Do wearable fitness devices correlate with performance-based tests of work-related functional capacity?

Background: The use of wearable accelerometers in conjunction with Functional Capacity Evaluation (FCE) may provide additional useful information about maximum performance in workers and enhance the validity of functional testing. However, little research has been conducted to compare accelerometer output with performance during FCE.

Objective: The objectives of this study were to: (1) Determine the magnitude and direction of correlation between participant performance on five FCE tasks and scores from Actigraph activity monitors; and (2) Compare the results of two different placements of Actigraph devices.

Method: We used a cross-sectional design and convenience sampling to collect data from 46 healthy participants. Each participant completed 5 functional tasks selected from the WorkWell FCE protocol while wearing 2 Actigraph devices, 1 on the dominant side waist and 1 on the non-dominant wrist. The FCE tasks included 5-repetition maximum lifting (floor-to-waist, waist to crown and front carry), a sustained overhead work endurance task, and the 6-minute walk test. Analysis included calculating Pearson regression coefficients between maximum FCE item performance and Actigraph vector magnitudes (VM) along with Intraclass Correlation Coefficients (ICC) to compare VM activity counts derived from the Actigraphs on the waist and wrist.

Results: Thirty-Nine (84.8%) participants had complete data and were included in analysis. Findings indicate Actigraph VM data from the device worn on the waist correlated positively with maximum lift performance (r = 0.39-0.64, p < 0.001 to 0.08) and 6-minute walk distance (r = 0.66, p < 0.001). Actigraph data from wrist placement were not significantly correlated with FCE performance on any of the functional tasks, except when comparing average VM data and waist to crown lift (r = 0.44, p < 0.001). There was no significant correlation in either Actigraph placement for VM and overhead work time. ICCs between the two Actigraph placements ranged from poor to acceptable agreement (ICC = 0.24-0.70, p < 0.001 to 0.19).

Conclusions: Actigraph device output correlated moderately with maximum performance on FCE lift and ambulation tests. Waist placement appears more suitable than wrist during performance-based tests.