Balance Performance as Observed by Center-of-Pressure Parameter Characteristics in Male Soccer Athletes and Non-Athletes

The effects of six weeks of combined balance and plyometric training on postural control performance in elite badminton players: A pilot randomized, controlled study

Background/Objectives

The athletic performance in badminton players largely depends on the capability of dynamic postural control to quickly restore balance when performing high-paced movements (e.g., frequent single-leg jumps). Our aim was to examine the effects of a novel intervention that combines balance training on an unstable surface and plyometric training on the performance of restoring balance after jumping, as well as related postural control in elite badminton players.

Methods

Sixteen elite male badminton players were randomly allocated to either a combined balance and plyometric training group (CT, n = 8) or a plyometric training group (PT, n = 8). The CT group participated in a six-week training program, which included three training sessions per week. Each session comprised 40 min of plyometric exercises and 20 min of balance training. The PT group underwent plyometric training using the identical protocol as that of the CT group. All participants underwent identical technical training in badminton throughout the duration of the study. At baseline and immediately after the intervention, participants completed a single-leg jumping test. The capacity to restore balance was evaluated using the time to stabilization (TTS) after landing; and the related center of pressure (COP) fluctuations were also recorded. The effect of intervention was examined by two-way repeated-measures of ANOVA.

Results

The primary two-way repeated-measures ANOVA models showed no significant interactions between group and time on either the time to stability in the dominant leg (D-TTS) or the time to stability in the non-dominant leg (N-TTS) (p > 0.70). Significant main effects of time, group, and their interactions on dominant legs of the anterior-posterior displacement difference (D-COPAP) (time: p = 0.001; group: p = 0.001; interaction: p = 0.014), non-dominant legs of the anterior-posterior displacement difference (N-COPAP) (time: p < 0.001; group: p = 0.003; interaction: p = 0.021) and non-dominant legs of the medial-lateral displacement difference (N-COPML) (time: p < 0.001; group: p < 0.001; interaction: p = 0.026), that is, compared to baseline of both groups and post PT, the COP metrics were significantly reduced after CT. Secondarily, within the CT and PT group, after the intervention, the N-TTS (CT: p = 0.001, post: 0.58 ± 0.87; PT: p = 0.03, post: 0.71 ± 0.11) was significantly decreased compared to baseline (CT pre: 0.76 ± 0.16; PT pre: 0.88 ± 0.13).

Conclusion

This pilot study demonstrated that, compared to PT-only, the 6-week CT which combines balance training induced comparable improvements in the capacity to restoring balance after landing from a single-leg jump, and significantly improved the postural control performance as measured by COP metrics.

Center of Pressure Velocity and Dynamic Postural Control Strategies Vary During Y-Balance and Star Excursion Balance Testing

Background

Dynamic postural control (DPC) describes an individual's ability to maintain balance within their base of support in both anticipatory and reactive balance situations and has been measured using center of pressure (COP) velocity. Common standardized DPC assessments for active adults include the modified Star Excursion Balance Test (MSEBT) and the Y-Balance Test (YBT).

Hypothesis/Purpose

The purpose of this study was to explore DPC during performance of the MSEBT, the YBT, and a modified version of the YBT, the MYBT. It was hypothesized that feedback from the YBT/MYBT reach indicator would enhance DPC.

Study Design

Cross-sectional study.

Methods

Twenty-one participants (9 females, 12 males, mean age 24.5±1.2 years) performed three trials in each direction (anterior-AN, posteromedial-PM, and posterolateral-PL) on each balance test during one session. The YBT frame was placed atop a force plate for all testing. Frontal and sagittal plane COP velocities (COPx and COPy, respectively) were recorded throughout each trial and resultant COP (COPr) velocities were calculated.

Results

Significant main effects were present for test (F=4.485, p\<0.001) and reach direction (F=61.594, p\<0.001). Post hoc analyses for test indicated significant differences in COPy between YBT and MSEBT (p=0.034) and between MYBT and MSEBT (p\<0.001), as well as significant differences in COPr between MYBT and MSEBT (p=0.002). Post hoc analyses for reach direction revealed significant differences in COPx between AN and both PM (p\<0.001) and PL (p\<0.001) directions, in COPy between AN and PM (p\<0.001) and PL (p\<0.001) directions, and COPr between AN and PL (p=0.043) directions only.

Conclusion

External proprioceptive feedback from the reach indicator improved DPC during the YBT and MYBT when compared to the MSEBT. Sagittal plane COP velocities were reduced when external proprioceptive feedback from the reach indicator was present, while frontal plane COP velocities were not affected in this group of participants.

Level of Evidence

2b.

The impact of additional visual tasks in physical exercise on balance ability among 9-10-year-old children: the mediating effect of visual acuity

Purpose

This study aimed to explore the effects of additional visual tasks in physical exercise on the vision and balance ability of children, and to verify whether children's vision mediated the influence of physical exercise on their balance ability.

Methods

The study randomly selected 86 students aged 9-10 years old from a school in Suzhou city, dividing them into an experimental group (n = 43) and a control group (n = 43). The experimental group participated in physical exercise with additional visual tasks, while the control group engaged in routine physical exercise. The experiment lasted for 16 weeks, with kinetic visual acuity (KVA), uncorrected distance visual acuity (UDVA), static balance, and dynamic balance measured before and after the experiment.

