Biology subjects

Buurke, T. J. W.

Publications and source records attributed to Buurke, T. J. W..

4 recordsLinked to original sources

bioRxiv2025

The Effect of Physical Activity Level on Age-Related Differences in Responses to Optic Flow Perturbation during Human Walking

BackgroundHuman aging increases the reliance on vision for walking balance due to age-related declines in proprioceptive and vestibular function. Regular physical activity (PA) may reduce the reliance on visual input during walking. This study examined whether PA levels modulate age-related responses to perturbations of the optic flow that is crucial in the control of human locomotion. MethodsSixty active and inactive younger (YA and YI: 23.3{+/-}3.91 y) and older adults (OA and OI: 68.3{+/-}3.98 y; n=15 for each group) walked on a treadmill in front of a virtual hallway. The walking protocol consisted of 3-minute walking without, and 8-minute with mediolateral optic flow perturbation. Sacrum and heel marker positions and ground reaction forces were recorded. Power spectral density (PSD) of the mediolateral sacrum position and gait parameters were analyzed. ResultsThe PSD increased more in OA compared to OI adults (p=0.041) while YA and YI adults did not differ. Mean (and variability of) step width and mediolateral margin of stability increased irrespective of age and PA (all p<0.001). During the 8-minute perturbation, OA adults demonstrated greater decreases in PSD than the OI adults (p=0.039). Additionally, the variability in the mediolateral margin of stability reduced more in YA and OA adults compared to YI and OI adults (p=0.048). ConclusionHigher PA levels in OA adults were associated with stronger immediate responses in body sway to optic flow perturbations compared to older inactive and younger adults. This may support the beneficial effects of physical activity on age-related visual dependency during gait.

neuroscience↗

bioRxiv2025

The effects of gait speed on the responses to immediate and prolonged exposure to mediolateral optic flow perturbation in healthy young adults

BackgroundOptic flow is vital for locomotor control and is often perturbed to study the impact of optic flow on balance control. However, it remains unclear whether gait speed influences responses to such perturbations. This study aims to examine the effects of gait speed on gait parameters following immediate and prolonged exposure to mediolateral optic flow perturbations. MethodsTwenty-one young adults (23.43 {+/-} 4.19 years) walked on an instrumented treadmill, including 3 phases: baseline (3 min), perturbation with mediolateral optic flow (8 min), and post-perturbation (3 min). Trials were conducted at 0.6, 1.2, and 1.8 m/s. Ground reaction forces and 3D motion data were collected to calculate mediolateral margin of stability (MoS), mean step length (SL), step width (SW) and their variabilities. Three repeated-measures ANOVAs (Speed by Phase) were used to compare: baseline vs. early perturbation, early vs. late perturbation, and baseline vs. post-perturbation. ResultsThe responses to immediate and prolonged exposure to optic flow perturbation were speed dependent. Walking at slow speeds induced greater immediate responses in mediolateral gait parameters (SW and mediolateral MoS, both p < 0.001) compared to walking at faster speeds. During the perturbation phase, the adaptations were larger at faster vs. slower speeds for gait parameters in the direction of movement (SL, p = 0.007). ConclusionImmediate responses and adaptations to mediolateral optic flow perturbations are speed-dependent and larger at slower gait speeds. The responses to prolonged perturbation are interpreted as step-to-step adaptations that may inform future interventions and studies on gait speed selection.

neuroscience↗

bioRxiv2024

Quadriceps-hamstrings muscle co-activation during the swing phase of walking is modulated by task constraints in healthy adults

BackgroundMuscle co-activation, the simultaneous activation of muscles or muscle groups, is a common strategy to enhance the stability of the musculoskeletal system. However, co-activation can also be the consequence of underlying neurological impairments. To better understand and discern functional co-activation during walking, this study explored the difference in quadriceps-hamstrings co-activation during the swing phase of walking and an isolated leg-swinging movement in healthy adults. MethodsTwelve healthy young adults performed walking and isolated leg-swinging at slow (0.6 m/s) and comfortable speed. Isolated leg-swinging was frequency and amplitude matched to the walk conditions. Electromyography signals from m. vastus lateralis, m. rectus femoris, m. biceps femoris, and m. semitendinosus were recorded. Pearson correlation coefficient (Pearson-CI) was calculated as a measure of rate of co-activation. Area under the curve (AUC-CI) was calculated as a measure of co-activation magnitude. Co-activation indices were calculated for both metric across the four muscle pairs and averaged into a single quadriceps-hamstrings CI for each metric. ResultsThe results showed a higher Pearson-CI, but not AUC-CI, during walking compared to isolated leg-swinging, specifically during mid- and terminal-swing at both speeds. AUC-CI, but not Pearson-CI, was significantly higher during slow speed, compared to comfortable speed. ConclusionQuadriceps-hamstrings co-activation towards the end of the swing phase during walking reflects preparation for heel-strike, which is not present in isolated leg-swinging. Therefore, an isolated leg-swinging task could serve as a feasible method to distinguish pathological from functional muscle co-activation during walking.

neuroscience↗

bioRxiv2022

The effect of walking with reduced trunk motion on dynamic stability in healthy adults

BackgroundMost people with Parkinsons Disease (PD) walk with a smaller mediolateral base of support (BoS) compared to healthy people, but the underlying mechanisms remain unknown. According to the extrapolated center of mass (XCoM) concept, a decrease in mediolateral XCoM excursion would require a smaller mediolateral BoS to maintain a constant margin of stability (MoS) and remain stable. As people with PD typically walk with reduced trunk motion, we hypothesized that the mediolateral MoS might stay the same despite a smaller BoS. Research questionAs proof of principle, we assess whether walking with reduced trunk motion results in a smaller step width in healthy adults, without altering the mediolateral MoS. MethodsFifteen healthy adults walked on a treadmill at preferred comfortable walking speed in two conditions. First, the regular walking condition without any instructions, and second, the reduced trunk motion condition with the instruction: Keep your trunk as still as possible. Treadmill speed was kept the same in the two conditions. Trunk kinematics, step width, mediolateral XCoM excursion and mediolateral MoS were calculated and compared between the two conditions. ResultsWalking with the instruction to keep the trunk still significantly reduced trunk kinematics. Walking with reduced trunk motion resulted in significant decreases in step width and mediolateral XCoM excursion, but not in the mediolateral MoS. Furthermore, step width and mediolateral XCoM excursion were strongly correlated during both conditions (r=0.887 and r=0.934). SignificanceThis study shows that walking with reduced trunk motion leads to a gait pattern with a smaller BoS in healthy adults, without altering the mediolateral MoS. Our findings indicate a strong coupling between CoM motion state and the mediolateral BoS. We expect that people with PD who walk narrow-based, have a similar mediolateral MoS as healthy people, which will be further investigated.

neuroscience↗