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Speed influences on decision making in elite Australian football umpires
Abstracts / Journal of Science and Medicine in Sport 20S (2017) e106–e128
270 Speed influences on decision making in elite Australian football umpires N. Macdonald, A. Kittel, M. Spittle, N. Elsworthy ∗ College of Sport and Exercise Science, Victoria University, Australia Introduction: Above real time training (ARTT) has previously been used as a training methodology in military and sport scenarios to improve decision making skill (Lorains et al., 2013). These decisions, however, are typically followed by the execution of a skill. This differs to that of Australian Football (AF) umpires who do not need to execute a skill, and are only required to make decisions based on applying the laws of the game. Therefore, the aim of this research was to assess video-based decision making skill of elite AF umpires at different video speeds. Methods: 30 video clips were randomly presented to 16 elite AF umpires at speeds below real time (0.75) or above real time (1.25, 1.5, 1.75 and 2.0) of normal (1.0) game day footage featuring a potential free kick situation. Umpires were required to make a decision based on each clip, either awarding a free kick, or “play on” if there was no infringement identified. Following each clip, umpires rated how game-like each video felt on a scale from 1 to 7, with a rating of 4 being considered most ‘game-like’, 1 being “too slow” and 7 being “too fast”. A within subject analysis of variance was performed to investigate the effects of video speed on accuracy and game-likeness. Effect sizes (ES) were calculated using the partial eta squared statistics (2p ). Results: There was a significant main effect for video speed on decision making accuracy (P < 0.001; 2p : 0.339). Accuracy was significantly higher for the 0.75, 1.0, 1.25 and 1.5 speeds (88–95% correct), compared to the 1.75 (69 ± 15%) and 2.0 speeds (76 ± 15%) (all P < 0.05). There was a significant effect for ratings of video speed for game-likeness (P < 0.001; 2p : 0.964), with 1.0 (3.9 ± 0.3), 1.25 (4.7 ± 0.5) and 1.5 (5.5 ± 0.4) speeds identified as the most gamelike. There were significant differences across all speeds as found in the pairwise comparisons for game-likeness. Discussion: These results outline significant variations in decision making accuracy and ratings of game-likeness within elite AF umpires. It is likely that important perceptual information may not be correctly interpreted during the 1.75 and 2.0 speeds resulting in poorer ability to determine the correct decision. Umpires also perceived these clips to be “too fast” and therefore not very game like. These findings suggest that for AF umpires, 1.25 and 1.5 video speeds may be appropriate for the implementation of ARTT. http://dx.doi.org/10.1016/j.jsams.2017.01.200 271 Neuromuscular changes post sports concussion in elite football players J. Hides 1,∗ , M. Franettovich Smith 1 , D. Mendis 1 , N. Smith 1 , A. Cooper 1 , J. Treleaven 2 , N. Low Choy 3 1 Centre for Musculoskeletal Research, Australian Catholic University, Australia 2 Division of Physiotherapy, The University of Queensland, Australia 3 School of Physiotherapy, Australian Catholic University, Australia
Introduction: Concussion is a significant injury in collision sports and manifests itself via a multitude of symptoms including
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dizziness, altered proprioception, balance, and spinal control. Furthermore, sustaining a concussion significantly increases the risk of sustaining another concussion, and is attributed to higher musculoskeletal injury in the ensuing 12 months. Reasons for this are unclear and further investigations into the effects of concussion may improve physiotherapy management of concussed patients. Methods: A prospective cohort study was conducted with baseline assessments of 53 subjects from an elite rugby league and rugby union team at the start of a playing season. Follow-up measures were conducted within 72 h of a player who sustained a concussion. Measures included a self-reported questionnaire, balance assessment (stability evaluation test (SET)), vestibular system function (vestibular oculo-motor reflex and benign paroxysmal positional vertigo), ultrasound of trunk muscles (size and voluntary contraction ability) and cervical spine proprioception (joint position error). Results: A total of 19 concussions were sustained by 15 players during the playing season. Of the 15 players with a concussion, 5 (33%) had