{"id":21611,"date":"2018-05-25T07:54:00","date_gmt":"2018-05-25T06:54:00","guid":{"rendered":"https:\/\/axkid.com\/rear-facing-myths-their-legs-are-at-risk-of-breaking\/"},"modified":"2025-10-02T12:52:08","modified_gmt":"2025-10-02T11:52:08","slug":"myty-o-sedackach-smerujicich-dozadu-hrozi-jim-zlomenina-nohou","status":"publish","type":"post","link":"https:\/\/axkid.com\/cz\/vyzkum-a-inovace\/myty-o-sedackach-smerujicich-dozadu-hrozi-jim-zlomenina-nohou\/","title":{"rendered":"M\u00fdty o seda\u010dk\u00e1ch sm\u011b\u0159uj\u00edc\u00edch dozadu: Hroz\u00ed jim zlomenina nohou"},"content":{"rendered":"\n

Mezi r\u016fzn\u00fdmi m\u00fdty, kter\u00e9 se t\u00fdkaj\u00ed prodlou\u017een\u00fdch autoseda\u010dek sm\u011b\u0159uj\u00edc\u00edch proti sm\u011bru j\u00edzdy<\/a>, je jeden, kter\u00fd je obzvl\u00e1\u0161t\u011b znepokojuj\u00edc\u00ed, proto\u017ee se net\u00fdk\u00e1 pohodl\u00ed, ale bezpe\u010dnosti. Jedn\u00e1 se o obavu, \u017ee p\u0159i cestov\u00e1n\u00ed proti sm\u011bru j\u00edzdy a s men\u0161\u00edm prostorem pro nohy by se tyto mohly p\u0159i nehod\u011b zlomit. Nakolik je tato roz\u0161\u00ed\u0159en\u00e1 obava opodstatn\u011bn\u00e1?<\/strong><\/p>\n\n\n\n


Co m\u016f\u017ee p\u0159i n\u00e1razu zlomit d\u00edt\u011bti nohy?<\/strong><\/p>\n\n\n\n

To je prvn\u00ed bod, kter\u00fd bychom m\u011bli objasnit. Jak by k zlomenin\u011b mohlo doj\u00edt? No, t\u00edm nejviditeln\u011bj\u0161\u00edm zp\u016fsobem: n\u00e1razem nohou na tvrd\u00fd povrch.<\/p>\n\n\n\n

P\u0159i nehod\u011b nebo n\u00e1hl\u00e9m brzd\u011bn\u00ed jsou v\u0161echny prvky uvnit\u0159 vozidla vymr\u0161t\u011bny dop\u0159edu setrva\u010dnost\u00ed, kterou m\u011bly v okam\u017eiku n\u00e1razu, a to jak p\u0159edm\u011bty, kter\u00e9 ve vozidle p\u0159epravujeme, tak i na\u0161e t\u011bla.<\/p>\n\n\n\n

P\u0159i n\u00e1razu se proto nohy v\u017edy pohybuj\u00ed ve stejn\u00e9m sm\u011bru jako hlava: sm\u011brem k p\u0159edn\u00ed \u010d\u00e1sti vozu. V\u00edme ji\u017e, \u017ee zadn\u00ed \u010d\u00e1st hlavy je zaji\u0161t\u011bna a chr\u00e1n\u011bna op\u011bradlem sedadla a nen\u00ed vystavena \u017e\u00e1dn\u00e9mu tahu, ale co se stane s nohama?<\/p>\n\n\n\n

