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This study investigates the determination of the centre of pressure (COP) on spherical sports objects such as cricket balls and footballs using gyroscope data from Inertial Measurement Units (IMUs). Conventional pressure sensors are not suitable for capturing the tangential forces responsible for torque generation. This research presents a novel method to calculate the COP solely from gyroscope data and avoids the complexity of isolating user-induced accelerations from IMU data. The COP is determined from the cross-product of consecutive torque vectors intersecting the surface of the sphere. Effective noise management techniques, including filtering and data interpolation, were employed to improve COP visualisation. Experiments were conducted using a smart cricket ball and a smart football. Validation tests using spin rates between 7.5 and 12 rps and torques ranging from 0.08 to 0.12 Nm confirmed consistent COP clustering around the expected positions. Further analysis extended to various spin bowling deliveries recorded using a smart cricket ball, and a curved football kick recorded using a smart football demonstrated the wide applicability of the method. The COPs of various spin bowling deliveries showed adjacent positions on the surface of the ball, traversing through backspin, sidespin and topspin, excluding the flipper and doosra deliveries. The calculation of the COP on the surface of the soccer ball could only be achieved by increasing the data sampling frequency sevenfold using curve fitting. Knowledge and use of the COP position offers significant advances in understanding and analysing ball dynamics in sports. [ABSTRACT FROM AUTHOR]

The Nike Vaporfly 4% (VP4) shoe is popular due to its unique design and reported performance benefits. However, the underlying mechanisms responsible for the improvements remain unclear. One proposed mechanism is the teeter-totter effect. This study aimed to 1) experimentally test the teeter-totter theory by estimating the teeter-totter moment (MTT) in the VP4 compared to a flat shoe (CONTROL) and 2) quantify the change in the anterior-posterior position of the centre of pressure (Δxa-p) in the VP4 compared to the CONTROL. Plantar pressures and high-speed video were recorded from 15 runners in two shoe conditions. The VP4 generated a larger propulsion moment, MP, ($\mathop \int \nolimits{{\rm{M}}_{\rm{P}}}{\rm{dt}} $ ∫ M P dt = 90.46 ± 38.87 Nms; p < 0.001, d = 1.95), suggesting the presence of an MTT in the VP4 ($\mathop \int \nolimits{{\rm{M}}_{{\rm{TT}}}}{\rm{dt}}$ ∫ M TT dt = 57.16 ± 24.35 Nms) when compared to the CONTROL ($\mathop \int \nolimits{{\rm{M}}_{\rm{P}}}{\rm{dt}}$ ∫ M P dt = 33.30 ± 14.52 Nms). Δxa-p was greater in the VP4 (Δxa-p = 9.48 ± 6.08 mm; p < 0.001, d = 2.07) compared to the CONTROL (Δxa-p = 0.54 ± 0.67 mm). This study provides a methodological proof-of-concept for the teeter-totter theory. The findings highlight the possibility of a teeter-totter effect resulting in greater heel propulsion while running in an AFT shoe construction, assuming a constant muscle moment and pivot point. [ABSTRACT FROM AUTHOR]

Purpose. Forward head posture (FHP) may affect postural stability and balance. This study examines how smartphone texting while balancing, as a dual task, influences the body's centre of pressure (CoP) during single-leg standing in individuals with FHP compared to those with normal posture. Methods. The study utilized a randomized repeated measures design to assess single-leg standing balance and CoP across six conditions. Fifty participants, divided into two groups (25 with FHP and 25 with normal posture), underwent testing sequences involving non-smartphone usage (NU; single task), one-handed smartphone usage (1H; dual task), and two-handed smartphone usage (2H; dual task) on both soft and hard surfaces. Results. The study found that individuals with FHP showed increased CoP sway compared to those with normal posture across all conditions. Both 1H and 2H increased sway compared to non-usage for both groups, with a notable difference in FHP individuals on soft surfaces, where 2H led to greater sway. Conclusions. Individuals with FHP are at a higher risk of balance issues during both NU and smartphone use, particularly during 2H. These results highlight the importance of addressing the impact of FHP on balance control and implementing interventions to reduce associated risks. [ABSTRACT FROM AUTHOR]

Background: Low energy availability (LEA) causes pathophysiology of the female athlete's body affecting the bone and reproductive health and was observed to have a high prevalence in recreational female athletes previously. The aim of this study was to analyse the relationship between low energy availability in females questionnaire (LEAF-Q), bone mineral density (BMD), and postural stability in recreational athletes. Methods: Recreational female athletes (n = 24, age: 23.71 ± 2.94, Tier I) completed LEAF-Q, postural stability measurement during quiet stance (Zebris platform FDM; GmbH) and their BMD was measured using DXA (Hologic QDR Horizon A). Non-parametric statistical tests were used to analyse the relationships between LEAF-Q, BMD, and postural stability and to compare differences between participants divided by the LEAF-Q score and its subscales. Results: Risk of LEA was observed in 50% of recreational athletes participating in this study. Up to 46% of participants perceived menstrual bleeding changes related to training and 37.50% experienced menstrual dysfunction. Body composition and body weight fluctuations were observed to affect postural stability and BMD. With the risk score for LEA, the BMD and postural stability were not negatively affected in recreational athletes. However, the high number of recreational athletes in the risk score for LEA and menstrual dysfunctions highlights the need for public health programs aimed to increase awareness of LEA and its health consequences and for open communication about the menstrual cycle. Future longitudinal studies observing LEA, BMD, menstrual function, postural stability, and their interrelationship in female athletes are needed to increase the knowledge of this topic. [ABSTRACT FROM AUTHOR]

