Characterization of Running Intensity in Canadian Football Based on Tactical Position.

This study aimed to use a data-driven approach to identify individualized speed thresholds to characterize running demands and athlete workload during games and practices in skill and linemen football players. Data were recorded from wearable sensors over 28 sessions from 30 male Canadian varsity football athletes, resulting in a total of 287 performances analyzed, including 137 games and 150 practices, using a global positioning system. Speed zones were identified for each performance by fitting a 5-dimensional Gaussian mixture model (GMM) corresponding to 5 running intensity zones from minimal (zone 1) to maximal (zone 5). Skill players had significantly higher (p < 0.001) speed thresholds, percentage of time spent, and distance covered in maximal intensity zones compared to linemen. The distance covered in game settings was significantly higher (p < 0.001) compared to practices. This study highlighted the use of individualized speed thresholds to determine running intensity and athlete workloads for American and Canadian football athletes, as well as compare running performances between practice and game scenarios. This approach can be used to monitor physical workload in athletes with respect to their tactical positions during practices and games, and to ensure that athletes are adequately trained to meet in-game physical demands.

Mediolateral Postural Control Mechanisms and Proprioception Improve With Kicking Sports Training During Adolescence.

Sensorimotor stimulation during the sensitive period is crucial for proper brain development. Kicking sports (KS) training stimulates these sensorimotor functions. The purpose of this study was to investigate if incorporating specific sensorimotor stimulation in mediolateral axis and proprioceptive inputs during KS training will improve the specific sensorimotor performance in adolescents. We assessed stability limits in 13 KS practitioners and 20 control participants. Starting from an upright position, subjects were asked to lean as far as possible (forward, backward, rightward, and leftward). Three sensory conditions were tested: (1) eyes open, (2) eyes closed, and (3) eyes closed while standing on a foam mat. We analyzed the maximal center of pressure excursion and the root means square of the center of pressure displacements. Results showed that KS group had smaller root means square and larger maximal center of pressure excursions than those of control participants in mediolateral axis in all sensory conditions. Furthermore, the results also revealed a significant smaller root means square excursion in KS group under foam mat condition compared to control group ML axis. This study provides evidence that KS training improved the lateral balance control and proprioceptive integration.

A New Approach to Quantifying Muscular Fatigue Using Wearable EMG Sensors during Surgery: An Ergonomic Case Study.

(1) Background: Surgeons are exposed to musculoskeletal loads that are comparable to those of industrial workers. These stresses are harmful for the joints and muscles and can lead to musculoskeletal disorders (MSD) and working incapacity for surgeons. In this paper, we propose a novel ergonomic and visualization approach to assess muscular fatigue during surgical procedures. (2) Methods: The activity of eight muscles from the shoulder girdle and the cervical/lumbar spines were evaluated using position and electromyographic wearable sensors while a surgeon performed an arthroscopic rotator-cuff surgery on a patient. The time and frequency-domain variables of the root-mean-square amplitude and mean power frequency, respectively, were calculated from an electromyographic signal. (3) Results: The entire surgical procedure lasted 73 min and was divided into 10 sub-phases associated with specific level of muscular activity and fatigue. Most of the muscles showed activity above 60%, while the middle trapezius muscles were almost constantly activated (>20%) throughout the surgical procedure. (4) Conclusion: Wearable sensors can be used during surgical procedure to assess fatigue. Periods of low-to-high activity and fatigue can be evaluated and visualized during surgery. Micro-breaks throughout surgical procedures are suggested to avoid fatigue and to prevent the risk of developing MSD.

Work-related musculoskeletal symptoms amongst Otolaryngologists and Head and Neck surgeons in Canada.

