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Active video games (AVG) have been used as training tools and are known to ameliorate balance performance in children with Developmental Coordination Disorder (DCD). Our aim was to evaluate balance using clinical tests and by measuring body sway using a force plate with a mixed design of vision (eyes open/eyes closed), surface (rigid/soft). and support (stance/semitandem) before, and after, training and 4 months later (follow-up). Thirty-six DCD children and 40 typically developing children participated in the study, of which 50 children (26 DCD; 24 typically developing) were retested after 4 months. Balance improved on the clinical measures after the training, which was independent of type of AVG (Wii-Fit and Xbox Kinect) used, and this effect was still present after 4 months. The AVG training did not influence general sway behavior, but only sway in the eyes-open condition. corresponding with task demands of the training and indicating a training-specific effect. Overall, DCD children and typically developing children responded comparably to the AVG training, thereby maintaining the gap in performance between the two groups. The changes iii postural sway are interpreted as a sign of more confidence and less freezing of the joints, enabling greater flexibility of movements and balance strategies as supported by the improved performance on balance tests in the DCD children. This is the first study that showed long-term effects of AVG training on balance performance. However. these follow-up results should be interpreted with caution given that 35% of the children were lost in follow-up. [ABSTRACT FROM AUTHOR]

The hamstring plays an important role in reducing loads born by the anterior cruciate ligament. As anterior cruciate ligament injuries occur rapidly after ground contact, how the hamstring is activated prior to landing can influence injury risk. The purpose was to determine sex-related differences in hamstring activation immediately before landing and the effect of fatigue on "preactivation." Twenty-four participants (13 males and 11 females, age = 24.3 [6.5] y, mass = 72.2 [19.3] kg, height = 169 [9.7] cm) participated in this study. Participants completed a drop-vertical jump protocol before and after a lower body fatigue protocol. Hamstring electromyography (EMG) amplitude at 5 periods prior to landing, peak vertical ground reactions forces (in newtons/body weight), rate of loading (in body weight/second), and landing error scoring system were measured. Females had higher EMG amplitude before and after fatigue (P <.024), with decreased EMG amplitude for both sexes after fatigue (P =.025). There was no change on vertical ground reaction force, rate of loading, or landing error scoring system. Males and females demonstrated similar landing performance before and after fatigue but have different hamstring neuromuscular coordination strategies. The acute reduction in hamstring EMG amplitude following fatigue may increase loading on the anterior cruciate ligament. [ABSTRACT FROM AUTHOR]

A force plate is mainly used in biomechanics; it aims to measure the ground reaction force in a persons walking or standing position. In this study, a large-area force mat of the piezoresistance sensing type was developed, and a deep-learning-based weight measurement calibration method was applied to solve the problem in which measurements are not normalized because of physical limitations in hardware and signal processing. The test set was composed of the values measured at each point by weight and the value of the center of the pressure variable, and the measured value was predicted using a deep neural network (DNN) regression model. The calibration verification results show that the average weight errors range from a minimum of 0.06% to a maximum of 3.334%. This is simpler than the previous method, which directly measures the ratio of the resistance value to the measured weight of each sensor and derives an equation.

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The objective of this study was to assess the concurrent validity of the Kunwei force plate system in relation to variables during a counter-movement jump (CMJ) task, in comparison to the Kistler in-ground force plate system, which is considered the "gold standard". Methods: In a single testing session, the Kunwei force plates were placed directly on top of the in-ground Kistler force plate. This allowed for the simultaneous collection of vertical ground reaction forces from 30 participants (male, age = 22.8 ± 2.8 years, body mass = 74.3 ± 12.3 kg, height 178.2 ± 4.6 cm) during CMJ tests. The consistency between force plate systems was assessed using ordinary least products regression (OLPR) with bootstrapped 95% confidence intervals and the Interclass Correlation Coefficient (ICC). Results: There was no fixed or proportional bias in the CMJ variables measured between the force plate systems. The variables exhibited a strong correlation across the force plates during the CMJ task (ICC > 0.950, p < 0.01). Conclusion: The findings of this study indicate that there was no statistical difference between the Kunwei and Kistler force plate systems when evaluating common CMJ strategy and outcome variables, which are considered the gold standard. Hence, the Kunwei force plate can be regarded as a reliable substitute for the established industry benchmark in evaluating the force–time characteristics of the CMJ. Researchers, athletes, and coaches have the option to utilize this affordable and portable choice as a substitute for the more expensive laboratory-based force plate system. This alternative allows for the precise measurement of CMJ performance and force–time variables. [ABSTRACT FROM AUTHOR]

High vertical ground reaction forces (VGRF) during landings following acrobatic elements in artistic gymnastics is associated with trunk and lower extremity injury risk. As similar data regarding injury risk factors in cheerleading are scarce, the purpose of this study was to assess VGRF in pop-off dismounts of rested and fatigued flyers in cheerleaders. Fifteen German cheerleaders were recruited for this study, including seven female flyers and eight male bases. It was expected that performance would change in fatiguing athletes, potentially increasing the risk for injuries. However, neither the mean VGRF (rested: 6.0 ± 1.9BW, fatigued: 6.2 ± 1.3 BW, overall range: 2.1-14.9 BW) nor the individual VGRF-time courses of the flyers changed significantly after the workout. Instead, we show that the flyers' ability to land -- but not the bases' ability to catch -- significantly influences the maximum and time-resolved impacts. [ABSTRACT FROM AUTHOR]

Study Design. Longitudinal observational cohort. Objectives. The purpose of this study was to evaluate the utility of Quantitative Romberg measurements as pre-op and post-op balance outcome measures. Summary of Background Data. Cervical spondylotic myelopathy (CSM) is characterized by balance deficiencies produced by impaired proprioception. Evaluation is subjective, and binary physical exam findings lack the precision to assess postoperative outcome improvement. Methods. CSM patients were prospectively enrolled to undergo preoperative and postoperative Quantitative Romberg tests on a force plate to record center of pressure (COP) motion for 30 seconds with eyes open followed by eyes closed. Revision cases were excluded. Kinematics of COP movement parameters were compared between preoperative and postoperative state for each patient. Results. Twenty-seven CSM patients were enrolled and completed both pre/post-testing. The mean age was 60.0 years, with 13 (48%) males and 9 (33%) smokers. Mean number of surgical levels was 2.48. The minimum mean follow-up was six months. There was a statistically significant improvement in eyes closed after surgery compared with preoperative for total COP motion (523.44 vs. 387.00 cm, P<0.001), average sway speed (17.41 vs. 13.00 cm/s, P< 0.001), and total lateral COP motion (253.44 vs. 186.70 cm, P<0.001). There was no statistically significant improvement in the modified Japanese Orthopaedic Association (13.29 vs. 14.29, P=0.28). Conclusions. CSM balance findings on Quantitative Romberg testing significantly improve postoperatively in patients with CSM. These findings support this testing as representative of proprioceptive balance deficiencies seen in CSM. Quantitative Romberg may be used as an objective measure of clinical outcome and assist in stratification of surgical interventions, surgery timing, and technique. [ABSTRACT FROM AUTHOR]

