Showing papers by "John B. Cronin published in 2019"
TL;DR: Despite relatively few studies meeting the inclusion criteria, this review provides practitioners with insight into which isometric training variables to manipulate to achieve desired morphological and neuromuscular adaptations.
Abstract: Isometric training is used in the rehabilitation and physical preparation of athletes, special populations, and the general public. However, little consensus exists regarding training guidelines for a variety of desired outcomes. Understanding the adaptive response to specific loading parameters would be of benefit to practitioners. The objective of this systematic review, therefore, was to detail the medium- to long-term adaptations of different types of isometric training on morphological, neurological, and performance variables. Exploration of the relevant subject matter was performed through MEDLINE, PubMed, SPORTDiscus, and CINAHL databases. English, full-text, peer-reviewed journal articles and unpublished doctoral dissertations investigating medium- to long-term (≥3 weeks) adaptations to isometric training in humans were identified. These studies were evaluated further for methodological quality. Twenty-six research outputs were reviewed. Isometric training at longer muscle lengths (0.86%-1.69%/week, ES = 0.03-0.09/week) produced greater muscular hypertrophy when compared to equal volumes of shorter muscle length training (0.08%-0.83%/week, ES = -0.003 to 0.07/week). Ballistic intent resulted in greater neuromuscular activation (1.04%-10.5%/week, ES = 0.02-0.31/week vs 1.64%-5.53%/week, ES = 0.03-0.20/week) and rapid force production (1.2%-13.4%/week, ES = 0.05-0.61/week vs 1.01%-8.13%/week, ES = 0.06-0.22/week). Substantial improvements in muscular hypertrophy and maximal force production were reported regardless of training intensity. High-intensity (≥70%) contractions are required for improving tendon structure and function. Additionally, long muscle length training results in greater transference to dynamic performance. Despite relatively few studies meeting the inclusion criteria, this review provides practitioners with insight into which isometric training variables (eg, joint angle, intensity, intent) to manipulate to achieve desired morphological and neuromuscular adaptations.
83 citations
TL;DR: The majority of radar-derived kinematic and kinetic descriptors of short sprint performance had acceptable intra-day and inter-day reliability, but split times over the initial 10 m and some variables that include a horizontal force component had only moderate relative reliability.
Abstract: Radar technology can be used to perform horizontal force–velocity–power profiling during sprint-running. The aim of this study was to determine the reliability of radar-derived profiling results fr...
46 citations
TL;DR: Seventeen elite fast bowlers in a training setting were used to train and/or validate five machine learning models by bowling and performing fielding drills, and accuracy was maintained across all models and sampling frequencies.
Abstract: Fast bowlers are at a high risk of overuse injuries. There are specific bowling frequency ranges known to have negative or protective effects on fast bowlers. Inertial measurement units (IMUs) can ...
27 citations
26 citations
20 May 2019
TL;DR: The Vdec method can be reliably used to prescribe sled-pulling loads in young athletes, but practitioners should be aware that the load required to cause a given Vdec is highly individualized.
Abstract: The purpose of this study was to examine the usefulness of individual load–velocity profiles and the between-athlete variation using the decrement in maximal velocity (Vdec) approach to prescribe training loads in resisted sled pulling in young athletes. Seventy high school, team sport, male athletes (age 16.7 ± 0.8 years) were recruited for the study. All participants performed one un-resisted and four resisted sled-pull sprints with incremental resistance of 20% BM. Maximal velocity was measured with a radar gun during each sprint and the load–velocity relationship established for each participant. A subset of 15 participants was used to examine the reliability of sled pulling on three separate occasions. For all individual participants, the load–velocity relationship was highly linear (r > 0.95). The slope of the load–velocity relationship was found to be reliable (coefficient of variation (CV) = 3.1%), with the loads that caused a decrement in velocity of 10, 25, 50, and 75% also found to be reliable (CVs = <5%). However, there was a large between-participant variation (95% confidence intervals (CIs)) in the load that caused a given Vdec, with loads of 14–21% body mass (% BM) causing a Vdec of 10%, 36–53% BM causing a Vdec of 25%, 71–107% BM causing a Vdec of 50%, and 107–160% BM causing a Vdec of 75%. The Vdec method can be reliably used to prescribe sled-pulling loads in young athletes, but practitioners should be aware that the load required to cause a given Vdec is highly individualized.
