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Measurement Properties of an Adductor Strength-Assessment System in Professional Australian Footballers

Samuel Ryan, Thomas Kempton, Emidio Pacecca, and Aaron J. Coutts

Purpose: To examine the measurement properties of an adductor strength-assessment system in professional Australian footballers. Methods: Observational, longitudinal design. Test–retest reliability data were collected from 18 professional Australian footballers from 1 club on the same day during the 2017 Australian Football League season. Week-to-week variation data were collected on 45 professional Australian footballers from 1 club during the same season at 48, 72, and 120 h postmatch (rounds 1–23). Players lay beneath a GroinBar hip-strength testing system in supine position with their knee joints at an angle of 60°. Force (in newtons) was extracted for the left and right limbs of each player and a pain score from 0 to 10 (0 = no pain, 10 = maximum pain) was provided. Coefficient of variation (CV) and smallest worthwhile change were calculated on test–retest data. Signal-to-noise ratio was calculated for each major time point. Mean difference between force scores in a subgroup of players with and without groin pain (n = 18) was collected as evidence of construct validity for the system. Results: Test CV was 6.3% (4.9–9.0%). CV exceeded the smallest worthwhile change on both limbs. Intraclass correlation coefficient was .94. Signal-to-noise ratio ranged from 1.6 to 2.6 on average for 48, 72, and 120 h postmatch. Groin pain had a very likely moderate negative effect on adductor strength (effect size: 0.41). Conclusions: The system possesses greater measurement precision than dynamometry and sphygmomanometer adductor strength-assessment methods in professional Australian footballers. Increased groin pain reduced groin squeeze force production. Practitioners may interpret changes exceeding 6.3% in adductor strength as real.

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Internal and External Training Load: 15 Years On

Franco M. Impellizzeri, Samuele M. Marcora, and Aaron J. Coutts

Exercise is a stressor that induces various psychophysiological responses, which mediate cellular adaptations in many organ systems. To maximize this adaptive response, coaches and scientists need to control the stress applied to the athlete at the individual level. To achieve this, precise control and manipulation of the training load are required. In 2003, the authors introduced a theoretical framework to define and conceptualize the measurable constructs of the training process. They described training load as having 2 measurable components: internal and external load. The aim of this commentary is to extend, clarify, and refine both the theoretical framework and the definitions of internal and external training load to avoid misinterpretation of this concept.

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Quantifying Physical Demands in the National Basketball Association—Challenges Around Developing Best-Practice Models for Athlete Care and Performance

Blake D. McLean, Donald Strack, Jennifer Russell, and Aaron J. Coutts

The National Basketball Association (NBA) has an extremely demanding competition schedule, requiring its athletes to compete in 82 regular-season games over a 6-mo period (∼3.4 games/wk). Despite the demanding schedule and high value of athletes, there is little public information on the specific game and training demands required to compete in the NBA. Although provisions in the NBA collective-bargaining agreement allow for research designed to improve player health and broaden medical knowledge, such information is sparse in the available literature. In relation to the physical demands of the NBA, the current lack of information likely results from multiple factors including limited understanding of (basketball-related) emerging technologies, impact of specific league rules, and steps taken to protect players in the age of Big Data. This article explores current limitations in describing specific game/training demands in the NBA and provides perspectives on how some of these challenges may be overcome. The authors propose that future collaborations between league entities, NBA clubs, commercial partners, and outside research institutions will enhance understanding of the physical demands in the NBA (and other health- and performance-related areas). More detailed understanding of physical demands (games, practices, and travel) and other health-related areas can augment player-centered decision making, leading to enhanced player care, increased availability, and improved physical performance.

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Combining Research With “Servicing” to Enhance Sport Performance

Shona L. Halson, Alan G. Hahn, and Aaron J. Coutts

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Factors Affecting Match Running Performance in Professional Australian Football

Samuel Ryan, Aaron J. Coutts, Joel Hocking, and Thomas Kempton

Purpose:

To examine the influence of a range of individual player characteristics and match-related factors on activity profiles during professional Australian football matches.