Kdy\u017e jsou nohy ovlivn\u011bny stejnou setrva\u010dnost\u00ed jako ostatn\u00ed \u010d\u00e1sti vozidla, oh\u00fdbaj\u00ed se sm\u011brem k trupu a op\u011bt se natahuj\u00ed. Pokud se pod\u00edv\u00e1me na n\u011bkter\u00e1 videa z n\u00e1razov\u00fdch test\u016f nebo crash test\u016f, m\u016f\u017eeme vid\u011bt, \u017ee nohy p\u0159i j\u00edzd\u011b proti sm\u011bru j\u00edzdy zpo\u010d\u00e1tku nenar\u00e1\u017eej\u00ed na \u017e\u00e1dn\u00fd povrch. P\u0159i zp\u011btn\u00e9m pohybu by se nohy zlomily pouze v p\u0159\u00edpad\u011b, \u017ee by do\u0161lo tak\u00e9 k posunut\u00ed seda\u010dky, k \u010demu\u017e u seda\u010dek sm\u011b\u0159uj\u00edc\u00edch dozadu nedoch\u00e1z\u00ed, proto\u017ee jsou vybaveny speci\u00e1ln\u00edmi bezpe\u010dnostn\u00edmi prvky, kter\u00e9 tomu zabra\u0148uj\u00ed, jako je protin\u00e1razov\u00e1 ty\u010d nebo spodn\u00ed \u00fachyty (popruhy, kter\u00e9 p\u0159ipev\u0148uj\u00ed seda\u010dku ke dnu vozidla).<\/p>\n\n\n\n

Ale nen\u00ed to \u010dast\u00e9 p\u0159i j\u00edzd\u011b v pozici z\u00e1dy ke sm\u011bru j\u00edzdy?<\/strong><\/p>\n\n\n\n

Zlomenina doln\u00ed kon\u010detiny je p\u0159i j\u00edzd\u011b v p\u0159edn\u00edm sm\u011bru mnohem pravd\u011bpodobn\u011bj\u0161\u00ed a \u010dast\u011bj\u0161\u00ed ne\u017e v opa\u010dn\u00e9m sm\u011bru, a d\u016fvod je jednoduch\u00fd: v tomto p\u0159\u00edpad\u011b nohy p\u0159i n\u00e1razu prudce dopadnou na p\u0159edn\u00ed sedadlo. Jeliko\u017e se nejv\u00edce zaj\u00edm\u00e1me o poran\u011bn\u00ed kr\u010dn\u00ed p\u00e1te\u0159e, soust\u0159ed\u00edme se v\u011bt\u0161inou pouze na to, co se d\u011bje v oblasti hlavy a krku, ale pokud se pod\u00edv\u00e1me na n\u00e1razov\u00fd test v autoseda\u010dce sm\u011b\u0159uj\u00edc\u00ed dop\u0159edu, uvid\u00edme, jak nohy v\u00fdrazn\u011b p\u0159esahuj\u00ed linii n\u00e1razu. Co je to linie n\u00e1razu? Je to bod, kter\u00fd definuje, kde se nach\u00e1z\u00ed p\u0159edn\u00ed sedadlo vozidla. To znamen\u00e1, \u017ee v\u0161e, co p\u0159esahuje tuto \u010dervenou \u010d\u00e1ru, bude m\u00edt p\u0159\u00edm\u00fd dopad na p\u0159edn\u00ed sedadlo. Je d\u016fle\u017eit\u00e9 v\u011bd\u011bt, \u017ee v homologa\u010dn\u00edch testech pouze hlava nep\u0159esahuje linii n\u00e1razu. Nohy, jak vid\u00edme, ji p\u0159esahuj\u00ed.<\/p>\n\n\n\n

Zlomila by tedy trak\u010dn\u00ed s\u00edla nohy d\u00edt\u011bte sed\u00edc\u00edho v protism\u011bru stejn\u011b jako zlomila krk d\u00edt\u011bte sed\u00edc\u00edho ve sm\u011bru j\u00edzdy?<\/strong><\/p>\n\n\n\n

