Head and neck anthropometry, vertebral geometry and neck strength in height-matched men and women
Journal of Biomechanics, Volume 41, Issue 1, Pages 114-121
A. Vasavada, J. Danaraj, G. Siegmund
Women have an increased incidence of whiplash injury and neck pain compared to men. Physical and numerical models represent one avenue to explore and potentially explain these gender differences, but a valid model of the female neck does not yet exist. A fundamental question in the development of a female neck model is whether female necks are simply scaled versions of male necks, or whether there are significant inter-gender geometrical differences. The goal of this study was to quantify differences in head and neck geometry and neck strength in pairs of male and female subjects matched for standing height and neck length. Based on 14 matched pairs of men and women, we found that most head and neck anthropometric parameters were significantly smaller in females compared to males. Moreover, gender differences in a number of neck anthropometry parameters (an average of 9-16% smaller in females) were larger than differences in head anthropometry parameters (an average of 3-6% smaller in females). Female vertebrae between C3 and C7 were significantly smaller than male vertebrae in the anterior-posterior dimension (p<0.012) but not in the medial-lateral dimension (p>0.07). Female necks were also significantly weaker than male necks (32% weaker in flexion and 20% weaker in extension; p<0.001), and these strength differences corresponded well to those predicted solely from the observed geometric differences. These results demonstrate that male and female necks are not geometrically similar and indicate that a female-specific model will be necessary to study gender differences in neck-related disorders.
Influence of anthropometry on the kinematics of the cervical spine and the risk of injury in sled tests in female volunteers
The objective of this study was to investigate the influence of anthropometric data on the kinematics of the cervical spine and the risk factors for sustaining a neck injury during rear-end collisions occurring in a sled test.
A rear-end collision with a velocity change (?V) of 6.3 km/h was simulated in a sled test with eight healthy female subjects. The study analysed the association of anthropometric data with the initial distance between the head and the head restraint, defined kinematic characteristics, the neck injury criterion (NIC) and the neck injury criterion minor (NICmin).
The head circumference is negatively associated (r = -0.598) with the initial distance between the head and the head restraint, the maximal head extension (r = -0.687) and the maximal dorsal angular head acceleration (r = -0.633). The body weight (r = 0.800), body height (r = 0.949) and thorax circumference (r = 0.632) are positively associated with the maximal ventral head translation. The neck length correlates positively with the NIC (r = 0.826) and negatively with the NICmin (r = -0.797).
Anthropometric factors influence the kinematics of the cervical spine and the risk of injury. A high risk of injury may be assumed for individuals with a small head circumference, long neck, tall body height and high body weight.
Keywords: Rear-end impact; Anthropometric; Head–neck kinematics; Volunteer sled tests; Whiplash
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Picking Apart Bamboo Couture
• By CHRISTINA BINKLEY
Fast-growing bamboo has an eco-friendly image.
Slinky, soft bamboo fabric has made its way into my wardrobe in the form of a number of buttery shirts and dresses. When I came across the eco-label Viridis Luxe, it wasn't Uma Thurman and Laura Dern's patronage of the brand that attracted me. It was the clothes' luxurious feel and comfortable styling.
Indeed, bamboo has had the most success among all the new "eco-textiles" on store shelves—fabric billed as environmentally friendly and made from materials such as soybeans, corn, milk, seaweed and recycled plastic. Bamboo shows up in clothes sold in Nordstrom and Saks Fifth Avenue, as well as sheets sold at Target, and it bears such deluxe labels as Ermenegildo Zegna, Rag & Bone and Ralph Lauren, as well as more eco-focused brands. Because it is so exotically soft, bamboo is often marketed alongside luxury fibers like silk and cashmere.
Bamboo's story sounds clear and appealing: like hemp, the plant grows quickly without the irrigation, pesticides or fertilizer often used to grow cotton. It's often sold as "biodegradable," and the plant's antimicrobial properties have been used to market athletic clothes made from the fiber. "People are switching from cotton to bamboo," says Aarti Doshi, regional manager for bamboo-fabric distributor Doshi Group, based in Mumbai, India.
When I looked below the surface, though, I found that bamboo fabric is less "eco" and "sustainable" than it seems. The bamboo used in textiles has to be heavily manipulated to go from stem to store. To create fabric, it's chopped up and dissolved in toxic solvents—the same process that recycles wood scraps into viscose or rayon. Indeed, bamboo fabric technically is rayon.
The Federal Trade Commission sued four small bamboo-clothing manufacturers in August, citing them for false labeling, among other concerns, under the 1958 Textile Fiber Products Identification Act. The companies had used language such as "natural," "biodegradable," and "antimicrobial." But bamboo fabric isn't natural, the FTC said, since it's a textile developed by chemists. The agency also said the biodegradable and antimicrobial qualities of the plant don't survive the manufacturing process.
In a bulletin titled "Have You Been Bamboozled by Bamboo Fabrics?" the FTC said that bamboo fabrics "are made using toxic chemicals in a process that releases pollutants into the air."
The FTC's four cases are close to being settled without penalties, but with the requirement that fabric be labeled as viscose or rayon, and without the claims about biodegradability and antimicrobial properties, says FTC staff attorney Korin Ewing.
The Jonäno brand also makes clothes with fabric derived from bamboo plants.
Of course, rayon doesn't have the same all-natural ring as bamboo. Salvatore Giardina, a designer and adjunct professor in textile development and marketing at the Fashion Institute of Technology in New York, says he works with hemp and linen but stopped using bamboo several years ago after a manufacturer told him it should be labeled as viscose. "I manufacture a very high-end product—there's no way I can put on my label 100% viscose," he says.
Bonnie Siefers, founder and designer of Jonäno, one of the apparel makers sued by the FTC, says she has stopped marketing her bamboo line as biodegradable or antimicrobial. She is also working with newer fabrics made from corn sugars—which technically make something like polyester, but without the petroleum base.
But a quick search on the Web shows hundreds of apparel makers still market bamboo fabrics as eco-friendly. Ms. Ewing notes they probably have good intentions. "We have to be sure that sellers do their homework," she says. Most bamboo is grown in China, where it's harder for U.S designers to monitor suppliers.
Of course, bamboo doesn't have to be processed heavily—witness the many home items, from furniture to flooring, on the market—to be used in products.
But some wearers have other gripes about bamboo. Mr. Giardina, the FIT professor, says he found that bamboo fabric is unstable and likely to stretch out of shape in damp weather. Uniform Knitters Ltd., a Hong Kong apparel manufacturer, abandoned bamboo fabrics because they tend to shrink and have odd variances in color, according to a company spokeswoman.
My bamboo clothes also proved somewhat unstable. After a few washes, tiny holes began to appear randomly in my new bamboo wardrobe. Hala Bahmet, the designer of Viridis Luxe, says the holes were the fault of too-thin yarn.
"Brands—us included—cranked out these delectable, lightweight, creamy garments that don't have the durability," she says. She now adds organic cotton to her clothes to improve durability, and she labels them "viscose from bamboo." She has had better success mixing hemp and cashmere in her sweaters, which are gorgeous.
Ms. Bahmet says she hopes the FTC concerns lead to research on better bamboo production, because it doesn't involve diverting an important food source such as corn to fabric production. She is optimistic that the FTC action will encourage scientists to research truly eco-friendly production methods for bamboo.
"Bamboo is just in its infancy as a fiber," she says. "It's not even a teenager yet."
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