24 citations
TL;DR: In this paper, a Strength & Conditioning Journal ahead of print available at http://dx.doi.org/10.1519/SSC.0000000000000404 is published.
Abstract: Article published in Strength & Conditioning Journal ahead of print available at http://dx.doi.org/10.1519/SSC.0000000000000404
22 citations
TL;DR: The use of Wearable Resistance (WR) and its place in the conditions of the training period are discussed.
Abstract: THERE ARE MANY TRAINING TOOLS AVAILABLE TO THE COACH FOR THE IMPROVEMENT OF SPEED AND AGILITY. THIS ARTICLE DISCUSSES THE USE OF WEARABLE RESISTANCE (WR) AND ITS PLACE IN THE CONDITIONING CONTINUUM. IN TERMS OF SPECIFIC STRENGTH TRAINING AND TRANSFERENCE OF ADAPTATION TO SPEED AND AGILITY, W
19 citations
TL;DR: A clear understanding of the validity and reliability of different inertial sensors for the analysis of sprinting has yet to be established and future research into the sensor's placement, attachment method and sampling frequency are among several factors that need further investigation.
18 citations
17 citations
TL;DR: WR forearm loading provides a movement specific overload of the arms which significantly alters step kinematics and sprint times ≥10m.
13 citations
TL;DR: V Vest loads (5-40% body mass) were found to significantly increase acute over-ground times (10-50 m 4.1-16.9%, effect sizes [ES] = 0.93-3.11) through significantly decreased velocity, horizontal force, and flight times (2.2% to -17.3%, ES = -0.41 to -3.19).
Abstract: This systematic review aimed to quantify the acute and longitudinal effects that occur with weighted vests during sprint-running. PubMed, SPORTDiscus, and Web of Science were searched using the Boolean phrases (vest OR trunk) AND (sprint*) AND (resist* OR weight OR load*). From 170 articles retrieved, 11 studies (6 acute, 5 longitudinal) met the inclusion criteria. Vest loads (5-40% body mass) were found to significantly increase acute over-ground times (10-50 m 4.1-16.9%, effect sizes [ES] = 0.93-3.11) through significantly decreased velocity (-2.2% to -17.3%, ES = -0.41 to -3.19), horizontal force (-5.9% to -22.1%, ES = -0.85 to -3.30), maximal power (-4.3% to -35.6%, ES = -0.32 to -3.44), and flight times (-8.3% to -14.6%, ES = -0.88 to -1.03), while increasing contact times (14.7-19.6%, ES = 1.80-3.17). Treadmill sprints were less effected until loads >11% body mass were used. Improvements in velocity (1.2-1.3%, ES = 0.24-0.37) and times (10-50 m 1.2-9.4%, ES = 0.25-3.30) were found in longitudinal studies (5.6-18.9% body mass, 3-7 weeks). Future studies should focus on determining the optimum load and volume to clearly establish the training benefits of this form of resisted sprinting.
TL;DR: This review synthesize and critically analyze relevant biological, physiological, and biomechanical research and develop a rationale for the value of EQI training, which offers potential practical applications and highlights future areas of research.
