Intersession Reliability Research Articles

Validation of a 3D Markerless Motion Capture Tool Using Multiple Pose and Depth Estimations for Quantitative Gait Analysis

Gait analysis is essential for evaluating walking patterns and identifying functional limitations. Traditional marker-based motion capture tools are costly, time-consuming, and require skilled operators. This study evaluated a 3D Marker-less Motion Capture (3D MMC) system using pose and depth estimations with the gold-standard Motion Capture (MOCAP) system for measuring hip and knee joint angles during gait at three speeds (0.7, 1.0, 1.3 m/s). Fifteen healthy participants performed gait tasks which were captured by both systems. The 3D MMC system demonstrated good accuracy (LCC > 0.96) and excellent inter-session reliability (RMSE < 3°). However, moderate-to-high accuracy with constant biases was observed during specific gait events, due to differences in sample rates and kinematic methods. Limitations include the use of only healthy participants and limited key points in the pose estimation model. The 3D MMC system shows potential as a reliable tool for gait analysis, offering enhanced usability for clinical and research applications.

Validity and reliability of trunk and lower-limb kinematics during squatting, hopping, jumping and side-stepping using OpenCap markerless motion capture application

ABSTRACT OpenCap is a web-based markerless motion capture platform that estimates 3D kinematics from videos recorded from at least two iOS devices. This study aimed to determine the concurrent validity and inter-session reliability of OpenCap for measuring trunk and lower-limb kinematics during squatting, hopping, countermovement jumping, and cutting. Nineteen participants (10 males, 9 females; age 27.7 ± 4.1 years) were included. Countermovement jump, single-leg triple vertical hop, single-leg squat, sidestep cutting and side hop tasks were assessed. For validity, OpenCap was compared to a marker-based motion capture system using root-mean-square error. Test–retest reliability of OpenCap was determined using intraclass correlations and minimum detectable change (MDC) from two testing sessions. The squat had the lowest RMSE across joint angles (mean = 7.0°, range = 2.9° to 13.6°). For peak angles, the countermovement jump (jump phase) (ICC = 0.62–0.93) and the squat (ICC = 0.60–0.92) had the best reliability across all joints. For initial contact, the side hop had the best inter-session reliability (ICC = 0.70–0.94) across all joint angles. As such, OpenCap validity and reliability are joint and task specific.

Intra- and inter-session reliability of air plethysmography for assessing body composition in university athletes

Intra- and inter-session reliability of air plethysmography for assessing body composition in university athletes

Assessment of autostereoscopic perception using artificial intelligence-enhanced face tracking technology.

Stereopsis, the ability of humans to perceive depth through distinct visual stimuli in each eye, is foundational to autostereoscopic technology in computing. However, ensuring stable head position during assessments has been challenging. This study evaluated the utility of artificial intelligence (AI)-enhanced face tracking technology in overcoming this challenge by ensuring that each eye consistently receives its intended image. The Lume Pad 2, an autostereoscopic tablet with AI-enhanced face tracking, was utilized to simulate quantitative parts of the Stereo Fly test and TNO Stereotests for contour and random dot stereopsis. The study recruited 30 children (14 males and 16 females, mean age of 9.2 ± 0.3 years, age range of 6-12 years) and 30 adults (10 males and 20 females, mean age of 29.4 ± 1.0 years, age range of 21-42 years) to assess the tablet's inter-session reliability. Agreement between conventional and the autostereoscopic tablet-simulated stereotests was tested in a larger group of 181 children (91 males and 90 females, mean age of 9.1 ± 0.4 years, age range of 6-12 years) and 160 adults (69 males and 91 females, mean age of 38.6 ± 2.1 years, age range of 21-65 years). Inter-session reliability and agreement were analyzed using weighted Kappa coefficient and non-parametric Bland-Altman analysis. The autostereoscopic tablet demonstrated high inter-session reliability (κ all > 0.80), except for the simulated TNO Stereotest in adults, which demonstrated moderate inter-session reliability (κ = 0.571). Non-parametric Bland-Altman analysis revealed zero median differences, confirming consistent inter-session reliability. Similar patterns were observed in comparing AI-based and conventional methods, with both the weighted Kappa coefficient (κ all > 0.80) and non-parametric Bland-Altman analysis indicating significant agreement. The agreement between methodologies was confirmed by permissible differences, which were smaller than the minimum step range. The integration of AI-based autostereoscopic technology with sub-pixel precision demonstrates significant potential for clinical stereopsis measurements.

