Comparison of Countermovement Jump and Squat Jump Performance Between 627 State and Non-State Representative Junior Australian Football Players.

ABSTRACT: Edwards, T, Weakley, J, Woods, CT, Breed, R, Benson, AC, Suchomel, TJ, and Banyard, HG. Comparison of countermovement jump and squat jump performance between 627 state and non-state representative junior Australian football players. J Strength Cond Res 37(3): 641-645, 2023-This cross-sectional study investigated differences in lower-body power of state and nonstate representative junior Australian football (AF) players through countermovement jump (CMJ) and squat jump (SJ) performance. A total of 627 players performed the CMJ and SJ at the end of the preseason phase over a 2-week period, with each player grouped according to their age (under 18 [U18] or under 16 [U16]), and highest competition level played (state representation and nonstate representation). One-way multivariate analysis of variance (MANOVA), follow up ANOVA's, and Cohen's d effect sizes were used to identify significant main effects and between-group differences. Statistical significance was set at α < 0.05. Significant small-to-moderate effect size differences were observed between competition level, with state U18 and U16 players recording greater CMJ and SJ height, and peak power (PP), compared with their nonstate representative peers, respectively. Similarly, significant small-to-moderate effect size differences existed between age groups, with nonstate U18 players recording greater CMJ and SJ height and PP than nonstate U16 counterparts. However, state U18 and state U16 only differed in CMJ PP. No differences were found between competition level or age groups for the difference between CMJ and SJ jump height (CMJSJ diff ). Together, these findings suggest that state and nonstate representative junior AFs may have a similar ability to use the stretch-shortening cycle, despite state representative players jumping higher in the CMJ and SJ.

Poor Reporting of Exercise Interventions for Hamstring Strain Injury Rehabilitation: A Scoping Review of Reporting Quality and Content in Contemporary Applied Research.

OBJECTIVE: To review the quality of reporting and identify the content of exercise interventions prescribed for hamstring strain injury (HSI) rehabilitation in the scientific literature from 2010 to 2020. DESIGN: Scoping review. LITERATURE SEARCH: We searched the bibliometric databases Web of Science, CINAHL, SPORTDiscus, Scopus, Cochrane Library, MEDLINE, and Embase. STUDY SELECTION CRITERIA: Original research articles (randomized controlled trials and cohort studies) published from 2010 to 2020 that described an exercise rehabilitation intervention for participants with acute HSIs were included. Injuries must have been confirmed within 7 days of occurrence via clinical assessment and/or diagnostic imaging. DATA SYNTHESIS: The quality of reporting, in terms of completeness of exercise intervention description, was evaluated using the Consensus on Exercise Reporting Template (CERT), and the content of interventions was categorized into exercise types. RESULTS: Fourteen studies were included; exercise intervention quality of reporting was moderate in 3 studies and low in 11 studies. Using the 19-item CERT, an average of 8.8 items (range, 4-14) were reported across all studies. Two studies reported sufficient exercise content and progression information to allow replication. Exercises categorized as hamstring flexibility, hamstring strength, running related, and non-hamstring specific were prescribed in 13, 11, 10, and 10 studies, respectively. Half of the included studies incorporated all 4 exercise types in their exercise interventions. CONCLUSION: There is a wide variety of exercise interventions applied in published research that has addressed HSI rehabilitation. Researchers must improve reporting quality to support other professionals in replicating exercise interventions and help practitioners to effectively implement research in practice. J Orthop Sports Phys Ther 2022;52(3):130-141. Epub 21 Sep 2021. doi:10.2519/jospt.2022.10641.

Factors Affecting Set Shot Goal-kicking Performance in the Australian Football League.

Set shot goal-kicking is recognized as an important skill in Australian Football (AF), accounting for over half of all goals kicked in the Australian Football League (AFL). However, as knowledge surrounding its performance is limited, this study described the frequency, types, and outcomes of set shots in the AFL and investigated the impact of task, personal, and environmental constraints on goal-kicking performance. We analyzed video footage of set shots from all 198 matches of the 2012 season, collecting data for kick distance, kick angle, player position, player experience (i.e., general and specific), kick outcome, and weather status. We found an average of 23.0 (standard deviation [ SD] = 4.5) set shots/match, with a mean accuracy of 55.0% ( SD = 0.7%). Kicking accuracy decreased with incremental increases in kick distance, with accuracy ranging from 97% (0-15 m) to 36% (≥50 m). Key forwards were more accurate kickers than other players. There was no significant effect of player experience. The number of set shots taken decreased by 13% in wet weather conditions. The primary determinant of elite set shot goal-kicking performance was the interaction of kick distance and angle (task difficulty). This research adds to an understanding of how personal, environmental, and match constraints influence this closed skill performance in AF match play.

