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.

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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.

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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.

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.

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