Publications by authors named "Rich Johnston"

Psychostimulants can be employed as a countermeasure to cognitive declines resulting from insufficient sleep. Although caffeine is the most consumed psychostimulant, consumption can cause adverse side-effects, including sleep disturbance. Therefore, there is interest in identifying alternative supplements that improve cognitive performance without compromising subsequent sleep.

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Objectives: Identify tackle characteristics associated with concussions in male professional rugby league.

Design: Case-control study.

Methods: Tackles resulting in 196 clinically diagnosed concussions and 6592 non-concussive tackles were analysed, from the men's rugby league Super League between 2018 and 2022.

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Aims: To test the efficacy of time-restricted eating (TRE) in comparison to dietitian-led individualised dietary guidance to improve HbA1c in people with Type 2 diabetes mellitus.

Methods: In a parallel groups design, 51 adults (35-65 y) with Type 2 diabetes mellitus and overweight/obesity (HbA1c ≥6.5% (48 mmol/mol), BMI ≥25-≤40 kg/m) commenced a six-month intervention.

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Article Synopsis
  • The study wanted to see how different amounts of caffeine affect sleep when taken in the morning, afternoon, or evening.
  • They tested two doses of caffeine (100mg and 400mg) against a placebo with 23 men over several conditions.
  • Results showed that 100mg didn’t affect sleep much, but 400mg could make it harder to fall asleep and negatively change sleep quality if taken close to bedtime.
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Unlabelled: Recognising and removing players with suspected sport-related concussions is crucial for community sports.

Objectives: Quantify rates and factors associated with non-reporting of concussion symptoms in community rugby league.

Methods: Overall, 484 community rugby league players aged ≥18 years and 965 parents of rugby league players aged <18 years completed an online survey, regarding concussion history, knowledge, prevalence and reasons for non-reporting of concussion, long-term implications and perceptions of concussion.

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Purpose: To determine whether menstrual-cycle symptoms are associated with sleep in elite female athletes.

Methods: Sleep was assessed for a minimum of 25 nights (range = 25-31) using activity monitoring and sleep diaries. Menstrual-cycle symptoms were collected over the same duration in 12 elite female professional soccer players.

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Objectives: (1) Determine the validity of instantaneous speed and acceleration and (2) the variation in validity over time (multiple sessions) for global navigation satellite systems (GNSS) devices.

Design: Repeated measures.

Methods: 10-Hz GNSS devices from Statsports (n = 2, Apex Pro) and Catapult (n = 2, Vector S7) were examined, whilst a speed laser manufactured by MuscleLab (n = 1, LaserSpeed) was the criterion measure, sampling at 2.

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Weakley, J, Johnston, RD, Cowley, N, Wood, T, Ramirez-Lopez, C, McMahon, E, and García-Ramos, A. The effects and reproducibility of 10, 20, and 30% velocity loss thresholds on acute and short-term fatigue and recovery responses. J Strength Cond Res 38(3): 465-473, 2024-This study aimed to establish the effects and reproducibility of implementing 10, 20, and 30% velocity loss thresholds (VLTs) during the free-weight barbell back squat on acute and short-term perceived soreness, neuromuscular fatigue, and physical performance.

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The aim was to use a combination of video analysis and microtechnology (10 Hz global positioning system [GPS]) to quantify and compare the speed and acceleration of ball-carriers and tacklers during the pre-contact phase (contact - 0.5s) of the tackle event during rugby league match-play. Data were collected from 44 professional male rugby league players from two Super League clubs across two competitive matches.

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Horsley, BJ, Tofari, PJ, Halson, SL, Kemp, JG, Chalkley, D, Cole, MH, Johnston, RD, and Cormack, SJ. Validity and reliability of thoracic-mounted inertial measurement units to derive gait characteristics during running. J Strength Cond Res 38(2): 274-282, 2024-Inertial measurement units (IMUs) attached to the tibia or lumbar spine can be used to analyze running gait but, with team-sports, are often contained in global navigation satellite system (GNSS) units worn on the thoracic spine.

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Horsley, BJ, Tofari, PJ, Halson, SL, Kemp, JG, Johnston, RD, and Cormack, SJ. Thoracic-worn accelerometers detect fatigue-related changes in vertical stiffness during sprinting. J Strength Cond Res 38(2): 283-289, 2024-Thoracic-mounted accelerometers are valid and reliable for analyzing gait characteristics and may provide the opportunity to assess running-related neuromuscular fatigue (NMF) during training and competition without the need for additional tests, such as a countermovement jump (CMJ).

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Objectives: Quantify and identify factors associated with concussion underreporting in Super League rugby league players.

Design: Cross sectional survey.

Methods: During the 2022 season preseason, 422 Men's and Women's Super League players completed an online survey quantifying player demographics, rugby playing history, concussion history, prevalence of, and reasons for underreporting concussion, concussion knowledge and long-term implications and perceptions of concussion.

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Objectives: To quantify the incidence of concussion and compare between playing levels in male rugby league.

Design: Retrospective cohort.

