Risk factors for hamstring strain injuries during sprint

Uvod: Preobremenitvene poškodbe fleksorjev kolena spadajo med najpogostejše športne poškodbe, ki imajo visoko stopnjo ponovljivosti. V zadnjih desetletjih številčno niso upadle, kar kaže na naše trenutno slabše razumevanje teh poškodb in njihovih dejavnikov tveganja. Namen: Namen diplomskega dela je predstaviti potencialne dejavnike tveganja za preobremenitvene poškodbe fleksorjev kolena pri sprintu. Ugotoviti želimo, kako kinematika trupa in fleksorjev kolena med sprintom vpliva na njihovo povečano obremenitev. Metode dela: V diplomskem delu je bila uporabljena metoda pregleda literature. Pri iskanju je bil uporabljen časovni okvir, in sicer od leta 2007 do 2017, in članki, ki so preučevali kinematiko trupa in fleksorjev kolena med sprintom. Literatura je bila iskana v angleškem jeziku v podatkovni bazi PubMed pod ključnimi besedami hamstring injuries AND risk factors AND sprinting. V pregled je bilo vključenih sedem študij. Rezultati: Dve študiji sta preučevali vpliv stabilnosti jedra telesa na pojavnost preobremenitvene poškodbe fleksorjev kolena, ostalih pet je raziskovalo parametre, ki vplivajo na povečano obremenitev fleksorjev kolena. Nagib medenice anteriorno in večje prsno odklanjanje v fazi zamaha ter manjša elektromiografska aktivnost mišice gluteus maximus in trupa so prisotni pri preiskovancih, ki so v času študije prvič utrpeli preobremenitveno poškodbo fleksorjev kolena. Mišično-kitna dolžina fleksorjev kolena je v fazi pospeševanja v primerjavi s fazo maksimalne hitrosti večja pri dotiku pete s podlago in pri dvigu prstov s podlage, a se v obeh fazah maksimalna mišično-kitna dolžina pojavi v pozni fazi zamaha. Elektromiografska aktivnost fleksorjev kolena doseže izbruh v pozni fazi zamaha in v začetni fazi opore. Razprava in zaključek: Zaradi anatomskih povezav fleksorjev kolena s proksimalnimi stabilizacijskimi strukturami večje prsno odklanjanje in nezadostna aktivacija globokih mišic povečata tveganje za preobremenitveno poškodbo fleksorjev kolena. Povečana obremenitev na fleksorje kolena se pojavi tudi v primeru povečanega nagiba medenice anteriorno, ki poveča razteg fleksorjev kolena, in zmanjšana aktivnost mišice gluteus maximus, ki prenese obremenitve na sinergistične fleksorje kolena. Mišični razteg predstavlja pomemben dejavnik tveganja za preobremenitveno poškodbo fleksorjev kolena, zato pozna faza zamaha in dotik pete s podlago v fazi pospeševanja predstavljata tvegan trenutek. K povečanemu tveganju pomembno pripomore tudi elektromiografska aktivnost fleksorjev kolena, a je njena funkcija predvsem preprečitev prekomernega mišičnega raztega.Introduction: Hamstring injuries are the most common injuries in sports that have high reinjury rate. High rates of injuries in the past decades have not declined. It is suggested that our current understanding of hamstring injuries and reinjury risk is incomplete. Purpose: The purpose of the thesis is to introduce possible risk factors for hamstring injuries during sprint. We want to objectify the importance of trunk and hamstring kinematics during sprint in hamstring injury susceptibility. Methods: The research was obtained using the online database PubMed. Seven articles in the English language were included in the literature review. They were published between the years 2007 and 2017 and they discussed trunk and hamstring kinematics during sprint. The articles were found under the following keywords: hamstring injuries AND risk factors AND sprinting. Results: Two research studies examined how trunk stability influences hamstring injury susceptibility and five research studies dealt with parameters that increase load on hamstring muscles. Hamstring injury occurrence is associated with higher levels of anterior pelvic tilting and thoracis side bending throughout the swing phase of sprinting and with lower amounts of gluteal and trunk muscle activity. The musculotendon length of hamstring muscles at foot strike and toe-off is significantly greater during acceleration phase than during high speed sprinting. During both phases the maximal musculotendon length occurs in the late swing phase. Electromiography activity of hamstring muscles outbursts in the late swing phase and early stance phase. Discussion and conclusion: Because of the anatomical connections between hamstring muscles and proximal stabilizing structures, higher levels of thoracis side bending and insufficient deep musculature activation increase hamstring injury susceptibility. Load on hamstring muscles is increased in case of increased anterior pelvic tilt that influences the lengthening of hamstring muscles and in case of insufficient electromiography activity of gluteal muscle that influences the hamstring muscles activity because of their synergistic coactivation. Musculotendon length is an important risk factor for hamstring injury. Late swing phase and foot strike in acceleration phase are therefore risky moments for hamstring injury. Electromiography activity of hamstring muscles also importantly contributes to hamstring injury but its task in function is mostly to prevent excessive musculotendon strain