Australian Football (AF) players require well-developed physical capacities to cope with the demands of competition. Recent match analysis research shows that at the professional level, AF players travel ∼11–13 km during matches at an average speed of 108–128 m·min−1 (10,26). This activity profile is very stochastic with players completing many intense accelerations and decelerations, which often include changes of direction (10,12). The technical demands require that many physically challenging skills are completed, including kicking, jumping, tackling, jostling, and colliding with opponents (15,25). Additionally, although the number of tackles in each match in elite AF is considerably less than other contact team sports, such as rugby union and rugby league (16), many of these (∼38%) are completed at high speeds (>14.4 km·h−1) (16), further demonstrating the intense nature of AF.
Because of these demands, a main objective when preparing AF players for higher level competition is to develop specific physique and associated physiological capacities. In particular, optimizing fat-free soft tissue mass (FFSTM) and maintaining lower levels of fat mass (FM) are often a priority with younger players. At present, however, there is a poor understanding of the relationships between physique, body composition, and physical performance across the various levels of competition. Specifically, a greater understanding of the differences in body composition and its relationship to muscular strength and power between the various levels of competition along the AF development pathway to the Australian Football League (AFL) is required.
There are several development pathways through which talented AF players may be recruited to play in the AFL. These include the national U18 competition and the state-based open-age leagues. Talented young players are typically recruited into the AFL from the national U18 competition, with the better players usually being invited to nominate for the national draft through which they can be recruited by one of the 18 AFL teams. Commonly, AFL clubs will recruit these young players with the longer term view of developing them over several years before they become regular first team players in the AFL. Less commonly, older, physically mature successful players (i.e., >20 years) are being recruited to the AFL from the major state-based open-age leagues. These players are typically referred to as mature age recruits. One advantage of recruiting these older players is that they tend to be physically more developed because of an increase in training experience and have well-developed physical capacities that allow them to be selected for first team matches in the AFL soon after being drafted (11).
Several recent studies have described the physical characteristics and match activity profiles of the players competing at the various levels of competition in the AF talent pathways. For example, differences in match activity profiles have been observed between elite senior, sub-elite senior (2,5,6), and elite junior AF players (7,28). In general, these studies have shown increased intensity with competitive level with more sprinting, accelerations, and higher speed ruining compared with the lower standard counterparts. Surprisingly, however, there have been few studies that have described the differences in body composition (17,18,27) and strength power characteristics (8,22,29) between the various levels of competition. These studies have shown that lower-body power measures may differentiate between “selected” and “nonselected” players onto elite senior AF teams (8,29), with AF players showing higher levels of lower-body power than sub-elite senior counterparts, despite no differences in body mass or maximal strength. These differences may be explained by increased FFSTM in higher level athletes.
Fat-free soft tissue mass tends to increase with age and training experience (3) and has been suggested to underpin many of the differences in physical qualities between the playing levels (23). Although FFSTM increases through maturation in younger athletes, strength training will also assist in the development of muscle mass, strength, and power (14). One study has described the differences in body composition between elite junior and elite senior AF players, with elite junior players displaying ∼6% lower body mass and FFSTM than elite senior AF players, although the elite junior players were not different to the first year elite senior AFL players who were of similar age (28). However, despite this previous study, there is limited information on the differences in body composition and their relationships to strength power and performance in AF players at the different stages of the AF development pathway. Therefore, the aim of this study was to compare the anthropometric characteristics in elite junior, sub-elite senior, and elite senior AF players. The second purpose was to examine the relationships of FFSTM with muscular strength and power at each playing level.
Experimental Approach to the Problem
This cross-sectional investigation compared upper-body strength and lower-body power with body composition between elite junior, sub-elite senior, and elite senior AF players. Upper-body strength was assessed by a 1 repetition maximum (1RM) bench press and bench pull. Lower-body power was assessed by countermovement jump (CMJ) and loaded squat jump (SJ20). In addition, body composition measures of FFSTM, FM, and bone mineral content (BMC) were assessed using a pencil beam dual-energy x-ray absorptiometry (DXA, Lunar DPX-IQ, Madison, WI, USA; GE, Lunar Corp, USA) on the same day as the strength and CMJ measures. All testing sessions were completed over 2 weeks during the mid-season break.