Evaluating the reproducibility and validity of maximal mouth opening measurement techniques

ObjectivesA limitation of the maximal mouth opening (MMO) is a frequent complication of oral (cancer) surgery. The measurement between the right central incisors is considered the golden standard for assessing MMO, although it has been noted to overestimate MMO in edentulous patients. This study aims to evaluate the reproducibility and validity of four MMO techniques and to determine the extent to which they are dependent on the remaining dentition. Materials and MethodsFour methods for capturing the MMO were recorded in consecutive patients with mixed dentition. The degree of agreement between the different measurement methods was compared using Bland-Altman plots. To investigate the reproducibility of each method, intersession, interobserver and intraobserver reliability were calculated for measurements performed by two clinicians across two sessions. Two subgroups were created based on dentition: (A) cases missing at least one right central incisor, and (B) patients with both right central incisors present. ResultsAll but one intraclass correlation coefficient (ICC) demonstrated excellent reproducibility (ICC > 0.9). The highest ICC values were found for the intraoral MMO(iMMO) and corrected intraoral MMO(ciMMO) method. A significant relationship between the MMO in both subgroups was identified only for the intraoral Range of Motion (iROM) method (p=.010*). ConclusionThe findings suggest that the current golden standard for measuring MMO does not adequately account for the absence of the right central incisor(s). Two of the proposed methods, which include corrections for missing incisors, should be incorporated into future clinical trials on MMO.

Intra- and inter-session reliability of countermovement jump and gait analysis in collegiate athletes measured using an inertial measurement unit (BTS G-Walk)

This study assessed the intra- and inter-session reliability of the inertial measurement unit (IMU) in measuring countermovement jump (CMJ) and 10m-walking gait-related outcomes. Thirty collegiate-level athletes (15 males [age: 21.0 ± 2.5 years] and 15 females [age: 21.5 ± 2.1 years]) were recruited to perform CMJs and 10m-walking test that were simultaneously recorded using the commercially available body-worn IMU – BTS G-walk. The coefficient of variation (CV), the analysis of variance with repeated measures (ANOVA), and the interclass correlation coefficient (ICC) were used for intra-session reliability. While the Pearson’s correlation coefficient (r) and the ICC were used to analyze inter-session reliability. Measurement of CMJ and 10m-walking test gait variables using the IMU resulted in moderate to excellent intra-session reliability for CMJ (ICC = 0.881 to 0.988) and gait analysis (ICC = 0.807 to 0.978) with acceptable CV (≤10%). Inter-session reliability for CMJ variables ranged from poor to excellent (ICC = 0.134 to 0.963), and 10-m walking test gait analysis variables were moderate to excellent (ICC = 0.683 to 0.931). The IMU (BTS G-walk) provides reliable data for most CMJ and gait variables. Future studies may determine the accuracy of the equipment to monitor changes over time (e.g., after a training intervention).

