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Successful performance in competitive swimming requires a swimmer to maximise propulsion and minimise drag, which can be assessed using instantaneous swimming velocity. Many systems exist to quantify velocity, and therefore, it is important to understand the agreement between systems. This study examined the agreement between an automated video-based system and a tethered system to measure instantaneous velocity. Twenty-two competitive swimmers (state level or higher) completed 25 m of each stroke at maximal intensity. The tethered speedometer was attached to the swimmer's waist, while videos of each trial were recorded. The swimmer's head was then automatically tracked using proprietary software, and instantaneous velocity was determined from each system. Bland-Altman plots showed good agreement between the two systems in backstroke (95% Limits of Agreement (LOA): -0.24-0.26 m.s-1) and freestyle (95% LOA: -0.36-0.38 m.s-1) but poorer agreement in butterfly (95% LOA: -0.51-0.53 m.s-1) and breaststroke (95% LOA: -0.88-0.92 m.s-1). The root mean square error was higher in butterfly (0.27 m.s-1) and breaststroke (0.46 m.s-1) compared to backstroke (0.13 m.s-1) and freestyle (0.19 m.s-1). Results demonstrated that the two systems are comparable for measuring instantaneous swimming velocity; however, larger discrepancies are evident for butterfly and breaststroke.

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Trial matches are frequently used for team preparation in rugby league competitions, making it essential to understand the demands experienced to assess their specificity to actual competition. Consequently, this study aimed to compare the activity demands between pre-season trial matches and early in-season rugby league matches. Following a repeated-measures observational design, 39 semi-professional, male rugby league players from two clubs were monitored using microsensors during two trial matches and the first two in-season matches across two consecutive seasons. Total distance, average speed, peak speed, absolute and relative high-speed running (HSR; > 18 km · h-1) and low-speed running (LSR; < 18 km · h-1) distance, as well as absolute and relative impacts, accelerations (total and high-intensity > 3 m · s-2), and decelerations (total and high-intensity < -3 m · s-2) were measured. Linear mixed models and Cohen's d effect sizes were used to compare variables between match types. Playing duration was greater for in-season matches (p < 0.001, d = 0.64). Likewise, higher (p < 0.001, d = 0.45-0.70) activity volumes were evident during in-season matches indicated via total distance, HSR distance, LSR distance, total accelerations, high-intensity accelerations, total decelerations, and high-intensity decelerations. Regarding activity intensities, a higher average speed (p = 0.008, d = 0.31) and relative LSR distance (p = 0.005, d = 0.31) only were encountered during in-season matches. Despite players completing less volume, the average activity intensities and impact demands were mostly similar between trial and early in-season matches. These findings indicate trial matches might impose suitable activity stimuli to assist players in preparing for early in-season activity intensities.

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PURPOSE: To examine the effect of match schedule on self-reported wellness and sleep in rugby union referees during the 2019 Rugby World Cup. METHODS: Following an observational design, 18 international-level male referees participating in the 2019 Rugby World Cup completed a daily questionnaire to quantify wellness status (sleep quality, mood, stress, fatigue, muscle soreness, and total wellness) and sleep characteristics (bedtime, wake-up time, and time in bed) from the previous night across the tournament. Linear mixed models and effect sizes (Hedges gav) assessed differences in wellness and sleep characteristics between prematch and postmatch days surrounding single-game and 2-game congested match schedules (prematch1, postmatch1, prematch2, and postmatch2 days). RESULTS: During regular schedules, all self-reported wellness variables except stress were reduced (gav = 0.33-1.05, mean difference -0.32 to -1.21 arbitrary units [AU]) and referees went to bed later (1.08, 1:07 h:min) and spent less time in bed (-0.78, 00:55 h:min) postmatch compared with prematch days. During congested schedules, only wellness variables differed across days, with total wellness reduced on postmatch1 (-0.88, -3.56 AU) and postmatch2 (-0.67, -2.70 AU) days, as well as mood (-1.01, -0.56 AU) and fatigue (-0.90, -1.11 AU) reduced on postmatch1 days compared with prematch days. CONCLUSION: Referees were susceptible to acute reductions in wellness on days following matches regardless of schedule. However, only single-game regular match schedules negatively impacted the sleep characteristics of referees. Targeted strategies to maximize wellness status and sleep opportunities in referees considering the match schedule faced should be explored during future Rugby World Cup competitions.

