Page 481

 Page 481

BODY MOVEMENTS WHEN STANDING.

 emphasized when a person stands with feet apart and it is a common experience that standing is sometimes made easier by adopting a wider stance. A healthy person may notice this fact only in situations that are particularly threatening to equilibrium such as when standing on a moving bus. Patients with problems of balance, however, often adopt a 'wide base' strategy quite naturally even in situations that are apparently undemanding. One obvious advantage of this strategy is that the area of support is increased as the feet are placed further apart and any disturbance of the position of the centre of mass would present less of a threat to lateral equilibrium. This is probably not the complete explanation since this strategy is not universally adopted by all patients with postural problems.

 The purpose of the present paper is to describe how in normal subjects different segments of the body move relative to each other in the two principal planes during quiet stance and how such movements are affected by altering stance width and removing visual information. Both of these factors are manipulated routinely in the clinical setting to test a patient's static postural ability by asking the subject to stand with feet together and eyes closed (Romberg's test). Visual input influences neural control of body sway. Stance width is thought primarily to be a mechanical factor, although we shall show with the aid of a mathematical model that it also exerts an important influence on the pattern of sway-induced afferent input. The way in which these two factors interact to influence the residual body movements during quiet stance provide some clues about the postural mechanisms used to achieve the task of bipedal stance. Part of these data have been published in brief form (Day, Steiger, Thompson & Marsden, 1990).

 METHODS 

With ethical committee approval thirty five normal male subjects were studied whose ages ranged from 29 to 63 years (45-9t 10-7 years mean ts.D.). Female subjects were not included in this study because of sex differences in the geometry of the skeletal frame and reported differences in the levels of baseline body sway (Overstall, Exton-Smith, Imms & Johnson, 1977). 

Subjects stood barefoot on a foroe platform (Kistler 9281B) facing and 1 m away from the corner of a room. The walls were draped with black curtains and a 1 cm red square was placed in the corer at eye height. When necessary, the wearing of spectacles was permitted to ensure that all subjects had normal binocular vision and were able to comfortably fixate this square. A non-contact, infrared motion detection system (Selspot II) was used to measure motion of various sites of the body in three dimensions. To achieve this, eight infrared-emitting diodes (IRED) were fixed with double-sided adhesive tape symmetrically on the left and right side of the back of the subject (Fig. 1) at the following levels: at the shoulders midway between acromion and mid-line; at the hips midway between anterior superior iliae spine and mid-line; at the knees in the popliteal fossa and at the ankles on the Achilles' tendon at the level of the malleoli. 

Stance width, or intermalleolar distance (IMD), was defined as the distance between the medial malleoli. Five IMDS (0, 4, 8, 16 and 32 cm) were studied in random order both with eyes open fixating the red square and with eyes closed. For each trial, subjects were asked to stand as still as possible with their hands together held relaxed in front of them while body motion and reaction force data were collected for 32 s. Data from the foroe plate and IREDS were digitized and collected with a sampling frequency of 100 Hz. Signal noise was reduced by averaging every four consecutive data pointa which lowered the effective sampling frequency to 25 Hz. This was considered an adequate sampling frequency since previous measurements of centre of pressure excursions that accompany body sway have shown that for young healthy subjecets the principal power is contained in frequencies below 1 Hz whereas in some elderly subjects there may be additional low power components between 1 and 3 Hz (Lucy & Hayes, 1985). Even for posturally unstable

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 站立时的身体运动。

  强调当一个人双脚分开站立时，通常的经验是，通过采取更宽的站姿，站立有时会更容易。 一个健康的人可能只有在对平衡特别有威胁的情况下才会注意到这一事实，例如站在行驶中的公共汽车上。 然而，有平衡问题的患者通常会很自然地采用“宽基”策略，即使是在显然要求不高的情况下。 这种策略的一个明显优点是，随着双脚分开放置得更远，支撑面积会增加，并且重心位置的任何干扰对横向平衡的威胁都较小。 这可能不是完整的解释，因为并非所有有姿势问题的患者都普遍采用这种策略。

  本文的目的是描述正常受试者在静止站立时身体的不同部分如何在两个主要平面上相对于彼此移动，以及这种运动如何受到改变站立宽度和去除视觉信息的影响。 这两个因素在临床环境中都被常规操作，以通过要求受试者双脚并拢站立并闭上眼睛来测试患者的静态姿势能力（Romberg 的测试）。 视觉输入影响身体摇摆的神经控制。 站立宽度主要被认为是一个机械因素，尽管我们将借助数学模型表明它也对摇摆诱导的传入输入模式产生重要影响。 这两个因素相互作用以影响安静站立期间剩余的身体运动的方式为用于实现双足站立任务的姿势机制提供了一些线索。 这些数据的一部分已经以简短的形式发表（Day、Steiger、Thompson & Marsden，1990）。

