An evaluation of football helmets under impact conditions.

The impact attenuating characteristics of a sample of 81 football helmets used in competitive high school programs were determined using a Hodgson-Wayne State University (WSU) headform and a modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test protocol. The helmets, classified by liner type as suspension (37), padded-suspension (22), and padded (22) had been in use for 6 to 8 years. Each was subjected to two consecutive right rear boss impacts from a drop height of 1.5 m, onto a rigid anvil covered with a 45 durometer hardness rubber pad. Analogue signals from a triaxial accelerometer located at the center of gravity of the headform were analogue to digital (A/D) converted at 6060.6 Hz and processed on a Hewlett Packard 9845B minicomputer to yield a resultant acceleration-time curve from which peak acceleration (gpeak) and the Gadd Severity Index (GSI) were determined. The mean gpeak was 205 g for helmets with suspension liners, 165 g for helmets with padded-suspension liners, and 156 g for helmets with padded liners. Twenty-four suspension helmets and five padded or padded-suspension helmets had GSI values greater than 1200. Using a criterion of GSI1500, the failure rate for suspension helmets was 19% compared to 2% for padded and padded-suspension helmets combined. If the criterion chosen was GSI1200, the failure rate for suspension helmets was 65% as opposed to 11% for the padded and padded-suspension helmets combined. Suspension helmets are decidedly inferior under impact conditions to the padded and padded-suspension helmets.

Medial epicondylitis. An electromyographic analysis and an investigation of intervention strategies.

Flexor and extensor muscle-tendon unit activity at the elbow during the golf swing was recorded from subjects with and without medial epicondylitis. There was no significant difference in total swing time between symptomatic (1.23 +/- 0.15 sec) and asymptomatic (1.15 +/- 0.13 sec) subjects nor between golfers with low (1 to 6 handicap, N = 8) and high (11 to 19 handicap, N = 8) scoring abilities. Symptomatic and asymptomatic subjects displayed similar electromyographic profiles for flexor and extensor muscles of the forearm. Electromyographic activity of the common extensor muscles was persistent throughout the four swing phases, ranging from 33.59% of maximum voluntary contraction at address to 58.77% at contact. Common flexor muscles produced a consistent burst of electromyographic activity during contact phase (flexor burst, 90.77% of maximum voluntary contraction). Symptomatic subjects' mean flexor muscle electromyographic activity was significantly greater than that of asymptomatic subjects in both address and swing phases. When forearm brace and oversized grips were imposed on symptomatic subjects, there was no significant difference in mean electromyographic magnitude or muscle activation pattern during the golf swing. Thus, the method of symptomatic relief of the intervention strategies tested is still in question.

The effects of static stretching exercises and stationary cycling on range of motion at the hip joint*.

The objective of this study was to compare the effects of static stretching exercises and stationary cycling on hip range of motion measures immediately following exercise and after a 15-min period of rest or continued activity. The results showed that both exercises performed for equal time periods resulted in hip range of motion increases with no significant difference (p < 0.05) between the immediate effects of the two exercises. Fifteen minutes of cycling or inactivity did not result in significant differences (p < 0.05) from the initial gains resulting from the stretching, but did result in significant increases in hip flexion for the group that continued cycling. Based on the results of this study, static stretching and cycling were equally effective for increasing range of motion and retaining the increase for a 15-min period in a controlled environment, independent of activity.J Orthop Sports Phys Ther 1984;6(2):104-109.

Structural anthropometric measurements for wheelchair mobile adults.

Structural anthropometric measurements for males and females were determined for the wheelchair mobile adults. A photogrammetry methodology was used to obtain the measurements. The various subject demographics including age, level or type of dysfunction as well as the specified anthropometric dimensions of the wheelchair mobile subjects were identified. The data would be useful for the design of industrial workstations for wheelchair mobile adults. Present workstation design principles based on seated able-bodied anthropometric measurements would not be suitable for this population.

The Use of Electricity in Ligament and Tendon Repair.

In brief: The authors compared the effects of immobilization, early motion, and electrical stimulation on injured tendons in dogs and found that the healed tendons that had had electrical implants were much stronger. Therefore, they have dramatically altered their rehabilitation program for ligament and tendon repair. They implant electrical stimulators during surgery, and the patients are mobilized after one day. The authors say that while patients treated by traditional techniques are experiencing muscle atrophy, joint stiffness, and discomfort, their patients are enjoying greater mobility and earlier return to activities.

An ergonomic evaluation of infant life jackets: Donning time & donning accuracy.

Canada is considering the development of a new standard for infant/child life jackets. Eight currently available (approved and non-approved) infant/child life jackets were procured for evaluation. Fifty-six participants were chosen as a sample of convenience from the general public for testing. The life jackets were divided into two groups of four, which were donned on a soft infant manikin procured from the Red Cross. In 224 attempts at donning, only 43 (19%) attempts resulted in the life jacket being donned correctly in less than 1 min. Only one life jacket came close to a good design and passed the life jacket standard for donning time and accuracy. Failure rates were observed across all the participants irrespective of age, gender, experience with children and experience with recreational marine equipment. Accuracy and speed of donning the life jacket were hampered as the number of donning sub-tasks increased. It was concluded that it is possible to design a life jacket that can be donned correctly in under 1 min. The life jacket must be of simple, intuitive design and fall naturally into the anatomical shape of the child. A minimum number of ties, zips and clips should be used in the design, and if such connectors are used they should be color coded or of different shapes and sizes to avoid confusion.