A Specific Test of Starting Blocks: Intrasession and Intersession Reliability of Isometric Strength Using a Functional Electromechanical Dynamometer

Aims: To determine the intrasession and intersession reliability of the isometric force at three different starting block positions, to compare the intrasession and intersession reliability of the peak and average isometric force of three different starting block positions, and to compare the intrasession and intersession reliability of three different starting block positions. Methods: Eighteen male college students participated in this study. A repeated measures design was used to evaluate the intrasession and intersession reliability of isometric force in three different starting block positions. Results: Very high and extremely high reliability of the average and peak isometric force of the three positions of the starting blocks were obtained, with ICC ranging from 0.63 to 0.91 and a CV close to 10%. Peak force was able to determine the outcomes of the bilateral position with higher reliability than the mean force, and the dominant was the most reliable position for assessing the starting blocks. Conclusion: The functional electromechanical dynamometer can be used with a high level of reliability to assess the force exerted in the starting blocks.

The Test-Retest Reliability of Pain Outcome Measures in People With Phantom Limb Pain.

To quantify the test-retest reliability of 3 patient-reported outcome measures of pain for people living with phantom limb pain (PLP) and assess the impact of test-retest errors on future research and clinical decisions. Thirty-nine participants (30 males), mean (SD) age: 55 (16), mean (SD) years postamputation: 6.8 (8.3), reported their PLP levels on a visual analogue scale (VAS) for pain intensity, the revised short-form McGill Pain Questionnaire (SF-MPQ-2), and a pain diary, on 2 occasions 7 to 14 days apart. Mean systematic change, within-subjects SD, limits of agreement (LOA), coefficient of variation, and the intraclass correlation coefficient (ICC) were quantified alongside their respective 95% confidence intervals (95% CIs). Systematic learning effects (mean changes) were not clinically relevant across the VAS, SF-MPQ-2, and pain diary. Within-subject SDs (95% CI) were 11.8 (9.6-15.3), 0.9 (0.7-1.2), and 8.6 (6.9-11.5), respectively. LOA (95% CI) were 32.6 (26.5-42.4), 2.5 (2-3.3), and 23.9 (19.2-31.8), respectively. ICCs (95% CI) were 0.8 (0.6-0.9), 0.8 (0.7-0.9), and 0.9 (0.8-0.9), respectively, but may have been inflated by sample heterogeneity. The test-retest errors allowed detection of clinically relevant effect sizes with feasible sample sizes in future studies, but individual errors were large. For people with PLP, a pain intensity VAS, the SF-MPQ-2, and a pain diary show an acceptable level of intersession reliability for use in future clinical trials with feasible sample sizes. Nevertheless, the random error observed for all 3 of the pain outcome measures suggests they should be interpreted with caution in case studies and when monitoring individuals' clinical status and progress.

The Reliability of Field-Based Static and Dynamic Balance Tests in Primary School-Aged Autistic Children.

Previous research has proven that the balance of autistic children is poor. However, the reliability of assessing balance in this cohort has been inadequately researched. This study therefore aimed to examine if field-based static and dynamic balance tests can be reliably assessed in autistic children, to determine the number of familiarisation sessions required and whether autistic severity impacts on the reliability of these balance tests. The balance of eighteen primary school-aged autistic children was assessed three times a week over five weeks, using the flamingo balance test, a modified version of the balance error scoring system (BESS), the low beam walking test, and the heel to toe walking test. Reliability criteria included an intraclass correlation coefficient (ICC) level of ≥0.75 and a coefficient of variance (CV%) of ≤46% for the low beam walking test, the heel to toe walking test, and the BESS, and a CV% of ≤82% or the flamingo balance test. Inter-session reliability was achieved and required the least number of familiarisation sessions for the flamingo balance test, compared to the low beam walking test, which required a greater number of familiarisation sessions to achieve inter-session reliability. The heel to toe walking test and the BESS achieved inter-session reliability and familiarisation in an acceptable time frame. Due to the large CV% values reported in the current study, practitioners need to be aware that balance interventions need to achieve improvements greater than the CV% in this cohort.