To evaluate the concurrent validity and test–retest reliability of common movement, strength, and balance tests using portable uniaxial dual force plates. Repeated measures cross-sectional study. Sixteen healthy individuals participated in two testing sessions, where they performed 12 different movement, strength, and balance tests. Vertical ground reaction force and centre of pressure data were collected using the VALD ForceDecks simultaneously with ground-embedded laboratory force plates. Concurrent validity was assessed using root mean square error for raw time-series data and Bland–Altman plots for discrete metrics. Test–retest reliability was assessed using intraclass correlation coefficients and minimal detectable changes. ForceDecks recorded vertical ground reaction forces and center of pressure with high accuracy compared to laboratory force plates. The mean bias between systems was negligible (<2 N or 0.1 mm), with small limits of agreement (<5 N or 1 mm). Overall, 530/674 (79%) showed good or excellent validity (<10% difference) and 611/773 (79%) had good or excellent reliability (intraclass correlation coefficient >0.75). ForceDecks reliability was similar to laboratory force plates (<0.07 intraclass correlation coefficient median difference for all metrics). Portable uniaxial force plates record highly accurate vertical ground reaction forces and center of pressure during a range of movement, strength, and balance tests. The VALD ForcDecks are a valid and reliable alternative to laboratory force plates when strict standardized testing and data analysis procedures are followed. Users should be aware of the validity and reliability characteristics of the tests and metrics they choose. [ABSTRACT FROM AUTHOR]

Background: This scoping review summarizes the tasks and outcomes in dynamic and functional balance assessments of individuals with chronic ankle instability, focusing on the physiological and biomechanical characteristics. Method: A comprehensive literature search was conducted in PubMed, Scopus, Web of Science, and MEDLINE databases in September 2023 and revised in April 2024. Studies evaluating dynamic and functional balance in chronic ankle instability using clinical tests, as well as biomechanical and physiological outcomes, were included. Results: Out of 536 publications, 31 met the screening criteria. A history of ankle sprain was the main focus of the inclusion criteria (28 articles, 90%). The star excursion balance test, emphasizing maximum reach distance, was the most common quantitative task (12 articles, 66%). Physiological data mainly came from electromyography studies (7 articles, 23%), while biomechanical variables were often assessed through center of pressure studies using force plates (17 articles, 55%). Conclusions: The preferred quantitative clinical assessment was the star excursion balance test, focusing on normalized reach outcomes. Qualitative functional balance assessments emphasize landing activities and center of pressure displacement. Electromyography is commonly used to analyze the tibialis anterior and peroneus longus muscles. However, there is a lack of qualitative data on dynamic balance control, including morphological characteristics and the center of mass adaptation. [ABSTRACT FROM AUTHOR]

Objectives: Menopause and aging-related hormonal changes lead to declines in muscle strength and mass in women. The World Health Organization and American College of Sports Medicine both recommend that older adults should engage in multicomponent exercise. This study investigated the effects of multicomponent exercise, detraining, and retraining on muscle performance in postmenopausal women. Methods: Thirty-three postmenopausal women (age: 67.2 ± 5.3 years) were randomly assigned to an experimental or a control group. The experimental group underwent 12 weeks of multicomponent exercise followed by 12 weeks of detraining and 8 weeks of retraining; the control group maintained their normal lifestyle. Regarding mechanical characteristics, the sit-to-stand test was performed and the skeletal muscle mass index (SMI) measured at four time points: before training, after 12 weeks of training, after 12 weeks of detraining, and after 8 weeks of retraining. The mechanical parameters measured were the peak ground reaction force (GRF), time to reach peak force, and time from sitting to standing, which can be used to assess lower-limb muscle strength, contraction speed, and dynamic balance. Results: The peak GRF and SMI of the experimental group were significantly better than those of the control group after the training, decreased during the detraining, but then rapidly recovered during the retraining. Conclusions: Multicomponent exercise enhances muscle strength and mass in postmenopausal women. The results of this study can serve as a reference for the design of community-based exercise programs. [ABSTRACT FROM AUTHOR]

Gait initiation (GI) is a functional task classically used in the literature to evaluate the capacity of individuals to maintain postural stability. Postural stability during GI can be evaluated through the "margin of stability" (MoS), a variable that is often computed from force plate recordings. The markerless motion capture system (MLS) is a recent innovative technology based on deep learning that has the potential to compute the MoS. This study tested the agreement between a force plate measurement system (FPS, gold standard) and an MLS to compute the MoS during GI. Healthy adults (young [YH] and elderly [EH]) and Parkinson's disease patients (PD) performed GI series at spontaneous (SVC) and maximum velocity (MVC) on an FPS while being filmed by a MLS. Descriptive statistics revealed a significant effect of the group (YH vs. EH vs. PD) and velocity condition (SVC vs. MVC) on the MoS but failed to reveal any significant effect of the system (MLS vs. PFS) or interaction between factors. Bland–Altman plot analysis further showed that mean MoS biases were zero in all groups and velocity conditions, while the Bayes factor 01 indicated "moderate evidence" that both systems provided equivalent MoS. Trial-by-trial analysis of Bland–Altman plots, however, revealed that differences of >20% between the two systems did occur. Globally taken, these findings suggest that the two systems are similarly effective in detecting an effect of the group and velocity on the MoS. These findings may have important implications in both clinical and laboratory settings due to the ease of use of the MLS compared to the FPS. [ABSTRACT FROM AUTHOR]

This study aimed to 1) identify what starting block outcome kinetics have the greatest relationship to 15 m start time; 2) investigate key mechanistic determinants of the block phase and how these forces are sequenced. One hundred and fifty-two high-level competitive swimmers were included in the study. Linear mixed modelling identified four on-block outcome kinetic variables (work, average power, horizontal take-off velocity (HTOV), and average acceleration) as having a very large relationship (R2 = 0.79–0.83) to 15 m start time, with average power having the most substantial impact. On-block force sequencing started with the rear leg, followed by upper limb grab forces and the front leg. Further exploration of underlying determinants was performed for average power and HTOV of the centre of mass. Multiple linear regression identified grab resultant peak force, rear resultant average force, front horizontal peak force, and resultant peak force as significant predictors of average power (R2 = 0.88). HTOV was predicted using the same variables, apart from the inclusion of rear horizontal peak force instead of rear resultant average force (R2 = 0.73). These findings may influence how strength and conditioning and skill acquisition interventions are designed to improve swim start performance. [ABSTRACT FROM AUTHOR]

Assessing postural control is important for the assessment of motor function after concussion. Data used for postural control assessment typically do not take the sport played, age, or sex of the athlete into consideration. It is plausible these variables may be significant when making return-to-play decisions. This study used the BTrackS database to examine differences in postural control in athletes playing different types of sports and across sex and age. BTrackS data from 9093 high school to college-aged athletes (aged 14–22 years) were examined employing a One-way ANOVA with a post-hoc test to compare CoP path length between sport types. A moderation analysis was used to test interaction effects of sex and age on a CoP/BMI ratio. Significant differences were observed between sport types, F(3,9089) = 42.4, p <.001, η2 = 0.014. Post hoc tests indicated that collision (M = 25.0, SD = 7.6) sport athletes exhibited significantly higher CoP measures compared to the contact (M = 23.4, SD = 7.4), limited contact (M = 22.9, SD = 6.9), and non-contact (M = 23.0, SD = 7.4) athletes. There was no difference between other sport types (p >.20). A significant mean sex difference (Mmale = 0.924, Mfemale = 0.898, p <.001) and a quadratic association with age, (β = −0.042, p <.001) was observed. Further, magnitude of those age differences decreased with age (β = 0.011, p <.001). An interaction of age and sex was significant for linear (β = 0.020, p <.001) and quadratic terms (β = −0.006, p <.001). Athletes exhibited different postural control when the type of sport, age, and sex was taken into consideration. This data possess clinical significance as this suggests that normative postural control data for collision sport athletes should be derived from data based upon type of sport played, age, and sex of the athlete. • Over 9000 balance tests were analyzed, based on frequency and level of contact. • Balance data used for return-to-play decisions should be from similar sports. • Collision sports athletes display significantly different balance performance. [ABSTRACT FROM AUTHOR]