Abstract: Oranchuk, DJ, Storey, AG, Nelson, AR, and Cronin, JB. The scientific basis for eccentric quasi-isometric resistance training: A narrative review. J Strength Cond Res 33(10): 2846-2859, 2019-Eccentric quasi-isometric (EQI) resistance training involves holding a submaximal, yielding isometric contraction until fatigue causes muscle lengthening and then maximally resisting through a range of motion. Practitioners contend that EQI contractions are a powerful tool for the development of several physical qualities important to health and sports performance. In addition, several sports involve regular quasi-isometric contractions for optimal performance. Therefore, the primary objective of this review was to synthesize and critically analyze relevant biological, physiological, and biomechanical research and develop a rationale for the value of EQI training. In addition, this review offers potential practical applications and highlights future areas of research. Although there is a paucity of research investigating EQIs, the literature on responses to traditional contraction types is vast. Based on the relevant literature, EQIs may provide a practical means of increasing total volume, metabolite build-up, and hormonal signaling factors while safely enduring large quantities of mechanical tension with low levels of peak torque. Conversely, EQI contractions likely hold little neuromuscular specificity to high velocity or power movements. Therefore, EQI training seems to be effective for improving musculotendinous morphological and performance variables with low injury risk. Although speculative due to the limited specific literature, available evidence suggests a case for future experimentation.
TL;DR: The use of low- cost 2-dimensional smartphone or tablet video technology integrated with low-cost biomechanical analysis applications could provide valid and reliable access to high levels of data captured outside of a laboratory environment and a more affordable and more readily available solution.
Abstract: JUMPINGAND HOPPING-BASED TESTS CAN PROVIDE VALUABLE INSIGHT INTO AN ATHLETE’S PROFICIENCY IN BALLISTIC SPORTING MOVEMENTS SUCH AS SPRINTING OR CHANGE OF DIRECTION. CAPTURE AND ANALYSIS OF THIS ARE USUALLY EXPENSIVE AND LABORATORY BASED. RECENT ADVANCEMENTS IN INTEGRATED SMARTPHONE VIDEO TECHNOLOGY FROM THE COMMERCIAL SPACE HAVE LED TO AN INCREASE IN THEIR UTILITY FOR SPORTS PERFORMANCE AND COULDBE EXTREMELY USEFUL TO THE STRENGTH AND CONDITIONING COACH, BUT THE ACCURACY AND SENSITIVITY OF THESE ARE LARGELY UNDETERMINED. THIS BRIEF REVIEW DISCUSSES THE ACCURACY OF A SMARTPHONE VIDEO APPLICATION CALLED MY JUMP AND ITS VALIDITY AND RELIABILITY FOR JUMP-BASED DIAGNOSTICS. INTRODUCTION T heuse of various bilateral and unilateral jumpor hop-based tests is common in athletic profiling because they resemble ballistic movements from sports performance such as jumping and sprinting. The proficiency of these movements is paramount for athletic success (3) and has strong correlations as such with tasks including sprint performance (1,6,13,17,20,30) and multidirectional speed (22). Verticaland horizontal-based tests invariably only require the use of a tape measure to record jump distance or height achieved during each trial, or a basic contact mat to measure flight time. However, the potential to capture the kinematic and kinetic characteristics of each trial and describe how an athlete achieves their jump performance, which in the simplest of terms is defined by distance or height achieved, could also be of significant value in determining athletic potential. Capture of such information usually requires the use of expensive laboratorybased equipment such as force platforms (29), motion capture systems (29), pressure sensors (9), or photocell technology (Optogate)Microgate, Bolzano, Italy (23) as well as a high level of training to analyze the output data. The use of 3-dimensional (3-D) video motion analysis is the gold standard for use in assessing quality of jumping and landing tasks. However, the use of low-cost 2-dimensional (2-D) smartphone or tablet video technology integrated with low-cost biomechanical analysis applications could provide valid and reliable access to high levels of data captured outside of a laboratory environment (4,5,12,14,16) and a more affordable and more readily available solution. The current market is flooded with applications such as Jumpster, myVertical, and Vertical Jump Calculator that use the inbuilt accelerometers and gyroscopes within a smartphone. Recent technological advancements in mobile phone video technology, and specifically the availability of high frame rates and screen resolutions in smartphones, have resulted in an exponential increase in their use in sports performance, health, wellness, and in medical cohorts. Applications such as What’s My Vertical, My Jump, and its later release My Jump 2 use this video technology to derive various jump Address correspondence to Anthony P. Sharp, ant.sharp@nzc.nz.