Results

The results showed that after the experiment, the experimental group had significantly improved kinetic visual acuity (KVA), uncorrected distance visual acuity (UDVA), static balance, and dynamic balance. In contrast, the control group had significantly decreased kinetic visual acuity, no significant improvement in uncorrected distance visual acuity, and no significant difference in dynamic balance and static balance. In the experimental group, there was a moderate positive correlation between kinetic visual acuity and uncorrected distance visual acuity, and a moderate positive correlation between uncorrected distance visual acuity and both static and dynamic balance. The study also found that uncorrected distance visual acuity partially mediated the effect of additional visual tasks during physical exercise on static and dynamic balance among children.

Conclusion

In conclusion, adding visual tasks to physical exercise had a positive effect on improving children's vision and balance ability. Kinetic visual acuity and uncorrected distance visual acuity were positively correlated, and uncorrected distance visual acuity was positively correlated with both static and dynamic balance. Uncorrected distance visual acuity partially mediated the effect of physical exercise on children's balance ability.

Dynamic postural control in women athletes with and without nonspecific low back pain with high and low pain-related anxiety- A case-control study

BACKGROUND

Low back pain is common among athletes and it has been shown that postural control is altered in the general population with nonspecific low back pain (NSLBP). Psychological factors may also predispose individuals to risk of altered postural control. Dynamic postural control is essential to the performance of athletes. This study aimed to compare the dynamic postural control between women athletes with and without NSLBP with high and low pain-related anxiety.

METHODS

Forty-five female athletes (15 NSLBP with high pain-related anxiety, 15 NSLBP with low pain-related anxiety, and 15 healthy (control)) were included. Pain-related anxiety was assessed using the Pain Anxiety Symptom Scale-20 (PASS-20). Based on the cut-off score of 30 for the total score of PASS-20, NSLBP patients were classified into two groups of low and high pain-related anxiety. Participants performed double-leg vertical drop jump (DVJ) and single-leg vertical jump (SVJ) tests on a Kistler force plate (type 9260AA6, Kistler Instruments Inc, Switzerland). The total root mean square (RMS) of the center of pressure (COP), COP displacement in the anteroposterior (AP), and mediolateral (ML) directions, COP mean velocity, and time to stabilization (TTS) in vertical, AP, and total directions were extracted from COP and ground reaction force data using MATLAB software. One-way Analysis of variance (ANOVA) and Welch's ANOVA were employed to compare the groups. In case of significant findings, post hoc tests were performed.

RESULTS

The results showed that during DJV, athletes with high pain-related anxiety had significantly greater TTS in all total, AP, and ML directions than other groups (P < 0.05). Also, the control group showed greater total RMS distance during DJV than either NSLBP group. However, no significant differences in TTS and COP parameters were found between the groups during SVJ (P > 0.05).

CONCLUSIONS

The findings suggest that pain-related anxiety may contribute to athletes' postural control strategies. Therefore, it is important to consider the level of pain-related anxiety during planning postural control exercises for women athletes with NSLBP.

Visual Cues for a Steadier You: Visual Feedback Methods Improved Standing Balance in Virtual Reality for People with Balance Impairments

Users of head-mounted displays (HMDs) for virtual reality (VR) sometimes have balance issues since HMDs impede their view of the outside world. This has a greater impact on people with balance impairments since many rely more heavily on their visual cues to keep their balance. This is a significant obstacle to the universal usability and accessibility of VR. Although previous studies have verified the imbalance issue, not much work has been done to diminish it. In this study, we investigated how to increase VR balance by utilizing additional visual cues. To examine how different visual approaches (static, rhythmic, spatial, and center of pressure (CoP) based feedback) affect balance in VR, we recruited 100 people (50 with balance impairments due to multiple sclerosis and 50 without balance impairments) across two different geographic locations (United States and Bangladesh). All people completed both standing visual exploration as well as standing reach and grasp tasks. Results demonstrated that static, rhythmic, and CoP visual feedback approaches enhanced balance significantly ( ) in VR for people with balance impairments. The methods described in this study could be applied to design more accessible virtual environments for people with balance impairments.

Sit-to-walk strategy classification in healthy adults using hip and knee joint angles at gait initiation

Forward continuation, balance, and sit-to-stand-and-walk (STSW) are three common movement strategies during sit-to-walk (STW) executions. Literature identifies these strategies through biomechanical parameters using gold standard laboratory equipment, which is expensive, bulky, and requires significant post-processing. STW strategy becomes apparent at gait-initiation (GI) and the hip/knee are primary contributors in STW, therefore, this study proposes to use the hip/knee joint angles at GI as an alternate method of strategy classification. To achieve this, K-means clustering was implemented using three clusters corresponding to the three STW strategies; and two feature sets corresponding to the hip/knee angles (derived from motion capture data); from an open access online database (age: 21-80 years; n = 10). The results identified forward continuation with the lowest hip/knee extension, followed by balance and then STSW, at GI. Using this classification, strategy biomechanics were investigated by deriving the established biomechanical quantities from literature. The biomechanical parameters that significantly varied between strategies (P < 0.05) were time, horizontal centre of mass (COM) momentum, braking impulse, centre of pressure (COP) range and velocities, COP-COM separation, hip/knee torque and movement fluency. This alternate method of strategy classification forms a generalized framework for describing STW executions and is consistent with literature, thus validating the joint angle classification method.

