Biomechanical assessment of dynamic balance: Specificity of different balance tests

Short-term effects of kinesiology taping on static and dynamic balance in healthy subjects

Background

As a therapeutic tool, kinesiology taping (KT) has become increasingly popular for musculoskeletal injuries utilized by physiotherapists. KT has been found to have effects on facilitating muscle strength by generating a concentric pull on the fascia. However, little is known about KT in the improvement of dynamic and static balance. This study aims to explore whether KT on the quadriceps muscle has any immediate effects on static and dynamic balance.

Methodology

Twenty-seven healthy individuals (13 males and 14 females, aged 22 to 29) were recruited in a crossover study with two conditions: KT and no taping. KT was applied to the quadriceps muscle for the taping group, with the control receiving no taping. Pre- and post-test measurements were taken to give an indication of the effect of the tape on balance performance. Center of Pressure Excursion (COPE) and Time to Stabilization (TTS) when landing from a hop test and Y Balance test combined score (YBTCS) were used to assess a stabilizing balance activity and a dynamic balance. The pre- and post-intervention were collected, with differences explored using repeated measures ANOVA with time and condition (tape) factor analysis.

Results

We found a significant improvement (p ≤ 0.05) with a moderate to large effect size in YBTCS between KT and no taping, indicating enhanced balance performance in the KT group. However, no significant difference (p ≥ 0.05) with small to moderate effect size was found in COPE or TTS between the two conditions during landing tests, suggesting similar balance capabilities in these specific measures.

Conclusion

The use of KT shows no significant immediate effect on static balance in healthy individuals when applied to the quadriceps muscles; however, it demonstrates a positive immediate effect on dynamic balance.

Influence of oral motor tasks on postural muscle activity during dynamic reactive balance

BACKGROUND

Jaw clenching improves dynamic reactive balance on an oscillating platform during forward acceleration and is associated with decreased mean sway speed of different body regions.

OBJECTIVE

It is suggested that jaw clenching as a concurrent muscle activity facilitates human motor excitability, increasing the neural drive to distal muscles. The underlying mechanism behind this phenomenon was studied based on leg and trunk muscle activity (iEMG) and co-contraction ratio (CCR).

METHODS

Forty-eight physically active and healthy adults were assigned to three groups, performing three oral motor tasks (jaw clenching, tongue pressing against the palate or habitual lower jaw position) during a dynamic one-legged stance reactive balance task on an oscillating platform. The iEMG and CCR of posture-relevant muscles and muscle pairs were analysed during platform forward acceleration.

RESULTS

Tongue pressing caused an adjustment of co-contraction patterns of distal muscle groups based on changes in biomechanical coupling between the head and trunk during static balancing at the beginning of the experiment. Neither iEMG nor CCR measurement helped detect a general neuromuscular effect of jaw clenching on the dynamic reactive balance.

CONCLUSION

The findings might indicate the existence of robust fixed patterns of rapid postural responses during the important initial phases of balance recovery.

Effect of Verbal Encouragement on Postural Balance in Individuals with Intellectual Disabilities

This study investigated the effect of verbal encouragement (VE) on static and dynamic balance in individuals with intellectual disabilities (IDs). A total of 13 mild IDs and 12 moderate IDs participants underwent static balance tests (bipedal stance on firm surface, under open eyes (OEs) and closed eyes (CEs), and foam surface, unipedal stance on firm surface) and dynamic balance assessments (Y Balance Test (YBT) and Expanded Timed Up-and-Go Test (ETUGT)) under VE and no VE (NO/VE) conditions. VE significantly reduced center of pressure mean velocity (CoPVm) values for mild IDs in firm bipedal CEs conditions. The mild IDs group exhibited improved YBT scores and enhanced ETUGT performances for both groups under VE. Incorporating VE as a motivational strategy in balance training interventions can positively impact static and dynamic balance in individuals with mild IDs, especially in challenging conditions like unipedal stances on firm surfaces.

Direct Current Stimulation over the Primary Motor Cortex, Cerebellum, and Spinal Cord to Modulate Balance Performance: A Randomized Placebo-Controlled Trial

OBJECTIVES

Existing applications of non-invasive brain stimulation in the modulation of balance ability are focused on the primary motor cortex (M1). It is conceivable that other brain and spinal cord areas may be comparable or more promising targets in this regard. This study compares transcranial direct current stimulation (tDCS) over (i) the M1, (ii) the cerebellum, and (iii) trans-spinal direct current stimulation (tsDCS) in the modulation of balance ability.

METHODS

Forty-two sports students were randomized in this placebo-controlled study. Twenty minutes of anodal 1.5 mA t/tsDCS over (i) the M1, (ii) the cerebellum, and (iii) the spinal cord, as well as (iv) sham tDCS were applied to each subject. The Y Balance Test, Single Leg Landing Test, and Single Leg Squat Test were performed prior to and after each intervention.

RESULTS

The Y Balance Test showed significant improvement after real stimulation of each region compared to sham stimulation. While tsDCS supported the balance ability of both legs, M1 and cerebellar tDCS supported right leg stand only. No significant differences were found in the Single Leg Landing Test and the Single Leg Squat Test.

CONCLUSIONS

Our data encourage the application of DCS over the cerebellum and spinal cord (in addition to the M1 region) in supporting balance control. Future research should investigate and compare the effects of different stimulation protocols (anodal or cathodal direct current stimulation (DCS), alternating current stimulation (ACS), high-definition DCS/ACS, closed-loop ACS) over these regions in healthy people and examine the potential of these approaches in the neurorehabilitation.

Validity and Reliability of Dynamic and Functional Balance Tests in People Aged 19-54: A Systematic Review

Evaluating an impairment in an individual's capacity to maintain, achieve, or restore balance suggests a deficiency in postural control. For effective identification of individuals at risk for falls, balance assessment should exhibit reliability, validity, and ease of use. This systematic review concentrated on dynamic and functional balance assessment methods and their validity in healthy adults aged 19-54. The objective was to clarify the tools that health professionals can utilize to assess balance in this healthy population.

Methods

A systematic literature search conducted in August 2019 yielded nine articles meeting predefined selection criteria. Inclusion criteria required studies featuring healthy adult participants aged 19-54, published in English, and focusing on dynamic and functional balance testing. Exclusion criteria excluded studies involving participants with chronic diseases or musculoskeletal disorders, systematic reviews, professional athletes, and those lacking specific participant age information. The quality of the studies was evaluated using a modified PEDro scale.

Results

This review analyzed ten distinct postural balance tests. The Star Excursion Balance Test and Y-Balance Test exhibited moderate to high reliability, establishing them as dependable measures of dynamic balance. The Nintendo Wii Balance Board, Clever Balance Board, and Posturomed device also displayed excellent reliability for assessing dynamic postural balance. Comparing one-arm and two-arm functional reach tests, the one-arm reach test emerged as a more suitable option for evaluating dynamic balance among young adults. Moreover, an investigation comparing three dynamic balance tests (one-leg jump landing, Posturomed device, and stimulated forward fall) revealed a low correlation among these tests, indicating a measurement of different balance constructs.

Discussion

In conclusion, the Y-Balance Test stands out as the most practical dynamic balance assessment for clinical use, characterized by a standardized protocol, good repeatability, affordability, and ease of application. The Nintendo Wii Balance Board also presents itself as a cost-effective and reliable tool for dynamic balance evaluation in clinical settings. It is crucial to recognize that these tests appraise discrete postural skills, preventing direct comparisons between test outcomes. This review equips healthcare professionals with valuable insights into optimal balance assessment methods for the healthy, 19 to 54 aged population.

Levels of evidence

Level 3.

Falls perceived as significant by lower limb prosthesis users are generally associated with fall consequences rather than circumstances

PURPOSE

To determine if falls perceived as significant by lower limb prosthesis (LLP) users were associated with fall circumstances and/or consequences.

MATERIALS AND METHODS

The circumstances and consequences of LLP users' most significant fall in the past 12-months were collected using the Lower Limb Prosthesis User Fall Event Survey. Participants rated fall significance from 0 (not significant) to 10 (extremely significant), which was then dichotomized into "low" and "high". Binary logistic regression was used to assess associations between fall significance and fall circumstances and consequences.

RESULTS

Ninety-eight participants were included in the analysis. Five fall consequences were associated with greater significance: major injury (OR = 26.7, 95% CI: 1.6-459.6, p = 0.024), need to seek medical treatment (OR = 19.0, 95% CI: 1.1-329.8, p = 0.043), or allied-health treatment (OR = 18.2, 95% CI: 2.3-142.4, p = 0.006), decreased balance confidence (OR = 10.9, 95% CI: 2.4-49.3, p = 0.002), and increased fear of falling (OR = 7.5, 95% CI: 2.4-23.8, p = 0.001), compared to two fall circumstances: impact to the arm (OR = 5.0, 95% CI: 2.0-12.1, p = 0.001), and impact to the face, head, or neck (OR = 9.7, 95% CI: 1.2-77.4, p = 0.032).

CONCLUSIONS

Significant falls were generally more associated with fall consequence than fall circumstances.