IntroductionThe response to medical management of young dogs with osteoarthritis (OA) associated pain has not been evaluated. Using an open-label design, the effectiveness, over a 4-month period, of standardized management (grapiprant/fish oil/exercise) for treating OA pain in young dogs was evaluated.MethodsIncluded dogs were 9 months-4 years of age; ≥3.6 kg body weight; had ≥1 appendicular joint with radiographic OA and obvious joint pain; had a Liverpool Osteoarthritis in Dogs (LOAD) score of ≥5. The non-steroidal anti-inflammatory piprant (grapiprant) was given at the recommended dose daily, omega-3 fatty acid supplementation was initiated at 100 mg/kg and then increased to 200 mg/kg daily, and leash exercise was gradually increased to a target of 60 min daily. Client-reported outcome measures (CROMs) and force plate gait analysis were collected at baseline and monthly for 4 months. The index limb was defined as the most severely affected limb at baseline.ResultsForty-eight dogs were enrolled (mean ± SD age of 30.7 ± 10.7 months). Hips, elbows, and stifles were commonly affected. Medication and supplement compliance was excellent (≥95% of target administered), and treatments were well-tolerated. CROMs showed significant improvement over time and at each time point. Overall, peak vertical force (PVF) increased significantly (

Introduction & Purpose Postural control is essential for maintaining balance during static and dynamic tasks. It is typically measured by centre of pressure (CoP) deviations using a ground reaction force plate (FP). Alternatively, more affordable and accessible accelerometer-based measures have been proposed. However, no consensus on the best protocol exists (Pinho et al., 2019). This study investigates the feasibility of assessing postural sway using linear acceleration data, considering sensor placement, task difficulty and analysed parameters. Methods The University of Vienna Ethics Committee approved this study (Ref. Nr. 01108). Ten healthy adults (6 M/4 F; 37.9 ± 14.8 years; BMI = 23.3 ± 2.3) performed eleven balance tasks, seven easy tasks from the Berg Balance Scale and four harder tasks with eyes closed, each lasting 20 seconds. Postural sway was assessed using a FP and five inertial measurement units (IMUs) attached to the upper spine (C7), lower spine (L1), sacrum and both thighs. Data were synchronously collected at 1500 Hz, zeroed, band pass filtered (3rd order Butterworth, 0.3-10 Hz; Martinez-Mendez et al., 2012), and cropped to 19 s. Outcomes included CoP path length, root mean square of sway amplitude in the anteroposterior (AP) and mediolateral (ML) directions for the FP, and RMS of the linear acceleration in AP and ML directions, along with their sum, for the ACC. Combinations of the two AP, two ML and two overall parameters were analysed by winsorised Pearson correlations and Bland Altman limits of agreement of z-scores for each task and for each sensor site. Fisher's Z-transformed correlation coefficients and limits of agreement were compared across task difficulty, parameter combinations, and sensor placement sites using a 3-way ANOVA. Results Pearson coefficients correlating the ACC parameters with the FP parameters averaged 0.60 (95% CI [0.54, 0.66]) for the easy tasks and 0.78 (95% CI [0.726, 0.84]) for the hard tasks, with no significant differences between sensor sites. A significant interaction (p < 0.001) was found between task difficulty and parameter combination. Simple main effect analysis showed no difference between correlations of AP, ML and overall parameters for hard tasks but for easy tasks, where overall parameters showed the highest correlation, followed by ML and then AP parameters, all differing significantly from each other. The Bland Altman mean difference of z-scores between FP and ACC parameters was on average -0.002 (95% CI [-0.027, 0.024]). The lower and upper limits of agreement were on average -0.72 (95% CI [-0.84, -0.62]) and 0.73 (95% CI [0.62, 0.83]) respectively. Discussion The correlations between FP and ACC were higher during more challenging tasks, while the limits of agreement were broader and less precise in these tasks (data not shown). No optimal sensor placement site was identified as correlation and agreement between the two methods did not differ significantly between sites. The broad limits of agreement suggest relatively low precision of ACC measures compared to FP. Overall parameters often outperformed ML and AP parameters in terms of correlation and precision. Conclusion Accelerometer-based measures of postural sway showed high correlations with force plate measures but low precision when tasks where difficult enough to challenge participants’ balance. Sensor placement site did not influence correlation and precision. References Pinho, A. S., Salazar, A. P., Hennig, E. M., Spessato, B. C., Domingo, A., & Pagnussat, A. S. (2019). Can we rely on mobile devices and other gadgets to assess the postural balance of healthy individuals? A systematic review. Sensors, 19(13), Article 13. https://doi.org/10.3390/s19132972 Martinez-Mendez, R., Sekine, M., & Tamura, T. (2012). Postural sway parameters using a triaxial accelerometer: Comparing elderly and young healthy adults. Computer Methods in Biomechanics and Biomedical Engineering, 15(9), 899–910. https://doi.org/10.1080/10255842.2011.565753

High vertical ground reaction forces (VGRF) during landings following acrobatic elements in artistic gymnastics is associated with trunk and lower extremity injury risk. As similar data regarding injury risk factors in cheerleading are scarce, the purpose of this study was to assess VGRF in pop-off dismounts of rested and fatigued flyers in cheerleaders. Fifteen German cheerleaders were recruited for this study, including seven female flyers and eight male bases. It was expected that performance would change in fatiguing athletes, potentially increasing the risk for injuries. However, neither the mean VGRF (rested: 6.0±1.9 BW, fatigued: 6.2±1.3 BW, overall range: 2.1–14.9 BW) nor the individual VGRF-time courses of the flyers changed significantly after the workout. Instead, we show that the flyers’ ability to land – but not the bases’ ability to catch – significantly influences the maximum and time-resolved impacts.

Abstract This study investigates the relationship between ankle and toe strength and functional stability in young adults, with a sample comprising sixteen females and fourteen males. The research employed force platform data to determine the center of foot pressure (COP) and calculated the forward functional stability index (FFSI) through foot anthropometric measurements. Strength measurements of toe and ankle muscles, during maximal isometric flexion and extension, were conducted using force transducers. Notable positive correlations were found between toe flexor strength and FFSI (left flexor: r = 0.4, right flexor: r = 0.38, p