The impact of anthropometric measures on plantar pressure distribution in male handball players and non-athletes: A cross-sectional study

BACKGROUND

Increasing body anthropometry brings substantial spinal stress, which influences the spinal curvatures; this in turn may affect the foot plantar pressure distribution.

OBJECTIVES

This study investigated the impact of body anthropometry on static plantar pressure distribution and their relationship among handball players and non-athletes subjects.

METHODS

Thirty handball players aged from 21 to 26 years, and thirty age-matched non-athletes subjects aged from 21 to 28 years participated in this study. The spinal lordosis and kyphosis angles, trunk length, pelvic tilting, and pelvic rotation were evaluated using Formetric 4-dimensions and the Pedoscan device was used to assess the plantar pressure distribution.

RESULTS

The handball players were significantly taller, heavier, and have a long trunk length than non-athletes group (p < 0.05), and a significantly increased thoracic kyphosis, forefeet pressure distribution compared to non-athletes group (p < 0.05). The handball players had a significantly increased forefeet pressure distribution compared to the rearfeet pressure distribution (p < 0.05), a high positive correlation between body height, and both trunk length and kyphosis angle (r = 0.932, 0.665 respectively), and the body height showed a high positive correlation with the forefeet pressure distribution (r = 0.665). There was a high positive correlation between the handball players' thoracic kyphosis and forefeet pressure distribution (r = 0.751).

CONCLUSION

Increasing the handball players' body height was related to increased thoracic kyphosis and forefeet pressure distribution compared to non-athletes subjects. Additionally, the kyphotic posture of handball players is associated with increasing the total forefeet pressure distribution compared to the total rearfeet pressure distribution.

The Effects of Ankle Taping on Measures of Ground Reaction Forces and Jump Height During a Sport-Specific Vertical Jump in Youth Basketball Players

The purpose of this study was to investigate the effects of ankle taping using zinc oxide tape versus no tape to measure ground reaction forces (GRF) and vertical jump height during a sport-specific vertical jump test in youth basketball players. Participants were recruited through purposive sampling and completed a basketball specific vertical jump test with and without zinc oxide tape. Mean sway velocity, 95% ellipse area, and path length were measured using the AMTI© force platform and vertical jump height using a Vertec© device. A paired t-test with a significance level of p < .05 was used for analysis. 23 individuals participated (11 females, 12 males; aged M = 15.22 years; height M = 171.43 cm; mass M = 64.72 kg). There was a statistically significant decrease in jump height with tape (M = 57.33 cm) compared to without tape (M = 58.84 cm), 95% CI [2.74, 0.28], t (20) = -2.56, p < .05, d = .56; statistically significant decrease in 95% ellipse area with tape (M = 2.64 cm.cm) compared to without tape (M = 3.30 cm.cm), 95% CI [0.50, 0.02], t (22) = -2.26, p < .05, d = .47; statistically significant decrease in sway velocity with tape (M = 2.82 m/sec) compared to without tape (M = 4.08 m/sec), 95% CI [7.47, 0.27], t (22) = -2.22, p < .05, d = .46; and a statistically significant decrease in path length with tape (M = 120.93 cm) compared to without tape (M = 170.10 cm), 95% CI [37.37, 1.33], t (22) = -2.23, p < .05, d = .46, with a medium effect size for all variables. The application of taping the ankles resulted in increased ankle stability at landing, however, basketball jumping performance may be negatively affected as taping resulted in a decreased vertical jump height.

Impaired postural control in diabetes-a predictor of falls?

New evidence points toward that impaired postural control judged by center of pressure measures during quiet stance is a predictor of falls in people with type 1 and type 2 diabetes-even in occurrence of well-known risk factors for falls.

INTRODUCTION/AIM

People with type 1 diabetes (T1D) and type 2 diabetes (T2D) are at risk of falling, but the association with impaired postural control is unclear. Therefore, the aim was to investigate postural control by measuring the center of pressure (CoP) during quiet standing and to estimate the prevalence ratio (PR) of falls and the fear of falling among people with diabetes compared to controls.

METHODS

In a cross-sectional study, participants with T1D (n = 111) and T2D (n = 106) and controls without diabetes (n = 328) were included. Study procedures consisted of handgrip strength (HGS), vibration perception threshold (VPT), orthostatism, visual acuity, and postural control during quiet stance measured by CoPArea (degree of body sway) and CoPVelocity (speed of the body sway) with "eyes open," "eyes closed" in combination with executive function tasks. A history of previous falls and fear of falling was collected by a questionnaire. CoPArea and CoPVelocity measurements were analyzed by using a multiple linear regression model. The PR of falls and the fear of falling were estimated by a Poisson regression model. Age, sex, BMI, previous falls, alcohol use, drug, HGS, VPT, orthostatism, episodes of hypoglycemia, and visual acuity were covariates in multiple adjusted analyses.