a history of concussion in the preceding 12 months. At baseline (start of season), a moderate (effect size 0.6–0.7) reduction in sway on one balance condition (tandem on foam) and a large decrease (effect size 0.8) in multifidus muscle size (L5 vertebral level) were associated with players who went on to sustain a season concussion. From pre- to post-concussion, moderate to large reductions (effect size 0.6–0.9) in sway velocity for the single and bilateral foam and composite SET measures were observed. Large increases (effect size 0.8) were observed post-concussion for the resting size of the (R) L4 multifidus and bilaterally at L5. Post-concussion moderate (effect size 0.5–0.6) increases in the (L) multifidus contraction size and thickness of the internal oblique were observed. There were also large, insignificant individual variations within the vestibular and cervical proprioception systems. Discussion: Although the study had a reasonable baseline sample size, statistical power was compromised because in-season concussions occurred in 27% of the sample and only 8 (12.5%) had sensory tests administered pre-concussion. These findings following concussion suggest an altered strategy of balance and trunk muscle control, which may provide part of the explanation for the previously documented increase in injury rate post-concussion. This is the first study of its kind to assess a number of different measures in the post-concussed player that are potentially amenable with physiotherapy treatment. http://dx.doi.org/10.1016/j.jsams.2017.01.201 272 Influence of drill type and unit fitting on accelerometer derived loads in rugby league training C. Cummins 1,∗ , B. McLean 2 , G. Conlan 2 , A. Coutts 3 1
Faculty of Health Sciences, University of Sydney, Lidcombe, NSW, Australia 2 School of Exercise Science, Australian Catholic University, Melbourne, Australia 3 Sport & Exercise Discipline Group, University of Technology Sydney (UTS), Sydney, Australia Background: The high sampling rate (100 Hz) of tri-axial accelerometers within microtechnology devices, means poorly fitted devices may increase incidental unit movement, resulting in increased variability and decreased sensitivity of accelerometerderived loads. Whilst accelerometer loads have demonstrated moderate-high test-retest reliability (CV = 5.9%) during treadmill running, there is no information examining accelerometer-derived
270 Speed influences on decision making in elite Australian football umpires N. Macdonald, A. Kittel, M. Spittle, N. Elsworthy ∗ College of Sport and Exercise Science, Victoria University, Australia Introduction: Above real time training (ARTT) has previously been used as a training methodology in military and sport scenarios to improve decision making skill (Lorains et al., 2013). These decisions, however, are typically followed by the execution of a skill. This differs to that of Australian Football (AF) umpires who do not need to execute a skill, and are only required to make decisions based on applying the laws of the game. Therefore, the aim of this research was to assess video-based decision making skill of elite AF umpires at different video speeds. Methods: 30 video clips were randomly presented to 16 elite AF umpires at speeds below real time (0.75) or above real time (1.25, 1.5, 1.75 and 2.0) of normal (1.0) game day footage featuring a potential free kick situation. Umpires were required to make a decision based on each clip, either awarding a free kick, or “play on” if there was no infringement identified. Following each clip, umpires rated how game-like each video felt on a scale from 1 to 7, with a rating of 4 being considered most ‘game-like’, 1 being “too slow” and 7 being “too fast”. A within subject analysis of variance was performed to investigate the effects of video speed on accuracy and game-likeness. Effect sizes (ES) were calculated using the partial eta squared statistics (2p ). Results: There was a significant main effect for video speed on decision making accuracy (P < 0.001; 2p : 0.339). Accuracy was significantly higher for the 0.75, 1.0, 1.25 and 1.5 speeds (88–95% correct), compared to the 1.75 (69 ± 15%) and 2.0 speeds (76 ± 15%) (all P < 0.05). There was a significant effect for ratings of video speed for game-likeness (P < 0.001; 2p : 0.964), with 1.0 (3.9 ± 0.3), 1.25 (4.7 ± 0.5) and 1.5 (5.5 ± 0.4) speeds identified as the most gamelike. There were significant differences across all speeds as found in the pairwise comparisons for game-likeness. Discussion: These results outline significant variations