Forty-seven elite senior (age 22.8 ± 3.0 years, mass 86.8 ± 7.9 kg, stature 188 ± 7 cm), 22 sub-elite senior (age 21.5 ± 2.1 years, mass 83.7 ± 9.4 kg, stature 183 ± 7 cm), and 21 elite junior (age 18.0 ± 0.6 years, mass 78.5 ± 8.1 kg, stature 185 ± 9 cm) AF players were recruited for the study. The elite senior AF players were from the same professional AFL club (Carlton Football Club, Carlton, Victoria, Australia) and, for the purposes of this study, were subdivided into experienced and inexperienced elite senior players. Experienced elite senior players were classified as players who had been contracted to an AFL club ≥4 years, whereas the inexperienced elite senior players had been contracted to an AFL club <4 years. All the sub-elite senior players competed in the state-based competition (Northern Bullants, Victorian Football League, Victoria, Australia), and the elite junior players played in the same U18 team (Northern Knights, TAC Cup, Victoria, Australia). The methods for the study were approved by the university ethics committee and by the corresponding clubs involved. All participants provided written informed consent before commencing the study, including parental consent for all individuals under the age of 18 years.
The players from each team typically completed 1–2 resistance sessions, 2 skill-based sessions, and a competitive match each week. In addition, the experienced and inexperienced elite senior players performed supplementary training sessions, mainly consisting of aerobic cross-training (once per week) and 2–3 injury prevention sessions (i.e., jump and land, pilates, water mobility, and proprioceptive training).
Each player was assessed for anthropometric profile (regional [i.e., arms, trunk, and legs] and whole-body FFSTM, FM, and BMC) with a pencil beam DXA (Lunar DPX-IQ; GE, Lunar Corp) using standard analysis software (Software SmartScan Version 4.7e). To minimize scanning errors, procedures were standardized according to the recommendations of the Australian and New Zealand Bone and Mineral Society (1). The players were all placed with hands in a pronated flat position, fingers together within the scan range. The leg position was standardized via internally rotating at the hip joint and then secured with straps to reduce bone overlap in lower limbs. The players removed metal objects or jewelry from their body and wore the same minimal clothing (underwear) for each scan. To ensure hydration was optimal before each scan, they were instructed to follow a standardized fluid and food intake before scanning (i.e., a 45-g cereal with skim milk and 1.5 L of water). No player had any metallic implants in this investigation, which can influence BMC. The same technician analyzed all scans. Automatic analysis software of the DXA regions of interest was then confirmed by the technician after adjusting for accuracy.
The coefficients of variation (CVs) of repeated total whole-body DXA measurements in this laboratory were body mass (kg) = 0.34%, BMC (g) = 1.49%, FFSTM (g) = 0.48%, and FM (g) = 5.85%. Validity CV measures for BMC = 2.32%, FFSTM = 0.51%, and FM = 17.87%. Details of regional reliability and validity of the DXA measures in AF players of this laboratory were reported elsewhere (4).
Because of constraints imposed by the football club, a restricted battery of physical performance characteristics of lower-body power and upper-body strength were assessed. The CMJ and SJ20 tests were used to assess the power output of the lower body (13,22). Upper-body strength was assessed as this quality is important for tackling, fending-off opponents, and the execution of the skills involving the upper body (20). Lower-body power was assessed because this is an important quality related to accelerating, higher speed running, kicking, and jumping—which are fundamental skills for AF performance (20). All power tests were completed before any of the strength testing. Peak distance and peak velocity during a CMJ were used to assess lower-body power using a linear position transducer (PT5A; Fitness Technology, South Australia, Australia). Furthermore, a loaded (20 kg) SJ (SJ20) was used to evaluate neuromuscular performance of the lower body against an increased external load. We chose to use an absolute load with this testing battery (20 kg) for logistical reasons because it is more time consuming to perform relative load testing and this was part of the clubs' historical testing protocols. This is problematic when conducting testing with professional athletes during the competition period. Additionally, we also chose the loaded SJ (SJ20) as the ability to move an absolute mass regardless of the differences of body mass between players is important to consider, especially in contact sports that require direct competition with opponents (e.g., tackling and jostling with opponents). Each player was given time to familiarize themselves with practice jumps on a separate occasion. All players had refrained from exercise for a minimum of 2 days before testing. The results of each performance test were presented as absolute values and also relative to FFSTM.
