Spinal posture changes using dynamic rasterstereography during the modified Matthiass test discriminate between postural weak and strong healthy children (10-14 years): a pilot study.

The aim of this pilot study was to investigate whether the clinical Matthiass test can be objectified by means of dynamic rasterstereography in children. We aimed at discriminating between postural weak and strong children. Dynamic rasterstereography was used to capture sagittal spinal posture changes during the modified Matthiass test (mMT). Primary outcomes were spinal posture changes (trunk inclination, kyphotic and lordotic angles) during the test. Two-step cluster analysis was run jointly on the three primary outcomes. Data of 101 healthy children (10-14 years, 46% girls) were assessed. Cluster analysis identified two groups of participants with significantly different postural performance levels during the mMT (low vs. high performers). Low performers showed a higher increase in backward lean, as well as kyphosis and lordosis (4°-5°, respectively) when compared to high performers. The two performance groups were age-, BMI-, and activity-matched.Conclusion: This pilot study established preliminary normative data on spinal posture changes during the Matthiass test (high performers) and provided corresponding cutoff values for postural weakness (low performers). These results could provide a basis for future longitudinal and interventional studies targeting long-term consequences of childhood postural weakness and the prevention of back pain. What is Known: • The prevalence of postural insufficiencies in children is high. • No consensus exists about the postural assessment in children. • A common clinical test to identify postural insufficiency is the Matthiass test yet criticized for its subjective assessment. What is New: • This pilot study objectified the modified Matthiass test by rasterstereography and statistically identified two groups of healthy children with different postural performance levels. • It established preliminary normative data on spinal posture changes and provided corresponding cutoff values for postural weakness.

Spinal postural changes during the modified Matthiass test in healthy children : Interday and interrater reliability of dynamic rasterstereographic measurements.

OBJECTIVE: The Matthiass test serves to identify postural insufficiencies by evaluating the sagittal posture but this subjective assessment may be responsible for different reports on the prevalence of postural insufficiencies in children. Previously, rasterstereography was used to objectify this clinical test. Until now, the coupling of the Matthiass test with rasterstereography has not yet been applied to children and the reliability is unknown; therefore, the objective of our study was to provide interday and interrater reliability of rasterstereographic measurements during dynamic (modified Matthiass test) and static trials (only interday) in healthy children. METHODS: Trunk inclination, kyphotic, and lordotic angles were measured using rasterstereography during static and dynamic trials (modified Matthiass test: 90° shoulder flexion, hand-held load, 5% of body weight). Intraclass correlation coefficients (ICC) were calculated using a two-way mixed model (absolute agreement, average measure). RESULTS: In this study 21 healthy children were assessed (age range 10-12 years). Dynamic rasterstereographic measurements showed fair to good interday and interrater reliability (ICC 0.46-0.70) and static measurements good to excellent interday reliability (ICC 0.63-0.91). CONCLUSION: Dynamic rasterstereography during the modified Matthiass test furnishes reliable data serving to objectify spinal changes of healthy children and detect postural insufficiencies. Additional efforts are needed to investigate how the early detection of postural insufficiencies can help to prevent back pain in children, adolescents and adults.

Effect of haptic supplementation provided by a fixed or mobile stick on postural stabilization in elderly people.

BACKGROUND: Haptic supplementation by a light touch with the index finger on a stable surface has been widely shown to increase postural stability. With a view to a potential application in the domain of mobility aids, it should, however, be demonstrated that haptic supplementation is effective even if provided by a mobile support. OBJECTIVE: The present experiment aimed at determining whether haptic supplementation was effective in elderly people when provided by a light grip on an unstable stick support. METHODS: Ten young and 11 older adults were tested in an upright position in 6 experimental conditions, in which the mobility of the stick support and its resistance to body sway were manipulated. Classical center-of-pressure (COP) variables (i.e. root mean square variability, range and area) were computed together with power spectral analysis and stabilogram diffusion analysis (SDA) variables of COP. RESULTS: The results suggest that the stabilizing effect of haptic supplementation is independent of age and the nature of the support (fixed or mobile) when transient sway-related contact forces at the fingertip and proprioceptive cues are of sufficient magnitude. The results also indicate that haptic supplementation attenuates the age-related increase in energy consumption during the postural task even in the mobile support condition on a low-resistance surface. The results of SDA suggest that the availability of sway-related haptic cues reduces reliance on increased muscle activity around the ankle over short time intervals of postural control. After some time, haptic supplementation eventually leads to well-coordinated postural corrections. CONCLUSIONS: In summary, haptic supplementation improves postural control mechanisms independent of age due to enhanced perception of self-motion through sensory interaction with the environment.

