郭路清 吳巧英
摘要: 為探究在運(yùn)動(dòng)中不同支撐強(qiáng)度文胸對(duì)乳房晃動(dòng)的影響,本文選擇3名75C罩杯女性和3件不同支撐強(qiáng)度文胸,利用QUALISYS動(dòng)態(tài)捕捉儀采集了受試者在3種運(yùn)動(dòng)速度下的乳房位移數(shù)據(jù)。通過(guò)建立軀干坐標(biāo)系,獲得乳房相對(duì)軀干的位移,并運(yùn)用SPSS進(jìn)行統(tǒng)計(jì)分析。結(jié)果表明:隨著運(yùn)動(dòng)速度的增加,乳房相對(duì)位移極差在X、Y、Z方向上均隨之增大,且當(dāng)速度從6 km/h增加到8 km/h時(shí),乳房在Z方向上的增幅約為X方向的2倍;相較于普通文胸,高支撐運(yùn)動(dòng)文胸可減少乳房X、Y方向上約30%~50%的晃動(dòng),Z方向約20%~40%,總體優(yōu)于中支撐運(yùn)動(dòng)文胸約5%~15%。對(duì)C罩杯女性而言,運(yùn)動(dòng)時(shí)穿著高支撐運(yùn)動(dòng)文胸可有效減小乳房三維晃動(dòng)幅度,尤其是前后和左右方向的晃動(dòng)。
關(guān)鍵詞: 運(yùn)動(dòng)速度;支撐強(qiáng)度;乳房晃動(dòng);三維動(dòng)態(tài)捕捉;軀干坐標(biāo)系;相對(duì)位移極差
中圖分類號(hào): TS941.17
文獻(xiàn)標(biāo)志碼: A
文章編號(hào): 1001-7003(2023)04-0080-08
引用頁(yè)碼:
041111
DOI: 10.3969/j.issn.1001-7003.2023.04.011(篇序)
隨著自律、健康、體態(tài)美等觀念的傳播,越來(lái)越多女性開始積極投身于健身運(yùn)動(dòng)。然而由于乳房沒(méi)有骨骼和肌肉的支撐,運(yùn)動(dòng)會(huì)導(dǎo)致乳房晃動(dòng),并拉扯皮膚和結(jié)締組織[1-2],使人產(chǎn)生生理上的不適和疼痛感,且這種影響與運(yùn)動(dòng)劇烈程度、罩杯大小及乳房晃動(dòng)幅度呈正相關(guān)[3-4]。據(jù)研究顯示,有超80%的大胸女性(>B罩杯)在運(yùn)動(dòng)中有乳房不適或疼痛經(jīng)歷,其中超過(guò)50%的調(diào)查對(duì)象認(rèn)為是運(yùn)動(dòng)和文胸穿著不當(dāng)導(dǎo)致的[5-6],而在運(yùn)動(dòng)中穿著合適的運(yùn)動(dòng)文胸可使其得到有效緩解[7]。因此,很有必要研究不同運(yùn)動(dòng)強(qiáng)度下的乳房運(yùn)動(dòng)規(guī)律,為具有較好乳房運(yùn)動(dòng)舒適性的文胸產(chǎn)品的設(shè)計(jì)研發(fā)提供理論依據(jù)。
研究顯示,依據(jù)運(yùn)動(dòng)的強(qiáng)度種類和罩杯大小可將運(yùn)動(dòng)文胸分為低、中、高支撐強(qiáng)度[8-9],一般低支撐強(qiáng)度文胸是針對(duì)胸部偏小的A罩杯女性或進(jìn)行瑜伽、步行等低強(qiáng)度運(yùn)動(dòng)而設(shè)計(jì)的;中支撐強(qiáng)度文胸適用于胸部較大的女性或競(jìng)走、慢跑、騎行等運(yùn)動(dòng);高支撐強(qiáng)度文胸適用于快速跑、拳擊、跳繩等運(yùn)動(dòng)
幅度較大的訓(xùn)練,對(duì)文胸的包裹性、面料及熱濕性有更高的要求。但針對(duì)不同支撐強(qiáng)度文胸是否會(huì)影響乳房運(yùn)動(dòng)穩(wěn)定性及其影響程度的研究比較有限,以至很多女性對(duì)運(yùn)動(dòng)文胸缺乏了解,在運(yùn)動(dòng)時(shí),仍穿著普通文胸或緊身衣來(lái)代替運(yùn)動(dòng)文胸[10]。綜上,本文以C罩杯年輕女性為實(shí)驗(yàn)對(duì)象,利用三維動(dòng)態(tài)捕捉系統(tǒng),研究在不同運(yùn)動(dòng)速度下,分別穿著普通文胸、中支撐運(yùn)動(dòng)文胸和高支撐運(yùn)動(dòng)文胸時(shí),乳房不同部位在X、Y、
Z方向上相對(duì)位移極差的差異,進(jìn)一步量化運(yùn)動(dòng)文胸對(duì)乳房所提供的生物力學(xué)支撐性能,以期為運(yùn)動(dòng)文胸的開發(fā)設(shè)計(jì)和消費(fèi)者的合理選購(gòu)提供指導(dǎo)。
1 實(shí)驗(yàn)與方法
1.1 對(duì)象和樣衣
1.1.1 對(duì) 象
