Graham-Smith P, Atkinson L, Barlow R, and Jones P. Braking ... Christopher Thomas, Thomas Dos'Santos, Irene Kyriakidou, Matthew Cuthbert, Cara Fields and ...
A comparison of braking characteristics between modified and traditional 505 change of direction tasks The 8 Annual Strength and in female netball players: An exploratory study Conditioning Student Conference th
Christopher Thomas, Thomas Dos’Santos, Irene Kyriakidou, Matthew Cuthbert, Cara Fields and Paul A. Jones Centre for Health Sciences Research, University of Salford
Introduction Modified (M505) and traditional (T505) 505 change of direction (COD) tests are commonly used to assess both performance and non-contact anterior cruciate ligament injury risk factors in athletes (1,2). Most biomechanical studies into changing direction focus on final contact (‘turn’), but little is known about the role of penultimate contact. Previous research (1-3) has highlighted the importance of pre-steps or penultimate contact during sharp (>90º) COD manoeuvres involving a >10m approach. However, no research has examined the influence of approach distance in this regard. The aim of this study was to examine whether approach distance influences braking strategy by comparing braking characteristics between M505 and T505 COD tasks. Method • The study was approved by the University’s ethics committee. • Ten female netball players (mean ± SD, age: 18.8 ±1.5 years, height: 1.71 ± 0.05 m, mass: 65.1 ± 5.1 kg) performed 6 trials each of M505 and T505, turning with the left (L) and right (R) limbs. • For each trial, three-dimensional motion data using Qualisys Oqus 7 infrared cameras (240 Hz) operating through Qualisys Track Manager software v2.14 and GRF data from two AMTI force platforms (1200 Hz) were collected. • This arrangement allowed data to be collected for both penultimate (PEN) & final (FIN) contact during both tasks (Fig 1). • Joint coordinate and force data were smoothed with a Butterworth low pass digital filter with cut-off frequencies of 12 and 25 Hz, respectively. • Peak GRF’s, knee and hip joint angles and moments were determined during the weight acceptance phase (VGRF >20 N to maximum knee flexion) of each contact. • A 2 × 2 factorial ANOVA for the factors of contact (PEN vs. FIN) and task (M505 vs. T505) was used to compare each dependent variable.
a
b
• Statistically significant (p < 0.05) main effects were observed between contacts on the right limb for peak vertical GRF (η² = 0.79), hip flexion (η² = 0.93), knee flexion (η² = 0.79) and internal knee extensor moments (η² = 0.58).
• No significant (p > 0.05) interactions between contacts (PEN and FIN) and task (M505R and T505R) were observed for peak vertical GRF (η2 = 0.04), horizontal GRF (η2 = 0.20), hip flexion (η2 = 0.02), knee flexion (η2 = 0.09), internal hip (η2 = 0.14) and knee (η2 = 0.18) extensor moments. Table 1. Mean ± SD of peak forces, knee & hip joint angles & moments during penultimate (PEN) and final (FINAL) contact of M505 and T505 with left (L) limb.
Variable
PEN
FIN
M505L
T505L
M505L
T505L
Peak VGRF (BW)
2.99 ± 0.39
3.49 ± 1.03
2.06 ± 0.27
2.17 ± 0.40
Peak HGRF (BW)
-2.11 ± 0.35
-2.51 ± 0.89
-1.70 ± 0.28
-1.75 ± 0.39
78 ± 9
78 ± 13
53 ± 10
50 ± 8
3.36 ± 1.07
3.11 ± 1.35
2.76 ± 0.93
2.79 ± 1.12
91 ± 16
92 ± 19
66 ± 9
65 ± 10
4.15 ± 0.93
4.05 ± 1.17
2.08 ± 0.38
1.90 ± 0.37
Peak Hip Flexion Angle (°) Peak Hip Ext Mom (Nm·kgˉ¹) Peak Knee Flexion Angle (°) Peak Knee Ext Mom (Nm·kgˉ¹)
Table 2. Mean ± SD of peak forces, knee & hip joint angles & moments during penultimate (PEN) and final (FINAL) contact of M505 and T505 with right (R) limb.
Variable
PEN
FIN
M505R
T505R
M505R
T505R
Peak VGRF (BW)
2.82 ± 0.80
3.03 ± 0.58
2.09 ± 0.26
2.20 ± 0.28
Peak HGRF (BW)
-1.88 ± 0.76
-2.17 ± 0.56
-1.72 ± 0.26
-1.81 ± 0.24
Peak Hip Flexion Angle (°)
81 ± 15
79 ± 18
51 ± 13
49 ± 14
Peak Hip Ext Mom (Nm·kgˉ¹)
3.36 ± 1.07
3.11 ± 1.35
2.76 ± 0.93
2.79 ± 1.12
Peak Knee Flexion Angle (°)
91 ± 16
92 ± 18
66 ± 9
65 ± 10
3.85 ± 1.26
4.06 ± 1.33
2.62 ± 0.47
2.58 ± 0.36
Peak Knee Ext Mom (Nm·kgˉ¹)
*VGRF = vertical ground reaction force; HGRF = horizontal ground reaction force; Ext Mom = extensor moment.
Figure 1. Qualisys motion analysis and AMTI force platforms used to derive braking forces and internal joint moments in the PEN (b) and FIN contact (a).
Summary and Conclusion This study has been unable to demonstrate that approach distance affects braking strategy of a 180°COD task. However, the results do illustrate meaningful differences in braking strategy between PEN and FIN contacts, regardless of the task performed; illustrating the importance of PEN contact in COD tasks >90º. References
Results • Statistically significant (p < 0.05) main effects were observed between contacts on the left limb for peak vertical GRF (η² = 0.63), horizontal GRF (η² = 0.81), hip flexion (η² = 0.92), knee flexion (η² = 0.75) and internal knee extensor moments (η² = 1. Graham-Smith P, Atkinson L, Barlow R, and Jones P. Braking characteristics and load distribution in 180 degree turns. Presented 0.85). at The Proceedings of the 5th annual UKSCA conference, 2009. • No significant (p > 0.05) interactions between contacts (PEN and FIN ) and task (M505L and T505L) were observed for peak vertical 2. Jones PA, Herrington L, and Graham-Smith P. Braking characteristics during cutting and pivoting in female soccer players. J Electromyogr GRF (η² = 0.12), horizontal GRF (η² = 0.21), hip flexion (η² = 0.08), Kinesiol, 2016. knee flexion (η2 = 0.05), internal hip (η2 = 0.09) and knee (η2 = 3. Nedergaard NJ, Kersting U, and Lake M. Using accelerometry to 0.01) extensor moments. quantify deceleration during a high-intensity soccer turning manoeuvre. J Sports Sci 32: 1897-1905, 2014.
