Impact of Sedentary Behavior & Physical Activity on Mortality

Background and Purpose

Sedentary behavior and physical activity are related but distinct aspects of daily movement. People can spend many hours sitting while also meeting exercise guidelines, and the amount and pattern of movement may have different associations with mortality. Research using accelerometers and other devices has advanced the measurement of these behaviors and their relationship with mortality. The opportunity for new work lies in a question and analysis that add to this existing evidence.

Recent studies have examined total sedentary time, activity intensity, daily steps, movement patterns, and their joint associations with mortality. A recent preprint developed models using wearable-derived step count and walking cadence to predict five-year mortality in UK Biobank and validated them in U.S. National Health and Nutrition Examination Survey (NHANES) data. It illustrates the growing use of large linked datasets and objective measures. Proposals should explain how their work would extend, test, or differ from relevant studies rather than reproduce an established association.

This request welcomes two possible approaches: evaluating whether sedentary and activity measures improve the prediction of mortality, or examining what can credibly be inferred about their effects on mortality. Researchers may propose one approach or a well-justified combination. These approaches answer different questions and should not be treated as interchangeable. A predictive association alone does not establish that changing a behavior will change mortality.

The study should use a sufficiently large dataset with objective measures of movement and linked mortality outcomes. Potential sources include UK Biobank, All of Us, or other datasets that meet these requirements. Self-reported sitting or exercise alone should not serve as the primary exposure measure. The research need not demonstrate that sedentary behavior has risen over time or estimate its contribution to historical mortality improvement.

The results should help actuaries understand the relevance and limits of the evidence on mortality risk. This RFP does not require insured experience data, a separate insured-population model, or a recommended change to an actuarial mortality assumption.

Research Objective

The objective is to produce a credible, clearly differentiated analysis of objectively measured sedentary behavior and physical activity in relation to mortality. Researchers should identify a specific unanswered question, choose methods suited to that question, and show what is learned by considering sedentary behavior alongside physical activity and other relevant risk factors. The central outcome is all-cause mortality. Cause-specific mortality may be included where follow-up and event counts support reliable analysis.

Proposals should address the following components.

Research Question and Contribution

State the principal research question and whether the study is designed primarily for mortality prediction, causal interpretation, or a justified combination. Explain why the question matters and what the proposed analysis can establish.
Identify the relevant published and emerging work, including studies based on large device-measured cohorts. Explain the specific new contribution, such as the added value of sedentary time or its pattern beyond activity measures, a credible joint analysis, stronger validation, or a better-defined causal question.

Movement Measures and Data

Define objective measures of sedentary behavior and physical activity. Depending on the question and data, measures may include total sedentary time, duration of uninterrupted periods, breaks in sedentary time, steps, cadence, movement intensity, or other device-derived measures. State which are primary and why.
Explain device placement, wear time, data processing, and whether the selected measure identifies posture or instead uses low movement as a proxy for sitting. Address the distinction between waking sedentary time, sleep, device nonwear, and light activity.
Describe the dataset, population, years of collection, current or anticipated access, mortality linkage, follow-up, number of deaths, and restrictions on use or publication. Justify sample and event counts for the proposed outcomes and subgroup analyses. UK Biobank and All of Us are examples, not required sources.

Mortality Analysis

Analyze all-cause mortality as the principal outcome. Consider cardiovascular or other cause-specific mortality only with a clear rationale and sufficient events; specify any implications of competing risks or cause-of-death classification.
Examine the relationship between sedentary and activity measures, including their joint distribution or interaction where useful. Clarify what can be learned from total activity or steps versus sedentary duration or pattern, and avoid interpreting a low-activity measure as a direct measure of sitting without validation.
Address age and sex, and other population differences where the data are credible. Present uncertainty and both the statistical and practical magnitude of findings. Avoid extensive subgroup analyses that exceed the available information.

Methods for the Chosen Research Approach

For a prediction study, compare prespecified baseline and expanded models; evaluate discrimination, calibration, and the incremental value of movement measures. Use internal validation and, where feasible, external validation. Identify the intended prediction horizon and account for differences between development and validation populations.
For a causal study, specify the proposed exposure contrast, comparison strategy, assumptions, and how the analysis will address confounding and reverse causation. Discuss physical activity, obesity, smoking, preexisting disease, disability or frailty, and socioeconomic factors as relevant. Use appropriate lags and sensitivity analyses, and limit causal claims to what the design supports.
For either approach, test sensitivity to plausible measurement and analytic choices. Explain whether results reflect mortality risk associated with current behavior, sustained exposure, or a modeled change in behavior; these interpretations should be kept distinct.