Intersession reliability of center of pressure measurement during bipedal standing with different count-back orders

IntroductionDual-task assessments can identify changes in postural control during balance assessments. Static standing with backward counting is frequently used to evaluate postural control while dual-tasking. The most reliable countdown method for standing postural stability has not yet been defined. Research objectiveto investigate postural stability's intra- and inter-day reliability while backward counting in different steps. MethodThirty-nine healthy adults (20 females, 26.94 ± 7.55 years) completed 70 s trials of stability tests with no dual-task, counting backward under five conditions (in ones, tows, threes, fours, and fives) while standing on a force-plate in three sessions: two sessions were on the same day, and the third session was one-week apart. The repeatability of measurements was tested using repeated-measure analysis of variance, interclass correlation, and standard error of measurements. ResultsThe interclass correlation scores ranged from 0.67 to 0.92, and the standard error of measurements ranged from 2.9% to 13.4%. No significant systematic changes (p < 0.05) occurred between the testing sessions for any backward counting. DiscussionThe backward counting showed higher reliability when performed in condition 5 (counting backward in five's). The inter-day reliability scores were greater than intera-day reliability. ConclusionsDual-tasking with most backward counting (in ones to fives) is reliable, and a quantitative assessment of the center of pressure could be used to monitor the changes in postural stability between sessions.

Pole Dancing-Specific Muscle Strength: Development and Reliability of a Novel Assessment Protocol.

Pole dancing is a physically demanding sport that combines dance and acrobatic movements on a vertical pole. Despite its highly growing popularity, there is currently limited research in the field. The aim of this study was to create and evaluate a strength assessment protocol for athletes in pole dancing, with a specific focus on functional positions on the pole. Thirty-two female pole dancing athletes participated in this study. Maximal voluntary isometric contractions (MVIC) were measured at three different sport-specific positions on the pole (shoulder abduction and adduction, and hip adduction), on two separate days (test and re-test) with a five to seven day interval between them. A hand-held dynamometer (Activ5- Activbody) stabilized on the pole was used for this study. The intra-session reliability was good to excellent for all sports-specific positions and for both sides of the body, across all different movements (ICC = 0.837-0.960, SEM = 5.02Kg-2.24Kg, and SDD = 27.46%-14.92%). Slightly better results were found regarding inter-session reliability (ICC = 0.927-0.970, SEM = 3.72Kg-1.97Kg, and SDD = 22.86%-15.19%). There was not a statistically significant difference between the MVICs between the left and right or dominant and non-dominant side in shoulder abduction (p = 0.105) and hip adduction (p = 0.282), in contrast to shoulder adduction (p = 0.00). The strength assessment protocol developed in the current study has proven to be a reliable and functional tool, with the potential for utilization in clinical practice as part of objective strength testing. Further studies are needed in order to expand the protocol to other muscle groups and positions and to generalize the results in all pole dancing populations such as male athletes.

COMPARISON OF INTER-SESSION, INTRA-RATER AND INTER-RATER RELIABILITY OF SINGLE AND DOUBLE LEG LANDING ERROR SCORING SYSTEM USING DIFFERENT CALCULATION METHODS

