DOI: 10.5061/dryad.bnzs7h4ds
title: Kinematic and neuromuscular characterization of cognitive involvement in gait control in healthy young adults

description: The signature of cognitive involvement in gait control has rarely been
 studied using both kinematic and neuromuscular features. The present study
 aimed to address this gap. Twenty-four healthy young adults walked on an
 instrumented treadmill in a virtual environment under two optic flow
 conditions: normal (NOF) and perturbed (POF, continuous mediolateral
 pseudorandom oscillations). Each condition was performed under single-task
 and dual-task conditions of increasing difficulty (1-, 2-, 3-back).
 Subjective mental workload (raw NASA-TLX), cognitive performance (mean
 reaction time and d-prime), kinematic (steadiness, variability and
 complexity in the mediolateral and anteroposterior directions) and
 neuromuscular (duration and variability of motor primitives) control of
 gait were assessed. The cognitive performance and the number and
 composition of motor modules were unaffected by simultaneous walking,
 regardless of the optic flow condition. Kinematic and neuromuscular
 variability was greater under POF compared to NOF conditions. Young adults
 sought to counteract POF by rapidly correcting task-relevant gait
 fluctuations. The depletion of cognitive resources through dual-tasking
 led to reduced kinematic and neuromuscular variability and this occurred
 to the same extent regardless of simultaneous working memory (WM) load.
 Increasing WM load led to a prioritization of gait control in the
 mediolateral direction over the anteroposterior direction. The impact of
 POF on kinematic variability (step velocity) was reduced when a cognitive
 task was performed simultaneously, but this phenomenon was no modulated by
 WM load. Collectively, these results shed important light on how young
 adults adjust the processes involved in goal-directed locomotion when
 exposed to varying levels of task and environmental constraints.
description: Subjects: Healthy young adults,
 kinematic data: N = 24, 12 men and 12 women, age = 21.67 +/- 2.28 years
 old. Healthy young adults, EMG data: N = 20, 10 men
 and 10 women, age = 21.80 +/- 2.42 years old. 
 The testing session was composed of three blocks performed in a
 randomised order: (1) three N-back tasks in a seated position (single-task
 cognitive performance, STC), (2) walking under normal (congruent) optic
 flow (NOF), and (3) walking under perturbed (continuous mediolateral
 pseudo-random oscillations) optic flow (POF). In the latter two blocks,
 the walking tasks were performed under both single-task (STW) and
 dual-task (DTW) conditions (i.e. walking while performing the N-back
 tasks). Participants were asked to walk naturally while looking straight
 ahead. The treadmill speed was adjusted to their preferred walking speed.
 The blocks (2) and (3) began and ended with a STW condition while the
 three DTW conditions were performed in a randomized order between the two
 STW conditions (Schaefer et al., 2015). Under dual-task conditions, no
 task priority instructions were given (Schaefer et al., 2015). Each
 condition lasted for 3 minutes. Hence, a total of thirteen experimental
 conditions were performed. "STC"
 = Single-task cognitive performance; "STW"
 = Single-task walking; "DTW" = Dual-task
 walking; "NOF" = Normal optic
 flow; "POF" = Perturbed optic
 flow; "1b" = 1-back task;
 "2b" = 2-back task;
 "3b" = 3-back task. 
 [See paper for exact definitions / descriptions]
 Foot placement kinematics (200 Hz) and surface electromyography
 (EMG) of soleus and gluteus medius (1000 Hz) were recorded. For kinematic
 variables, mean, standard deviation (variability), statistical persistence
 and step-to-step error correction were computed from gait time series in
 mediolateral and anteroposterior directions. For EMG variables, duration
 and variability of muscle activation were calculated from the full width
 at half maximum (FWHM) and the variance ratio, respectively. Performance
 on N-back tasks was assessed with mean reaction time for target trials
 (RT, in second) and d-prime (d’, a.u.).