Agonist and antagonist activation at the ankle monitored along the swing phase in hemiparetic gait.

BACKGROUND: Descending command in hemiparesis is reduced to agonists and misdirected to antagonists. We monitored agonist and antagonist activation along the swing phase of gait, comparing paretic and non-paretic legs. METHODS: Forty-two adults with chronic hemiparesis underwent gait analysis with bilateral EMG from tibialis anterior, soleus and gastrocnemius medialis. We monitored ankle and knee positions, and coefficients of agonist activation in tibialis anterior and of antagonist activation in soleus and gastrocnemius medialis over the three thirds of swing phase. These coefficients were defined as the ratio of the root-mean-square EMG from one muscle over any period to the root-mean-square EMG from the same muscle over 100 ms of its maximal voluntary isometric contraction. FINDINGS: As against the non-paretic side, the paretic side showed lesser ankle dorsiflexion and knee flexion (P < 1.E-5), with higher coefficients of agonist activation in tibialis anterior (+100 ± 28%, P < 0.05), and of antagonist activation in soleus (+224 ± 41%, P < 0.05) and gastrocnemius medialis (+276 ± 49%, P < 0.05). On the paretic side, coefficient of agonist activation in tibialis anterior decreased from mid-swing on; coefficients of antagonist activation in soleus and gastrocnemius medialis increased and ankle dorsiflexion decreased in late swing (P < 0.05). INTERPRETATION: During the swing phase in hemiparesis, normalized tibialis anterior recruitment is higher on the paretic than on the non-paretic leg, failing to compensate for a marked increase in plantar flexor activation (cocontraction). The situation deteriorates along swing with a decrease in tibialis anterior recruitment in parallel with an increase in plantar flexor activation, both likely related to gastrocnemius stretch during knee re-extension. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT03119948.

Arch index and running biomechanics in children aged 10-14 years.

BACKGROUND: While altered foot arch characteristics (high or low) are frequently assumed to influence lower limb biomechanics and are suspected to be a contributing factor for injuries, the association between arch characteristics and lower limb running biomechanics in children is unclear. RESEARCH QUESTION: Therefore, the aim of this study was to investigate the relationship between a dynamically measured arch index and running biomechanics in healthy children. METHODS: One hundred and one children aged 10-14 years were included in this study and underwent a biomechanical investigation. Plantar distribution (Novel, Emed) was used to determine the dynamic arch index and 3D motion capture (Vicon) to measure running biomechanics. Linear mixed models were established to determine the association between dynamic arch index and foot strike patterns, running kinematics, kinetics and temporal-spatial outcomes. RESULTS: No association was found between dynamic arch index and rate of rearfoot strikes (p = 0.072). Of all secondary outcomes, only the foot progression angle was associated with the dynamic arch index (p = 0.032) with greater external rotation in lower arched children. SIGNIFICANCE: Overall, we found only few associations between arch characteristics and running biomechanics in children. However, altered foot arch characteristics are of clinical interest. Future studies should focus on detailed foot biomechanics and include clinically diagnosed high and low arched children.

Postural stability in young healthy subjects - Impact of reduced base of support, visual deprivation, dual tasking.

OBJECTIVE: To provide normative postural stability data in young subjects. METHODS: Ninety-six healthy participants (58W, 28±6y) stood on a force plate during 60s. We measured effects of support width (feet apart, FA; feet together, FT), vision (eyes open, EO; closed, EC), and cognitive load (single task, ST; dual tasking, DT) on anteroposterior (AP) and medio-lateral (ML) ranges, area and planar velocity of center of pressure (COP) trajectory. RESULTS: All variables increased with FT (AP range, +15%; ML, +185%; area, +242%; velocity, +50%, p<0.0002 for all, MANOVA). Visual deprivation increased COP ranges with added constraints (FT or DT, p=0.002) and increased velocity in all conditions (FA/ST, +16%; DT, +18%; FT/ST, +29%; DT, +23%, p<0.0002 for all). Dual tasking reduced COP displacements with FT (AP range, EO, -15%; EC, -11%; ML range, EO, -19%; EC, -13%; area, EO, -40%; EC, -28%, p<0.0002 for all) and increased velocity in most conditions (FA/EO, +15%; FA/EC, +16%; FT/EO, +7%, p<0.0002 for all). CONCLUSION: In young healthy adults, base of support reduction increases COP displacements. Vision particularly affects postural stability with feet together or dual tasking. Dual tasking increases velocity but decreases COP displacements in challenging postural tasks, potentially by enhanced lower limb stiffness.

Wireless, accelerometry-triggered functional electrical stimulation of the peroneal nerve in spastic paresis: A randomized, controlled pilot study.

