Associations between trunk postural control in walking and unstable sitting at various levels of task demand

Abstract

Trunk postural control (TPC) has been investigated in several populations and tasks. Previous work observed targeted training of TPC via isolated trunk control tasks may improve performance in other activities (e.g., walking). However, the nature of this relationship remains unknown. We therefore investigated the relationship between TPC, at both the global (i.e., response to finite perturbations) and local (i.e., resistance to continuous perturbations) levels, during walking and unstable sitting, both at varying levels of task demand. Thirteen individuals (11 Male, 2 Female) with no recent history (past 12 months) of illness, injury, or musculoskeletal disorders walked on a dual-belt treadmill at four speeds (-20%, -10%, +10%, and + 20% of self-selected walking speed) and completed an unstable sitting task at four levels of chair instability (100, 75, 60, and 45% of an individual's "neutral" stability as defined by the gravitational gradient). Three-dimensional trunk and pelvic kinematics were collected. Tri-planar Lyapunov exponents and sample entropy characterized local TPC. Global TPC was characterized by ranges of motion and, for seated trials, metrics derived from center-of-pressure time series (i.e., path length, 95% confidence ellipse area, mean velocity, and RMS position). No strong or significant correlations (-0.057 < ρ < 0.206) were observed between local TPC during walking and unstable sitting tasks. However, global TPC declined in both walking and unstable sitting as task demand increased, with a moderate inter-task relationship (0.336 < ρ < 0.544). While the mechanisms regulating local TPC are inherently different, global TPC may be similarly regulated across both tasks, supporting future translation of improvements in TPC between tasks.

Dynamics of Modular Neuromotor Control of Walking and Running during Single and Dual Task Conditions

“…The increase in complexity and decreased local stability of COM motion with increasing locomotion speed are in agreement with previous findings indicating that the added 18 neuromotor challenge of faster speeds leads to less stable more complex gait (England and Granata, 2007;Mehdizadeh et al, 2014;Acasio et al, 2018;Walsh and Taylor, 2019). In addition, the decrease in local dynamic stability (i.e.…”

“…These findings are in agreement with previous studies reporting decreased stability in cognitive and motor dual tasks (Magnani et al, 2017) and those reporting changes in spatio-temporal variables such as decreased gait speed (Patel et al, 2014) and step length (Caramia et al, 2017), increased step width and step width variability (Magnani et al, 2017) in young healthy adults. The increased complexity and decreased stability reported for VT suggest that active control or constraint of COM motion was reduced in this direction (Dingwell and Marin, 2006;Acasio et al, 2018;Walsh and Taylor, 2019) resulting in greater instability. However, the lack of effect of DT in the AP and ML directions suggests these directions were more tightly controlled, or less effected, under DT conditions.…”

Trunk postural control during unstable sitting among individuals with and without low back pain: A systematic review with an individual participant data meta-analysis

“…Most studies ( n = 25/40) used an unstable seat that attached to part of a hemisphere (LBP data: n = 8 [ 19 , 22 , 30 , 31 , 33 , 35 , 73 , 74 ]; only pain-free data: n = 17 [ 21 , 25 – 28 , 77 – 80 , 85 – 90 , 92 , 93 ]). Other studies ( n = 15/40) used an unstable chair that attached to four springs moving about a pivot (LBP data: n = 7 [ 24 , 29 , 32 , 34 , 72 , 75 , 76 ]; only pain-free data: n = 8 [ 23 , 81 – 84 , 91 , 94 , 95 ]). Seat characteristics differed between studies.…”

“…For the springs-base seat, the distance of springs from the pivot in percentage ranged from 43.5–100%. Some studies ( n = 11/40) used multiple levels of seat instability [ 21 , 22 , 25 , 27 , 72 , 73 , 77 , 81 , 91 , 92 , 94 ]. Most studies ( n = 34/40) attached a foot plate to the seat to maintain knee flexion at 90° [ 19 , 21 – 24 , 26 , 28 – 35 , 72 – 86 , 89 , 91 , 93 – 95 ].…”

Cortical activity, kinematics and trunk muscles activity response to pelvis movements during unstable sitting

“…Trunk postural control is often assessed when using unstable seats to perform the sitting tasks [3]. The larger centerof-pressure while sitting on unstable seat indicates the poorer postural control [3,4]. Balance control is a leading component of human every day motor activities such as standing, walking or sitting and its impairment is associated with an increased risk of falling [5,6], functional independence [6], lower back pain due to impaired motor control mechanism.…”