TL;DR: From the results, a difference in rate of development in sprinting performance in girls over 12.7 years compared with younger girls (YG) can be primarily attributed to greater growth rates in YG, contributing to increases in the propulsive impulse during the initial acceleration phase and step length during the maximal speed phase.
Abstract: Article published in Scandinavian Journal of Medicine and Science in Sports on 29 January 2019 (online), available at: https://doi.org/10.1111/sms.13397.
TL;DR: Kinematics and kinetics within each phase are co-dependent within and across each phase; therefore, coaches should consider the biomechanics of an athlete through preceding phases when seeking biomechanical change within a given phase.
Abstract: The biomechanics of the rotational shot put is used to direct coaching to enhance throwing performance. Maximising shot put distance and velocity at the point of release through increasing momentum is of interest to coaches. This narrative review aimed to examine and summarise the critical kinematic variables within each of the six phases of rotational shot put associated with performance and release velocity. Databases were searched using 'shot put', 'biomechanics' and 'track and field throwing', from which 20 articles based on the inclusion criteria were reviewed. The results indicate that the magnitude of transverse thrower-shot angular momentum and thrower-shots path of translation are crucial to performance. In achieving high angular momentum, sweep leg and arm actions need to be well-timed, and their timings and movement likely determine key biomechanical events such as hip to shoulder separations. Generating high release velocities stems from the development and transference of momentum through each phase. Kinematics and kinetics within each phase are co-dependent within and across each phase; therefore, coaches should consider the biomechanics of an athlete through preceding phases when seeking biomechanical change within a given phase. Further research and consideration of kinetics and energy transfer would add value to kinematic observations.
TL;DR: Isometric peak force and late-stage isometric RFD and impulse measurements were found to have low intersession variability regardless of joint angle, however, practitioners need to exercise caution when making inferences about early-stage RFd and impulse measures due to moderate-large variability.
Abstract: Oranchuk, DJ, Storey, AG, Nelson, AR, Neville, JG, and Cronin, JB. Variability of multiangle isometric force-time characteristics in trained men. J Strength Cond Res XX(X): 000–000, 2019—Measurements of isometric force, rate of force development (RFD), and impulse are widely reported. Howeve
TL;DR: Block starts enable athletes to produce a greater amount of net anterior-posterior impulse during early accelerated sprinting, resulting in faster times up to 10 m, and practitioners may wish to train athletes from a block start to improve horizontal force production.
Abstract: This study aimed to understand the kinematic and kinetic differences between two sprint starts: block and split-stance standing. Fourteen sub-elite male sprinters (100 m time: 11.40 ± 0.39 s) perfo...
TL;DR: Article published in Strength & Conditioning Journal available at https://doi.org/10.1519/SSC.0000000000000459
Abstract: Article published in Strength & Conditioning Journal available at https://doi.org/10.1519/SSC.0000000000000459
TL;DR: Wearable resistance enables a player to perform golf shots in an overloaded manner resulting in significant improvements in club head speed and ground reaction forces, and future research is required to assess the long-term adaptations to this form of loading on golf swing performance.
Abstract: Golf is a skill-based sport which requires optimal swing mechanics to improve golf performance. As practitioners seek training methods to improve swing kinetics without compromising swing kinematic...
TL;DR: Youth sprinting performance can be tested reliably on a non-motorised treadmill, especially if the per cent change in the mean and CV are deemed the important reliability measures.
Abstract: The purpose of this study was to quantify the reliability of kinematic and kinetic variables using a sample of pre-peak-height-velocity (PHV) male athletes sprinting on a non-motorised treadmill. F...