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Purpose: The aim of this study was to investigate the effects of an above real-time video-based training intervention on Australian football umpire decision-making skill. Methods: Three groups completed two testing sessions, either side of a five-week, video-based training intervention either in real time (100% speed), above real time (150% speed) or control (no training) condition. Testing included two parts: resting included 25 video clips 10 of Australian football match footage, presented in real time with participants resting; exercise included a separate 25 clips also presented at real time, during a 10 × 300 m run test. Tests were repeated within two weeks following training. Results: Decision-making accuracy significantly improved (p = .043) for the real time training group in the exercise test. There were no improvements in control or above real-time training groups in the exercise test. No significant differences were observed for decision-making accuracy in the 15 resting test for all groups. Conclusion: Above real-time video may not develop decision-making skills more effectively than real-time video for amateur Australian football umpires. For this cohort, the faster presentation of video may result in the umpires missing important perceptual cues. Real-time video-based training appears to be more beneficial for amateur officials than 150% above real-time speed.

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Athlete chronotype has been documented to underpin diurnal variations in skill execution across various team sports. However, no research has explored the effects of athlete chronotype on basketball-specific skills at different times of the day. Therefore, the aim of this study was to explore diurnal variations in basketball shooting accuracy according to chronotype. Professional, male basketball players (n = 13) completed a Morningness- Eveningness Questionnaire and were categorised into chronotypes using a tertile split technique (morning-types: n = 4; neither-types: n = 4; evening-types: n = 5). Players completed separate trials of a shooting accuracy test in the morning (08:00-09:30h) and afternoon (15:00-16:30h) with each trial consisting of 20 shots attempted from four court locations at either two- or three-point distances and one-shot location from the free-throw line (100 shots in total). Each shot attempt was scored using a 0-3-point scale with higher scores awarded to more accurate shots. Non-significant (p >0.05) differences in shooting scores were evident between morning and afternoon trials for each chronotype group, with small-large effects in shooting scores favouring the morning across groups. Moreover, non-significant (p >0.05) differences in shooting scores were apparent between chronotype groups in the morning (small-large effects) and afternoon (moderate-large effects). Shooting accuracy appears to remain consistent across morning and afternoon performances irrespective of player chronotype in a professional basketball team, suggesting coaches may not need to schedule training sessions involving shooting tasks at specific times of the day to optimise shooting accuracy in players.

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OBJECTIVES: The aims of the present study were to (1) quantify sleep behaviours of soccer referees and (2) compare sleep behaviours between nights before training, before matches, and after matches. METHODS: Fourteen professional soccer referees from the A-League (mean±SD; age 34 ± 4 years; sex: 11 males, 3 females) participated in this observational study. Referees' sleep behaviours were examined using sleep diaries and wrist activity monitors for 31 consecutive nights during the 2018-2019 A-League season. Separate linear mixed models were conducted to assess differences in sleep behaviours between nights before training, before matches, and after matches. RESULTS: On average, referees did not obtain recommended sleep durations across the in-season (mean±SD sleep duration: 6.4 h ± 0.7 h). Referees went to bed later, spent less time in bed, and slept significantly less post-matches compared to pre-training and pre-match nights (p< 0.05). CONCLUSIONS: Referees were particularly susceptible to inadequate sleep on nights following training and matches. The findings related to poor sleep behaviours highlight the importance of implementing monitoring systems to understand the sleep behaviours of referees, with further research encouraged to ascertain the efficacy of various sleep hygiene practices to optimise sleep in this population.