RESULTS

Significantly larger mean CoPArea measures were observed for participants with T1D (p = 0.022) and T2D (0.002), whereas mean CoPVelocity measures were only increased in participants with T2D (p = 0.027) vs. controls. Additionally, T1D and T2D participants had higher PRs for falls (p = 0.044, p = 0.014) and fear of falling (p = 0.006, p < 0.001) in the crude analyses, but the PRs reduced significantly when adjusted for mean CoPArea and mean CoPVelocity, respectively. Furthermore, multiple adjusted PRs were significantly higher than crude the analyses.    CONCLUSION: Impaired postural control during quiet stance was seen in T1D and T2D compared with controls even in the occurrence of well-known risk factors. and correlated well with a higher prevalence of falls.

Differences in Body Balance According to Body Mass Classification among Brazilian Jiu-Jitsu Athletes

Background: Body weight is an important aspect in the development of components of physical fitness that can affect athletic performance. The purpose of this study was to examine the differences in body balance of Brazilian Jiu-Jitsu (BJJ) athletes according to body mass classification: underweight/normal weight (UW/NW); overweight/obese (OW/OB). Material and Methods: The study was conducted among 69 BJJ athletes (age 23.26 ± 3.53) and 93 non-practicing adults (age 21.73 ± 2.32). This study was based on a quantitative assessment of body balance on the Zebris PDM platform during two tests, i.e., with eyes open and closed. Results: The total path of the center of pressure (COP TTL) was significantly higher in participants with UW/NW compared to those with OW/OB, both in participants from the study group and control group (p < 0.001). COP TTL was significantly lower in UW/NW BJJ athletes than in participants in the control group with the same BMI category (987.4 mm vs. 1238.5 mm and 1080.59 mm vs. 1280.70 mm, respectively) (p < 0.001). Conclusions. BJJ training is associated with a better balance in terms of COP TTL in the case of people with normal or underweight. The presence of excess body weight has a positive effect on lower COP TTL values in both practicing and non-practicing people.

Combined balance and plyometric training enhances knee function, but not proprioception of elite male badminton players: A pilot randomized controlled study

Objectives

To investigate the effect of combined balance and plyometric training on knee function and proprioception of elite badminton athletes.

Methods

Sixteen elite male badminton players (age: 20.5 ± 1.1 years, height: 177.8 ± 5.1 cm, weight: 68.1 ± 7.2 kg, and training experience: 11.4 ± 1.4 years) volunteered to participate and were randomly assigned to a combined balance and plyometric training (CT) (n = 8) and plyometric (PT) group (n = 8). The CT group performed balance combined with plyometric training three times a week over 6 weeks (40 min of plyometrics and 20 min of balance training); while the PT group undertook only plyometric training for the same period (3-4 sets × 8-12 reps for each exercise). Both groups had the same technical training of badminton.

Results

The knee function and proprioception were assessed at baseline and after the intervention by measuring the performance of single-legged hop tests (LSIO, LSIT, LSIC, LSIS), standing postural sway (COPAP, COPML), and LSI of dominant leg and non-dominant leg. The results showed that as compared to PT, CT induced significantly greater improvements in LSIT and LSIS (p < 0.001) and significant greater percent increase in NAP (p = 0.011). The changes in LSIO, LSIC, DAP, NAP, LSIAP, DML, NML, and LSIML induced by CT did not differ from that induced by PT (p > 0.213).

Conclusion

In elite badminton players, intervention using CT holds great promise to augment the benefits for knee function compared to the intervention using PT only, and at the same time, with at least comparable benefits for proprioception. Future studies are needed to examine and confirm the results of this study.

Evaluation of the Foot Center of Pressure Estimation from Pressure Insoles during Sidestep Cuts, Runs and Walks

Estimating the foot center of pressure (CoP) position by pressure insoles appears to be an interesting technical solution to perform motion analysis beyond the force platforms surface area. The aim of this study was to estimate the CoP position from Moticon® pressure insoles during sidestep cuts, runs and walks. The CoP positions assessed from force platform data and from pressure insole data were compared. One calibration trial performed on the force platforms was used to localize the insoles in the reference coordinate system. The most accurate results were obtained when the motion performed during the calibration trial was similar to the motion under study. In such a case, mean accuracy of CoP position have been evaluated to 15±4mm along anteroposterior (AP) axis and 8.5±3mm along mediolateral (ML) axis for sidestep cuts, 18±5mm along AP axis and 7.3±4mm along ML axis for runs, 15±6mm along AP axis and 6.6±3mm along ML axis for walks. The accuracy of the CoP position assesment from pressure insole data increased with the vertical force applied to the pressure insole and with the number of pressure cells involved.

Postural balance in frequent lucid dreamers: a replication attempt

Study Objectives

Early research suggests that the vestibular system is implicated in lucid dreaming, e.g. frequent lucid dreamers outperform others on static balance tasks. Furthermore, gravity-themed dreams, such as flying dreams, frequently accompany lucid dreaming. Nonetheless, studies are scarce.

