scholarly journals The Effect of Fatigue on Single-Leg Postural Sway and Its Transient Characteristics in Healthy Young Adults

2021 ◽  
Vol 12 ◽  
Author(s):  
Žiga Kozinc ◽  
Nebojša Trajković ◽  
Darjan Smajla ◽  
Nejc Šarabon

Neuromuscular fatigue is known to impair balance ability, which is reflected in increased postural sway during quiet standing tasks. Recently, quantifying transient characteristics of postural sway has been suggested as an approach to obtain additional information regarding postural control. However, this approach is currently vastly unexplored. The purpose of this study was to investigate the effects of fatigue (induced by a repeated change of direction task) on postural sway and its transient characteristics during single-leg standing, including whole-trial estimates and indexes of transient behavior in young healthy active adults. The study involved 28 physically active students (14 females). Single-leg postural sway was recorded for 30s before and after a fatiguing protocol, which consisted of a repeated change of direction tasks. We calculated the traditional whole-trial estimates of postural sway [center-of-pressure (CoP) velocity and amplitude in anterior-posterior (AP) and medial-lateral (ML) directions] and corresponding transient behavior indexes, based on three 10-s intervals. Statistically significant sex×fatigue interaction with medium effect sizes was found for whole-trial CoP velocity in AP (p=0.028; η2=0.17) and ML directions (p=0.019; η2=0.19). Post-hoc test showed that both variables substantially decreased in female participants (p=0.041–0.045; d=0.54–0.56), but remained similar in males (p=0.194–0.294). There were small to medium statistically significant main effects of fatigue on transient index for CoP amplitude in both directions (p=0.042–0.049; η2=0.02–0.14). Notably, CoP AP amplitude increased in the first 10-s interval for males (before fatigue: 5.6±1.3mm; after fatigue: 6.3±1.6mm), while the CoP AP amplitude in the third interval remained similar after fatigue (before fatigue: 5.5±1.4mm; after fatigue: 5.1±1.2mm). In conclusion, the responses to fatigue in terms of postural sway were time interval specific, and there were certain sex-differences in responses to fatigue, which could be related to better ability to adapt balance strategies in females. Moreover, our results demonstrate that the indexes of transient behavior could perhaps detect smaller fatigue-induced changes in postural sway that are seen in whole-trial estimates.

2011 ◽  
Vol 20 (4) ◽  
pp. 442-456 ◽  
Author(s):  
Zohreh Meshkati ◽  
Mehdi Namazizadeh ◽  
Mahyar Salavati ◽  
Masood Mazaheri

Context:Although reliability is a population-specific property, few studies have investigated the measurement error associated with force-platform parameters in athletic populations.Objective:To investigate the skill-related differences between athletes and nonathletes in reliability of center-of-pressure (COP) summary measures under eyes-open (EO) and eyes-closed (EC) conditions.Design:Test–retest reliability study.Setting:COP was recorded during double-leg quiet standing on a Kistler force platform before and after a fatiguing treadmill exercise, with EO and EC.Participants:31 male participants including 15 athletes practiced in karate and 16 nonathletes.Main Outcome Measures:Standard deviation (SD) of amplitude, phase-plane portrait, SD of velocity, mean total velocity, and area were calculated from 30-s COP data. Intraclass correlation coefficient (ICC), standard error of measurement, and coefficient of variation (CV) were used as estimates of reliability and precision.Results:Higher ICCs were found for COP measures in the athlete (compared with the nonathlete) group, postfatigued (compared with prefatigued) condition, and EC (compared with EO) tests. CVs smaller than 15% were obtained for most of the COP measures. SD of velocity in the anteroposterior direction showed the highest reliability in most conditions.Conclusions:Tests with EC and to a lesser extent tests performed in the athlete group and in the postfatigued condition showed better reliability.


2013 ◽  
Vol 29 (1) ◽  
pp. 44-48 ◽  
Author(s):  
Paulo H. Marchetti ◽  
Maria I.V. Orselli ◽  
Marcos Duarte

The aim of this study was to investigate the effects of unilateral and bilateral fatigue on both postural and power bipedal tasks. Ten healthy subjects performed two tasks: bipedal quiet standing and a maximal bipedal counter-movement jumping before and after unilateral (with either the dominant or nondominant lower limb) and bilateral (with both lower limbs) fatigue. We employed two force plates (one under each lower limb) to measure the ground reaction forces and center of pressure produced by subjects during the tasks. To quantify the postural sway during quiet standing, we calculated the resultant center of pressure (COP) speed and COP area of sway, as well as the mean weight distribution between lower limbs. To quantify the performance during the countermovement jumping, we calculated the jump height and the peak force of each lower limb. We observed that both unilateral and bilateral fatigue affected the performance of maximal voluntary jumping and standing tasks and that the effects of unilateral and bilateral fatigue were stronger in the dominant limb than in the nondominant limb during bipedal tasks. We conclude that unilateral neuromuscular fatigue affects both postural and power tasks negatively.


