Neuromotor changes in participants with a concussion history can be detected with a custom smartphone app

Neuromotor dysfunction after a concussion is common, but balance tests used to assess neuromotor dysfunction are typically subjective. Current objective balance tests are either cost- or space-prohibitive, or utilize a static balance protocol, which may mask neuromotor dysfunction due to the simplicity of the task. To address this gap, our team developed an Android-based smartphone app (portable and cost-effective) that uses the sensors in the device (objective) to record movement profiles during a stepping-in-place task (dynamic movement). The purpose of this study was to examine the extent to which our custom smartphone app and protocol could discriminate neuromotor behavior between concussed and non-concussed participants. Data were collected at two university laboratories and two military sites. Participants included civilians and Service Members (N = 216) with and without a clinically diagnosed concussion. Kinematic and variability metrics were derived from a thigh angle time series while the participants completed a series of stepping-in-place tasks in three conditions: eyes open, eyes closed, and head shake. We observed that the standard deviation of the mean maximum angular velocity of the thigh was higher in the participants with a concussion history in the eyes closed and head shake conditions of the stepping-in-place task. Consistent with the optimal movement variability hypothesis, we showed that increased movement variability occurs in participants with a concussion history, for which our smartphone app and protocol were sensitive enough to capture.

Test-Retest reliability and preliminary reliable change estimates for Sway Balance tests administered remotely in community-dwelling adults

OBJECTIVE

Impaired balance and postural stability can occur with advanced age, following traumatic brain injury, in association with neurological disorders and diseases, and as the result of acute or chronic orthopedic problems. The remote assessment of balance and postural stability could be of value in clinical practice and research. We examined the test-retest reliability and reliable change estimates for Sway Balance Mobile Application tests (Sway Medical, Tulsa OK, USA) administered remotely from the participant's home.

METHOD

Primarily young, healthy community-dwelling adults completed Sway Balance Mobile Application tests remotely on their personal mobile devices once per week for three consecutive weeks while being supervised with a video-based virtual connection. Sway Balance tests include five stances (i.e., feet together, tandem right foot forward, tandem left foot forward, single leg right foot, single leg left foot), which are averaged to compute a Sway Balance composite score from 0 to 100, with higher scores indicating better postural stability. We examined test-retest reliability (measured with intraclass correlation coefficients, ICCs) and preliminary reliable change estimates for 70%, 80%, and 90% confidence intervals.

RESULTS

Participants included 55 healthy adults (ages = 26.7 ± 9.9 years, interquartile range = 20-30, range = 18-58; 38 [69%] women). Test-retest reliability for the Sway Balance composite score across three weeks was.88. Test-retest reliability for individual stances ranged from 62 to 83 (all ps < 0.001). At the 80% confidence interval, preliminary reliable changes estimates were 9 points for the Sway Balance composite score.

CONCLUSIONS

For a remote administration, test-retest reliability was moderate-to-good for all Sway Balance stances, as well as for the Sway Balance composite score. Reliable change estimates may allow clinicians to determine whether an improvement or decline in performance is greater than the expected improvement or decline due to measurement error in young adults.

Wearable Devices and Smartphone Inertial Sensors for Static Balance Assessment: A Concurrent Validity Study in Young Adult Population

Falls represent a public health issue around the world and prevention is an important part of the politics of many countries. The standard method of evaluating balance is posturography using a force platform, which has high financial costs. Other instruments, such as portable devices and smartphones, have been evaluated as low-cost alternatives to the screening of balance control. Although smartphones and wearables have different sizes, shapes, and weights, they have been systematically validated for static balance control tasks. Different studies have applied different experimental configurations to validate the inertial measurements obtained by these devices. We aim to evaluate the concurrent validity of a smartphone and a portable device for the evaluation of static balance control in the same group of participants. Twenty-six healthy and young subjects comprised the sample. The validity for static balance control evaluation of built-in accelerometers inside portable smartphone and wearable devices was tested considering force platform recordings as a gold standard for comparisons. A linear correlation (r) between the quantitative variables obtained from the inertial sensors and the force platform was used as an indicator of the concurrent validity. Reliability of the measures was calculated using Intraclass correlation in a subsample (n = 14). Smartphones had 11 out of 12 variables with significant moderate to very high correlation (r > 0.5, p < 0.05) with force platform variables in open eyes, closed eyes, and unipedal conditions, while wearable devices had 8 out of 12 variables with moderate to very high correlation (r > 0.5, p < 0.05) with force platform variables under the same task conditions. Significant reliabilities were found in closed eye conditions for smartphones and wearables. The smartphone and wearable devices had concurrent validity for the static balance evaluation and the smartphone had better validity results than the wearables for the static balance evaluation.