Background: This study aims to investigate the impact of neuromuscular training (NMT) on static and dynamic postural balance (PB) among high‐level male runners with intellectual disability. Method: Twenty‐seven runners were randomly assigned to a NMT group and a control group who maintained their conventional training. Static and dynamic PB were assessed using the centre of pressure (CoP) excursions (in bipedal and unipedal stances under open eyes (OE) and closed eyes (CE) conditions) and the star excursion balance test (SEBT), respectively, at pre‐training and post‐training. Results: The NMT group showed significantly (p < 0.05) decreased CoP values and increased SEBT scores at post‐training compared to pre‐training. The switch from OE to CE did not affect static PB in the bipedal stance, only in the NMT group. Conclusions: The NMT was effective in improving static and dynamic PB in runners with intellectual disability. The NMT could reduce visual dependency. [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]

Conducting applied sport research in real-world settings is challenged by the lack of portable instrumentation capable of producing valid and reliable data that is collected without interfering with the athletes' movement and is meaningful to sport performance. The purpose of this study was to compare and contrast data collected simultaneously from a force platform and a plantar pressure insole to provide support for the use of the XSENSOR® plantar pressure insoles in a skating-performance application. Data was collected in two conditions. The barefoot condition consisted of the insole on a force platform in isolation and the in-skate condition consisted of the insole inside a speed skate boot on a force platform. A single-participant design was conducted whereby an injury-free female completed multiple trials in both conditions. A P6000 Force Platform (BTS Bioengineering Corp., MI, Italy) was used to collect force data and an X4 Foot and Gait Measurement Systems plantar pressure insole (XSENSOR® Technology Corporation, AB, Canada) was used to collect pressure data in the two conditions across four movement patterns; static stance (SS), anterior-posterior sway (AP), medial-lateral sway (ML), and lateral jump (LJ). Intraclass correlation coefficients (ICC) and Bland-Altman plots revealed excellent agreement between the cumulative centre of pressure path length (mm) measured from the force platform and insole in the barefoot condition and moderate to excellent agreement between impulse (Ns) measured from the force platform and insole, in both conditions. These outcomes provide researchers and practitioners with empirical support and confidence to employ the XSENSOR® plantar pressure insoles outside of a laboratory setting in a real-world skating environment to collect and analyse in-skate kinetic data during on ice performance. [ABSTRACT FROM AUTHOR]

Background Low energy availability (LEA) causes pathophysiology of the female athlete’s body affecting the bone and reproductive health and was observed to have a high prevalence in recreational female athletes previously. The aim of this study was to analyse the relationship between low energy availability in females questionnaire (LEAF-Q), bone mineral density (BMD), and postural stability in recreational athletes. Methods Recreational female athletes (n = 24, age: 23.71 ± 2.94, Tier I) completed LEAF-Q, postural stability measurement during quiet stance (Zebris platform FDM; GmbH) and their BMD was measured using DXA (Hologic QDR Horizon A). Non-parametric statistical tests were used to analyse the relationships between LEAF-Q, BMD, and postural stability and to compare differences between participants divided by the LEAF-Q score and its subscales. Results Risk of LEA was observed in 50% of recreational athletes participating in this study. Up to 46% of participants perceived menstrual bleeding changes related to training and 37.50% experienced menstrual dysfunction. Body composition and body weight fluctuations were observed to affect postural stability and BMD. With the risk score for LEA, the BMD and postural stability were not negatively affected in recreational athletes. However, the high number of recreational athletes in the risk score for LEA and menstrual dysfunctions highlights the need for public health programs aimed to increase awareness of LEA and its health consequences and for open communication about the menstrual cycle. Future longitudinal studies observing LEA, BMD, menstrual function, postural stability, and their interrelationship in female athletes are needed to increase the knowledge of this topic.

This study investigates the determination of the centre of pressure (COP) on spherical sports objects such as cricket balls and footballs using gyroscope data from Inertial Measurement Units (IMUs). Conventional pressure sensors are not suitable for capturing the tangential forces responsible for torque generation. This research presents a novel method to calculate the COP solely from gyroscope data and avoids the complexity of isolating user-induced accelerations from IMU data. The COP is determined from the cross-product of consecutive torque vectors intersecting the surface of the sphere. Effective noise management techniques, including filtering and data interpolation, were employed to improve COP visualisation. Experiments were conducted using a smart cricket ball and a smart football. Validation tests using spin rates between 7.5 and 12 rps and torques ranging from 0.08 to 0.12 Nm confirmed consistent COP clustering around the expected positions. Further analysis extended to various spin bowling deliveries recorded using a smart cricket ball, and a curved football kick recorded using a smart football demonstrated the wide applicability of the method. The COPs of various spin bowling deliveries showed adjacent positions on the surface of the ball, traversing through backspin, sidespin and topspin, excluding the flipper and doosra deliveries. The calculation of the COP on the surface of the soccer ball could only be achieved by increasing the data sampling frequency sevenfold using curve fitting. Knowledge and use of the COP position offers significant advances in understanding and analysing ball dynamics in sports.

Compression garments are commonly used during athletic tasks. However, the effect of compression garments on balance, sprinting, jumping and change of direction performance requires further investigation. In the current study, 24 recreationally active participants (12 males, 12 females, age 27 ± 3 years) completed single-leg balance tasks, countermovement jumps, drop jumps, 10 m straight line sprints and change of direction tasks wearing either compression tights (COMP) or regular exercise tights (CON). There was a significant main effect of the condition for 10 m sprint time (p = 0.03, d = -0.18) and change of direction time (p = 0.03, d = -0.20) in favour of COMP. In addition, there was a significant, small difference (p = 0.05, d = -0.30) in ellipse area and a small (p = 0.16, d = 0.21) difference in balance time in favour of COMP during a single-leg balance task. There were no significant differences between trials for any of the other balance or jump tests (p > 0.05). The application of compression tights during exercise may offer small benefits to the performance of balance and change of direction tasks, though these benefits are likely within the typical error of measurement for the tests used. [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 horse's navicular bone is located inside the hoof between the deep flexor tendon (DDFT) and the middle and end phalanges. The aim of this study was to calculate the stress distribution across the articular surface of the navicular bone and to investigate how morphological variations of the navicular bone affect the joint forces and stress distribution. Joint forces normalised to the DDFT force were calculated from force and moment equilibria from morphological parameters determined on mediolateral radiographs. The stress distribution on the articular surface was determined from the moment equilibrium of the stress vectors around the centre of pressure. The ratio of the proximal to the distal moment arms of the DDFT, as well as the proximo-distal position and extent of the navicular bone, individually or in combination, have a decisive influence on the position and magnitude of the joint force and the stress distribution. If the moment arms are equal and the bone is more proximal, the joint force vector originates from the centre of the joint surface and the joint load is evenly distributed. However, in a more distal position with a longer distal moment arm, the joint force is close to the distal edge, where the joint stress reaches its peak. Degenerative navicular disease, which causes lameness and pathological changes in the distal portion of the bone in sport horses, is likely to be more severe in horses with wedge-shaped navicular bones than in horses with square bones. [ABSTRACT FROM AUTHOR]