To assess upper-body strength, a 1RM for bench press and a bench pull was performed (21). Program constraints did not allow for lower-body strength testing because of perceived risk of injury. All players followed a standardized warm-up period for 15 minutes and then commenced a series of lifts for each of the bench press and bench pull as warm-ups in preparation for the testing protocols. The following protocol was followed for each lift. Historical data were used to estimate 1RM values. Each exercise required 6 repetitions at 50% of 1RM, 4 repetitions at 60% of 1RM, 3 repetitions at 70% of 1RM, 2 repetitions at 80% of 1RM, followed by 1 repetition at 90% of 1RM. The player then attempted 1 repetition at 100% and if successful would increase loads by increments of 2.5 kg. The bench press was completed first until 1RM was determined, followed by the same procedure for the bench pull exercise. There was 4–6 minutes rest between each attempt and 10 minutes rest between upper-body exercises. For the bench press, participants used a self-selected handgrip and lowered the bar to a 90° angle at the elbow, which was determined and verbally cued by the strength coach. During the bench pull, the participants were instructed to have chest in contact with the bench at all times. Once lying on the bench, participants would use a slightly wider than shoulder width grip and pull the bar directly upward where a successful lift constituted the bar coming in contact with the underside of the bench. The test was terminated when the player failed twice to lift a particular weight.
The players were required to complete the CMJ and loaded SJ using a position transducer (PT5A; Fitness Technology) to assess jump height. The position transducer was interfaced with computer software (Ballistic Measurement System; Fitness Technology) that allowed direct measurement of displacement-time and velocity-time variables (13). Test-retest reliability for jump height for this test is r = 0.95 with a CV of 3.5% (22). Players were provided a marked black square where feet were placed as a starting point, and a successful jump meant that they landed within that square to ensure minimal error because of lateral movement. The athlete was also instructed to keep the bar intact with shoulders during the jump to avoid an inflated bar velocity and distance reading.
Both a CMJ, using a wooden bar held behind the neck, and an SJ20 were conducted on each testing occasion according to previously described methods (22). A 20-kg barbell, held across the shoulders, was used for the loaded SJ. Each SJ20 involved the subject flexing the knees to approximately 90° angle (self-selected by the athlete and confirmed by the strength coach), maintaining the position for 3 seconds, and then jumping on the command “go.” The CMJ was performed under the same conditions but involved flexion of the knee followed immediately by triple extension of the hip, knee, and ankle joints without a 3-second pause, which allowed for the stretch-shorten cycle. The loaded SJ was completed 5 minutes after the CMJ. If the athlete failed to complete the jump correctly, it was repeated after a brief recovery period (4–6 minutes).
All data are presented as mean ± SD unless otherwise stated. Before using parametric statistical test procedures, the assumptions of normality and sphericity were verified. A 1-way analysis of variance assessed differences between the playing levels (experienced elite senior, inexperienced elite senior, sub-elite senior, and elite junior) in these measures. A Bonferroni post hoc was used to locate group differences. Cohen's d effect sizes (d) were also calculated to examine the practical significance of the differences in strength. The effect sizes were classified as trivial, small, moderate, large, very large, or nearly perfect if they exceeded the values of 0.0, 0.2, 0.6, 1.2, 2.0, and 4.0, respectively (19). Relationships between upper-body strength, body composition, and CMJ/SJ performance were evaluated using Pearson's correlation coefficient (r). The magnitude of the correlations was also determined using the modified scale by Hopkins (19): r < 0.1, trivial; 0.1–0.3, small; 0.3–0.5, moderate; 0.5–0.7, large; 0.7–0.9, very large; >0.9, nearly perfect; and 1, perfect. Statistical significance for all analyses was defined by p ≤0.05.