  方法

 经伦理委员会批准，研究了年龄为 29 至 63 岁（45-9t 10-7 岁平均 ts.D.）的 35 名正常男性受试者。 由于骨骼框架几何形状的性别差异和报告的基线身体摇摆水平的差异（Overstall，Exton-Smith，Imms＆Johnson，1977），女性受试者未包括在本研究中。

 受试者赤脚站在前平台（Kistler 9281B）上，面对房间的角落，距离房间角落 1 m。 墙壁上挂着黑色窗帘，一个 1 厘米的红色方块被放置在与眼睛同高的取芯器中。 必要时，允许佩戴眼镜以确保所有受试者具有正常的双眼视力并能够舒适地注视这个正方形。 非接触式红外运动检测系统 (Selspot II) 用于测量身体各个部位的三个维度的运动。 为了实现这一点，八个红外发光二极管 (IRED) 用双面胶带对称地固定在受试者背部左右两侧（图 1）的以下水平：在肩峰和肩峰之间的肩膀中间。 中线； 在髂前上棘与中线之间的臀部； 在腘窝的膝盖处和踝关节水平的跟腱上的脚踝处。

 站立宽度或内踝距离 (IMD) 被定义为内踝之间的距离。 五个 IMDS（0、4、8、16 和 32 厘米）以随机顺序进行研究，睁眼注视红色方块和闭眼。 在每次试验中，受试者被要求尽可能保持静止，双手放在面前放松，同时收集身体运动和反作用力数据 32 秒。 来自前板和 IREDS 的数据被数字化并以 100 Hz 的采样频率收集。 通过对每四个连续数据点进行平均来降低信号噪声，这将有效采样频率降低到 25 Hz。 这被认为是一个足够的采样频率，因为之前对伴随身体摇摆的压力偏移中心的测量表明，对于年轻健康的受试者，主要功率包含在低于 1 Hz 的频率中，而在一些老年受试者中，可能有额外的低功率分量介于 1 Hz 之间。 和 3 Hz (Lucy & Hayes, 1985)。 即使对于姿势不稳

Dì 481 yè

zhànlì shí de shēntǐ yùndòng.

 Qiángdiào dāng yīgè rén shuāng jiǎo fēnkāi zhànlì shí, tōngcháng de jīngyàn shì, tōngguò cǎiqǔ gèng kuān de zhàn zī, zhànlì yǒushí huì gèng róngyì. Yīgè jiànkāng de rén kěnéng zhǐyǒu zài duì pínghéng tèbié yǒu wēixié de qíngkuàng xià cái huì zhùyì dào zhè yī shìshí, lìrú zhàn zài háng shǐ zhōng de gōnggòng qìchē shàng. Rán'ér, yǒu pínghéng wèntí de huànzhě tōngcháng huì hěn zìrán dì cǎiyòng “kuān jī” cèlüè, jíshǐ shì zài xiǎnrán yāoqiú bù gāo de qíngkuàng xià. Zhè zhǒng cèlüè de yīgè míngxiǎn yōudiǎn shì, suízhe shuāng jiǎo fēnkāi fàngzhì dé gèng yuǎn, zhīchēng miànjī huì zēngjiā, bìngqiě zhòngxīn wèizhì de rènhé gānrǎo duì héngxiàng pínghéng de wēixié dōu jiào xiǎo. Zhè kěnéng bùshì wánzhěng de jiěshì, yīnwèi bìngfēi suǒyǒu yǒu zīshì wèntí de huànzhě dū pǔbiàn cǎiyòng zhè zhǒng cèlüè.

 Běnwén de mùdì shì miáoshù zhèngcháng shòu shì zhě zài jìngzhǐ zhànlì shí shēntǐ de bùtóng bùfèn rúhé zài liǎng gè zhǔyào píngmiàn shàng xiàng duìyú bǐcǐ yídòng, yǐjí zhè zhǒng yùndòng rúhé shòudào gǎibiàn zhànlì kuāndù hé qùchú shìjué xìnxī de yǐngxiǎng. Zhè liǎng gè yīnsù zài línchuáng huánjìng zhōng dōu bèi chángguī cāozuò, yǐ tōngguò yāoqiú shòu shì zhě shuāng jiǎo bìnglǒng zhànlì bìng bì shàng yǎnjīng lái cèshì huànzhě de jìngtài zīshì nénglì (Romberg de cèshì). Shìjué shūrù yǐngxiǎng shēntǐ yáobǎi de shénjīng kòngzhì. Zhànlì kuāndù zhǔyào bèi rènwéi shì yīgè jīxiè yīnsù, jǐnguǎn wǒmen jiāng jièzhù shùxué móxíng biǎomíng tā yě duì yáobǎi yòudǎo de chuán rù shūrù móshì chǎnshēng zhòngyào yǐngxiǎng. Zhè liǎng gè yīnsù xiānghù zuòyòng yǐ yǐngxiǎng ānjìng zhànlì qíjiān shèngyú de shēntǐ yùndòng de fāngshì wèi yòng yú shíxiàn shuāng zú zhànlì rènwù de zīshì jīzhì tígōngle yīxiē xiànsuǒ. Zhèxiē shùjù de yībùfèn yǐjīng yǐ jiǎnduǎn de xíngshì fǎ biǎo (Day,Steiger,Thompson& Marsden,1990).

