Leveraging Walking Performance to Understand Work Fatigue Among Young Adults: Mixed-Methods Study

Background: Work fatigue negatively impacts personal health in the long term. Prior research has indicated the possibility of leveraging both walking parameters and perceptual measures to assess a person's fatigue status. However, an effective and ubiquitous approach to assessing work fatigue in young adults remains unexplored. Objective: The goals of this paper were to (1) explore how walking rhythms and multiple streams of data, including reaction time, self-reports, and an activity diary, reflect work-induced fatigue in the lab setting; (2) identify the relationship between objective performance and subjective perception in indicating fatigue status and fatigability; and (3) propose a mobile-based assessment for work-induced fatigue that uses multiple measurements. Methods: We conducted a 2-day in-lab study to measure participants' fatigue status using multiple measurements, including the stair climb test (SCT), the 6-minute walk test (6MWT), and the reaction time test. Both the SCT and the 6MWT were conducted at different points in time and under 2 conditions (measurement time, including prior to and after work, and pace, including normal and fast). Participants reported their fatigue perception through questionnaires completed before conducting walking tests and in an activity diary recorded over a week. Walking performance data were collected by a smartphone with a built-in 3-axis accelerometer. To examine the effect of fatigability on walking performance, we first clustered participants into 2 groups based on their reported mental fatigue level in the entry surveys and then compared their walking performance using a generalized linear model (GLM). The reaction time was examined using a 2-way repeated-measures GLM. We conducted semistructured interviews to understand participants' fatigue perception after each day's walking tests. Results: All participants (N=26; mean age 24.68 years) were divided into 2 groups-the fatigue-sensitive group (11/26, 42%) and the fatigue-nonsensitive group (15/26, 58%)-based on their mental subscores from 3 entry surveys: Fatigue Scale-14, Three-Dimensional Work Fatigue Inventory, and Fatigue Self-Assessment Scale (FSAS). The fatigue-sensitive group reported a significantly higher FSAS score in the before-work setting (t(50)=-3.361; P=.001). The fatigue-sensitive group covered fewer steps than the fatigue-nonsensitive group (beta(1)=-0.099; SE 0.019; t(1)=-5.323; P<.001) and had a higher step-to-step time variability in the 6MWT (beta(1)=9.61 x 10(-4); t(1)=2.329; P=.02). No strong correlation between subjective and objective measurements was observed in the study. Conclusions: Walking parameters, including step counts and step-to-step time variability, and some selected scales (eg, FSAS) were found to reflect participants'work-induced fatigue. Overall, our work suggests the opportunity of employing mobile-based walking measurements to indicate work fatigue among young adults.