Figures Journal of Strength and Conditioning Research Publish Ahead of Print DOI: 10.1519/JSC.0000000000001861
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Title: The seasonal variations in anthropometric and performance characteristics of elite inter
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county Gaelic football players.
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Authors: Richard A. Kelly1, 2, Kieran Collins1
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Affiliations:
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1. Research Institute for Sport and Exercise Sciences, Liverpool John Moore’s University, Henry
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Cotton Campus, 15–21 Webster Street, Liverpool, L3 2ET
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2. Gaelic Sports Research Centre, Department of Science, Institute of Technology Tallaght, Tallaght,
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Dublin, Ireland.
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Corresponding Author: Richard Kelly
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Research Institute for Sport and Exercise Sciences,
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Liverpool John Moore’s University,
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Henry Cotton Campus,
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15-21 Webster Street, Liverpool, L3 2ET
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Category of manuscript: Original article
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Email:
[email protected] Tel: (+44) 7763 085494
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Copyright ª 2017 National Strength and Conditioning Association
24 ABSTRACT
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There is limited research assessing the anthropometric and performance variations in elite
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Gaelic football. The aim of the current study was to assess the anthropometric and performance
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characteristics of an elite inter-county squad within a season. Following ethical approval and informed
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consent 26 participants were assessed at the start of pre-season (November), following early in-season
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(January) and mid-season (March). Measurements included stature, body mass, sum of 8 skinfold
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sites (ΣSkf8), estimated body fat (bf%), squat jump (SJ) and countermovement jump (CMJ), 5-, 10-
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and 20- m sprint time, upper and lower body strength (1RM) and Yo-Yo intermittent recovery test 2
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(Yo-Yo IR2). A multivariate analysis of variance (MANOVA) was used to determine seasonal and
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positional variations. Anthropometric variations were observed with an overall increase in
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participants’ body mass and a concomitant decrease in ΣSkf8 and bf% (−21.5%, p = 0.002, η2 = 0.15;
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−1.43 %, p = 0.004, η2 = 0.13). Performance variations showed improvements in sprint time over 5-
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(p = 0.001, η2 = 0.19) and 10-m (p = 0.008, η2 = 0.11), SJ (p = 0.013, η2 = 0.1), CMJ (p = 0.013, η2 =
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0.1) height and Yo-Yo IRT2 (p < 0.001, η2 = 0.34) noted from pre-season to mid-season. Significant
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anthropometric variations are observed between the pre-season and early in-season, meanwhile
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significant performance variations are observed between the pre-season and mid-season. Distinct
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positional variations are evident for both anthropometric and performance characteristics at all time
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points. Applied practitioners should consider these findings when implementing a seasonal training
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plan.
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Key words: Intermittent sport, Kinanthropometry, Physiology, Field testing
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Copyright ª 2017 National Strength and Conditioning Association
47 INTRODUCTION
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Gaelic football is a high-intensity intermittent invasion field sport with an unstable, stochastic nature
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(26). The sport has experienced a recent increased profile in the literature (7, 20, 33). Games last
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seventy minutes and involve bouts of high-speed running, jumping and tackling interspersed with
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brief recovery periods (17). Teams are made up of 15 players, with positional groups broken down
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into defenders (full-back and half-back), midfielders, and forwards (half-forward and full-forwards)
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(16). Playing positions place specific work-rate demands on players who require the necessary fitness
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to meet these demands (20, 25). Significant differences in global and demarcated distances covered by
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the central three positions are indicative of the unique role they play linking defensive and attacking
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play (20). Reductions in total distance covered and high speed running actions are observed following
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the first quarter of match play, with the middle three positions completing higher volumes of running
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in all quarters of match play (20).
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Assessment of body composition, particularly ‘body fat percentage’ (bf%) is often used as a
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default performance-profiling marker of Gaelic football players (10). Excess body fat is undesirable
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as it may compromise performance where body mass must be accelerated or lifted against gravity in
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aerial contests and running (9) (26). In both the research and applied Gaelic games setting, tissue
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adiposity has been estimated primarily from skinfold thickness (SFT) using equations, such as Durnin
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& Womersley (11) to equate bf%. Shortall, et al. (34) identified that there is a requirement for more
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contemporary data regarding anthropometric characteristics of elite Gaelic football players as
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the season when training loads were highest, with subsequent increases towards the end of the season,
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when training loads were lowest and match loads were highest (14).