The Sit-to-Stand (STS) transition is one of the most used activities of daily living and vital for independence. Neurological, or physical injuries impairing functional mobility or sensory feedback often require rehabilitative programs or therapeutic interventions. Understanding the biomechanical elements of daily movements and the interaction between these elements may help inform rehabilitation protocols and optimize targeted interventions, such as stimulation protocols. What are the effects of different initial knee angle, arm facilitation and proprioceptive input on leg muscle activation patterns and balance during and after a sit-to-stand? EMG of four lower limb muscles were recorded in 20 healthy participants as well centre-of-pressure sway amplitude and velocity, as participants stood from a seated position. Initial knee angles were set to various levels of extension (80°, 90°, 100°) and surface stability and arm facilitation were altered using a foam mat or crossing arms. Data were analysed across 3 phases of the STS transition. More extended knee angles resulted in greater mediolateral sway during each phase (p <.01) and had a detrimental effect on anterior-posterior sway in phases 1 and 3. EMG data suggested more extended initial knee angles also increased EMG activity of the Tibialis Anterior (p <.001) and Bicep Femoris (p <.02) within Phases 1 and 2 to assist lift and stabilisation. Findings of this study outline phase-based muscle involvement as well as the compounding effects of reduced proprioceptive input and knee angle, on difficulty of the STS transition. Such results emphasising the need to take sensory and mobility issues into consideration when designing rehabilitative programs or stimulation control systems. • More extended knee angles increase difficulty of STS transition. • Reducing proprioceptive input compounds knee effects. • Mediolateral centre of pressure increases with task difficulty. • Hip extensors and ankle dorsiflexors activate earlier with more extended knee angles. • Phase based analysis provides clearer targets for therapeutic interventions. [ABSTRACT FROM AUTHOR]

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Stroke patients often show postural instability. The patellar tendon reflex is a basic physical examination for stroke patients. This study aimed to explore the correlation between patellar tendon reflex grade and postural stability among stroke patients.

Introduction: Harvesting peroneus longus for ACL reconstruction is thought to create ankle instability which could add to postural instability from an ACL injury. This apprehension prevents its use as a graft of primary choice for many surgeons. To date, there is no evidence available describing changes in postural control after its use in ACL reconstruction. The purpose of the study was to analyse the changes in postural control in the form of static and dynamic body balance after ACL reconstruction with Peroneus Longus Tendon Graft and compare it with the unaffected limb at different time intervals. Materials and methods: Thirty-one participants with ACL injury were selected and subjected to an assessment of static and dynamic balance before and after ACL reconstruction using the HUMAC balance system. Outcome measures for Centre of Pressure (COP) assessment were average velocity, path length, stability score, and time on target. Comparison of scores was done pre-operatively as well as at three- and six-months post-reconstruction with Peroneus longus tendon graft. Results: Static balance of the affected limb showed significant improvement with a decrease in average velocity (F=4.522, p=0.026), path length (F=4.592: p=0.024) and improvement of stability score (F=8.283, p=0.001). Dynamic balance measured by the time on the target variable also showed significant improvement at six-month follow-up (F=10.497: p=0.000). There was no significant difference between the affected and non-affected limb when compared at the different time intervals. Conclusion: The static and dynamic balance, which is impaired after ACL injury, improves with ACL reconstruction with PLT autologous graft. Hence PLTG can be safely used as a graft for ACL reconstruction without affecting postural control and body balance.

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.

Background: Miniature Dachshunds have a high prevalence of neurological and musculoskeletal diseases potentially affecting their balance. The postural stability of dogs in quiet standing is an indicator of postural control and can aid in diagnosing and monitoring lameness and other pathologies affecting balance. Measures of centre of pressure (CoP) can be obtained from force and pressure platform systems to evaluate postural stability, however the two systems have not been compared and the latter has not been validated in dogs. The aims of this study were to assess the validity and reliability of using a pressure mat compared to a force platform and report normative values of CoP measures in healthy miniature Dachshunds. Forty two healthy miniature Dachshunds of smooth, long and wire-haired breed types stood still on a pressure mat (Tekscan MatScan®) placed on a force platform and the two systems were synchronised. Maximum anterior-posterior (AP) and medial-lateral (ML) ranges, sway path and 95% area of a best-fit ellipse were computed. Bland-Altman plots and coefficients of correlation assessed validity; intra-class correlation coefficients (ICC) assessed inter-test reliability for both systems. Non-linear regression analyses were used to describe the relationship between CoP and demographic measures. Results: Strong correlations for AP range, ML range and 95% ellipse area and moderate correlation for sway path were found between the two devices. ICC showed good reliability (0.75–0.90) for AP range and moderate (0.5–0.75) for ML range and the 95% ellipse area for both devices. Sway path reliability was excellent (> 0.90) with the force platform but moderate with the pressure mat. Age was positively correlated with balance (inversely correlated with all measures except sway path), while weight explained 94% (force platform) and 27% (pressure mat) of the variance in sway path. Conclusions: Pressure mats can be used to obtain valid and reliable measures of CoP and replace use of force platforms. Older (non-senior) and heavier (non-obese) dogs show better postural stability. Clinical examinations should include the use of a range of CoP measures when assessing postural balance, while accounting for the effects of age and body weight. [ABSTRACT FROM AUTHOR]