This study examined the validity and intrarater reliability of a newly developed portable force platform designed to estimate vertical jump height. Thirty-two healthy, recreationally active sports science students (20 males and 12 females) participated. A total of 64 countermovement jumps (with arm swing) were simultaneously recorded using 2 instruments: the Optojump photoelectric system (Microgate, Bolzano, Italy) as the criterion instrument, and the portable force plate (iVMES, Ankara, Turkey) as the practical instrument, to evaluate validity and reliability. The concurrent validity of the iVMES portable force plate system was examined using the Pearson's correlation coefficient with 95% confidence intervals and limits of agreement. The typical error of estimate was reported, and Bland-Altman plots were created to evaluate the agreement between the 2 measurement devices. The test-retest reliability of the iVMES force plate was assessed using the intraclass correlation coefficient with a 95% confidence interval. Additionally, metrics such as the smallest error of measurement, smallest worthwhile change, minimum detectable change, and root mean square error were calculated to assess the absolute reliability. Compared with the criterion instrument, the iVMES force plate produced vertical jump height values with an excellent intraclass correlation coefficient (0.98) and a very low bias (0.14 cm). Furthermore, the testretest reliability was outstanding, with a low coefficient of variation (3.8%) and a strong intraclass correlation coefficient (0.96) for vertical jump height. The measurements from the 2 devices displayed extremely low smallest error of measurement and smallest worthwhile change values (both 0.05), as well as minimum detectable change (0.14) values. These findings confirmed a minimal and acceptable margin of error between the 2 measurements. In conclusion, the iVMES portable force plate demonstrated strong concurrent validity and excellent test-retest reliability for estimating vertical jump height. [ABSTRACT FROM AUTHOR]

Concussions among the athletic population are extremely common, which could lead to postural instabilities. The purpose of this study was to assess the effect of concussions on postural stability in young healthy adults. The static postural stability of thirty volunteers (age 21.63 ± 2.50 years; height 1.70 ± 0.14 m; weight 75.00 ± 15.58 kg; 17 with a history of concussions) was assessed using a force platform during three tests: baseline stability test, clinical test of sensory interaction and balance test, and unilateral stability test. Postural sway variables during each test were statistically analyzed using an independent t-test between the concussion group (CONC) and no concussion (NO CONC) groups. Two secondary analyses were performed with the CONC group: individuals who had one concussion (ONCE) vs. who had multiple concussions (MULTIPLE) and individuals who had their last concussion in 2023–2018 (RECENT) and in 2017–2011 (OLD). The CONC, MULTIPLE, and RECENT groups demonstrated greater postural sway than the NO CONC, SINGLE, and OLD groups. Concussions cause postural decrements in young healthy adults compared to their counterparts with no history of concussions. The results of the study exhibit that concussions could lead to imbalances, which is decisive in athletes' performance and injury risk during play. [ABSTRACT FROM AUTHOR]

Purpose: Comprehensive understanding of force plate parameters distinguishing individuals postprimary anterior cruciate ligament reconstruction (ACLR) from healthy controls during countermovement jumps (CMJ) and/or drop jumps (DJ) is lacking. This review addresses this gap by identifying discriminative force plate parameters and examining changes over time in individuals post‐ACLR during CMJ and/or DJ. Methods: We conducted a systematic review and meta analyses following the Preferred Reporting Items for Systematic Review and Meta‐Analyses (PRISMA) guidelines. Nine databases were searched from inception to March 2022. We included cross‐sectional papers comparing post‐ACLR with healthy controls or longitudinal studies of individuals at least 6 months postprimary ACLR while performing CMJ and/or DJ on force plates. The methodological quality was appraised using the Modified Downs and Black Checklist. Results: Thirty‐three studies including 1185 (50.38%) participants post‐ACLR, and 1167 (49.62%) healthy controls, were included. Data were categorised into single‐leg CMJ, double‐leg CMJ, single‐leg DJ, and double‐leg DJ. Jump height was reduced in both single (mean difference [MD] = −3.13; p < 0.01; 95% confidence interval [CI]: [−4.12, −2.15]) and double‐leg (MD = −4.24; p < 0.01; 95% CI: [−5.14, −3.34]) CMJs amongst individuals with ACLR. Similarly, concentric impulse and eccentric/concentric impulse asymmetry could distinguish between ACLR (MD = 3.42; p < 0.01; 95% CI: [2.19, 4.64]) and non‐ACLR (MD = 5.82; p < 0.01; 95% CI: [4.80, 6.80]) individuals. In double‐leg DJs, peak vertical ground reaction forces were lower in the involved side (MD = −0.10; p = 0.03; 95% CI: [−0.18, −0.01]) but higher in the uninvolved side (MD = 0.15; p < 0.01; 95% CI: [0.10, 0.20]) when compared to controls and demonstrated significant changes between 6 months and 3 years post‐ACLR. Conclusion: This study identified discriminative kinetic parameters when comparing individuals with and without ACLR and also monitored neuromuscular function post‐ACLR. Due to heterogeneity, a combination of parameters may be required to better identify functional deficits post‐ACLR. Level of Evidence: Level III. [ABSTRACT FROM AUTHOR]

In this study, the novel mobile dynamometric platform, OREKA, was utilized to perform an extensive analysis of the centre of pressure behaviour during different tilt motion exercises. This platform is based on a parallel manipulator mechanism and can perform rotations around both horizontal axes and a vertical translation. A group of participants took part in an experimental campaign involving the completion of a set of exercises. The aim was to evaluate the platform's potential practical application and investigate the impact of visual on-screen feedback on centre of pressure motion through multiple balance indicators. The use of the OREKA platform enables the study of the impact on a user's balance control behaviour under different rotational perturbations, depending on the availability of real-time visual feedback on a screen. Furthermore, it presented data identifying postural control variations among clinically healthy individuals. These findings are fundamental to comprehending the dynamics of body balance. Further investigation is needed to explore these initial findings and fully unlock the potential of the OREKA platform for balance assessment methodologies. [ABSTRACT FROM AUTHOR]

This study examined the effects of range of motion (ROM) on applied force, power output and surface electromyographic (sEMG) responses during repeated sets of bench press exercise executed as fast as possible. Ten resistance trained men performed three sets to momentary failure with two-min rest intervals under three different ROM conditions: (a) full ROM (FULL), (b) TOP, at the top half of ROM, and (c) BOTTOM, at the bottom half of ROM. Mean and peak force were higher in TOP compared to FULL and BOTTOM (mean force: 817 ± 80 vs. 657 ± 98 vs. 623 ± 122 N, respectively, p < 0.001) with no differences between FULL and BOTTOM. During repeated sets, large decreases were found in peak (by 29.4 to 45.3%) and mean power (by 55.5 to 64.7%) from the first to the last repetitions. However, the decrease in mean force was only 2% (p < 0.01) and decreases in peak force ranged from 6.7 and 8.8% to zero, indicating the velocity loss was the main contributor to fatigue in power output. Although force and power output in set 3 were unchanged in BOTTOM, mean power output decreased significantly, suggesting that lower performance and fatigue may be related to the longer muscle length. Fatigue was accompanied by an increase in sEMG activity and a decrease in median frequency in all muscles, with triceps brachialis sEMG reflecting more the force and power differences among ROMs. In conclusion, fatigue depends on velocity rather than force loss during bench press exercise at different ROMs. [ABSTRACT FROM AUTHOR]

This study aimed to determine the effects of different verbal instructions, intended to affect the countermovement jump (CMJ) execution time, on the reactive strength index modified (RSIMod) and the time-series waveforms. Thirteen male basketball players performed six CMJs on a force plate with two different verbal instructions: 'jump as high as possible' (CMJhigh) and 'jump as high and as fast as possible' (CMJfast). Force-, power-, velocity-, and displacement-series waveforms, RSIMod and jump height were compared between conditions using statistical parametric mapping procedures. CMJfast showed greater values in RSIMod (p = 0.002) despite no differences in jump height (p = 0.345). Unweighting force (between 18% and 33% of total time) was lower in the CMJfast compared to CMJhigh. Larger force (between 53% and 63% of total time), velocity (between 31% and 48% of total time) and power (between 43% and 56% of total time) were found in the CMJfast compared to CMJhigh. These findings suggest that commanding athletes to jump as high and fast as possible increases rapid force production. Additionally, the results highlight the relevance of the countermovement phase in jumping and show that RSIMod could increase without power output modifications during propulsion, despite previous studies having reported positive associations between RSIMod propulsion power. [ABSTRACT FROM AUTHOR]

