Rhodri Lloyd

Cardiff Metropolitan University | cardiffmet · Cardiff School of Sport and Health Sciences

THE DEVELOPMENT OF PHYSICAL FITNESS IN YOUNG ATHLETES IS A RAPIDLY EXPANDING FIELD OF INTEREST FOR STRENGTH AND CONDITIONING COACHES, PHYSICAL EDUCATORS, SPORTS COACHES, AND PARENTS. PREVIOUS LONG-TERM ATHLETE DEVELOPMENT MODELS HAVE CLASSIFIED YOUTH-BASED TRAINING METHODOLOGIES IN RELATION TO CHRONOLOGIC AGE GROUPS, AN APPROACH THAT HAS DISTINCT L...

The current manuscript is a translation of the Position statement on youth resistance training: the 2014 International Consensus. The original manuscript was adapted from the oficial position statement of the UK Strength and Conditioning Association on youth resistance training. It was subsequently reviewed and endorsed by leading professional orga...

The purpose of this study was to compare the effectiveness of 6-week training interventions utilizing different modes of resistance (traditional strength, plyometric and combined training) on sprinting and jumping performance in boys pre- and post-peak height velocity (PHV). Eighty school-age boys were categorized into two maturity groups (pre- or...

Fatigue is known to influence dynamic knee joint stability from a neuromuscular perspective, and electromechanical delay (EMD) plays an important role as the feedback activation mechanism that stabilizes the joint. The aim of this study was to investigate the influence of soccer-specific fatigue on EMD in U13-, U15-, and U17-year-old female soccer...

Purpose: To examine changes to neuromuscular control of leg stiffness following 42 min of soccer-specific exercise. Methods: Ten youth soccer players, aged 15.8 ± 0.4 years, stature 1.73 ± 0.06 m and mass 59.8 ± 9.7 kg, hopped on a force plate at a self-selected frequency before and after simulated soccer exercise performed on a non-motorised tr...

Background Male youth soccer players competing at a high level will typically engage in large volumes of soccer training from a young age. However, it is not known whether the high levels of habitual training that these high-performing players are exposed to limit their ability to respond to strength, plyometric or combined training interventions....

Context: General and local muscular fatigue is postulated to negatively alter lower limb biomechanics; however, few prospective studies have examined the effect of fatigue on tuck jump performance. The tuck jump assessment (TJA) is a criteria-based visual screening tool designed to identify neuromuscular deficits associated with ACL injury. Utiliz...

Kyles, A, Oliver, JL, Cahill, MJ, Lloyd, RS, and Pedley, J. Linear and change of direction repeated sprint ability tests: a systematic review. J Strength Cond Res 37(8): 1703-1717, 2023-The ability to repeatedly sprint is important in many sports, but there is no established protocol for measuring repeated sprint ability (RSA). The purpose of this...

Over the last two decades, the topic of long-term athletic development has grown in popularity within the academic literature and has influenced the structure of talent development pathways for youth athletes across many sports. The premise of long-term athletic development is salient on the habitual development of ‘athleticism’ over time to improv...

Regular participation in well-designed resistance training programmes can offer observable health and fitness benefits to children and adolescents. In addition to increasing muscular strength and power, resistance training can increase bone mineral density, improve cardiovascular risk factors, fuel metabolic health, facilitate weight control, enhan...

Speed and agility are fundamental locomotive skills that form the basis of many physical activities and are known to contribute to success in youth sport. Speed and agility represent unique qualities; speed refers to the ability to move quickly in a straight line, whereas agility refers to the ability to rapidly change direction in response to a st...

This book presents an integrated, research-driven, collection of 54 evidence-based chapters. Chapters are founded on the research and practical experience of 104 internationally renowned scientists and clinicians, from 25 countries. Each extensively referenced chapter concludes with a bulleted summary and where appropriate is cross-referenced to co...

PURPOSE: The Tuck Jump Assessment (TJA) is traditionally used as a subjective screening method to visually assess for neuromuscular deficits associated with lower extremity injury. More recently, bilateral kinetics during the TJA have been reported (Kember et al., 2022). While the magnitude of interlimb asymmetries is task-specific and has been exp...