The experienced elite senior and sub-elite senior players were older, heavier (all p ≤ 0.05, Table 1), and displayed greater FFSTM than the elite junior players (p ≤ 0.05, Table 2). Despite being heavier, there was no difference in the percentage of FFSTM among the groups. In addition, the experienced elite senior players had large (d = 0.77) and moderate (d = 0.47) differences in stature compared with the sub-elite senior and elite junior players, respectively. Both the experienced and inexperienced elite senior players had significantly greater total FFSTM than the elite junior players, with large differences for the experienced elite senior (d = 1.05) and inexperienced elite senior (d = 1.03) groups, respectively.
Analysis in Table 2 showed significantly greater FFSTM in both the elite senior playing groups compared with the elite junior players in the arms (experienced elite senior: d = 1.28, inexperienced elite senior: d = 1.17) and trunk (experienced elite senior: d = 1.10, inexperienced elite senior: d = 1.02, Table 2). Similarly, regional BMC was also greater in the experienced elite senior (arms: d = 1.29, trunk: d = 1.14, legs: d = 0.93) and inexperienced elite senior players (arms: d = 1.02, trunk: d = 1.01, legs: d = 0.66) compared with elite junior players. Trunk BMC (d = 0.60) was greater in the sub-elite senior group compared with the elite junior group. There were no differences between the playing levels in either whole-body or appendicular FFSTM when expressed as a proportion of body mass.
There were large to very large differences between elite senior (both experienced and inexperienced) and elite junior players for absolute upper-body strength (range, d = 1.35–1.57) and weighted SJ and CMJ peak velocities (range, d = 1.35–1.57, Table 1). When expressed relative to FFSTM, there were large to very large differences between the elite senior players and elite junior players for bench press (d = 0.84–0.94) and large differences for bench pull (d = 0.84–1.21) between the elite senior players and the sub-elite senior and elite junior players. There were large differences in the CMJ height expressed relative to FFSTM between the senior players at all levels and the elite junior players (d = 0.73–0.88) but no between-group differences for the SJ20 height expressed relative to FFSTM. Similarly, when the peak velocities achieved during the SJ20 and CMJ were expressed relative to FFSTM, there were very large differences between the experienced senior players and the sub-elite senior (d = 1.37) and elite youth (d = 1.53) players and very large differences between the elite youth players and the senior players at all levels for the SJ20 (d = 1.49–1.59).
Figure 1 shows that both whole-body and regional FFSTM measures were correlated with bench press (whole body: r = 0.43, arms: r = 0.64), bench pull (whole body: r = 0.58, arms: r = 0.73), and SJ performance measures (whole body: r = 0.33, legs: r = 0.55). There were also large to very large correlations between age and body mass (r = 0.85), FFSTM (r = 0.86), BMC (r = 0.86), bench press (r = 0.85), and bench pull (r = 0.85). There were moderate to large correlations between age and weighted and unweighted CMJ height (CMJ: r = −0.36, SJ20: r = −0.38) and peak velocity measures (CMJ: r = 0.69, SJ20: r = 0.65).
The primary aim of this study was to examine the anthropometric characteristics and parameters of muscular strength and explosive power performance in elite junior, sub-elite senior, inexperienced elite senior, and experienced elite senior AF players. In addition, we also examined the relationships between age, body composition, and physical performance measures. The main findings from this investigation were that elite senior professional AF players were significantly older, heavier, stronger, and had better CMJ performance than their elite junior AF counterparts. Although the proportional (percentage) FFSTM and FM were not different between all 3 groups, there were differences in absolute FFSTM, FM, and BMC, mostly between the elite senior and elite junior groups.
In agreement with recent studies (27), we observed differences in many anthropometric variables between the playing levels. Only one previous study (27) has examined the differences in anthropometric characteristics between elite senior and elite junior AF players. Similar to the present results, this previous study also demonstrated that the elite juniors had lower body mass and FFSTM than elite senior AF players. Moreover, although the absolute FFSTM was significantly higher with superior playing level, the relative proportions of FFSTM were not significantly different between levels (27), highlighting that AF players at these playing levels have a low level of FM.