Are trunk stability and endurance determinant factors for whole-body dynamic balance in physically active young males? A multidimensional analysis

OBJECTIVES

Determine if (a) a better trunk stability and endurance are associated with an improved whole-body dynamic balance, and if (b) the assessment tests can be interchanged within each capability.

METHODS

Sixty-three physically active young males performed three trunk stability (i.e., the lumbopelvic stability, the unstable sitting and the sudden loading sitting tests), three trunk muscle endurance (i.e., the Biering-Sørensen, the side bridge and the front bridge tests) and four whole-body dynamic balance (i.e., the tandem and the single-leg stance, the Y-Balance, and the single-leg triple hop tests) tests two times. After assessing the reliability of the variables, a Pearson correlation analysis was performed.

RESULTS

The correlations between trunk stability and endurance tests with dynamic balance tests were non-significant except for the unstable sitting test with both the tandem (r = 0.502) and the single-leg stance (r = 0.522) tests. Moreover, no relationships were observed between the trunk stability and the trunk muscle endurance tests. Interestingly, no relationships were found between most tests within each capability (i.e., trunk stability, trunk endurance, and dynamic balance) except: (i) the front bridge stability test and the back (r = 0.461) and the side (r = 0.499) bridge stability tests; (ii) the two side bridge endurance tests (r = 0.786); (iii) the tandem and the single-leg stance tests (0.439 ≤ r ≤ 0.463); (iv) the Y-Balance and the single-leg triple hop tests (0.446 ≤ r ≤ 0.477).

CONCLUSION

Better trunk function does not seem to be a relevant factor for dynamic balance in young active males. In this population, specific measures are needed as the test interchangeability is questioned.

Comprehensive linear and nonlinear analysis of the effects of spinning on dynamic balancing ability in Hungarian folk dancers

PURPOSE

In the case of Hungarian folk dancers, it is crucial to maintain correct posture and promptly respond to imbalances. However, traditional dances often lack specific training to develop these skills.

METHODS

In this present study, twelve dancers (8 male, 4 female, age: 21.7 ± 3.6 years) and ten non-dancers subjects forming a control group (6 male, 4 female, age: 21.6 ± 2.87 years) participated. During the measurements a 60-second long bipedal balancing test on the balance board was completed two times, and a spinning intervention was inserted in between the two sessions. The balance capabilities of the two groups were assessed through the characterization of motion on an unstable board, and the analysis of subject's center of mass and head movements.

RESULTS

Dancers applied a more sophisticated and resource-intensive strategy to address the balancing task, yielding a better balancing performance in terms of balance board parameters. By preferring a solid stability in the medio-lateral direction, a greater fluctuation in the anterior-posterior direction can be observed (e.g., significantly lower SampEn values). The overall more successful performance is further evidenced by within-subject comparison since significant differences were observed mostly within the control group. Based on the results, the advanced balancing ability of the folk dancer group is more likely to be acquired through years of experience.

CONCLUSION

The results indicate that additional specialized training could further enhance this ability, encouraging the reliance on poorly memorized corrective movements and reducing the risk of injury.

Do increasingly unstable balance devices provide a graded challenge to bipedal stance in total hip arthroplasty patients?

BACKGROUND

Progressive balance exercises are critical to early functional rehabilitation after total hip arthroplasty (THA) but little is known regarding the challenge imposed by common balance devices.

RESEARCH QUESTION

Do progressively unstable balance devices provide a graded challenge to bipedal stance during early functional rehabilitation in THA patients?

METHODS

Postural control was evaluated in 42 patients (age, 63.7 ± 9.6 years; height, 1.72 ± 0.08 m and body mass, 78.9 ± 14.6 kg) approximately 3 weeks (23 ± 6 days) following unilateral primary THA. Patients were divided into two groups, based on their ability to complete a 20-second unipedal stance test (UPST) on the operated limb. A lumbar mounted inertial sensor monitored center of mass (COM) displacement during bipedal balance conditions involving three balance pads of progressive stiffness and an oscillatory platform, used in isolation and in combination with the most stable balance pad. COM displacement was normalised to bipedal stance on a hard surface. Differences between conditions and patient groups were assessed using a mixed-model analysis of variance.

RESULTS

Twenty patients (48%) were able to complete the UPST on their operated limb. There was a significant effect of balance condition on COM displacement during bipedal stance (F4,160 = 82.6, p < .01). COM displacement was lowest for the oscillatory platform but increased non-linearly across the three balance pads (p < .05). There was no significant difference in COM displacement between THA patients able and unable to complete the UPST.

SIGNIFICANCE

Increasingly compliant balance pads provided a progressive, though nonlinear, challenge to bipedal balance control in THA patients that was greater than that of an oscillating platform and independent of the ability to stand independently on the operated limb. These findings serve as a guide for the design of progressive training programs that enhance balance in THA patients.

Balance-based exercise programs on balance in older adults with mild to moderate dementia: A critically appraised topic

OBJECTIVE

It is well established that exercise programs including balanced-based exercises are practical and beneficial for cognitively healthy older adults. However, there is limited evidence to determine if these types of training regimens are effective for individuals with dementia. We conducted a critical appraisal to determine if the addition of balance-based exercise programs, compared with usual care at residential homes, improved balance in adults diagnosed with mild to moderate dementia.

MATERIALS AND METHODS

Four databases were searched for randomized control trials implementing balanced-based exercise programs with individuals diagnosed with mild to moderate dementia. The articles were evaluated based on the Centre for Evidence Based Medicine level of evidence criteria and appraised using the PEDro scale.

RESULTS

A comprehensive literature search revealed four studies relevant to the clinical question that fit the inclusion and exclusion criteria. All four studies indicated an improvement in balance following a weekly physical therapy program implementing balance-based exercises.

CONCLUSIONS

There is sufficient evidence to suggest that the use of physical therapy programs that include balance-based exercises, performed 1-2 times a week over the course of 12-25 weeks, improves balance in elderly adults with mild to moderate dementia.

Comparison of dynamic and static balance among professional male soccer players by position

PURPOSE

Balance is an important performance aspect of all athletes. The aim of this study was to compare static and dynamic balance in soccer players in different positions.

METHODS

Forty youth and young adult professional soccer players were divided into four groups according to their playing positions: goalkeepers (GK), defenders (DF), midfielders (MF) and forwards (FW) (10 per position). Static and dynamic balance assessed on the dominant and non-dominant legs were measured using a force platform for 30s (static one-leg stand), and "Y Balance Test" (dynamic balance).

RESULTS

GK exhibited greater ML static balance (less ML sway) compared with other players (p < 0.02-0.001). Moreover, results demonstrated better GK dynamic balance compared to DF and FW (p < 0.04-0.006). MF showed better dynamic balance than DF and FW (p < 0.019-0.007) and lower dynamic balance scores were found among DF and FW (p < 0.05).

CONCLUSION

In conclusion, these results affirm position-specific balance performance with greater static and dynamic balance of GK and dynamic balance with MF. It is suggested that evaluation of balance and postural control performance should be considered a relevant part of the position-specific functional evaluation of soccer players.

Comparative Efficacy of Vibration foam Rolling and Cold Water Immersion in Amateur Basketball Players after a Simulated Load of Basketball Game

To compare the efficacy of different recovery strategies (sitting; cold water immersion, CWI; vibration foam rolling, VFR) on the lower extremities of amateur basketball players after the simulated load of a basketball game, we assessed the power, agility, and dynamic balance before and after interventions. Ten amateur basketball players alternately underwent 12 min of sitting, 12 min of CWI at 5 °C, and 12 min of VFR. The power, agility, and dynamic balance were measured immediately post-warm-up, immediately post-game, immediately post-intervention, 1 h after interventions, and 24 h after interventions. To simulate the load of a basketball game, specific movements were designed and implemented. Jump height was measured using a Kistler force plate. Reaction time and dynamic balance score were assessed using the Pavigym agility response system and the Y balance test, respectively. The data were analyzed with a two-way repeated measures analysis of variance (ANOVA). The results showed that the vertical jump height significantly decreased after the CWI intervention compared to the CON and VFR groups (p < 0.001). At 1 h after the intervention, the vertical jump height in the CON group showed delayed recovery compared to the CWI and VFR groups (p = 0.007; p < 0.001). At 24 h after the intervention, the vertical jump height in the CWI group further increased and was significantly different from the CON and VFR groups (p < 0.001; p = 0.005). Additionally, reaction times significantly increased immediately after the CWI intervention (p = 0.004) but showed further recovery at 24 h compared to the CON group (p < 0.001). The dynamic balance score significantly rebounded after the CWI intervention compared to the CON group (p = 0.021), with further improvement at 24 h (p < 0.001). CWI initially showed negative effects, but over time, its recovery effect was superior and more long-lasting. VFR had the best immediate effect on lower limb recovery after the game.

Differences in dynamic balance control based on pain catastrophizing level in individuals with nonspecific chronic low back pain

BACKGROUND

Pain catastrophization (PC) is related to motor control changes in individuals with nonspecific chronic low back pain (NSCLBP). However, differences in dynamic balance control based on the level of PC still remain unclear in these individuals.

OBJECTIVE

The aim of this study was to compare the dynamic balance control between healthy controls and individuals with NSCLBP with high and low PC.