The first objective of this study was to identify work-related musculoskeletal symptoms and determine their prevalence in the practice of Otolaryngology and Head and Neck surgery in Canada. The second objective was to establish potential associations between those musculoskeletal symptoms and variables related to demographic status of the surgeons, their workload and work ergonomics. This study was designed as a Canadian census on work-related musculoskeletal symptoms amongst Otolaryngologist and Head and Neck surgeons. The census was a self-administered electronic survey. It was distributed to all Otolaryngologists and Head and Neck surgeons members of either the Canadian Society of Otolaryngology-Head and Neck Surgery or the Association of Oto-rhinolaryngology-Head and Neck Surgery of Quebec. The questionnaire contained three sections: demographic and workload-related data, identification of work-related musculoskeletal symptoms and evaluation of working ergonomics. The response rate was 23%. Ninety seven percent (97%) of respondents experienced some physical symptom in one or many regions of their body. Seventy-four percents (74%) of respondents noted an exacerbation of their musculoskeletal symptoms by work. Musculoskeletal symptoms limited the daily activities of 45% of respondents while 23% think that their occupational longevity will be diminished by these limitations. The prevalence of work-related musculoskeletal disorders is high among otolaryngologists and its impact on the surgeon's personal and professional life is high. There is a need to improve ergonomics in the clinical and operative room settings and to educate surgeons on ergonomic principles.

Concentrating to avoid falling: interaction between peripheral sensory and central attentional demands during a postural stability limit task in sedentary seniors.

Evidence suggests falls and postural instabilities among seniors are attributed to a decline in both the processing of afferent signals (e.g., proprioceptive, vestibular) and attentional resources. We investigated the interaction between the non-visual and attentional demands of postural control in sedentary seniors. Old and young adults performed a postural stability limit task involving a maximal voluntary leaning movement with and without vision as well as a cognitive-attentional subtraction task. These tasks were performed alone (single-task) or simultaneously (dual-task) to vary the sensory-attentional demands. The functional limits of stability were quantified as the maximum center of pressure excursion during voluntary leaning. Seniors showed significantly smaller limits of postural stability compared to young adults in all sensory-attentional conditions. However, surprisingly, both groups of subjects reduced their stability limits by a similar amount when vision was removed. Furthermore, they similarly decreased their anterior-posterior stability limits when concurrently performing the postural and the cognitive-attentional tasks with vision. The overall average cognitive performance of young adults was higher than seniors and was only slightly affected during dual-tasking. In contrast, older adults markedly degraded their cognitive performance from the single- to the dual-task situations, especially when vision was unavailable. Thus, their dual-task costs were higher than those of young adults and increased in the eyes-closed condition, when postural control relied more heavily on non-visual sensory signals. Our findings provide the first evidence that as posture approaches its stability limits, sedentary seniors allot increasingly large cognitive attentional resources to process critical sensory inputs.

A kinematic analysis of jumping technique in elite Korean teeterboard athletes: a case-study.

Korean teeterboard is a circus discipline that consists of a board pivoted at its centre upon which two acrobats are catapulted in turn performing acrobatic jumps. This paper presents one of the first studies that focuses on investigating the factors that contribute to jump height in Korean teeterboard. A total of 120 jumps were recorded from two acrobats using motion capture. Selected variables were input to a Boosted Regression Trees (BRT) analysis, corresponding to three specific events: acrobat landing, rotation of the teeterboard and acrobat take-off. Significant predictor variables were identified as: 1) body's centre of mass vertical velocity at the first contact with the teeterboard (relative importance: 69.4%) for landing, 2) maximum downward vertical teeterboard velocity for teeterboard rotation (72.7%) and 3) maximum upward vertical teeterboard velocity for take-off (50.4%). Kinematic parameters such as hip range of motion during take-off also contributed significantly to jump height (37.2%). The results provide understanding of the complex kinematics between two acrobats and a flexible pivoting board. Teeterboard designers, acrobats and trainers should be aware that maximising these parameters are the best strategies to improve jump height.

How Can Biomechanics Improve Physical Preparation and Performance in Paralympic Athletes? A Narrative Review.