The relationships between movement style and golf performance have been well researched, but the premise of segregated movement styles has not been fully examined. The purpose of this investigation was to examine the postulation that centre of pressure data are not best described by segregated styles but instead by a continuum and to determine relationships between centre of pressure, handicap and clubhead speed using a continuous approach. Centre of pressure paths of driver and 5-iron shots from 104 amateur golfers were analysed using discrete and continuous methods. Discrete methods used different cluster evaluation criteria which result in two-cluster and twenty-cluster solutions being considered "optimum". The two-cluster solution showed the characteristics of "front-foot" and "reverse" centre of pressure styles. However, a continuous principal component analysis method revealed that the clusters were not well separated and provided support for a multidimensional continuum. The principal components had a high correlation with handicap and clubhead speed. Lower handicap and higher swing speed golfers tended to display a centre of pressure with a "front-foot" style and a fast transition towards the front foot at the start of the downswing. A continuous characterisation of centre of pressure styles has more utility than the segregated styles previously described. [ABSTRACT FROM AUTHOR]

The objective of this study was to validate PLATES for assessing unipodal balance in the field, for example, to monitor ankle instabilities in athletes or patients. PLATES is a pair of lightweight, connected force platforms that measure only vertical forces. In 14 healthy women, we measured ground reaction forces during Single Leg Balance and Single Leg Landing tests, first under laboratory conditions (with PLATES and with a 6-DOF reference force platform), then during a second test session in the field (with PLATES). We found that for these simple unipodal balance tests, PLATES was reliable in the laboratory and in the field: PLATES gives results comparable with those of a reference force platform with 6-DOF for the key variables in the tests (i.e., Mean Velocity of the Center of Pressure and Time to Stabilization). We conclude that health professionals, physical trainers, and researchers can use PLATES to conduct Single Leg Balance and Single Leg Landing tests in the laboratory and in the field. [ABSTRACT FROM AUTHOR]

To prevent the risk of stair descent falls and associated injuries in the older adults, it is important to understand the factors that affect this frequent locomotion of daily living. The fact that falls are in most cases the result of the interaction between intrinsic and extrinsic factors is very often underestimated when designing test protocols. Research question: This study aimed at evaluating balance control during and immediately after step down onto an unstable surface. Methods: Physically active men and women aged 60–69 years (n = 28) and 70–79 years (n = 18) were asked to perform a step down onto a foam pad and stand still for 30 s (restabilization phase). Centre of pressure (CoP) velocity and standard deviation of CoP sway in anteroposterior and mediolateral direction were evaluated during the step down (CoP V AP , CoP V ML , CoP SD AP , CoP SD ML) and in the first 5 s of restabilization (CoP V AP5 , CoP V ML5 , CoP SD AP5 , CoP SD ML5). In addition, time to complete step was investigated. Results: Participants aged 70–79 years presented worse ML balance control after step down onto an unstable surface than their younger counterparts. This was represented by the significantly higher values of CoP SD ML5 and CoP V ML5 (p = 0.022 and p = 0.017). No other significant differences were detected. Significance: Age is associated with a more significant ML center of pressure velocity and sway after step down onto a foam pad in physically active older adults. Exercises aimed at improving ML balance control in unstable conditions should be the subject of physical interventions even in older adults with overall good state of health and physical fitness. • Restabilization after step descent is affected by age. • Age affects mediolateral balance control immediately after step descent. • Mediolateral sway and velocity discriminate between two groups of older adults. [ABSTRACT FROM AUTHOR]

We compared two measures of visually induced body sway—head motion and centre of pressure (CoP)—that were simultaneously measured while observing optic flow on a head-mounted display (HMD). Head motion can be conveniently tracked with HMDs, but may have some features different from those of conventional CoP measurements, because of the complex joint structures of the human body. In this analysis, the responses were very similar (except for response gain), and we did not find any significant differences in time or frequency domains. Our results support the use of head motion as a potential predictor of variability in body sway, at least in studies of visually guided postural control. [ABSTRACT FROM AUTHOR]

The rationale of the current article is to investigate hematite suspension based slider bearings of various configurations namely, inclined, secant, exponential, convex and parallel pad stators under the effect of polarization force. The comparative investigation of the load capacity with reference to the position of centre of pressure under varying squeeze and slip conditions has been carried out. The squeeze velocity seems when the upper pad moves normally towards the lower one. The mathematical articulations for non‐dimensional pressure, load capacity and position of the centre of pressure for various configurations of bearing have been acquired. The optimum values of film ratio concerning maximum load capacity for various designed sliders are analyzed at distinct values of squeeze velocity. The interrelation between parallel, inclined and convex pad stator slider bearings is also explored. Finally, a suggestive approach is made to use a particular design of slider under given dynamic conditions. [ABSTRACT FROM AUTHOR]

Background: Low back pain (LBP) is associated with altered postural control, mostly observed at later stages in the LBP trajectory. It is unclear whether postural control differs in the acute phase of LBP.Research Question: Is postural control different in the acute phase of LBP (<2 weeks) and do differences depend on pain intensity, psychological features and/or availability of vision to control posture?Methods: Cross-sectional study design. An unstable sitting paradigm (to reduce the contribution of the legs) assessed postural control of participants with acute LBP (n = 133) and pain-free controls (n = 74). Centre of pressure (CoP) reflected seat movements. Participants balanced with eyes closed, open, or with visual feedback of the anteroposterior CoP position. Balance performance was expressed by CoP displacement and velocity, and stabilogram diffusion analysis. Generalised estimating equations (GEEs) including body mass index, sex, and safety bar touch, tested differences between groups and between balance conditions. Separate GEEs were used to model performance measures and bar touch (yes/no) including pain intensity, disability and psychological features.Results: CoP displacement and critical point coordinates (time and distance where CoP diffusion rate or spread slows) were larger in LBP than pain-free controls independent of balance condition. Long-term diffusion rate was greater in LBP than controls with eyes closed. CoP velocity measures (RMS, short term diffusion rate) were not different between groups. Pain intensity and psychological features were not linearly related to balance performance in participants with acute LBP. Higher pain catastrophizing was associated with touching the safety bar.Significance: Postural control differs in acute LBP than pain-free controls. Findings might be explained by altered sensory processing, lesser ability to reweight proprioceptive information and/or less accurate trunk muscle control. Although not linearly related to pain-intensity or psychological features in the acute stage, reduced balance performance could potentially have impact on LBP recovery. [ABSTRACT FROM AUTHOR]

