Test-Retest Reliability of a Neuromuscular-Cognitive Assessment Battery, Without and With a Rucksack

Military personnel operate in chaotic and time-dependent environments; however, they are not assessed for readiness or return to duty under those constraints. Physical performance declines when integrated with cognitive challenges. Assessing this integrated performance (i.e., neuromuscular-cognitive) is vital to understanding how an individual may respond to uncertainty. Therefore, the purpose of this study was to determine the test-retest reliability of 3 neuromuscular-cognitive assessments, both with and without a rucksack.

This study employed a test-retest reliability study design. Three neuromuscular-cognitive assessments were utilized: single leg memory hop (SLMH), run decide (RD), and reactive agility (RA). An inertial measurement unit (IMU) was strapped to their lower back during the assessments. The SLMH included hopping as quickly and as far as possible in response to a stimulus. Reaction time, hop distance, and postural stability (root mean squared from the IMU) were used for analysis. The RD involves running and cutting 45 degrees to the left or right in response to a stimulus. Total time and decision making time were used for analysis. RA requires the individual to rapidly identify and deactivate a specific sensor out of 4 sensors placed on each corner of a 4 × 4m box. Average reaction time and linear acceleration were used for analysis. The RD and RA were also completed with a 45-pound rucksack and counterbalanced between visits 1 and 2. To assess the reliability of the measures, a Bland-Altman analysis was used, in addition to corresponding 95% Limits of Agreement and Lin's Concordance Correlation Coeficients (CCC). The University of Kentucky Institutional Review Board approved this study.

The bias indicated that all variables except the SLMH distance and normalized RA ruck reaction time had good agreement between visit 1 and visit 2. Further, the CCC suggested agreement for all variables except the SLMH reaction time and postural stability.

Overall, there was good agreement between visits 1 and 2 on the neuromuscular-cognitive assessment test with and without a rucksack. However, some variables showed some variability, with conflicting bias and CCCs. This must be considered as clinicians integrate and interpret neuromuscular-cognitive assessment test results.