Journal of Sports Sciences
ISSN: 0264-0414 (Print) 1466-447X (Online) Journal homepage: http://www.tandfonline.com/loi/rjsp20
Day 2. Posters – Biomechanics and Motor Behaviour To cite this article: (2015) Day 2. Posters – Biomechanics and Motor Behaviour, Journal of Sports Sciences, 33:sup1, s81-s84, DOI: 10.1080/02640414.2015.1110332 To link to this article: http://dx.doi.org/10.1080/02640414.2015.1110332
Published online: 25 Nov 2015.
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Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=rjsp20 Download by: [Laurentian University]
Date: 16 March 2016, At: 09:44
Journal of Sports Sciences, 2015 Vol. 33, Supplement 1, s81–s84, http://dx.doi.org/10.1080/02640414.2015.1110332
Day 2. Posters – Biomechanics and Motor Behaviour
D2.P04. Sex differences in maximum and explosive voluntary torque of the knee extensors and plantar flexors FEARGHAL BEHAN1,2*, MATTHEW PAIN1 & JONATHAN FOLLANDa,b Loughborough University; 2ARUK Centre for Sport, Exercise and Osteoarthritis *Corresponding author: [email protected]
Downloaded by [Laurentian University] at 09:44 16 March 2016
1
Explosive muscular force production is considered important for sport performance and injury prevention (Tillin and Folland, 2013, European Journal of Applied Physiology, 114, 365–374). Females have greater incidence of anterior cruciate knee ligament injuries than males and sex discrepancies in explosive force may be a contributory factor that requires further investigation. The aim of this study was to investigate sex differences in maximum voluntary torque (MVT) and explosive voluntary torque (EVT) in the knee extensors (KE) and plantar flexors (PF). Following ethical approval, neuromuscular performance of 21 untrained males (mean ± SD; age: 25.1 ± 4.9 years, height: 1.81 ± 0.09 m, mass: 81.4 ± 10.0 kg) and 20 untrained females (22.4 ± 3.1 years, 1.67 ± 0.06 m, 65.3 ± 9.2 kg) was assessed during maximal and explosive isometric knee extension and plantar flexion contractions. MVT was measured during maximum voluntary contractions and EVT at 25, 50, 75, 100, 150 and 200 ms from force onset during explosive contractions. A two-way repeated measures ANOVA and student’s independent t-tests with a Bonferroni correction were undertaken. Males were significantly stronger in KE (302 ± 43 N · m vs. 160 ± 31 N · m, P < 0.01) and PF (282 ± 56 N · m vs. 181 ± 36 N · m, P < 0.01) than females and displayed significantly greater EVT at all time-points in KE (P < 0.01) and from 50 to 200 ms in PF (P < 0.05). Males also had significantly greater MVT and EVT at all time-points in KE (MVT P < 0.01, EVT P < 0.05) and at 25 and 100–200 ms in PF (MVT P < 0.01, EVT P < 0.05) when force was normalised to body mass. However, when EVT was normalised to MVT there was no significant difference between the sexes (P = 0.372). Pooled data showed significant correlations between KE and PF MVT (absolute: r = 0.832, P < 0.01) and © 2015 Taylor & Francis
EVT from 50 to 200 ms (absolute: r = 0.488–0.763, P < 0.01; relative to MVT: r = 0.353–0.764, P < 0.05). Greater male MVT appears to explain their superior explosive force production in KE and PF in agreement with previous KE research (Hannah et al., 2012, Experimental Physiology, 97, 618–629). Additionally, KE and PF MVT and EVT appear moderately–strongly correlated. Future injury prevention programmes should emphasise increasing female absolute MVT as both genders appear to possess a similar ability to express their available force-generating capacity in an explosive manner.
