Impact Of Neurocognitive Loading On Lower Limb Coordination And Variability During A Single Leg Hop

PURPOSE: An increasing number of performance tests are incorporating cognitive tasks. There is little research on how these tasks affect lower limb joint coordination. This study aims to examine a neurocognitive load’s impact on hip and knee joint coordination in a hopping task. METHODS: Forty-nine athletes (29 DI, 20 recreational) performed 16 trials of a single leg cross over hop task in the presence (16 trials) or absence (16 trials) of a neurocognitive load. For the load conditions, subjects reacted to two lights in their peripheral vision, one illuminated green the other red, initiating the hop task in the green light’s direction. A 10-camera motion analysis system recorded the displacement of retroreflective markers placed over bony landmarks. The first hop of each trial was divided into 4 phases. Phase 1: initial toe off (TO) to maximum vertical displacement of the pelvic center of mass (mxPCoM), phase 2: mxPCoM to foot contact (FC), phase 3: FC to minimum vertical displacement of the pelvic center of mass (mnPCoM), and phase 4: mnPCoM to TO. For each phase the mean absolute relative phase (MARP) and deviation phase (DP) were derived and grouped according to athlete, extremity, and load condition. Differences in outcomes were tested using a linear mixed model with fixed effects for neurocognitive load and phase and a random intercept to account for correlation between trials from same subject. Contrasts comparing load vs no load within each phase were performed at an alpha level of significance of 0.05. RESULTS: Significant differences (p < 0.01) in the MARP and DP between the two load conditions were noted. The mean no load MARP (± 1 S.D.) for phases 1, 2, 3, and 4 were 96.3 (± 1.9), 40.0 (± 1.9), 55.1 (± 1.9), and 108.2 (± 1.9), respectively and for the load MARP they were 69.5 (±1.9), 62.7 (± 1.9), 56.7 (± 1.9), and 67.0 (± 1.9), respectively. The mean no load DP (± 1 S.D.) for phases 1, 2, 3 and 4 were 27.7 (±1.0), 32.2 (±1.0), 43.8 (± 1.0), and 29.4 (±1.0), respectively and for the load DP they were 19.7 (± 1.0), 26.9 (± 1.0), 31.4 (± 1.0), and 17.8 (± 1.0), respectively. CONCLUSIONS: Addition of a neurocognitive load may affect movement coordination between the hip and knee such that it is more in-phase in phases 1 and 4, and more out of phase in phases 2 and 3. The variability of this coordination appears to be lower in the loading condition across all phases. Funded by the People's United Center for Women in Business at Quinnipiac University