INTRODUCTION &amp; AIMS The Landing Error Scoring System (LESS) is used for screening noncontact anterior cruciate ligament (ACL) injury risk. The LESS is deemed a valid and reliable indicator of landing biomechanics that predict noncontact ACL injuries. We have sought to validate a Single-Leg Landing Error Scoring System (SLESS) against the established LESS. There are seven distinct calculation methods for final LESS scores, adding variability to the original version and the risk of misinterpreting results. This study used different calculation methods to investigate the inter-session, intra-rater and inter-rater reliability of the SLESS and LESS scores. METHODS Thirty-five team sports players performed four drop jump landing variations (dominant leg, non-dominant leg, double-leg and cognitive loading drill with double-leg) over three sessions. Sessions 1 and 2 were conducted on the same day, with Session 3 a week later. Video footage from frontal and sagittal views captured all landings. Three professionals scored recorded trials using standard SLESS and LESS protocols. One scorer assessed intra-session and inter-session reliability, while three evaluated inter-rater reliability. The final SLESS and LESS scores were calculated using original version/OG, average of 3 trials-AV, worst trial/WT, best score/BS, first trial/FT, last trial/LT, error present in at least two of three trials/TT). Reliability was assessed using intraclass correlation coefficient (ICC), standard error of measurement (SEM), and coefficient of variation (CV) with 95% confidence intervals. RESULTS The study observed acceptable inter-session reliability across single-leg and double-leg drop jump landing tasks using all seven calculation methods (SLESS: ICC=0.80-0.91, SEM=1.07-1.10, CV=6.5-10.1%; LESS: ICC=0.63-0.90, SEM=1.06-1.11, CV=5.7-11.5%). The study also demonstrated acceptable intra-rater reliability for all tasks using all calculation methods (SLESS: ICC=0.86-0.94, SEM=1.05-1.08, CV=5.0-8.5%; LESS: ICC=0.74-0.93, SEM=1.04-1.08, CV=4.2-8.5%). In addition, acceptable inter-rater reliability was shown for all tasks using all calculation methods (SLESS: ICC=0.69-0.83, SEM=1.11-1.18, CV=10.5-18.0%; LESS: ICC=0.54-0.82, SEM=1.10-1.20, CV=10.3-20.3%). CONCLUSION The study indicates the reliability of all seven calculation methods for SLESS and LESS scores. Precise specification of the chosen calculation method is crucial for practitioners and researchers.

Assessing Jump Performance: Intra- and Interday Reliability and Minimum Difference of Countermovement Jump and Drop Jump Outcomes, Kinetics, Kinematics, and Jump Strategy

Understanding the reliability of jump testing is essential to determine the neuromuscular progress of athletes and make informed decisions. This study aimed to assess the reliability of several countermovement jump (CMJ) and drop jump (DJ) test metrics in female volleyball players. Sixteen (n = 16) semi-professional female volleyball players participated in this test-retest study. Intrasession and intersession reliability of CMJ and DJ metrics were evaluated using a randomized cross-over design. A dual force platform was used to collect CMJ and DJ data, and several dependent variables were calculated using forward dynamics. Intraclass correlation coefficients (ICC), coefficients of variation (CV), and minimum difference (MD) were calculated to assess intra- and interday reliability. During the same testing, the third attempt consistently yielded the highest values for both tests in jump height but presented excellent reliability (CMJ: ICC [95%CI] = 0.97 [0.93–0.99]; CV [95%CI] = 4.1% [1.2–7.0]; MD95 = 3.5 cm; MD90 = 2.9 cm; DJ: ICC [95%CI] = 0.91 [0.77–0.97]; CV [95%CI] = 6.7% [1.9–11.5]; MD95 = 6.0 cm; MD90 = 5.0 cm). CMJ height exhibited excellent reliability between sessions (ICC [95%CI] = 0.93 [0.81–0.97]; CV [95%CI] = 3.8% [1.1–6.4]; MD95 = 3.5 cm; MD90 = 3.0 cm), whereas DJ height demonstrated slightly lower but still acceptable intersession reliability (ICC [95%CI] = 0.81 [0.55–0.93]; CV [95%CI] = 6.1% [1.7–10.4]; MD95 = 5.2 cm; MD90 = 4.4 cm). Intersession reliability for CMJ kinetics and kinematics was excellent for 13 of the 24 metrics assessed. For DJ, only concentric (ICC [95%CI] = 0.91 [0.76–0.97]; CV [95%CI] = 3.0% [0.9–5.2]; MD95 = 15 Ns; MD90 = 12.6 Ns) and eccentric impulses (ICC [95%CI] = 0.99 [0.96–0.99]; CV [95%CI] = 1.7% [0.5–2.9]; MD95 = 9.2 Ns; MD90 = 7.7 Ns) demonstrated excellent intersession reliability. Most CMJ variables showed excellent reliability within sessions, while DJ had lower reliability in most metrics. These findings provide valuable information to physical trainers to select the metrics to assess athletes’ performance as well as to identify a minimum cut-off value that serves as a reference for each of the metrics reported in both tests.