D2.P05. The dose-response effects of dissociation training on measures of neuromuscular control during performance screening in male youth footballers ROBERT M. BURGE1*, GARY DAVENPORT2, STEPHEN TAYLOR2, JONATHAN D. HUGHES1 & MARK DE STE CROIX1 1
University of Gloucestershire; 2Bristol City Football Club *Corresponding author: [email protected] @RMBurge Movement screens purportedly identify compensatory kinematics that predispose athletes to injury (Kiesel, Plisky, and Butler, 2011,Scandinavian Journal of Medicine and Science in Sports, 21, 287–292). The efficacy of assessing select competencies and prescribing remedial training based on screen outcomes however remains equivocal. The Foundation Performance Matrix Screen© (FPMS) supposedly profiles injury risk, subsequently directing its independent motor control Dissociation Training (DT) (Mottram and Comerford, 2008, Physical Therapy in Sport, 9, 40–51). However, there appears to be no research evidencing that DT can improve FPMS score or reduce injury. The dose-response to DT therefore remains to be established. With institutional ethics approval, elite U15/ 16 and U17/18 male academy footballers comprised Group 1 (n = 6) (G1) and Group 2 (n = 8) (G2),
Downloaded by [Laurentian University] at 09:44 16 March 2016
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respectively. G1 performed DT 1x week while G2 performed DT 3x week over 8 weeks. Centre of pressure (CoP) total, anterior-posterior (X) and medial-lateral (Y) displacements (cm), sway velocity (cm · s−1) and ellipse area (cm2) were recorded from participants’ non-dominant leg during a single leg stance test (SLST) and Y balance test™ (YBT). Force platform time to stabilisation (TTS), peak vertical ground reaction force (PVGRF) and loading rates were recorded from a 20-cm bilateral drop jump landing (DJL). The FPMS and YBT were scored according to respective guidelines. All tests were performed barefoot. Cohen’s d effect size (ES) was calculated from differences in means. Small ES for G1 (ES −0.180; 95% CI, −1.94 to 0.60) and G2 (ES −0.136; 95% CI, −0.12 to 1.62) FPMS scores were observed. Large ES for DJL loading rates (ES −1.89, 95% CI, 0.046 to 0.079) and YBT normalised anterior reach (ES 1.416, 95% CI, 66.30 to 73.29) were observed for G1 compared to G2 where trivial (ES 0.072, 95% CI, 0.067 to 0.095) and moderate effects (ES 1.104, 95% CI, 66.84 to 72.90), respectively, were observed. The magnitude of change for G1 was consistently greater for all DJL and YBT measures. Furthermore, SLST performance for G1 improved for all CoP measures whereas G2 decreased. The measures used to assess neuromuscular function indicate 8 weeks DT had meaningful effects on neuromuscular control; however, the magnitude of effects was greater for G1 than G2. As SLST, YBT and DJL indicated greater effects and are all proposed to predict injury, they could be a suitable surrogate marker for assessing the effects of DT. These findings also suggest that a lower dose of DT is sufficient provided training is individualised.
D2.P06. The effect of error in centre of pressure and knee joint centre location on knee adduction moment: a sensitivity analysis PATRICK CARDEN*, MICHAEL NUNNS & SHARON DIXON University of Exeter Corresponding author: [email protected] Large knee adduction moments (KAM) observed during human locomotion have been associated with increased risk of lower limb pathology in both sporting populations (Stefanyshyn et al., 2006, American Journal of Sports Medicine, 34, 1844–1851) and older adults (Baliunas et al.,
097, 2002, 10, 573–579). Frontal plane location of both the centre of pressure (CoP) and the knee joint centre of rotation (Knee CoR), when combined with the magnitude of ground reaction force (GRF), are the main determinants of the magnitude of KAM. Both kinematic data and CoP are susceptible to sources of error. While the typical error of both frontal plane joint angles and CoP has been established, the effect of error on joint kinetics during locomotion should be determined. The aim of the current investigation was therefore to quantify the sensitivity of KAM to error in frontal plane CoP and knee joint centre of rotation. Data for one female participant (age: 60 years, stature: 1.61 m, body mass: 57.3 kg) were selected for analysis from a larger participant group from a study with institutional ethical approval. The participant was asked to run at 3.3 m · s−1 ± 5% while three-dimensional movement of the right leg was synchronously recorded at 200 Hz (Codamotion) with ground reaction force data (AMTI), which was sampled at 1000 Hz. Marker trajectory and GRF data were filtered at 10 Hz. KAM was calculated within the Coda software using inverse dynamics. A systematic error was applied to mediolateral CoP and Knee CoR locations in 1 mm increments, synonymous with typical error values highlighted in previous studies (1–6 mm) prior to calculating joint moments. The KAM values with altered CoP and Knee CoR were compared to the KAM without additional error to determine the sensitivity of KAM to errors in CoP and Knee CoR location; this was determined by calculating route mean square error (RMSE). The findings of the study indicate that for every 1 mm of systematic error applied to mediolateral CoP location KAM RMSE was 0.02 (N · m) · kg−1. This was the same for variations applied to mediolateral Knee CoR, also with RMSE 0.02 (N · m) · kg−1 per 1 mm. This approach to modelling error in joint moment data highlights the importance for accurate CoP and Knee CoR data. For the data collection set-up and analysis procedures described, the level of confidence in KAM has been determined, permitting confident comparison of moment values between participants and between running conditions.