本文實(shí)驗(yàn)對(duì)象為3名體型接近、乳房尺寸為75C的未婚健康女性,無(wú)妊娠或哺乳經(jīng)歷。被試者基本信息如表1所示。
1.1.2 樣 衣
基于對(duì)普通文胸和運(yùn)動(dòng)文胸的市場(chǎng)調(diào)研,本文選擇了李寧品牌推薦的2款運(yùn)動(dòng)文胸和1款Ubra普通(軟支撐)文胸,尺寸均為M碼,適合75C罩杯女性穿著,款式如圖1所示。文胸功能、成分、下圍尺寸等如表2所示。
普通(軟支撐)文胸為具有一定支撐能力但不會(huì)使乳房產(chǎn)生較大變形的無(wú)鋼圈背心式文胸P-0。中支撐運(yùn)動(dòng)文胸為具有下圍彈力帶,單層彈性面料的適用于競(jìng)走、騎行等運(yùn)動(dòng)的文胸Y-Ⅰ。高支撐運(yùn)動(dòng)文胸為適用于跑步、球類、拳擊等運(yùn)動(dòng)設(shè)計(jì)的雙層帶網(wǎng)眼面料的文胸Y-Ⅱ,2款運(yùn)動(dòng)文胸均為工字形結(jié)構(gòu)。
1.2 動(dòng)作捕捉實(shí)驗(yàn)
1.2.1 測(cè)試設(shè)備
QUALISYS三維動(dòng)態(tài)捕捉系統(tǒng)被用于獲取測(cè)試點(diǎn)位的三維運(yùn)動(dòng)軌跡。三維動(dòng)作捕捉系統(tǒng)基于光學(xué)原理,利用粘貼在物體表面的被動(dòng)Marker球,通過(guò)反光捕捉獲得該標(biāo)記點(diǎn)在運(yùn)動(dòng)中每一時(shí)刻(每0.01 s捕捉一次)的三維坐標(biāo),通過(guò)對(duì)坐標(biāo)點(diǎn)的處理,得到其三維運(yùn)動(dòng)軌跡。測(cè)試場(chǎng)地中間放置一臺(tái)優(yōu)步Y(jié)B-521DL跑步機(jī),周圍環(huán)繞9個(gè)Oqus500+高速視頻運(yùn)動(dòng)捕捉攝像機(jī)。其他輔助工具有卷尺、記號(hào)筆、醫(yī)用膠帶等。
1.2.2 標(biāo)記點(diǎn)的選取
前人研究表明人體左右乳房運(yùn)動(dòng)趨勢(shì)相似[11],故本文選擇左乳房進(jìn)行研究,選取乳頭點(diǎn)(B1)、乳頭點(diǎn)正上側(cè)5 cm(B2)、乳頭點(diǎn)正外側(cè)5 cm(B3)、乳頭點(diǎn)正下側(cè)5 cm(B4)及乳頭點(diǎn)正內(nèi)側(cè)5 cm(B5)共5點(diǎn)代表乳房運(yùn)動(dòng)。
乳房運(yùn)動(dòng)涉及乳房自身運(yùn)動(dòng)和人體軀干運(yùn)動(dòng)。盡管乳房自身運(yùn)動(dòng)是引起乳房不適的主要原因[12],但其位移數(shù)據(jù)無(wú)法由動(dòng)捕設(shè)備直接測(cè)得,因此,還需要在人體上選擇參考點(diǎn)來(lái)代表軀干運(yùn)動(dòng),以排除軀干6個(gè)自由度的運(yùn)動(dòng)[13],將乳房自身運(yùn)動(dòng)與軀干運(yùn)動(dòng)分離開來(lái)。由于乳房位置受軀干前傾彎曲、身體扭轉(zhuǎn)及呼吸作用的影響,在選擇可代表軀干運(yùn)動(dòng)的參考點(diǎn)時(shí),應(yīng)盡量選擇與骨骼運(yùn)動(dòng)、胸廓運(yùn)動(dòng)一致的軀干參考點(diǎn),以獲取較為精確的乳房位移數(shù)據(jù)。國(guó)家生物力學(xué)協(xié)會(huì)認(rèn)證人體胸部中線處的胸骨上切跡點(diǎn)及劍突點(diǎn)可以相對(duì)準(zhǔn)確地代表胸廓運(yùn)動(dòng)規(guī)律[14],而左肋弓下緣可較為準(zhǔn)確地代表骨骼運(yùn)動(dòng)[15],且這3點(diǎn)分別位于乳房的內(nèi)上側(cè)、內(nèi)側(cè)和下側(cè),為3個(gè)獨(dú)立非共線點(diǎn),構(gòu)成了乳房和軀干的分割平面。因此,本文選取了胸骨上切跡點(diǎn)(Oa)、劍突點(diǎn)(Ob)及左肋弓下緣(第十根肋骨下緣,與BP點(diǎn)對(duì)齊)(Oc)共3點(diǎn)作為軀干運(yùn)動(dòng)參考點(diǎn),建立冠狀面軀干坐標(biāo)系。乳房點(diǎn)及軀干點(diǎn)的標(biāo)記位置如圖2所示。8個(gè)標(biāo)記點(diǎn)應(yīng)同時(shí)測(cè)量,以減少實(shí)驗(yàn)誤差。
1.2.3 測(cè)試過(guò)程