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positional and seasonal variations are evident in Gaelic football. Anthropometric variations have previously been observed in rugby league, where skinfold thickness decreased in the early phases of
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Successful performance in Gaelic football requires an appreciation of the physiological
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demands of the game (8). Performance tests are undertaken to assess player characteristics, with re-
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testing undertaken to assess training adaptation (27). Horgan & Collins (16) observed a positional
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variation in squat jump (SJ) and countermovement jump (CMJ) scores in elite players. Recent
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evidence highlights the importance of acceleration ability at the elite level of Gaelic football with a
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positional variation evident, highlighting midfielders undertake the greatest number of accelerations
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with full-backs and full-forwards undertaking the least (19, 20, 28). Midfielders, half-backs and half-
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forwards also cover greater high-speed distances compared to full-backs and full-forwards, with
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similar trends observed in sprint distances (21). Krustrup et al., (19) determined the Yo-Yo
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intermittent recovery test (Yo-Yo IR) a reliable and sensitive test of an athlete’s ability to perform
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high-intensity intermittent exercise and can show changes in performance across a season, as well as
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across positions. Recent research has shown it is a reliable and valid assessment in Gaelic football
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(15). Collins & Doran (8) showed significant positional differences (p < 0.001) were evident in Yo-
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Yo IR2 performance with the middle three positional lines covering the greatest distances while the
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full-backs and full-forwards covered the least.
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Seasonal variation refers to changes in players’ anthropometric and performance
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characteristics, or both, throughout a typical competitive year. A competitive year may be divided in
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to ‘off-season’ and ‘in-season’; indicative of a decrease or increase in training load and competitions,
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respectively (18). The training arrangement could be regarded as ‘quasi-professional’, with players at
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the elite level required to train 2-3 times on the pitch per week, supplemented by 1-2 gym sessions per
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week. Performance testing has become widespread from underage teams all the way up to senior level (3). Variations are examined through repeated measurements of the anthropometric and performance
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characteristics and should incorporate a period before commencement of the competitive season
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(when there is a reduced training load), during the competitive season (when training load is
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increased) and the latter stages of competition (when training load is reduced while game load is
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increased). Variations have been documented in other field sports, such as rugby league (13) and
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soccer (5, 23), however, studies documenting variations anthropometric and performance
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characteristics of Gaelic football players are limited (15, 16, 34). Although previous studies
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measuring these characteristics have provided insight into the performance attributes of Gaelic
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football players, they have been limited to a single measurement, performed at varying periods of the
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competitive season (15, 16, 22, 24). Therefore, the objective of the current study was to examine
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variations in the anthropometric and performance characteristics of elite Gaelic football players across
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a competitive season. Additionally, this study aimed to determine variations with respect to playing
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position. Furthermore, this study is the first to provide a full view of the variations which take place
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across a competitive season in elite Gaelic football with respect to both anthropometric and
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performance characteristics. METHODS
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Experimental Approach to the Problem
Twenty-six elite Gaelic football players underwent measurements of standard anthropometric
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characteristics including stature, body mass, sum of eight skinfolds (ΣSkf8) and estimated body fat
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percentage (bf%). Performance characteristics including counter-movement jump (CMJ), CMJ peak
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power (CMJpeak), squat jump (SJ), 5-, 10-, 20-m sprint times, 1 repetition max deadlift (1RM DL), 1
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RM bench press (1RM BP), and Yo-Yo IR2 distance were measured. Data collection took place at
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three separate testing sessions across the season; pre-season (November), early in-season (January)
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and mid-season (March).
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midfield, half-forward, full forward) to allow for comparisons across positions (21), see Table 1. It
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was hypothesised that the greatest performance variations exist between the start of pre-season and
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Players were categorized according to position (full-back, half-back,
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early in-season, with greater variations in anthropometric characteristics observed between pre-season
and mid-season.
