Browsing by Author "Lombaard, Jean-Pierre"
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- ItemThe relationship between change of direction ability, acceleration and postural control of female university netball players(Stellenbosch : Stellenbosch University, 2018-12) Lombaard, Jean-Pierre; Venter, R. E.; Jaiyesimi, B. G.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Sport Science.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