METHODS

Forty individuals with NSCLBP and 20 healthy participants were enrolled in this cross-sectional study. Individuals with NSCLBP were classified into two groups of high and low PC. Dynamic balance control was assessed using the Modified Star Excursion Balance Test (MSEBT), Five-Time Sit-to-Stand Test (FTSST), and Timed Up and Go Test (TUGT).

RESULTS

Statistical analyses showed that mean values of reach distances in the anterior, posteromedial, and posterolateral directions of the MSEBT were significantly lower in individuals with NSCLBP with high PC compared to low PC (p = .04, p = .01, and p = .04, respectively) and healthy controls (p < .001, p = .001, and p = .006, respectively). In addition, for both the FTSS and TUG tests, the mean time was significantly greater in individuals with NSCLBP with high PC compared to low PC (p < .001 and p = .004, respectively) and healthy controls (p < .001).

CONCLUSIONS

Our results showed poor dynamic balance control in individuals with NSCLBP with high PC. This suggests that PC could contribute to the impaired dynamic balance control in individuals with NSCLBP. Combining balance exercises and cognitive-behavioral treatments targeting PC may be useful for the improvement of dynamic balance control in individuals with NSCLBP with high PC.

Effects of jaw clenching on dynamic reactive balance task performance after 1-week of jaw clenching training

Introduction

Good balance is essential for human daily life as it may help to improve the quality of life and reduce the risk of falls and associated injuries. The influence of jaw clenching on balance control has been shown under static and dynamic conditions. Nevertheless, it has not yet been investigated whether the effects are mainly associated with the dual-task situation or are caused by jaw clenching itself. Therefore, this study investigated the effects of jaw clenching on dynamic reactive balance task performance prior to and after 1 week of jaw clenching training. It was hypothesized that jaw clenching has stabilizing effects resulting in a better dynamic reactive balance performance, and these effects are not related to dual-task benefits.

Methods

A total of 48 physically active and healthy adults (20 women and 28 men) were distributed into three groups, one habitual control group (HAB) and two jaw clenching groups (JAW and INT) that had to clench their jaws during the balance tasks at T1 and T2. One of those two groups, the INT group, additionally practiced the jaw clenching task for 1 week, making it familiar and implicit at T2. The HAB group did not receive any instruction regarding jaw clenching condition. Dynamic reactive balance was assessed using an oscillating platform perturbed in one of four directions in a randomized order. Kinematic and electromyographic (EMG) data were collected using a 3D motion capture system and a wireless EMG system, respectively. Dynamic reactive balance was operationalized by the damping ratio. Furthermore, the range of motion of the center of mass (CoM) in perturbation direction (RoM_{CoM_AP} or RoM_{CoM_ML}), as well as the velocity of CoM (V_CoM) in 3D, were analyzed. The mean activity of the muscles relevant to the perturbation direction was calculated to investigate reflex activities.

Results

The results revealed that jaw clenching had no significant effects on dynamic reactive balance performance or CoM kinematics in any of these three groups, and the automation of jaw clenching in the INT group did not result in a significant change either. However, high learning effects, as revealed by the higher damping ratio values and lower V_CoM at T2, were detected for the dynamic reactive balance task even without any deliberate balance training in the intervention phase. In the case of backward perturbation of the platform, the soleus activity in a short latency response phase increased for the JAW group, whereas it decreased for HAB and INT after the intervention. In the case of forward acceleration of the platform, JAW and INT showed a higher tibialis anterior muscle activity level in the medium latency response phase compared to HAB at T1.

Discussion

Based on these findings, it can be suggested that jaw clenching may lead to some changes in reflex activities. However, the effects are limited to anterior-posterior perturbations of the platform. Nevertheless, high learning effects may have overall overweighed the effects related to jaw clenching. Further studies with balance tasks leading to less learning effects are needed to understand the altered adaptations to a dynamic reactive balance task related to simultaneous jaw clenching. Analysis of muscle coordination (e.g., muscle synergies), instead of individual muscles, as well as other experimental designs in which the information from other sources are reduced (e.g., closed eyes), may also help to reveal jaw clenching effects.

Exploring the relationship of static and dynamic balance with muscle mechanical properties of the lower limbs in healthy young adults

There is emerging evidence that mechanical properties of in vivo muscle tissues are associated with postural sway during quiet standing. However, it is unknown if the observed relationship between mechanical properties with static balance parameters generalise to dynamic balance. Thus, we determined the relationship between static and dynamic balance parameters with muscle mechanical properties of the ankle plantar flexors [lateral gastrocnemius (GL)] and knee extensors [vastus lateralis (VL)] in vivo. Twenty-six participants (men = 16, women = 10; age = 23.3 ± 4.4 years) were assessed for static balance [centre of pressure (COP) movements during quiet standing], dynamic balance (reach distances for the Y-balance test) and mechanical properties (stiffness and tone) of the GL and VL measured in the standing and lying position. Significant (p < .05) small to moderate inverse correlations were observed between the mean COP velocity during quiet standing with stiffness (r = -.40 to -.58, p = .002 to .042) and tone (r = -0.42 to -0.56, p = 0.003 to 0.036) of the GL and VL (lying and standing). Tone and stiffness explained 16%-33% of the variance in the mean COP velocity. Stiffness and tone of the VL measured in the lying (supine) condition were also inversely significantly correlated with Y balance test performance (r = -0.39 to -0.46, p = 0.018 to 0.049). These findings highlight that individuals with low muscle stiffness and tone exhibit faster COP movements during quiet standing, indicative of reduced postural control but also reveal that low VL stiffness and tone are associated with greater reach distances in a lower extremity reaching task, indicative of greater neuromuscular performance.

Effects of Attrition Shoes on Balance Control Ability and Postural Stability Following a Single-Leg Drop Jump Landing

The purpose of the study is to determine the influence of lateral-heel-worn shoes (LHWS) on balance control ability through the single-leg drop jump test. The results could be beneficial by preventing lower limb injuries. Eighteen healthy participants performed the single-leg drop jump test. Times to stabilization for ground reaction forces (TTSG) in the anterior/posterior, medial/lateral, and vertical directions were calculated to quantify dynamic balance control ability. Outcome variables of the center of pressure (COP) were used to examine the main effect of LHWS during the static phase. The postural control ability was assessed through time to stabilization for the center of mass (TTSC) in the three directions. TTSG and TTSC for the LHWS group were found to be longer than those for the new shoes (NS) group in the M/L direction (p < 0.05). An increase in the TTS revealed an increased risk of falls during physical activities. However, no significant effects for both TTSG and TTSC were found in the other two directions between LHWS and NS groups. A static phase was cropped using TTSG for each trial, which indicated a phase after participants obtained balance. Outcome measures derived from COP showed no significant effects in the static phase. In conclusion, LHWS weakened balance control ability and postural stability in the M/L direction when compared to the NS group. During the static phase, no significant differences were found between the LHWS group and the NS group in balance control ability and postural stability. Consequently, lateral-worn shoes might increase the risk of fall injuries. The results could serve as an evaluation of shoe degradation for individuals with the aim of avoiding the risk of falls.

Knee extensor force control as a predictor of dynamic balance in healthy adults

BACKGROUND

Previous research has demonstrated that force control in various muscles of the lower limb (measured according to the magnitude of force fluctuations) explains significant variance in static balance. Given the dynamic nature of many functional activities and sports, assessment of balance and its determinants under dynamic conditions is of importance.

RESEARCH QUESTION

Does muscle force control explain significant variance in dynamic balance, as measured using the Y balance test (YBT)?

METHODS

YBT performance and knee extensor muscle force control were measured in 28 healthy participants. The YBT involved stance on the right leg and attempting maximal reach with the left leg in the anterior, posteromedial, and posterolateral directions. Force control was assessed during isometric knee extension contractions of the right leg at 10%, 20% and 40% maximal voluntary contraction (MVC) and was quantified according to the magnitude (using the coefficient of variation [CV]), and the temporal structure (using sample entropy, SampEn; and detrended fluctuation analysis α), of force fluctuations.

RESULTS

Significant correlations were observed for YBT anterior reach and muscle force CV (r = -0.44, P = 0.02) and SampEn (r = 0.47, P = 0.012) during contractions at 40% MVC. A subsequent regression model demonstrated that muscle force CV and SampEn at 40% MVC significantly explained 54% of variance in YBT anterior reach. Significant correlations were also observed for YBT posteromedial reach and MVC (r = 0.39, P = 0.043) and muscle force CV during contractions at 40% MVC (r = -0.51, P = 0.006). The regression model demonstrated that MVC and muscle force CV at 40% MVC significantly explained 53.9% of variance in YBT posteromedial reach.

SIGNIFICANCE

These results are the first to indicate that a moderate amount of variance in dynamic balance can be explained by measures of isometric force control.

Ankle and foot function in female athletes involved in in-water and dry-land sporting activities

BACKGROUND

The stability and mobility of the ankle and foot joints are thought to be improved by cross-training, i.e., transferring the beneficial effects acquired from performing one sporting activity to those required to perform another. This study aimed to investigate the effect of long-term participation with in-water and dry-land sports activities (IWSA, DLSA) on ankle and foot function.

