Standardisation of acceleration zones in professional field sport athletes

Running acceleration data provides important information about the physical demands placed on field sport athletes. However, the absence of clearly defined acceleration zones has contributed to the minimal examination of this variable. This study aimed to develop a standardised set of acceleration zones and determine any differences in accelerations between elite and sub-elite Australian footballers. Thirty-nine professional male Australian footballers performed a 30 m sprint from a standing start. Timing lights were placed at 0, 10, 20 and 30 m to calculate accelerations over 0-10, 10-20 and 20-30 m splits. The accelerations over these splits were 3.27 m·s-2, 1.81 m·s-2 and 0.33 m·s-2. The differences between the elite and sub-elite groups for time, velocity and acceleration over the splits were examined using independent t-tests and effect sizes. Acceleration zones were determined by using maximal acceleration to establish the subsequent acceleration zones. In this case 20%, 45% and 85% of maximum acceleration were used to develop low (0.65-1.46 m·s-2), moderate (1.47-2.77 m·s-2) and high (>2.78 m·s-2) zones. No differences between the elite and sub-elite athletes for each acceleration category were found. The development of standardised acceleration zones will assist with the assessment and understanding of accelerations in field sport athletes. This has the potential to improve the implementation of training programs and recovery sessions. Further, these accelerations zones are seemingly applicable for both elite and sub-elite field sport athletes

Simplifying the complexity of assessing physical performance in professional Australian football

© 2020 Informa UK Limited, trading as Taylor & Francis Group. Purpose: To provide a simplified, novel method for analysing the physical demands in an Australian Football context by reducing the dimensionality of commonly reported physical characteristics obtained from match play. This may facilitate their practical use and interpretability. Methods: A retrospective longitudinal design was utilised with individual players’ physical outputs, measured via global navigation satellite system devices, collected during official Australian Football League matches over three seasons. A principal component analysis was used to reduce a large number of correlated physical characteristics related to the analysis of physical match demands into a smaller set of uncorrelated components. Results: Forty-six variables were reduced to five principal components whilst maintaining 56% of the variance in the original dataset. The principal component analysis derived five individual-based principal components pertaining to low-moderate movement volume, high speed running volume, accelerations, change of direction and impacts. Conclusions: Utilising factor loadings (eigenvectors) derived from a principal component analysis, this study is the first to provide a simplified, novel method for analysing the physical demands in an Australian Football context with the derived metrics revealing useful information for coaches and practitioners. This may consequently guide training implementation, player performance ratings and player selection. Further, these new values may facilitate the monitoring of physical player loads

Relationship between stiffness and lower body soft-tissue injury in professional Australian Rules footballers

Leg stiffness is a modifiable mechanical property that may be related to soft tissue injury risk. The purpose of this study was to examine mean leg stiffness and bilateral differences in leg stiffness across an entire professional Australian Football League (AFL) season, and determine whether this parameter was related to the incidence of lower body soft tissue injury. The stiffness of the left and right legs of 39 professional AFL players (age 24.4 +/- 4.4 years, body mass 87.4 +/- 8.1 kg, stature 1.87 +/- 0.07 m) was measured using a unilateral hopping test at least once per month throughout the season. Injury data were obtained directly from the head medical officer at the football club. Mean leg stiffness and bilateral differences in leg stiffness were compared between the injured and non-injured players. There was no difference between the season mean leg stiffness values for the injured (219.3 +/- 16.1 N . m(-1) . kg(-1)) and non-injured (217.4 +/- 14.9 N . m(-1) . kg(-1); P = 0.721) groups. The injured group (7.5 +/- 3.0%) recorded a significantly higher season mean bilateral difference in leg stiffness than the non-injured group (5.5 +/- 1.3%; P = 0.05). A relatively high bilateral difference in leg stiffness appears to be related to the incidence of soft tissue injury in Australian football players. This information is of particular importance to medical and conditioning staff across a variety of sports