In line with the differences in body composition between the playing levels in AF, several studies have also shown differences in strength and power between playing levels (8,29). For example, Caia et al. (8) reported differences between elite senior and sub-elite senior AF players in lower-body power assessed through SJ peak power and weighted CMJ despite no differences in body mass or maximal strength. The present results showed that both the experienced and inexperienced elite senior players had greater absolute and relative upper-body strength and unweighted CMJ performance than the sub-elite senior and elite junior players. The most likely explanations for the differences between the junior and senior playing levels in the present study are the effects of years of training—which can increase both FFSTM and also relative and absolute strength and power performance. Moreover, the very strong correlations between age and anthropometric and upper-body strength characteristics also highlight the benefits of consistent training for AF athletes in developing physical and strength/power characteristics. Indeed, both the experienced and inexperienced elite senior players in this study are employed full time to prepare for competition and hence are likely to spend more time training and would benefit from a higher level of nutrition and training support than the sub-elite senior and elite junior players. In contrast, the elite junior players were much younger and are more likely to have less resistance training experience and may even not have reached full skeletal or muscular development, which is supported by the lower FFSTM identified in this group in the present study. Collectively, these factors are likely to explain the differences in both absolute and relative physical performance measures in the present study and highlight the importance of increasing muscle mass to accommodate the large increases in the strength and power required at higher levels of play (8,29).
A new contribution of the current analysis is the specific differences in regional segments (e.g., arms, BMC, etc.). In the present study, we observed large to very large differences in FFSTM of arms (d = 1.28) and trunk (d = 1.10) between experienced elite senior and elite junior and moderate differences (d = 0.30–0.61) with inexperienced elite senior AF players. There were smaller nonsignificant differences (d = 0.75) in leg FFSTM between the levels, suggesting that higher level athletes focus more on developing upper-body size. These observations are supported by the large differences in upper-body strength measures between the groups in this study. Although speculative, the increased focus on upper-body strength may be developed to cope with increased speed, collisions, and physicality at the higher levels.
In general, high levels of weight-bearing physical activity are associated with an enhanced BMC (24). In support, we observed nonsignificant trends for increasing BMC at higher levels of competition and a very strong correlation between players' age and BMC (r = 0.86). Although not directly assessed in this study, the most likely explanation is the differences between training exposures at the various competition levels; however, the role of incomplete maturation in the elite junior group cannot be discounted. It was notable that the magnitude of difference between the experienced elite senior and elite junior players for the trunk (d = 1.14) and arm (d = 1.29) BMC was much larger compared with the leg BMC (d = 0.93). It is likely that the increased upper-body resistance training history in the experienced elite senior players explains the greater differences in these regions. Similar to studies that have observed increased BMC and bone mineral density in soccer players compared with age-matched control, the present findings may have implications for using football training in preventing the risk factors for developing osteoporosis with aging (9). Whether the increased BMC provides additional protection against fractures during match play is yet to be assessed; however, it is likely to be beneficial.
Although recent studies have shown differences in strength and power between levels (8,29), none have explored relationships with FFSTM in AF. The present results showed strong relationships between FFSTM (both whole body and appendicular) and physical performance with moderate to strong correlations with upper-body test results (bench press, r = 0.43–0.64; bench pull, r = 0.58–0.73) and CMJ performance (r = 0.33–0.55). Although these observations may be logical for experienced strength and conditioning coaches, these findings provide additional support for developing FFSTM in young players to prepare them for elite-level AF. Specific focus on prescribing appropriate periodized resistance training and nutritional strategies during the developmental years in talented young AF players may be crucial for the transition to higher level competitions. Specifically, increasing upper-body FFSTM along with absolute and relative strength and power characteristics may be an important focus for younger players.