Cabarkapa, DV, Cabarkapa, D, Philipp, NM, and Fry, AC. Competitive season-long changes in countermovement vertical jump force-time metrics in female volleyball players. J Strength Cond Res 38(2): e72-e77, 2024--Although force plates remain one of the most widely used tools for neuromuscular performance assessment in applied sports-specific settings, there is still a lack of scientific literature focused on studying changes in countermovement vertical jump (CVJ) performance in team sports such as volleyball, especially within the female athlete population. Thus, the purpose of the present study was to examine season-long neuromuscular performance changes in volleyball players. Eighteen National Association of Intercollegiate Athletics Division-I collegiate female athletes performed 3 maximal-effort CVJs while standing on a uniaxial force plate system sampling at 1,000 Hz at 5 different testing timepoints throughout a competitive season span (;11 weeks). The testing sessions were separated 2-3 weeks apart and performed at the approximately same time of the day (12:00 hours). Repeated-measures analysis of variance revealed that both concentric and eccentric force-time metrics remain relatively unchanged throughout a regular season span (e.g., concentric peak force and power, eccentric impulse and duration). However, the eccentric metrics such as peak and mean power and peak velocity displayed a slight improvement after a brief tapering period purposely implemented before the post-season competition to optimize the athlete's recovery (;15, 18, and 14% increase, respectively). In addition, the outcome metrics such as vertical jump height and reactive strength index-modified did not display notable fluctuations across the competitive season span. These findings can help coaches, sports scientists, and strength and conditioning practitioners to obtain a deeper insight into collegiate female athletes' force-time characteristics that may aid with developing adequate training regimens targeted toward optimizing on-court performance. [ABSTRACT FROM AUTHOR]

Recent advancements in motion measurement systems have facilitated the analysis of kinematic techniques in sports, emphasizing the importance of motion control for performance enhancement. Ground reaction forces and moments are crucial in biomechanical analysis, and are typically measured using force plates. However, conventional force plates pose limitations in winter sports due to their impracticality on ice. To address this, various methods have been explored, including skates equipped with strain gauges and pressure-sensitive insoles. Despite advancements, simultaneous measurement of forces and moments in three axes remains a challenge. In this study, we developed a new wearable system capable of comprehensively measuring the forces and moments during skating by attaching three wearable force plates between the boot and the blade. The precision of this measurement system was validated through an experiment employing a conventional force plate, demonstrating its high accuracy. On-ice trials confirmed the system's efficacy in capturing dynamic movements like forward sliding and half-turn jumps. The six-component force was successfully measured during skating motions, a task that is challenging with conventional systems. This system offers a promising avenue for nuanced biomechanical analysis in figure skating, facilitating insights into performance optimization and injury prevention.

The objective of this study was to assess the concurrent validity of the Kunwei force plate system in relation to variables during a counter-movement jump (CMJ) task, in comparison to the Kistler in-ground force plate system, which is considered the “gold standard”. Methods: In a single testing session, the Kunwei force plates were placed directly on top of the in-ground Kistler force plate. This allowed for the simultaneous collection of vertical ground reaction forces from 30 participants (male, age = 22.8 ± 2.8 years, body mass = 74.3 ± 12.3 kg, height 178.2 ± 4.6 cm) during CMJ tests. The consistency between force plate systems was assessed using ordinary least products regression (OLPR) with bootstrapped 95% confidence intervals and the Interclass Correlation Coefficient (ICC). Results: There was no fixed or proportional bias in the CMJ variables measured between the force plate systems. The variables exhibited a strong correlation across the force plates during the CMJ task (ICC > 0.950, p < 0.01). Conclusion: The findings of this study indicate that there was no statistical difference between the Kunwei and Kistler force plate systems when evaluating common CMJ strategy and outcome variables, which are considered the gold standard. Hence, the Kunwei force plate can be regarded as a reliable substitute for the established industry benchmark in evaluating the force–time characteristics of the CMJ. Researchers, athletes, and coaches have the option to utilize this affordable and portable choice as a substitute for the more expensive laboratory-based force plate system. This alternative allows for the precise measurement of CMJ performance and force–time variables.

Background: This scoping review summarizes the tasks and outcomes in dynamic and functional balance assessments of individuals with chronic ankle instability, focusing on the physiological and biomechanical characteristics. Method: A comprehensive literature search was conducted in PubMed, Scopus, Web of Science, and MEDLINE databases in September 2023 and revised in April 2024. Studies evaluating dynamic and functional balance in chronic ankle instability using clinical tests, as well as biomechanical and physiological outcomes, were included. Results: Out of 536 publications, 31 met the screening criteria. A history of ankle sprain was the main focus of the inclusion criteria (28 articles, 90%). The star excursion balance test, emphasizing maximum reach distance, was the most common quantitative task (12 articles, 66%). Physiological data mainly came from electromyography studies (7 articles, 23%), while biomechanical variables were often assessed through center of pressure studies using force plates (17 articles, 55%). Conclusions: The preferred quantitative clinical assessment was the star excursion balance test, focusing on normalized reach outcomes. Qualitative functional balance assessments emphasize landing activities and center of pressure displacement. Electromyography is commonly used to analyze the tibialis anterior and peroneus longus muscles. However, there is a lack of qualitative data on dynamic balance control, including morphological characteristics and the center of mass adaptation.

Purpose: To examine the reliability, validity, and performance characteristics of the 10 to 5 repeated jump test (10–5 RJT) in adolescent male athletes. The 10–5 RJT has been shown to be a valid and reliable test of reactive strength index (RSI) in older adolescents (age 17–19 y), but less is known in younger adolescent athletes at different stages of maturity. Methods: Athletes (age 11–17 y) completed the 10–5 RJT on 2 days, 1 week apart, to examine the reliability (n = 41), validity (n = 18) of the test. Athletes were classified as pre, circa, or post peak height velocity (PHV) height velocity using maturity offset to examine the effect of maturation status on RSI, flight time (FT), ground contact time (GCT), and jump height (JH) (n = 68) using a cross-sectional design. Results: Paired samples t tests showed no significant differences (P ≥.05), and Bland–Altman analysis showed no bias and close limits of agreement for RSI, JH, FT, and GCT between the contact mat and force plate. Interday reliability was rated excellent for RSI (intraclass correlation coefficient =.91) and good for GCT, FT, and JH (intraclass correlation coefficient =.81–.85). All variables had a coefficient of variation ≤ 10%. RSI increased across maturation groups, with significant differences between pre-PHV and post-PHV groups (P =.014, d = 1.00). Conclusion: The 10–5 RJT is a valid and reliable test for adolescent male athletes. Greater RSI with advancing maturity was primarily due to increased FT and JH, with GCT remaining similar. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to examine the concurrent validity of force–velocity (FV) variables assessed across 5 Keiser leg press devices. Methods: A linear encoder and 2 independent force plates (MuscleLab devices) were mounted on each of the 5 leg press devices. A total of 997 leg press executions, covering a wide range of forces and velocities, were performed by 14 participants (29 [7] y, 181 [5] cm, 82 [8] kg) across the 5 devices. Average and peak force, velocity, and power values were collected simultaneously from the Keiser and MuscleLab devices for each repetition. Individual FV profiles were fitted to each participant from peak and average force and velocity measurements. Theoretical maximal force, velocity, and power were deduced from the FV relationship. Results: Average and peak force and velocity had a coefficient of variation of 1.5% to 8.6%, near-perfect correlations (.994–.999), and a systematic bias of 0.7% to 7.1% when compared with reference measurements. Average and peak power showed larger coefficient of variations (11.6% and 17.2%), despite excellent correlations (.977 and.952), and trivial to small biases (3.9% and 8.4%). Extrapolated FV variables showed near-perfect correlations (.983–.997) with trivial to small biases (1.4%–11.2%) and a coefficient of variation of 1.4% to 5.9%. Conclusions: The Keiser leg press device can obtain valid measurements over a wide range of forces and velocities across different devices. To accurately measure power, theoretical maximal power calculated from the FV profile is recommended over average and peak power values from single repetitions, due to the lower random error observed for theoretical maximal power. [ABSTRACT FROM AUTHOR]