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Accuracy and test-retest reliability were assessed for two devices, PUSH Band 2.0 (PUSH) and Speed4lifts. Two identical sessions were performed 6-8 days apart. Twenty rugby league players performed three repetitions with 20%, 40%, 60% and 80% of estimated one repetition maximum for back squat (BS), front squat (FS), and bench press (BP). Velocity was recorded using PUSH, Speed4lifts and 3D motion analysis system (gold standard). Passing-Bablok regression analysis assessed agreement of velocity measures with the gold standard. Intraclass correlation coefficients (ICC) and coefficients of variation (CV) assessed test-retest reliability. PUSH and Speed4lifts were accurate for BS velocities <1.00 m/s and FS velocities <0.65 m/s. PUSH was accurate for BP velocities <0.65 m/s. Speed4lifts was accurate for BP velocities between 0.65-1.00 m/s. PUSH was reliable at all loads (ICC = 0.79-0.92; CV = 2.63-6.89%) except for 20% FS and BP (ICC = 0.49-0.64; CV = 3.13-3.62%). Speed4lifts was reliable at all loads (ICC = 0.70-0.96; CV = 2.57-4.26%) except for 20% BP (ICC = 0.59; CV = 4.59%). These results suggest that both devices are unsuitable for measuring the velocity of BS, FS and BP at faster velocities and at lighter loads.

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BACKGROUND: Sleep and wellness outcomes have been explored in elite netball athletes, but research examining these outcomes in sub-elite athletes is lacking despite high participation rates at the sub-elite level. The aim was to investigate the impact of the scheduling of games over consecutive days during a truncated four-round netball competition on the sleep and wellness outcomes of sub-elite netballers. METHODS: A total of 12 female, sub-elite netball players were examined via sleep outcomes, stress, fatigue, mood, muscle soreness, and overall wellness on the night before, the night of, and for two nights after games during a four-round truncated competition. Linear mixed models examined changes for variables across days around game day. RESULTS: Bedtime (P=0.038), wake time (P=0.001), fatigue (P=0.003), and muscle soreness (P<0.001) differed according to game status (i.e., pre-game days, game days, and post-game days). Bedtime was later on game days compared to pre-game days, and wake-up time was later on post-game days than pre-game days. Fatigue and muscle soreness were greater the day after the game, compared to days before the game. Over the four rounds, bedtime (P=0.027) and wake-up time (P<0.001) tended to be later, while wellness did not change. CONCLUSIONS: These data may help guide coaching staff to plan training and travel arrangements during truncated multi-week competitions.

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Sport-specific skills display diurnal variation across various team sports such as badminton and tennis serving accuracy and soccer dribbling, volleying, and chipping execution. However, the effects of athlete chronotype on in-game sport-specific skill performance according to time of day across team sports is not well understood. Therefore, the aim of this study was to identify the effect of player chronotype on in-game basketball performance during evening games. Professional male basketball players (n = 11) completed a morningness-eveningness questionnaire and were categorized according to chronotype (morning-type: n = 4; neither-type: n = 6; evening-type: n = 1). Box score data from the 2019/20 season were utilized to determine individual in-game performance during evening games played after 18:00 h. Composite metrics (i.e., effective field goal percentage, offensive rating, defensive rating, and player efficiency) were used as indicators of player performance. Non-significant (p ≥ 0.21) differences were evident between M-types and N-types for most performance measures. Small to very large effects were observed in the number of rebounds favoring M-types, and three-point shots attempted and made, assists, and steals favored N-types. In-game performance appeared to not be affected by chronotype (i.e., M-type vs. N-type) in evening games among professional male basketball players. The lack of observed effect between chronotype and in-game performance suggest coaching staff may not need to consider player chronotype when developing a match strategy or assigning player roles if largely dealing with M-types and N-types. However, to ensure the greatest specificity, coaching staff may endeavor to schedule habitual training times in line with that of competition in an effort to align player circadian rhythms to games.

