Search Results

You are looking at 1 - 10 of 15 items for

  • Author: Stuart J. Cormack x
  • Refine by Access: All Content x
Clear All Modify Search
Restricted access

Danielle T. Gescheit, Stuart J. Cormack, Machar Reid, and Rob Duffield

Purpose:

To determine how consecutive days of prolonged tennis match play affect performance, physiological, and perceptual responses.

Methods:

Seven well-trained male tennis players completed 4-h tennis matches on 4 consecutive days. Pre- and postmatch measures involved tennis-specific (serve speed and accuracy), physical (20-m sprint, countermovement jump [CMJ], shoulder-rotation maximal voluntary contraction, isometric midthigh pull), perceptual (Training Distress Scale, soreness), and physiological (creatine kinase [CK]) responses. Activity profile was assessed by heart rate, 3D load (accumulated accelerations measured by triaxial accelerometers), and rating of perceived exertion (RPE). Statistical analysis compared within- and between-days values. Changes (± 90% confidence interval [CI]) ≥75% likely to exceed the smallest important effect size (0.2) were considered practically important.

Results:

3D load reduced on days 2 to 4 (mean effect size ± 90% CI –1.46 ± 0.40) and effective playing time reduced on days 3 to 4 (–0.37 ± 0.51) compared with day 1. RPE did not differ and total points played only declined on day 3 (–0.38 ± 1.02). Postmatch 20-m sprint (0.79 ± 0.77) and prematch CMJ (–0.43 ± 0.27) performance declined on days 2 to 4 compared with prematch day 1. Although serve velocity was maintained, compromised postmatch serve accuracy was evident compared with prematch day 1 (0.52 ± 0.58). CK increased each day, as did ratings of muscle soreness and fatigue.

Conclusions:

Players reduced external physical loads, through declines in movement, over 4 consecutive days of prolonged competitive tennis. This may be affected by tactical changes and pacing strategies. Alongside this, impairments in sprinting and jumping ability, perceptual and biochemical markers of muscle damage, and reduced mood states may be a function of neuromuscular and perceptual fatigue.

Restricted access

Mitchell Mooney, Stuart Cormack, Brendan O’Brien, and Aaron J Coutts

Purpose:

The purpose of this study was to determine if Yo-Yo Intermittent Recovery level 2 (Yo-Yo IR2) and the number of interchange rotations affected the match activity profile of elite Australian footballers.

Method:

Fifteen elite Australian footballers completed the Yo-Yo IR2 before the beginning of the season and played across 22 matches in which match activity profiles were measured via microtechnology devices containing a global positioning system (GPS) and accelerometer. An interchange rotation was counted when a player left the field and was replaced with another player. Yo-Yo IR2 results were further split into high and low groups.

Results:

Players match speed decreased from 1st to 4th quarter, while average-speed (m/min: P = .05) and low-speed activity (LSA, <15 km/h) per minute (LSA m/min; P = .06) significantly decreased in the 2nd half. Yo-Yo IR2 influenced the amount of m/min, high-speed running (HSR, >15 km/h) per minute (HSR m/min) and accelerometer load/min throughout the entire match. The number of interchanges significantly influenced the HSR m/min and m/min throughout the match except in the 2nd quarter. Furthermore, the low Yo-Yo IR2 group had significantly less LSA m/min in the 4th quarter than the high Yo-Yo IR2 group (92.2 vs 96.7 m/min, P = .06).

Conclusions:

Both the Yo-Yo IR2 and number of interchanges contribute to m/min and HSR m/min produced by elite Australian footballers, affecting their match activity. However, while it appears that improved Yo-Yo IR2 performance prevents reductions in LSA m/min during a match, higher-speed activities (HSR m/min) and overall physical activity (m/min and load/min) are still reduced in the 4th quarter compared with the 1st quarter.

Restricted access

Stuart J. Cormack, Robert U. Newton, and Michael R. McGuigan

Purpose:

To examine the acute and short-term responses of variables obtained during a single countermovement jump (CMJ1); repeated countermovement jump involving 5 consecutive efforts without a pause (CMJ5); and cortisol, testosterone, and testos-terone-to-cortisol ratio (T:C) to an elite Australian Rules Football (ARF) match with a view to determining which variables may be most useful for ongoing monitoring.

Methods:

Twenty-two elite ARF players participating in a preseason cup match performed a CMJ1 and a CMJ5 and provided saliva samples 48 h before the match (48pre), prematch (Pre), postmatch, 24 h post (24post), 72 h post (72post), 96 h post (96post), and 120 h post (120post). The magnitude of change in variables at each time point compared with Pre and 48pre was analyzed using the effect size (ES) statistic.