首先對(duì)三維動(dòng)作捕捉系統(tǒng)進(jìn)行校正,并告知受試者在走路和跑步實(shí)驗(yàn)過(guò)程中應(yīng)注意的事項(xiàng),避免因姿勢(shì)不符常態(tài)或出現(xiàn)多余動(dòng)作而導(dǎo)致實(shí)驗(yàn)誤差。然后讓受試者先自主進(jìn)行5 min拉伸運(yùn)動(dòng),熱身運(yùn)動(dòng)過(guò)后依次換上實(shí)驗(yàn)文胸,并在8個(gè)標(biāo)記點(diǎn)處粘貼被動(dòng)Marker球。接著讓受試者在跑步機(jī)上分別以4 km/h(快走)、6 km/h(慢跑)、8 km/h(快速跑)的速度進(jìn)行走路或跑步運(yùn)動(dòng),待運(yùn)動(dòng)速度穩(wěn)定后,采集15 s數(shù)據(jù),截取其中采集率為100%的5 s數(shù)據(jù)作為實(shí)驗(yàn)數(shù)據(jù),每款文胸在每種速度下的實(shí)驗(yàn)均重復(fù)3次。
1.3 相對(duì)坐標(biāo)系的建立
由動(dòng)態(tài)捕捉系統(tǒng)直接獲得的三維坐標(biāo)數(shù)據(jù)為各標(biāo)記點(diǎn)在大地坐標(biāo)系下的三維運(yùn)動(dòng)軌跡,因此需要通過(guò)建立相對(duì)坐標(biāo)系,將大地坐標(biāo)系下的乳房運(yùn)動(dòng)數(shù)據(jù)轉(zhuǎn)化為相對(duì)軀干的位移數(shù)據(jù)。
1.3.1 確定相對(duì)坐標(biāo)系方向
以軀干標(biāo)記點(diǎn)Oa、Ob、Oc三個(gè)點(diǎn)確定相對(duì)位移坐標(biāo)系i,規(guī)定Ob為坐標(biāo)原點(diǎn),相對(duì)坐標(biāo)系方向如圖3所示。ObOa確定Z軸方向,代表垂直方向,記為z→,向上為正,向下為負(fù);三點(diǎn)確定平面法向量nx=ObOa×ObOc為X軸,代表前后方向,記為x→,向后為正,向前為負(fù);根據(jù)向量叉積的右手定則XOZ面的法向量ny=nx×ObOa為Y軸,代表左右方向,記為y→,向右為正,向左為負(fù)。
1.3.2 坐標(biāo)轉(zhuǎn)換
運(yùn)用空間向量理論建立相對(duì)位移坐標(biāo)系后,得到的新三維坐標(biāo)系由三個(gè)可計(jì)算得到的面構(gòu)成,分別為XOY面、XOZ面和YOZ面。利用點(diǎn)到面的距離公式,計(jì)算乳房各點(diǎn)分別到
三個(gè)平面的距離,即可得到乳房各點(diǎn)的相對(duì)坐標(biāo)。
設(shè)人體運(yùn)動(dòng)過(guò)程中的某一時(shí)刻,軀干3點(diǎn)坐標(biāo)為(Oa(Xa,Ya,Za)、Ob(Xb,Yb,Zb)、Oc(Xc,Yc,Zc),則有:
z→=ObOa=(Xa-Xb,Ya-Yb,Za-Zb)(1)
XY面的點(diǎn)法式方程為:
(Xa-Xb)(X-Xb)+(Ya-Yb)(Y-Yb)+(Za-Zb)(Z-Zb)=0(2)
以乳頭點(diǎn)B1(X1,Y1,Z1)為例,在新的軀干坐標(biāo)系i中,B1點(diǎn)在Z軸的相對(duì)坐標(biāo)為:
Zi=(Xa-Xb)(X1-Xb)+(Ya-Yb)(Y1-Yb)+(Za-Zb)(Z1-Zb)(Xa-Xb)(Xa-Xb)+(Ya-Yb)(Ya-Yb)+(Za-Zb)(Za-Zb)(3)
Xi、Yi計(jì)算原理同上,乳房其余點(diǎn)的相對(duì)坐標(biāo)計(jì)算也同上。由于人體是持續(xù)運(yùn)動(dòng)的,所以運(yùn)動(dòng)周期中每個(gè)時(shí)刻都要進(jìn)行計(jì)算,最終可得到乳房各點(diǎn)相對(duì)位移數(shù)據(jù)。
2 結(jié)果與分析
2.1 數(shù)據(jù)處理
首先對(duì)乳房和軀干各標(biāo)記點(diǎn)的所有原始數(shù)據(jù)進(jìn)行預(yù)處理,通過(guò)去除明顯錯(cuò)誤和異常的數(shù)據(jù),平滑其三維運(yùn)動(dòng)軌跡。然后根據(jù)3個(gè)軀干點(diǎn)的三維坐標(biāo)數(shù)據(jù)建立新的軀干坐標(biāo)系(相對(duì)坐標(biāo)系),接著將乳房5點(diǎn)的所有三維坐標(biāo)數(shù)據(jù)分別帶入1.3.2的公式中進(jìn)行計(jì)算,便可得到乳房各點(diǎn)相對(duì)于軀干的位移數(shù)據(jù),即相對(duì)位移。