Background: Diabetic retinopathy is a principal cause of visual damage and blindness, in which laser treatment offers proven therapy. The progressive degeneration of the retina, secondary to diabetes, is believed to cause postural instability although this is not well documented. The aim of this research was to assess how optic flow stimuli contribute to the control of stance in people with impaired retinal functions.Research Question: Does the different retinal functionality correspond to different specific patterns of movements and muscles recruitment?Methods: Postural mechanisms and motor strategies were measured by testing subjects in quiet stance on a force platform with surface electromyography under different optic flow stimulations. Root mean square values of the center of pressure time-varying signals and normalized EMG values were used to evaluate the postural sway.Results: People with diabetic retinopathy, and to a greater extent laser group, were more unstable than healthy subjects. The greater amplitude of the body sway observed in the retinopathy group, and especially in the laser group, could be an expression of the difficulty for this population in processing this kind of visual information.Significance: The increase in muscle activity indicates that there are musculoskeletal and postural changes in the lower limb musculature with increasing severity of diabetic retinopathy. An impaired retinal function might negatively affect postural control in a way that is dependent on the severity of retinal damage. [ABSTRACT FROM AUTHOR]

Purpose: To determine the sensorimotor and clinical function of patients with confirmed successful outcome after either undergoing acromioclavicular joint (ACJ) stabilization, Bankart repair (BR), or rotator cuff repair (RC), and to compare these measures to the contralateral, healthy side without history of previous injuries or surgeries of the upper extremity. It was hypothesized that patients of each interventional group would have inferior sensorimotor function of the shoulder joint compared to the contralateral, healthy side, while presenting with successful clinical and functional outcomes.Methods: Three intervention groups including ten patients who had confirmed successful clinical and functional outcomes after either undergoing ACJ stabilization, BR, or RC were evaluated postoperatively at an average follow-up of 31.7 ± 11.6 months. Additionally, a healthy control group (CG) of ten patients was included. Clinical outcomes were assessed using the Constant-Murley (CM) and American Shoulder and Elbow Surgeons (ASES) Score. Pain was evaluated using the visual analogue scale (VAS). Sensorimotor function was assessed by determining the center of pressure (COP) of the shoulder joint in a one-handed support task in supine position on a validated pressure plate.Results: Each interventional group demonstrated excellent clinical outcome scores including the CM Score (ACJ 83.3 ± 11.8; BR 89.0 ± 10.3; RC 81.4 ± 8.8), ASES Score (ACJ 95.5 ± 7.0; BR 92.5 ± 9.6; RC 96.5 ± 5.2), and VAS (ACJ 0.5 ± 0.9; BR 0.5 ± 0.8; RC 0.5 ± 0.8). Overall, the CG showed no significant side-to-side difference in COP, whereas the ACJ-group and the BR-group demonstrated significantly increased COP compared to the healthy side (ACJ 103 cm vs. 98 cm, p = 0.049; BR: 116 cm vs. 102 cm, p = 0.006). The RC-group revealed no significant side-to-side difference (120 cm vs. 108 cm, n.s.).Conclusion: Centre of pressure measurement detected sensorimotor functional deficits following surgical treatment of the shoulder joint in patients with confirmed successful clinical and functional outcomes. This may indicate that specific postoperative training and rehabilitation protocols should be established for patients who underwent surgery of the upper extremity. These results underline that sensorimotor training should be an important component of postoperative rehabilitation and physiotherapeutic activities to improve postoperative function and joint control.Level Of Evidence: IV. [ABSTRACT FROM AUTHOR]

Postural assessment is an important part of the veterinary evaluation of a dog's neuromusculoskeletal function. It forms an important part of the clinical examination by physiotherapists and specialists in veterinary rehabilitation and sports medicine and is well researched in humans, which has allowed treatment approaches to be developed and validated. This narrative review aims to complement the veterinary literature, which largely quantifies the impact of various conditions on posture, by synthesising the physiotherapy literature, to help translate the use of postural assessment as a basis for the development and validation of treatment techniques to improve outcomes in dogs. • Consideration of posture in dogs is part of physiotherapy assessment and treatment. • Posture is relationship of the segmental regions of the body to each other. • Centre of pressure (COP) is currently the most measured factor of dogs' posture. • Alterations in posture can indicate factors such as pain or weakness. [ABSTRACT FROM AUTHOR]

The objective of this study was to validate PLATES for assessing unipodal balance in the field, for example, to monitor ankle instabilities in athletes or patients. PLATES is a pair of lightweight, connected force platforms that measure only vertical forces. In 14 healthy women, we measured ground reaction forces during Single Leg Balance and Single Leg Landing tests, first under laboratory conditions (with PLATES and with a 6-DOF reference force platform), then during a second test session in the field (with PLATES). We found that for these simple unipodal balance tests, PLATES was reliable in the laboratory and in the field: PLATES gives results comparable with those of a reference force platform with 6-DOF for the key variables in the tests (i.e., Mean Velocity of the Center of Pressure and Time to Stabilization). We conclude that health professionals, physical trainers, and researchers can use PLATES to conduct Single Leg Balance and Single Leg Landing tests in the laboratory and in the field.