Methods: Between 2016 and 2022, medically diagnosed concussions in Super League, Championship, and Academy competitions were reported to the Rugby Football League via club medical staff.

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Background: There is an increased risk of subsequent concussion and musculoskeletal injury upon return to play following a sports-related concussion. Whilst there are numerous assessments available for clinicians for diagnosis and during return to play following concussion, many may lack the ability to detect these subclinical changes in function. Currently, there is no consensus or collated sources on the reliability, validity and feasibility of these assessments, which makes it difficult for clinicians and practitioners to select the most appropriate assessment for their needs.

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Background: Regular exercise performed during pregnancy has been shown to reduce the risk of developing perinatal gestational hypertensive conditions. Further evidence on the exact parameters of exercise needed to explain these beneficial responses is required, within both uncomplicated and at-risk pregnancies.

Objective: The aim of this systematic review and meta-analysis was to investigate the effects of aerobic and resistance exercise on blood pressure during pregnancy.

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The obesity pandemic currently affects more than 70 million Americans and more than 650 million individuals worldwide. In addition to increasing susceptibility to pathogenic infections (eg, SARS-CoV-2), obesity promotes the development of many cancer subtypes and increases mortality rates in most cases. We and others have demonstrated that, in the context of B-cell acute lymphoblastic leukemia (B-ALL), adipocytes promote multidrug chemoresistance.

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Background: With the increasing professionalisation of youth sports, training load monitoring is increasingly common in adolescent athletes. However, the research examining the relationship between training load and changes in physical qualities, injury, or illness in adolescent athletes is yet to be synthesised in a systematic review.

Objective: The aim of this review was to systematically examine the research assessing internal and external methods of monitoring training load and physical qualities, injury, or illness in adolescent athletes.

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This longitudinal study modeled children's complex executive function (EF) development using the Groton Maze Learning Task (GMLT). Using a cohort-sequential design, 147 children (61 males, 5.5-11 years) were recruited from six multicultural primary schools in Melbourne and Perth, Australia.

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Weakley, J, McCosker, C, Chalkley, D, Johnston, R, Munteanu, G, and Morrison, M. Comparison of sprint timing methods on performance, and displacement and velocity at timing initiation. J Strength Cond Res 37(1): 234-238, 2023-Sprint testing is commonly used to assess speed and acceleration in athletes.

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The importance of contributors that can result in negative player outcomes in sport and the feasibility and barriers to modifying these to optimise player health and well-being have yet to be established. Within rugby codes (rugby league, rugby union and rugby sevens), within male and female cohorts across playing levels (full-time senior, part-time senior, age grade), this project aims to develop a consensus on contributors to negative biopsychosocial outcomes in rugby players (known as the CoNBO study) and establish stakeholder perceived importance of the identified contributors and barriers to their management. This project will consist of three parts; part 1: a systematic review, part 2: a three-round expert Delphi study and part 3: stakeholder rating of feasibility and barriers to management.

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Article Synopsis
  • This study evaluated the accuracy and reliability of the Perch system for measuring barbell velocity during exercises like squats and bench presses, comparing its results to a 3D motion capture system.
  • Sixteen participants performed exercises at varying weights, and results indicated strong agreement between the Perch and the criterion device, especially for mean velocity, though the Perch slightly underestimated peak velocity.
  • Overall, the Perch showed consistent performance across testing days, suggesting its effectiveness for monitoring athlete performance over time.
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Background: Many elite athletes have suboptimal sleep duration and efficiency, potentially due to factors that may impact sleep onset and offset times. Variability in sleep onset and offset may negatively influence sleep. The sleep regularity index (SRI) is a novel metric for sleep regularity, however there are no published descriptions of SRI in elite athletes.

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Fragile X–associated tremor/ataxia syndrome (FXTAS) is a debilitating late-onset neurodegenerative disease in premutation carriers of the expanded CGG repeat in FMR1 that presents with a spectrum of neurological manifestations, such as gait ataxia, intention tremor, and parkinsonism [P. J. Hagerman, R.

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Objectives: (1) Determine the inter-device and inter-manufacturer reliability; and (2) investigate the variation in reliability over time for common global navigation satellite systems.

Design: Repeated measures.

Methods: A total of twenty 10-Hz devices manufactured by StatSports (n = 10, Apex Pro; StatSports, Newry, Ireland) and Catapult Sports (n = 10, Vector S7; Catapult Sports, Melbourne, Australia) were towed on a sprint sled during 8 × 40-minute team sport movement protocol over a 4-week period.

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Article Synopsis
  • The study aimed to assess sleep quality among elite athletes using the Pittsburgh Sleep Quality Index (PSQI), providing normative data and comparing results across sex and sports.
  • Out of 479 athletes surveyed, 52% had high PSQI scores, indicating poor sleep quality, with team sport athletes experiencing longer wait times to fall asleep but overall longer sleep length.
  • Findings suggest that individual PSQI components, particularly sleep onset latency and perceived sleep quality, significantly impact overall scores, highlighting the need for regular assessments due to variability in sleep quality over time.
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