Methods

We attempted to: (1) replicate previous findings using more sensitive static balance measures and (2) extend these findings by examining relationships with dreamed gravity imagery more generally. 131 participants (80 F; Mage=24.1 ± 4.1 yrs) estimated lucid dreaming frequency then completed a 5-day home log with ratings for dream lucidity awareness, control, and gravity sensations (flying, falling). They then performed balance tasks on a sensitive force plate, i.e. standing on one or both feet, with eyes open or closed. Center of pressure (CoP) Displacement and CoP Velocity on each trial measured postural stability.

Results

Findings partially support the claim of a vestibular contribution to lucid dreaming. Frequent lucid dreamers displayed better balance (lower CoP Velocity) than did other participants on some trials and lucid dreaming frequency was globally correlated with better balance (lower CoP Velocity). Lower CoP Velocity was related to flying sensations in men’s dreams and with more dream control in women’s dreams. However, body height—possibly due to its relationship to sex—and levels of sleepiness confound some of these effects.

Conclusion

While findings only provide a partial replication of previous work, they nonetheless support an emerging view that the vestibular system underlies basic attributes of bodily self-consciousness, such as feelings of self-agency and self-location, whether such consciousness occurs during wakefulness or dreaming.

Effects of subthreshold electrical stimulation with white noise, pink noise, and chaotic signals on postural control during quiet standing

BACKGROUND

The stochastic resonance (SR) phenomenon has been used to improve postural control through the application of imperceptible noise to the somatosensory system. White noise signals have been applied in numerous SR studies on postural control. However, because the SR effect depends on the noise structure, the stimulation effects of signals with different structures, such as pink noise and chaotic signals, on postural control, must be determined to achieve better clinical applications of SR technology.

RESEARCH QUESTION

During quiet standing, how is postural control affected by subthreshold electrical stimulation to the knee joints when signals with different structures (white noise, pink noise, and chaotic signals) are used?

METHODS

Sixteen healthy young adults stood quietly for 40 s with their eyes closed. To evaluate postural sway, we calculated the mean velocity, root mean square (CoP_RMS), and range (CoP_Range) values for the center of pressure (CoP) in the anteroposterior direction. The standing task was conducted under subthreshold electrical stimulation with white noise, pink noise, and chaotic signals based on the Lorenz system, in addition to the no-stimulation condition. The four stimulation conditions were randomized within each set and repeated seven times.

RESULTS

Significant effects of stimulation were observed in the CoP_RMS and CoP_Range values. The CoP_RMS value under the pink noise signal was significantly lower than that under the no-stimulation condition. The CoP_Range value also tended to decrease under the pink noise signal compared with the no-stimulation condition; however, the differences were not statistically significant. No significant changes were found with the white noise and chaotic signals compared with the no-stimulation condition.

SIGNIFICANCE

We demonstrated that the pink noise signal was more effective in reducing postural sway than the white noise and chaotic signals based on the Lorenz system during quiet standing.

Postural Balance in Relation with Vision and Physical Activity in Healthy Young Adults

Postural balance is an essential part of a wide range of activities, from daily living tasks to sports. Regularly repeated physical and/or sport activities improve both the postural performance and the postural strategy. The aim of our study was to evaluate if the physical activity level is a factor that influences postural balance performance, including the impact of vision and gender, in healthy young adults. Postural balance was assessed in 78 subjects (38 males and 40 females, aged 20.64 ± 1.18 years) by using the PoData system, in open (EO) and closed (EC) eye conditions. Based on the physical activity level, subjects were classified in two groups—low physical activity level (n = 36, 46.15%) and moderate physical activity level (n = 42, 53.85%). A group significant difference was found only for the average centre of pressure (CoP) deviations on the latero-lateral axis (CoP_X), with a higher lateral deviation of the CoP (toward right) in the low physical activity group (F = 4.005, p = 0.04). CoP path length, the 90% confidence ellipse and maximum CoP speed were significantly increased in EC conditions. A statistically significant interaction effect (vision × physical activity) was observed for the CoP path length (F = 7.9, p = 0.006).

Influence of invertor and evertor muscle fatigue on functional jump tests and postural control: A prospective cross-sectional study

OBJECTIVE

Fatigue of the ankle's stabilizing muscles may influence the performance of functional activities and postural control. The purpose of this study was to evaluate the performance of healthy young adults using functional jump tests and static posturography control under pre- and post-fatigue conditions of the ankle invertor and evertor muscles.

METHODS

Thirty physically active healthy male and female (15 male and 15 female) volunteers (24.3 years) were enrolled in this prospective cross-sectional study. Participants performed tests on one day under a non-fatigued state of invertor and evertor muscles and on the second day in a fatigued state. Tests included static posturography on a force platform in a bipedal stance with eyes open and closed and in one-legged support with eyes open and functional jump tests (figure-of-8, side hop, 6-m crossover hop, and square hop). Fatigue of the ankle invertor and evertor muscles was induced using isokinetic dynamometry with 30 repetitions at 120°/s.

RESULTS

Participants had an average age of 24.3 years (SD ± 2.08), the height of 1.73 m (SD ± 0.08), and a weight of 68.63 kg (SD ± 10.29). The average Body Mass Index (BMI) was 22.88 (SD ± 2.46). A decrease in performance was observed in functional activities and postural control under all conditions after the induction of muscle fatigue, except for the speed at a bipedal stance with eyes open.