D2.P07. Centre of pressure excursion in footballers’ support limb when maximal instep shooting ANDREW MITCHELL* & KYLRN BROOKS-LYNCH
Day 2. Posters – biomechanics and motor behaviour
Downloaded by [Laurentian University] at 09:44 16 March 2016
University of Bedfordshire *Corresponding author: [email protected] Ball kicking techniques in football place the nonkicking support limb at increased risk of injury such as lateral ankle sprain. Epidemiology literature suggests that the risk of injury increases in the final third of each half as a result of fatigue (Hawkins et al., 2001, British Journal of Sports Medicine, 35, 43–47), that 39% of lateral ankle sprains occur in a noncontact mechanism and lateral ankle sprains account for 11% of injuries sustained in football (Woods et al., 2003, British Journal of Sports Medicine, 37, 233–238). The purpose of this study was to examine centre of pressure excursion (CPE) in the support limb, whilst shooting into three separate parts of the goal, in a non-fatigued condition and a globalised football specific fatigue condition. With institutional ethical approval, 15 right-foot dominant, male semiprofessional football players volunteered to participate in the study (age 22.4 years ± 2.8, height 178.87 m ± 0.67, mass 77 kg ± 11.3) (mean ± SD). Participants were required to kick a football into the left, centre and right side of the goal three times in a randomised order. Missed shots were excluded from the study and participants continued to shoot until nine successful shots were completed. Approach speed was controlled using light gates (Brower, Speedtrap II 3265a, Cranlea). Centre of pressure excursion in the anterior, posterior, medial, lateral, anteroposterior and mediolateral directions in the support limb were examined during the shooting trials in both conditions using a 0.5 m RS Scan Foot Scan Plate (RS Scan Lab Ltd). A significant increase in lateral CPE was observed with fatigue, specifically when shooting into the right target in comparison to the left (P = 0.009) and centre targets (P = 0.038). Significantly lower lateral CPE was observed when shooting into the centre target in the non-fatigued condition, when compared to shooting into the left (P = 0.016) or right targets (P = 0.003). Significantly higher mediolateral CPE was observed when shooting at the right (P = 0.005) and centre targets (P = 0.028) in the football-specific fatigued condition when compared to the non-fatigued condition. The results suggest that football players may be at a greater risk of injury such as lateral ankle sprain when shooting the ball in a fatigued condition. Targeted prehabilitation, such as single-leg proprioceptive exercises and strengthening of muscles controlling mediolateral CPE at the sub-talar and hip joints may serve to reduce this risk of injury. In addition, CPE in the support limb is influenced by the direction of the shot on goal and further research is required to examine potential performance benefits here.