2021 ◽  
Vol 14 ◽  
Author(s):  
Žiga Kozinc ◽  
Nejc Šarabon

Instrumented assessments of quiet-stance postural control typically involve recording and analyzing of body sway signal, most often the center of pressure (CoP) movement. It has been recently suggested that transient characteristics of body sway may offer additional information regarding postural control. In this study, we explored the relationship between whole-trial estimates of body sway (CoP velocity, amplitude, and frequency) and corresponding transient behavior indexes, as well as the effects of leg preference. A total of 705 healthy young athletes performed 30 s single-leg body sway trials for both legs. It was found that the transient characteristics of the body sway (expressed as relative differences between individual time intervals within the trial) are in negligible or weak correlation (r ≤ 0.26) with the corresponding variables, averaged across the whole trial. All CoP variables showed transient characteristics, reflected in statistically significant decrease (CoP velocity and amplitude) or increase (CoP frequency) throughout the trial. The preferred leg showed smaller body sway; however, the effect sizes were very small. Moreover, differences between the legs were also noted in terms of transient characteristics of body sway. In particular, the preferred leg showed earlier reduction in anterior–posterior body sway and larger reduction in medial–lateral body sway. Further studies should focus on examining the clinical utility of indexes of transient behavior of body sway, for instance, their sensitivity to aging-related changes and risk of falling.


Author(s):  
Elżbieta Piątek ◽  
Michał Kuczyński ◽  
Bożena Ostrowska

Due to balance deficits that accompany adolescent idiopathic scoliosis (AIS), the potential interaction between activities of daily living and active self-correction movements (ASC) on postural control deserves particular attention. Our purpose was to assess the effects of ASC movements with or without a secondary mental task on postural control in twenty-five girls with AIS. It is a quasi-experimental within-subject design with repeated measures ANOVA. They were measured in four 20-s quiet standing trials on a force plate: no task, ASC, Stroop test, and both. Based on the center-of-pressure (COP) recordings, the COP parameters were computed. The ASC alone had no effect on any of the postural sway measures. Stroop test alone decreased COP speed and increased COP entropy. Performing the ASC movements and Stroop test together increased the COP speed and decreased COP entropy as compared to the baseline data. In conclusion, our results indicate that AIS did not interfere with postural control. The effects of the Stroop test accounted for good capacity of subjects with AIS to take advantage of distracting attentional resources from the posture. However, performing both tasks together exhibited some deficits in postural control, which may suggest the need for therapeutic consultation while engaging in more demanding activities.


Motor Control ◽  
2020 ◽  
Vol 24 (1) ◽  
pp. 91-112
Author(s):  
Fatemeh Azadinia ◽  
Ismail Ebrahimi-Takamjani ◽  
Mojtaba Kamyab ◽  
Morteza Asgari ◽  
Mohamad Parnianpour

The characteristics of postural sway were assessed in quiet standing under three different postural task conditions in 14 patients with nonspecific chronic low back pain and 12 healthy subjects using linear and nonlinear center of pressure parameters. The linear parameters consisted of area, the mean total velocity, sway amplitude, the SD of velocity, and the phase plane portrait. The nonlinear parameters included the Lyapunov exponent, sample entropy, and the correlation dimension. The results showed that the amount of postural sway was higher in the patients with low back pain compared with the healthy subjects. Assessing the nonlinear parameters of the center of pressure showed a lower sample entropy and a higher correlation dimension in the patients with low back pain compared with the healthy subjects. The results of this study demonstrate the greater regularity and higher dimensionality of the center of pressure fluctuations in patients with nonspecific chronic low back pain, which suggests that these patients adopt different postural control strategies to maintain an upright stance.