There are some limitations with the design and implementation of the present study that must be acknowledged. First, the results in this study are only taken from single clubs competing in each of the different levels of competition. Accordingly, the results of this study may be affected by the training and player recruitment strategies of each of these clubs. To overcome this limitation, larger groups of players from a variety of clubs and playing positions should be examined. Alternatively, longitudinal studies following players developing from elite junior to elite senior professional players could be implemented. Additionally, the present study was conducted during the competition phase of training; it is possible that the relationships observed in the present study may differ at different stages of the season when the focus of training changes. Future studies could examine these seasonal changes in body composition and physical performance in AF players. Finally, the present findings are limited to a narrow battery of strength and power tests and the absence of direct measures of force and power. Future studies should adopt a more comprehensive range of strength and power tests for upper and lower body using external loads calculated as a proportion of individual maximum strength to provide a more thorough understanding of the relationships between body composition and strength and power characteristics in AF.
In summary, the main findings from this investigation were that elite senior professional AF players were significantly older, heavier, have greater absolute and relative strength, and possess better CMJ performance than their elite junior AF counterparts. The present results also demonstrated that whole-body and appendicular FFSTM are different between playing levels in AF. These differences are most likely reflective of differences in training and maturation status and partly explain the observed differences in strength and power between the playing levels.
It is logical that in collision sports, such as AF, where relative strength and power are important (8,22), training for developing professional athletes should be aimed at increasing FFSTM, strength, and power while maintaining very low FM. The present findings highlight that young or developing AF players should focus on developing FFSTM to best prepare for the AFL. However, from a practical perspective, it is important that physical development is not prioritized at the expense of a program that also delivers appropriate development in fundamental training skills and healthy eating habits, as these are likely to build the foundations of long-term training adaptations. Analysis of the AFL draft results from 2000 to 2007 showed that although 50% of first time draftees play at least one game in the year subsequent to selection, it is not until the third year after the draft that the majority (>50%) of players are regular senior players (10 or more games in a season) for their club. Coaches should also be aware that it can take >3 years to optimally develop the player's body composition (i.e., increase FFSTM and decrease FM) but perhaps not strength and power capacities after players have been recruited into a professional club. Recruiters should also be aware that although players from the sub-elite senior leagues typically have more FFSTM compared with elite junior players, they are not developed in their strength and power capacities and FFSTM levels to the extent of elite senior players and therefore may require specific training to optimize FFSTM and physical performance. Future studies on the longitudinal changes in body composition and physical performance in developing AF players are still required to understand the physical performance development projections of young players in the first few years of entering a professional club.
The Carlton Football Club supported this research.
1. ANZBMS. Clinical Densitometry Course Notes. Sydney, NSW, Australia: Australian and New Zealand Bone Mineral Society Society, 2013.
2. Aughey RJ. Widening margin in activity profile between elite and sub-elite Australian football: A case study. J Sci Med Sport 16: 382–386, 2013.
3. Baxter-Jones AD, Eisenmann JC, Mirwald RL, Faulkner RA, Bailey DA. The influence of physical activity on lean mass accrual during adolescence: A longitudinal analysis. J Appl Physiol 105: 734–741, 2008.
4. Bilsborough JC, Greenway K, Livingstone S, Cordy J, Coutts AJ. The accuracy and precision of DXA
for assessing body composition
in trained team sport athletes. J Sports Sci 32: 1821–1828, 2014.
5. Boyd LJ, Ball K, Aughey RJ. Quantifying external load in Australian football matches and training using accelerometers. Int J Sports Physiol Perf 8: 44–51, 2013.
6. Brewer C, Dawson B, Heasman J, Stewart G, Cormack S. Movement pattern comparisons in elite (AFL) and sub-elite (WAFL) Australian football games using GPS. J Sci Med Sport 13: 618–623, 2010.
7. Burgess D, Naughton G, Norton K. Quantifying the gap between under 18 and senior AFL football: 2003–2009. Int J Sports Physiol Perf 7: 53–58, 2012.
8. Caia J, Doyle TL, Benson AC. A cross-sectional lower-body power profile of elite and sub-elite Australian football players. J Strength Cond Res 27: 2836–2841, 2013.
