DOES TECHNIQUE CHANGE AFFECT MUSCULAR SUPPORT AT THE KNEE IN SIDESTEP CUTTING?

Technique modification can reduce knee loads during sidestepping but its effect on muscular support has yet to be identified. Electromyography data was collected from ten muscles during sidestepping under planned and unplanned conditions, prior to and following training. Flexion/Extension and Medial/Lateral co-contraction ratios and total activation were calculated for pre-contact and weight acceptance phases. The only observed change due to training was unplanned tasks becoming more laterally dominated and planned tasks more medially. While significant these changes are nonfunctional as the ratios still represent high levels of co-contraction. Technique modification training should lower anterior cruciate ligament loads as it results in reduced knee moments but similar levels of muscular support, thus lowering the risk of injury

THE RELATIONSHIP BETWEEN NECK STRENGTH AND HEAD ACCELERATIONS IN A RUGBY TACKLE

The purpose of this study was to investigate the relationship between neck strength and head accelerations during a rugby tackle. Ten elite rugby players had their neck strength assessed and head accelerations tracked using a three dimensional motion analysis system during a rugby tackle. Higher levels of strength were related to lower head accelerations. Significant relationships were found between coronal plane accelerations and flexion and extension strength. The findings support those in the literature suggesting that increasing neck strength is a potential target to reduce sport concussions

NEUROMUSCULAR ADAPTATIONS TO BALANCE AND TECHNIQUE TRAINING DURING SIDESTEPPING: IMPLICATIONS FOR ACL INJURY RISK

This study investigated the influence of balance and technique training (BTT) on external knee joint loading and the activation of muscles crossing the knee during anticipated (AnSS) and unanticipated (UnSS) sidestepping. Twenty-eight males participated in a 28 week training intervention implemented adjunct to their regular season training. Twelve completed BTT and 16 completed a ‘sham’ training (ST) intervention. Knee moments and the activation of 8 muscles crossing the knee were collected during AnSS and UnSS prior to and following training. BTT did not influence the activation of the muscles crossing the knee during AnSS or UnSS. Increases in muscle activation were not proportional to increases in valgus knee moments during UnSS in both groups. Unanticipated sport tasks should be identified as distinct factors associated with ACL injury risk

Changes in muscle activation following balance and technique training and a season of Australian football

Objectives: Determine if balance and technique training implemented adjunct to 1001 male Australian football players' training influenced the activation/strength of the muscles crossing the knee during pre-planned and unplanned sidestepping. Design: Randomized Control Trial. Methods: Each Australian football player participated in either 28 weeks of balance and technique training or 'sham' training. Twenty-eight Australian football players (balance and technique training, n = 12; 'sham' training, n = 16) completed biomechanical testing pre-to-post training. Peak knee moments and directed co-contraction ratios in three degrees of freedom, as well as total muscle activation were calculated during pre-planned and unplanned sidestepping. Results: No significant differences in muscle activation/strength were observed between the 'sham' training and balance and technique training groups. Following a season of Australian football, knee extensor (p = 0.023) and semimembranosus (p = 0.006) muscle activation increased during both pre-planned sidestepping and unplanned sidestepping. Following a season of Australian football, total muscle activation was 30% lower and peak valgus knee moments 80% greater (p = 0.022) during unplanned sidestepping when compared with pre-planned sidestepping. Conclusions: When implemented in a community level training environment, balance and technique training was not effective in changing the activation of the muscles crossing the knee during sidestepping. Following a season of Australian football, players are better able to support both frontal and sagittal plane knee moments. When compared to pre-planned sidestepping, Australian football players may be at increased risk of anterior cruciate ligament injury during unplanned sidestepping in the latter half of an Australian football season

Comparing the effectiveness of a short-term vertical jump vs. weightlifting program on athletic power development

Efficient training of neuromuscular power and the translation of this power to sport-specific tasks is a key objective in the preparation of athletes involved in team-based sports. The purpose of the current study was to compare changes in center of mass (COM) neuromuscular power and performance of sport-specific tasks following short-term (6-week) training adopting either Olympic Style Weightlifting (WL) exercises or vertical jump (VJ) exercises. Twenty six recreationally active males (18-30 years; height: 178.7±8.3 cm; mass: 78.6±12.2 kg) were randomly allocated to either a WL or VJ training group and performance during the countermovement jump (CMJ), squat jump (SJ), depth jump (DJ), 20m sprint and the 5-0-5 agility test assessed pre- and post-training. Despite the WL group demonstrating larger increases in peak power output during the CMJ (WL group: 10% increase, d=0.701; VJ group: 5.78% increase, d=0.328) and SJ (WL group: 12.73% increase, d=0.854; VJ group: 7.27% increase, d=0.382), no significant between-group differences were observed in any outcome measure studied. There was a significant main effect of time observed for the three vertical jumps (CMJ, SJ, DJ), 0-5m and 0-20m sprint times, and the 5-0-5 agility test time, which were all shown to improve following the training (all main effects of time p<0.01). Irrespective of the training approach adopted by coaches or athletes, addition of either WL or VJ training for development of power can improve performance in tasks associated with team-based sports, even in athletes with limited pre-season training periods

Visual-perceptual training with acquisition of the observed motor pattern contributes to greater improvement of visual anticipation