s83
D2.P08. The reliability of inertial sensing technology for analysis of spinal kinematics during fast bowling in cricket BILLY SENINGTON1*, RAYMOND Y. LEE2 & JONATHAN M. WILLIAMS1 1
Bournemouth University; 2London University *Corresponding author: [email protected]
South
Bank
The analysis of fast bowling biomechanics has received much attention in the literature. However, the pathomechanics relating to injury are poorly understood. This understanding is critical if interventions to reduce injury risk are to be successful. Due to technological constraints the majority of research has been confined to the laboratory, increasing costs and restricting portability. Thus, application of such techniques to the wider fast bowling community is limited. Inertial sensors may be able to address limitations in current methods used for the motion analysis of fast bowling. Therefore, this study aims to investigate the reliability of inertial sensors for analysis of spinal kinematics during fast bowling in cricket. With institutional ethics approval, three professional fast bowlers were instrumented with three wireless inertial sensors (THETAmetrix, LSM303DLH) attached to the skin over the S1, L1 and T1 spinous processes. Sensors recorded absolute orientation and accelerations (±8 g) with data collected at 100 Hz. All data were transferred to MATLAB (Ed. R2012a) where peak sacral acceleration at back and front-foot impact was identified and used to denote the delivery stride. All data were filtered using a fourth-order, low-pass Butterworth filter with a cut-off frequency of 5 Hz. Spinal orientation at back and front-foot impact was determined and lumbar, thoracic and thoracolumbar kinematics were calculated from rotation matrices for the delivery stride. Absolute agreements of kinematic variables were calculated using two-way mixed model intra-class correlation coefficients (ICCs) with standard error of measurement (SEM) and minimal detectable change (MDC) also calculated. ICCs for lumbar flexion, thoracic lateral flexion and extension and thoracolumbar rotation demonstrated high reliability with ICCs between 0.83 and 0.96. All other measures displayed acceptable reliability with ICCs between 0.63 and 0.75. SEM for shoulder counterrotation and all lumbar kinematics was placed between 2.66° and 4.82°, demonstrating relatively low measurement error for
s84
Day 2. Posters – Biomechanics and Motor Behaviour
Downloaded by [Laurentian University] at 09:44 16 March 2016
such ballistic movements. MDC values for all other measurements ranged between 6.63° and 8.57°. Low MDC values were calculated for all measures, ranging from 4.52° to 8.11°. The above results demonstrate that inertial sensors may be suitable for measurement of three-dimensional spinal kinematics during fast bowling. SEM values highlight low measurement error, demonstrating high reliability. Low
MDC values verify that inertial sensors may be valuable to coaches in detecting or implementing changes in bowling technique. Consequently, inertial sensors may provide a more cost-effective and portable solution to current camera-based motion analysis systems, allowing coaches to give real-time feedback to players outside of a laboratory environment.
ISSN: 0264-0414 (Print) 1466-447X (Online) Journal homepage: http://www.tandfonline.com/loi/rjsp20
Day 2. Posters – Biomechanics and Motor Behaviour To cite this article: (2015) Day 2. Posters – Biomechanics and Motor Behaviour, Journal of Sports Sciences, 33:sup1, s81-s84, DOI: 10.1080/02640414.2015.1110332 To link to this article: http://dx.doi.org/10.1080/02640414.2015.1110332
Published online: 25 Nov 2015.
Submit your article to this journal
Article views: 94
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=rjsp20 Download by: [Laurentian University]
Date: 16 March 2016, At: 09:44
Journal of Sports Sciences, 2015 Vol. 33, Supplement 1, s81–s84, http://dx.doi.org/10.1080/02640414.2015.1110332
Day 2. Posters – Biomechanics and Motor Behaviour
D2.P04. Sex differences in maximum and explosive voluntary torque of the knee extensors and plantar flexors FEARGHAL BEHAN1,2*, MATTHEW PAIN1 & JONATHAN FOLLANDa,b Loughborough University; 2ARUK Centre for Sport, Exercise and Osteoarthritis *Corresponding author: [email protected]
Downloaded by [Laurentian University] at 09:44 16 March 2016
1