The Relationship Between Human-rated Errors and Tablet-based Postural Sway During the Balance Error Scoring System in Military Cadets

BACKGROUND

The Balance Error Scoring System (BESS) is commonly accepted as a valid measure of postural stability. However, reliability values have varied, and subtle changes undetectable with the human eye may exist postinjury. The inertial measurement unit in commercially available tablets has been used to quantify postural sway (instrumented Balance Error Scoring System [iBESS] volume). However, iBESS has not been validated in a military population, and the stability of the tests beyond 1 week is unknown.

HYPOTHESIS

iBESS volume is capable of objectively measuring postural sway during the traditional BESS.

STUDY DESIGN

Prospective repeated-measures study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Eighty-three cadets (40.96% women; age 20.0 ± 1.44 years; height 68.7 ± 4.1 inches; weight 166.7 ± 30.2 lb) with no history of concussion or lower extremity injury agreed to participate. All participants completed the BESS at baseline and 6 months post baseline. During testing, a tablet equipped with an inertial measurement unit was positioned on the participant's sacrum to capture postural sway.

RESULTS

Moderate to strong correlations were exhibited between baseline measurements for single-limb (SL)-firm (r = 0.84; P < 0.01), tandem (TAN)-firm (r = 0.85; P < 0.01), double-limb (DL)-foam (r = 0.50; P < 0.01), SL-foam (r = 0.59; P < 0.01), and TAN-foam (r = 0.79; P < 0.01). Balance improved significantly at 6 months for SL-firm human-rated errors (Effect Size [ES] = 0.32) and for SL-firm (ES = 0.38), DL-foam (ES = 0.21), and SL-foam iBESS volume (ES = 0.35). Moderate to strong correlations were exhibited between human-rated and iBESS change scores for SL-firm (r = 0.71; P < 0.01), TAN-firm (r = 0.75; P < 0.01), and TAN-foam (r = 0.71; P < 0.01), and a weak correlation was exhibited for DL-foam (r = 0.29; P < 0.01) and SL-foam (r = 0.40; P < 0.01).

CONCLUSION

Moderate to strong correlations existed between human-rated BESS errors and iBESS volume at baseline and between change scores. In addition, iBESS volume may be more sensitive to balance changes than the human-rated BESS.

CLINICAL RELEVANCE

This evidence supports the use of iBESS volume as a valid measure of postural stability in military cadets. iBESS volume may provide clinicians with an objective and more sensitive measure of postural stability than the traditional human-rated BESS.

Development of Data-driven Metrics for Balance Impairment and Fall Risk Assessment in Older Adults

Ageing incurs a natural decline of postural control which has been linked to an increased risk of falling. Accurate balance assessment is important in identifying postural instability and informing targeted interventions to prevent falls in older adults. Inertial sensor (IMU) technology offers a low-cost means for objective quantification of human movement. This paper describes two studies carried out to advance the use of IMU-based balance assessments in older adults. Study 1 (N=39) presents the development of two new IMU-derived balance measures. Study 2 (N=248) reports a reliability analysis of IMU postural stability measures and validates the novel balance measures through comparison with clinical scales. We also report a statistical fall risk estimation algorithm based on IMU data captured during static balance assessments alongside a method of improving this fall risk estimate by incorporating standard clinical fall risk factor data. Results suggest that both new balance measures are sensitive to balance deficits captured by the Berg Balance Scale (BBS) and Timed Up and Go test. Results obtained from the fall risk classifier models suggest they are more accurate (67.9%) at estimating fall risk status than a model based on BBS (59.2%). While the accuracies of the reported models are lower than others reported in the literature, the simplicity of the assessment makes it a potentially useful screening tool for balance impairments and falls risk. The algorithms presented in this paper may be suitable for implementation on a smartphone and could facilitate unsupervised assessment in the home.