Intersession reliability of center of pressure measurement during bipedal standing with different foot placement angles

IntroductionThe foot placement is a determinant of the base of support and influences standing balance. The reliability of postural stability tests with different foot placement angles is unclear. Research questionTo determine and compare the intra- and inter-day reliability of the center of pressure-based postural stability while standing with different foot placement angles. MethodTwenty-five healthy adults (16 females and 9 males; age: 29 ± 6 years) completed 70 s trials of eyes open and eyes closed stability tests with 0°, 15°, 30°, and 45° angles between the feet while standing on a forceplate in three sessions: two sessions were in the same day, and the third session was one-week apart. The repeatability of measurements was tested using analysis of variance, interclass correlation, and standard error of measurements. ResultThroughout the three study sessions, there was no difference in postural stability while participants stood with different foot placement angles. The interclass correlation scores ranged from 0.71 to 0.96, the standard error of measurements ranged from 2.1% to 12.9%, and no significant systematic changes (p < 0.05) occurred between the testing sessions for any foot placements. Standing with a 45° angle between the feet with closed eyes showed higher reliability values than other conditions. The intra-day reliability scores were greater than inter-day reliability. DiscussionThe relative reliability of postural stability could be impacted by foot placement angles, which might alter ankle mobility and base of support dimensions. The advantages of larger foot placement angles on improving the relative reliability of postural stability could be better demonstrated in healthy people under challenging conditions such as standing with closed eyes. ConclusionStanding with foot placement angles between 0° and 45° are reliable and a quantitative assessment of the center of pressure could be used to monitor the changes in postural stability between sessions.

Intersession reliability of lower limb muscle strength assessments in adults with obesity eligible for bariatric surgery.

The aim of this study was to examine the test-retest reliability in lower limb muscle strength and rate of torque development (RTD) using isokinetic dynamometry in adults with obesity, with a body mass index (BMI) ≥ 35 kg/m2. Thirty-two adults with a BMI of 43.8 ± 6.6 kg/m2 eligible for bariatric surgery were enroled in the study. Isokinetic and isometric knee extensor (KE) and flexor (KF) strength were assessed in an isokinetic dynamometer (Biodex 4) during three test sessions separated by 3-7 days. There were no statistical differences in peak KE and KF torque for any test modalities between sessions. Intraclass correlation (ICC) was 0.91-0.94 between sessions 1 and 2 and 0.94-0.97 between sessions 2 and 3. Standard error of measurement (SEM%) and coefficient of variation (CV) ranged across test sessions from 4.3% to 7.3%. KE RTD showed high test-retest reliability following familiarization, with ICC, CVand SEM% values ranging from 0.84 to 0.90, 13.3%-20.3%and 14.6%-24.9%, respectively. Maximal lower limb muscle strength measured by isokinetic dynamometry showed excellent test-retest reliability manifested by small measurement errors and low CV. Reliability was slightly improved by including a familiarization session. KE RTD but not KF RTD demonstrated high test-retest reliability following familiarization. The present data indicate that isokinetic dynamometry can be used to detect even small changes in lower limb muscle strength in adults with obesity.

Single-session measures of quadriceps neuromuscular function are reliable in healthy females and unaffected by age.