Results:

A substantial decrement in the pre- to postmatch comparison occurred in the ratio of CMJ1 Flight time:Contraction time (ES −0.65 ± 0.28). Cortisol (ES 2.34 ± 1.06) and T:C (ES −0.52 ± 0.42) displayed large pre- to postmatch changes. The response of countermovement variables at 24post and beyond compared with pre-match and 48pre was varied, with only CMJ1 Flight time:Contraction time displaying a substantial decrease (ES −0.32 ± 0.26) postmatch compared with 48pre. Cortisol displayed a clear pattern of response with substantial elevations up to 24post compared with Pre and 48pre.

Conclusion:

CMJ1 Flight time:Contraction time appears to be the most useful variable for monitoring neuromuscular status in elite ARF players due to its substantial change compared with 48pre and prematch. Monitoring cortisol, due to its predictable pattern of response, may provide a useful measure of hormonal status.

Restricted access

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.

Restricted access

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.

Restricted access

Benita J. Lalor, Shona L. Halson, Jacqueline Tran, Justin G. Kemp, and Stuart J. Cormack

Purpose: To assess the impact of match-start time and days relative to match compared with the habitual sleep characteristics of elite Australian Football (AF) players. Methods: 45 elite male AF players were assessed during the preseason (habitual) and across 4 home matches during the season. Players wore an activity monitor the night before (−1), night of (0), 1 night after (+1), and 2 nights (+2) after each match and completed a self-reported rating of sleep quality. A 2-way ANOVA with Tukey post hoc was used to determine differences in sleep characteristics between match-start times and days relative to the match. Two-way nested ANOVA was conducted to examine differences between competition and habitual phases. Effect size ± 90% confidence interval (ES ± 90% CI) was calculated to quantify the magnitude of pairwise differences. Results: Differences observed in sleep-onset latency (ES = 0.11 ± 0.16), sleep rating (ES = 0.08 ± 0.14), and sleep duration (ES = 0.08 ± 0.01) between competition and habitual periods were trivial. Sleep efficiency was almost certainly higher during competition than habitual, but this was not reflected in the subjective rating of sleep quality. Conclusions: Elite AF competition does not cause substantial disruption to sleep characteristics compared with habitual sleep. While match-start time has some impact on sleep variables, it appears that the match itself is more of a disruption than the start time. Subjective ratings of sleep from well-being questionnaires appear limited in their ability to accurately provide an indication of sleep quality.

Restricted access

Benita J. Lalor, Jacqueline Tran, Shona L. Halson, Justin G. Kemp, and Stuart J. Cormack

Purpose: To determine the impact of the quality and quantity of sleep during an international flight on subsequent objective sleep characteristics, training and match-day load, self-reported well-being, and perceptions of jet lag of elite female cricketers during an International Cricket Council Women’s T20 World Cup. Methods: In-flight and tournament objective sleep characteristics of 11 elite female cricketers were assessed using activity monitors. Seated in business class, players traveled west from Melbourne, Australia, to Chennai, India. The outbound flight departed Melbourne at 3:30 AM with a stopover in Dubai for 2 hours. The arrival time in Chennai was 8:10 PM local time (1:40 AM in Melbourne). The total travel time was 19 hours 35 minutes. Perceptual ratings of jet lag, well-being, and training and competition load were collected. To determine the impact of in-flight sleep on tournament measures, a median split was used to create subsamples based on (1) in-flight sleep quantity and (2) in-flight sleep quality (2 groups: higher vs lower). Spearman correlation coefficients were calculated to assess the bivariate associations between sleep measures, self-reported well-being, perceptual measures of jet lag, and internal training and match-day load. Results: Mean duration and efficiency of in-flight sleep bouts were 4.72 hours and 87.45%, respectively. Aggregated in-flight sleep duration was 14.64 + 3.56 hours. Players with higher in-flight sleep efficiency reported higher ratings for fatigue (ie, lower perceived fatigue) during the tournament period. Tournament sleep duration was longer, and bed and wake times were earlier compared with habitual. Compared with other nights during the tournament, sleep duration was shorter following matches. Conclusions: Maximizing in-flight sleep quality and quantity appears to have implications for recovery and sleep exhibited during competition. Sleep duration was longer than habitual except for the night of a match, which suggests that T20 matches may disrupt sleep duration.