METHODS

The study sample consisted of 28 healthy competitive female athletes involved in IWSA (N.=14) and DLSA (N.=14) for <8 years, as well as 15 females not involved in sporting activities (NISA). The isometric strength of the ankle dorsi flexors (ADF), plantar flexors (APF), and subtalar invertors and evertors (SIN, SEV), the ankle dorsi and plantar flexion, and subtalar/forefoot inversion and eversion passive range of motion (ROM), and the static and dynamic balance were assessed in each participant's supportive lower limb.

RESULTS

IWSA athletes demonstrated significantly greater isometric strength in ADF (P<0.01), SIN (P<0.01), and SEV (P<0.05) compared to DLSA athletes and in ADF (P<0.001), SIN (P<0.01) and SEV (P<0.05) compared to NISA individuals with differences between DLSA athletes and NISA individuals being not significant. Between-groups differences on isometric APF strength, passive ROM of the ankle and foot joints, and postural balance were not significant.

CONCLUSIONS

DLSA athletes could benefit from long-term participation with IWSA, at least in terms of increasing isometric strength of the ankle and foot stabilizers, as their function does not appear to improve after long-term participation with the sports of their choice, at least compared to NISA individuals.

The impact of coordination-based movement education model on balance development of 5-year-old children

With this study, it was aimed to examine the effect of coordination-based movement education model on the development of balance in 5-year-old children. The research was designed with a control group pre-test post-test design, which is one of the quasi-experimental research models. The research group consists of a total of 42 (n = 20 experimental n = 22 control) 5-year-old children formed by using the convenient sampling method, which is one of the purposeful sampling methods. Each participant's age, body weight, body length and lower extremity limb lengths were measured. As a data collection tool and used the three-part Y Balance Test (YBT) platform, which was previously stated to have high reliability (ICC = 0.85-0.93). Reach distances of the participants were measured in three directions, anterior posteromedial and posterolateral. YBT scores were determined by calculating the average and normalized values for lower extremity limb length for each reach direction of the obtained scores, and composite YBT scores were determined by taking the averages of anterior, posteromedial and posterolateral reach distance scores. In order to determine whether the collected data are suitable for normal distribution, Levene test was applied first and it was determined that p > 0.05 for all parameters as a result of the test. Independent sample T-test from parametric tests was used to determine the differences between groups. Paired-group T-test was used to determine within-group differences. According to the results of the research, it was found that the balance motor capacity levels between the experimental and control groups did not differ significantly compared to the pre-test, but there was a significant difference in all reach directions scores in favor of the post-test and experimental group compared to the control group and the pre-test. When the results of the right and left lower extremity ANT, PM, PL and Composite reach distances were examined according to gender, although there was no statistically significant difference, when the averages were considered, it was seen that all parameters were in favor of girls (p > 0.05). As a result, it was concluded that coordination-based movement education model had a positive effect on the balance motor capacities of 5-year-old children.

Validity and reliability of an unstable board for dynamic balance assessment in young adults

Scientific literature is giving greater importance to dynamic balance in fall prevention. Recently, the validity and reliability of the most employed functional tests for dynamic balance assessment has been investigated. Although these functional tests are practical and require minimal equipment, they are inherently subjective, as most do not use instrumented measurement data in the scoring process. Therefore, this study aimed to assess the validity and reliability of an instrumented unstable board for dynamic balance objective assessment in young adults through double-leg standing trials. A test-retest design was outlined with the unstable board positioned over a force platform to collect objective Center of Pressure (CoP) related and kinematic parameters. Fifteen young adults participated in two evaluation sessions (7-day apart) that comprised ten trials per two dynamic conditions (anterior-posterior and medio-lateral oscillations) aiming to maintain the board parallel to the ground. Pearson's correlation coefficient (r) was employed to assess the validity of the kinematic parameters with those derived from the CoP. The test-retest reliability was investigated through Intraclass Correlation Coefficient (ICC), Standard Error of the measurement, Minimal Detectable Change, and Bland-Altman plots. Statistically significant correlations between the CoP and kinematic parameters were found, with r values ranging from 0.66 to 0.95. Good to excellent intrasession (0.89≤ICCs≤0.95) and intersession (0.66≤ICCs≤0.95) ICCs were found for the kinematics parameters. The Bland-Altman plots showed no significant systematic bias. The kinematics parameters derived from the unstable board resulted valid and reliable. The small size of the board makes it a suitable tool for the on-site dynamic balance assessment and a complement of computerized dynamic posturography.

The Effect of Breaking Up Sedentary Time with Calisthenics on Neuromuscular Function: A Preliminary Study

The ageing process results in reduced neuromuscular function. This alongside prolonged sedentary behaviour is associated with decreased muscle strength, force control and ability to maintain balance. Breaking up sedentary time with regular bouts of physical activity has numerous health benefits, though the effects on neuromuscular function are unknown. This study investigated the effect of breaking up sedentary time with calisthenic exercise on neuromuscular function. 17 healthy adults (33 ± 13.1 years), who spent ≥6 h/day sitting, were assigned to a four-week calisthenics intervention (n = 8) or control group (n = 9). The calisthenics intervention involved performing up to eight sets of exercises during the working day (09:00-17:00); with one set consisting of eight repetitions of five difference exercises (including squats and lunges). Before and immediately after the intervention, measures of knee extensor maximal voluntary contraction (MVC) and submaximal force control (measures of the magnitude and complexity of force fluctuations), and dynamic balance (Y balance test) were taken. The calisthenics intervention resulted in a significant increase in knee extensor MVC (p = 0.036), significant decreases in the standard deviation (p = 0.031) and coefficient of variation (p = 0.016) of knee extensor force fluctuations during contractions at 40% MVC, and a significant increase in Y balance test posterolateral reach with left leg stance (p = 0.046). These results suggest that breaking up sedentary time with calisthenics may be effective at increasing muscle strength, force steadiness and dynamic balance all of which might help reduce the effects of the ageing process.

Kinetic Effects of 6 Weeks' Pilates or Balance Training in College Soccer Players with Chronic Ankle Instability

Lateral ankle sprain (LAS) is a common sports injury that frequently occurs in active individuals. LAS is characterized by a high recurrence rate, with a large proportion of patients progressing to chronic ankle instability (CAI). Pilates exercises have provided positive results in health care and in rehabilitation. This study compared Pilates training (PT) with traditional balance training (BT) in patients with CAI. Fifty-one college football players with CAI, divided into PT (n = 26) and BT (n = 25) groups, were included in the study. The groups performed PT or BT training as assigned, three times per week for 6 weeks. Isokinetic ankle strength, one-leg hop tests, Y-balance test (YBT), and foot and ankle outcome score (FAOS) were evaluated before and after training. There were considerable improvements in both the PT and BT groups after training. Group and time comparisons revealed that the PT group achieved better triple hop test results than the BT group, whereas the BT group exhibited a greater improvement in YBT posteromedial and posterolateral reach distances. In athletes with CAI, both PT and BT effectively improved symptoms and function. These findings suggest that ankle strength, balance, and core stability should be comprehensively evaluated and targeted in CAI rehabilitation programs.

Physical active lifestyle promotes static and dynamic balance performance in young and older adults

Although regular physical activity exposure leads to positive postural balance control (PBC) adaptations, few studies investigated its effects, or the one of inactivity, on PBC in populations of different age groups. Thus, this study investigated the impact of a physically active lifestyle on static and dynamic PBC in young and older adults. Thirty-five young physically active subjects (YA), 20 young sedentary subjects (YS), 16 physically active older adults (OA), and 15 sedentary older adults (OS) underwent a static and a dynamic PBC assessment. A force platform and an instrumented proprioceptive board were employed to measure the center of pressure (COP) trajectory and the anteroposterior oscillations, respectively. In static conditions, no significant differences were detected among groups considering the overall postural balance performance represented by the area of confidence ellipse values. Conversely, the YA highlighted a higher efficiency (i.e., lower sway path mean velocity) in PBC maintenance compared to the other groups (YA vs OA: p = 0.0057, Cohen’s d = 0.94; YA vs OS p = 0.043, d = 1.07; YA vs YS p = 0.08, d = 0.67). OS exhibited an overall worse performance in dynamic conditions than YA and YS. Surprisingly, no differences were found between YS and OA for all the static and dynamic parameters considered. In conclusion, our results suggest that a physically active lifestyle may promote static and dynamic balance performance in young and older adults, thus with potentially positive effects on the age-related decline of postural balance performance. Dynamic PBC assessment seems more sensitive in detecting differences between groups than the static evaluation.

Investigation of Joint Position Sense and Balance in Individuals With Chronic Idiopathic Neck Pain: A Cross-Sectional Study

OBJECTIVE

The aim of this study was to determine the relationship between joint position sense and static and dynamic balance in female patients with chronic neck pain compared with healthy controls.

METHODS

The study sample comprised 25 female patients with chronic neck pain and 25 healthy (asymptomatic) female controls. Pain severity with the visual analog scale, joint position sense with the laser pointer method, static balance with the Single-Leg Balance Test, and dynamic balance with the Y Balance Test were assessed.

RESULTS

The deviation in cervical joint position sense was greater in extension (P < .001), right rotation (P < .001), and left lateral rotation (P < .05) in the patients with chronic neck pain compared with the healthy controls. The results of the patients with chronic neck pain were worse than the healthy controls in the Single-Leg Balance Test with both eyes open (P < .05) and eyes closed (P < .05). The patients with chronic neck pain had worse dynamic balance only in the anterior direction reach of the left leg (P < .05).