Ne, proto\u017ee neexistuje \u017e\u00e1dn\u00e1 dist\u00e1ln\u00ed \u201etahov\u00e1\u201c s\u00edla. V autoseda\u010dk\u00e1ch sm\u011b\u0159uj\u00edc\u00edch dop\u0159edu se hlava d\u00edky sv\u00e9 hmotnosti st\u00e1v\u00e1 projektilem, kter\u00fd je vymr\u0161t\u011bn dop\u0159edu setrva\u010dnost\u00ed vozidla a zp\u016fsobuje siln\u00fd tah na krk, jako olovnice, kter\u00e1 t\u00e1hne lano a nap\u00edn\u00e1 ho s rizikem jeho po\u0161kozen\u00ed. Pr\u00e1v\u011b tento tah m\u016f\u017ee zp\u016fsobit poran\u011bn\u00ed kr\u010dn\u00ed p\u00e1te\u0159e a p\u00e1te\u0159e. P\u0159i sezen\u00ed sm\u011brem dozadu se v\u0161ak nohy \u201esmr\u0161\u0165uj\u00ed\u201c sm\u011brem k zbytku t\u011bla. Nejsou ta\u017eeny od konce (chodidel), co\u017e by p\u016fsobilo silou na p\u00e1nev; naopak se oh\u00fdbaj\u00ed a pak se op\u011bt natahuj\u00ed, p\u0159i\u010dem\u017e p\u0159i pohybu dozadu maj\u00ed mnohem ni\u017e\u0161\u00ed kinetickou energii. Krom\u011b toho jsou rozhoduj\u00edc\u00ed rozd\u00edly mezi jednotliv\u00fdmi strukturami. Hlava dvoulet\u00e9ho d\u00edt\u011bte v\u00e1\u017e\u00ed asi 2,5 kg a kr\u010dn\u00ed oblast je nezral\u00e1 a slab\u00e1. U doln\u00edch kon\u010detin plat\u00ed, \u017ee \u010d\u00edm dist\u00e1ln\u011bj\u0161\u00ed je kloub, t\u00edm men\u0161\u00ed m\u00e1 v\u00e1hu a velikost, tak\u017ee t\u00e9m\u011b\u0159 nevyv\u00edj\u00ed tah na proxim\u00e1ln\u00ed, siln\u011bj\u0161\u00ed, v\u011bt\u0161\u00ed a t\u011b\u017e\u0161\u00ed klouby. I kdyby tomu tak bylo, n\u00e1raz s tak vysok\u00fdmi setrva\u010dn\u00fdmi silami, kter\u00e9 by zp\u016fsobily poran\u011bn\u00ed doln\u00ed kon\u010detiny p\u0159i j\u00edzd\u011b v pozici proti sm\u011bru j\u00edzdy, by vedl k mnohem v\u00e1\u017en\u011bj\u0161\u00edm poran\u011bn\u00edm krku v pozici po sm\u011bru j\u00edzdy, kter\u00e1 jsou obecn\u011b nevratn\u00e1 a v n\u011bkter\u00fdch p\u0159\u00edpadech dokonce smrteln\u00e1. Co bychom up\u0159ednostnili p\u0159i ochran\u011b na\u0161ich d\u011bt\u00ed: mo\u017enou zlomeninu nohy nebo vnit\u0159n\u00ed dekapitaci?<\/p>\n\n\n\n

Ale mezi nohama a sedadlem je m\u00e9n\u011b m\u00edsta, nen\u00ed to nebezpe\u010dn\u00e9?<\/strong><\/p>\n\n\n\n

Mal\u00fd prostor mezi nohama a zadn\u00edm sedadlem automobilu by byl v\u00fdznamn\u00fd nebo nebezpe\u010dn\u00fd pouze v p\u0159\u00edpad\u011b, \u017ee by setrva\u010dnost prudce tla\u010dila nohy t\u00edmto sm\u011brem a narazila do n\u00e1s p\u0159i couv\u00e1n\u00ed ur\u010ditou rychlost\u00ed.
\u00a0<\/strong><\/p>\n\n\n\n

