A landmark study drawing on nearly 2,000 surgical patients from the NIH’s All of Us Research Programme has quantified what clinicians have long suspected: postoperative step count, measured by a consumer wearable, is a robust, independent predictor of hospital length of stay, complications, and readmission. Published in the Journal of the American College of Surgeons on 6 May 2026, the findings challenge the clinical value of heart rate variability monitoring and patient self-reported wellness scores as postoperative recovery tools.
Walk enough steps after your operation and, according to a compelling new study, you are measurably less likely to suffer a complication, be readmitted to hospital, or spend longer than necessary in a hospital bed. The research, led by investigators at The Ohio State University Wexner Medical Center, puts precise numbers on the benefits of postoperative mobility for the first time – and the signal is striking. Each additional 1,000 steps per day taken in the postoperative period was independently associated with an 18% reduction in the odds of complications, a 16% reduction in readmission risk, and a 6% shortening of hospital stay.
The investigators used data from the NIH’s All of Us Research Programme – a large, richly characterised cohort that links electronic health records (EHRs) with voluntary Fitbit wearable data – to identify 1,965 adult patients who underwent inpatient surgery and had at least 30 days of preoperative and postoperative wearable coverage. That stringent inclusion criterion, applied from an initial pool of 66,345 surgical patients, produced a cohort with sufficient data to examine not only postoperative step counts but also changes in heart rate variability (HRV) and self-reported wellness, measured using the validated SPADE composite score (which captures fatigue, pain, anxiety, depression, and sleep disruption).
Step counts outperform every other metric tested
The headline finding is unambiguous. On multivariable analysis – adjusted for age, sex, surgical risk category, BMI, Charlson Comorbidity Index, and neighbourhood deprivation index – postoperative change in daily steps was the only wearable-derived metric consistently associated with every primary outcome. Specifically, each incremental 1,000-step increase per day relative to preoperative baseline was associated with a reduced length of stay (incidence rate ratio 0.94, 95% CI 0.90–0.99) and lower odds of both 30-day (adjusted OR 0.83, 95% CI 0.69–1.00) and 90-day (adjusted OR 0.82, 95% CI 0.70–0.96) complications. The same pattern held for readmission: 30-day readmission odds fell by 15% (aOR 0.85, 95% CI 0.76–0.96) and 90-day readmission odds by 16% (aOR 0.84, 95% CI 0.75–0.94) per additional 1,000 postoperative steps per day.
The clinical magnitude of those effects becomes clearer in the scenario analyses. A swing from –1,000 to +1,000 steps per day relative to preoperative baseline trans-lated to a reduction in mean length of stay from 2.60 days to 1.92 days – a difference of roughly 0.68 days, or 35.5%. The effect was most pronounced in high-risk surgical procedures (23.5% reduction) and was meaningful even in low-risk cases (17.5% reduction).
Senior author Timothy M. Pawlik, professor and chair of surgery at Ohio State, framed the finding in practical terms. “We tell patients that they need to get up and walk after an operation, but we don’t have a good sense of how much they’re actually moving,” he said. “Wearables give us an objective, continuous readout. Instead of asking how you feel, we can see that you’re up and moving, which is a very actionable signal of how your recovery is progressing.”
Heart rate variability and wellness scores fall short
By contrast, neither postoperative changes in HRV nor the SPADE self-reported wellness composite reached statistical significance for any of the primary outcomes. Changes in HRV – operationalised from wrist photoplethysmography-derived SDANN values – showed no association with length of stay (IRR 1.55, 95% CI 0.93–2.61, p = 0.275), 30-day complications (p = 0.61), or 90-day readmission (p = 0.75). SPADE scores likewise failed to independently predict any postoperative outcome in fully adjusted models.
The authors are careful to contextualise the HRV null result. “HRV demonstrates a modest association with complications and readmissions, consistent with the concept that preserved parasympathetic (vagal) tone confers resilience to surgical stress,” they write in the paper’s Discussion section. The lack of statistical significance may partly reflect methodological limitations inherent to consumer-grade wrist photoplethysmography, which is noisier and less accurate than electrocardiography-derived RR-interval measurements, particularly in free-living postoperative settings where motion artefact, opioid use, neuraxial anaesthesia, and atrial fibrillation can all distort the signal.
The authors’ view is that HRV retains clinical relevance – but at a different point in the surgical pathway. “HRV appears most useful as a preoperative triage tool to identify patients who might benefit from prehabilitation (e.g., HRV-biofeedback or breathing interventions) rather than as a standalone postoperative monitoring target,” they note.
The failure of SPADE to predict outcomes is arguably the more provocative finding for those invested in patient-reported outcome measures. Self-reported wellness, the authors suggest, may be systematically confounded by pain, medication effects, environmental stressors, and social-desirability bias in ways that decouple subjective experience from objective physiological recovery. That does not render PROMs useless – “in a multimodal framework, PROMs may still add context, such as capturing pain interference, sleep quality, or mood, that can guide targeted symptom relief,” the authors acknowledge – but it does argue against relying on them as a primary signal for discharge decision-making.
From wrist to ward: what this means for clinical practice
Pawlik acknowledges the chicken-and-egg complexity of the relationship between mobility and recovery. “People who feel better are naturally more likely to be up and around,” he said. “However, the signal is so strong that it suggests step count is not just a marker of wellness, but a key component of it. Seeing a patient’s step count drop can be an early indicator to intervene, perhaps by involving physical therapy or checking in more frequently.”
That interpretive nuance matters. The study’s observational design cannot establish causation, and the authors are candid about the risk of confounding by indication: sicker patients may simply walk less, and some procedures mandated reduced early mobility. Rehabilitation status was unavailable in the All of Us dataset, meaning patients enrolled in formal postoperative physiotherapy programmes could not be distinguished from those without structured support.
Despite those caveats, the practical implications are considerable. The findings align with, and extend, a prior All of Us analysis in which preoperative step counts above 7,500 per day were associated with a 51% reduction in postoperative complication risk. The current study adds postoperative data and specifies which complications were most sensitive to activity level – respiratory events and venous thromboembolic complications showed the strongest associations, reinforcing well-established mechanistic links between immobility, pulmonary stasis, and thrombogenesis.
We tell patients that they need to get up and walk after an operation, but we don’t have a good sense of how much they’re actually moving.
The authors argue that these findings support integrating wearable step-count data into Enhanced Recovery After Surgery (ERAS) pathways as dynamic, patient-specific targets rather than generic milestones. “If a patient’s goal is 8,000 steps before surgery and 6,000 on postoperative day three, they can see if they’re hitting those targets,” Pawlik said. “It gives them a concrete goal and gives us objective data to help decide if they’re ready for discharge or if they need more support at home.”
The authors envision a two-phase wearable integration strategy: preoperative HRV-informed risk stratification to identify patients who might benefit from prehabilitation, followed by postoperative step-guided recovery management with trend-based alerts to trigger earlier clinical review when activity falters. “Future trials should test whether step-target interventions and HRV-based prehabilitation improve outcomes across surgical risk strata,” they conclude.
For a healthcare system still grappling with avoidable readmissions and prolonged hospital stays, the message is simple: the number of steps your patient takes after surgery may tell you more about their recovery than anything they – or their autonomic nervous system – are able to report.
Reference:
Elemosho, A., Chatzipanagiotou, O. P., Angez, M., et al. (2026). Association of perioperative steps and heart rate variability from wearable devices with surgical outcomes. Journal of the American College of Surgeons. https://doi.org/10.1097/XCS.0000000000001857
