Exercise & Training

Investigating the comparability of wearable accelerometer methods in the association between physical activity and cardiovascular disease: a cohort study using UK Biobank.

TL;DR

The dose-response associations between MVPA and cardiovascular disease varied markedly across three accelerometer-derived MVPA metrics, suggesting that research using a single accelerometer metric may caution about the interpretation of the association.

Key Findings

The study included 90,237 cardiovascular disease-free participants at baseline, with 1,298 incident strokes and 2,031 myocardial infarctions observed during follow-up.

  • Participants were drawn from the UK Biobank accelerometer sub-cohort recruited between 2013 and 2015 in the UK.
  • Outcomes were followed up until December 2022.
  • All participants were free of cardiovascular disease at baseline.

For stroke, a linear decrease in hazard ratio was observed with the machine-learning metric, but not with LFENMO and activity counts metrics.

  • Three accelerometer-generated MVPA metrics were compared: Low-pass Filtered Euclidean Norm Minus One (LFENMO), machine-learning, and activity counts.
  • Cox regression and restricted cubic splines were used to estimate dose-response associations for each metric.
  • LFENMO and activity counts did not show the same linear pattern for stroke as machine-learning did.

For myocardial infarction, machine-learning and LFENMO showed a curvilinear decrease in hazard ratios, whereas activity counts showed a linear decrease.

  • The shape of the dose-response curve for myocardial infarction differed depending on which accelerometer processing method was used.
  • Machine-learning and LFENMO produced curvilinear associations, suggesting diminishing returns or a threshold effect at higher MVPA levels.
  • Activity counts yielded a linear association for myocardial infarction, indicating a constant rate of risk reduction across the MVPA range.

The dose-response associations between MVPA and cardiovascular disease varied markedly across the three accelerometer-derived MVPA metrics.

  • The three metrics produced different shapes of association curves for both stroke and myocardial infarction outcomes.
  • The selection of accelerometer processing method influenced whether the observed association appeared linear or curvilinear.
  • This variation occurred despite all three metrics purporting to measure the same construct (MVPA) from the same underlying accelerometer data.

The study used restricted cubic splines within Cox regression models to characterize the shape of dose-response relationships for each metric.

  • Restricted cubic splines allow flexible, non-linear modeling of dose-response associations.
  • Cox proportional hazards regression was used to estimate hazard ratios across the range of MVPA exposure.
  • This analytical approach was applied consistently across all three MVPA metrics to enable direct comparison of association shapes.

What This Means

This research examined whether the way physical activity is measured by wrist-worn devices (accelerometers) affects what we conclude about the relationship between exercise and heart disease risk. Using data from over 90,000 UK Biobank participants, the researchers compared three different mathematical methods for converting raw accelerometer movement data into estimates of moderate-to-vigorous physical activity (MVPA): a signal-filtering approach (LFENMO), a machine-learning algorithm, and a traditional activity counts method. They then tracked who developed strokes or heart attacks over roughly a decade. The study found that the three methods told noticeably different stories. For stroke, only the machine-learning method showed a straightforward linear reduction in risk as physical activity increased, while the other two methods showed different patterns. For heart attacks, the machine-learning and signal-filtering methods suggested the protective benefits of activity level off at higher amounts (a curved relationship), while the activity counts method suggested risk keeps dropping steadily with more activity. These differences in curve shape were meaningful and not trivial. This research suggests that conclusions drawn from studies on physical activity and heart disease may depend heavily on which technical method researchers choose to process accelerometer data, even when the underlying device data are identical. This has important implications for how public health guidelines are developed and how individual studies should be interpreted, since a finding from one study using one processing method may not be directly comparable to findings from another study using a different method.

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Citation

Lapointe Y, Kapur A, Sharma A, Panter J, Fuller D, Mamiya H. (2026). Investigating the comparability of wearable accelerometer methods in the association between physical activity and cardiovascular disease: a cohort study using UK Biobank.. Preventive medicine. https://doi.org/10.1016/j.ypmed.2026.108603