description: The dataset is composed of 5 files as follows:
 1 text file (README_All-files.txt) which contains
 information about the database and how the files are organized;
 1 Microsoft Office Excel spreadsheet
 (Cognition_All-participants.xlsx) which contains the results of the N-back
 task for each experimental condition;  1 Microsoft
 Office Excel spreadsheet (RAW-NASA-TLX_All-participants.xlsx) which
 contains the results of the NASA-TLX questionnaire on perceived cognitive
 load for each experimental condition; 1 Microsoft
 Office Excel spreadsheet (Gait_All-participants.xlsx) which contains the
 results of the kinematic and electromyography analysis for each
 experimental condition;  1 zip file
 (Gait-parameters.zip) which contains: 1 text file
 (README_Gait-parameters.txt) which contains information about the gait
 parameters available in each of the 24 *.csv files;
 24 comma-separated value files (P01 to P24.csv) which contain
 the kinematic and EMG time series for each experimental
 condition. Excel
 spreadsheets and *.csv files could be opened using open source
 alternatives such as LibreOffice (Calc). Contact:
 Leslie M. DECKER, Associate Professor (PhD, HDR), Université de Caen
 Normandie (France): leslie.decker@unicaen.fr
description: # Kinematic and neuromuscular characterization of cognitive involvement in
 gait control in healthy young adults
 [https://doi.org/10.5061/dryad.bnzs7h4ds](https://doi.org/10.5061/dryad.bnzs7h4ds) ## Description of the data and file structure Subjects: * Healthy young adults, kinematic data: N = 24, 12 men and 12 women, age = 21.67 +/- 2.28 years old. * Healthy young adults, EMG data: N = 20, 10 men and 10 women, age = 21.80 +/- 2.42 years old. The testing session was composed of three blocks performed in a randomised order: (1) three N-back tasks in a seated position (single-task cognitive performance, STC), (2) walking under normal (congruent) optic flow (NOF), and (3) walking under perturbed (continuous mediolateral pseudo-random oscillations) optic flow (POF). In the latter two blocks, the walking tasks were performed under both single-task (STW) and dual-task (DTW) conditions (i.e. walking while performing the N-back tasks). Participants were asked to walk naturally while looking straight ahead. The treadmill speed was adjusted to their preferred walking speed. The blocks (2) and (3) began and ended with a STW condition while the three DTW conditions were performed in a randomized order between the two STW conditions (Schaefer et al., 2015). Under dual-task conditions, no task priority instructions were given (Schaefer et al., 2015). Each condition lasted for 3 minutes. Hence, a total of thirteen experimental conditions were performed. * "STC" = Single-task cognitive performance; * "STW" = Single-task walking; * "DTW" = Dual-task walking; * "NOF" = Normal optic flow; * "POF" = Perturbed optic flow; * "1b" = 1-back task; * "2b" = 2-back task; * "3b" = 3-back task. \[See paper for exact definitions / descriptions] Foot placement kinematics (200 Hz) and surface electromyography (EMG) of soleus and gluteus medius (1000 Hz) were recorded. For kinematic variables, mean, standard deviation (variability), statistical persistence and step-to-step error correction were computed from gait time series in mediolateral and anteroposterior directions. For EMG variables, duration and variability of muscle activation were calculated from the full width at half maximum (FWHM) and the variance ratio, respectively. Performance on N-back tasks was assessed with mean reaction time for target trials (RT, in second) and d-prime (d’, a.u.). ### Files and variables #### File: README\_All-files.txt **Description:** contains information about the database and how the files are organized. #### File: Cognition\_All-participants.xlsx **Description:** contains the results of the N-back task for each experimental condition. ##### Variables * ``` Col A = Participant ``` * Col B = Condition * Col C = Targets (/30) * Col D = Hits (/30) * Col E = Omissions (/30) * Col F = False alarms (/60) * Col G = D-prime (a.u., Haatveit et al., 2010) * Col H = Mean reaction time (s) #### File: RAW-NASA-TLX\_All-participants.xlsx **Description:** contains the results of the NASA-TLX questionnaire on perceived cognitive load for each experimental condition. ##### Variables * Col A = Participant * Col B = Condition * Col C = Mental demand (/100) * Col D = Physical demand (/100) * Col E = Temporal demand (/100) * Col F = Performance (/100) * Col G = Effort (/100) * Col H = Frustration level (/100) * Col I = Final score, i.e., average of the previous 6 items (/100) #### File: Gait\_All-participants.xlsx **Description:** contains the results of the kinematic and electromyography analysis for each experimental condition. ##### Variables * ``` Col A = Participant ``` * Col B = Condition * Col C to Col G = Mean (m); SD - σ (m); DFA - α (a.u.); Slope - M (a.u.); R² (a.u.) of step width (W) * Col H to Col L = Mean (m); SD - σ (m); DFA - α (a.u.); Slope - M (a.u.); R² (a.u.) of lateral body position (zB) * Col M to Col Q = Mean (m); SD - σ (m); DFA - α (a.u.); Slope - M (a.u.); R² (a.u.) of step velocity (V) * Col R to Col S = Variance ratio - VR (a.u.); Full width at half maximum - FWHM (% cycle) of motor primitive 1 * Col T to Col U = Variance ratio - VR (a.u.); Full width at half maximum - FWHM (% cycle) of motor primitive 2 * Col V to Col W = Variance ratio - VR (a.u.); Full width at half maximum - FWHM (% cycle) of motor primitive 3 * Col X to Col Y = Variance ratio - VR (a.u.); Full width at half maximum - FWHM (% cycle) of motor primitive 4 #### File: Gait-parameters.zip **Description:** contains 1 text file (README_Gait-parameters.txt) which contains information about the gait parameters available in each of the 24 *.csv files, and 24 comma-separated value files (P01 to P24.csv) which contain the kinematic and EMG time series for each experimental condition. Changes made since the previously published version: Addition of the “Supplementary materials” file (uploaded to Zenodo)