In order to improve saddle fit and comfort for the horse, many equestrians use a saddle pad in addition to an ordinary saddle cloth or blanket. To date, only a few scientific studies have investigated if such pads lower the magnitude of pressure exerted on the horse’s back. The results of these studies are highly variable, presumably due to the different materials of the examined pads. The present study investigated the effect of five different, commercially available saddle pads on the mean pressure, the highest mean pressure, and the loaded area below the saddle, as well as the range of motion (ROM) of the centre of pressure (COP) on the horse’s back. Electronic saddle pressure measurements were carried out with eight horses ridden by the same person, using five different pads and a thin saddle cloth as control. Saddle pressure measurements were carried out at all gaits and on both reins, using the Pliance®-S system (Novel). The results revealed that all tested pads except for the gel pad significantly lowered mean pressure below the saddle (range in reduction: 0.8 to 1.8 kPA) as well as in areas with the highest mean pressure, representing pressure points (range: 2.1 to 5.8 kPA). None of the pads increased pressure. The loaded area below the saddle was decreased slightly, but not significantly, when pads were used. The effect of the pads on the ROM of the COP was inconsistent; certain pads significantly increased this variable, but only at certain gaits. This may indicate a loss of stability in the horse-rider system, but if the magnitude of the observed changes is relevant needs further investigation. The results indicate that none of the investigated pads affected mean pressure in an unfavourable way and that the thicker pads may help to reduce the pressure acting on the horse’s back. [ABSTRACT FROM AUTHOR]

To evaluate age and fall-risk related changes in balance ability from measures of bipedal quiet stance, this study aims to investigate the characteristics of 'return to central' - Centre of Pressure (COP) trajectories. COP trajectories were extracted from 60-second COP recordings in bipedal stance. In anterior posterior direction, age was associated with a greater number of detected trajectories, increased velocity and more stringent control. No differences related to fall risk were established or to age or fall risk in mediolateral direction. The characteristics 'return to central' COP trajectories provided insight into the working of the postural control system and can be further developed for application if testing balance under challenging conditions is too risky. [ABSTRACT FROM AUTHOR]

Background: Postural sway during quiet standing has been shown as a useful task to assess risk of falling in older adults. While the risk of falling is consistently reported to be higher in older females than males, the sex-related differences in postural sway are not consistent across the studies.Research Question: What are the effects of age and sex on postural sway during quiet standing during different stance conditions?Methods: We examined the effects of age (40 young and 34 older adults), sex (37 males and 37 females), and their interaction on the postural sway during different stance conditions. We compared the center of pressure (CoP) velocity, amplitude and frequency during parallel (eyes open and eyes closed) and semi-tandem (eyes open) stances.Results: Our results suggest that postural sway is similar between sexes in young participants, while older males exhibit larger postural sway than older female participants (10/21 outcomes). Older female participants exhibited lower CoP amplitude (but larger total and anterior-posterior CoP velocity) compared to young female participants. We also found that the increase in the postural sway with increasing task difficulty is more pronounced in older vs. young adults.Significance: This study shows that ageing-related changes in postural sway are sex- and task-specific. Researchers and clinicians need to be aware of these effects when comparing groups or monitoring changes in time. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine if estimated center of pressure (COP) from plantar force data collected using three-sensor loadsol insoles was comparable to the COP from plantar pressure data collected using pedar insoles during walking and running. Ten healthy adults walked and ran at self-selected speeds on a treadmill while wearing both a loadsol and pedar insole in their right shoe. Plantar force recorded from the loadsol was used to estimate COP along mediolateral (COPx) and anteroposterior (COPy) axes. The estimated COPx and COPy were compared with the COPx and COPy from pedar using limits of agreement and Spearman's rank correlation. There were significant relationships and agreement within 5 mm in COPx and 20 mm in COPy between loadsol and pedar at 20-40% of stance during walking and running. However, loadsol demonstrated biases of 7 mm in COPx and 10 mm in COPy compared to pedar near initial contact and toe-off. [ABSTRACT FROM AUTHOR]

The aim of the study was to examine changes in centre of pressure (COP) movement, alignment and shot outcome during golf shots from flat, uphill, and downhill slopes by mid-handicap golfers. Twelve male golfers hit balls with a six-iron from the flat and 5° slopes while kinematics and kinetics of the swing were collected. A launch monitor measured performance outcomes. A shift in the COP was found during the backswing when playing on a slope, but disappeared during the downswing. Golfers attempted to align the body perpendicular to the slope at the start of the swing resulting in COP movement towards the lower foot, but were not able to maintain this throughout the swing, like low handicap golfers. There was no significant difference in stance width, but golfers placed the ball closer to the uphill foot on a slope. Ball speed was not significantly affected by the slope, but launch angle and ball spin were. Golfers were more likely to hit shots to the left from an uphill slope and to the right for a downhill slope. No consistent compensatory adjustments in alignment at address were found, with differences in final ball position due to lateral spin. [ABSTRACT FROM AUTHOR]

Diabetes and neuropathy have been linked to postural instability. Aims: The purpose of this study is to determine how each system involved in balance is affected when challenged in a static standing posture. The goal was to identify postural instability by measuring balance through the amount of sway and weight bearing distribution in non-neuropathic controlled type II diabetics. Methods: Twelve participants (five males and seven females) with controlled type II diabetes mellitus and no history of peripheral neuropathy (Non-PN cDMII) formed the diabetic group, whereas eighteen participants (7 males and 11 females) without type II diabetes formed the control group. The exclusion criteria was applied via a series of screening tests (Berg Balance Scale, Five Times Sit To Stand Test, Functional Reach Test and Monofilament Test). Postural stability and weight distribution during quiet standing were measured using a Tekscan Matscan pressure mat, which measured the amount of sway and weight distribution. Static postural control was evaluated during eight sensory conditions that perturbed or stimulated the visual, proprioceptive, and vestibular systems. Results: Postural control was found to be significantly deficient when the vestibular system was stimulated, whereas the proprioceptive system was perturbed. After the data analysis, there was a significant difference in antero-posterior sway (p = .05) with the following tasks: eyes open with head movements on an unstable surface, and eyes closed with head movements on a firm surface. Conclusions: The results revealed that the experimental group with type II diabetes had greater postural instability when compared to the control group during tasks with the vestibular system on an unstable surface. This demonstrates that, due to their deficits, individuals with non-PN cDMII are unable to maintain their balance when the vestibular and proprioceptive systems are challenged simultaneously.

