and fitness trackers sold on consumer markets has fundamentally changed the field by making available far more detailed and precise data. Consumer wearable devices display many health metrics,<sup><a href="https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#jvp230130r4" data-tab-toggle=".tab-nav-references">4</a></sup> including physical activity metrics that are (eg, minutes in physical activity) or are not (eg, daily steps taken) reflected in current recommendations. They also record novel metrics that cannot be assessed or are not well assessed by self-report, and thus are not part of current physical activity guidelines, such as limiting sedentary time, increasing time in light-intensity physical activity (eg, light household chores), engaging in 1- to 2-minute “bursts” of vigorous activity in daily life (eg, climbing stairs, speeding up to catch a bus), or tracking a daily step goal. These new data present many exciting opportunities to fill knowledge gaps that can inform future guidelines. However, clinicians may view the onslaught of new information from wearables less enthusiastically, as it can be confusing, complicating the already challenging task of effectively prescribing physical activity to patients.
This Viewpoint seeks to clarify the state of current knowledge by discussing whether older self-report questionnaire studies and newer device studies reach different conclusions about the dose of physical activity needed for health. Based on the most up-to-date evidence, how much or how little physical activity should physicians recommend their patients?
It is important to understand that questionnaires and devices measure related—but not identical—physical activity constructs. Questionnaires typically ask about activities in which a participant engages; that is, they ask about _behavior_. Devices, in contrast, simply measure _movements_, or more accurately, accelerations, of the body rather than specific behaviors; they agnostically record participant accelerations in real time ([Figure](https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#jvp230130f1)). These signals are then translated by algorithms into understandable behavior-oriented metrics, such as time spent in physical activity of different intensities, steps taken, or activity types (eg, sitting, standing, walking, running, cycling). Adding to the confusion, there presently are no standard algorithms for translation, although research is ongoing. An illustration of the related but nonidentical constructs is to consider someone who reports playing pickleball (a racket sport) for 2 hours (a specific behavior): their device will not show 7200 seconds (2 hours × 60 minutes × 60 seconds) of uniform, continuous moderate to vigorous exercise, but “bursts” of acceleration depending on the pace of the game ([Figure](https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#jvp230130f1)).
Figure. Sample Tracings From Wrist-Worn, 3-Axis Accelerometers Sampling at 80 Hz
[](https://cdn.jamanetwork.com/ama/content_public/journal/jama/939261/jvp230130f1_1698955726.04441.png?Expires=1703318149&Signature=Vefob9en~Zsum-SVD1NNY85uSBGxYMe~6deUVssKJOgEUWTAZEezYezWGPhn6nqxDeibPiIlnfS3v140PVZqu8uN6GwOn7r33-Z1GdGCJ06Mv4EqxqMbAnTBefrwemR8sGNBmU-h6OIYXULve1PDvQfnZoqfITvhMGOcrcJecKTqI~UT9Sjq8CgdU59in5BpIcY1ZF5s0QFq6-ai1-zR1IPduP3oiUKD7IzEdSARLSR3xd4zT61WYB5bNurxiC57K3nTiwHV1m2QhGXWdDE4KxznYNhy8l~N5lZ-~DEr~J3bQya~n05dp076qMD2dLKb7pSjr3XZYiczMvh2cE0Y6g__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
The 3 colors represent data collected by accelerometers on 3 orthogonal axes of movement (blue, x; red, y; black, z); the larger the amplitude, the more vigorous the activity. Statistical algorithms are applied to the device signals to estimate physical activity metrics such as time spent in different activity types or intensities and step counts. A, Tracings from 2 hours of pickleball (a racket sport resembling tennis or table tennis); B, tracings from 30 minutes of dog walking. Tracings were obtained from participants who wore a device and reported their behaviors as 2 continuous hours of pickleball and 30 continuous minutes of dog walking, respectively. Both activities are conventionally classified as moderate to vigorous intensity, but as the tracings indicate, the device signals clearly show variation within and between behaviors. In pickleball, the tracing shows several “bursts” of larger amplitude, as well as periods of very little signal (possibly for water breaks). In contrast, the dog walking signals are more uniform and continuous, with only a small number of brief pauses with small amplitude (possibly, to cross a street or wait for the dog to catch up).
This raises a conundrum: a clinician gives advice on healthy behavior, information for which is obtained from questionnaires, albeit imprecisely, yet devices measure movements in greater detail and more precisely. Thus, given the current knowledge base, should clinicians provide exercise prescriptions based on behavior or device data?
