Measurement of Physical Fitness and 24/7 Physical Activity, Standing, Sedentary Behavior, and Time in Bed in Working-Age Finns: Study Protocol for FINFIT 2021

Abstract

Background: Population studies gathering measured data on fitness and physical behavior, covering physical activity, standing, sedentary behavior, and time in bed, are scarce. This article describes the protocol of the FINFIT 2021 study that measures fitness and physical behavior in a population-based sample of adults and analyzes their associations and dose–response relationships with several health indicators. Methods: The study comprises a stratified random sample of 20–69-year-old men and women (n = 16,500) from seven city-centered regions in Finland. Physical behavior is measured 24/7 by tri-axial accelerometry and analyzed with validated MAD-APE algorithms. Health and fitness examinations include fasting blood samples, measurements of blood pressure, anthropometry, and health-related fitness. Domains of health, functioning, well-being, and socio-demographics are assessed by a questionnaire. The data are being collected between September 2021 and February 2022. Discussion: The study provides population data on physical fitness and physical behavior 24/7. Physical behavior patterns by intensity and duration on an hour-by-hour basis will be provided. In the future, the baseline data will be assessed against prospective register-based data on incident diseases, healthcare utilization, sickness absence, premature retirement, and death. A similar study will be conducted every fourth year with a new random population sample.

Measurement of Sedentary Behavior—The Outcomes of the Angle for Posture Estimation (APE) Method

“…This study is based on a subsample of the population-based FINFIT 2017 and 2021 studies [25,26]. These are cross-sectional population studies based on a stratified random sample of 20-69-year-old Finnish men and women from seven city-centered regions.…”

“…At the health examination of the study, participants' height and weight were measured, and they performed a 6 min walk test (6MWT) [25,26]. In short, the participants were asked to walk back and forth along a 15 m walking track as fast as possible for six minutes.…”

Reliability and Validity of Self-Reported Questionnaires Assessing Physical Activity and Sedentary Behavior in Finland

“…For the assessment of time in bed, the accelerometer was moved from the belt to an adjustable wristband and attached to the non-dominant wrist on the knuckles’ side. The accelerometer collected and stored the raw triaxial data in actual g-units in a ±16 G range at a 100 Hz sampling rate [ 29 ]. During waking hours, the mean amplitude deviation (MAD) was calculated based on the resultant acceleration signal in six-second epochs [ 30 ].…”

“…The determination of the body posture was based on the angle for posture estimation (APE) method, where the incident accelerometer orientation was assessed in relation to the reference gravity vector [ 15 ]. The posture was classified as standing if the APE was less than 11.6°, sitting if the APE was between 11.6° and 30.0°, reclining if the APE was between 30.0° and 73.0°, and lying otherwise [ 29 ].…”

What Can One Minute of the Day Tell about Physical Activity?

“…This study is based on a subsample of the population-based FinFit2017 and FinFit2021 studies [20,21]. The FinFit2017 and FinFit2021 are cross-sectional population studies based on a stratified random sample of 20-69-year-old Finnish men and women from seven city-centered regions.…”