Test-Retest Reliability and Reliable Change Estimates for Four Mobile Cognitive Tests Administered Virtually in Community-Dwelling Adults

Objective: Remote mobile cognitive testing (MCT) is an expanding area of research, but psychometric data supporting these measures are limited. We provide preliminary data on test-retest reliability and reliable change estimates in four MCTs from SWAY Medical, Inc. Methods: Fifty-five adults from the U.S. Midwest completed the MCTs remotely on their personal mobile devices once per week for 3 consecutive weeks, while being supervised with a video-based virtual connection. The cognitive assessment measured simple reaction time ("Reaction Time"), go/no-go response inhibition ("Impulse Control"), timed visual processing ("Inspection Time"), and working memory ("Working Memory"). For each cognitive test except Working Memory, we analyzed both millisecond (ms) responses and an overall SWAY composite score. Results: The mean age of the sample was 26.69years (SD=9.89; range=18-58). Of the 55 adults, 38 (69.1%) were women and 49 (89.1%) used an iPhone. Friedman's ANOVAs examining differences across testing sessions were nonsignificant (ps>0.31). Intraclass correlations for Weeks 1-3 were: Reaction Time (ms): 0.83, Reaction Time (SWAY): 0.83, Impulse Control (ms): 0.68, Impulse Control (SWAY): 0.80, Inspection Time (ms): 0.75, Inspection Time (SWAY): 0.75, and Working Memory (SWAY): 0.88. Intraclass correlations for Weeks 1-2 were: Reaction Time (ms): 0.75, Reaction Time (SWAY): 0.74, Impulse Control (ms): 0.60, Impulse Control (SWAY): 0.76, Inspection Time (ms): 0.79, Inspection Time (SWAY): 0.79, and Working Memory (SWAY): 0.83. Natural distributions of difference scores were calculated and reliable change estimates are presented for 70, 80, and 90% CIs. Conclusion: Test-retest reliability was adequate or better for the MCTs in this virtual remote testing study. Reliable change estimates allow for the determination of whether a particular level of improvement or decline in performance is within the range of probable measurement error. Additional reliability and validity data are needed in other age groups.

Normative Data for the Sway Balance System

OBJECTIVE

Static balance, postural stability, and reaction time are commonly impaired after a sport-related concussion. The Sway Balance System assesses postural sway (ie, stability) and simple reaction time using the triaxial accelerometer built into iOS mobile devices. The purpose of this study was to provide normative data for children and adolescents and to examine for age and sex differences on the Sway Balance System.

DESIGN

Cross-sectional study.

SETTING

Middle and high schools across the United States.

PARTICIPANTS

Participants were 3763 youth aged 9 to 21 years who completed the Sway Balance System Sports protocol in accordance with the company's recommended methods (ie, 1 acclimation trial and 2-3 baseline tests).

INDEPENDENT VARIABLES

Age and sex.

MAIN OUTCOME MEASURES

Sway Balance score (0-100) and Sway Reaction Time score (0-100).

STATISTICAL ANALYSIS

A multivariate analysis of variance examined the effects of age and sex on balance and reaction time scores.

RESULTS

Sway Balance and Reaction Time scores significantly differed by age [F(10, 7494) = 39.68, P < 0.001, V = 0.10, = 0.05] and sex [F(4, 7494) = 55.29, P < 0.001, V = 0.06, = 0.03]. Post hoc analyses revealed that older groups generally had better scores than younger groups on all balance comparisons (ps < 0.001) and many reaction time comparisons. Girls performed better than boys on balance [F(2, 3747) = 53.79, P < 0.001, = 0.03] and boys had faster reaction times [F(2, 3747) = 37.11, P < 0.001, = 0.02].

CONCLUSIONS

Age and sex are important factors to consider when assessing Balance and Reaction Time scores using the Sway Balance System's Sports protocol in youth. We provide age- and sex-based normative values for the Sway Balance System, which will likely be helpful when using this technology to assess and manage concussions.

Sway Balance Mobile Application: Reliability, Acclimation, and Baseline Administration

OBJECTIVES

To describe historic baseline session administration practices, to assess the utility of a practice trial (an acclimation trial) before the official balance session, and to examine the within-session reliability of the Sway Balance Mobile Application (SBMA).

DESIGN

Retrospective observational study.

SETTING

Middle schools, high schools, and colleges across the United States.

