The relationship between change of direction ability, acceleration and postural control of female university netball players

Lombaard, Jean-Pierre (2018-12)

Thesis (MScSportSc)--Stellenbosch University, 2018.

Thesis

ENGLISH ABSTRACT: The ability to change direction while at a high entry velocity is a highly valued athletic quality among many invasion team sports. In combination with an athlete’s cognitive perceptual ability, change of direction speed (CODS) is a vital component of effective and efficient agility manoeuvres. Due to its proposed link with agility performance, CODS is extensively researched. The relationship between CODS performance and other physical factors, such as acceleration and lower limb muscle qualities, have frequently been investigated. However, literature regarding the relationship between CODS ability and postural control (PC) is scarce. Maintaining control of the body’s centre of mass during a rapid directional change could potentially benefit the transition from deceleration to a subsequent acceleration. Recently the validity of many of the performance tests used to assess change of direction speed have been criticised. Many of the tests are suggested to favour athletes with superior acceleration abilities, thus masking the actual ability to change direction. The change of direction deficit is proposed as a practical method to truly measure an athlete’s ability to decelerate and subsequently accelerate in a new direction. The COD deficit was calculated as the difference between the best 505-CODS test time and a 10m straight-line sprint (SLS) time (COD deficit = CODS test time – 10m sprint). A low COD deficit indicates a short time was taken to change direction while at a high entry velocity. Using the 505-CODS test, the turning ability of each leg can be assessed. The primary aim of the study was to determine the relationship between CODS, acceleration and PC. The secondary aim was to evaluate the relationship between sprinting spatiotemporal gait variables with acceleration and change of direction speed. A total of 38 female university netball players (age = 19.5 ± 1.22) from the same club volunteered to participate in the study. The participants performed a series of tests to assess the bio-motor abilities. Each athlete performed three trials of a 20m SLS (with 5m, 10m and 20m split) and the three trials of the 505-CODS test, turning with both limbs. The best performances of the three trials were used. Single leg postural control (PC) was measured with the ISway accelerometery system using the modified Clinical Test for Sensory Interaction on Balance (mCTSIB) protocol. Gait variables were determined with timing gates and an Optogait system. Spearman’s correlation was used to explore the relationships between the variables. Moderate positive significant correlations were found between the total time of the 505-CODS test and the COD deficit (r=0.41-0.49; p<0.01). The 505-CODS test time was found to have a moderate to strong positive significant correlation to SLS times (r=0.37-0.56; p<0.01). In contrast, the COD deficit was found to have a moderate to strong inverse relationship with acceleration performances (r = -0.32 to -0.54; p<0.05). Both the 505-CODS test and the COD deficit were found to have no significant correlation with PC (p>0.05). Regarding the spatiotemporal gait variables, there was a moderate to large positive significant correlation between ground contact time (GCT) and SLS at all split times (r=0.38-0.60; p<0.05). Stride frequency (SF) had a moderate inverse significant correlation with the 20m split SLS time (r=-0.42; p=0.01). When compared to the 505-CODS test, there was a moderate inverse correlation with the SF and 505-CODS test time (r=-0.36 to -0.41; p<0.5). 505-CODS test turns with the dominant leg were shown to have a moderate positive significant correlation with GCT. In conclusion, using the COD deficit may be a practical tool for coaches to use to determine an athlete’s ability to change direction while at a high entry velocity. Faster university netball players demonstrated a longer COD deficit; thus, coaches are encouraged to enhance their athletes’ ability to rapidly decelerate in a controlled manner so that the time taken to turn is minimised. Key words: Change of direction speed, change of direction deficit, postural control, netball