Methods:

Global positioning system (GPS) profiles were collected from 34 professional Australian football players from the same club over 15 competition matches. GPS data were classified into relative total and high-speed running (HSR; >20 km/h) distances. Individual player aerobic fitness was determined from a 2-km time trial conducted during the preseason. Each match was classified according to match location, season phase, recovery length, opposition strength, and match outcome. The total number of stoppages during the match was obtained from a commercial statistics provider. A linear mixed model was constructed to examine the influence of player characteristics and match-related factors on both relative total and HSR outputs.

Results:

Player aerobic fitness had a large effect on relative total and HSR distances. Away matches and matches lost produced only small reductions in relative HSR distances, while the number of rotations also had a small positive effect. Matches won, more player rotations, and playing against strong opposition all resulted in small to moderate increases in relative total distance, while early season phase, increased number of stoppages, and away matches resulted in small to moderate reductions in relative total distance.

Conclusions:

There is a likely interplay of factors that influence running performance during Australian football matches. The results highlight the need to consider a variety of contextual factors when interpreting physical output from matches.

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Accuracy and Validity of Commercially Available Kayak Ergometers

Thiago Oliveira Borges, Nicola Bullock, David Aitken, and Aaron J. Coutts

Methods:

This study compared 3 commercially available ergometers for within- and between-brands difference to a first-principle calibration rig.

Results:

All ergometers underestimated true mean power, with errors of 27.6% ± 3.7%, 4.5% ± 3.5%, and 22.5% ± 1.9% for the KayakPro, WEBA, and Dansprint, respectively. Within-brand ergometer power differences ranged from 17 ± 9 to 22 ± 11 W for the KayakPro, 3 ± 4 to 4 ± 4 W for the WEBA, and 5 ± 3 to 5 ± 4 W for the Dansprint. The linear-regression analysis showed that most kayak ergometers have a stable coefficient of variation (0.9–1.7%) with a moderate effect size.

Conclusion:

Taken collectively, these findings show that different ergometers present inconsistent outcomes. Therefore, we suggest that athlete testing be conducted on the same ergometer brand, preferably the same ergometer. Optimally, that ergometer should be calibrated using a first-principle device before any athlete testing block.

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Variability of GPS Units for Measuring Distance in Team Sport Movements

Denise Jennings, Stuart Cormack, Aaron J. Coutts, Luke J. Boyd, and Robert J. Aughey

Purpose:

To examine the difference in distance measured by two global positioning system (GPS) units of the same model worn by the same player while performing movements common to team sports.

Methods:

Twenty elite Australian football players completed two trials of the straight line movement (10, 20, 40 m) at four speeds (walk, jog, stride, sprint), two trials of the changes of direction (COD) courses of two different frequencies (gradual and tight), and five trials of a team sport running simulation circuit. To assess inter-unit variability for total and high intensity running (HIR) distance measured in matches, data from eight field players were collected in three Australian Hockey League (AHL) matches during the 2009 season. Each subject wore two GPS devices (MinimaxX v2.5, Catapult, Australia) that collected position data at 5 Hz for each movement and match trial. The percentage difference ±90% confidence interval (CI) was used to determine differences between units.

Results:

Differences (±90% CI) between the units ranged from 9.9 ± 4.7% to 11.9 ± 19.5% for straight line running movements and from 9.5 ± 7.2% to 10.7 ± 7.9% in the COD courses. Similar results were exhibited in the team sport circuit (11.1 ± 4.2%). Total distance (10.3 ± 6.2%) and HIR distance (10.3 ± 15.6) measured during the match play displayed similar variability.

Conclusion:

It is recommended that players wear the same GPS unit for each exercise session to reduce measurement error. The level of between-unit measurement error should be considered when comparing results from players wearing different GPS units.