Recent research in Paralympic biomechanics has offered opportunities for coaches, athletes, and sports practitioners to optimize training and performance, and recent systematic reviews have served to summarize the state of the evidence connecting biomechanics to Paralympic performance. This narrative review serves to provide a comprehensive and critical evaluation of the evidence related to biomechanics and Paralympic performance published since 2016. The main themes within this review focus on sport-specific body posture: the standing, sitting, and horizontal positions of current summer Paralympic sports. For standing sports, sprint and jump mechanics were assessed in athletes with cerebral palsy and in lower-limb amputee athletes using running-specific prostheses. Our findings suggest that running and jumping-specific prostheses should be 'tuned' to each athlete depending on specific event demands to optimize performance. Standing sports were also inclusive to athletes with visual impairments. Sitting sports comprise of athletes performing on a bike, in a wheelchair (WC), or in a boat. WC configuration is deemed an important consideration for injury prevention, mobility, and performance. Other sitting sports like hand-cycling, rowing, and canoeing/kayaking should focus on specific sitting positions (e.g., arm-crank position, grip, or seat configuration) and ways to reduce aero/hydrodynamic drag. Para-swimming practitioners should consider athlete-specific impairments, including asymmetrical anthropometrics, on the swim-start and free-swim velocities, with special considerations for drag factors. Taken together, we provide practitioners working in Paralympic sport with specific considerations on disability and event-specific training modalities and equipment configurations to optimize performance from a biomechanical perspective.

Learned Overweight Internal Model Can Be Activated to Maintain Equilibrium When Tactile Cues Are Uncertain: Evidence From Cortical and Behavioral Approaches.

Human adaptive behavior in sensorimotor control is aimed to increase the confidence in feedforward mechanisms when sensory afferents are uncertain. It is thought that these feedforward mechanisms rely on predictions from internal models. We investigate whether the brain uses an internal model of physical laws (gravitational and inertial forces) to help estimate body equilibrium when tactile inputs from the foot sole are depressed by carrying extra weight. As direct experimental evidence for such a model is limited, we used Judoka athletes thought to have built up internal models of external loads (i.e., opponent weight management) as compared with Non-Athlete participants and Dancers (highly skilled in balance control). Using electroencephalography, we first (experiment 1) tested the hypothesis that the influence of tactile inputs was amplified by descending cortical efferent signals. We compared the amplitude of P1N1 somatosensory cortical potential evoked by electrical stimulation of the foot sole in participants standing still with their eyes closed. We showed smaller P1N1 amplitudes in the Load compared to No Load conditions in both Non-Athletes and Dancers. This decrease neural response to tactile stimulation was associated with greater postural oscillations. By contrast in the Judoka's group, the neural early response to tactile stimulation was unregulated in the Load condition. This suggests that the brain can selectively increase the functional gain of sensory inputs, during challenging equilibrium tasks when tactile inputs were mechanically depressed by wearing a weighted vest. In Judokas, the activation of regions such as the right posterior inferior parietal cortex (PPC) as early as the P1N1 is likely the source of the neural responses being maintained similar in both Load and No Load conditions. An overweight internal model stored in the right PPC known to be involved in maintaining a coherent representation of one's body in space can optimize predictive mechanisms in situations with high balance constraints (Experiment 2). This hypothesis has been confirmed by showing that postural reaction evoked by a translation of the support surface on which participants were standing wearing extra-weight was improved in Judokas.

The John Charnley Award: The functional outcome of hip resurfacing and large-head THA is the same: a randomized, double-blind study.

UNLABELLED: Better functional outcome is believed by some to occur after hip resurfacing (HR) than conventional 28-mm total hip arthroplasty (THA) in young and active patients with hip osteoarthritis. However, the postulated superior outcome of HR over THA may simply be the result of a bias in patient selection or the use of a larger femoral head. We therefore asked whether HR would demonstrate superior functional outcome when compared with a THA with a large-diameter femoral head in a randomized, double-blind study. Gait speed and postural balance evaluations, functional tests, and clinical data were analyzed preoperatively and at 3, 6, and 12 months after surgery. Gait speed was used as the primary outcome measure. Forty-eight patients were randomized in the study and a third group of 14 healthy subjects served as controls. The gait speed and postural balance evaluations, the performance at most functional tests, and clinical scores were similar in HR and large-head THA groups at each followup period. The operated patients reached most control group values at 3 months postoperatively. By these measures, HR did not provide better clinical function over large-head THA. LEVEL OF EVIDENCE: Level I, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Gait patterns after total hip arthroplasty and surface replacement arthroplasty.

