Kinematic Validation of Postural Sway Measured by Biodex Biosway (Force Plate) and SWAY Balance (Accelerometer) Technology.

BACKGROUND: The Biodex Biosway® Balance System and SWAY Balance® Mobile smartphone application (SBMA) are portable instruments that assess balance function with force plate and accelerometer technology, respectively. The validity of these indirect clinical measures of postural sway merits investigation. PURPOSE: The purpose of this study was to investigate the concurrent validity of standing postural sway measurements by using the portable Biosway and SBMA systems with kinematic measurements of the whole body Center of Mass (COM) derived from a gold-standard reference, a motion capture system. STUDY DESIGN: Cross-sectional; repeated measures. METHODS: Forty healthy young adults (21 female, 19 male) participated in this study. Participants performed 10 standing balance tasks that included combinations of standing on one or two legs, with eyes open or closed, on a firm surface or foam surface and voluntary rhythmic sway. Postural sway was measured simultaneously from SBMA, Biosway, and the motion capture system. The linear relationships between the measurements were analyzed. RESULTS: Significant correlations were found between Biosway and COM velocity for both progressively challenging single and double leg stances (τ b = 0.3 to 0.5, p < 0.01 to <0.0001). SBMA scores and COM velocity were significantly correlated only for single leg stances (τ b = -0.5 to -0.6, p < 0.0001). SBMA scores had near-maximal values with zero to near-zero variance in double leg stances, indicating a ceiling effect. CONCLUSION: The force plate-based Biodex Biosway is valid for assessing standing postural sway for a wide range of test conditions and challenges to standing balance, whereas an accelerometer-based SWAY Balance smartphone application is valid for assessing postural sway in progressively challenging single leg stance but is not sensitive enough to detect lower-magnitude postural sway changes in progressively challenging double leg stances.

Effects of simulated neural mobilization on fluid movement in cadaveric peripheral nerve sections: implications for the treatment of neuropathic pain and dysfunction.

BACKGROUND AND PURPOSE: Neural mobilization techniques are used clinically to treat neuropathic pain and dysfunction. While selected studies report efficacy of these techniques, the mechanisms of benefit are speculative. The purpose of this study was to evaluate the effects of in vitro simulated stretch/relax neural mobilization cycles on fluid dispersion within sections of unembalmed cadaveric peripheral nerve tissue. METHODS: Bilateral sciatic nerve sections were harvested from six cadavers. Matched pairs of nerve sections were secured in a tissue tester and injected with a plasma/Toluidine Blue dye solution. Once the initial dye spread stabilized, the experimental nerve sections underwent 25 stretch/relaxation cycles (e.g. simulated neural mobilization) produced by a mechanical tissue tester. Post-test dye spread measurements were compared to pre-test measurements as well as control findings (no simulated mobilization). Data were analyzed using paired t-tests. RESULTS: Individual dye spread measurements were reliable [ICC(3,1) = 0·99]. The post-test intraneural fluid movement (dye spread) in the experimental section increased significantly with simulated neural mobilization compared to pre-test measurements (3·2±2·1 mm; P = 0·015) and control measurements (3·3±2·7 mm; P = 0·013). CONCLUSION: Repetitive simulated neural mobilization, incorporating stretch/relax cycles, of excised cadaveric peripheral nerve tissue produced an increase in intraneural fluid dispersion. Neural mobilization may alter nerve tissue environment, promoting improved function and nerve health, by dispersing tissue fluid and diminishing intraneural swelling and/or pressure.

The effects of neurodynamic mobilization on fluid dispersion within the tibial nerve at the ankle: an unembalmed cadaveric study.

OBJECTIVE: To evaluate the effects of neurodynamic mobilization on the fluid dynamics of the tibial nerve in cadavers. BACKGROUND: Evidence showing patients benefit from neural mobilization is limited. Mechanisms responsible for changes in patient symptoms are unclear. METHODS: Bilateral lower limbs of six unembalmed cadavers (n = 12) were randomized into matched pairs and dissected to expose the tibial nerve proximal to the ankle. Dye composed of Toulidine blue and plasma was injected into the nerve. The longitudinal dye spread was measured pre- and post-mobilization. The experimental group received the intervention consisting of 30 repetitions of passive ankle range of motion over the course of 1 minute. The matched control limb received no mobilization. Data were analysed using a 2×2 repeated measures ANOVA with subsequent t-tests for pairwise comparisons. RESULTS: Mean dye spread was 23.8±10.2 mm, a change of 5.4±4.7% in the experimental limb as compared to 20.7±6.0 mm, a change of -1.5±3.9% in the control limb. The ANOVA was significant (P⩽0.02) for interaction between group (experimental/control) and time (pre-mobilization/post-mobilization). t-test results were significant between pre- and post-mobilization of the experimental leg (P = 0.01), and between control and experimental limbs post-mobilization (P⩽0.02). CONCLUSION: Passive neural mobilization induces dispersion of intraneural fluid. This may be clinically significant in the presence of intraneural edema found in pathological nerves such as those found in compression syndromes.

Effect of sex hormones on neuromuscular control patterns during landing.

The purpose of the study was to investigate the effects of sex hormones across menstrual cycle phases on lower extremity neuromuscular control patterns during the landing phase of a drop jump. A repeated-measures design was utilized to examine sex hormone effects in 26 recreationally active eumenorrheic women. Varus/valgus knee angle and EMG activity from six lower extremity muscles were recorded during three drop jumps from a 50 cm platform in each phase of the menstrual cycle. Blood assays verified sex hormone levels and cycle phase. The semitendinosus muscle exhibited onset delays (p0.006) relative to ground contact during the luteal phase, and demonstrated a significant (p0.05) difference between early and late follicular phases. Muscle timing differences between the gluteus maximus and semitendinosus were decreased (p0.05) in the luteal compared to early follicular phases. These results suggest a different co-contractive behavior between the gluteus maximus and semitendinosus, signifying a shift in neuromuscular control patterns. It appears that female recreational athletes utilize a different neuromuscular control pattern for performing a drop jump sequence when estrogen levels are high (luteal phase) compared to when they are low (early follicular phase).