CONCLUSION

Cervical joint position sense and static balance were worse in female patients with chronic idiopathic neck pain when compared with asymptomatic controls. Dynamic balance in all other directions except for the anterior direction was not negatively affected in individuals with chronic idiopathic neck pain.

Young Individuals Are More Stable and Stand More Upright When Using Rollator Assistance During Standing up and Sitting Down

Four-wheeled walkers or rollators are often used to assist older individuals in maintaining an independent life by compensating for muscle weakness and reduced movement stability. However, limited biomechanical studies have been performed to understand how rollator support affects posture and stability, especially when standing up and sitting down. Therefore, this study examined how stability and posture change with varying levels of rollator support and on an unstable floor. The aim was to collect comprehensive baseline data during standing up and sitting down in young participants. In this study, 20 able-bodied, young participants stood up and sat down both 1) unassisted and assisted using a custom-made robot rollator simulator under 2) full support and 3) touch support. Unassisted and assisted performances were analyzed on normal and unstable floors using balance pads with a compliant surface under each foot. Using 3D motion capturing and two ground-embedded force plates, we compared assistive support and floor conditions for movement duration, the relative timing of seat-off, movement stability (center of pressure (COP) path length and sway area), and posture after standing up (lower body sagittal joint angles) using ANOVA analysis. The relative event of seat-off was earliest under full support compared to touch and unassisted conditions under normal but not under unstable floor conditions. The duration of standing up and sitting down did not differ between support conditions on normal or unstable floors. COP path length and sway area during both standing up and sitting down were lowest under full support regardless of both floor conditions. Hip and knee joints were least flexed under full support, with no differences between touch and unassisted in both floor conditions. Hence, full rollator support led to increased movement stability, while not slowing down the movement, during both standing up and sitting down. During standing up, the full support led to an earlier seat-off and a more upright standing posture when reaching a stable stance. These results indicate that rollator support when handles are correctly aligned does not lead to the detrimental movement alterations of increased forward-leaning. Future research aims to verify these findings in older persons with stability and muscle weakness deficiencies.

Physical activity does not impact mediolateral margin of stability across a range of postural-perturbing conditions in young adults

BACKGROUND

The maintenance of stability during walking is critical for successful locomotion. While targeted balance training can improve stability, it is unclear how simply meeting recommended physical activity guidelines may impact dynamic stability in healthy young adults.

RESEARCH QUESTION

Examining the differences in the mediolateral margin of stability (ML-MOS) and the variability of the ML-MOS in physically active and inactive young adults across a range of stability-challenging walking tasks METHOD: Twenty-one physically active and twenty inactive young adults completed four experimental walking conditions: (1) Overground Walking, (2) Tandem Walking, (3) Beam Walking, and (4) Stepping-Stones. The ML-MOS and coefficient of variation of the ML-MOS were calculated at each heel strike while participants walked at their preferred walking speed. A two-way mixed-effects ANOVA was conducted to examine the effects of group and condition and their interaction on ML-MOS and ML-MOS variability RESULTS: Neither the ML-MOS nor the variability of the ML-MOS was significantly different between physically active and physically inactive young adults during any experimental walking conditions. A significant main effect of the experimental walking condition was observed, with the ML-MOS decreasing from overground walking to the tandem and beam walking conditions. The ML-MOS also became more variable in the tandem, beam, and stepping-stones conditions than in overground gait.

SIGNIFICANCE

Physical activity status did not influence frontal plane dynamic balance in healthy young adults, even in stability-challenging environments. Conditions that constrain step width, such as tandem and beam walking, are adequate for challenging frontal plane dynamic balance and indicate that trunk kinematics may be adjusted when step width is constrained.

Preliminary Analysis of Closed Kinetic Chain Upper Extremity Stability Test Differences Between Healthy and Previously Injured/In-Pain Baseball Pitchers

BACKGROUND

A comprehensive examination of the kinetic chain during an overhead athlete's upper extremity assessment, such as the closed kinetic chain upper extremity stability test (CKCUEST), may help clinicians identify potential upper extremity dysfunction.

HYPOTHESIS

Body position observed on dominant and nondominant hand touch during a CKCUEST trial differs between players with previous injury/pain history compared with healthy counterparts.

STUDY DESIGN

Descriptive laboratory study.

LEVEL OF EVIDENCE

Level 5.

METHODS

Seventeen baseball pitchers were recruited to participate (18.03 ± 2.01 years; 185.40 ± 6.57 cm; 83.92 ± 13.87 kg). A medical history questionnaire was used to separate participants into groups, either previous injury/pain or healthy. Kinematic and kinetic data were collected on the participants performing the CKCUEST with an electromagnetic tracking system. Kinematics were analyzed using a pair of 1-way multivariate analyses of variance (MANOVAs).

RESULTS

The MANOVA for nondominant hand touch in the CKCUEST revealed a significant difference in lumbopelvic-hip complex (LPHC) kinematics between previously injured/pain group and healthy group (Λ = 0.37; F_4,12 = 5.12; P = 0.01).

CONCLUSIONS

The previously injured/pain group displayed less pelvic axial rotation and dominant hip abduction during the nondominant touch indicating more LPHC stability during the nondominant touch. In conclusion, differences were observed in LPHC kinematics during the CKCUEST nondominant touch between a healthy and previously injured/pain group perhaps due to the increased awareness provided through rehabilitative programs for the previously injured/pain group.

CLINICAL RELEVANCE

Clinicians can use this information to help address kinetic chain movement efficiency within baseball pitchers. This study provides evidence of LPHC kinematic differences during the nondominant touch of baseball pitchers and may enhance the use of the CKCUEST as a return-to-play assessment.

Effects of High-Intensity Aquatic or Bicycling Training in Athletes with Unilateral Patellofemoral Pain Syndrome

Patellofemoral pain syndrome (PFPS) is one of the most common overuse injuries experienced by athletes. It is characterized by pain and functional deficits that lead to decreased performance, thereby limiting sports activity. Therefore, optimal training interventions are required to improve physical fitness and function while minimizing pain due to PFPS. This study aimed to compare and analyze the effects of high-intensity aquatic training (AT) and bicycling training (BT) in male athletes with PFPS. Fifty-four athletes with PFPS were divided into AT and BT intervention groups. Intervention training was conducted three times per week for 8 weeks. Cardiorespiratory fitness was evaluated using the graded exercise test (GXT) based on peak oxygen uptake (VO₂ peak), and anaerobic threshold. For the knee strength test, extension and flexion were performed and measured using isokinetic equipment. One-leg hop tests and the Y-balance test (YBT) were performed to evaluate dynamic balance, and the International Knee Documentation Committee (IKDC) scoring system was used for subjective knee evaluation. The GXT, YBT, and IKDC scores were reported according to the group and duration of the intervention. After training, VO₂ peak, YBT, knee extension strength, and IKDC score improved significantly in both the AT and BT groups compared with the pre-training values. Furthermore, the AT group exhibited significant improvement compared with the BT group. We demonstrated that AT and BT effectively improved the symptoms and muscle strength of athletes with PFPS who were only able to engage in limited high-intensity field training. AT produced a modestly better effect than BT.

Influence of Controlled Stomatognathic Motor Activity on Sway, Control and Stability of the Center of Mass During Dynamic Steady-State Balance—An Uncontrolled Manifold Analysis

Multiple sensory signals from visual, somatosensory and vestibular systems are used for human postural control. To maintain postural stability, the central nervous system keeps the center of mass (CoM) within the base of support. The influence of the stomatognathic motor system on postural control has been established under static conditions, but it has not yet been investigated during dynamic steady-state balance. The purpose of the study was to investigate the effects of controlled stomatognathic motor activity on the control and stability of the CoM during dynamic steady-state balance. A total of 48 physically active and healthy adults were assigned to three groups with different stomatognathic motor conditions: jaw clenching, tongue pressing and habitual stomatognathic behavior. Dynamic steady-state balance was assessed using an oscillating platform and the kinematic data were collected with a 3D motion capturing system. The path length (PL) of the 3D CoM trajectory was used for quantifying CoM sway. Temporal dynamics of the CoM movement was assessed with a detrended fluctuation analysis (DFA). An uncontrolled manifold (UCM) analysis was applied to assess the stability and control of the CoM with a subject-specific anthropometric 3D model. The statistical analysis revealed that the groups did not differ significantly in PL, DFA scaling exponents or UCM parameters. The results indicated that deliberate jaw clenching or tongue pressing did not seem to affect the sway, control or stability of the CoM on an oscillating platform significantly. Because of the task-specificity of balance, further research investigating the effects of stomatognathic motor activities on dynamic steady-state balance with different movement tasks are needed. Additionally, further analysis by use of muscle synergies or co-contractions may reveal effects on the level of muscles, which were not visible on the level of kinematics. This study can contribute to the understanding of postural control mechanisms, particularly in relation to stomatognathic motor activities and under dynamic conditions.