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Participants Following ethical approval by the local Research Ethics Committee and informed consent,
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twenty-six (n = 26), elite inter county footballers (mean ± SD age 26.6 ± 6 years, height 183.5 ± 7.4
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cm, body mass 85.4 ± 10.2 kg), playing in Division 1 of the National Football League participated in
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the study. When categorised by position the participants consisted of 5 full-backs, 6 half-backs, 5
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midfielders, 5 half-forwards and 5 full-forwards. ** INSERT TABLE 1 NEAR HERE **
131 Procedures
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All tests were conducted in the same venue to remove external interferences, with
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anthropometric assessments preceding performance assessments. Testing took place at the same time
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of day to minimize the effects of circadian variations on the variables measured (25). Prior to testing,
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participants were provided with nutrition and hydration strategies to optimise performance.
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Anthropometry: Anthropometric measurements were taken in accordance with the standards
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of the International Society for the Advancement of Kinanthropometry (ISAK). Stature and body
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mass were measured using a SECA stadiometer and digital weighing scales (SECA Instruments Ltd,
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Hamburg, Germany). Estimations of body fat percentage (bf%) were determined by measuring
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subcutaneous fat tissue in millimetres at eight sites (biceps, triceps, subscapular, iliac crest, supra-
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spinale, abdomen, front thigh and medial calf) using Harpenden skin-fold callipers (Harpenden
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Instruments Ltd, England). The bf% was determined using the Reilly estimation equation (28). A
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technical error of measurement was taken from all participants and was less than 3 %, which is within
the acceptable measurement error (1).
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Performance: Lower-limb power was assessed using the highest value obtained from three
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attempts of a squat jump (SJ) (participants squatted down until thighs were parallel with the floor and
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paused for 3 s, before jumping as high as possible), while maximum vertical jump height was
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determined using the highest value of three attempts of a counter-movement jump (CMJ) (4) with
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assessments were performed on a Takei digital jump reader (Takei, Japan). Counter-movement jump
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peak power (CMJpeak) was determined from the equation of Sayers et al. (30). Participants’ sprint
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times were measured over 20 m, with timing gates (Powertimer, Newtest, Oy, Finland) placed at 5-,
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10- and 20-m. Participants started from stationary and in their own time sprinted to the end of the
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outlined track and the quickest of three attempts, with 5 mins rest between attempts, was taken. Upper
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and lower body strength was determined with a 1 repetition maximum bench press (1 RM BP) and
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hexagonal-bar deadlift (1 RM DL) (32). Players’ ability to perform high-intensity intermittent
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exercise was assessed using the Yo-Yo IR2. The Yo-Yo test is a suitable test as it involves
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movements similar to those experienced during game play (2,18). Power and speed tests preceded
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cardio-respiratory fitness tests in the testing order.
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Statistical Analysis
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Descriptive statistics are presented as means ± standard deviations (± SD) and were calculated
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for each data collection session as well as for all positional categories. A multivariate analysis of
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variance (MANOVA) with position as the fixed factor, with a Fisher’s LSD post-hoc test was
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performed using Statistical Package for Social Sciences software (SPSS Version 22 for Windows 10,
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Chicago, IL). Significance was set at P ≤ 0.05. Due to the limited sample size in each position,
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estimates of effect size (37) were also undertaken using a partial eta-squared (η2p) and categorised
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according to Cohen (6). A η2p of 0.2, 0.5, 0.8 or 1.3 was considered small, moderate, large and very
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large difference, respectively.
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RESULTS
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Anthropometric
There was a significant main effect for time of season on ΣSkf8 (F2, 63 = 5.5, p = 0.006, η2 =
0.15) and bf% (F2, 63 = 4.7, p = 0.012, η2 = 0.13), see Figure 1.
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** INSERT FIGURE 1 NEAR HERE **
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There was a significant main effect for position on player height (F4, 63 = 11.4, p < 0.001, η2 = 0.42)
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body mass (F4, 63 = 5.18, p = 0.001, η2 = 0.25), ΣSkf8 (F4, 63 = 9.11, p < 0.001, η2 = 0.37) and bf% (F4, 63
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= 10.4, p < 0.001, η2 = 0.4). Midfield players were significantly taller in comparison to all other
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positions (p < 0.05) with significantly greater body mass compared to half backs (p = 0.003) and half
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forwards (p = 0.009). Full forwards were significantly heavier compared to half backs (p = 0.001) and
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half forwards (p = 0.002) and presented with the highest ΣSkf8, significantly different from half-
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backs, midfielders and half-forwards (p < 0.001; p = 0.038; p < 0.001, respectively), see Table 2. Full
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forwards and full backs had the highest bf%, significantly different compared to half backs (both p
