Increasing cognitive load attenuates right arm swing in healthy human walking

Abstract

Human arm swing looks and feels highly automated, yet it is increasingly apparent that higher centres, including the cortex, are involved in many aspects of locomotor control. The addition of a cognitive task increases arm swing asymmetry during walking, but the characteristics and mechanism of this asymmetry are unclear. We hypothesized that this effect is lateralized and a Stroop word-colour naming task—primarily involving left hemisphere structures—would reduce right arm swing only. We recorded gait in 83 healthy subjects aged 18–80 walking normally on a treadmill and while performing a congruent and incongruent Stroop task. The primary measure of arm swing asymmetry—an index based on both three-dimensional wrist trajectories in which positive values indicate proportionally smaller movements on the right—increased significantly under dual-task conditions in those aged 40–59 and further still in the over-60s, driven by reduced right arm flexion. Right arm swing attenuation appears to be the norm in humans performing a locomotor-cognitive dual-task, confirming a prominent role of the brain in locomotor behaviour. Women under 60 are surprisingly resistant to this effect, revealing unexpected gender differences atop the hierarchical chain of locomotor control.

The impact of age-related hearing loss and lateralized auditory attention on spatiotemporal parameters of gait during dual-tasking among community dwelling older adults

“…One of these studies evaluated gait asymmetries by the use of a verbal fluency test (Dalton, Sciadas, & Nantel, A C C E P T E D M A N U S C R I P T 5 2016), but data only showed a trend towards disrupted asymmetry. In another recent investigation, arm swing asymmetries in healthy older adults have been reported during execution of a dual-task employing the Stroop test (Killeen et al, 2017). Authors of this study remark the absence of information about asymmetric effects for lower limbs, implying that gait asymmetries might not arouse by dual-tasking in healthy populations.…”

Arm swing asymmetry in overground walking

“…observed treadmill walking in eight right-handed and eight left-handed individuals and reported left-dominant arm swing in both groups 16 , concluding that asymmetry is not related to handedness. Other studies of arm swing during treadmill walking included too few left-handers to confirm these findings 7 , 15 . To our knowledge, no studies have evaluated directional (i.e.…”

“…Asymmetry of arm swing during gait is often observed in Parkinson’s disease (PD) and may be present in the prodromal stage of the disorder 11 – 14 . Asymmetrical arm swing nevertheless seems to be a common feature of otherwise normal gait 7 , 15 , 16 . Interestingly, studies in healthy individuals consistently report left arm swing amplitudes greater than those on the right 7 , 15 – 17 .…”

“…Rhythmic swinging of the arms is a universal feature of human bipedal gait that appears to have a minor 1 – 4 or negligible 5 role in reducing the metabolic cost of walking and is likely subject to a mix of cortical 6 , 7 and lower-level 1 , 8 – 10 neural control. Asymmetry of arm swing during gait is often observed in Parkinson’s disease (PD) and may be present in the prodromal stage of the disorder 11 – 14 .…”

Profiling walking dysfunction in multiple sclerosis: characterisation, classification and progression over time

“…We quantified 28 key gait parameters describing leg, trunk and arm movements to comprehensively characterise walking patterns in patients and healthy controls. Gait parameters were assessed per step cycle and were classified into different functional domains: (1) limb excursion: step length, toe height at mid-swing phase, 3D path of wrist trajectory; (2) range of motion: range of motion (ROM) of hip, knee and ankle joints (leg joint angles were calculated by a 3D vector-based approach described elsewhere 86 ; (3) asymmetry: left-right asymmetry of leg joint excursion as assessed by a modified asymmetry index (ASI; see equation (1)) used elsewhere 87 , 88 : (4) instability: step width, 3D path of cervical spine (C7) marker, centre of mass (COM) movements in mediolateral (ML) and anteroposterior (AP) directions; (5) inter-limb coordination: temporal left–right coordination of legs and arms as defined by phase dispersion 89 , 90 . In a subject walking perfectly in phase, heel strike of one limb occurs precisely at the mid-point of the contralateral step cycle, resulting in a phase dispersion of 0.5.…”