In hemiparesis, Wireless, Accelerometry-Triggered Functional Electrical Stimulation (WAFES) of the common peroneal nerve may hold intrinsic rehabilitative properties. The present pilot study analyzes WAFES against conventional therapy. Twenty adults with chronic hemiparesis (time since lesion 7(6) years; median (interquartile range)) were randomized into 2 10-week rehabilitation programs: a 45-minute (min) daily walk using WAFES (n = 10) and conventional physical therapy (CPT), 3 × 45 min per week (n = 10). The outcomes were 3D sagittal speed measurements, step length, cadence, maximal amplitude and velocity of hip, knee, and ankle during gait at free and fast speed without WAFES and clinical assessments of plantar flexor angles of shortening, spasticity, and weakness, before (D1) and after the program (W10). Kinematic and spasticity improvements occurred in the WAFES group only: (i) ankle dorsiflexion velocity (D1 versus W10, free speed, WAFES, +4(5)°/sec, p = 0.002; CPT, -3(8)°/sec, p = 0.007; fast, WAFES, +8(6)°/sec, p = 0.03; CPT, -1(4)°/sec, NS); (ii) maximal passive ankle dorsiflexion (WAFES,+26(85)%; CPT,+0(27)%; group-visit, p = 0.007) and knee flexion (WAFES, +13(17)%; CPT, -1(11)%; group-visit, p = 0.006) at fast speed only; (iii) 15% plantar flexor spasticity grade reduction with WAFES. Over 10 weeks, gait training using WAFES improved ankle and knee kinematics and reduced plantar flexor spasticity compared with CPT. Studies with longer WAFES use should explore functional effects.

Human static postures analysis using empirical mode decomposition.

The goal of this paper is to analyze the human stability during static postures using stabilometric signals. The effects of subject's visual input, feet position, age and gender are analyzed. Twenty eight healthy subjects have participated in this study. The center of pressure displacements were measured along the Medio-Lateral (ML) and Antero-Posterior (AP) directions. Empirical mode decomposition method is used to decompose the stabilometric signal into several elementary signals called Intrinsic Mode Functions (IMF). A stabilogram-diffusion method is used to generate the related diffusion curve of each IMF and a resulting index called Critical Point (CP) is calculated. The CP parameter showed significant differences between groups using repeated measure ANOVA, particularly in the ML direction in terms of visual modality, feet position, age and gender. The present findings may guide the rehabilitation process. Our proposed method compares favorably to conventional stabilometric analysis based on the center of pressure excursion calculation.

Effect of haptic supplementation on postural control of younger and older adults in an unstable sitting task.

Standing postural control is known to be altered during aging, but age-related changes in sitting postural control have scarcely been explored. The present experiment studied the roles of visual and haptic information in a sitting task in both young and older adults. Fifteen young and fifteen older adults participated in this study. Six experimental conditions were performed with eyes open and eyes closed: quiet sitting, rocker-board sitting, and 4 conditions of haptic supplementation, provided by a hand-held pen, during rocker-board sitting. Classical variables were extracted from the center of pressure (COP) and pen trajectories, and the stabilogram diffusion analysis was performed on the COP data. Three-way ANOVAs (Group×Vision×Condition) were carried out. Postural instability was strongly attenuated by haptic supplementation in both age groups. Furthermore, instability due to visual deprivation was compensated by haptic supplementation. Long- and short-term diffusion coefficients were smaller in conditions of haptic supplementation. The present study confirmed the effect of haptic supplementation on both open-loop and closed-loop mechanisms of postural control and extended it to unstable sitting in young and older adults despite the complex biomechanical systems involved in sitting postural tasks.

Effect of haptic supplementation on postural stabilization: A comparison of fixed and mobile support conditions.

It is well known in the literature of haptic supplementation that a "light touch" (LT) with the index finger on a stable surface increases postural stability. In view of potential application in the domain of mobility aids, it should however be demonstrated that haptic supplementation is effective even when provided by an unstable stick support. The present study aimed to explore the stabilizing effect of a three-digit "light grip" (LG) of different supports (fixed or mobile stick) in young people. Eleven participants (M=25.9 years) were tested in an upright standing task in six experimental conditions in which the mobility of the given support and its resistance in opposite direction to the body movement were manipulated. The RMS variability and the range of postural oscillations were measured. The results confirmed that the stabilizing effect of haptic supplementation is independent from the nature of the support (fixed or mobile) when sufficiently large sway-related contact forces on the fingers are provided. Future applications of this "mobile stick paradigm" to complex situations while targeting different groups of participants may help to approach everyday life situations in which an informational stick could potentially be of assistance to gain stability and mobility.