9. Calbet JA, Dorado C, Diaz-Herrera P, Rodriguez-Rodriguez LP. High femoral bone mineral content and density in male football (soccer) players. Med Sci Sports Exerc 33: 1682–1687, 2001.
10. Coutts AJ, Kempton T, Bilsborough JC, Sullivan CJ, Cordy J, Rampinini E. Metabolic power demands of professional Australian Football match-play. J Sci Med Sport, 2014. in press.
11. Coutts AJ, Kempton T, Vaeyens R. Relative age effects in Australian Football League draftees. J Sports Sci 32: 623–628, 2013.
12. Dawson B, Hopkinson R, Appleby B, Stewart G, Roberts C. Player movement patterns and game activities in the Australian Football League. J Sci Med Sport 7: 278–291, 2004.
13. Dugan EL, Doyle TL, Humphries B, Hasson CJ, Newton RU. Determining the optimal load for jump squats: A review of methods and calculations. J Strength Cond Res 18: 668–674, 2004.
14. Folland JP, Williams AG. The adaptations to strength training: Morphological and neurological contributions to increased strength. Sports Med 37: 145–168, 2007.
15. Gastin PB, Bennett G, Cook J. Biological maturity influences running performance
in junior Australian football. J Sci Med Sport 16: 140–145, 2013.
16. Gastin PB, McLean O, Spittle M, Breed RV. Quantification of tackling demands in professional Australian football using integrated wearable athlete tracking technology. J Sci Med Sport 16: 589–593, 2013.
17. Hart NH, Nimphius S, Cochrane JL, Newton RU. Leg mass characteristics of accurate and inaccurate kickers—An Australian football perspective. J Sports Sci 31: 1647–1655, 2013.
18. Hart NH, Nimphius S, Spiteri T, Newton RU. Leg strength and lean mass symmetry influences kicking performance
in Australian Football. J Sports Sci Med 13: 157–165, 2014.
19. Hopkins WG. A scale of magnitudes for effect statistics. Sportscience 9: 17–20, 2000.
20. Hrysomallis C, Buttifant D. Influence of training years on upper-body strength and power changes during the competitive season for professional Australian rules football players. J Sci Med Sport 15: 374–378, 2012.
21. Liow DK, Hopkins WG. Velocity specificity of weight training for kayak sprint performance
. Med Sci Sports Exerc 35: 1232–1237, 2003.
22. McGuigan MR, Cormack S, Newton RU. Long-term power performance
of elite Australian rules football players. J Strength Cond Res 23: 26–32, 2009.
23. Milanese C, Piscitelli F, Lampis C, Zancanaro C. Anthropometry and body composition
of female handball players according to competitive level or the playing position. J Sports Sci 29: 1301–1309, 2011.
24. Pirnay F, Bodeux M, Crielaard JM, Franchimont P. Bone mineral content and physical activity. Int J Sports Med 8: 331–335, 1987.
25. Sullivan C, Bilsborough JC, Cianciosi M, Hocking J, Cordy JT, Coutts AJ. Factors affecting match performance
in professional Australian Football. Int J Sports Physiol Perf 9: 561–566, 2014.
26. Sullivan C, Bilsborough JC, Cianciosi M, Hocking J, Cordy J, Coutts AJ. Match score affects activity profile and skill performance
in professional Australian Football players. J Sci Med Sport 17: 326–331, 2014.
27. Veale JP, Pearce AJ, Buttifant D, Carlson JS. Anthropometric profiling of elite junior and senior Australian football players. Int J Sports Physiol Perf 5: 509–520, 2010.
28. Veale JP, Pearce AJ, Koehn S, Carlson JS. Performance
and anthropometric characteristics of prospective elite junior Australian footballers: A case study in one junior team. J Sci Med Sport 11: 227–230, 2008.
29. Young WB, Newton RU, Doyle TL, Chapman D, Cormack S, Stewart G, Dawson B. Physiological and anthropometric characteristics of starters and non-starters and playing positions in elite Australian rules football: A case study. J Sci Med Sport 8: 333–345, 2005.
Keywords:Copyright © 2015 by the National Strength & Conditioning Association.
performance; DXA; body composition