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Limited research has examined the demands of backward locomotion at various speeds using common load monitoring metrics in team sport athletes. Consequently, this study compared the external and internal loads between backward and forward locomotion during intermittent exercise in team sport athletes. Semi-professional, male rugby league players (n = 29) completed the same exercise protocol on two occasions in backward and forward directions. On each occasion, participants performed separate 20 m trials at self-selected walking, jogging, running, and sprinting speeds and then completed a 15 min modified Loughborough intermittent shuttle test (mLIST). Common external and internal load metrics were gathered across testing. Faster speeds (p < 0.001) were attained at all speeds during forward locomotion in the 20 m trials. Non-significant differences in accumulated PlayerLoadTM were found between directions across the mLIST; however, higher relative (per min) PlayerLoadTM (p < 0.001) was apparent during backward locomotion when walking and during forward locomotion when sprinting during the mLIST. RPE and mean heart rate were higher (p < 0.001) during backward locomotion across the mLIST. These data highlight the unique loading patterns experienced during backward locomotion and suggest practitioners should consider the discernment in loading imposed between backward and forward locomotion when measuring athlete demands using common metrics.

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This study aimed to assess the level of transfer of two reliable and valid video modes to in-game decision-making performance. Two video-based tests of 25 clips each (360°VR and match broadcast vision) assessed off-field decision-making accuracy in elite Australian football umpires (n=21). Game performance was assessed across four games for each participant, classified into two groups based on this measure; "highly skilled" or 'skilled'. Decision-making was assessed for correct, missed and unwarranted decisions in video-based tests and in-game assessments. Independent t-tests analysed differences between highly skilled and skilled in-game decision-makers for each test. Correlations also compared experience and in-game with video-based test decision-making performance. For both video-based tests, there were no significant differences between highly skilled and skilled in-game decision-makers, nor any significant correlations. Officials who made less unwarranted decisions in-game (highly skilled) made significantly less unwarranted decisions in the match broadcast test. There was a significant correlation between experience and 360°VR correct decision-making. Neither video-based test had the sensitivity to discriminate between elite officials, potentially due to the third-person perspective (match broadcast task) or sub-elite players presented (360°VR). Optimising the representativeness of off-field tasks through including similar constraints to performance environments is an important consideration for researchers and practitioners.

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Objectives: While sleep research in athletes is extensive, no research has investigated sleep in sports officials during a competitive season. This study explored the (a) self-reported quantity and quality of sleep obtained by sports officials according to the time of competition (day or evening) and (b) impact of reduced sleep on perceived decision-making ability. Design: Sports officials (n = 371) from various sporting codes completed an online questionnaire that evaluated self-reported sleep quantity and quality on habitual nights, before competition, and after competition, as well as perceived decision-making constructs. Results: With sleep restriction defined as less than 7 h of sleep, mixed-effects logistic regression revealed that the estimated probability of reporting reduced sleep quantity increased (p< .05) on habitual nights (0.58), before competition (0.48), and after competition (0.56). The estimated probability of reporting poor sleep quality was 0.01-0.04 across all nights. When considering time of competition (day or evening), reduced sleep quantity was experienced after evening competition (odds ratio [OR] = 3.33, p < .05), while poorer sleep quality (p< .05) was experienced following day (OR = 2.1) and evening (OR = 12.46) competition compared to habitual nights. Furthermore, the impact of reduced sleep on perceived decision-making constructs was negative, with the estimated probability of reporting impaired perceived decision-making between 0.13 and 0.21. Conclusion: Overall, sports officials are vulnerable to reduced quantity and quality of sleep before and after competition, with impaired perceived decision-making ability following nights of less than average sleep.