Restricted access

Benita J. Lalor, Shona L. Halson, Jacqueline Tran, Justin G. Kemp, and Stuart J. Cormack

Purpose: To assess relationships between objective sleep characteristics, external training loads, and subjective ratings of well-being in elite Australian football (AF) players. Methods: A total of 38 elite male AF players recorded objective sleep characteristics over a 15-day period using an activity monitor. External load was assessed during main field sessions, and ratings of well-being were provided each morning. Canonical correlation analysis was used to create canonical dimensions for each variable set (sleep, well-being, and external load). Relationships between dimensions representing sleep, external load, and well-being were quantified using Pearson r. Results: Canonical correlations were moderate between pretraining sleep and external training load (r = .32–.49), pretraining sleep and well-being (r = .32), and well-being and posttraining sleep (r = .36). Moderate to strong correlations were observed between dimensions representing external training load and posttraining sleep (r = .31–.67), and well-being and external training load (r = .32–.67). Player load and Player load 2D (PL2D) showed the greatest association to pretraining and posttraining objective sleep characteristics and well-being. Fragmented sleep was associated with players completing the following training with a higher PL2D. Conclusions: Maximum speed, player load, and PL2D were the common associations between objective sleep characteristics and well-being in AF players. Improving pretraining sleep quality and quantity may have a positive impact on AF players’ well-being and movement strategy during field sessions. Following training sessions that have high maximum speed and PL2D, the increased requirement for sleep should be considered by ensuring that subsequent sessions do not start earlier than required.

Restricted access

Stuart J. Cormack, Renee L. Smith, Mitchell M. Mooney, Warren B. Young, and Brendan J. O’Brien

Purpose:

To determine differences in load/min (AU) between standards of netball match play.

Methods:

Load/min (AU) representing accumulated accelerations measured by triaxial accelerometers was recorded during matches of 2 higher- and 2 lower-standard teams (N = 32 players). Differences in load/min (AU) were compared within and between standards for playing position and periods of play. Differences were considered meaningful if there was >75% likelihood of exceeding a small (0.2) effect size.

Results:

Mean (± SD) full-match load/min (AU) for the higher and lower standards were 9.96 ± 2.50 and 6.88 ± 1.88, respectively (100% likely lower). The higher standard had greater (mean 97% likely) load/min (AU) values in each position. The difference between 1st and 2nd halves’ load/min (AU) was unclear at the higher standard, while lower-grade centers had a lower (−7.7% ± 10.8%, 81% likely) load/min (AU) in the 2nd half and in all quarters compared with the 1st. There was little intrastandard variation in individual vector contributions to load/min (AU); however, higher-standard players accumulated a greater proportion of the total in the vertical plane (mean 93% likely).

Conclusions:

Higher-standard players produced greater load/min (AU) than their lower-standard counterparts in all positions. Playing standard influenced the pattern of load/min (AU) accumulation across a match, and individual vector analysis suggests that different-standard players have dissimilar movement characteristics. Load/min (AU) appears to be a useful method for assessing activity profile in netball.

Restricted access

Amber E. Rowell, Robert J. Aughey, Will G. Hopkins, Andrew M. Stewart, and Stuart J. Cormack

Objective measures of recovery from football match play could be useful for assessing athletes’ readiness to train, if sensitive to preceding match load.

Purpose:

To identify the sensitivity of countermovement-jump (CMJ) performance and concentration of salivary testosterone and cortisol relative to elite football match load.

Methods:

CMJ performance and salivary hormones were measured in 18 elite football players before (27, 1 h) and after (0.5, 18, 42, 66, 90 h) 3 consecutive matches. Match load was determined via accelerometer-derived PlayerLoad and divided into tertiles. Sensitivity of CMJ performance and hormone concentrations to match load was quantified with t statistics and magnitude-based inferences (change in mean as % ± 90% confidence interval) derived with a linear mixed model.

Results:

Jump height was reduced in medium and high load at 0.5 h (10% ± 7% and 16% ± 8%) and 18 h (7% ± 4% and 9% ± 5%) postmatch. There was a 12% ± 7% reduction in ratio of flight time to contraction time (FT:CT) in high load at 0.5 h post, with reductions in medium and high load at 18 h. Reductions in FT:CT persisted at later postmatch time points than changes in jump height. Increased cortisol (range 55–165%) and testosterone (range 17–20%) were observed in all match loads at 0.5 h post, with individual variability thereafter.

Conclusions:

Measures of CMJ performance and hormonal concentrations were sensitive to levels of A League football match load. Although jump height was reduced immediately postmatch, FT:CT provided a more sensitive measure of recovery. Football match play induces an acute hormonal response with substantial individual variability thereafter.