CONCLUSIONS

Functional jump tests are low cost and useful for clinical practice and evaluation of the effects of muscle fatigue and could be used in clinical practice.

Efficacy of prosthetic rehabilitation in rotationplasty following Ewing's sarcoma: A case study

PURPOSE

Restoration of functional mobility including gait and balance are fundamental to prosthetic rehabilitation in children with rotationplasty. The literature to characterize and investigate the correlation between postural balance and gait following rotationplasty are scarce. This study examines the characteristics of balance and prosthetic gait in a subject with rotationplasty and checks whether any association exists between them.

METHODS

A 14-year-old boy with rotationplasty following Ewing's sarcoma was fitted with a custom made prosthesis. Center of pressure (COP) measures using the HUMAC® Balance & Tilt System (CSMi, Stoughton, MA), temporal-spatial gait parameters, and energy expenditure measured by a 10 meter walk test were recorded using the new and old prosthesis. A control subject was used for comparison.

RESULTS

The stability score, path length, and average velocity of COP improved in a new prosthesis for both standing conditions. Gait parameters were improved and energy expenditure was marginally reduced with the new prosthesis. However, overall prosthetic gait was significantly different compared to the control subject.

CONCLUSION

This subject-centric approach successfully improved balance, gait parameters, and energy expenditure by providing better alignment, fit, and comfort with a custom prosthesis.

Test-Retest Reliability of Low-Cost Posturography for Assessing Postural Stability Control Performance during Standing

Postural stability control performance assessment is necessary in providing important information for individuals who are at risk of falling or who have balance impairment. Instrumented assessment is suggested as a valid and reliable test, but the cost and the difficulty of setup are significant limitations. The aim of this cross-sectional (test-retest reliability) study was to develop and determine the reliability of a low-cost posturography for assessing postural stability control performance during standing. The low-cost posturography was developed with four load cells and an acrylic platform. The center of pressure (COP) displacement and velocity were analyzed using written software. Test-retest reliability was performed with six different standing postural stability tests in twenty healthy volunteers on two different days. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), coefficient of variation (CV), and Bland-Altman plot and limits of agreements (LOA) were used for analyses. The low-cost posturography was accurate (ICC = 0.99, p < 0.001; SEM = 0.003 cm) when compared to the true with calculated X and Y coordinates, with a moderate to excellent test-retest reliability for both COP displacement (ICCs ranged 0.62-0.91, p < 0.05; SEMs ranged 17.92-25.77%) and COP velocity (ICCs ranged 0.62-0.91, p < 0.05; SEMs ranged 18.09-27.69%) in all standing postural stability tests. Bland-Altman plots and LOAs suggested good agreement of tested parameters from the developed low-cost posturography between different days. In conclusion, the developed low-cost posturography had adequate reliability for assessing COP displacement and velocity during standing postural control stability performance tests.

Introducing an Activity-Based Balance Index for Soccer Players: A Validity and Reliability Study

Objectives: The aim of this study was to evaluate the validity and reliability of introducing a new activity-based balance index using a triaxial accelerometer during activity. Methods: Twenty seven soccer players (age: 14.5 ± 0.4 years old, body mass: 58.3 ± 9.3 kg, height: 172 ± 8 cm) who participated in the national premier league were recruited. The participants were tested for their balance, activity, and skill in four tests: (I) one leg stance; (II) dynamic Y balance; (III) running; and (IV) dribbling slalom. The acceleration of the body was recorded using an accelerometer during those tests. By processing acceleration data, a new activity-based balance index (ABI) was calculated based on the velocity, acceleration, and position index of soccer players. Using intra-class correlation coefficients (ICC), reliability was calculated. Results: Reliability was high (ICC = 0.87 - 0.89; 95% CI = 0.77 - 0.93) in calculating ABI for the three activities performed in the tests. A significant positive correlation between ABI and both static and dynamic balance scores (r = 0.62, P = 0.002) was observed. Furthermore, negative correlation was found significantly between ABI and dribbling scores (r = -0.61, P = 0.026) and Y Balance test (r = 0.6, P = 0.002). Conclusions: In conclusion, the introduced ABI demonstrates great potential to determine balance and skill scores based on accelerometer-based measures.

Comparison of Postural Sway, Plantar Cutaneous Sensation According to Saccadic Eye Movement Frequency in Young Adults

The crossover trial study aimed to identify the saccadic eye movement (SEM) frequency to improve postural sway (PS) and plantar cutaneous sensation (PUS) in young adults. The 17 participants randomly performed 0.5-, 2-, and 3-Hz SEM. The SEM frequency was determined to allow the target to appear once per 2 s (0.5 Hz), twice per second (2 Hz), or thrice per second (3 Hz). SEM performance time was 3 min with a washout period of 5 min. PS and PUS were measured at baseline and during 0.5-Hz, 2-Hz, and 3-Hz SEMs using a Zebris FDM 1.5 force plate. PS was determined by measuring the sway area, path length, and speed of center of pressure (COP) displacement, and PUS was determined via the plantar surface area (PSA). In PS parameters, there was a significant difference among the SEM frequencies in the COP_{sway area} PSA_{left foot} and PSA_{right foot}. Compared to that at baseline, COP_{sway area} decreased at 0.5 Hz and 2 Hz, while PSA_{left foot} and PSA_{right foot} increased at 2 Hz. These results suggest that 2 Hz SEM may improve PS and PSA.