Interpretation and Limitations

Discuss how the findings could inform an actuary’s understanding of mortality risk, including what they do and do not imply for insured populations or assumption setting. This should be an interpretation of the research findings, not a separate actuarial modeling workstream.
Describe the effects of sample selection, measurement error, incomplete follow-up, data access, and differences between the study population and populations to which readers might apply the findings.

The Society of Actuaries Research Institute’s Mortality and Longevity Strategic Research Program Steering Committee encourages focused proposals that match the research question and analytic breadth to the quality and credibility of the available data. Preference will be given to work that adds a clear contribution to existing research and communicates its conclusions and limitations accessibly.

Proposal Requirements

Proposals should include the following information.

Resumes for all researchers, including graduate students expected to participate, with one lead researcher designated as the primary contact. The submitter must be authorized to speak for the research team and its firm or institution.
A concise statement of the question, intended contribution, study population, primary outcome, and chosen predictive or causal approach.
A targeted review of related work that identifies the gap this project would address. Proposers should explain how the work differs from existing large-cohort device studies and why the anticipated results would be useful to the SOA Research Institute’s audience.
A detailed description of the proposed data and methods, objective movement measures, comparison or baseline models, mortality follow-up, event counts, validation or identification strategy as applicable, uncertainty, and key sensitivity analyses.
A data-access and feasibility plan stating current permissions, any approvals or licensing needed, timing and costs, publication or sharing restrictions, and a contingency if a proposed source becomes unavailable.
Project risks and proposed responses, including limits imposed by sample selection, event counts, exposure measurement, confounding, or external validity.

Expected deliverables should include the following.

A written report presenting the question, prior evidence, data, methods, results, sensitivity analyses, conclusions, and limitations in language accessible to actuarial practitioners.
A one-page executive summary that can stand alone.
Exhibits that communicate the principal measures, mortality results, uncertainty, and any meaningful differences among populations or models.
Definitions, model specifications, and supporting code or documentation sufficient to understand and, where permissions allow, reproduce the analysis; any sharing restrictions should be explained.
A concise discussion of potential actuarial relevance and the limits of applying findings to insured populations; and possible presentations at continuing education sessions, either virtually or in person.

Cost estimates should include computing, data access or licensing, salaries, report preparation, and other material costs. Hourly rates should be accompanied by estimated hours. Any guaranteed total cost should be stated. Cost will be considered but will not necessarily be decisive. The SOA Research Institute generally does not fund academic institution overhead expenses.

As a guide to developing the budget, please review the Historical Project Cost Guide in the Appendix. Proposals should provide a schedule for data acquisition, interim review, draft deliverables, revision, and final delivery, and describe how the team will meet that schedule.

Other factors demonstrating the proposer’s ability to complete the research to a high standard should also be described. Proposals must be no more than five pages, excluding references and researcher biographies.

Selection Process

The Mortality and Longevity Strategic Research Program Steering Committee will appoint a Project Oversight Group to oversee the project. The Project Oversight Group is responsible for recommending a proposal for funding. Input from other knowledgeable individuals may also be sought. The recommendation is subject to approval by SOA Research Institute leadership. An SOA staff research actuary will provide staff support.

Questions

Questions regarding this request for proposals should be directed to research-ML@soa.org.

Submission of Proposal

Please email your proposal to research-ML@soa.org. Proposals must be received no later than January 11, 2027.

Conditions

The selection of a proposal is conditioned upon and is not final until a Letter of Agreement is executed by both the SOA Research Institute and the researcher.

The SOA Research Institute reserves the right not to award a contract for this research, including for a lack of acceptable proposals or insufficient funding, and may redirect the project as it deems advisable.

The SOA Research Institute plans to hold the copyright to the research and to publish the results with appropriate credit to the researchers. The Institute may seek public exposure for the research; researchers selected for the project agree to participate in reasonable promotional communications, which may include a webcast, presentation, or article.

Conflict of Interest

Proposers agree to disclose any material business, financial, and organizational interests or affiliations that are or may reasonably be construed as related to the interests, activities, or programs of the SOA Research Institute.

Appendix

Historical Project Cost Guide. These ranges reflect the 33rd to 66th percentiles of project costs in the supplied SOA RFP and are included here as provisional budget guidance.

All Contracted Projects

The 33rd to 66th percentile project cost range is $25,000 to $50,000.

Literature Reviews

The 33rd to 66th percentile project cost range is $15,000 to $20,000.

Surveys

The 33rd to 66th percentile project cost range is $28,000 to $55,000.