OBJECTIVE: To compare gait patterns in patients with total hip arthroplasty (THA) and surface hip arthroplasty. DESIGN: Observational study. SETTING: Outpatient biomechanical laboratory. PARTICIPANTS: Two groups of 10 surface hip arthroplasty and THA patients and 10 control subjects participated in the study (N=30). The patients were volunteers recruited from a larger randomized study. INTERVENTIONS: Not applicable. MAIN OUTCOMES MEASURES: Gait patterns, hip abductor muscle strength, clinical outcomes, and radiographic analyses were compared between groups. RESULTS: In the sagittal plane, the THA group showed a larger flexor moment and larger mechanical work in H2S and K3S power bursts compared with surface hip arthroplasty and control subjects. In the frontal plane, both THA and surface hip arthroplasty patients had smaller hip abductor muscles energy generation (H3F) than the control group. No difference was found for the hip abductor muscles strength. CONCLUSIONS: In the THA group, the larger energy absorption in H2S and K3S would be a cost-effective mechanical adaptation to increase stability. The surface hip arthroplasty characteristics could allow the return to a more normative gait pattern compared with THA. The modification in the frontal plane in surface hip arthroplasty and THA would be related to the hip abductor muscles strength.

Postural balance during quiet standing in patients with total hip arthroplasty with large diameter femoral head and surface replacement arthroplasty.

OBJECTIVE: To compare postural balance between patients who have had either a large diameter head total hip arthroplasty or surface replacement arthroplasty. DESIGN: Observational study. SETTING: Outpatient biomechanical laboratory. PARTICIPANTS: Two groups of 14 patients with surface replacement or large diameter head total hip arthroplasties recruited from a larger randomized study and 14 control subjects. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Postural balance during quiet standing in dual and one-leg stance (operated leg), hip abductor muscle strength, clinical outcomes, and radiographic analyses were compared between groups. RESULTS: Compared to the control group, patients in both groups showed smaller center of pressure displacement amplitude in the medial-lateral direction in dual stance. Patients with large diameter head total hip arthroplasty showed lower hip abductor muscle strength compared to control subjects. There was statistical difference between the 2 patient groups in biomechanical reconstruction of the hip. Despite these differences, there was no significant difference in the ability to complete the one-leg stance task between the 3 groups. CONCLUSIONS: The muscular strength in the operated limb could be mainly responsible for the lower center of pressure displacement amplitude compared to control subjects. However, the ability to complete the one-leg stance demonstrates that patients do not fear to load the hip prosthesis when needed. The large diameter femoral head may be a major mechanical factor contributing to these results.

Development of postural stability limits: Anteroposterior and mediolateral postural adjustment mechanisms do not follow the same maturation process.

There is increasing evidence that indicates a critical transition period for the maturation of postural control from the ages of 6-7 years. Some studies suggest that this transitional period may be explained by a change from a ballistic toward a sensory strategy, but the cause remains unknown. The purpose of this study was to investigate the influence of the transition period on dynamic postural control in a natural self-initiated leaning task under different sensory conditions. We evaluated the center of pressure (COP) displacement during maximum leaning in four directions (forward, backward, rightward, leftward) under three sensory conditions (eyes open, eyes closed and eyes closed standing on a foam). Three groups were tested: young children (4 years old), older children (8-10 years old) and adults (21-42 years old). The maximum COP excursion along the anteroposterior and mediolateral axes and the COP amplitude were analyzed. Young children showed smaller maximum anteroposterior and mediolateral COP excursion than other groups. Older children also exhibited a significantly smaller maximum excursion along the mediolateral direction but performed similar to adults along the anteroposterior direction. In a similar manner, the analysis of the COP amplitude did not indicate any differences between the groups along the anteroposterior axis. In contrast, along the mediolateral axis, the results showed developmental differences. Furthermore, the effect of sensory conditions was similar across the children's groups. Our results suggest an important plasticity period for the maturation of postural control mechanisms. Notably, our findings support the idea that the postural mechanisms controlling the anteroposterior axis reach maturity before the mechanisms involved in controlling the mediolateral axis.