This study aimed to determine the inter-session reliability of quadriceps neuromuscular function measurements in healthy young and older females. Twenty-six females aged 19-74 years completed two identical experimental sessions on different days. Quadriceps neuromuscular function measurements included isometric maximal voluntary force, high- and low-frequency twitch force, voluntary and evoked(H-reflex, M-wave) electromyography (EMG), and estimatedmaximal torque, velocity and power derived from torque-velocity relationships. Intra-class correlation coefficients (ICCs), coefficients of variation (CoV) and Bland-Altman plots assessed inter-session reliability. The effect of age on reliability was assessed by linear regression. Excellent reliability (ICC > 0.8) was shown for all voluntary and evoked mechanical outcomes. Vastus lateralis EMG outcomes showed excellent reliability (ICC > 0.8) with CoVs < 12%, which were better than those of vastus medialis and rectus femoris. Age was not associated with reliability for 27/28 outcomes (P > 0.05). Excellent reliability of voluntary and evoked force and vastus lateralis EMG outcomes measured in healthy females can be attained in one experimental session, irrespective of age. Female neuromuscular function can be accurately assessed across the lifespan with minimal inconvenience, increasing feasibility for future research. The random error should however be considered when quantifying age-related differences in neuromuscular function.

KOJI AWARENESS, a self-rating whole-body movement assessment system, has intersession reliability and comparability to external examiner rating.

KOJI AWARENESS is a newly developed self-rating whole-body movement assessment system that includes 11 domains and 22 tests. The primary aim of this study was to investigate the intersession reliability of KOJI AWARENESS, and the secondary aim was to determine whether a fixed bias existed between self-rating and external examiner rating. Fifty university students rated their movement ability in two separate sessions; an external examiner also rated the students' movement ability. Participants were blinded to their scores at the first session as well as the external examiner's rating scores. The primary analysis included examining the intersession reliability of the total score with intraclass correlation coefficients (ICCs). ICC values were interpreted as follows: insufficient, < .7 and sufficient, ≥ .7. To achieve the secondary aim, Bland-Altman analysis was performed. ICC for the intersession reliability was .86 with a 95% confidence interval (CI) of .77 to .92 and a minimum detectable change (MDC) of 5.15. Bland-Altman analysis revealed fixed bias as the 95% CIs of the mean difference between the two different rating scores (-3.49 to -2.43 and -3.94 to -2.98 in the first and second sessions, respectively) did not include 0 in the data of each session. However, no proportional bias was identified because no statistically significant Pearson's correlation (P > .05) was noted between the means of the two methods and the mean difference between the two different methods in each session. This study identified that KOJI AWARENESS has sufficient intersession reliability among relatively young and healthy participants. External examiner rating tended to have lower total scores than self-rating; however, the bias was below the MDC and seemed not to be clinically significant.

Feasibility, reliability and validity of self-measurement of knee range-of-motion using an accelerometer-based smartphone application by patients with total knee arthroplasty.

Limited knee range-of-motion (ROM) is common following total knee arthroplasty (TKA). It is associated with functional limitations and patient dissatisfaction. Regular knee ROM assessment is important but accurate testing traditionally requires timely access to trained healthcare professionals. Although accelerometer-based smartphone goniometry has shown to provide reliable and valid joint angles, current evidence of its use still positions healthcare providers as end users instead of patients themselves. Therefore, to maximize the impact of smartphone goniometry on post-TKA care, our study aimed to examine the feasibility, reliability, and validity of patients' self-measurement of knee ROM using an accelerometer-based smartphone goniometry application. Patients were given standard instructions with a practice trial before the actual measurements. Passive knee flexion and extension ROM was measured on 2 sessions in 30 patients with TKA using 4 block-randomized methods: (i) smartphone self-assessment, (ii) long-arm goniometry by physiotherapist, (iii) smartphone assessment by physiotherapist, and (iv) extendable-arm goniometry by physiotherapist with placement adjudication. Feasibility was assessed by the number of participants who could independently perform the self-measurement. To assess intra- and inter-session reliability, we computed intraclass correlation coefficients (ICCs) from random-effects models. To assess intra- and inter-session agreement, we computed mean absolute differences (MADs) and minimum detectable change (MDC). To assess concurrent validity, we designated extendable-arm goniometry as the "gold standard" and compared other methods against it using ICCs and MADs. All patients were able to comprehend and execute the assessment. 87% (n = 26) found the application easy to administer. Smartphone goniometry by patients showed excellent intra- and inter-session reliability (ICCs>0.97) and minimum variability (MAD = 0.9°-3.9°; MDC95 = 3.1°-9.0°). Smartphone or long-arm goniometry by physiotherapists did not outperform patients' self-assessment (ICC = 0.96-0.99, MAD = 0.7°-3.1°; MDC95 = 2.2°-8.0°). Compared against extendable-arm goniometry, smartphone goniometry by patients measured knee flexion and extension ROM with a MAD of 4.5° (ICC, 0.97) and 2.2° (ICC = 0.98), respectively. Our study demonstrates that smartphone goniometry is feasible, reliable and accurate, and can be used with confidence in the self-assessment of knee ROM post-TKA. Future studies should further explore its utility in telemonitored rehabilitation, and its possible integration into mobile health applications to enhance accessibility to care following TKA.