Co se stane, kdy\u017e bude auto rozdrceno?<\/strong><\/p>\n\n\n\n

V p\u0159\u00edpad\u011b, \u017ee n\u00e1raz zp\u016fsob\u00ed kolaps vozidla nebo dojde k vniknut\u00ed, m\u016f\u017ee doj\u00edt ke stla\u010den\u00ed prostoru mezi nohama a zadn\u00edm sedadlem (stejn\u011b jako v p\u0159\u00edpad\u011b prostoru mezi na\u0161imi nohama a p\u0159ihr\u00e1dkou na rukavice ve vozidle, kdy\u017e cestujeme na sedadle spolujezdce) a zp\u016fsobit poran\u011bn\u00ed doln\u00edch kon\u010detin. Stejn\u00e1 situace by v\u0161ak byla je\u0161t\u011b z\u00e1va\u017en\u011bj\u0161\u00ed p\u0159i j\u00edzd\u011b \u010delem k sm\u011bru j\u00edzdy, proto\u017ee by se cel\u00e1 \u017eidle posunula dop\u0159edu, \u010d\u00edm\u017e by zmizela vzd\u00e1lenost mezi t\u011blem a p\u0159edn\u00edm sedadlem a do\u0161lo by k v\u00e1\u017en\u011bj\u0161\u00edm zran\u011bn\u00edm.<\/p>\n\n\n\n

Zdroj: Marta Erill, fyzioterapeutka ve spolupr\u00e1ci s Ana Irene Urbieta Quiroga, profesorka fyzik\u00e1ln\u00edch v\u011bd, Universidad Complutense de Madrid<\/em><\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

Mezi r\u016fzn\u00fdmi m\u00fdty, kter\u00e9 se t\u00fdkaj\u00ed prodlou\u017een\u00fdch autoseda\u010dek sm\u011b\u0159uj\u00edc\u00edch proti sm\u011bru j\u00edzdy, je jeden, kter\u00fd je obzvl\u00e1\u0161t\u011b znepokojuj\u00edc\u00ed, proto\u017ee se… <\/br>P\u0159e\u010d\u00edst cel\u00fd p\u0159\u00edsp\u011bvek<\/a><\/p>\n","protected":false},"author":29,"featured_media":381,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_seopress_robots_primary_cat":"none","_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","_seopress_analysis_target_kw":"","content-type":"","_relevanssi_hide_post":"","_relevanssi_hide_content":"","_relevanssi_pin_for_all":"","_relevanssi_pin_keywords":"","_relevanssi_unpin_keywords":"","_relevanssi_related_keywords":"","_relevanssi_related_include_ids":"","_relevanssi_related_exclude_ids":"","_relevanssi_related_no_append":"","_relevanssi_related_not_related":"","_relevanssi_related_posts":"21671,21612,21617,21672,21619,21626","_relevanssi_noindex_reason":"","editor_notices":[],"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[423],"tags":[],"class_list":["post-21611","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-vyzkum-a-inovace"],"acf":[],"jetpack_featured_media_url":"https:\/\/axkid.com\/app\/uploads\/a456cc06-rearfacing.jpg","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/axkid.com\/cz\/wp-json\/wp\/v2\/posts\/21611","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/axkid.com\/cz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/axkid.com\/cz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/axkid.com\/cz\/wp-json\/wp\/v2\/users\/29"}],"replies":[{"embeddable":true,"href":"https:\/\/axkid.com\/cz\/wp-json\/wp\/v2\/comments?post=21611"}],"version-history":[{"count":5,"href":"https:\/\/axkid.com\/cz\/wp-json\/wp\/v2\/posts\/21611\/revisions"}],"predecessor-version":[{"id":848028,"href":"https:\/\/axkid.com\/cz\/wp-json\/wp\/v2\/posts\/21611\/revisions\/848028"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/axkid.com\/cz\/wp-json\/wp\/v2\/media\/381"}],"wp:attachment":[{"href":"https:\/\/axkid.com\/cz\/wp-json\/wp\/v2\/media?parent=21611"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/axkid.com\/cz\/wp-json\/wp\/v2\/categories?post=21611"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/axkid.com\/cz\/wp-json\/wp\/v2\/tags?post=21611"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}