Lower-limb injury in elite Australian football: A narrative review of kinanthropometric and physical risk factors

Hamstring and knee injuries are associated with isometric hip and trunk muscle strength in elite Australian Rules and Rugby League players

OBJECTIVES

This study investigated relationships between isometric trunk and hip extensor strength, lumbar muscle morphology, and the risk of hamstring and knee ligament injuries in Australian Football League and National Rugby League players.

DESIGN

Prospective cohort study.

METHODS

Trunk and hip extensor strength, multifidus and quadratus lumborum cross-sectional area were measured during the 2020 pre-season. Logistic regressions and decision trees were employed to explore associations between maximum strength, strength endurance, multifidus and quadratus lumborum cross-sectional area, age, previous injuries, and hamstring and knee ligament injury risk.

RESULTS

Greater strength endurance [odds ratio = 0.42 (0.23-0.74), p = 0.004] and maximum strength [odds ratio = 0.55 (0.31-0.94), p = 0.039] reduced hamstring injury risk. Increased risk of knee ligament injuries was associated with larger multifidus [odds ratio = 1.66 (1.14-2.45), p = 0.008] and higher multifidus to quadratus lumborum ratio (odds ratio = 1.57 (1.13-2.23), p = 0.008]. Decision tree models indicated that low strength endurance (< 99 Nm) characterised hamstring strains, while high (≥ 1.33) multifidus to quadratus lumborum ratio mitigated risk. Knee ligament injuries were associated with larger (≥ 8.49 cm2) multifidus, greater (≥ 1.25) multifidus to quadratus lumborum ratio, and lower maximum strength (< 9.24 N/kg).

CONCLUSIONS

Players with lower trunk and hip extensor maximum strength and strength endurance had increased risk of hamstring injuries, while knee ligament injury risk was elevated with larger multifidus cross-sectional area, higher multifidus to quadratus lumborum ratio, and lower maximum trunk and hip extensor strength.

Preseason Body Composition Is Associated With In-season Player Availability in Elite Male Australian Footballers

ABSTRACT

McCaskie, CJ, Sim, M, Newton, RU, Heasman, J, Rogalski, B, and Hart, NH. Preseason body composition is associated with in-season player availability in elite male Australian footballers. J Strength Cond Res XX(X): 000-000, 2022-The purpose of this study was to examine whether end of preseason body composition characteristics was associated with in-season match availability and injury. Sixty (n = 60) elite Australian football players had body composition characteristics assessed using dual-energy X-ray absorptiometry across 3 seasons (2016, 2018, and 2021). Match availability and injury were recorded throughout each season. Pearson's correlations were calculated to assess the associations between body composition and in-season match availability and injury. Logistic regression models were used to assess the odds of missing games as a result of injury throughout a season. Regional lean soft tissue mass asymmetry and its relationship to injury and availability was explored. Statistical significance was set at p ≤ 0.05. Body composition characteristics expressed as relative values seemed to be more highly associated with in-season availability and injury than characteristics expressed as absolute values. Players with lower relative fat mass (FM) (<12.1% total body FM) were available for 89.7% of in-season matches compared with 80.7% for players with higher relative FM (>12.1% total body FM). Subsequently, players with higher relative FM had 3.3-3.5 times greater odds of missing one game to injury (odds ratio [OR] = 3.33; 95% confidence interval [CI] = 1.00-11.14; p ≤ 0.05) and missing 2 or more games to injury (OR = 3.50; 95% CI = 1.20-10.20; p ≤ 0.05) throughout a season compared with players with lower relative FM. Higher proportions of fat mass may accelerate the onset of fatigue and place players at a greater risk of injury. Reducing players' FM across the preseason phase should be a key aim for practitioners to reduce the odds of injury throughout the competitive season.

Pre-season body composition has minimal influence on in-season match availability, and match performance in female Australian Football League (AFLW) players

This study examined the relationship between pre-season body composition, in-season match performance, and match availability in female players competing in the Australian Football League Women's (AFLW) competition. With the outlawing of body composition assessments as part of pre-draft player evaluations in the AFLW, this study seeks to examine whether this is justified. Twenty-two (n = 22) players had body composition assessed with dual-energy x-ray absorptiometry at the beginning of the 2021 AFLW pre-season (whole-body and regional fat mass and lean soft-tissue mass [LSTM]). In-season match availability and match performance data (Coaches Score [CS], Champion Data Player Rank, average disposals, disposal and kicking efficiency) were collected throughout the 2021 competition. Pearson correlations were performed to assess if associations existed between body composition and in-season match performance and availability. A median split was performed to divide players into higher and lower performing groups for match performance variables. Two-sample independent t-tests were then used to assess differences between groups. No body composition characteristics could differentiate between in-season match availability groups (100% availability vs. <100% availability) or higher and lower performing groups for all match performance variables. Total leg LSTM asymmetry shared a moderate negative association with CS. Body composition may not be important for determining in-season match availability and performance in female AFLW players. Thus, the repercussions following the removal of pre-draft body composition assessments across the league may not be as significant as is currently perceived. Other physiological, biomechanical, or performance qualities are more variable and may mask the effect of body composition in these players. AFLW practitioners should prioritize the development of other important attributes, such as aerobic fitness, muscular strength and power, and technical skill.

