Objective Measures of Strain and Subjective Muscle Soreness Differ Between Positional Groups and Season Phases in American College Football.

Purpose: To assess objective strain and subjective muscle soreness in "Bigs" (offensive and defensive line), "Combos" (tight ends, quarterbacks, line backers, and running backs), and "Skills" (wide receivers and defensive backs) in American college football players during off-season, fall camp, and in-season phases.

Methods: Twenty-three male players were assessed once weekly (3-wk off-season, 4-wk fall camp, and 3-wk in-season) for hydroperoxides (free oxygen radical test [FORT]), antioxidant capacity (free oxygen radical defense test [FORD]), oxidative stress index (OSI), countermovement-jump flight time, Reactive Strength Index (RSI) modified, and subjective soreness. Linear mixed models analyzed the effect of a 2-within-subject-SD change between predictor and dependent variables.

Uphill sprinting load- and force-velocity profiling: Assessment and potential applications.

This study aimed to quantify the validity and reliability of load-velocity (LV) relationship of hill sprinting using a range of different hill gradients and to describe the effect of hill gradient on sprint performance. Twenty-four collegiate-level athletes performed a series of maximal sprints on either flat terrain or hills of gradients 5.2, 8.

The Association Between Alterations in Redox Homeostasis, Cortisol, and Commonly Used Objective and Subjective Markers of Fatigue in American Collegiate Football.

Purpose: To assess associations between a free oxygen radical test (FORT), free oxygen radical defense test (FORD), oxidative stress index, urinary cortisol, countermovement jump (CMJ), and subjective wellness in American college football.

Methods: Twenty-three male student athlete American college football players were assessed over 10 weeks: off-season conditioning (3 wk), preseason camp (4 wk), and in season (3 wk). Assessments included a once-weekly FORT and FORD blood sample, urinary cortisol sample, CMJ assessment including flight time, reactive strength index modified and concentric impulse, and a daily subjective wellness questionnaire.

The Validity of a Global Navigation Satellite System for Quantifying Small-Area Team-Sport Movements.

Delaney, JA, Wileman, TM, Perry, NJ, Thornton, HR, Moresi, MP, and Duthie, GM. The validity of a global navigation satellite system for quantifying small-area team-sport movements. J Strength Cond Res 33(6): 1463-1466, 2019-The recent development of global navigation satellite systems (GNSS) has improved the availability and signal strength of surrounding satellites compared with traditional global positioning systems, although their ability to quantify rapid changes in speed may still be limited.

Developing Athlete Monitoring Systems in Team Sports: Data Analysis and Visualization.

In professional team sports, the collection and analysis of athlete-monitoring data are common practice, with the aim of assessing fatigue and subsequent adaptation responses, examining performance potential, and minimizing the risk of injury and/or illness. Athlete-monitoring systems should be underpinned by appropriate data analysis and interpretation, to enable the rapid reporting of simple and scientifically valid feedback. Using the correct scientific and statistical approaches can improve the confidence of decisions made from athlete-monitoring data.

Interunit Reliability and Effect of Data-Processing Methods of Global Positioning Systems.

Purpose: To establish the interunit reliability of a range of global positioning system (GPS)-derived movement indicators, to determine the variation between manufacturers, and to investigate the difference between software-derived and raw data.

Methods: A range of movement variables were obtained from 27 GPS units from 3 manufacturers (GPSports EVO, 10 Hz, n = 10; STATSports Apex, 10 Hz, n = 10; and Catapult S5, 10 Hz, n = 7) that measured the same team-sport simulation session while positioned on a sled. The interunit reliability was determined using the coefficient of variation (%) and 90% confidence limits, whereas between-manufacturers comparisons and comparisons of software versus raw processed data were established using standardized effect sizes and 90% confidence limits.

Running Intensities in Elite Youth Soccer by Age and Position.

Duthie, GM, Thornton, HR, Delaney, JA, Connolly, DR, and Serpiello, FR. Running intensities in elite youth soccer by age and position. J Strength Cond Res 32(10): 2918-2924, 2018-The purpose of this investigation was to examine differences between the peak running speed, acceleration, and metabolic power of elite youth soccer across a range of age levels by position.

Relationship Between Physical Performance Testing Results and Peak Running Intensity During Professional Rugby League Match Play.

Duthie, GM, Thornton, HR, Delaney, JA, McMahon, JT, and Benton, DT. Relationship between physical performance testing results and peak running intensity during professional rugby league match play. J Strength Cond Res 34(12): 3506-3513, 2020-The purpose of this study was to examine the relationship between individual athletes' physical characteristics and both the peak running intensities and the decline in peak running intensities during competition.

Effects of Preseason Training on the Sleep Characteristics of Professional Rugby League Players.

Purpose: To investigate the influence of daily and exponentially weighted moving training loads on subsequent nighttime sleep.

Methods: Sleep of 14 professional rugby league athletes competing in the National Rugby League was recorded using wristwatch actigraphy. Physical demands were quantified using GPS technology, including total distance, high-speed distance, acceleration/deceleration load (SumAccDec; AU), and session rating of perceived exertion (AU).

Importance, Reliability, and Usefulness of Acceleration Measures in Team Sports.

Delaney, JA, Cummins, CJ, Thornton, HR, and Duthie, GM. Importance, reliability and usefulness of acceleration measures in team sports. J Strength Cond Res 32(12): 3494-3502, 2018-The ability to accelerate, decelerate, and change direction efficiently is imperative to successful team sports performance.

Duration-specific running intensities of Australian Football match-play.