Using robotic mechanical perturbations for enhanced balance assessment

Balance impairment is critical for many patient groups such as those with neural and musculoskeletal disorders and also the elderly. Accurate and objective assessment of balance performance has led to the development of several indices based on the measurement of the center of pressure. In this study, a robotic device was designed and fabricated to provide controlled and repeatable mechanical perturbations to the standing platform of the user. The device uses servo-controlled actuators and two parallel mechanisms to provide independent rotations in mediolateral and anterior-posterior directions. The device also provides visual feedback of the center of pressure position to the user. Functional tests were run and showed that the device is able to provide an appropriate dynamics (time constant of 0.19 s and bandwidth of 0.85 Hz) for the two motions. The efficacy of the device on the balance assessment was then evaluated experimentally. Ten healthy subjects performed a balance task with and without perturbations and seven center of pressure indices were measured. It was shown that the sensitivity of the indices to the user's performance was statistically increased in all indices particularly in anterior/posterior direction when the mechanical perturbations were present.

Effect of Visual Condition on Performance of Balance-Related Tasks in Elite Dance Students

The purpose of this study was to investigate the effects of visual condition (low light, full light, and full light with mirror) on balance control and technical form during two technical dance movements in a group of elite collegiate dance students. Dancers demonstrated higher center of pressure velocity indicating lower control while performing a static dance task (parallel relevé retiré) and a dynamic dance task (fondu relevé en croix) under low light conditions than either lighted condition. Measures of Western ballet technique (pelvic obliquity, knee extension, and ankle plantar flexion) showed no decrement under low light conditions. No effect of concurrent mirror feedback was found on either center of pressure velocity or technical requirements of the dance tasks.

Long-term impact of mild traumatic brain injury on postural stability and executive function

OBJECTIVE

A substantial number of individuals present with prolonged symptoms after a mild traumatic brain injury (mTBI) or concussion. This has warranted the development of assessment tools that can reliably detect prolonged symptoms after an mTBI. At present, a gold standard diagnostic tool for accurately identifying such prolonged symptoms is not available. The purpose of this study is to utilize specific measures of standing balance, cognitive function, and bimanual coordination to examine persisting long-term deficits in individuals with mTBI.

METHODS

A total of 18 (medically diagnosed with an mTBI within the last year) and 14 (healthy age-matched controls) individuals participated in the study. Assessment tools included NIH Toolbox Cognition Battery (NIHTB-CB), TEMPA, and Purdue pegboard (bimanual coordination) and standing balance on a force platform.

RESULTS

Individuals with mTBI demonstrated lower scores in all measures of cognition with statistically significant difference (p = 0.03) in executive function. The clinical tests of bimanual coordination did not show any statistically significant differences between groups. Postural stability was significantly reduced (p = 0.039) in the mTBI group.

CONCLUSION

Our results show long-term performance deficits (cognition and postural stability) that persist in individuals with mTBI. In addition, to the best of our knowledge, this is the first study to identify cognitive deficits in individuals with mTBI by utilizing NIHTB-CB. Knowledge gained from this study might affect decisions of return-to-play or return-to-learn in individuals with a history of mTBI(s).

Whole-Body Dynamic Analysis of Challenging Slackline Jumping

Maintaining balance on a slackline is a challenging task in itself. Walking on a high line, jumping and performing twists or somersaults seems nearly impossible. Contact forces are essential to understanding how humans maintain balance in such challenging situations, but they cannot always be measured directly. Therefore, we propose a contact model for slackline balancing that includes the interaction forces and torques as well as the position of the Center of Pressure. We apply this model within an optimization framework to perform a fully dynamic motion reconstruction of a jump with a rotation of approximately 180 ° . Newton’s equations of motions are implemented as constraints to the optimization, hence the optimized motion is physically feasible. We show that a conventional kinematic analysis results in dynamic inconsistencies. The advantage of our method becomes apparent during the flight phase of the motion and when comparing the center of mass and angular momentum dynamics. With our motion reconstruction method all momentum is conserved, whereas the conventional analysis shows momentum changes of up to 30%. Furthermore, we get additional and reliable information on the interaction forces and the joint torque that allow us to further analyze slackline balancing strategies.

Preseason to Postseason Changes on the BTrackS Force Plate in a Sample of College Athletes

CONTEXT

Balance testing is a vital component in the evaluation and management of sport-related concussion. Few studies have examined the use of objective, low-cost, force-plate balance systems and changes in balance after a competitive season.

OBJECTIVE

To examine the extent of preseason versus postseason static balance changes using the Balance Tracking System (BTrackS) force plate in college athletes.

DESIGN

Pretest, posttest design.

SETTING

Athletic training facility.

PARTICIPANTS

A total of 47 healthy, Division-I student-athletes (33 males and 14 females; age 18.4 [0.5] y, height 71.8 [10.8] cm, weight 85.6 [21.7] kg) participated in this study.