乳房相對(duì)位移極差為1個(gè)穩(wěn)定周期(5 s)內(nèi)相對(duì)位移的最大值與最小值之差,3次重復(fù)實(shí)驗(yàn)所得數(shù)據(jù)的均值作為乳房相對(duì)位移極差測(cè)試結(jié)果。以Z方向?yàn)槔?,在新的軀干坐標(biāo)系下,相對(duì)位移最大值代表了乳房各點(diǎn)向上運(yùn)動(dòng)的最大位移,最小值代表了其向下運(yùn)動(dòng)的最大位移。因此,相對(duì)位移極差值的大小可以反映乳房的晃動(dòng)幅度。極差值越大,說(shuō)明乳房位移幅度越大,乳房晃動(dòng)越劇烈,表明文胸對(duì)乳房的減震效果越差[16]。計(jì)算3位受試者的3款文胸×3種運(yùn)動(dòng)速度×3個(gè)方向×5個(gè)標(biāo)記點(diǎn)下的乳房相對(duì)位移極差平均值,如表3所示。
2.2 數(shù)據(jù)分析
2.2.1 多因素方差分析
選擇運(yùn)動(dòng)速度n(3個(gè)水平)、文胸支撐強(qiáng)度m(3個(gè)水平)、乳房測(cè)量點(diǎn)位置l(5個(gè)水平)作為自變量,X、Y、Z方向的乳房相對(duì)位移極差為因變量,使用SPSS 22.0對(duì)數(shù)據(jù)進(jìn)行多因素方差分析,顯著水平為0.05。結(jié)果顯示:X、Y方向因素n,m和l檢驗(yàn)結(jié)果均為P<0.01;Z方向因素n和m為P<0.01,因素l為P<0.05;說(shuō)明運(yùn)動(dòng)速度、文胸支撐強(qiáng)度及乳房測(cè)量位置對(duì)乳房在X、Y、Z三個(gè)方向上的相對(duì)位移極差均存在顯著影響;且X方向運(yùn)動(dòng)速度×測(cè)量點(diǎn)存在交互作用(P<0.05);Y方向運(yùn)動(dòng)速度×測(cè)量點(diǎn),文胸支撐強(qiáng)度×測(cè)量點(diǎn)分別存在交互作用(P<0.05)。說(shuō)明X方向上,乳房5個(gè)測(cè)量部位相對(duì)位移極差值的大小受運(yùn)動(dòng)速度的影響,Y方向則分別受到運(yùn)動(dòng)速度和文胸支撐強(qiáng)度的影響。綜上可知,乳房5個(gè)測(cè)量點(diǎn)間的相對(duì)位移極差存在顯著差異,即
在研究乳房運(yùn)動(dòng)時(shí),不可僅取乳頭點(diǎn)來(lái)代表整個(gè)乳房的運(yùn)動(dòng)規(guī)律。
2.2.2 不同運(yùn)動(dòng)速度對(duì)乳房X、Y、Z方向位移的影響
1) X方向。3種運(yùn)動(dòng)速度下乳房相對(duì)位移極差及兩相鄰速度間的差值如圖4所示。由圖4可知,運(yùn)動(dòng)速度的增加會(huì)導(dǎo)致乳房前后晃動(dòng)愈加劇烈。在4 km/h和6 km/h的運(yùn)動(dòng)速度下,乳房5點(diǎn)相對(duì)位移極差均無(wú)明顯差異,且當(dāng)運(yùn)動(dòng)速度從4 km/h增加到6 km/h時(shí),乳房5點(diǎn)相對(duì)位移極差變化具有一致性,均有不到5 mm的增幅;而從6 km/h變化為8 km/h時(shí),乳房5點(diǎn)位移極差值的增幅存在顯著差異(P<0.05),即B1、B3、B5點(diǎn)位移(約10 mm)顯著大于B2、B4點(diǎn)處位移(約5 mm)。通過(guò)直觀比較三種文胸,發(fā)現(xiàn)運(yùn)動(dòng)文胸可有效控制乳房晃動(dòng),且高支撐運(yùn)動(dòng)文胸表現(xiàn)較優(yōu),但B1、B3、B5點(diǎn)處位移始終保持偏大。由此可見,乳房乳頭點(diǎn)及其水平線上位置的前后晃動(dòng)在高速運(yùn)動(dòng)下會(huì)更加劇烈。
2) Y方向。3種文胸在不同運(yùn)動(dòng)速度(4、6、8 km/h)下乳房5點(diǎn)相對(duì)位移極差及兩相鄰速度間的差值如圖5所示。由圖5(a)可知,隨著運(yùn)動(dòng)速度的增加,乳房5點(diǎn)相對(duì)位移極差值隨之增加。相較于4 km/h,在6 km/h時(shí)乳房5點(diǎn)相對(duì)位移極差值均有不到5mm的增幅,5點(diǎn)間差異不明顯(P>0.05);而當(dāng)運(yùn)動(dòng)速度從6 km/h增加到8 km/h時(shí),乳房5點(diǎn)相對(duì)位移極差明顯增大,且B1、B4、B5點(diǎn)處相對(duì)位移極差明顯大于B2、B3(P<0.05),分析認(rèn)為這是由于軟支撐文胸對(duì)乳房的包裹作用較弱,使得乳房上過(guò)乳頭點(diǎn)的豎直線及其內(nèi)側(cè)部位在跑步過(guò)程中左右晃動(dòng)較明顯。