The control of upright stance in young, elderly and persons with Parkinson's disease.

The aims of the present study are twofold: (1) to compare the postural control mechanisms of young and elderly people as well as in Parkinson's disease (PD) patients during quiet standing and (2) to assess the impact of a stooped posture on these mechanisms. All subjects were required to maintain both a side-by-side and a 45 degrees foot position. Elderly subjects performed a third condition where they were requested to mimic the stooped posture as adopted by PD subjects. The net centre of pressure (COP(net)) and centre of mass (COM) profiles in the anterior/posterior (A/P) and medial/lateral (M/L) planes were analyzed. The COP(net) signal was recorded from two force plates and was categorized in two mechanisms: an ankle mechanism (COP(c)) and a load/unload hip mechanism (COP(v)). The results showed similar postural control mechanisms in young, elderly and PD subjects. When the feet were side-by-side, the COP(net) was controlled by the ankle plantar/dorsiflexors (COP(c)) in the A/P direction, while by the hip abductor/adductors (COP(v)) controlled in the M/L direction. When the feet were in the 45 degrees position, both the ankle and hip mechanisms contributed to the COP(net). However, the PD subjects showed significant smaller RMS amplitudes compared to the elderly people in the 45 degrees foot position and in the stooped posture. These findings suggest that PD subjects resort to a stiffening strategy to control their balance in postural tasks that imply a mixed control (ankle and hip mechanisms) but have adapted to their stooped posture.

Estimation of the centre of mass for the study of postural control in Idiopathic Scoliosis patients: a comparison of two techniques.

The objective of the present study is to quantify the position of the Centre of Mass (COM) during quiet standing using a force plate and compare this technique to the quantification of the COM with an anthropometric model. The postural control of 18 healthy adolescents and 22 IS patients was evaluated using an Optotrak 3D kinematic system, and two AMTI force plates during quiet standing. The position of anatomical landmarks tracked by the Optotrak system served to estimate the position of the COM of both groups using an anthropometric model (COM(anth)). The force plate served to estimate the position of the COM through double integration of the horizontal ground reaction forces (COM(gl)). The mean position and root mean square (RMS) amplitude of COM(gl, )in reference to the base of support (BOS) and the first sacral prominence (S1) were quantified in the Anterior-Posterior (A/P) and Medial-Lateral (M/L) directions. There was a significant difference between the control subjects and IS patients for the displacement of the COM(gl) in reference to the BOS in both the A/P and M/L directions. There was no difference between groups for the mean position of the COM(gl), however, 63% of the IS and 43% of the controls had a lateral position of the COM(gl )in reference to S1 of greater than 5 mm. There was a significant difference between groups in the A/P and M/L directions for the amplitude of error between the COM(gl) and COM(anth) techniques.

Postural balance during quiet standing in patients with total hip arthroplasty and surface replacement arthroplasty.