Explosive muscular force production is considered important for sport performance and injury prevention (Tillin and Folland, 2013, European Journal of Applied Physiology, 114, 365–374). Females have greater incidence of anterior cruciate knee ligament injuries than males and sex discrepancies in explosive force may be a contributory factor that requires further investigation. The aim of this study was to investigate sex differences in maximum voluntary torque (MVT) and explosive voluntary torque (EVT) in the knee extensors (KE) and plantar flexors (PF). Following ethical approval, neuromuscular performance of 21 untrained males (mean ± SD; age: 25.1 ± 4.9 years, height: 1.81 ± 0.09 m, mass: 81.4 ± 10.0 kg) and 20 untrained females (22.4 ± 3.1 years, 1.67 ± 0.06 m, 65.3 ± 9.2 kg) was assessed during maximal and explosive isometric knee extension and plantar flexion contractions. MVT was measured during maximum voluntary contractions and EVT at 25, 50, 75, 100, 150 and 200 ms from force onset during explosive contractions. A two-way repeated measures ANOVA and student’s independent t-tests with a Bonferroni correction were undertaken. Males were significantly stronger in KE (302 ± 43 N · m vs. 160 ± 31 N · m, P < 0.01) and PF (282 ± 56 N · m vs. 181 ± 36 N · m, P < 0.01) than females and displayed significantly greater EVT at all time-points in KE (P < 0.01) and from 50 to 200 ms in PF (P < 0.05). Males also had significantly greater MVT and EVT at all time-points in KE (MVT P < 0.01, EVT P < 0.05) and at 25 and 100–200 ms in PF (MVT P < 0.01, EVT P < 0.05) when force was normalised to body mass. However, when EVT was normalised to MVT there was no significant difference between the sexes (P = 0.372). Pooled data showed significant correlations between KE and PF MVT (absolute: r = 0.832, P < 0.01) and © 2015 Taylor & Francis
EVT from 50 to 200 ms (absolute: r = 0.488–0.763, P < 0.01; relative to MVT: r = 0.353–0.764, P < 0.05). Greater male MVT appears to explain their superior explosive force production in KE and PF in agreement with previous KE research (Hannah et al., 2012, Experimental Physiology, 97, 618–629). Additionally, KE and PF MVT and EVT appear moderately–strongly correlated. Future injury prevention programmes should emphasise increasing female absolute MVT as both genders appear to possess a similar ability to express their available force-generating capacity in an explosive manner.
D2.P05. The dose-response effects of dissociation training on measures of neuromuscular control during performance screening in male youth footballers ROBERT M. BURGE1*, GARY DAVENPORT2, STEPHEN TAYLOR2, JONATHAN D. HUGHES1 & MARK DE STE CROIX1 1
University of Gloucestershire; 2Bristol City Football Club *Corresponding author: [email protected] @RMBurge Movement screens purportedly identify compensatory kinematics that predispose athletes to injury (Kiesel, Plisky, and Butler, 2011,Scandinavian Journal of Medicine and Science in Sports, 21, 287–292). The efficacy of assessing select competencies and prescribing remedial training based on screen outcomes however remains equivocal. The Foundation Performance Matrix Screen© (FPMS) supposedly profiles injury risk, subsequently directing its independent motor control Dissociation Training (DT) (Mottram and Comerford, 2008, Physical Therapy in Sport, 9, 40–51). However, there appears to be no research evidencing that DT can improve FPMS score or reduce injury. The dose-response to DT therefore remains to be established. With institutional ethics approval, elite U15/ 16 and U17/18 male academy footballers comprised Group 1 (n = 6) (G1) and Group 2 (n = 8) (G2),
Downloaded by [Laurentian University] at 09:44 16 March 2016
s82
Day 2. Posters – Biomechanics and Motor Behaviour
respectively. G1 performed DT 1x week while G2 performed DT 3x week over 8 weeks. Centre of pressure (CoP) total, anterior-posterior (X) and medial-lateral (Y) displacements (cm), sway velocity (cm · s−1) and ellipse area (cm2) were recorded from participants’ non-dominant leg during a single leg stance test (SLST) and Y balance test™ (YBT). Force platform time to stabilisation (TTS), peak vertical ground reaction force (PVGRF) and loading rates were recorded from a 20-cm bilateral drop jump landing (DJL). The FPMS and YBT were scored according to respective guidelines. All tests were performed barefoot. Cohen’s d effect size (ES) was calculated from differences in means. Small ES for G1 (ES −0.180; 95% CI, −1.94 to 0.60) and G2 (ES −0.136; 95% CI, −0.12 to 1.62) FPMS scores were observed. Large ES for DJL loading rates (ES −1.89, 95% CI, 0.046 to 0.079) and YBT normalised anterior reach (ES 1.416, 95% CI, 66.30 to 73.29) were observed for G1 compared to G2 where trivial (ES 0.072, 95% CI, 0.067 to 0.095) and moderate effects (ES 1.104, 95% CI, 66.84 to 72.90), respectively, were observed. The magnitude of change for G1 was consistently greater for all DJL and YBT measures. Furthermore, SLST performance for G1 improved for all CoP measures whereas G2 decreased. The measures used to assess neuromuscular function indicate 8 weeks DT had meaningful effects on neuromuscular control; however, the magnitude of effects was greater for G1 than G2. As SLST, YBT and DJL indicated greater effects and are all proposed to predict injury, they could be a suitable surrogate marker for assessing the effects of DT. These findings also suggest that a lower dose of DT is sufficient provided training is individualised.