比較圖5可知,相對(duì)于普通文胸(P-0),穿著運(yùn)動(dòng)文胸(Y-Ⅰ和Y-Ⅱ)不僅能夠有效減小乳房左右晃動(dòng),還使得乳房5點(diǎn)的左右晃動(dòng)差異有所減小,表明運(yùn)動(dòng)文胸可在一定程度上增加乳房5點(diǎn)運(yùn)動(dòng)的一致性和穩(wěn)定性。
3) Z方向。圖6展示了穿著3種支撐強(qiáng)度文胸在4、6、8 km/h的運(yùn)動(dòng)速度下,乳房5點(diǎn)相對(duì)位移極差值隨速度變化呈現(xiàn)的共同規(guī)律:運(yùn)動(dòng)速度從4 km/h增加到6 km/h時(shí),乳房5點(diǎn)位移變化基本一致,也均明顯小于5 mm;而當(dāng)運(yùn)動(dòng)速度增加到8 km/h時(shí),乳房上下晃動(dòng)明顯加劇,而乳房5點(diǎn)相對(duì)位移極差的增幅差異較小,穿著P-0時(shí)增幅約為14 mm,Y-Ⅰ時(shí)約為13 mm,Y-Ⅱ時(shí)約為12 mm。
綜上,運(yùn)動(dòng)速度越大,乳房晃動(dòng)越劇烈,而文胸支撐強(qiáng)度的提高對(duì)乳房有明顯控制保護(hù)作用。當(dāng)運(yùn)動(dòng)速度從4 km/h增加到6 km/h時(shí),乳房在三個(gè)方向的位移幅度變化普遍低于5 mm;而從6 km/h增加到8 km/h時(shí),乳房5點(diǎn)在X、Y、Z方向的增幅約在5~15 mm,不同方向位移增幅大小依次為Z>Y>X,其中Z方向增幅約為X方向的2倍,但X、Y方向不同測(cè)量點(diǎn)之間相對(duì)位移極差值的差異性更加明顯。
2.2.3 不同支撐強(qiáng)度運(yùn)動(dòng)文胸對(duì)乳房減震效果比較
為進(jìn)一步量化穿著不同支撐強(qiáng)度運(yùn)動(dòng)文胸在不同速度下的乳房運(yùn)動(dòng)差異,求取3名受試者在4、6 km/h和8 km/h的運(yùn)動(dòng)速度下,相較于穿著P-0,分別比較穿著Y-Ⅰ或Y-Ⅱ時(shí),乳房各點(diǎn)在X、Y、Z方向上的相對(duì)位移極差減少百分比的平均值,結(jié)果如圖7所示。相對(duì)位移極差減少百分比(S)為:
S/%=d0-dd0×100(4)
式中:d0為穿著P-0時(shí)乳房各點(diǎn)的位移極差值,d為穿著Y-Ⅰ or Y-Ⅱ時(shí)乳房各點(diǎn)位移極差值。
相對(duì)位移極差減少百分比越大,表明運(yùn)動(dòng)文胸減震效果越好[17]。
由圖7(a)可知,在4 km/h下,穿著Y-Ⅰ時(shí),X、Y方向乳房5個(gè)測(cè)量點(diǎn)位移幅度平均減小了約35%,其中B2和B3點(diǎn)在左右方向的相對(duì)位移極差減少百分比最大,B1、B4和B5點(diǎn)在前后方向的晃動(dòng)得到了更好的控制,尤其是B1點(diǎn)處;Z方向平均減小約25%,低于X、Y方向。而穿著Y-Ⅱ時(shí),B5點(diǎn)在Y方向減小幅度明顯低于其他測(cè)量點(diǎn),這是由于運(yùn)動(dòng)文胸對(duì)乳房的提拉和聚攏效果突出,乳房?jī)?nèi)側(cè)B5點(diǎn)處更加豐滿,導(dǎo)致其穩(wěn)定性降低;其余乳房測(cè)量點(diǎn)在各方向上的位移減少百分比均高于Y-Ⅰ近15%,減震效果顯而易見。
圖7(b)所顯示的Y-Ⅰ、Y-Ⅱ?qū)θ榉坎煌瑴y(cè)量點(diǎn)的減震作用與圖7(a)相似,Y-Ⅱ?qū)θ榉康谋Wo(hù)效果仍優(yōu)于Y-Ⅰ,且2款運(yùn)動(dòng)文胸均對(duì)乳房在Y方向上的晃動(dòng)起到了更好的控制作用,尤其是靠近乳房外側(cè)的B1、B2和B3點(diǎn)處,這說(shuō)明較強(qiáng)包裹性的運(yùn)動(dòng)文胸可一定程度上減小乳房的左右晃動(dòng)。但相較于4 km/h,在6 km/h速度下穿著Y-Ⅱ時(shí),Y方向位移減少百分比總體下降了近10%,這說(shuō)明在由快走(4 km/h)到慢跑(6 km/h)時(shí),乳房左右晃動(dòng)加劇,導(dǎo)致Y-Ⅱ?qū)θ榉康臏p震效果有所減弱。
由圖7(c)表明,在8 km/h時(shí),Y-Ⅱ?qū)θ榉?點(diǎn)的減震效果仍略優(yōu)于Y-Ⅰ。穿著Y-Ⅱ時(shí),乳房5點(diǎn)在X、Y方向上的相對(duì)位移極差減少百分比差別不大,均約為30%;Z方向約為20%。而穿著Y-Ⅰ時(shí),X方向上乳房5點(diǎn)相對(duì)位移極差減少百分比約在15%~25%不等,Y方向位于乳房外側(cè)的B3點(diǎn)最大,約為25%,B2最小;Z方向上乳房5點(diǎn)位移極差減小百分比基本一致,約為15%。進(jìn)一步對(duì)比在4 km/h和6 km/h速度下運(yùn)動(dòng)文胸對(duì)乳房的減震效果,8 km/h運(yùn)動(dòng)速度下穿著Y-Ⅰ或Y-Ⅱ時(shí),乳房各方向的位移減少百分比均降低了約10%~20%。由此可見,隨著運(yùn)動(dòng)速度的增加,乳房晃動(dòng)越加劇烈,而運(yùn)動(dòng)文胸對(duì)乳房運(yùn)動(dòng)的控制作用是有限的。
