Leonard JA, Gritsenko V, Ouckama R, Stapley PJ. Postural adjustments for online corrections of arm movements in standing humans.

No abstract

Modern sport helmets certified to various international safety standards have virtually eliminated the incidence of cranial fracture and fatal brain injury in contact sports; however, the occurrence of diffuse brain injuries (mTBI) are still prevalent. Local contact mechanics between the colliding surface (helmet/head) need to be considered as global measures of acceleration and are insensitive to load distribution measures which are indicative of helmet performance. The purpose of this study was to demonstrate the ability to capture localized load distribution response between the helmet and headform and to examine factors that may influence these measures. Twenty-five flexible force sensors were arranged in a 5 3 5 array about three impact sites (front, side, rear) of a 575 mm EN960 headform. Test factors included helmet model (5), impact location (3) and temperature (21°C, 225°C) as well as repeated impacts (3). Testing procedure followed the CSA Z262.1-09 standard at the defined locations. Average error calculated during sensor calibration was 2.8 6 1% with an R 2 value of 0.987 6 0.009. As expected, peak global force correlated well to peak acceleration (R 2 = 0.98) but weakly corresponded to peak focal force (R 2 = 0.22). Furthermore, both load distribution magnitudes and patterns were found to vary substantially with mixed effects between helmet models, impact locations, and temperatures. Given these findings, this novel approach may be used to quantify local contact mechanics between the colliding surface/helmet/head.

No abstract

This longitudinal 10-year study investigated the effects of inventory aging on ice hockey helmets' impact attenuation characteristics. Three unused helmet models with different foam padding materials (vinyl nitrile, multi-density vinyl nitrile, and expanded polypropylene) were impact tested at six sites around a surrogate headform on years 2, 6, and 10 (Y2, Y6, and Y10) after the date of manufacture. In general, peak acceleration (g) Y10 measures were greater than those reported in Y2 and Y6, although well below standard impact criteria levels. Visual inspection of helmets post-impact showed no conspicuous damage to liner or shell, although in several instances the binding glue had disintegrated allowing liners to shift or fall away from the shell. In summary, contemporary ice hockey helmets retain most of their robust impact attenuation characteristics 10 years in storage after manufacture date; however, adhesive tearing of padding from the shell needs to be addressed. Regular inspection of the helmet integrity by players, coaches, and trainers is paramount. Further testing of used helmets in a similar prospective manner is carried out to ensure safe helmet function.