in decision making accuracy and ratings of game-likeness within elite AF umpires. It is likely that important perceptual information may not be correctly interpreted during the 1.75 and 2.0 speeds resulting in poorer ability to determine the correct decision. Umpires also perceived these clips to be “too fast” and therefore not very game like. These findings suggest that for AF umpires, 1.25 and 1.5 video speeds may be appropriate for the implementation of ARTT. http://dx.doi.org/10.1016/j.jsams.2017.01.200 271 Neuromuscular changes post sports concussion in elite football players J. Hides 1,∗ , M. Franettovich Smith 1 , D. Mendis 1 , N. Smith 1 , A. Cooper 1 , J. Treleaven 2 , N. Low Choy 3 1 Centre for Musculoskeletal Research, Australian Catholic University, Australia 2 Division of Physiotherapy, The University of Queensland, Australia 3 School of Physiotherapy, Australian Catholic University, Australia
Introduction: Concussion is a significant injury in collision sports and manifests itself via a multitude of symptoms including
e117
dizziness, altered proprioception, balance, and spinal control. Furthermore, sustaining a concussion significantly increases the risk of sustaining another concussion, and is attributed to higher musculoskeletal injury in the ensuing 12 months. Reasons for this are unclear and further investigations into the effects of concussion may improve physiotherapy management of concussed patients. Methods: A prospective cohort study was conducted with baseline assessments of 53 subjects from an elite rugby league and rugby union team at the start of a playing season. Follow-up measures were conducted within 72 h of a player who sustained a concussion. Measures included a self-reported questionnaire, balance assessment (stability evaluation test (SET)), vestibular system function (vestibular oculo-motor reflex and benign paroxysmal positional vertigo), ultrasound of trunk muscles (size and voluntary contraction ability) and cervical spine proprioception (joint position error). Results: A total of 19 concussions were sustained by 15 players during the playing season. Of the 15 players with a concussion, 5 (33%) had a history of concussion in the preceding 12 months. At baseline (start of season), a moderate (effect size 0.6–0.7) reduction in sway on one balance condition (tandem on foam) and a large decrease (effect size 0.8) in multifidus muscle size (L5 vertebral level) were associated with players who went on to sustain a season concussion. From pre- to post-concussion, moderate to large reductions (effect size 0.6–0.9) in sway velocity for the single and bilateral foam and composite SET measures were observed. Large increases (effect size 0.8) were observed post-concussion for the resting size of the (R) L4 multifidus and bilaterally at L5. Post-concussion moderate (effect size 0.5–0.6) increases in the (L) multifidus contraction size and thickness of the internal oblique were observed. There were also large, insignificant individual variations within the vestibular and cervical proprioception systems. Discussion: Although the study had a reasonable baseline sample size, statistical power was compromised because in-season concussions occurred in 27% of the sample and only 8 (12.5%) had sensory tests administered pre-concussion. These findings following concussion suggest an altered strategy of balance and trunk muscle control, which may provide part of the explanation for the previously documented increase in injury rate post-concussion. This is the first study of its kind to assess a number of different measures in the post-concussed player that are potentially amenable with physiotherapy treatment. http://dx.doi.org/10.1016/j.jsams.2017.01.201 272 Influence of drill type and unit fitting on accelerometer derived loads in rugby league training C. Cummins 1,∗ , B. McLean 2 , G. Conlan 2 , A. Coutts 3 1
Faculty of Health Sciences, University of Sydney, Lidcombe, NSW, Australia 2 School of Exercise Science, Australian Catholic University, Melbourne, Australia 3 Sport & Exercise Discipline Group, University of Technology Sydney (UTS), Sydney, Australia Background: The high sampling rate (100 Hz) of tri-axial accelerometers within microtechnology devices, means poorly fitted devices may increase incidental unit movement, resulting in increased variability and decreased sensitivity of accelerometerderived loads. Whilst accelerometer loads have demonstrated moderate-high test-retest reliability (CV = 5.9%) during treadmill running, there is no information examining accelerometer-derived