D2.P06. The effect of error in centre of pressure and knee joint centre location on knee adduction moment: a sensitivity analysis PATRICK CARDEN*, MICHAEL NUNNS & SHARON DIXON University of Exeter Corresponding author: [email protected] Large knee adduction moments (KAM) observed during human locomotion have been associated with increased risk of lower limb pathology in both sporting populations (Stefanyshyn et al., 2006, American Journal of Sports Medicine, 34, 1844–1851) and older adults (Baliunas et al.,
097, 2002, 10, 573–579). Frontal plane location of both the centre of pressure (CoP) and the knee joint centre of rotation (Knee CoR), when combined with the magnitude of ground reaction force (GRF), are the main determinants of the magnitude of KAM. Both kinematic data and CoP are susceptible to sources of error. While the typical error of both frontal plane joint angles and CoP has been established, the effect of error on joint kinetics during locomotion should be determined. The aim of the current investigation was therefore to quantify the sensitivity of KAM to error in frontal plane CoP and knee joint centre of rotation. Data for one female participant (age: 60 years, stature: 1.61 m, body mass: 57.3 kg) were selected for analysis from a larger participant group from a study with institutional ethical approval. The participant was asked to run at 3.3 m · s−1 ± 5% while three-dimensional movement of the right leg was synchronously recorded at 200 Hz (Codamotion) with ground reaction force data (AMTI), which was sampled at 1000 Hz. Marker trajectory and GRF data were filtered at 10 Hz. KAM was calculated within the Coda software using inverse dynamics. A systematic error was applied to mediolateral CoP and Knee CoR locations in 1 mm increments, synonymous with typical error values highlighted in previous studies (1–6 mm) prior to calculating joint moments. The KAM values with altered CoP and Knee CoR were compared to the KAM without additional error to determine the sensitivity of KAM to errors in CoP and Knee CoR location; this was determined by calculating route mean square error (RMSE). The findings of the study indicate that for every 1 mm of systematic error applied to mediolateral CoP location KAM RMSE was 0.02 (N · m) · kg−1. This was the same for variations applied to mediolateral Knee CoR, also with RMSE 0.02 (N · m) · kg−1 per 1 mm. This approach to modelling error in joint moment data highlights the importance for accurate CoP and Knee CoR data. For the data collection set-up and analysis procedures described, the level of confidence in KAM has been determined, permitting confident comparison of moment values between participants and between running conditions.
D2.P07. Centre of pressure excursion in footballers’ support limb when maximal instep shooting ANDREW MITCHELL* & KYLRN BROOKS-LYNCH
Day 2. Posters – biomechanics and motor behaviour
Downloaded by [Laurentian University] at 09:44 16 March 2016
University of Bedfordshire *Corresponding author: [email protected] Ball kicking techniques in football place the nonkicking support limb at increased risk of injury such as lateral ankle sprain. Epidemiology literature suggests that the risk of injury increases in the final third of each half as a result of fatigue (Hawkins et al., 2001, British Journal of Sports Medicine, 35, 43–47), that 39% of lateral ankle sprains occur in a noncontact mechanism and lateral ankle sprains account for 11% of injuries sustained in football (Woods et al., 2003, British Journal of Sports Medicine, 37, 233–238). The purpose of this study was to examine centre of pressure excursion (CPE) in the support limb, whilst shooting into three separate parts of the goal, in a non-fatigued condition and a globalised football specific fatigue condition. With institutional ethical approval, 15 right-foot dominant, male semiprofessional football players volunteered to participate in the study (age 22.4 years ± 2.8, height 178.87 m ± 0.67, mass 77 kg ± 11.3) (mean ± SD). Participants were required to kick a football into the left, centre and right side of the goal three times in a randomised order. Missed shots were excluded from the study and participants continued to shoot until nine successful shots were completed. Approach speed was controlled using light gates (Brower, Speedtrap II 3265a, Cranlea). Centre of pressure excursion in the anterior, posterior, medial, lateral, anteroposterior and mediolateral directions in the