PARTICIPANTS

More than 17 000 student-athletes were included in the Sway Medical database with 7968 individuals meeting this study's inclusion criteria.

INDEPENDENT VARIABLES

The Sway Medical database included the following subject characteristics for each student-athlete: age, sex, weight, and height.

MAIN OUTCOME MEASURES

Balance assessment score generated by the SBMA.

RESULTS

Variable administration practices with significant differences between baseline session averages across methods were found. Individuals who performed an acclimation trial had a significantly higher baseline session average than those who did not. Within-session reliability estimates were in the low to adequate range (r = 0.53-0.78), with higher estimates found for 2 consecutive baseline tests (r = 0.75-0.78).

CONCLUSIONS

For maximum clinical utility, a standardized protocol for postural control baseline acquisition is necessary. Acclimation trial should be administered before a baseline session to minimize variability, especially with only 1 to 2 baseline tests. The highest reliability was observed across 2 consecutive baseline tests within the same baseline session. We suggest obtaining baseline balance measurements with an acclimation trial followed by a baseline session with 2 baseline tests. Prospective studies are required for validation.

Reliability, Validity and Utility of Inertial Sensor Systems for Postural Control Assessment in Sport Science and Medicine Applications: A Systematic Review

BACKGROUND

Recent advances in mobile sensing and computing technology have provided a means to objectively and unobtrusively quantify postural control. This has resulted in the rapid development and evaluation of a series of wearable inertial sensor-based assessments. However, the validity, reliability and clinical utility of such systems is not fully understood.

OBJECTIVES

This systematic review aims to synthesise and evaluate studies that have investigated the ability of wearable inertial sensor systems to validly and reliably quantify postural control performance in sports science and medicine applications.

METHODS

A systematic search strategy utilising the PRISMA guidelines was employed to identify eligible articles through ScienceDirect, Embase and PubMed databases. In total, 47 articles met the inclusion criteria and were evaluated and qualitatively synthesised under two main headings: measurement validity and measurement reliability. Furthermore, studies that investigated the utility of these systems in clinical populations were summarised and discussed.

RESULTS

After duplicate removal, 4374 articles were identified with the search strategy, with 47 papers included in the final review. In total, 28 studies investigated validity in healthy populations, and 15 studies investigated validity in clinical populations; 13 investigated the measurement reliability of these sensor-based systems.

CONCLUSIONS

The application of wearable inertial sensors for sports science and medicine postural control applications is an evolving field. To date, research has primarily focused on evaluating the validity and reliability of a heterogeneous set of assessment protocols, in a laboratory environment. While researchers have begun to investigate their utility in clinical use cases such as concussion and musculoskeletal injury, most studies have leveraged small sample sizes, are of low quality and use a variety of descriptive variables, assessment protocols and sensor-mounting locations. Future research should evaluate the clinical utility of these systems in large high-quality prospective cohort studies to establish the role they may play in injury risk identification, diagnosis and management. This systematic review was registered with the International Prospective Register of Systematic Reviews on 10 August 2018 (PROSPERO registration: CRD42018106363): https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=106363 .

Use of Wearable Sensor Technology in Gait, Balance, and Range of Motion Analysis

More than 8.6 million people suffer from neurological disorders that affect their gait and balance. Physical therapists provide interventions to improve patient’s functional outcomes, yet balance and gait are often evaluated in a subjective and observational manner. The use of quantitative methods allows for assessment and tracking of patient progress during and after rehabilitation or for early diagnosis of movement disorders. This paper surveys the state-of-the-art in wearable sensor technology in gait, balance, and range of motion research. It serves as a point of reference for future research, describing current solutions and challenges in the field. A two-level taxonomy of rehabilitation assessment is introduced with evaluation metrics and common algorithms utilized in wearable sensor systems.

Normative Data Set of SWAY Balance Mobile Assessment in Pediatric Athletes

OBJECTIVE

To examine and describe normative values for an objective, mobile measure of postural stability commonly used in concussion assessments, SWAY Balance (SWAY Medical, Tulsa, Oklahoma).

DESIGN

Retrospective analysis of baseline balance assessments in a healthy pediatric population.