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OBJECTIVES: Back squat mean concentric velocity (MV) and countermovement jump (CMJ) performance were examined in sub-elite rugby league players post-match to monitor changes in neuromuscular status (NMS) from baseline. Relationships between changes in back squat MV and CMJ performance variables were used to compare back squat MV to an established method to monitor NMS. DESIGN: Longitudinal observational design. METHODS: 18 male sub-elite rugby league players (mean±SD, 20.5±2.4 yr; 180.0±6.7cm; 93.3±11.2kg) performed 3 repetitions of CMJ and back squat with an individualised, pre-determined load at -2h (baseline), +30min, +24h, and +48h in relation to a match. Back squat MV, CMJ height, CMJ peak power, and CMJ peak velocity were measured with a linear position transducer. RESULTS: Significant (p<0.05), small to large decreases (ES=0.52-1.24) were observed in back squat MV up to +48h post-match. Significant (p<0.05), small to moderate decreases (ES=0.52-0.70) in CMJ height were also observed up to +24h post-match, returning to baseline at +48h. CMJ peak power and peak velocity post-match changes were not significant compared to baseline (p>0.05). Significant positive correlations were found between changes in back squat MV and CMJ height at +30min (r=0.59; p=0.009) and +48h (r=0.51; p=0.03). CONCLUSIONS: These findings suggest back squat MV may be a suitable alternative or addition to CMJ testing for monitoring NMS in rugby league players.

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OBJECTIVES: Quantify the on-field movements, heart rate and perceived exertion (RPE) of lead referees during Rugby World Cup matches. DESIGN: Descriptive, observational. METHODS: On-field movements (distance, average speed, high-speed running [>5ms-1]), heart rate and RPE of 11 lead referees were assessed during 29 Rugby World Cup (Knockout and Pool) matches. Average speed and heart rate were assessed using rolling average methods (1-10min epochs). Linear mixed models and Cohen's effect size (d) were used to compare match variables between Pool and Knockout matches. RESULTS: Referees covered on average 6674±566m (65.8±6.3mmin-1), with 586±290m in high-speed running. Mean heart rate was 146±9 beatsmin-1, summated-heart-rate-zones was 235±36AU, and sRPE load was 577±205AU. A large reduction (d=1.40) in high-speed running distance and moderate reductions in average speed over 1 (d=0.81) and 2min (d=0.83) epochs were found during Knockout, compared to Pool matches. Differences between Pool and Knockout matches on other measures of referee movement, heart rate and RPE were trivial. CONCLUSIONS: This is the first investigation to examine the effect of competition stage on rugby union referees on-field performance. Individual and match contextual factors may explain the reduction in high-speed running during Knockout matches, however more detailed examination of the factors influencing referee performance is required for greater insight into the key performance indicators in rugby union. Nonetheless, these data provide practitioners with knowledge to assist in preparation of rugby union referees for future Rugby World Cup competitions.

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ABSTRACT: Elsworthy, N, Callaghan, DE, Scanlan, AT, Kertesz, AHM, Kean, CO, Dascombe, BJ, and Guy, JH. Validity and reliability of using load-velocity relationship profiles to establish back squat 1 m·s-1 load. J Strength Cond Res 35(2): 340-346, 2021-Although measuring movement velocity during resistance exercise is being increasingly used to monitor player readiness for competition in team sports, the validity and reliability of using set target velocities has not been examined. This study examined test-retest reliability of the load-velocity relationship during the back squat to predict loads corresponding to a mean velocity of 1 m·s-1 (V1Load), test-retest reliability of mean concentric velocity at V1Load, and criterion validity of mean concentric velocity at V1Load. Twenty-seven resistance-trained male rugby league players completed 2 testing sessions on separate days to establish individualized back squat load-velocity relationship profiles (30, 40, 60, and 80% estimated 1 repetition maximum). Velocity during the back squat was assessed at each load and V1Load derived using individualized linear regression equations. A subset of subjects (n = 18) also performed the back squat at predicted V1Load to examine the test-retest reliability and compare the mean concentric velocity with the predicted target of 1 m·s-1. The mean concentric velocity was consistent across all loads during load-velocity relationship testing (p > 0.05, intraclass correlation coefficient [ICC] ≥0.75, coefficient of variation [CV] ≤5.7%, effect size [ES] ≤0.27), and for predicting V1Load (p = 0.11, ICC = 0.95, CV = 3.9%, ES = 0.11). The mean concentric velocity at V1Load was reliable (ICC = 0.77; CV = 2.6%; ES = 0.39) and not significantly different (p = 0.21) to the target velocity, supporting criterion validity. Individualized load-velocity profiles for the back squat can accurately predict V1Load, and subsequent use of V1Load to assess back squat velocity is valid and reliable. Using V1Load to assess changes in back squat velocity may have application in measuring changes in strength and power or readiness to train.