Context: Single-leg stability has been associated with injury risk and is a key component of many injury prevention interventions. Methods of measuring single-leg stability are varied yet often unreliable. Objective: To establish within- and between-day test–retest reliability for single-leg time to stabilization (SL-TTS) following a drop-landing maneuver of 20 cm in height among a healthy cohort. Design: Test–retest reliability study. Setting: Healthy cohort from a third-level educational institution. Participants: Nineteen (11 females and 8 males) healthy individuals. Main Outcome Measures: The SL-TTS in the vertical plane. Results: The SL-TTS showed good within-day (intraclass correlation coefficient =.715) and excellent between-day (intraclass correlation coefficient =.83) test–retest reliability. The minimal detectable change was calculated as 171.6 ms for within-day contexts and 123.8 ms for between-day contexts. Conclusions: This method of measuring SL-TTS is reliable and could be used to detect changes over time in a healthy cohort. This could be of value to clinicians in injury risk factor identification or assessing the effectiveness of single-leg stability training. However, further research is needed to investigate its reliability in pathological populations. [ABSTRACT FROM AUTHOR]

Context: Chronic ankle instability (CAI) is a common problem associated with impaired postural stability. Whole-body vibration (WBV) has been developed to improve muscle function and reportedly improves postural stability. The aim of this study was to evaluate the effect of 12 sessions of WBV on postural control during standing postural task in participants with CAI. Design: A controlled clinical trial study. Methods: Sixteen participants with CAI and 16 healthy participants aged between 20 and 40 years included in this study. They received WBV (30-Hz frequency, 3 series of four 45-s exercises with a 45-s rest) for a total of 12 sessions, 2 session per week for 6 weeks. Postural control was assessed by center of pressure (COP) parameters, including mean and SD in the anterior–posterior and medial–lateral displacement during single-leg standing. Assessments were done before and immediately after the first session and after the 12th session of WBV, with opened and closed eyes associated with easy and difficult cognitive tasks. Results: The results showed that the SD of COP displacement in the x-axis was significant in eyes opened and SD of COP displacement in the x- and y-axes were significant between groups in the eyes-opened, and eyes-closed conditions (P <.05). Analysis of variance indicated that the effect of WBV training was significant for the mean of COP displacement in the y-axis. Post hoc indicated that the effect of 12 sessions of WBV on the mean of COP displacement was significant in the CAI group (P <.05). However, the acute effect of WBV was not significant on the COP displacement in all axes (P >.05). Conclusion: Higher postural sway associated with postural cognitive interactions might be considered in the rehabilitation of CAI. Twelve sessions of WBV might induce some improvement in postural control with the method of WBV used in this study. [ABSTRACT FROM AUTHOR]

In type 1 diabetes, it is important to prevent diabetes‐related complications and postural instability may be one clinically observable manifestation early on. This study was set to investigate differences between type 1 diabetics and healthy controls in variables of instrumented posturography assessment to inform about the potential of the assessment in early detection of diabetes‐related complications. Eighteen type 1 diabetics with no apparent complications (HbA1c = 58 ± 9 mmol/L, diabetes duration = 15 ± 7 years) and 35 healthy controls underwent six 1‐min two feet standing postural stability tests on a force plate. Study groups were comparable in age and anthropometric and performed the test with eyes open, eyes closed (EC), and EC head up with and without unstable padding. Type 1 diabetics exhibited greater sway (path length, p = 0.044 and standard deviation of velocity, p = 0.039) during the EC test with the unstable pad. Also, power spectral density indicated greater relative power (p = 0.043) in the high‐frequency band in the test with EC head up on the unstable pad and somatosensory activity increased more (p = 0.038) when the unstable pad was added to the EC test. Type 1 diabetes may induce subtle changes in postural control requiring more active balancing when stability is challenged. Postural assessment using a portable easy‐to‐use force plate shows promise in detecting a diabetes‐related decline in postural control that may be used as a sensitive biomarker of early‐phase diabetes‐related complications. [ABSTRACT FROM AUTHOR]

The Balance Tracking System (BTrackS) Limits of Stability (LOS) protocol is a relatively new means of evaluating unconstrained dynamic postural control ability. While the reliability of this protocol has previously been established, reference data is currently unavailable to assist in the interpretation of results. What are typical reference values for the BTrackS LOS protocol with respect to sex, height, and BMI? A cross= -section of 800 healthy, young adults (aged 18–29 years; 368 men, 432 women) were administered the BTrackS LOS protocol. Sex, height and weight variables were also captured for the participants. Results of a stepwise linear regression showed that the outcome measure for BTrackS LOS testing (i.e. LOS Area) was larger in taller individuals and in men. Based on these findings, four percentile ranking categories were established and associated look-up tables created. The reference values provided by this study offer much needed guidance to clinicians and researchers for the determination of dynamic balance abnormalities based on BTrackS LOS testing. • First reference data for the BTrackS Limits of Stability protocol. • Taller individuals and men have larger LOS Areas then shorter individuals and women. • Percentile ranking look-up tables provided to guide future result interpretation. [ABSTRACT FROM AUTHOR]

Calf injuries are common in professional football; thus, the establishment of reliable and time-efficient methods of measuring the peak force capabilities of the plantar flexors with equipment that is accessible to football practitioners is valuable. In this study, we determined the preliminary reliability and feasibility of a new test, termed the kneeling isometric plantar flexion test (KIPFT), for footballers. Twenty-one male youth footballers (age = 17.8 ± 1.1 years, height = 182 ± 5 cm, weight = 77.6 ± 5.9 kg) from English League One football clubs completed three trials of the KIPFT on a wireless force plate at the end (2022–2023) and start (2023–2024) of the season. The within-session reliability of the peak force (relative to body weight) was good–excellent for both limbs and both occasions. On average, performance of the KIPFT took just over 1 min per limb and ~2 min to set up. The peak force values were larger for the non-dominant limbs only at the start versus the end of the season, but there were no between-limb differences. From these results, it was determined that (1) the KIPFT is feasible, (2) a minimum of 32 footballers would be required to establish its between-session reliability with ≥80% statistical power and (3) large-cohort normative data for the KIPFT may be best collected at the start of the football season. [ABSTRACT FROM AUTHOR]