綜上可知,穿著運(yùn)動(dòng)文胸可對(duì)乳房運(yùn)動(dòng)起到較好的減震效果,且在任意速度下,高支撐強(qiáng)度文胸(Y-Ⅱ)均優(yōu)于中支撐強(qiáng)度文胸(Y-Ⅰ)對(duì)乳房的減震效果。另外在中低速運(yùn)動(dòng)時(shí),運(yùn)動(dòng)文胸對(duì)乳房左右晃動(dòng)和前后晃動(dòng)的控制效果突出,而當(dāng)速度增加到8 km/h時(shí),乳房運(yùn)動(dòng)幅度增大,運(yùn)動(dòng)文胸對(duì)乳房的減震作用會(huì)有所降低。因此,在運(yùn)動(dòng)時(shí)盡量選擇對(duì)乳房保護(hù)減震效果較好的運(yùn)動(dòng)文胸,尤其是在進(jìn)行高強(qiáng)度運(yùn)動(dòng)時(shí),以防止乳房在運(yùn)動(dòng)中損傷。對(duì)于設(shè)計(jì)者而言,應(yīng)對(duì)運(yùn)動(dòng)文胸對(duì)乳房的減震效果進(jìn)行充分研究測(cè)試,在研發(fā)運(yùn)動(dòng)文胸時(shí),不僅僅是通過(guò)增強(qiáng)文胸的緊身包裹度來(lái)提高文胸的支撐強(qiáng)度,還需更加注重文胸的結(jié)構(gòu)設(shè)計(jì),以進(jìn)一步提高文胸對(duì)乳房上下晃動(dòng)的控制作用。
3 結(jié) 論
為評(píng)價(jià)人體運(yùn)動(dòng)時(shí)運(yùn)動(dòng)速度及文胸支撐強(qiáng)度對(duì)乳房運(yùn)動(dòng)的影響,本文選取了3種支撐強(qiáng)度運(yùn)動(dòng)文胸,利用三維動(dòng)態(tài)捕捉系統(tǒng)獲取3名受試者在3種運(yùn)動(dòng)速度下走或跑的乳房位移,并通過(guò)建立軀干坐標(biāo)系得到乳房相對(duì)位移,分析后得出以下結(jié)論。
1) 乳房不同部位的相對(duì)位移極差存在不一致性,且其大小關(guān)系受速度和文胸類型的影響。說(shuō)明研究乳房運(yùn)動(dòng)時(shí)應(yīng)該測(cè)試多個(gè)部位,根據(jù)實(shí)際情況分析乳房運(yùn)動(dòng),不能一概而論地以乳頭點(diǎn)代表整個(gè)乳房運(yùn)動(dòng)。
2) 比較不同速度下的乳房三維運(yùn)動(dòng),3個(gè)方向位移幅度始終保持Z>Y>X;從4~6 km/h,乳房晃動(dòng)程度變化較小,而當(dāng)速度達(dá)到8 km/h時(shí),乳房各點(diǎn)在3個(gè)方向上運(yùn)動(dòng)均明顯增大,Z方向增幅約為X方向的2倍。
3) 通過(guò)比較不同支撐強(qiáng)度文胸為乳房的減震效果,發(fā)現(xiàn)同一運(yùn)動(dòng)速度下,穿著運(yùn)動(dòng)文胸可明顯減少乳房在3個(gè)方向上的位移幅度,對(duì)Y、X方向控制作用更突出;且隨著文胸支撐強(qiáng)度提高,對(duì)于乳房運(yùn)動(dòng)的減震效果增強(qiáng),同時(shí)對(duì)乳房整體運(yùn)動(dòng)的穩(wěn)定性也有所控制。
今后研究可進(jìn)一步增加文胸樣本量,擴(kuò)大研究群體,并可結(jié)合主觀衡量標(biāo)準(zhǔn),量化運(yùn)動(dòng)文胸對(duì)乳房的保護(hù)效果,以獲得對(duì)運(yùn)動(dòng)文胸市場(chǎng)的整體了解。這將有助于規(guī)范化設(shè)計(jì)開發(fā)高性能運(yùn)動(dòng)文胸,同時(shí)為消費(fèi)者合理選購(gòu)提供依據(jù)。
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Effects of movement velocity and bra support condition on breast movement
GUO Luqinga, WU Qiaoyingb