BACKGROUND: Primary total hip arthroplasty leads to better functional capacities but a general weakness of abductor muscles often persists. A larger head component may improve the postural balance in the medial-lateral direction. The aims of this study are (1) to compare postural stability in patients after total hip and surface replacement arthroplasties and (2) to evaluate the effect of the biomechanical reconstruction on postural stability. METHODS: Six months post-surgery, three groups of ten subjects (total hip and surface replacement arthroplasties and control) performed quiet standing tasks in both dual and one leg stance and a hip abductor muscles strength test. The root-mean-square amplitude of centre of pressure and centre of mass displacement in the anterior-posterior and medial-lateral directions were calculated for dual stance task. FINDINGS: Statistical analyses showed greater centre of pressure and centre of mass displacement amplitude in the medial-lateral direction during the dual stance for the total hip arthroplasty compared to the surface replacement and control subjects (P<0.05). All control subjects completed the one leg stance compared to nine in the surface replacement and five in the total hip arthroplasty group. No statistical difference was found between the groups in the hip abductor muscles strength. INTERPRETATION: The better anatomical preservation, absence of femoral stem and the larger bearing component could account for the return to better postural stability in surface replacement patients in comparison to total hip patients. Further studies are needed to determine the impact of each of these factors on the postural balance.

Kinematic and kinetic analysis of a stepping-in-place task in below-knee amputee children compared to able-bodied children.

It has been demonstrated that below-knee amputee (BKA) subjects use specific compensation strategies to overcome their physical limitations. Biomechanical studies emphasize that the motor strategies adopted by BKA adults differ between their amputated limb and their nonamputated limb and from those employed by able-bodied (AB) subjects. The purpose of this investigation was to compare the motor solutions used by control AB and BKA children during a stepping-in-place (SIP) task and to assess how they regulate the coordination of their nonamputated and amputated limbs during this task. Eight BKA children and eight AB children paired for gender, age, weight and height participated in our study. One-way analysis of variances (ANOVAs) were performed on peaks of angular excursion, moment, and power at the hip, knee, and ankle to compare motor strategies between the BKA and AB groups. The main results of our experiment showed that even if BKA and AB children did the task with almost the same kinematics, the kinetic data revealed completely different mechanisms of the two groups to achieve the SIP task, and BKA children had a symmetrical interlimb strategy. SIP, a simple task compared to gait at the level of neuro-musculoskeletal demands, could thus offer a transition task to physical therapists for below-knee recently-amputated children.

Double-Blind, Placebo-Controlled, Randomized Phase I/IIa Study (Safety and Efficacy) with Buspirone/Levodopa/Carbidopa (SpinalonTM) in Subjects with Complete AIS A or Motor-Complete AIS B Spinal Cord Injury.

BACKGROUND: No drug treatment capable of restoring locomotor capabilities in patients suffering a motor-complete spinal cord injury (SCI) has ever been developed. We assessed the safety and efficacy of an activator of spinal locomotor neurons in humans, which were shown in paraplegic animals to elicit temporary episodes of involuntary walking. METHODS: Single administration of buspirone/levodopa/carbidopa (SpinalonTM), levodopa/carbidopa (ratio 4: 1), and buspirone or placebo was performed using a dose-escalation design in 45 subjects placed in supine position who had had an SCI classified as complete (AIS A) or motor-complete/sensory incomplete (AIS B) for at least 3 months. Blood samples before and at regular intervals (15, 30, 60, 120, 240 min) after treatment were collected for hematological and pharmacokinetic (PK) analyses. Electromyographic (EMG) activity of eight muscles (four per leg) was monitored prior to and at several time points after drug administration. RESULTS: SpinalonTM (10-35 mg buspirone/100-350 mg levodopa/25-85 mg carbidopa) displayed no sign of safety concerns - only mild nausea was found in 3 cases. At higher doses, 50 mg/500 mg/125 mg SpinalonTM was considered to have reached maximum tolerated dose (MTD) since 3 out of 4 subjects experienced related adverse events including vomiting. PK analyses showed comparable data between groups suggesting no significant drugdrug interaction with SpinalonTM. Only the SpinalonTM-treated groups displayed significant EMG activity accompanied by locomotor-like characteristics - that is with rhythmic and bilaterally alternating bursts. CONCLUSION: Therefore, this study provides evidence of safety and preliminary efficacy following a single administration of SpinalonTM in subjects with SCI.