INTRODUCTION: Muscular strength and plyometric ability develop naturally in youth through growth and maturation. Resistance and plyometric training have also shown a synergistic effect with natural growth processes to produce augmented performance throughout maturation. However, little is known of the natural changes in kinetic mechanisms that supp...

Neurovascular coupling (NVC) is mediated via nitric oxide signalling, which is independently influenced by sex hormones and exercise training. Whether exercise training differentially modifies NVC pre- vs. post-puberty, where levels of circulating sex hormones will differ greatly within- and between-sexes, remains to be determined. Therefore, we in...

full abstract 12 healthy females Age 22.0 ± 4.6 yrs; height 1.69 ± 0.07 m; body mass 69.3 ± 10.3 kg. METHODOLOGY RESULTS CONCLUSIONS PURPOSE APPLICATIONS Table 1. Interlimb kinetics and asymmetries during different phases of the TJA Variable C1 C2 p % Change Effect Size (g) Mean ± SD Mean asymmetry (%) Mean ± SD Mean asymmetry (%)

PURPOSE: Evaluating landing kinetics during the tuck jump assessment (TJA) is critical to determine adequate stabilization needed to assess movement quality and deficits. Interlimb kinematic asymmetries are a critical component of the TJA quality criterion, but it remains unclear if kinetic asymmetries, which are considered a potential threshold fo...

The aim of the study was to examine the birth quartile and maturity status distributions of male academy cricketers. Participants included two hundred and thirteen junior cricket players, aged between 9 and 18 years. Players were separated into birth quartiles, and also grouped as early, average, or late maturers. For the whole cohort, there was a...

The aim of this study was to examine the effects of maturity status on drop jump (DJ) kinetics in young male athletes (categorised as early-pre [<-2.51 years], late-pre [-1.99 to-1.00 years], circa [-0.50 to 0.50 years] and post-PHV [>1.00 years]). All athletes performed a DJ from a 30 cm box onto force plates with performance variables (jump heigh...

Abstract Background Among youth, plyometric-jump training (PJT) may provide a safe, accessible, and time-efficient training method. Less is known on PJT effectiveness according to the maturity status. Objective This systematic review with meta-analysis set out to analyse the body of peer-reviewed articles assessing the effects of PJT on measures of...

The aim of this review was to describe and summarize the scientific literature on programming parameters related to jump or plyometric training in male and female soccer players of different ages and fitness levels. A literature search was conducted in the electronic databases PubMed, Web of Science and Scopus using keywords related to the main top...

Gymnastics has a history of high injury incidence rates. However, little is known about the injury pathology in young gymnasts. The purpose of this study was to fill gaps in the literature by providing insight into the injury pathology in gymnasts aged 6 to 17 years. This study was retrospective in design, where injury data were collected using a Q...

While the existing literature reports strong associations between measures of physical fitness and indices of golf swing performance, such as club head speed (CHS), there is limited evidence to support this observation in youth golfers.

Physical education (PE) teachers and strength and conditioning (S&C) coaches are well placed to develop motor competence within youth populations. However, both groups’ perceptions of important motor competencies are relatively unknown, especially when considering stage of maturity. Therefore, this study aimed to 1) present PE teachers and S&C coac...

Background: Young athletes who specialize early in a single sport may subsequently be at increased risk of injury. While heightened injury risk has been theorized to be related to volume or length of exposure to a single sport, the development of unhealthy, homogenous movement patterns, and rigid neuromuscular control strategies may also be indict...

Radnor, JM, Oliver, JL, Waugh, CM, Myer, GD, and Lloyd, RS. Muscle Architecture and Maturation Influence Sprint and Jump Ability in Young Boys: A Multistudy Approach. J Strength Cond Res 36(10): 10.1519/JSC.0000000000003941-This series of experiments examined the influence of medial gastrocnemius (GM) and vastus lateralis (VL) muscle architecture (...

Apply it! After reading this article, exercise professionals will be able to: • Understand why it is useful to assess strength and power in youth. • Appreciate why it is important to consider maturity and size when assessing the strength and power of youth. • Identify different tests that can be used to assess strength and power in youth, depending...