 Fāngfǎ

jīng lúnlǐ wěiyuánhuì pīzhǔn, yánjiūle niánlíng wèi 29 zhì 63 suì (45-9t 10-7 suì píngjūn ts.D.) De 35 míng zhèngcháng nánxìng shòu shì zhě. Yóuyú gǔgé kuàngjià jǐhé xíngzhuàng dì xìngbié chāyì hé bàogào de jīxiàn shēntǐ yáobǎi shuǐpíng de chāyì (Overstall,Exton-Smith,Imms&Johnson,1977), nǚxìng shòu shì zhě wèi bāokuò zài běn yánjiū zhōng.

Shòu shì zhě chìjiǎo zhàn zài qián píngtái (Kistler 9281B) shàng, miàn duì fángjiān de jiǎoluò, jùlí fángjiān jiǎoluò 1 m. Qiángbì shàng guàzhe hēisè chuānglián, yīgè 1 límǐ de hóngsè fāngkuài bèi fàngzhì zài yǔ yǎnjīng tóng gāo de qǔ xīn qì zhōng. Bìyào shí, yǔnxǔ pèidài yǎnjìng yǐ quèbǎo suǒyǒu shòu shì zhě jùyǒu zhèngcháng de shuāngyǎn shìlì bìng nénggòu shūshì de zhùshì zhège zhèngfāngxíng. Fēi jiēchù shì hóngwài yùndòng jiǎncè xìtǒng (Selspot II) yòng yú cèliáng shēntǐ gège bùwèi de sān gè wéidù de yùndòng. Wèile shíxiàn zhè yīdiǎn, bā gè hóngwài fāguāng èrjíguǎn (IRED) yòng shuāng miàn jiāodài duìchèn de gùdìng zài shòu shì zhě bèibù zuǒyòu liǎng cè (tú 1) de yǐxià shuǐpíng: Zài jiān fēng hé jiān fēngzhī jiān de jiānbǎng zhōngjiān. Zhōngxiàn; zài qià qián shàng jí yǔ zhōngxiàn zhī jiān de túnbù; zài guó wō de xīgài chù hé huái guānjié shuǐpíng de gēn jiàn shàng de jiǎohuái chù.

Zhànlì kuāndù huò nèihuái jùlí (IMD) bèi dìngyì wèi nèihuái zhī jiān de jùlí. Wǔ gè IMDS(0,4,8,16 hé 32 límǐ) yǐ suíjī shùnxù jìnxíng yánjiū, zhēng yǎn zhùshì hóngsè fāngkuài hé bì yǎn. Zài měi cì shìyàn zhōng, shòu shì zhě bèi yāoqiú jǐn kěnéng bǎochí jìngzhǐ, shuāngshǒu fàng zài miànqián fàngsōng, tóngshí shōují shēntǐ yùndòng hé fǎnzuòyòng lì shùjù 32 miǎo. Láizì qián bǎn hé IREDS de shùjù bèi shùzìhuà bìng yǐ 100 Hz de cǎiyàng pínlǜ shōují. Tōngguò duì měi sì gè liánxù shùjù diǎn jìnxíng píngjūn lái jiàngdī xìnhào zàoshēng, zhè jiāng yǒuxiào cǎiyàng pínlǜ jiàngdī dào 25 Hz. Zhè bèi rènwéi shì yīgè zúgòu de cǎiyàng pínlǜ, yīn wéi zhīqián duì bànsuí shēntǐ yáobǎi de yālì piān yí zhōngxīn de cèliáng biǎomíng, duìyú niánqīng jiànkāng de shòu shì zhě, zhǔyào gōnglǜ bāohán zài dī yú 1 Hz de pínlǜ zhōng, ér zài yīxiē lǎonián shòu shì zhě zhōng, kěnéng yǒu éwài de dī gōnglǜ fènliàng jiè yú 1 Hz zhī jiān. Hé 3 Hz (Lucy& Hayes, 1985). Jíshǐ duì yú zīshì bù wěn