(a.School of Fashion Design & Engineering; b.School of International Education & Zhejiang International Institute of Fashion Technology,Zhejiang Sci-Tech University, Hangzhou 310018, China)
Abstract:
With the wide spread of the concept of national fitness, a growing number of people begin to actively participate in all kinds of fitness sports. Fast walking and running are the most simple and common ways of fitness in life, which are beloved by the majority of females. However, the breast consists of mammary gland, fat and skin, without the hard support of bones. So in the process of physical exercise, the breast will shake violently by gravity and inertia, and pull the skin and connective tissue, making people feel uncomfortable. Whats more, long-term improper exercise will lead to breast ligament strain or even sagging. Especially for females with large breasts, exercise brings more serious impact on breast movement. Sports bras are designed to control excessive breast movement. Although there are many available sports bras with different support conditions in the market, many females do not pay attention to the importance of correctly wearing the bra when exercising. It also shows that the research on the specific effect of sports bras on breast movement is still insufficient.
In order to explore the effects of bras with different support conditions on breast shaking during exercise, three females with a bra size of 75C and similar figures and three bras with different support conditions were selected, and the QUALISYS three-dimensional motion capture instrument was used to collect the displacement data of eight points of subjects at the movement velocities of 4 km/h (fast walking), 6 km/h (jogging) and 8 km/h (running). The eight points include the nipple point and the points at the upper, lower, left and right 5cm of the nipple point on the breast site, and the suprasternal notch point, the xiphoid process point and the left anterior inferior rib (the inferior edge of the tenth rib, aligned with the nipple point) on the torso. Among them, the breast displacement data of the five points obtained from the experiment are related to the movement of the breast itself