Introduction: It is important to increase awareness about the effect COVID-19 pandemic restrictions have on children with autism spectrum disorder (ASD) and how these limitations influence the cardiovascular health (CVH) of this vulnerable population. Little is known about how changes caused by the pandemic impact on modifiable risk factors for car...

Barillas, SR, Oliver, JL, Lloyd, RS, and Pedley, J. Kinetic responses to external cues are specific to both the type of cue and type of exercise in adolescent athletes. J Strength Cond Res XX(X): 000-000, 2022-The purpose of this study was to examine how external cues influence kinetics during isometric and dynamic tasks in adolescent athletes. Fif...

INTRODUCTION: Drop jumps (DJ) are effective screening tools for stretch-shortening cycle (SSC) function in youth. During periods of accelerated growth, it has been postulated that youth experience disturbances in neuromuscular control termed "adolescent awkwardness". However, this has predominantly been assessed using fitness performance assessment...

This cross-sectional study investigated how stretch-shortening cycle (SSC) function and kinetic variables differed between young female gymnasts of varying competitive levels. Drop jump (DJ) force-time profiles were examined in 118 female gymnasts, sub-divided by competitive level (n = 21 recreational, n = 41 regional and n = 50 elite). DJ force-ti...

Background Weightlifting training (WLT) is commonly used to improve strength, power and speed in athletes. However, to date, WLT studies have either not compared training effects against those of other training methods, or been limited by small sample sizes, which are issues that can be resolved by pooling studies in a meta-analysis. Therefore, the...

The tuck jump assessment (TJA) is a criteria-based screening tool designed to identify neuromuscular deficits associated with ACL injury [1]. Gaps in research indicate that kinetic analysis of the TJA enhance sensitivity of TJA measures to identify future injury risk [2]. Specifically, neuromuscular fatigue has been considered to cause detrimental...

The aim of this review was to describe and summarize the scientific literature on programming parameters related to jump or plyometric training in male and female soccer players of different age and fitness levels. A literature search was conducted in the electronic databases PubMed, Web of Science and SCOPUS, using keywords related to the main top...

Long-term athletic development practices have been recommended for the past two decades. However, limited research exists exploring the knowledge and skills required by practitioners to optimise long-term athletic development. Therefore, this study aimed to evaluate the knowledge, adherence, practices, and challenges of practitioners responsible fo...

Purpose: This study aimed to evaluate a 10-month neuromuscular training (NMT) intervention on isometric and dynamic kinetics, standing long jump (SLJ) distance, speed and sport-specific performance. Methods: Forty-three pre-pubertal female gymnasts were allocated into either a gymnastics + NMT (gNMT; n = 16), gymnastics only (GYM, n = 15) or mat...

Key points: It has long been hypothesised that cardiovascular adaptation to endurance training is augmented following puberty. We investigated whether differences in cardiac and haematological variables exist, and to what extent, between endurance-trained vs. untrained, pre- and post-peak height velocity (PHV) children, and how these central facto...

This study aimed to: (1) examine differences in physical performance across birth-quartiles and maturity-status, and (2) determine the relationships among relative age, maturation and physical performance in young male soccer players. The sample included 199 males aged between 8.1 and 18.9 years, from two professional soccer academies in the Englis...

Children with autism have poor lifestyle and unhealthy behaviours (Heffernan et al 2019 It is known that Cardiovascular disease (impacts mostly in older cohorts with Autism, but the seeds are sown in early life as poor lifestyle and unhealthy behaviours typically translate into a higher prevalence of CVD in later life (Healy et al 2017) There are m...

This prospective longitudinal trial aimed to 1) determine the role of head impact exposure on behavioral/cognitive outcomes, and 2) assess the protective effect(s) of a jugular vein compression (JVC) collar on behavioral/cognitive outcomes following one season of high-school football. Participants included 284 male high-school football players aged...

In the sport of golf, club head speed has been associated with higher skill levels in golfers and lower overall scoring. Research has shown that club head speed is an important measure of golf swing performance that can be enhanced with appropriate strength and conditioning interventions. Understanding the determinants of club head speed can help i...