This experiment investigated the contribution of visual and additive motor experience to improvement of visual anticipation. Club cricket batters were randomized into (a) a visual-perceptual group that received temporal occlusion training (n = 13), (b) a visuomotor group that received temporal occlusion training coupled with motor pattern practice of the observed bowler's action (n = 13), and (c) a no-training control group (n = 13). They completed a fast bowler video-based temporal occlusion prepost anticipation test, as well as a transfer temporal occlusion test that included different fast and slow bowlers. Results indicated visual-perceptual and visuomotor groups equally improved pick up of advance cues across prepost tests. Additive motor pattern practice for the visuomotor group facilitated superior anticipation through earlier pick up of advance information across the transfer tests. No improvement was found for the control group. The findings indicate that visual and combined motor experience facilitates learning, but additive motor experience facilitates superior transfer. Findings have implications for theoretical and applied knowledge to develop anticipation skill. © 2019 American Psychological Association

The King-Devick test is a valid and reliable tool for assessing sport-related concussion in Australian football: A prospective cohort study

Objectives: Sport-related concussion (SRC) research has focused on impaired oculomotor function. The King-Devick (K-D) test measures oculomotor performance and is reported to identify suboptimal brain function. The use of the K-D test in Australian football (AF), a sport involving body contact and tackling, has not been documented. Therefore, the objective of this study was to determine the test-retest reliability and diagnostic accuracy of the K-D test on a sub-elite AF team.Design: Prospective cohort studyMethods: In total, 22 male players (19.6 + 2.3 years) were tested and re-tested on the K-D test. Those suspected of having a SRC secondary to a significant head impact were tested. Randomly selected additional players without SRC were assessed for comparison.Results: There were observable learning effects between the first and second baseline testing (48 vs. 46 s). The ICC for the first and second baseline tests was 0.91. Post-match test times were longer than the baseline times for players with SRC (n = 7) (-1.9 s; z = -5.08; p p Conclusions: This study supports the use of the K-D test due to its test-retest reliability, high sensitivity and specificity, and fast and simple use that is ideal for sports medicine professionals to make quick judgement on management and playability

In situ use of the King-Devick eye tracking test and changes seen with sport-related concussion: saccadic and blinks counts

Objectives: Sport-related concussion (SRC) can result in impaired oculomotor function. Oculomotor performance, measured utilizing the King-Devick/Eye Tracking test (K-D/ET), is reported to be able to identify sub-optimal brain function. The objectives of the study were to determine the diagnostic accuracy of the K-D/ET in identifying SRC occurring from game participation and to perform a comparative analysis on saccade and blink counts for each K-D card individually and total counts between baseline and post-concussion.Methods: Nineteen male Australian Football players were assessed on the K-D/ET test. Those suspected of having SRC secondary to a head impact were also tested.Results: Participants recorded a slower time on the third (20.2 ± 4.6 s) screen when compared with the first (p = 0.0424) and second (p = 0.0150) screens. The number of blinks was higher on the third (2.9 ± 2.9) when compared with the second (p = 0.0057) screen. There was decrease of the K-D/ET total times between pre- and post-game (p = 0.1769). Participants who sustained a head impact recorded slower mean total K-D time (p = 0.7322), fewer mean total saccades (p = 0.0112), and more mean blinks (p = 0.8678) compared with their baseline scores. The assessment of blinks was the most sensitive measure for potential SRC (0.67). The K-D/ET duration was the most specific measure for potential SRC (0.88). An increase in the number of blinks had a fair specificity of 0.69. Conclusion: The rapid number-naming component of the K-D test is an assessment tool which quantifies impairment to oculomotor function and has been validated as a diagnostic tool for SRC. The clinical usefulness of the eye tracking component of the K-D/ET test is that it may be an effective method to assess concussions with the eye tracking component serving as a measure of progression and return to play. However, more research is required at the adult and youth level

Youth Australian footballers experience similar impact forces to the head as junior- and senior-league players: A prospective study of kinematic measurements

The aims of this study were to investigate the frequency, magnitude, and distribution of head impacts sustained by youth AF players over a season of games and report subjective descriptions on the mechanism-of-injury and sign and symptoms experienced. A prospective observational cohort study with participants (n = 19) (age range 13-14 yr., mean ± SD 13.9 ± 0.3 yr.) wearing a wireless impact measuring device behind their right ear over the mastoid process prior to game participation. Participants completed an individual post-game logbook providing feedback responses on recalling having a direct hit to their head with another player or the surface. Players experienced a mean (SD) of 5 (±4) impacts per-player per-game. The peak linear rotation (PLA) median, (95th percentiles) were 15.2g (45.8g). The median (95th percentile) peak rotational acceleration (PRA) were 183,117 deg/s2 (594,272 deg/s2). Median (95th percentile) Head Impact Telemetry Severity profile were 15.1 (46.1) and Risk Weighted Exposure Combined Probability were 0.0012 (0.7062). Twelve participants reported sustaining a head impact. Players reporting a head impact had a faster mean impact duration (t(25) = 2.4; p = 0.0025) and had a lower median PLA(g) (F(23,2) = 845.5; p = 0.0012) than those who did not report a head impact. These results show similar measurements to the older junior- (aged 17-19) and senior-league (20+) players. Furthermore, players who reported sustaining a direct or indirect impact during games had similar measurements to those who did not, thus highlighting the difficulty of concussion recognition, at least with youth. Future research may need to establish the relationship between concussion-like symptoms in the absence of an impact and in relation to concussion evaluation assessments such as the King-Devick and SCAT5