2021 ◽  
Vol In Press (In Press) ◽  
Author(s):  
Zahra Ahmadizadeh ◽  
Atefeh Aminianfar ◽  
Karim Ayoubi

Background: Kinesio-Tape (KT) is a common method used in rehabilitation, but the KT short-term therapeutic effects on children with cerebral palsy (CP) are unclear yet. Objectives: This study aims to investigate the short-term and immediate effects of KT on postural sway in children with CP. Methods: In this before- and after-study, 27 children aged between 4 and 11 years old with spastic CP were included. Immediate and short-term effects of KT on Quadriceps muscle (QcM) were then assessed using time-up and go test (TUG) and COP (center of pressure) displacement in five assessments. Results: The results of Repeated Measure Analysis show that the short-term use of KT on QcM could reduce COP displacement in both the mediolateral and anteroposterior directions and improve the balance among children with CP (P < 0.05). Conclusions: The immediate effects of KT on the QcM did not change the COP’s displacement and balance. It was demonstrated that the short-term use of KT in QcM could improve the balance of COP and reduce its displacement.


2008 ◽  
Vol 104 (5) ◽  
pp. 1359-1365 ◽  
Author(s):  
Craig D. Tokuno ◽  
S. Jayne Garland ◽  
Mark G. Carpenter ◽  
Alf Thorstensson ◽  
Andrew G. Cresswell

Previous research has shown that changes in spinal excitability occur during the postural sway of quiet standing. In the present study, it was of interest to examine the independent effects of sway position and sway direction on the efficacy of the triceps surae Ia pathway, as reflected by the Hoffman (H)-reflex amplitude, during standing. Eighteen participants, tested under two different experimental protocols, stood quietly on a force platform. Percutaneous electrical stimulation was applied to the posterior tibial nerve when the position and direction of anteroposterior (A-P) center of pressure (COP) signal satisfied the criteria for the various experimental conditions. It was found that, regardless of sway position, a larger amplitude of the triceps surae H-reflex (difference of 9–14%; P = 0.005) occurred when subjects were swaying in the forward compared with the backward direction. The effects of sway position, independent of the sway direction, on spinal excitability exhibited a trend ( P = 0.075), with an 8.9 ± 3.7% increase in the H-reflex amplitude occurring when subjects were in a more forward position. The observed changes to the efficacy of the Ia pathway cannot be attributed to changes in stimulus intensity, as indicated by a constant M-wave amplitude, or to the small changes in the level of background electromyographic activity. One explanation for the changes in reflex excitability with respect to the postural sway of standing is that the neural modulation may be related to the small lengthening and shortening contractions occurring in the muscles of the triceps surae.


Author(s):  
Tyler Grey ◽  
Daren Redguard ◽  
Rebecca Wengle ◽  
Peter Wegscheider

Objective. Previous studies have demonstrated that various factors alter postural stability. Our aim was to examine the effect of plantar flexor fatigue on postural stability in quiet standing. Methods. Fifteen healthy male university students (age, 21.3 ± 1.7y; height, 1.83 ± 0.06m; weight, 81.6 ± 9.4kg) were instructed to stand on a force plate before and after calf fatiguing exercise. The sensory systems were controlled by blindfolding subjects and having them stand on a flat firm surface, without moving their head. Fatigue was achieved through repetitive weighted plantar-flexor exercise. Standing balance was assessed by using a force plate to calculate Center of Pressure (CoP) displacement. Results. Plantar flexor fatigue led to significant (p


2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Anelise Sonza ◽  
Caroline C. Robinson ◽  
Matilde Achaval ◽  
Milton A. Zaro

The aim of this study was to investigate the effects of whole body vibration (WBV) on physiological parameters, cutaneous temperature, tactile sensitivity, and balance. Twenty-four healthy adults (25.3±2.6years) participated in four WBV sessions. They spent 15 minutes on a vibration platform in the vertical mode at four different frequencies (31, 35, 40, and 44 Hz) with 1 mm of amplitude. All variables were measured before and after WBV exposure. Pressure sensation in five anatomical regions and both feet was determined using Von Frey monofilaments. Postural sway was measured using a force plate. Cutaneous temperature was obtained with an infrared camera. WBV influences the discharge of the skin touch-pressure receptors, decreasing sensitivity at all measured frequencies and foot regions (P≤0.05). Regarding balance, no differences were found after 20 minutes of WBV at frequencies of 31 and 35 Hz. At 40 and 44 Hz, participants showed higher anterior-posterior center of pressure (COP) velocity and length. The cutaneous temperature of the lower limbs decreased during and 10 minutes after WBV. WBV decreases touch-pressure sensitivity at all measured frequencies 10 min after exposure. This may be related to the impaired balance at higher frequencies since these variables have a role in maintaining postural stability. Vasoconstriction might explain the decreased lower limb temperature.


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