AFFRIKAANSE OPSOMMING: Die vermoë om van rigting te verander met 'n hoë aanvangsnelheid is ‘n atletiese eienskap wat onder baie spansportsoorte, veral sportsoorte met indringingskenmerke, van hoë waarde geag word. In kombinasie met 'n atleet se kognitiewe waarnemingsvermoë, is rigtingveranderingspoed (RVS) 'n belangrike deel van effektiewe en doeltreffende ratsheidsmaneuvers. RVS is al deeglik ondersoek as gevolg van die veronderstelde skakel met ratsheidvermoë. Die verband tussen RVS-prestasie (performance) en ander fisieke faktore, soos versnelling en spierkrag van die onderste ledemate, word gereeld ondersoek. Literatuur oor die verband tussen RVS-vermoë en posturale beheer (PB) is egter skaars. Om in beheer te bly van die liggaam se middelpunt tydens 'n vinnige rigtingverandering kan moontlik die oorgang van spoedvermindering tot 'n daaropvolgende spoedversnelling vergemaklik. Onlangs is die geldigheid van baie van die prestasietoetse wat gebruik word om die verandering-van-rigting spoed te assesseer, gekritiseer. Daar word aangevoer dat heelwat van die toetse atlete met beter versnellingsvermoëns bevoordeel. Sodoende word die werklike vermoë om rigting te verander, verbloem. Die verandering-van-rigting-tekort (VVRT) word voorgestel as 'n praktiese metode om 'n atleet se ware vermoë om te versnel en daarna in 'n nuwe rigting te versnel, te meet. Die VVRT word bereken as die verskil tussen die beste 505-RVS toetstyd en 'n 10m reguitlyn naellooptyd (VVRT = RVS toetstyd - 10m sprint). 'n Lae VVRT dui aan dat dit 'n kort tydjie geneem het om rigting te verander tydens 'n hoë beginsnelheid. Met behulp van die 505-RVS toets kan die draaivermoë van elke been bepaal word. Die primêre doel van die studie was om die verband tussen RVS, versnelling en PB te bepaal. Die sekondêre doelwit was om die verwantskap tussen tyd-ruimtelike hardloopveranderlikes te evalueer met versnelling en RVS. Altesaam 38 vroulike universiteit-netbalspelers (ouderdom = 19.5 ± 1.22) van dieselfde klub het vrywillig aan die studie deelgeneem. Die deelnemers het 'n reeks toetse uitgevoer om hul bio-motoriese vermoëns te assesseer. Elke atleet het drie herhalings van 'n 20m SLS (met 5m, 10m en 20m breuke) uitgevoer en drie toetse van die 505-CODS toets, draai op albei bene. Die beste telling van die drie herhalings is gebruik. Enkelbeen posturale beheer (PB) is gemeet met die ISway versnellingsmeterstelsel met behulp van die gewysigde kliniese toetse vir sensoriese interaksie vir balans (mCTSIB) protokol. Spearman se korrelasie is gebruik om die verhoudings tussen die veranderlikes te ondersoek. ‘n Matige, positief beduidende korrelasie is gevind tussen die totale tyd van die 505-RVS toets en die RV tekort (r = 0,41-0,49; p <0,01). Die 505-CODS toetstyd het bevind dat 'n matige tot sterk positiewe beduidende korrelasie bestaan met SLS-tye (r = 0,37-0,56; p <0,01). In teenstelling hiermee is bevind dat die VVRT 'n matige tot sterk omgekeerde verhouding met versnellingsprestasies (r = -0.32 tot -0.54; p <0.05) gehad het. Beide die 505-RVS-toets en die VVRT het geen beduidende korrelasie met PB (p> 0.05) gehad nie. Met betrekking tot die tyd-ruimtelike hardloopveranderlikes was daar 'n matige tot groot positief beduidende korrelasie tussen grondkontaktyd (ground contact time, GCT) en SLS op alle fraksietye (r = 0,38-0,60; p <0,05). Frekwensie van treë (Stride frequency, SF) het 'n matige omgekeerde beduidende korrelasie met die 20m fraksie SLS tyd (r = -0.42; p = 0.01). In vergelyking met die 505-CODS toets was daar 'n matige omgekeerde korrelasie met die SF en 505-CODS toetstyd (r = -0.36 tot -0.41; p <0.5). 505-CODS toetsdraaie op die dominante been het getoon dat dit 'n matige positiewe beduidende korrelasie met GCT het. Ter afsluiting, die gebruik van die VVRT kan 'n praktiese hulpmiddel wees. Afrigters kan dit gebruik om 'n atleet se vermoë te bepaal om rigting te verander teen 'n hoë aanvangsnelheid. Vinniger universiteitsvlak netbalspelers het 'n langer VVRT getoon. Daarom word afrigters aangemoedig om hul atlete se vermoë te verbeter om vinnig in gekontroleerde omstandighede te versnel om sodoende omdraaityd te verminder. Sleutelwoorde: Verandering-van-rigting spoed, verandering-van-rigting tekort, postuurbeheer, netbal

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