MAIN OUTCOME MEASURES

Total center of pressure path length was measured preseason and postseason using the BTrackS force plate. A Wilcoxon signed-rank test was conducted to examine preseason and postseason changes. SEM and minimal detectable change were also calculated.

RESULTS

There was a significant difference in center of pressure path length differed between preseason (24.6 [6.8] cm) and postseason (22.7 [5.4] cm) intervals (P = .03), with an SEM of 3.8 cm and minimal detectable change of 10.5 cm.

CONCLUSIONS

Significant improvements occurred for center of pressure path length after a competitive season, when assessed using the BTrackS in a sample of college athletes. Further research is warranted to determine the effectiveness of the BTrackS as a reliable, low-cost alternative to force-plate balance systems. In addition, clinicians may need to update baseline balance assessments more frequently to account for improvements.

Correlation Between Mechanography and Clinical Parameters at Six Months After Hip Fracture Surgery

OBJECTIVE

To investigate the correlation between mechanography and clinical parameters in older people at 3 and 6 months after hip fracture surgery.

METHODS

A longitudinal follow-up study was conducted in university hospitals with 38 patients at 3 months and 29 patients at 6 months after hip fracture surgery. Subjects 65 years and older completed measurements on the Berg Balance Scale (BBS), Functional Ambulation Category (FAC), walking ability by Koval, Korean version of the fatigue, resistance, ambulation, illnesses, and loss of weight (K-FRAIL) scale, and hand grip strength. The Romberg test with center of foot pressure (COP), chair rise test (CRT), and maximal power (W/kg) were conducted using the Leonardo Mechanograph.

RESULTS

COP area and pathway length were correlated with BBS at 3 and 6 months. Change in BBS was correlated with change in COP area, but not with change in COP length. COP area and pathway length were correlated with K-FRAIL at 3 months after hip fracture surgery. The same COP variables showed correlations with FAC and walking ability by Koval at 6 months after surgery. Maximal power during CRT had correlation with chair rise time but not with other clinical parameters.

CONCLUSION

The study revealed correlations between mechanography and clinical parameters in older people at 3 and 6 months after hip fracture surgery. Both the clinical assessment and objective test with mechanography may be required for the quantitative and sensitive measurement of postural balance and lower limb muscle power.

Toward more reliable stability measurements in stance: recommendations for number of measurements, foot position and feedback -- a cross-sectional study among servicemen

BACKGROUND

In the military, insufficient postural stability is a risk factor for developing lower extremity injuries. Postural stability training programs are effective in preventing these injuries. However, an objective method for the measurement of postural stability in servicemen is lacking. The primary objective of this study was to assess the influence of the number of repetitions, different foot positions and real-time visual feedback on postural stability, as well as their effects on the intrasession reliability of postural stability measurements in servicemen. The secondary objective was to assess the concurrent validity of the measurements.

METHODS

Twenty healthy servicemen between 20 and 50 years of age and in active duty were eligible for this quantitative, cross-sectional study. The measurements took place on a force plate, measuring the mean velocity of the center of pressure. The participants were asked to stand as still as possible in three different foot positions (wide stance, small stance, and on one leg), five times each for 45 s each time, and the measurements were performed with and without real-time visual feedback.

RESULTS

We observed a significant main effect of foot position (P < 0.001), but not of visual feedback (P = 0.119) or repetition number (P = 0.915). Postural stability decreased in the more challenging foot positions. The ICC estimates varied from 0.809 (one repetition in wide stance) to 0.985 (five repetitions on one leg). The common variance (R²) between different foot positions without feedback varied between 0.008 (wide stance) and 0.412.

CONCLUSIONS

To yield reliable data, wide-stance measurements should be conducted three times, and small-stance measurements and measurements on one leg should be conducted two times. The scores of a measurement in a particular foot position cannot predict the scores of measurements in other foot positions.

Trunk postural control during unstable sitting differs between patients with patellofemoral pain syndrome and healthy people: A cross-sectional study

BACKGROUND

Patellofemoral pain syndrome (PFPS) is a common orthopedic problem with a high prevalence among young women. Patients with PFPS have altered trunk muscle activity, impaired postural control and greater displacement of the center of pressure (COP) while standing. Training in unstable sitting, by putting more emphasis on trunk sensory receptors, may improve trunk proprioception by minimizing the role of the lower extremities. The aim of this study was to compare trunk postural control in healthy persons and in patients with PFPS.

METHODS

Twenty-one women diagnosed with PFPS and 21 healthy women volunteered to participate in this cross-sectional study. The participants were asked to maintain trunk postural balance on an unstable sitting device, and COP indices of trunk postural control were compared between groups.

RESULTS

All COP indices (e.g., mean anterior-posterior and lateral COP displacement, mean COP velocity and mean area of COP displacement) were significantly increased in participants with PFPS in comparison to healthy controls (P < 0.001). The effect sizes of all the indices were greater than 0.80.

CONCLUSIONS

Trunk postural control is impaired in patients with PFPS, and this finding has clinical implications for rehabilitation in patients with PFPS. Adding seated postural control training to conventional physical therapy management in patients with PFPS may have beneficial effects by emphasizing trunk proprioception while minimizing the role of the lower extremities.