Preterm infants are more likely to demonstrate developmental delays than fullterm infants. Postural measurement tools may be effective in measuring the center of pressure (COP) and asymmetry, as well as predicting future motor impairment. The objective of this systematic review was to evaluate existing evidence regarding use of pressure mats or force plates for measuring COP and asymmetry in preterm infants, to determine how measures differ between preterm and fullterm infants and if these tools appropriately predict future motor impairment. The consulted databases included PubMed, Embase, Scopus, and CINAHL. The quality of the literature and the risk of bias were assessed utilizing the ROB2: revised Cochrane risk-of bias tool. Nine manuscripts met the criteria for review. The postural control tools included were FSA UltraThin seat mat, Conformat Pressure-Sensitive mat, Play and Neuro-Developmental Assessment, and standard force plates. Studies demonstrated that all tools were capable of COP assessment in preterm infants and support the association between the observation of reduced postural complexity prior to the observation of midline head control as an indicator of future motor delay. Postural measurement tools provide quick and objective measures of postural control and asymmetry. Based on the degree of impairment, these tools may provide an alternative to standardized assessments that may be taxing to the preterm infant, inaccessible to therapists, or not sensitive enough to capture motor delays. [ABSTRACT FROM AUTHOR]

Balance control can be quantified with measurements from force plates or wearable accelerometers. The purposes of our study were (1) to assess the explanatory power of accelerometer measures to predict center-ofpressure (CoP) sway-area rate across four standing balance tests, (2) to provide expanded Romberg quotient (RQ) reference ranges for older adults, and (3) to perform an agreement analysis between RQs derived from accelerometer measures with those from CoP sway-area rate. Twenty-six healthy older adults completed four 30-s balance tests standing on rigid and foam surfaces with eyes opened and closed on two occasions. Tests were performed on a force plate (1 variable) while wearing accelerometers (5 variables). The outcomes were assessed with linear mixed-effects models, RQs, and agreement analyses. CoP sway-area rate could be significantly predicted by different combinations of accelerometer variables for each balance condition (R²≥0.45). Despite some accelerometer RQs not being significantly different (p≥0.12) from corresponding CoP sway-area rate RQs, there was low agreement between these RQs as determined by intraclass correlation coefficients, Bland-Altman plots, and mountain plots. Clinicians with access to wearable accelerometers but not force plates can use our models to estimate CoP sway-area rate for each standardized test of standing balance. The expanded RQ reference ranges provide information about potential sensory impairments that can influence balance control in older adults. [ABSTRACT FROM AUTHOR]

A force plate is a device that measures the ground reaction force caused by a shift in the human body's center of mass (CoM). Using a controlled change in the human body's CoM, the human body's center of pressure (CoP) is shifted in a 2D plane, along with an acceleration of the CoM along the plane perpendicular to the force plate, which allows for a generation of reference values for game control. In this paper, the development and validation of a system for game control based on a force plate are described. The game control system consists of a force plate, an electronic board used for measuring and PC communication via USB, and a PC application for data acquisition, system calibration, and game control. Based on the measured values of the player's CoP and the CoM acceleration along a plane perpendicular to the force plate, the game control system simulates pressing the UP, DOWN, RIGHT, LEFT, and SPACE keyboard keys or moving the mouse and clicking the left mouse button, which allows players to control simple games. A mathematical model has been developed for the game control system which includes running system calibration procedures in the system for each individual player. The mechatronic game control system is described in detail, and experiments were run on said system for the purpose of system validation. [ABSTRACT FROM AUTHOR]

Abstract Purpose Comprehensive understanding of force plate parameters distinguishing individuals postprimary anterior cruciate ligament reconstruction (ACLR) from healthy controls during countermovement jumps (CMJ) and/or drop jumps (DJ) is lacking. This review addresses this gap by identifying discriminative force plate parameters and examining changes over time in individuals post‐ACLR during CMJ and/or DJ. Methods We conducted a systematic review and meta analyses following the Preferred Reporting Items for Systematic Review and Meta‐Analyses (PRISMA) guidelines. Nine databases were searched from inception to March 2022. We included cross‐sectional papers comparing post‐ACLR with healthy controls or longitudinal studies of individuals at least 6 months postprimary ACLR while performing CMJ and/or DJ on force plates. The methodological quality was appraised using the Modified Downs and Black Checklist. Results Thirty‐three studies including 1185 (50.38%) participants post‐ACLR, and 1167 (49.62%) healthy controls, were included. Data were categorised into single‐leg CMJ, double‐leg CMJ, single‐leg DJ, and double‐leg DJ. Jump height was reduced in both single (mean difference [MD] = −3.13; p

IntroductionWhile using force-plate derived measures of vertical jump performance, reflective of stretch-shortening-cycle (SSC) efficiency is common practice in sport science, there is limited evidence as to which tests and measures may be most sensitive toward neuromuscular fatigue. The aim of this study was to explore the SSC fatigue response to a one-week high-intensity fatiguing phase of training in National Collegiate Athletic Association (NCAA) Division-I basketball players.MethodsThe study timeline consisted of three weeks of baseline measures, one week of high-intensity training, and two weeks of follow-up testing. Countermovement jumps (CMJ) and 10-5 hop tests were performed at baseline, as well as at two time-points during, and three time-points following the fatiguing training period, allowing for performance-comparisons with baseline.ResultsCompared to the weekly training sum at baseline, during the high intensity training phase, athletes were exposed to very large increases in selected external load metrics (ES = 1.44–3.16), suggesting that athletes experienced fatigue acutely, as well as potential longer lasting reductions in performance. Vertical jump data suggested that in the CMJ, traditional metrics such as jump height, as well as metrics reflecting kinetic outputs and movement strategies, were sensitive to the stark increase in high-intensity training exposure. The 10-5 hop test suggested a fatigue-induced loss of tolerance to ground impact reflected by performance reductions in metrics related to jump height and reactive strength qualities.DiscussionThese findings emphasize that when monitoring neuromuscular fatigue, variables and assessments may not be looked at individually, but rather as part of a more global monitoring approach.

Context: Static postural control deficits are commonly documented among individuals with chronic ankle instability (CAI). Evidence suggests individuals with CAI who seek medical attention after an ankle sprain report fewer subjective symptoms. It is unknown if seeking medical attention and receiving supervised physical rehabilitation has a similar effect on objective outcomes, such as static postural control. Objective: To compare measures of single-limb postural control and center of pressure (COP) location between participants with CAI who did or did not self-report attending supervised rehabilitation at the time of their first lateral ankle sprain. Design: Retrospective cohort. Setting: Laboratory. Patients (or Other Participants): Twenty-nine participants with CAI who did (n = 14) or did not (n = 15) self-report attending supervised rehabilitation. Intervention(s): Self-reported attendance or not of supervised rehabilitation at the time of initial injury. Main Outcome Measures: Participants performed three 20-second trials of single-limb stance on a force plate with eyes open. Main outcome measures included the COP velocities, time-to-boundary (TTB) absolute minima, mean of TTB minima, and SD of TTB minima in the anteroposterior and mediolateral directions. The spatial distribution of the COP data points under the foot was quantified within 4 equally proportional sections labeled anteromedial, anterolateral, posteromedial, and posterolateral. Results: Participants who reported attending supervised rehabilitation after their initial ankle sprain had a lower COP velocity in the anterior–posterior direction (P =.030), and higher TTB anterior–posterior absolute minimum (P =.033) and mean minima (P =.050) compared with those who did not attend supervised rehabilitation. Conclusions: Among individuals with CAI, not attending supervised rehabilitation at the time of initial injury may lead to worse static postural control outcomes. Clinicians should continue advocating for patients recovering from an acute ankle sprain to seek medical attention and provide continued care in the form of physical rehabilitation. [ABSTRACT FROM AUTHOR]

