Search

An experimental study is performed to determine the head mechanics of American football helmets equipped with novel fiber energy absorbing material (FEAM). FEAM-based padding materials have substrates of textile fabrics and foam made with nylon fibers using electro-static flocking process. Both linear and angular accelerations of the sport helmets are determined under impact loads using a custom-built linear impactor and instrumented head. The effectiveness of padding materials and vinyl nitrile (VN) foam for impact loads on six different head positions that simulate two helmeted sport athletes in real-time helmet-to-helmet strike/impact is investigated. A high-speed camera is used to record and track neck flexion angles and compare them with pad effectiveness to better understand the head kinematics of struck players at three different impact speeds (6 m/s, 8 m/s, and 10 m/s). At impact speed of 6 m/s and 8 m/s, the FEAM-based padding material of 60 denier fibers showed superior resistance for angular acceleration. Although novel pads of VN foam flocked with 60 denier fibers outperformed with lowest linear acceleration for most of the head positions at low impact speed of 6 m/s, VN foam with no fibers demonstrated excellent performance for linear acceleration at other two speeds. [ABSTRACT FROM AUTHOR]

An experimental study is performed to determine the head mechanics of American football helmets equipped with novel fiber energy absorbing material (FEAM). FEAM-based padding materials have substrates of textile fabrics and foam made with nylon fibers using electro-static flocking process. Both linear and angular accelerations of the sport helmets are determined under impact loads using a custom-built linear impactor and instrumented head. The effectiveness of padding materials and vinyl nitrile (VN) foam for impact loads on six different head positions that simulate two helmeted sport athletes in real-time helmet-to-helmet strike/impact is investigated. A high-speed camera is used to record and track neck flexion angles and compare them with pad effectiveness to better understand the head kinematics of struck players at three different impact speeds (6 m/s, 8 m/s, and 10 m/s). At impact speed of 6 m/s and 8 m/s, the FEAM-based padding material of 60 denier fibers showed superior resistance for angular acceleration. Although novel pads of VN foam flocked with 60 denier fibers outperformed with lowest linear acceleration for most of the head positions at low impact speed of 6 m/s, VN foam with no fibers demonstrated excellent performance for linear acceleration at other two speeds.

Background: The use of smart phones has become increasingly popular and almost indispensable in contemporary life, but many studies have addressed that excessive use negatively affects the various developmental domains. Purpose: The purpose of this study was to examine the effect of prolonged smartphone use on the forward neck translation, neck flexion angle and handgrip power for duration of 8 weeks. Materials and Methods: Ninety students from nine different international schools in Sharjah, UAE, with age ranging between 13-17 years. Participated in this study. Subjects were divided into two groups based on their daily frequency of smartphone use. Group (I) using smart phones less than 4 hours/day and Group (II) using more than 4 hours/day. The Neck flexion angle and forward neck translation were measured by the posture assessment mobile application (PostureCo, Inc), during their normal straight upright postural standing position. Handgrip power was measured with a Handheld Dynamometer (HHD) for both dominant and non-dominant hands, with arms abducted 30 degrees and wrist slightly extended (10 degrees). Measures were repeated 3 times and the average was considered for data analysis. Results: After 8 weeks of smart phone usage, statistical analyses revealed significant increase and decrease in the forward neck translation and neck flexion angles respectively. On the other hand, there were no statistically significant differences in handgrip power in both groups. Conclusion: Our results revealed the significant effect of the prolonged use of smartphones on the neck flexion angle, forward head translation without affecting handgrip power. [ABSTRACT FROM AUTHOR]

This study examined the differences in neck muscle activity at various neck flexion angles in smartphone users with and without neck pain. Forty-four participants performed texting tasks for 1 min and 30 s. Neck muscle activity and pain in the neck were measured at different neck flexion angles. There was a difference in neck muscle activity for each of the neck flexion angles; the Cervical Erector Spinae (CES) muscle activity increased while the Upper Trapezius (UT) muscle activity decreased when at increased neck flexion angles. At neck flexion angle of 0°–15°, the activity of both CES and UT muscles were acceptably low. Smartphone users with neck pain had slightly higher muscle activity levels than smartphone users without neck pain. In conclusion, smartphone users should consider adopting neck flexion angles between 0 and 15 degrees during smartphone use as there is an association between this neck flexion angle range and reduced CES muscle activity. Practitioner summary: This study demonstrated that both smartphone users with and without neck pain should try to keep their neck flexion angle between 0° and 15° when using their smartphone. This would reduce neck muscle activity and the risk of developing neck disorders associated with smartphone use. [ABSTRACT FROM AUTHOR]