This study aims to determine whether motor coordination influences the perception-decision time (perceptual-cognitive factor) and movement response time (physical factor) of young soccer players in a sport-specific agility task regardless of maturation. Eighty-seven young male soccer players were analysed. Anthropometric measurements were used to d...

Leading health organizations and long- term athletic development models have identified the need to develop movement competencies in children and adolescents. The athletic motor skill competencies (AMSCs) have been identified as key skills that form the foundations of all athletic movements. The AMSCs form an integral part of the long-term athletic...

Background Youth populations benefit from neuromuscular training; however, the extent to which training frequency, baseline fitness, and maturity status moderate the response to long-term neuromuscular training in male youth remains unclear. Hypothesis Twice-weekly training (G2x) would induce larger improvements in movement competency and strength...

The aims of the current study were to i) investigate differences in maximal rebound jump kinetics in boys at different stages of maturity, and ii) determine the relationship of muscle architecture characteristics to maximal rebound jump kinetics. One hundred twenty-seven male, secondary school children were categorised into maturity groups (pre-, c...

Early sport specialization involves physically immature children participating in intensive year-round training and/or competition for a single sport. The lack of sport exposure and diversification during the developmental years may underlie the increased risk of overuse injuries, blunting of motor skill development, psychosocial issues, overtraini...

Cardiovascular (CV) disease is a leading cause of death in the autistic community.They experience higher levels of several independent risk factors of CV mortality (Heffernan et al., 2019). These are exacerbated by a sedentary lifestyle and high levels of anxiety. There is concern that the COVID-19 pandemic may have exacerbated these CV risk factor...

The stretch‐shortening cycle (SSC) assists in effective force attenuation upon landing and augments force generation at take‐off during a drop vertical jump (DVJ). General performance outcomes such as jump height or peak measures have been used to assess SSC function in youth populations; however, these discrete metrics fail to provide insight into...

Low physical fitness is associated with reduced physical activity and increased cardiovascular diseases. To date, limited research has compared physical fitness levels between children with and without autism spectrum disorder (ASD). Therefore, the primary aim was to investigate if differences in fitness levels exist between children with ASD and a...

Verbal cues are tools used by practitioners in developing a youth athlete's motor skill abilities. External cues may optimize athletic performance and movement competencies in adults with trends for youth athletic populations following suit. However, maturation, training age, and cognitive age may interact with the efficacy of cues used. To better...

The purpose of this article is to provide an overview of the growth, maturation and resistance training-related changes in muscle-tendon and neuromuscular mechanisms in youth, and the subsequent effect on performance. Sprinting, jumping, kicking, and throwing are common movements in sport that have been shown to develop naturally with age, with imp...

Lloyd, RS, Howard, SW, Pedley, JS, Read, PJ, Gould, ZI, and Oliver, JL. The acute effects of accentuated eccentric loading on drop jump kinetics in adolescent athletes. J Strength Cond Res 36(9): 2381-2386, 2022-The purpose of the study was to determine the acute effects of accentuated eccentric loading (AEL) on drop jump kinetics in adolescent ath...

The purpose of this study was to investigate the landscape of Fundamental Movement Skills (FMS) and strength development in professional football (soccer) academies in the UK. To achieve this, we interviewed 16 participants, whose primary responsibility was the physical development of youth players from a variety of Elite Player Performance Plan (E...

PurposeTo quantify the effects of an externally worn collar device for mitigating the influence of repetitive head impacts on alterations to diffusion tensor imaging (DTI) metrics of white matter.Methods Fifteen female high-school soccer athletes (age: 14.00–16.98 yrs) completed pre- and post-season DTI over two consecutive years, including measure...

PurposeNeuromuscular training aims to enhance motor skill competency and increase muscle strength. However, the effectiveness of short-duration interventions focused on addressing lower limb injury risk factors in male youth athletes at different stages of maturity remains unknown.Methods Forty-eight young male academy cricket players [pre-peak hei...