Genetic Variants within NOGGIN, COL1A1, COL5A1, and IGF2 are Associated with Musculoskeletal Injuries in Elite Male Australian Football League Players: A Preliminary Study

INTRODUCTION

Australian Football is a dynamic team sport that requires many athletic traits to succeed. Due to this combination of traits, as well as technical skill and physicality, there are many types of injuries that could occur. Injuries are not only a hindrance to the individual player, but to the team as a whole. Many strength and conditioning personnel strive to minimise injuries to players to accomplish team success.

PURPOSE

To investigate whether selected polymorphisms have an association with injury occurrence in elite male Australian Football players.

METHODS

Using DNA obtained from 46 elite male players, we investigated the associations of injury-related polymorphisms across multiple genes (ACTN3, CCL2, COL1A1, COL5A1, COL12A1, EMILIN1, IGF2, NOGGIN, SMAD6) with injury incidence, severity, type (contact and non-contact), and tissue (muscle, bone, tendon, ligament) over 7 years in one Australian Football League team.

RESULTS

A significant association was observed between the rs1372857 variant in NOGGIN (p = 0.023) and the number of total muscle injuries, with carriers of the GG genotype having a higher estimated number of injuries, and moderate, or combined moderate and high severity rated total muscle injuries. The COL5A1 rs12722TT genotype also had a significant association (p = 0.028) with the number of total muscle injuries. The COL5A1 variant also had a significant association with contact bone injuries (p = 0.030), with a significant association being found with moderate rated injuries. The IGF2 rs3213221-CC variant was significantly associated with a higher estimated number of contact tendon injuries per game (p = 0.028), while a higher estimated number of total ligament (p = 0.019) and non-contact ligament (p = 0.002) injuries per game were significantly associated with carriage of the COL1A1 rs1800012-TT genotype.

CONCLUSIONS

Our preliminary study is the first to examine associations between genetic variants and injury in Australian Football. NOGGIN rs1372857-GG, COL5A1 rs12722-TT, IGF2 rs3213221-CC, and COL1A1 rs1800012-TT genotypes held various associations with muscle-, bone-, tendon- and ligament-related injuries of differing severities. To further increase our understanding of these, and other, genetic variant associations with injury, competition-wide AFL studies that use more players and a larger array of gene candidates is essential.

Characterising lower-body musculoskeletal morphology and whole-body composition of elite female and male Australian Football players

BACKGROUND

Physical demands and injury rates differ between elite female and male Australian Football (AF) players. To improve understanding of contributing physical factors to these differences, the purpose of this study was to investigate lower-body morphology and whole-body composition of elite footballers competing in the Australian Football League (AFL) and Australian Football League Women's (AFLW).

METHODS

Lower-body morphology and whole-body composition of 23 AFL players and 23 AFLW players were assessed using peripheral Quantitative Computed Tomography and Dual-energy X-ray Absorptiometry at the beginning of pre-season. Differences between cohorts, with sub-analyses of kicking vs. support limbs, and experienced vs. inexperienced player status were assessed using two-sample independent t-tests. Magnitude of differences were assessed using Cohen's d effect sizes.

RESULTS

AFL players had greater absolute (p < 0.001; ES = 3.28) and relative (p < 0.001; ES = 2.29) whole body lean soft-tissue mass, with less absolute (p = 0.004; ES = 0.91) and relative (p < 0.001; ES = 2.29) fat mass than AFLW players. For AFLW players, no significant differences existed between kicking and support limbs with few differences observed between experienced and inexperienced players.

CONCLUSIONS

Greater emphasis on physical development in AFLW players may be required to enable increases in muscle mass and skeletal robustness, to ensure they can tolerate the loads of elite competition.

Force, Power, and Morphology Asymmetries as Injury Risk Factors in Physically Active Men and Women

This study aimed to investigate whether asymmetry of force, power, and tissue morphology are lower limbs (LL) injury risk factors in physically active adults. Fifty-eight men aged 23.8 ± 1.2 years and forty-seven women aged 23.3 ± 1.0 years were examined. Physical activity level was measured by the International Physical Activity Questionnaire, and injury data were collected with the Injury History Questionnaire. The countermovement jump was performed to evaluate force and power. LL tissue composition was evaluated by a bioimpedance analyzer. The symmetry indices were calculated. A comparison between injured and non-injured subjects in both sexes was conducted to determine indices associated with injuries. The symmetry indices cut-off points were calculated to establish values indicating a significant injury risk increase, and logistic regression was performed. The relative peak force asymmetry above 4.049% was associated with increased injury risk in men. The LL skeletal muscle mass asymmetry above 3.584% was associated with a higher injury risk in women. Increased asymmetry in indicated indices by 1% was associated with 19.8% higher injury risk in men and 82.6% in women. Asymmetry proved to be an injury risk factor. However, a more suitable index for men is relative peak force asymmetry, whereas LL skeletal muscle mass asymmetry is more suitable for women.