and the motion of the human torso. Through the establishment of the coronal trunk coordinate system, the breast displacement data in the geodetic coordinate system are transformed into the relative displacement data in the new reference coordinate system, that is, the breast displacement relative to the torso. The difference between the maximum value and the minimum value of relative displacement within a stable period (5 s) is called relative displacement differentiation of the breast, and it is statistically analyzed by SPSS. The results show that with the increase of sports speed, the value of relative displacement differentiation of the breast increases in X, Y and Z directions, and when the movement speed increases from 6 km/h to 8 km/h, the increase of the relative displacement differentiation of the breast in Z direction is about twice as much as that in X direction. Compared with the ordinary bra, the high support sports bra can reduce the displacement of the breast by about 30%-50% in the X and Y directions and about 20%-40% in the Z direction, which is generally better than the medium support sports bra by about 5%-15%. For C cup females, wearing a high support sports bra during exercise can effectively reduce the three-dimensional movement amplitude of breasts, especially in the front-back and left-right directions.
Understanding the law of breast movement is helpful to standardize the design and development of high-performance sports bras, and at the same time provides a theoretical basis for reasonable purchase of consumers. In future studies, we can further increase the sample size of bras, expand the research group, and combine with subjective criteria to quantify the protective effect of sports bra on breasts, and get a full picture of the sports bra market.
Key words:
movement velocity; support intensity; breast shaking; 3D motion capture; torso coordinate system; relative displacement differentiation
收稿日期:
2022-07-01;
修回日期:
2023-03-03
基金項(xiàng)目:
浙江省科技廳基金項(xiàng)目(2021C35110)
作者簡(jiǎn)介:
郭路清(1997),女,碩士研究生,研究方向?yàn)榉b舒適性。通信作者:吳巧英,教授,bettywu2000@126.com。