Learning a new balance task: the influence of prior motor practice on training adaptations

Prior motor experience is thought to aid in the acquisition of new skills. However, studies have shown that balance training does not promote learning of a subsequent balance task. These results stand in contrast to the learning-to-learn paradigm, which is well described for other tasks. We therefore tested if a coordinative affinity between tasks is needed to achieve a learning-to-learn for balance control.Three groups trained different motor tasks during training phase1 (coordination ladder (COOR); bipedal wobble board (2WB); single-leg wobble board (1WB)). During training phase2, all groups trained a tiltboard balance task. Task-specific and transfer effects were evaluated for phase1. A potential learning-to-learn effect was evaluated by comparing the acquisition rates from phase2 for the tiltboard task that was used for training and testing.The results indicate task-specific adaptations after phase1 for 1WB. In contrast, 2WB showed similar improvements than 1WB and COOR (effect sizes: -0.31 to -0.38) when tested on the wobble board with bipedal stance indicating no task-specific improvement for 2WB. For phase2, the linear regression analysis showed larger adaptations for 1WB and 2WB when compared to COOR. This effect implies some uncertainty due to overlapping confidence intervals.Task-specific adaptations after phase1 were found for 1WB but not 2WB. It is discussed that the difficulty of the training task could explain these contrasting results. During phase2, larger adaptations were found for both groups that trained balance tasks during phase1. Thus, despite some uncertainty, prior balance training appears to promote adaptations of a subsequently learned balance task.

Does induced fatigue alter dynamic balance in athletes? A systematic review

OBJECTIVES

To determine the influence of induced fatigue on dynamic balance in healthy athletes.

DESIGN

Systematic review.

DATA SOURCES

PUBMED, MEDLINE, CINAHL, Sports Discus, and the Cochrane library from onset to May 28, 2019.

ELIGIBILITY CRITERIA

Eligible studies included any study examining the effects of induced-fatigue on dynamic balance, as measured by the SEBT/YBT, in healthy athletic populations. Studies with a low risk of bias were considered scientifically admissible for a best evidence synthesis.

RESULTS

Fifteen studies with low risk of bias were included - seven investigated recreational athletes while eight focused on competitive athletes. In the recreational population, five of the studies found significant decrease in dynamic balance following the fatiguing intervention. However, the remaining two concluded with insignificant changes. As for the competitive population, three studies showed significant effects of induced fatigue on dynamic balance, while five showed no effects.

CONCLUSION

There are conflicting results regarding the effects of induced fatigue on dynamic balance. The majority of studies focused on competitive athletes found that fatigue did not alter their dynamic balance. Per contra, the majority of studies focused on recreational athletes concluded the opposite - fatigue did indeed affect dynamic balance.

Influence of controlled masticatory muscle activity on dynamic reactive balance

BACKGROUND

The influence of the stomatognatic system on human posture control has been investigated under static conditions, but the effects on dynamic balance have not yet been considered.

OBJECTIVE

Investigating the influence of different functional stomatognatic activities (jaw clenching (JAW), tongue pressing (TON) and habitual jaw position (HAB)) on postural performance during a dynamic reactive balance task.

METHODS

Forty-eight physically active and healthy adults were assigned to three groups differing in oral-motor tasks (JAW, TON or HAB). Dynamic reactive balance was assessed by an oscillating platform which was externally perturbed in four directions. Performance was quantified by means of Lehr's damping ratio. Mean speeds of the selected anatomical regions (head, trunk, pelvis, knee and foot) were analysed to determine significant performance differences.

RESULTS

The groups differed significantly in balance performance in direction F (i.e., forwards acceleration of the platform). Post hoc tests revealed that the JAW group had significantly better performance compared with both the HAB and TON groups. Better performance was associated with a decreased mean speed of the analysed anatomical regions.

CONCLUSION

JAW can improve dynamic reactive balance but the occurrence of positive effects seems to be task-specific and not general. TON seems not to have any observable effects on dynamic reactive balance performance, at least when evaluating it with an oscillating platform. JAW might be a valuable strategy which could possibly reduce the risk of falls in elderly people; however, further investigations are still needed.

Identification of Neuromuscular Performance Parameters as Risk Factors of Non-contact Injuries in Male Elite Youth Soccer Players: A Preliminary Study on 62 Players With 25 Non-contact Injuries

Introduction: Elite youth soccer players suffer increasing numbers of injuries owing to constantly increasing physical demands. Deficits in neuromuscular performance may increase the risk of injury. Injury risk factors need to be identified and practical cut-off scores defined. Therefore, the purpose of the study was to assess neuromuscular performance parameters within a laboratory-based injury risk screening, to investigate their association with the risk of non-contact lower extremity injuries in elite youth soccer players, and to provide practice-relevant cut-off scores.

Methods: Sixty-two elite youth soccer players (age: 17.2 ± 1.1 years) performed unilateral postural control exercises in different conditions, isokinetic tests of concentric and eccentric knee extension and knee flexion (60°/s), isometric tests of hip adduction and abduction, and isometric tests of trunk flexion, extension, lateral flexion and transversal rotation during the preseason period. Non-contact lower extremities injuries were documented throughout 10 months. Risk profiling was assessed using a multivariate approach utilizing a Decision Tree model [Classification and Regression Tree (CART) method].

Results: Twenty-five non-contact injuries were registered. The Decision Tree model selected the COP sway, the peak torque for knee flexion concentric, the functional knee ratio and the path of the platform in that hierarchical order as important neuromuscular performance parameters to discriminate between injured and non-injured players. The classification showed a sensitivity of 0.73 and a specificity of 0.91. The relative risk was calculated at 4.2, meaning that the risk of suffering an injury is four times greater for a player, who has been classified as injured by the Decision Tree model.

Conclusion: Measuring static postural control, postural control under unstable condition and the strength of the thigh seem to enable a good indication of injury risk in elite youth soccer players. However, this finding has to be taken with caution due to a small number of injury cases. Nonetheless, these preliminary results may have practical implications for future directions in injury risk screening and in planning and developing customized training programs to counteract intrinsic injury risk factors in elite youth soccer players.

Quantitative assessment of the level of instability of a single-plane balance platform

BACKGROUND

Balance training on unstable surfaces is widely used in medicine and sports. The main disadvantage of balance platforms is weakly definable assessment of the level of instability (IL) they create.

OBJECTIVE

To evaluate the mechanical characteristics of a suspended single-plane instability balance platform which determines quantitative instability characteristics.

METHODS

Three criteria influencing the IL were evaluated: 1. The displacement of the platform board by changing the position of the object on the board; 2. Amount of force required for board displacement; 3. The vibration damping of the platform.

RESULTS

1. 1IL the displacement of the object on the board affected 0.66 cm. the displacement of the board relative to the platform frame; 2IL - 0.79 cm; 3IL - 0.91 cm.; 2. A force of 2.64 is required for a board displacement of 1IL compared to 2IL and 5.76 times that of 3IL. 3. Damping factor 1IL - 0.015, 2IL - 0.006, 3IL - 0.003.

CONCLUSIONS

1. The longer the suspension, the change in the position of the object on the board affects the greater movement of the board relative to the platform. 2. Different IL can be compared with each other depending on how different the force required to cause the board to move. 3. The platform dampens vibrations weakly, but the damping between 1 and 3 IL differs about 5 times.

A review of center of pressure (COP) variables to quantify standing balance in elderly people: Algorithms and open-access code

Postural control is often quantified by recording the trajectory of the center of pressure (COP)-also called stabilogram-during human quiet standing. This quantification has many important applications, such as the early detection of balance degradation to prevent falls, a crucial task whose relevance increases with the aging of the population. Due to the complexity of the quantification process, the analyses of sway patterns have been performed empirically using a number of variables, such as ellipse confidence area or mean velocity. This study reviews and compares a wide range of state-of-the-art variables that are used to assess the risk of fall in elderly from a stabilogram. When appropriate, we discuss the hypothesis and mathematical assumptions that underlie these variables, and we propose a reproducible method to compute each of them. Additionally, we provide a statistical description of their behavior on two datasets recorded in two elderly populations and with different protocols, to hint at typical values of these variables. First, the balance of 133 elderly individuals, including 32 fallers, was measured on a relatively inexpensive, portable force platform (Wii Balance Board, Nintendo) with a 25-s open-eyes protocol. Second, the recordings of 76 elderly individuals, from an open access database commonly used to test static balance analyses, were used to compute the values of the variables on 60-s eyes-open recordings with a research laboratory standard force platform.

The Effect of Combining Plyometrics Exercises and Balance Exercises in Improving Dynamic Balance among Female College Athletes: A Randomized Controlled Trial

INTRODUCTION

Plyometrics and balance exercises have been shown to reduce lower limb injury incidence. The effects of combining these exercises on dynamic balance have not been investigated.

OBJECTIVE

This study aimed to evaluate the effect of plyometrics and balance exercises and a combination of both exercises on postural stability among female athletes compared to those who did not perform any specific exercise (control).

DESIGN

Randomized controlled trial.

SETTING

Sports Medicine Laboratory.

PARTICIPANTS

Two hundred female athletes aged 21.9±2.4 years were randomly assigned to a plyometrics exercises group (n = 50), a balance exercises group (n = 50), a combination of both exercises group (n = 50), or a control group (n = 50). One hundred seventy-nine female college athletes completed the study.