Development and assessment of test-retest reliability of a new field test to evaluate lower-limb muscle fatigability in young adults

We aimed to develop a new field test to evaluate lower-limb muscle fatigability in young adults. In Experiment–A, we developed and determined the ability of an intermittent isometric wall-squat test to induce progressive level of muscle fatigability, as detected by the kinetics of changes in squat-jump height (SJH) and sit-to-stand time (STST) computed using two smartphone applications for feasibility purposes. In Experiment–B, participants performed the same test on two different days for reliability assessment. Kinetics of changes in our fatigability indicators were registered at isotime, exhaustion, and Post2min. The minimal detectable change (MDC95) and the absolute (CVTE) and relative (ICC3-1) reliability coefficients were assessed. In Experiment–A, we reported a progressive decrease in performance for SJH and STST throughout the task, reaching at exhaustion mean changes of −22±11% and +31±13%. Individual data-analysis showed decrease in performance for SJH and STST greater than the MDC95 in 85% and 95% of participants. In Experiment–B, changes in our fatigability indicators demonstrated excellent inter-session reliability at isotime, exhaustion and Post2min for SJH (ICC3-1 &gt; 0.97; CVTE &lt; 7.5%) and STST (ICC3-1 &gt; 0.92; CVTE &lt; 3.3%). This test is feasible and reliable, making it very promising for evaluating muscle fatigability in applied (e.g. clinical) and laboratory settings.

Remote assessment of pelvic kinematics during single leg squat using smartphone sensors: Between-day reliability and identification of acute changes in motor performance.

The biomechanical assessment of pelvic kinematics during a single leg squat (SLS) commonly relies on expensive equipment, which precludes its wider implementation in ecological settings. Smartphone sensors could represent an effective solution to objectively quantify pelvic kinematics remotely, but their measure properties need to be evaluated before advocating their use in practice. This study aimed to assess whether measures of pelvic kinematics collected remotely using smartphones during SLS are repeatable between days, and if changes in pelvic kinematics can be identified during an endurance task. Thirty-three healthy young adults were tested remotely on two different days using their own smartphones placed on the lumbosacral region. Pelvic orientation and acceleration were collected during three sets of seven SLS and an endurance task of twenty consecutive SLS. The intersession reliability was assessed using Intraclass Correlation Coefficient (ICC2,k), Standard Error of Measurement, and Minimal Detectable Change. T-tests were used to identify pelvic kinematics changes during the endurance task and to assess between-day bias. Measures of pelvic orientation and frequency features of the acceleration signals showed good to excellent reliability (multiple ICC2,k ≥ 0.79), and a shift of the power spectrum to lower frequencies on the second day (multiple p<0.05). The endurance task resulted in larger contralateral pelvic drop and rotation (multiple p<0.05) and increased spectral entropy (multiple p<0.05). Our findings demonstrate that reliable measures of pelvic kinematics can be obtained remotely using participants' smartphones during SLS. Smartphone sensors can also identify changes in motor control, such as contralateral pelvic drop during an endurance task.