support limb were examined during the shooting trials in both conditions using a 0.5 m RS Scan Foot Scan Plate (RS Scan Lab Ltd). A significant increase in lateral CPE was observed with fatigue, specifically when shooting into the right target in comparison to the left (P = 0.009) and centre targets (P = 0.038). Significantly lower lateral CPE was observed when shooting into the centre target in the non-fatigued condition, when compared to shooting into the left (P = 0.016) or right targets (P = 0.003). Significantly higher mediolateral CPE was observed when shooting at the right (P = 0.005) and centre targets (P = 0.028) in the football-specific fatigued condition when compared to the non-fatigued condition. The results suggest that football players may be at a greater risk of injury such as lateral ankle sprain when shooting the ball in a fatigued condition. Targeted prehabilitation, such as single-leg proprioceptive exercises and strengthening of muscles controlling mediolateral CPE at the sub-talar and hip joints may serve to reduce this risk of injury. In addition, CPE in the support limb is influenced by the direction of the shot on goal and further research is required to examine potential performance benefits here.
s83
D2.P08. The reliability of inertial sensing technology for analysis of spinal kinematics during fast bowling in cricket BILLY SENINGTON1*, RAYMOND Y. LEE2 & JONATHAN M. WILLIAMS1 1
Bournemouth University; 2London University *Corresponding author: [email protected]
South
Bank
The analysis of fast bowling biomechanics has received much attention in the literature. However, the pathomechanics relating to injury are poorly understood. This understanding is critical if interventions to reduce injury risk are to be successful. Due to technological constraints the majority of research has been confined to the laboratory, increasing costs and restricting portability. Thus, application of such techniques to the wider fast bowling community is limited. Inertial sensors may be able to address limitations in current methods used for the motion analysis of fast bowling. Therefore, this study aims to investigate the reliability of inertial sensors for analysis of spinal kinematics during fast bowling in cricket. With institutional ethics approval, three professional fast bowlers were instrumented with three wireless inertial sensors (THETAmetrix, LSM303DLH) attached to the skin over the S1, L1 and T1 spinous processes. Sensors recorded absolute orientation and accelerations (±8 g) with data collected at 100 Hz. All data were transferred to MATLAB (Ed. R2012a) where peak sacral acceleration at back and front-foot impact was identified and used to denote the delivery stride. All data were filtered using a fourth-order, low-pass Butterworth filter with a cut-off frequency of 5 Hz. Spinal orientation at back and front-foot impact was determined and lumbar, thoracic and thoracolumbar kinematics were calculated from rotation matrices for the delivery stride. Absolute agreements of kinematic variables were calculated using two-way mixed model intra-class correlation coefficients (ICCs) with standard error of measurement (SEM) and minimal detectable change (MDC) also calculated. ICCs for lumbar flexion, thoracic lateral flexion and extension and thoracolumbar rotation demonstrated high reliability with ICCs between 0.83 and 0.96. All other measures displayed acceptable reliability with ICCs between 0.63 and 0.75. SEM for shoulder counterrotation and all lumbar kinematics was placed between 2.66° and 4.82°, demonstrating relatively low measurement error for
s84
Day 2. Posters – Biomechanics and Motor Behaviour
Downloaded by [Laurentian University] at 09:44 16 March 2016
such ballistic movements. MDC values for all other measurements ranged between 6.63° and 8.57°. Low MDC values were calculated for all measures, ranging from 4.52° to 8.11°. The above results demonstrate that inertial sensors may be suitable for measurement of three-dimensional spinal kinematics during fast bowling. SEM values highlight low measurement error, demonstrating high reliability. Low
MDC values verify that inertial sensors may be valuable to coaches in detecting or implementing changes in bowling technique. Consequently, inertial sensors may provide a more cost-effective and portable solution to current camera-based motion analysis systems, allowing coaches to give real-time feedback to players outside of a laboratory environment.