INTERVENTIONS

Plyometrics exercises, balance exercises and a combination of both exercises.

OUTCOME MEASURES

Limits of stability, which was assessed using the Biodex Stability System to assess the performance of the dynamic balance. It was measured pre and post-intervention after six weeks.

RESULTS

There were no differences in baseline data between groups (p = .557). All groups showed significant improvements in limits of stability (p < .001). The most marked improvement in the limits of stability was shown in the combination group compared to the control group (MD = 4.1 %, 95% CI [2.8, 5.3], p < .001).

CONCLUSIONS

Combining plyometrics and balance exercises significantly increases the dynamic balance performance post-intervention among female athletes compared to the control group. This article is protected by copyright. All rights reserved.

Are Static and Dynamic Postural Balance Assessments Two Sides of the Same Coin? A Cross-Sectional Study in the Older Adults

The aim of this study was to investigate if the combination of static and dynamic postural balance assessments gives more accurate indications on balance performance among healthy older adults. We also aimed at studying the effect of a dual-task condition on static and dynamic postural balance control. Fifty-seven healthy older adults (age = 73.2 ± 5.0 year, height = 1.66 ± 0.08 m, and body mass = 72.8 ± 13.8 kg) completed the study. Static and dynamic balance were assessed both in single-task and dual-task conditions through a force plate and an oscillating platform. The dominant handgrip strength was also measured with a dynamometer. Pearson’s correlation revealed non-statistically significant correlations between static and dynamic balance performance. The dual-task worsened the balance performance more in the dynamic (+147.8%) than in the static (+25.10%, +43.45%, and +72.93% for ellipse area, sway path, and AP oscillations, respectively) condition (p < 0.001). A weak correlation was found between dynamic balance performance and handgrip strength both in the single (p < 0.05; r = −0.264) and dual (p < 0.05; r = −0.302) task condition. The absence of correlations between static and dynamic balance performance suggests including both static and dynamic balance tests in the assessment of postural balance alterations among older adults. Since cognitive-interference tasks exacerbated the degradation of the postural control performance, dual-task condition should also be considered in the postural balance assessment.

Adaptability to Balance Perturbations During Walking as a Potential Marker of Falls History in Older Adults

Given that falls most commonly occur during walking due to unexpected balance perturbations like trips and slips, walking-based balance assessment including walking stability and adaptability to such perturbations could be beneficial for fall risk assessment in older adults. This cross-sectional study reanalyzed data from two larger studies conducted with the same walking protocol. Participants completed unperturbed walking trials at speeds of 0.4 m/s up to 1.8 m/s in 0.2 m/s steps. Ten unannounced treadmill belt acceleration perturbations were then applied while participants walked at equivalent stability, assessed using the margins of stability. Retrospective (12 months) falls incidence was collected to divide participants into people with and without a history of falls. Twenty older adults (mean age 70.2 ± 2.9 years) were included in this analysis; eight people with one or more recent falls and 12 people without, closely matched by sex, age and height. No significant differences were found in unperturbed walking parameters or their variability. Overall perturbation-recovery step behavior differed slightly (not statistically significant) between the groups after the first perturbation and differences became more pronounced and significant after repetition of perturbations. The No-Falls group significantly reduced the number of recovery steps needed across the trials, whereas the Falls group did not show these improvements. People with a previous fall tended to have slightly delayed and more variable recovery responses after perturbation compared to non-fallers. Non-fallers demonstrate more signs of adaptability to repeated perturbations. Adaptability may give a broader indication of the ability of the locomotor system to respond and improve responses to sudden walking perturbations than unperturbed walking variability or recovery to a single novel perturbation. Adaptability may thus be a more useful marker of falls history in older adults and should be considered in further research.

Gymnastics Experience Enhances the Development of Bipedal-Stance Multi-Segmental Coordination and Control During Proprioceptive Reweighting

Performance and control of upright bipedal posture requires a constant and dynamic integration of relative contributions of different sensory inputs (i. e., sensory reweighting) to enable effective adaptations as individuals face environmental changes and perturbations. Children with gymnastic experience showed balance performance closer to that of adults during and after proprioceptive alteration than children without gymnastic experience when their center of pressure (COP) was analyzed. However, a particular COP sway can be achieved through performing and coordinating different postural movements. The aim of this study was to assess how children and adults of different gymnastic experience perform and control postural movements while they have to adjust balance during and after bilateral tendon vibration. All participants were equipped with spherical markers attached to their skin and two vibrators strapped over the Achilles tendons. Bipedal stance was performed in three 45-s trials in two visual conditions (eyes open, EO, and eyes closed, EC) ordered randomly in which vibration lasted 10 s. Posture movements were analyzed by a principal component analysis (PCA) calculated on normalized and weighted markers coordinates. The relative standard deviation of each principal movement component (principal position, PP-rSTD) quantified its contribution to the whole postural movements, i.e., quantified the coordinative structure. The first (principal velocities, PV-rSTD) and second (principal accelerations, PA-rSTD) time-derivatives characterized the rate-dependent sensory information associated with and the neuromuscular control of the postural movements, respectively. Children without gymnastic experience showed a different postural coordinative structure and different sensory-motor control characteristics. They used less ankle movements in the anterior-posterior direction but increased ankle movements in medio-lateral direction, presented larger hip and trunk velocities, and exhibited more hip actions. Gymnastic experience during childhood seemed to benefit the development of proprioceptive reweighting processes in children, leading to a more mature form of coordinating and controlling posture similarly to adults.

Balance abilities of junior ice hockey players

BACKGROUND

Postural control is required during various fast-paced and offensive ice hockey actions, and therefore seems to be an important component in ice hockey performance.

METHODS

Data were collected from two ice hockey teams with differing performance levels. The higher-performance team consisted of 26 players (with ages of 16.3±0.9 y, heights of 178.26±6.71 cm, and weights of 74.3±9.6 kg). The lower-performance team consisted of 19 players (with ages of 16.2±1.8 y, heights of 176.11±9.81 cm, and weights of 68.7±13.9 kg). Each participant performed six unilateral stances under static conditions on a balance pad placed on a force platform and five bilateral stances under dynamic conditions using a wobble board placed on the force platform.

RESULTS

The higher-level players performed better in the unilateral static stance task in both the anterior-posterior direction and the medial-lateral direction (with a P value of P<0.001), and total velocity (P=0.001). The higher-level players also performed better in both the anterior-posterior and medial-lateral directions, and total velocity (with P value of P<0.001), in the bilateral dynamic stance task and therefore performed significantly better than the lower-level players.

CONCLUSIONS

Hockey players who possess a highly developed postural control strategy have a superior ability to compensate for unexpected postural disturbances and collisions, and thus possess a strong competitive advantage. Therefore, testing the balance abilities of hockey players under static and dynamic conditions may be useful for evaluating their competitive performance levels.

Effects of a 16-week multimodal exercise program on gait performance in individuals with dementia: a multicenter randomized controlled trial

Background

There is a high prevalence of gait impairments in individuals with dementia (IWD). Gait impairments are associated with increased risk of falls, disability, and economic burden for health care systems. Only few studies have investigated the effectiveness of physical activity on gait performance in IWD, reporting promising but inconsistent results. Thus, this study aimed to investigate the effectiveness of a multimodal exercise program (MEP) on gait performance in IWD.

Methods

In this parallel-group randomized controlled trial, we enrolled 319 IWD of mild to moderate severity, living in care facilities, aged ≥ 65 years, and being able to walk at least 10 m. The control group (n = 118) received conventional treatment, whereas the intervention group (n = 201) additionally participated in a 16-week MEP specifically tailored to IWD. We examined the effects of the MEP on spatiotemporal gait parameters and dual task costs by using the gait analysis system GAITRite. Additionally, we compared characteristics between positive, non-, and negative responders, and investigated the impact of changes in underlying motor and cognitive performance in the intervention group by conducting multiple regression analyses.

Results

Two-factor analyses of variance with repeated measurements did not reveal any statistically significant time*group effects on either spatiotemporal gait parameters or dual task costs. Differences in baseline gait performance, mobility, lower limb strength, and severity of cognitive impairments were observed between positive, non-, and negative responders. Positive responders were characterized by lower motor performance compared to negative and non-responders, while non-responders showed better cognitive performance than negative responders. Changes in lower limb strength and function, mobility, executive function, attention, and working memory explained up to 39.4% of the variance of changes in gait performance.

Conclusions

The effectiveness of a standardized MEP on gait performance in IWD was limited, probably due to insufficient intensity and amount of specific walking tasks as well as the large heterogeneity of the sample. However, additional analyses revealed prerequisites of individual characteristics and impacts of changes in underlying motor and cognitive performance. Considering such factors may improve the effectiveness of a physical activity intervention among IWD.

Trial registration

DRKS00010538 (German Clinical Trial Register, date of registration: 01 June 2016, retrospectively registered, https://www.drks.de/drks_web/setLocale_EN.do).