Tackle and impact detection in elite Australian football using wearable microsensor technology.

The effectiveness of a wearable microsensor device (MinimaxX(TM) S4, Catapult Innovations, Melbourne, VIC, Australia) to automatically detect tackles and impact events in elite Australian football (AF) was assessed during four matches. Video observation was used as the criterion measure. A total of 352 tackles were observed, with 78% correctly detected as tackles by the manufacturer's software. Tackles against (i.e. tackled by an opponent) were more accurately detected than tackles made (90% v 66%). Of the 77 tackles that were not detected at all, the majority (74%) were categorised as low-intensity. In contrast, a total of 1510 "tackle" events were detected, with only 18% of these verified as tackles. A further 57% were from contested ball situations involving player contact. The remaining 25% were in general play where no contact was evident; these were significantly lower in peak Player Load™ than those involving player contact (P < 0.01). The tackle detection algorithm, developed primarily for rugby, was not suitable for tackle detection in AF. The underlying sensor data may have the potential to detect a range of events within contact sports such as AF, yet to do so is a complex task and requires sophisticated sport and event-specific algorithms.

Quantification of tackling demands in professional Australian football using integrated wearable athlete tracking technology.

OBJECTIVES: To describe and quantify the frequency, velocity and acceleration at impact during tackling in Australian football using a combination of video and athlete tracking technology. DESIGN: Quasi-experimental. METHODS: Data was collected from twenty professional Australian Football League players during four in-season matches. All tackles made by the player and those against the player were video-coded and time stamped at the point of contact and then subjectively categorised into low, medium and high intensity impact groups. Peak GPS and acceleration data were identified at the point of contact. Two-way analysis of variance was used to assess differences (p<0.05) between tackle type (made and against) and tackle intensity. RESULTS: A total of 173 tackles made and 179 tackles against were recorded. Significant differences were found between all tackle intensity groups. Peak velocity was significantly greater in high (19.5±6.1 k mh(-1)) compared to medium (13.4±5.8 k mh(-1)) and low intensity (11.3±5.0 k mh(-1)) tackles. Peak Player Load, a modified vector magnitude of tri-axial acceleration, was significantly greater in high (7.5±1.7 a.u.) compared to medium (4.9±1.5 a.u.) and low intensity (4.0±1.3 a.u.) tackles. CONCLUSIONS: High intensity tackles, although less frequent, are significantly greater in speed of movement immediately prior to contact and in the resultant impact acceleration compared to tackles of lower intensity. Differences in accelerometer data between tackles observed to be progressively greater in intensity suggest a level of ecological validity and provide preliminary support for the use of accelerometers to assess impact forces in contact invasion sports.

The effect of a resistance training programme on the grab, track and swing starts in swimming.

The aim of this study was to establish the effectiveness of a resistance training programme, designed to improve vertical jumping ability, on the grab, swing and rear-weighted track starts in swimming. Twenty-three female non-competitive swimmers participated (age 19.9 +/- 2.4 years; mean +/- s). The diving techniques were practised weekly for 8 weeks. The participants were randomly assigned to a control group (n = 11) or a resistance-training group (n = 12), which trained three times a week for 9 weeks. The tests before and after the training programme involved performing each dive technique and six dry-land tests: two countermovement jumps (with and without arms), two isokinetic squats (bar speeds of 0.44 and 0.70 rad x s(-1)) and two overhead throws (with andwithout back extension). A repeated-measures multivariate analysis of variance was used to show that resistance training improved performance in the dry-land tests (P < 0.0001). No significant improvements due to training were found for any temporal, kinematic or kinetic variables within the grab or swing starts. Significant improvements (P < 0.05) were found for the track start for take-off velocity, take-off angle and horizontal impulse. The results suggest that the improved skill of vertical jumping was not transferred directly to the start, particularly in the grab technique. Non-significant trends towards improvement were observed within all starts for vertical force components, suggesting the need to practise the dives to retrain the changed neuromuscular properties.