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PURPOSE: To examine correlations between peak force and impulse measures attained during the isometric midthigh pull (IMTP) and basketball-specific sprint and jump tests. METHODS: Male, adolescent basketball players (N = 24) completed a battery of basketball-specific performance tests. Testing consisted of the IMTP (absolute and normalized peak force and impulse at 100 and 250 ms); 20-m sprint (time across 5, 10, and 20 m); countermovement jump (CMJ; absolute and normalized peak force and jump height); standing long jump (distance); and repeated lateral bound (distance). Correlation and regression analyses were conducted between IMTP measures and other attributes. RESULTS: An almost perfect correlation was evident between absolute peak force attained during the IMTP and CMJ (r = .94, R2 = 56%, P < .05). Moderate to very large correlations (P < .05) were observed between IMTP normalized peak force and 5-m sprint time (r = -.44, R2 = 19%), 10-m sprint time (r = -.45, R2 = 20%), absolute (r = .57, R2 = 33%), normalized (r = .86, R2 = 73%) CMJ peak force, and standing long-jump distance (r = .51, R2 = 26%). Moderate to very large correlations were evident between impulse measures during the IMTP and 5-m sprint time (100 ms, r = -.40, R2 = 16%, P > .05) and CMJ absolute peak force (100 ms, r = .73, R2 = 54%; 250 ms, r = .68, R2 = 47%; P < .05). CONCLUSIONS: The IMTP may be used to assess maximal and rapid force expression important across a range of basketball-specific movements.

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OBJECTIVES: To examine the reliability, construct validity and ecological validity of 360° VR and match broadcast footage for off-field decision-making assessment in Australian football umpires. DESIGN: Validation assessments with test re-test reliability. METHODS: Two video-based tests of 60 clips each were developed to assess Australian football umpire decision-making, including 360° video of small-sided Australian football games and match broadcast footage of AFL games. Elite (n = 13) and amateur (n = 15) umpires participated in two testing sessions, in a randomised, counterbalanced design. Test re-test reliability was assessed using Cohen's Kappa for individual clips and Intraclass Correlation Coefficients for test scores. Video tests were assessed for construct validity. Ecological validity of the decision-making processes was assessed for each method. RESULTS: 31 clips met the minimum Kappa criteria for the 360° VR test and 28 clips for match broadcast. Results indicated strong reliability for the 360° VR (ICC = 0.89) and match broadcast (ICC = 0.89) tests. For both video modes, elite umpires performed significantly better in decision-making accuracy than amateur (p < 0.05). For ecological validity of the decision-making processes, 360° VR was rated significantly higher than match broadcast vision (p < 0.05) overall. CONCLUSIONS: This is the first study to examine the reliability and validity of 360° VR footage as an off-field decision-making assessment tool in sport. As match broadcast vision is commonly used to assess decision-making in athletes and officials, results suggest that 360° VR is also an appropriate assessment tool. Although both video modes demonstrate similar reliability and construct validity, 360° VR was considered more specific to in-game decision-making processes, suggesting stronger ecological validity.