Context: Kinetic profiles of athletes performing the tuck jump assessment (TJA) are unknown and may provide insight into the risk of anterior cruciate ligament injury. Design: The purpose of this study was to (1) analyze vertical kinetics of the TJA and (2) determine the stabilization of the kinetics across successive jumping cycles. Methods:...

Despite previous misconceptions, youth participation in weightlifting is now recognized as safe and beneficial when delivered, programed, and monitored by a qualified professional. This article explores teaching progressions to help coaches periodize weightlifting training for young or novice athletes, with consideration to the theoretical concepts...

Synergistic development of muscular strength and motor skill competency is central to long-term athletic development. However, these qualities need to be developed in a logical and progressive manner, and training methods need to be developmentally appropriate, engaging, and enjoyable for young athletes to help them build a positive association wit...

Pedley, JS, Lloyd, RS, Read, PJ, Moore, IS, Myer, GD, and Oliver, JL. A novel method to categorize stretch-shortening cycle performance across maturity in youth soccer players. J Strength Cond Res XX(X): 000-000, 2020-This study used a novel method to categorize stretch-shortening cycle (SSC) function during a drop jump (DJ) using the force-time cu...

Strength and conditioning provision for young athletes offers unique challenges and opportunities for coaches. Periods of rapid and nonuniform growth in skeletal structures can result in temporary reductions in athletic performance and heightened injury risk. Despite the increased risk of injury in young athletes, surprisingly, there is often a lac...

Purpose Jump-landing assessments provide a means to quantify an individual’s ability to attenuate ground reaction forces, generate lower limb explosive power and maintain joint alignment. In order to identify risk factors that can be targeted through appropriate training interventions, it is necessary to establish which (scalar) objective kinetic,...

Leading global physical activity guidelines advocate that young children need to engage in activities that strengthen musculoskeletal tissues and improve movement skill competency. The purpose of this study was to examine the effects of delivering strength and conditioning as part of the physical education curriculum on athletic motor skill compete...

Background The triple hop for distance test commonly uses a limb symmetry index (LSI) ‘pass’ threshold of > 90% for total hop distance following anterior cruciate ligament reconstruction (ACLR). However, understanding the manner in which athletes generate and dissipate forces during consecutive hops within the test may provide greater insight into...

Cahill, MJ, Oliver, JL, Cronin, JB, Clark, K, Cross, MR, Lloyd, RS, and Lee, JE. Influence of resisted sled-pull training on the sprint force-velocity profile of male high-school athletes. J Strength Cond Res XX(X): 000-000, 2020-Although resisted sled towing is a commonly used method of sprint-specific training, little uniformity exists around tra...

PurposeThis cross-sectional study investigated dynamic force–time variables and vaulting performance in young female gymnasts of different maturity status.Methods120 gymnasts aged 5–14 years were sub-divided into maturity groupings using percent of predicted adult height (%PAH) attained. Participants performed three jumping protocols, the squat jum...

An understanding of how movement competency, strength, and power interacts with natural growth and maturation is required in order to determine meaningful changes with developing athletes. Isometric and dynamic testing in youth athletes provide insight into the natural development of the force‐velocity (F‐V) spectrum. Two‐hundred and six young male...

PURPOSE To examine the effects of a 9-month NMT intervention on isometric and dynamic force-time characteristics during strength and power tests and vertical takeoff velocity during gymnastics vaulting. METHODS Forty-three pre-pubertal female gymnasts were subdivided into gymnastics + NMT (GYM+NMT; n = 16), gymnastics only (GYM, n = 15) groups and...

Objectives Examine growth and maturation trends in dynamic balance using the anterior reach Y-Balance test, and its utility as an injury risk screening tool. Design Cross sectional and prospective cohort. Setting Elite male youth soccer players. Participants 346 players grouped as pre, circa or post peak height velocity (PHV). Main outcome meas...

There is a renewed interest is resisted sled training (RST); however, little uniformity exists regarding the integration of best practices in RST for young athletes. This article reviews the prescription of load, methods of RST, and the integration of sprint-specific periodized training blocks during the preparatory phase to elicit the greatest gai...