An Overview of the Beneficial Effects of Exercise on Health and Performance

Life expectancy is steadily increasing in modern societies, and so are noncommunicable diseases such as cardiovascular diseases, diabetes, obesity, and cancer, accounting for more than 70% of all deaths globally. The costs associated with these diseases are enormous, but it has been estimated that the majority of these noncommunicable diseases are preventable. In addition to an unhealthy diet, tobacco use, and harmful use of alcohol, physical inactivity is a key risk factor. Consequently, physical activity is a logical remedy, and in this chapter an overview of the numerous beneficial effects of physical activity on health and performance is given.The chapter is divided into three parts: First, the basics of physical activity and exercise are discussed, for instance exercise classification, exercise intensity operationalization, energy supply, and the acute effects of exercise such as blood flow redistribution and increased cardiac output. In the second part, the effects of exercise on physical performance are summarized. Specifically, it is discussed how endurance, strength, power, and balance can be improved. This discussion includes recommendations regarding the type, intensity, and duration of the exercise leading to improvements in one of these aspects of physical performance, as well as the mechanisms causing these adaptations. In the third part, the beneficial effects of physical activity on physical and mental health are outlined, with particular attention to cardiovascular diseases, the metabolic syndrome, musculoskeletal diseases, mood, anxiety, depression, and dementia.It can be concluded that with adequate programming, regular physical activity is an effective way to improve physical performance, improve physical and mental health, and reduce the risk factors for many noncommunicable diseases such as cardiovascular diseases, metabolic syndrome, sarcopenia, osteoporosis, and depression. In contrast to medication, physical exercise has no negative side effects, costs very little, and targets many health issues at once. If the multitude of beneficial effects of regular exercise were to be combined in a single low-cost drug, it would be prescribed for almost all types of physical and mental health issues.

Development of a Smartphone-Based Balance Assessment System for Subjects with Stroke

Stroke is a cerebral artery disease that negatively affects activities of daily living (ADLs) and quality of life (QoL). Smartphones have demonstrated strong potential in assessing balance performance. However, such smartphone-based tools have thus far not been applied to stroke survivors. The purpose of this study was to develop a smartphone-based balance assessment system for subjects who have experienced strokes and evaluate the system feasibility. The smartphone-based balance assessment application was developed with Android Studio, and reliability and validity tests were conducted. The smartphone was used to record data using a built-in accelerometer and gyroscope, and increased changes represented greater instability. Six postures were tested for 30 s each. Ten healthy adults were recruited in the reliability test, and the intraclass correlation coefficient (ICC) was used to analyze the within-day and between-day reliabilities. Eight subjects with chronic stroke and eight healthy adults were recruited for the validity test, in which balance performance was compared to represent the application validity. The ICC values of the reliability tests were at least 0.76 (p = 0.00). The acceleration data exhibited no difference between individuals who have experienced stroke and healthy subjects; however, all six postures were found to differ significantly between the two groups in the gyroscope data. The study demonstrates that the smartphone application provides a convenient, reliable, and valid tool for the balance assessments of subjects who have experienced chronic stroke.

Single-Leg Balance Performance in Sub-Elite Young Soccer Players and Swimmers as a Function of Age and Sports Experience

The present study investigated if accumulated, advanced, regular soccer practice (balance-demanding exercise) compared to regular swim practice (non-balance–demanding exercise) induces a more pronounced functional specialization in postural control. Therefore, single-leg balance performance in sub-elite young soccer players (under 13 [U13]: n = 16; U15: n = 18; U19: n = 15), and sub-elite young swimmers (U13: n = 7; U15: n = 4; U19: n = 5) was tested in different balance task conditions (i.e., static and dynamic balance on firm and foam surface). All athletes practiced 3–10 times per week. Single-leg balance of the dominant and non-dominant leg was measured using a force plate. The standard deviation of the center of pressure displacements in anterior-posterior and medio-lateral directions were used as dependent variables. Irrespective of age groups and type of sport, the results failed to indicate significant leg differences in single-leg balance performance. The soccer players showed significant better single-leg balance performance in anterior-posterior direction in the dynamic balance test on the firm and foam surface compared to the swimmers. Functional specialization was accompanied by the type of sport but not by accumulated practice.

Standing balance of professional ballet dancers and non-dancers under different conditions

Ballet training has been reported to positively influence balance ability. It is not entirely clear how improved balance ability manifests under standing conditions with different demands on postural control. The aim of the study was to compare balance of ballet dancers and non-dancers in a unipedal stance under different conditions. Twenty-five professional ballet dancers and twenty-five controls completed four unipedal standing balance tests: firm surface with eyes open and closed; foam mat surface with eyes open; and firm surface with eyes open immediately after performing ten 360° whole-body turns. The centre of pressure (COP) data were obtained with a force platform and the direction-specific standard deviations, velocities, and sample entropy of the COP displacement were computed. A three-way analysis of variance was used to compare groups, genders, and conditions. For standing immediately after performing ten turns, the postural sway parameters were significantly larger in the control group compared to the ballet dancers in both men and women. In this stance condition the values of postural sway and COP velocities in the control group were larger in the men compared to the women. For both genders in the control group all postural sway and COP velocity parameters were larger in standing with eyes closed and standing after performing 10 turns compared to standing with eyes open on both firm and foam surface. In the ballet dancers all COP velocity parameters were larger in standing with eyes closed compared to all other conditions. The results from the present study indicate that professional ballet dancers do not have a better general balance ability than untrained subjects.

Does a Passive Unilateral Lower Limb Exoskeleton Affect Human Static and Dynamic Balance Control?

Exoskeletons are wearable devices closely coupled to the human, which can interact with the musculoskeletal system, e. g., to augment physical and functional capabilities. A main prerequisite for the development and application of exoskeletons is to investigate the human-exoskeleton interaction, particularly in terms of potential inferences with human motor control. Therefore, the purpose of the present study was to investigate whether a passive unilateral lower limb exoskeleton has an impact on static and dynamic reactive balance control. Eleven healthy subjects (22.9 ± 2.5 years, five females) volunteered for this study and performed three different balance tasks: bipedal standing, single-leg standing, and platform perturbations in single-leg standing. All the balance tasks were conducted with and without a passive unilateral lower limb exoskeleton, while force plates and a motion capture system were used to capture the center of pressure mean sway velocity and the time to stabilization, respectively. Dependent t-tests were separately run for both static balance tests, and a repeated-measure analysis of variance with factors exoskeleton and direction of perturbation was calculated for the dynamic reactive balance task. The exoskeleton did not significantly influence postural sway in bipedal stance. However, in single-leg stance, the mediolateral mean sway velocity of the center of pressure was significantly shorter for the exoskeleton condition. For the dynamic reactive balance task, the participants tended to regain stability less quickly with the exoskeleton, as indicated by a large effect size and longer time to stabilization for all directions of perturbation. In summary, the study showed that the exoskeleton provided some assistive support under static conditions, which however may disappear when sufficient stability is available (bipedal stance). Besides, the exoskeleton tended to impair dynamic reactive balance, potentially by impeding adequate compensatory adjustments. These are important findings with strong implications for the future design and application of exoskeletons, emphasizing the significance of taking into account the mechanisms of human motor control.

The specificity versus generality of ball-handling skills - Empirical evidence for a general ball-handling ability

The purpose of this study was to investigate if ball-handling skills are specific and uncorrelated (i.e., motor specificity), or if they share an underlying ball-handling ability (i.e., motor generality). To empirically investigate this question, we had a sample of 201 adolescents perform 12 novel ball-handling tasks. Using confirmatory factor analysis, we showed that a model based on the assumptions of the generality perspective was superior to a model based on assumptions of specificity. The general ball-handling factor did significantly influence the performance on all 12 tasks, with factor loadings ranging between 0.39 and 0.79. The results and it's practical implications are discussed in relation to development of sport specific skills.

Reliability of measures of dynamic stability for the assessment of balance recovery after a forward loss of balance

BACKGROUND

Falls are common and serious events, which mostly occur during locomotion, that are associated with deficient dynamic balance. An experimental approach that simulates falling forward has become increasing popular to investigate dynamic balance. However, research has not been conducted to examine the test-retest reliability of this experimental approach.

RESEARCH QUESTION

What is the reliability of dynamic stability measures that are used for the assessment of balance recovery after forward loss of balance?

METHODS

Nineteen healthy young adults (24.3 ± 2.8 yrs; nine females) volunteered for this study. They reported twice to the laboratory to perform two tests: (i) a stepping task, in which they were instructed to recover balance by taking a step after being suddenly released from an inclined forward position; and (ii) a standing task, in which we aimed to identify the maximum forward leaning angle they were able to compensate for without taking a step. Intra-class correlation coefficients (ICC) were calculated for the margin of stability (MoS) and spatiotemporal parameters for both tests.

RESULTS

The reliability of the stepping task variables ranged from poor to excellent, with ICCs tending to increase with the number of trials included in the analysis. Intra-session analysis (one-way rm ANOVA) revealed a significant trial effect for the MoS, indicating that stepping responses changed across repeated trials. With respect to the standing task, test-retest reliability was only fair for the maximal initial leaning angle.

SIGNIFICANCE

In essence, these results indicate that the inter-session reliability of the stepping task is acceptable, depending on the measures used and the number of trials conducted. However, one must be aware that behavioral adaptations arise with repeated exposure to simulated forward falls. Finally, this study's results suggest that the reproducibility of the standing task is limited.