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Existing methods for developing decision-making skill for Australian football umpires separate the physical and perceptual aspects of their performance. This study aimed to determine the efficacy of incorporating video-based decision-making training during high-intensity interval training sessions, specific for Australian football umpires. 20 amateur Australian football umpires volunteered to participate in a randomised control trial. Participants completed an 8-week training intervention in a conditioning only (CON; n=7), combined video-based training and conditioning (COM; n=7), or separated conditioning and video-based training (SEP; n=6) group. Preliminary and post-testing involved a Yo-Yo Intermittent Recovery Test (Yo-YoIR1), and 10x300m run test with an Australian football specific video-based decision-making task. Overall, changes in decision-making accuracy following the intervention were unclear between groups. SEP was possibly beneficial compared to COM in Yo-YoIR1 performance, whereas CON was likely beneficial compared to COM in 10x300m sprint performance. There was no additional benefit to completing video-based training, whether combined with, or separate to physical training, suggesting that this was not an optimal training method. For video-based training to be an effective decision-making tool, detailed feedback should be incorporated into training. It is recommended that longer conditioning and video-based training interventions be implemented to determine training effectiveness.

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PURPOSE: To examine the movement and physiological demands of rugby union officiating in elite competition. METHODS: Movement demands of 9 elite officials across 12 Super Rugby matches were calculated, using global positioning system devices. Total distance (in m), relative distance (in m·min-1), and percentage time spent in various speed zones were calculated across a match. Heart-rate (HR) responses were also recorded throughout each match. Cohen d effect sizes were reported to examine the within-match variations. RESULTS: The total distance covered was 8030 (506) m, with a relative distance of 83 (5) m·min-1 and with no differences observed between halves. Most game time was spent at lower movement speeds (76% [2%]; <2.0 m·s-1), with large effects for time spent >7.0 m·s-1 between halves (d = 2.85). Mean HR was 154 (10) beats·min-1 (83.8 [2.9]%HRmax), with no differences observed between the first and second halves. Most game time was spent between 81%HRmax and 90%HRmax (40.5% [7.5%]) with no observable differences between halves. Distances covered above 5.1 m·s-1 were highest during the first 10 min of a match, while distance at speeds 3.7 to 5 m·s-1 decreased during the final 10 min of play. CONCLUSIONS: These findings highlight the highly demanding and intermittent nature of rugby union officiating, with only some minor variations in physical and physiological demands across a match. These results have implications for the physical preparation of professional rugby union referees.

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Cust, EE, Elsworthy, N, and Robertson, S. Analysis of training loads in elite under 18 Australian rule football players. J Strength Cond Res 32(9): 2521-2528, 2017-Differences in training loads (TLs) between under 18 (U18) Australian rules football (AF) state academy-selected and state academy-nonselected players were investigated. Players were categorized relating to their highest representative level: state academy-selected (n = 9) and TAC cup-level players (n = 38). Data were obtained from an online training-monitoring tool implemented to collect player training and match information across a 20-week period during the regular season. Parameters modeled included AF skills, strength, and other sport training sessions. Descriptive statistics (mean ± SD) and between-group comparisons (Cohen's d) were computed. A J48 decision tree modeled which TL variables could predict selection level. Pooled data showed 60% of weekly training duration consisted of AF training sessions. Similar AF TL were reported between state academy and TAC cup players (1,578 ± 1,264 arbitrary units (AU) vs. 1,368 ± 872 AU; d = 0.05). Although higher TLs were reported for state-selected players comparative with TAC cup in total training (d = 0.20), core stability (d = 0.36), flexibility (d = 0.44), on-feet conditioning (d = 0.26), and off-feet conditioning (d = 0.26). Decision tree analysis showed core stability duration and flexibility TL, the most influential parameters in classifying group selection (97.7% accuracy TAC cup level; 35.8% accuracy state academy level). Insights of U18 AF players' weekly training structures, loads, and characteristics of higher achieving players are provided. This study supports the application of training diaries and session rating of perceived exertion for TL monitoring in junior athletes.

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