Objectives: To establish the position and duration-specific running demands of Australian Football (AF) competition for the prescription and monitoring of specific training drills.

Design: An observational time-motion analysis was performed on 40 professional AF players during 30 games throughout the 2014-15 competitive seasons.

Methods: Player movements were collected and peak values were calculated for moving averages of between 1-10min in duration for relative distance (mmin), high-speed relative distance (HSmmin), average acceleration/deceleration (ms) and metabolic power (P).

Peak Running Intensity of International Rugby: Implications for Training Prescription.

Purpose: To quantify the duration and position-specific peak running intensities of international rugby union for the prescription and monitoring of specific training methodologies.

Methods: Global positioning systems (GPS) were used to assess the activity profile of 67 elite-level rugby union players from 2 nations across 33 international matches. A moving-average approach was used to identify the peak relative distance (m/min), average acceleration/deceleration (AveAcc; m/s), and average metabolic power (P) for a range of durations (1-10 min).

Effects of a 2-Week High-Intensity Training Camp on Sleep Activity of Professional Rugby League Athletes.

Purpose: To investigate the effects of a training camp on the sleep characteristics of professional rugby league players compared with a home period.

Methods: During a 7-d home and 13-d camp period, time in bed (TIB), total sleep time (TST), sleep efficiency (SE), and wake after sleep onset were measured using wristwatch actigraphy. Subjective wellness and training loads (TL) were also collected.

Importance of Various Training-Load Measures in Injury Incidence of Professional Rugby League Athletes.

Purpose: To investigate the ability of various internal and external training-load (TL) monitoring measures to predict injury incidence among positional groups in professional rugby league athletes.

Methods: TL and injury data were collected across 3 seasons (2013-2015) from 25 players competing in National Rugby League competition. Daily TL data were included in the analysis, including session rating of perceived exertion (sRPE-TL), total distance (TD), high-speed-running distance (>5 m/s), and high-metabolic-power distance (HPD; >20 W/kg).

The Validity and Contributing Physiological Factors to 30-15 Intermittent Fitness Test Performance in Rugby League.

Scott, TJ, Duthie, GM, Delaney, JA, Sanctuary, CE, Ballard, DA, Hickmans, JA, and Dascombe, BJ. The validity and contributing physiological factors to 30-15 intermittent fitness test performance in rugby league. J Strength Cond Res 31(9): 2409-2416, 2017-This study examined the validity of the 30-15 Intermittent Fitness Test (30-15IFT) within rugby league.

Factors That Influence Running Intensity in Interchange Players in Professional Rugby League.

Background: Rugby league coaches adopt replacement strategies for their interchange players to maximize running intensity; however, it is important to understand the factors that may influence match performance.

Purpose: To assess the independent factors affecting running intensity sustained by interchange players during professional rugby league.

Methods: Global positioning system (GPS) data were collected from all interchanged players (starters and nonstarters) in a professional rugby league squad across 24 matches of a National Rugby League season.

Acceleration-Based Running Intensities of Professional Rugby League Match Play.

Unlabelled: Rugby league involves frequent periods of high-intensity running including acceleration and deceleration efforts, often occurring at low speeds.

Purpose: To quantify the energetic cost of running and acceleration efforts during rugby league competition to aid in prescription and monitoring of training.

Methods: Global positioning system (GPS) data were collected from 37 professional rugby league players across 2 seasons.

Predicting Self-Reported Illness for Professional Team-Sport Athletes.

Purpose: To identify contributing factors to the incidence of illness for professional team-sport athletes, using training load (TL), self-reported illness, and well-being data.

Methods: Thirty-two professional rugby league players (26.0 ± 4.

Validity of Skinfold-Based Measures for Tracking Changes in Body Composition in Professional Rugby League Players.

Unlabelled: High levels of lean mass are important in collision-based sports for the development of strength and power, which may also assist during contact situations. While skinfold-based measures have been shown to be appropriate for cross-sectional assessments of body composition, their utility in tracking changes in lean mass is less clear.

Purpose: To determine the most effective method of quantifying changes in lean mass in rugby league athletes.

Reliability and Usefulness of the 30-15 Intermittent Fitness Test in Rugby League.

This study examined the reliability and usefulness of the 30-15 Intermittent Fitness Test (30-15(IFT)) within rugby league. Fifty-five young rugby league players participated in the study. These included representative players from Under 16s (n = 19; 15.

Establishing Duration-Specific Running Intensities From Match-Play Analysis in Rugby League.

Unlabelled: Rugby league coaches often prescribe training to replicate the demands of competition. The intensities of running drills are often monitored in comparison with absolute match-play measures. Such measures may not be sensitive enough to detect fluctuations in intensity across a match or to differentiate between positions.

Contributing Factors to Change-of-Direction Ability in Professional Rugby League Players.

Rugby league is an intermittent team sport in which players are regularly required to accelerate, decelerate, and change direction rapidly. This study aimed to determine the contributing factors to change-of-direction (COD) ability in professional rugby league players and to validate the physical and physiological components of a previously proposed COD ability predictor model. Thirty-one male professional rugby league players (age: 24.

The validity and reliability of a customized rigid supportive harness during Smith machine back squat exercise.

Although the back squat exercise is commonly prescribed to both athletic and clinical populations, individuals with restricted glenohumeral mobility may be unable to safely support the bar on the upper trapezius using their hands. The aims of this study were to investigate the validity and reliability of a back squat variation using a rigid supportive harness that does not require unrestricted glenohumeral mobility for quantifying 1 repetition maximum (1RM). Thirteen young men (age = 25.