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Changes in Core Temperature During an Elite Female Rugby Sevens Tournament

Mitchell J. Henderson, Bryna C.R. Chrismas, Christopher J. Stevens, Aaron J. Coutts, and Lee Taylor

Purpose: To characterize player core temperature (Tc) across a World Rugby Women’s Sevens Series tournament day (WRWSS) and determine the efficacy of commonly employed cold-water-immersion (CWI) protocols. Methods: Tc was measured in 12 elite female rugby sevens athletes across 3 games (G1–3) from day 1 of the Sydney WRWSS tournament. Symptoms of exertional heat illness, perceptual scales, CWI details, playing minutes, external-load data (measured by global positioning systems), and wet-bulb globe temperature (range 18.5°C–20.1°C) were also collected. Linear mixed models and magnitude-based inferences were used to assess differences in Tc between periods (G1–3 and warm-ups [WU]). Results: Average Tc was “very likely” lower (effect size; ±90% confidence limit −0.33; ±0.18) in G1 than in G2. Peak Tc was “very likely” (0.71; ±0.28) associated with increased playing time. CWI did not remove the accumulated Tc due to WU and match-play activity (∼1°C–2°C rise in Tc still present compared with Tc at WU onset for players ≥6-min match play). Conclusions: Elite WRWSS athletes experienced high Tc during WU (Tc peak 37.9–39.0°C) and matches (Tc peak 37.9–39.8°C), a magnitude known to reduce intermittent high-intensity physical performance (≥39°C). The CWI protocol resulted in players (≥6-min match play) with ∼1°C to 2°C raised Tc compared with Tc at WU onset.

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The Effect of Habitual Exercise on Respiratory-Muscle Function in Older Adults

Mark L. Watsford, Aron J. Murphy, Matthew J. Pine, and Aaron J. Coutts

Older adults’ participation in habitual exercise might be affected by alterations to respiratory mechanics such as decreased respiratory-muscle strength. This reduction can cause a decrease in efficiency of the ventilatory pump, potentially compromising exercise participation. This research examined the role of habitual exercise in respiratory-muscle function and the associated implications for exercise performance. Seventy-two healthy older adults (36 men, 64.9 ± 8.6 years, 177.2 ± 8.4 cm, 82.5 ± 11.9 kg; 36 women, 64.9 ± 9.5 years, 161.7 ± 6.4 cm, 61.6 ± 9.2 kg) undertook respiratory-function and walking-performance tests. Active men and women achieved higher scores than their inactive counterparts for all tests except spirometry, where no differences were evident. The results indicate that a significant amount of the elevated fitness level might be accounted for by increased endurance capacity of the inspiratory muscles. Inactive older individuals might be at risk for inadequate respiratory-muscle strength, so interventions should be considered.

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GPS Analysis of an International Field Hockey Tournament

Denise Jennings, Stuart J. Cormack, Aaron J. Coutts, and Robert J. Aughey

Purpose:

The purpose of this study was to investigate the influence of multiple games on exercise intensity during a world-class hockey tournament.

Methods:

15 players (mean ± SD age 27 ± 4 y, stature 179 ± 5 cm, body mass 77 ± 5 kg, and estimated VO2 64.2 ± 3.1 mL · kg−1 · min−1) competing in the Champions Trophy (CT). Global-positioning systems assessed total distance (TD), low-speed activity (LSA; 0.10–4.17 m/s), and high-speed running (HSR; >4.17 m/s) distance. Differences in movement demands (TD, LSA, HSR) between positions and matches were assessed using the effect size and percent difference ± 90% confidence intervals. Two levels of comparison were made. First, data from subsequent matches were compared with match 1, and, second, data from each match compared with a tournament average (TA).

Results:

In all matches, compared with game 1, midfielders performed less HSR distance. However, the amount of HSR did not decrease as the tournament progressed. When compared with the TA, defenders showed more variation in each match. All positions showed lower movement outputs when the team won by a large margin.

Conclusions:

It was possible for elite team-sport athletes to maintain exercise intensity when playing 6 matches in a period of 9 days, contrary to the only other investigation of this in elite male field hockey.