The purpose of this study was to determine if estimated center of pressure (COP) from plantar force data collected using three-sensor loadsol insoles was comparable to the COP from plantar pressure data collected using pedar insoles during walking and running. Ten healthy adults walked and ran at self-selected speeds on a treadmill while wearing both a loadsol and pedar insole in their right shoe. Plantar force recorded from the loadsol was used to estimate COP along mediolateral (COPx) and anteroposterior (COPy) axes. The estimated COPx and COPy were compared with the COPx and COPy from pedar using limits of agreement and Spearman’s rank correlation. There were significant relationships and agreement within 5 mm in COPx and 20 mm in COPy between loadsol and pedar at 20–40% of stance during walking and running. However, loadsol demonstrated biases of 7 mm in COPx and 10 mm in COPy compared to pedar near initial contact and toe-off.

Background: Genu valgum results in lower limb malalignment and altered joint mechanics. The study aimed to identify the effects of genu valgum on balance control and muscular work at the joints during gait in children.Research Question: Would bilateral genu valgum affect balance control and muscular work at the joints during gait in children?Methods: Thirteen children with genu valgum and thirteen healthy peers walked at their preferred speed while the body's motions and ground reaction forces were measured to calculate the inclination angles (IA) and the rates of change of IA (RCIA) of the body's center of mass (COM) relative to the center of pressure (COP), as well as the muscular work done at the joints. An independent t-test was used to compare the variables between groups (α = 0.05).Results: Compared to the controls, the patients showed significantly increased step width with altered frontal IA and RCIA variables (p < 0.05), including increased average IA over single-limb support and increased peak RCIA during double-limb support (p < 0.05). The patients significantly increased posterior RCIA at heel-strike but decreased anterior RCIA at toe-off (p < 0.05). The patients showed increased muscular work at both the hip and knee during single-limb support (p < 0.05).Significance: The children with genu valgum showed a specific balance control strategy during gait. In the frontal plane, greater hip and knee muscular work was needed to maintain balance under an increased IA, likely owing to increased step width associated with the valgus alignment. In the sagittal plane, less smooth and less stable COM-COP control with increased RCIA at the key gait events indicates faster weight transfer between double-limb and single-limb support. It is suggested that patients with genu valgum, especially in more severe cases, should be monitored for signs of decreased ability and/or muscular strength in maintaining balance during gait. [ABSTRACT FROM AUTHOR]

Snooker can be an attractive life-long physical activity, given its popularity across all age groups in Asia and Europe. However, scientific research on the cueing movement is limited. This case study presented the biomechanical profiles of the cueing movement in an elite male snooker player (age 37 years old, height 173 cm, body mass 70 kg). Kinematics of the upper limb and cue stick, were examined in five selected snooker tasks (warm-up, stun, top spin, back spin, and stop shots) using the Vicon motion capture system. Ground reaction forces and centre of pressure characteristics were recorded using two Kistler force platforms. Results showed that the cueing movement was contributed primarily by elbow flexion/extension and much less wrist flexion/extension. The high degree of cue stick position overlap between the practice swing and final stroke indicated high level of cueing precision. Weight transfer between feet revealed a slight lean towards the left foot throughout the final stroke, confirming that the elite player was able to maintain high stance stability when executing the cueing movement. Results presented in the present study can serve as a reference for practitioners and scientists to detect error, enhance training, and improve performance in snooker. For practical applications, snooker players are advised to stabilise their shoulder during the cueing movement and deliver the cue stick primarily via elbow movements.

• Novel framework proposed for prosthetic foot design using biomechanics of gait. • Development of finite element model for a priori performance evaluation of foot. • Experimental validation of the model using the structurally complex SACH foot. • Material, geometric and contact nonlinearity included for precise numerical modelling. Performance evaluation of prosthetic feet during their design is typically performed experimentally, which may be time and cost intensive. This work presents a first-of-its-kind application of a numerical procedure for the a priori determination of various stance phase biomechanical parameters of a prosthetic foot, such as its roll-over characteristics, centre of pressure trajectory, ankle flexion moment arm and ankle range of motion, to aid in its design. The numerical procedure is based on finite element analysis, which includes geometric, material and contact non-linearity. Boundary conditions emulating the rocker-based inverted pendulum model were employed to evaluate the biomechanical parameters. The finite element model was validated by employing an inverted pendulum-based apparatus using the structurally complex Ottobock Solid Ankle Cushioned Heel (SACH) prosthetic foot as the test device. A comparison of the numerical and experimental results showed low magnitude of errors. For example, the percentage error of the radius of curvature of the roll-over shape was ~0.1%. The differences found appear to be clinically insignificant, which substantiates the reliability of the model. The proposed numerical model can be employed to obtain detailed a priori insights into the biomechanical parameters influencing a prosthetic foot's characteristics during gait, which can better inform the design, analysis and prescription of prosthetic feet. [ABSTRACT FROM AUTHOR]

The existence of a learning effect by which subjects progressively reduce body sway over the course of repetitive stabilometric measurements is currently debated. Also, the position and orientation of the feet on the platform can have a substantial influence on the outcome measurements. The aim of the present work was to assess the effect of feet positions on mean total velocity (V) of the center of pressure and the area (AR) covered by its displacements during quiet standing. A group of 35 healthy young subjects was examined during two successive sessions consisting of five recordings with their feet placed either in the recommended (standard, SP) or their usual most comfortable (UP) position. Results show a slight decreasing trend that failed to be statistically significant checked with Friedman's ANOVA (SP AR, χ2(4)=6.10, p=0.19 and V, χ²(4)=8.66, p=0.07 and UP AR, χ²(4)=2.32, p=0.68 and V, χ²(4)=1.19, p=0.88). Nonetheless, values of AR and V showed a notable decrement especially evident in the SP exam reaching, respectively, 24% and 11% from baseline, whereas variability measured by the coefficient of variation was the same in the two exams. Given the results, a learning effect should not be ruled out with confidence. Also, usual foot placement would be preferable to avoid this effect. Further research is needed to take into consideration the great variability of stabilometric measurements and the fact that different subjects could adapt more readily to the test conditions than others. [ABSTRACT FROM AUTHOR]