When comparing findings from questionnaire and device studies, intriguingly, the dose-response curve describing the relationship between physical activity and health outcomes is remarkably similar between studies<sup><a href="https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#jvp230130r5" data-tab-toggle=".tab-nav-references">5</a></sup>—a curvilinear relationship that can be succinctly summarized as showing “some is good; more is better” up to a point beyond which the curve plateaus. A major difference, however, is the magnitude of risk reduction. With device studies, the magnitude of risk reduction is far larger: for example, at the guideline dose of physical activity, device studies report about 50% to 60% lower risk for all-cause mortality and questionnaire-based studies about 20% to 30% lower risk.<sup><a href="https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#jvp230130r5" data-tab-toggle=".tab-nav-references">5</a></sup>
One possible metric bridging the gap between the constructs of “behavior” and “movement” is step counts. A step is a step, rendering moot the lack of congruence between constructs. Furthermore, steps are easily understood and intuitive. Current guidelines do not stipulate a step goal because few data were available at the time of the 2018 US guidelines.<sup><a href="https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#jvp230130r1" data-tab-toggle=".tab-nav-references">1</a></sup> Recently, there has been much enthusiasm investigating steps for health—eg, asking if people really need 10 000 steps a day (the short answer is no). Research on steps yields similar findings to time spent in moderate to vigorous physical activity: there is a dose-response curve showing that “some is good; more is better” up to a point beyond which the curve plateaus.<sup><a href="https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#jvp230130r6" data-tab-toggle=".tab-nav-references">6</a></sup> For those aged 60 years or older, the plateau for all-cause mortality occurs at 6000 to 8000 steps a day; for those younger, 8000 to 10 000 steps a day. It is currently unclear whether faster steps yield additional benefits after accounting for step counts.
Additional considerations, noted above, are that devices can assess light-intensity physical activity far better than self-reports and can record sporadic, short bursts of vigorous physical activity; results from ongoing and future studies will help inform future recommendations, potentially including these new intervention opportunities. For those unable or unwilling to engage in the sustained moderate to vigorous physical activity currently recommended, it is encouraging that accumulating data show that these “easier” kinds of physical activity, which are part of daily living, also are associated with health benefits.<sup><a href="https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#jvp230130r7" data-tab-toggle=".tab-nav-references">7</a></sup><sup>,<a href="https://jamanetwork.com/journals/jama/fullarticle/2810684?guestAccessKey=f4006ad0-d28e-43fe-bc80-9ae5aacee3f4&utm_source=fbpage&utm_medium=social_jama&utm_term=11815043581&utm_campaign=article_alert&linkId=248257483&fbclid=IwAR1WIyz79VRDaEQfH4CRNGDzIZzZpXLA0II1BOx3NV8KE24QoHkFaRytBXg_aem_Af9CSINumiK5aK3rioZ_A5HkoJPiBm2Tg-nGfR4EeDl3_OapDn43_vYQ276kzaxnIgM#jvp230130r8" data-tab-toggle=".tab-nav-references">8</a></sup> Finally, the optimal amount of physical activity likely varies depending on the clinical outcome; as research using devices accrues, it will become increasingly feasible for clinicians to offer personalized prescriptions addressing individual patient needs and goals.
In conclusion, the new data from device studies strongly buttress older data from questionnaire studies that underpin current physical activity guidelines. To keep up with technology, future guidelines should incorporate device-measured physical activity metrics, including step counts, as evidence accumulates. Encouragingly, current device studies support that no physical activity is too little to be healthful. Based on the totality of evidence, clinicians should first encourage _any_ amount and intensity of physical activity for a patient just starting. Next, for those who already do some physical activity and want to reach a target dose, 150 minutes a week of moderate to vigorous physical activity should be recommended. For those preferring to monitor steps, a goal of about 7000 steps a day is reasonable for those aged 60 years or older, and about 9000 steps a day if younger. Critically, clinicians themselves should hew to this same advice not only to set an example but also to personally experience and understand potential barriers that can exist.
Everyone ages, but with any dose of physical activity, we can mitigate declines in health and function with passing years.
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Article Information
**Corresponding Author:** I-Min Lee, MBBS, ScD, Brigham and Women’s Hospital, Harvard Medical School, 900 Commonwealth Ave E, Boston, MA 02215 ([
[email protected]](mailto:
[email protected])).
**Published Online:** October 9, 2023. doi:10.1001/jama.2023.19332
**Correction:** This article was corrected on October 30, 2023, to fix a typo in the Figure.
**Conflict of Interest Disclosures:** None reported.
**Disclaimer:** The opinions expressed by the authors are their own, and this material should not be interpreted as representing the official viewpoint of the US Department of Health and Human Services, the National Institutes of Health, or the National Cancer Institute.
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