Gait initiation (GI) is a functional task classically used in the literature to evaluate the capacity of individuals to maintain postural stability. Postural stability during GI can be evaluated through the “margin of stability” (MoS), a variable that is often computed from force plate recordings. The markerless motion capture system (MLS) is a recent innovative technology based on deep learning that has the potential to compute the MoS. This study tested the agreement between a force plate measurement system (FPS, gold standard) and an MLS to compute the MoS during GI. Healthy adults (young [YH] and elderly [EH]) and Parkinson’s disease patients (PD) performed GI series at spontaneous (SVC) and maximum velocity (MVC) on an FPS while being filmed by a MLS. Descriptive statistics revealed a significant effect of the group (YH vs. EH vs. PD) and velocity condition (SVC vs. MVC) on the MoS but failed to reveal any significant effect of the system (MLS vs. PFS) or interaction between factors. Bland–Altman plot analysis further showed that mean MoS biases were zero in all groups and velocity conditions, while the Bayes factor 01 indicated “moderate evidence” that both systems provided equivalent MoS. Trial-by-trial analysis of Bland–Altman plots, however, revealed that differences of >20% between the two systems did occur. Globally taken, these findings suggest that the two systems are similarly effective in detecting an effect of the group and velocity on the MoS. These findings may have important implications in both clinical and laboratory settings due to the ease of use of the MLS compared to the FPS.

The aim of this paper was to investigate in detail the biomechanics of the knee during different static loadings on the spine using electromyographic (EMG) signals from six main surface muscles acting in the knee joint; three components of the ground reaction force measured by a force plate; knee flexion joint angle measured by a flexible goniometer; and the distances between the bones (femur and tibia) forming the knee joint measured by an echograph. The measurements were taken without weight (reference straight position) and with a weight of 2, 5, 10, 15, 17, and 20 kg placed in a rucksack on the spine. The results showed that the forces in the horizontal and sagittal planes were negligible, and the reaction in the frontal plane increased and was linearly dependent on the carrying weight. The distance between bones decreased linearly with increasing weight for all participants from 3.94% to 53.92% from the referent position. The knee angle varied and in many cases decreased with increasing weight. The calculated correlation coefficients between mean EMG signals and loading weight showed that the adjustment of different subjects’ musculature to increasing load is individual. In general, knee joint balance is a dynamic individual process.

Introduction: Gait initiation is preceded by three anticipatory postural adjustment (APA) phases. In Parkinson's disease (PD) generated force, displacement and timing during APA differ from healthy controls. APA might be influenced by disease status, weight or emotion. It is unknown how motor severity, disease duration or presence of apathy influences APA timing and displacement. Methods: We included 99 people with PD and 50 healthy controls (HC) to perform five gait initiation trials following an auditory cue. Force plates measured timing and center of pressure (CoP) displacement during APA phases. Results: Time to gait initiation (tGI) was higher in the PD group (p

AbstractPostural stability is a crucial aspect of human balance and equilibrium. One way to quantify postural stability is by analyzing variations in the center of pressure under the feet. However, there are several factors involved in quantifying postural stability, and interpreting the information they provide can be challenging, especially in the context of pathological motion. The aim of this work is to reduce the confounding effects of these factors to the extent that measurable differences in results are primarily due to a pathological condition rather than secondary factors such as procedural variations. Materials and methods: The initial research conditions were established based on theoretical aspects of human standing stability. Thirteen normal subjects (5 female and 8 male) with a mean age of 21 ± 4.97 years and a mean BMI of 25.27 ± 4.53 kg/m2 were recruited for the study. Four investigations were conducted, including eyes closed-closed base, eyes open-closed base, eyes closed-open base, and eyes open-open base conditions. Data collection was performed using the AMTI AccuGait force plate and Balance Clinic software. Spectral characteristics, composite multiscale entropy, and conventional stability parameters were computed for both the anterior-posterior (AP) and medial-lateral (ML) directions. Results: Composite multiscale entropy shows no significant difference (p > 0.05) in both AP and medial-lateral (ML) directions. Whereas the frequency of oscillations in ML is more sensitive than other parameters with relatively large effect size (>0.9). Conclusion: The resulting set of variables provides a broad range of options for selecting specific variables related to a particular study topic. The benefit of this method is that it standardizes the analysis of the center of pressure and enables the comparability of variables gathered during various research measurements. For general standing stability measurements, composite multiscale sampling entropy is the most relevant factor that can be used to discriminate the stability state in both the anterior-posterior and medial-lateral directions.

Wearable robots, sometimes known as exoskeletons, are incredible devices for improving human strength, reducing fatigue, and restoring impaired mobility. The control of powered exoskeletons, on the other hand, is still a challenge. This necessitates the development of a technique to simulate exoskeleton–wearer interaction. This study uses a two-dimensional human skeletal model with a powered knee exoskeleton to predict the optimal lifting motion and assistive torque. For lifting motion prediction, an inverse dynamics optimization formulation is utilized. In addition, the electromechanical dynamics of the exoskeleton DC motor are modeled in the lifting optimization formulation. The design variables are human joint angle profiles and exoskeleton motor current profiles. The human joint torque square is minimized subject to physical and lifting task constraints. Then, the lifting optimization problem is solved by the gradient-based sparse nonlinear optimizer (SNOPT). Furthermore, the optimal exoskeleton torque is implemented through a two-phase control strategy to provide optimal assistance in lifting. Experimental validations of the optimal control with 6 Nm and 16 Nm maximum assistive torque are presented. Both 6 Nm and 16 Nm maximum optimal assistance of the exoskeletons reduce the mean values of vastus lateralis, biceps femoris, and latissimus dorsi muscle activations compared to the lifting without the exoskeleton. However, the mean value of the vastus medialis activation is increased by a small amount for the exoskeleton case, although its peak value is reduced. Finally, the experimental results demonstrate that the proposed lifting optimization formulation and control strategy are promising for powered knee exoskeleton for lifting tasks. [ABSTRACT FROM AUTHOR]

A three-dimensional motion capture system (MoCap) and the Garmin Running Dynamics Pod can be utilised to monitor a variety of dynamic parameters during running. The present investigation was designed to examine the validity of these two systems for determining ground contact times while running in place by comparing the values obtained with those provided by the bilateral force plate (gold standard). Eleven subjects completed three 20-s runs in place at self-selected rates, starting slowly, continuing at an intermediate pace, and finishing rapidly. The ground contact times obtained with both systems differed significantly from the gold standard at all three rates, as well as for all the rates combined (p < 0.001 in all cases), with the smallest mean bias at the fastest step rate for both (11.5 ± 14.4 ms for MoCap and −81.5 ± 18.4 ms for Garmin). This algorithm was developed for the determination of ground contact times during normal running and was adapted here for the assessment of running in place by the MoCap, which could be one explanation for its lack of validity. In conclusion, the wearables developed for monitoring normal running cannot be assumed to be suitable for determining ground contact times while running in place. [ABSTRACT FROM AUTHOR]