Background: The initiation in human locomotion is defined as the transition between upright stance and steady-state gait. While past literature abundantly investigated the initiation in bipedal gait, the initiation of handstand walking remains unexplored.Research Question: The current study aims to characterise the centre of pressure (CoP) and centre of mass (CoM) trajectory of handstand walking initiation as well as the spatiotemporal and kinematic parameters and balance strategy of this task. Also, the study examined the CoP trajectory similarity within- and between-participants using a coefficient of multiple correlation analysis.Methods: Nineteen gymnasts took part in this study. Handstand walking initiation trials were recorded using force plates and a stereophotogrammetric system. CoM and CoP trajectories were analysed during the Baseline, Preparation and Execution phases of the motor task.Results: We found that to successfully perform the handstand walking initiation, a shift of the CoM forward and towards the stance hand is required as a result of a lateral and posterior CoP shift. All participants performed a similar CoP pattern in the mediolateral direction, whereas two anteroposterior CoP displacement strategies were identified across participants based on different timing execution of posterior CoP shift. While CoP and CoM kinematic differences were identified during the Preparation Phase due to the adopted strategy, no significant difference was found in the Execution Phase for the spatiotemporal and kinematic characteristics.Significance: A better understanding of the required CoP/CoM patterns and balance control provides the basis for further neuromechanics research on the topic and could contribute to individualise training protocols to improve the learning of the task. [ABSTRACT FROM AUTHOR]

• In agriculture, lifting and carrying is one of the most significant contributors toward work-related musculoskeletal disorder. • A novel back-shoulder exoskeleton (HExo) was designed, fabricated, and evaluated for work at orchid house applications. • Joint angle data was used for the design of HExo based on the human motion tracking (HMT) technique. • Using the proposed HExo significantly reduced muscle activation in the back and shoulder region. • Wearing HExo does not affect the user's ability to balance. Work-related musculoskeletal diseases of the lower back and shoulders are frequently caused by lifting, carrying and trunk bending. Therefore, a hybrid exoskeleton (HExo) that provides external torque to the upper extremities and back may reduce discomfort in the lower back and shoulder tendinopathies. In this study, we designed and fabricated HExo, a novel upper-limb and lower-back combined exoskeleton, and evaluated its impact in reducing the musculoskeletal load on the shoulder and back during agricultural work in orchid farms. The human motion tracking technique was utilised to collect the joint angles of orchid farmers during their work, and the joint angle data were subsequently used for the design of HExo. Electromyography (EMG) and centre of pressure (CoP) measurements were taken for 5 participants performing farm tasks and 16 participants performing laboratory-standardised tasks both with and without the HExo. The amplitude probability density function and Wilcoxon signed rank test were utilised in the data analysis to verify the advantage in wearing HExo. The use of HExo resulted in a reduction in erector spinae, latissimus dorsi and anterior deltoid muscle activation of up to 36.92 % (p = 0.05), 31.43 % (p = 0.017), and 57.59 % (p = 0.012), respectively. Furthermore, its use did not affect the ability of participants to maintain balance. Hence, HExo could be a promising for reducing solution musculoskeletal load. [ABSTRACT FROM AUTHOR]

• GVS could be an effective tool for enhancing postural responses in stroke patients. • GVS polarity impacted righting differently in paralyzed & non-paralyzed sides. • Opposing GVS during non-paralyzed side exercise increased movement impact. • Supporting GVS during paralyzed side exercise improved centre of pressure. Patients with post-stroke hemiplegia often exhibit reduced ability to maintain sitting balance, a crucial factor for predicting prognosis. Galvanic vestibular stimulation (GVS) influences postural control by stimulating vestibular organ. Although several studies have focused on GVS in static postures, no studies have demonstrated the influence of GVS on righting reactions. Therefore, we aimed to investigate the effects of GVS on postural righting reactions in seated patients with stroke-induced hemiplegia. Using a vertical board (VB), righting reactions were induced by tilting the VB at 10° after patients sat for 1 min. Patients adjusted their bodies until feeling vertical upon prompt. Twenty-two left hemiplegic patients with cerebrovascular disease participated, divided into two groups undergoing right cathode GVS (RC-GVS) followed by left cathode GVS or vice versa, preceded by sham stimulation. Centre of pressure and the joint angle were measured. During the postural righting reactions towards the paralysed side, RC-GVS enhanced the righting reactions and moved the mean position on the x-axis (COPx) to the right and the mean position on the y-axis (COPy) to the front. During the postural righting reaction towards the right side, RC-GVS induced resistance against the righting reaction, COPx was deflected to the right, COPy was deflected backward, and the angle of the neck tilt increased. The findings revealed that GVS with anodal stimulation on the paralysed side could promote righting reactions in patients with post-stroke hemiplegia. The study findings suggest that using the contralesional placement of the anode promotes righting reactions, and galvanic vestibular stimulation can induce joint movements in the neck and trunk by polarising it to act as resistance against righting reactions. [ABSTRACT FROM AUTHOR]

Abstract Background Approximate entropy (ApEn) and sample entropy (SampEn) have been previously used to quantify the regularity in centre of pressure (COP) time-series in different experimental groups and/or conditions. ApEn and SampEn are very sensitive to their input parameters: m (subseries length), r (tolerance) and N (data length). Yet, the effects of changing those parameters have been scarcely investigated in the analysis of COP time-series. This study aimed to investigate the effects of changing parameters m, r and N on ApEn and SampEn values in COP time-series, as well as the ability of these entropy measures to discriminate between groups. Methods A public dataset of COP time-series was used. ApEn and SampEn were calculated for m = {2, 3, 4, 5}, r = {0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5} and N = {600, 1200} (30 and 60 s, respectively). Subjects were stratified in young adults (age