SETTING

Baseline assessments completed by certified athletic trainers at an outpatient concussion center or sports medicine offices in Philadelphia, PA and surrounding suburban Pennsylvania and New Jersey or during an athletic trainer's baseline assessment of collegiate athletes at a National Collegiate Athletic Association (NCAA) Division-II University in Fort Lauderdale, FL.

PARTICIPANTS

Test results of a sample of 466 athletes aged 5 to 18 years were included.

INTERVENTIONS

The SWAY Balance test was administered using a mobile device on all participants as part of a standard preseason, baseline evaluation, following the standard evaluation protocol.

MAIN OUTCOME MEASURES

Baseline SWAY Balance mobile assessment balance and reaction time scores, age and sex effects, were examined.

RESULTS

Normative scores are described, with results stratified into 4 age groups (5-9, 10-12, 13-17, and 18 years old). Balance scores, overall and within each individual stance score, improved with the age of the participants. Sex effects on balance were only seen in single-leg stances, with females outperforming males. Reaction time was found to be faster in males and improved with age, peaking at 13 to 17 years old and slowing in 18-year-olds.

CONCLUSIONS

Normative, age-specific SWAY Balance test results provided are of clinical use as references in the concussion assessments of pediatric athletes.

Can We Rely on Mobile Devices and Other Gadgets to Assess the Postural Balance of Healthy Individuals? A Systematic Review

The consequences of falls, costs, and complexity of conventional evaluation protocols have motivated researchers to develop more effective balance assessments tools. Healthcare practitioners are incorporating the use of mobile phones and other gadgets (smartphones and tablets) to enhance accessibility in balance evaluations with reasonable sensitivity and good cost–benefit. The prospects are evident, as well as the need to identify weakness and highlight the strengths of the different approaches. In order to verify if mobile devices and other gadgets are able to assess balance, four electronic databases were searched from their inception to February 2019. Studies reporting the use of inertial sensors on mobile and other gadgets to assess balance in healthy adults, compared to other evaluation methods were included. The quality of the nine studies selected was assessed and the current protocols often used were summarized. Most studies did not provide enough information about their assessment protocols, limiting the reproducibility and the reliability of the results. Data gathered from the studies did not allow us to conclude if mobile devices and other gadgets have discriminatory power (accuracy) to assess postural balance. Although the approach is promising, the overall quality of the available studies is low to moderate.

Senior Sway: Using a Mobile Application to Measure Fall Risk

BACKGROUND AND PURPOSE

The Senior Sway mobile application uses the iPhone/iPad gyroscope to assess postural sway and motion reaction time. Impairment in postural sway and motion reaction time have the potential to increase risk for future falls. Senior Sway thereby has the potential to provide a quick, easy to use, objective measure for predicting falls in older adults. The purpose of this study was to evaluate the feasibility of the Senior Sway mobile application and its associations with fall risk in community-dwelling older adults.

METHODS

Adults older than 62 years were recruited from senior centers and community events. Descriptive and bivariate statistics were used to examine feasibility on the basis of enrollment, time required, satisfaction with application, and association with fall risk.

RESULTS AND DISCUSSION

Fifty-seven adults were recruited. Use of the Senior Sway mobile application was feasible. Ninety-one percent said that they liked the application and reported length of time of assessment was "just right." The average Senior Sway score was 64.0 (range: 47.8-84.0), which was significantly associated with the 30-second sit-to-stand test. In addition, the motor reaction time score was associated with the Timed Up and Go.

CONCLUSIONS

Senior Sway is a promising application to improve identification of adults at risk for falls and need for rehabilitation but warrants further research.

Level of Agreement Between Human-Rated and Instrumented Balance Error Scoring System Scores

Clinicians have used the Balance Error Scoring System (BESS) to quantify postural control for concussion management. However, the reliability of the human rated BESS has varied prompting the development of instrumented BESSs. A cross-sectional design was used to determine the level of agreement (LOA) between human rated and instrumented BESS scores. Sixty participants completed the BESS on video. An instrumented mat was used to quantify BESS errors while a live human rater simultaneously scored the BESS. A second human rated BESS performance via video. Bland-Altman LOA analyses evaluated agreement between scoring methods (Mat-Human, Mat-Video, Video-Live) for each stance. Mean biases between scores, for each stance, with 95% confidence intervals (95%CIs) were calculated. Agreement between scoring methods was not assessed for the Firm-Double-Limb stance because very few errors were recorded. Agreement between both human raters and the mat was poor based on mean bias estimates > ± 1 and/or wide 95%CIs for all stances including BESS-Total. Agreement between the human raters was better, having displayed consistently smaller mean bias estimates and tighter 95%CIs for all stances and BESS Total. As a result, human rated and instrumented BESS scores may not be comparable. One method should be used to measure BESS errors for consistency.