Inter-segmental coordination: motor pattern in humans stepping over an obstacle with mechanical ankle joint friction.

This study examined the influence of a mechanical perturbation of the ankle joint on obstacle avoidance pattern. A decoupled control between the distal joint and the combined (hip-knee) proximal joints was observed according to the task requirement. In this context, a greater mechanical friction at the ankle should be compensated at this joint (local compensation) or alternatively, by regulating more combined proximal joints (knee and/or hip). The leading limb inter-segmental coordination was evaluated in both no constraint and constraint conditions in calculating ranges of motion (ROM), moments of force and powers (from heel-off to obstacle) at the ankle, knee and hip joints. Electromyographic activities were also analyzed. With the constraint, the dorsiflexor moment and the tibialis anterior activity remained unchanged while both ROM and power bursts (absorbed and generated) decreased. The hip and knee ROM remain invariant. At heel-off the absorption by hip extensors decreased and the forthcoming generation by knee flexors increased in the constraint condition. To quantify the inter-joint coordination, principal component analysis was used and indicated a high level of inter-joint coupling (synergy) that decreased with the constraint (i.e. less inter-joint coupling). At the ankle joint, the results suggest that the central command was the same in both conditions thus, not be adapted. At both the hip and knee joints, a combined joints modulation occurred to overcome additional friction.

Evaluation of segmental postural characteristics during quiet standing in control and Idiopathic Scoliosis patients.

BACKGROUND: The complex skeletal deformations that accompany Idioapthic Scoliosis pose a challenge to the clinician to non-invasively discriminate Idiopathic Scoliosis patients from children with no pathology. Therefore, the focus of this study is to non-invasively evaluate the position and amplitude of displacement of the pelvis, shoulders and thorax during quiet standing of Idiopathic Scoliosis patients and control subjects. METHODS: The quiet standing posture of 18 healthy adolescent females and 22 Idiopathic Scoliosis subjects was evaluated using an Optotrak 3020 position sensor over a period of 120 s, with 4 repeat trials. Outcome measures included the mean position, root mean square amplitude and range over the duration of 120 s trials for both linear and angular measures of the pelvis, thorax and shoulders. Appropriate sample times were chosen and evaluated for stability over the 120 s period, and between trial reliability was evaluated. FINDINGS: There was a significant difference between groups for the mean position of the shoulder blade rotation in reference to the base of support and to the pelvis. The Idiopathic Scoliosis patients had a significantly larger root mean square amplitude of anterior-posterior displacement of the T1 and S1 spinous processes in reference to the base of support. There was no difference between the sample durations to estimate the mean position of the body segments, however the root mean square increased significantly. INTERPRETATION: This study demonstrates that postural abnormalities are evident during quiet standing in Idiopathic Scoliosis patients.

Postural control mechanisms during quiet standing in patients with diabetic sensory neuropathy.

OBJECTIVE: The objective of the present study was to compare postural mechanisms identified by using dual force platform in healthy elderly community-dwelling subjects and diabetic sensory neuropathy (DSN) patients under different visual conditions. RESEARCH DESIGN AND METHODS: The presence and the severity of the sensory neuropathy was evaluated with a clinical scale. Postural mechanisms and motor strategies of the ankle and hip joints were quantified by testing subjects in quiet stance on a dual force platform under two visual conditions (eyes open and eyes closed). Root mean square (RMS) values of the center of pressure (COP) time-varying signals and normalized cross-correlation function were used to estimate the contribution and the interdependence of postural control mechanisms. RESULTS: DSN patients show larger RMS values of the COP(net) displacement in both anteroposterior and mediolateral (ML) directions. Motor strategies at the ankle joints are altered in DSN patients compared with healthy elderly subjects particularly in the ML direction. CONCLUSIONS: This experiment is the first to highlight that even with vision, postural mechanisms at the ankle joints are impaired in DSN patients during quiet standing. Our results point out the importance of focusing on postural control instability in ML of DSN patients.