Effect of blindfolding on centre of pressure variables in healthy horses during quiet standing

Abstract Background Research suggests that individuals with low back pain (LBP) may have poorer motor control compared to their healthy counterparts. However, the sample population of almost 90% of related articles are young and middle-aged people. There is still a lack of a systematic review about the balance performance of elderly people with low back pain. This study aimed to conduct a systematic review and meta-analysis to understand the effects of LBP on balance performance in elderly people. Methods This systematic review and meta-analysis included a comprehensive search of PubMed, Embase, and Cochrane Library databases for full-text articles published before January 2020. We included the articles that 1) investigated the elderly people with LBP; 2) assessed balance performance with any quantifiable clinical assessment or measurement tool and during static or dynamic activity; 3) were original research. Two independent reviewers screened the relevant articles, and disagreements were resolved by a third reviewer. Results Thirteen case-control studies comparing balance performance parameters between LBP and healthy subjects were included. The experimental group (LBP group) was associated with significantly larger area of centre of pressure movement (P < 0.001), higher velocity of centre of pressure sway in the anteroposterior and mediolateral directions (P = 0.01 and P = 0.02, respectively), longer path length in the anteroposterior direction (P < 0.001), slower walking speed (P = 0.05), and longer timed up and go test time (P = 0.004) than the control group. Conclusion The results showed that balance performance was impaired in elderly people with LBP. We should pay more attention to the balance control of elderly people with LBP.

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Response to perturbation during quiet standing resembles delayed state feedback optimized for performance and robustness

Scientific Reports ◽

10.1038/s41598-021-90305-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ambrus Zelei ◽

John Milton ◽

Gabor Stepan ◽

Tamas Insperger

Keyword(s):

State Feedback ◽

Postural Sway ◽

Fast Response ◽

Neural System ◽

Feedback Mechanism ◽

Quiet Standing ◽

Deterministic Models ◽

Measured Time ◽

Delayed State Feedback ◽

Damped Oscillator

AbstractPostural sway is a result of a complex action–reaction feedback mechanism generated by the interplay between the environment, the sensory perception, the neural system and the musculation. Postural oscillations are complex, possibly even chaotic. Therefore fitting deterministic models on measured time signals is ambiguous. Here we analyse the response to large enough perturbations during quiet standing such that the resulting responses can clearly be distinguished from the local postural sway. Measurements show that typical responses very closely resemble those of a critically damped oscillator. The recovery dynamics are modelled by an inverted pendulum subject to delayed state feedback and is described in the space of the control parameters. We hypothesize that the control gains are tuned such that (H1) the response is at the border of oscillatory and nonoscillatory motion similarly to the critically damped oscillator; (H2) the response is the fastest possible; (H3) the response is a result of a combined optimization of fast response and robustness to sensory perturbations. Parameter fitting shows that H1 and H3 are accepted while H2 is rejected. Thus, the responses of human postural balance to “large” perturbations matches a delayed feedback mechanism that is optimized for a combination of performance and robustness.

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Effects of task difficulty on centre of pressure excursion and its inter-trial variability in acrobatic gymnastics pyramid performance

Sports Biomechanics ◽

10.1080/14763141.2020.1770322 ◽

2020 ◽

pp. 1-16

Author(s):

Pureza Leal del Ojo ◽

Pablo Floría ◽

Andrew J Harrison ◽

Luis Arturo Gómez-Landero

Keyword(s):

Task Difficulty ◽

Centre Of Pressure

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‘Mammoth Vessels and Coriolis Force’

Journal of Navigation ◽

10.1017/s0373463300018774 ◽

1971 ◽

Vol 24 (2) ◽

pp. 252-253

Author(s):

G. R. G. Lewison

Keyword(s):

Northern Hemisphere ◽

Coriolis Force ◽

Forward Speed ◽

Centre Of Pressure ◽

Drift Angle ◽

Centre Of Gravity ◽

Resistive Forces ◽

Yaw Angle

Mr. Anneveld's paper (24, 50) would have us believe that the effects of coriolis force on a ship may become appreciable as ship size increases. It is true that the drift angle does increase as the ship's size increases, because the coriolis force given by equation (1) increases as (length)3·5 and the resistive forces increase as (length)3 (on the assumption of geometrically similar ships and Froude scaling). However there is a fundamental flaw in his argument because equation (2) only applies to a vessel with zero forward speed. Moreover the effect of coriolis drift will also be to induce a yaw angle on the ship (because the centre of pressure is forward of the centre of gravity, where the coriolis force may be assumed to act) and this will automatically cause the helmsman or autopilot to apply starboard rudder in the northern hemisphere. This will immediately produce a force on the ship in the port direction, i.e. opposing coriolis force.

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