Reliability and validity of the Sway Balance mobile application for measurement of postural sway in people with Parkinson disease

BACKGROUND

The emergence of mobile technology allows the examination of balance through direct measures of postural sway in a cost-effective, convenient and portable fashion. However, there is insufficient evidence for use in populations with neurologic conditions.

OBJECTIVES

1) To determine the test-retest reliability of the Sway Balance™ mobile application in measuring postural sway in individuals with Parkinson disease, 2) To examine the concurrent validity of Sway Balance™ with inertial measurement units and 3) To determine if Sway Balance™ scores can predict disease severity.

METHODS

Thirty subjects with early stage idiopathic Parkinson disease completed three trials of two Sway Balance™ protocols while postural sway was simultaneously measured by two inertial measurement units and Sway Balance™, then repeated testing one week later.

RESULTS

Sway Balance demonstrated high test-retest reliability for both protocols (ICC = 0.72 and 0.92) and good to excellent inverse correlation with the inertial measurement units across both protocols (ρ= -0.61- -0.92; p < 0.001). Sway Balance™ did not accurately predict disease severity.

CONCLUSION

Sway Balance™ demonstrates strong test-retest reliability and concurrent validity with measures from inertial measurement units. Questions remain regarding the ability of Sway Balance™ to accurately characterize balance of individuals who demonstrate difficulty maintaining the test condition.

A Critical Review of Consumer Wearables, Mobile Applications, and Equipment for Providing Biofeedback, Monitoring Stress, and Sleep in Physically Active Populations

The commercial market for technologies to monitor and improve personal health and sports performance is ever expanding. A wide range of smart watches, bands, garments, and patches with embedded sensors, small portable devices and mobile applications now exist to record and provide users with feedback on many different physical performance variables. These variables include cardiorespiratory function, movement patterns, sweat analysis, tissue oxygenation, sleep, emotional state, and changes in cognitive function following concussion. In this review, we have summarized the features and evaluated the characteristics of a cross-section of technologies for health and sports performance according to what the technology is claimed to do, whether it has been validated and is reliable, and if it is suitable for general consumer use. Consumers who are choosing new technology should consider whether it (1) produces desirable (or non-desirable) outcomes, (2) has been developed based on real-world need, and (3) has been tested and proven effective in applied studies in different settings. Among the technologies included in this review, more than half have not been validated through independent research. Only 5% of the technologies have been formally validated. Around 10% of technologies have been developed for and used in research. The value of such technologies for consumer use is debatable, however, because they may require extra time to set up and interpret the data they produce. Looking to the future, the rapidly expanding market of health and sports performance technology has much to offer consumers. To create a competitive advantage, companies producing health and performance technologies should consult with consumers to identify real-world need, and invest in research to prove the effectiveness of their products. To get the best value, consumers should carefully select such products, not only based on their personal needs, but also according to the strength of supporting evidence and effectiveness of the products.

Smartphone Applications to Perform Body Balance Assessment: a Standardized Review

Body balance disorders are related to different injuries that contribute to a wide range of healthcare issues. The social and financial costs of these conditions are high. Therefore, quick and reliable body balance assessment can contribute to the prevention of injuries, as well as enhancement of clinical rehabilitation. Moreover, the use of smartphone applications is increasing rapidly since they incorporate different hardware components that allow for body balance assessment. The present study aims to show an analysis of the current applications available on Google Play Store^TM and iTunes App Store^TM to measure this physical condition, using the Mobile Application Rating Scale (MARS). Three iOS and two Android applications met the inclusion criteria. Three applications have scientific support, Balance test YMED, Balance Test by Slani, and Sway. Furthermore, according to MARS, the main scores for each evaluated domain were: Engagement (2.04), Functionality (3.8), Esthetics (3.53), and Information (3.80). The reviewed applications targeted to assess body balance obtained good mean scores. Sway is the app with highest scores in each MARS domain, followed by iBalance Fitness and Gyrobalance.