Dr Alex Dinsdale

Dinsdale, AJ and Bissas, A. Eliciting Postactivation Potentiation With Hang Cleans depends on the recovery duration and the individual's 1 repetition maximum strength. J Strength Cond Res XX(X): 000-000, 2019-Acutely coupling biomechanically similar resistance exercises (e.g., back squats) with subsequent explosive movements (e.g., countermovement jumps [CMJs]) can elicit an enhancement in explosive force and power production, which is known as postactivation potentiation (PAP). However, limited information exists with regard to the coupling of hang cleans with the CMJ. The purpose of this study was to determine the effectiveness of the hang clean at eliciting PAP through the systematic appraisal of the implemented recovery interval. Twelve explosively trained male track and field athletes completed 8 randomized protocols. These consisted of a structured warm-up, 3 baseline CMJs performed on a force platform, 3 reps of hang cleans set at 90% of 1 repetition maximum (1RM), a randomized rest, and 3 post-CMJs. The rest intervals were set at 0 (T0), 1 (T1), 2 (T2), 3 (T3), 4 (T4), 5 (T5), and 6 (T6) minutes after completing the hang cleans. A repeated-measures analysis of variance showed that the hang cleans did not elicit PAP, although there were significant (p < 0.05) decreases in jump height (JH) for T0 (-4%), T2 (-3%), and T3 (-3.3%). Interestingly, when splitting the subjects based on absolute 1RM hang clean (above 80 kg = strong and below 80 kg = weak), significant differences (p < 0.05) in JH were observed between the groups at T1 (strong -1.2% and weak +3.8%) and T5 (strong +5.1% and weak -1.9%). Our results suggest that to elicit PAP when using hang-clean protocols, it is important to establish first the function between individual strength levels and recovery duration as this may lead to contrasting optimal performance windows for different explosively trained athletes.

This report provides an analysis of all the finalists' best throw and comprised a 3-dimensional biomechanical analysis of the path and velocity of the implement head throughout the turns and release paramters. Key kinematic variables of the throwing technique are also presented. This is a useful analysis for those interested in hammer throwing performance. The full report is available from the IAAF website https://www.iaaf.org/about-iaaf/documents/research#2017-iaaf-world-championships-biomechanics-st

This report provides an analysis of all the finalists' best throw and comprised a 3-dimensional biomechanical analysis of the path and velocity of the implement head throughout the turns and release paramters. Key kinematic variables of the throwing technique are also presented. This is a useful analysis for those interested in hammer throwing performance. The full report is available from the IAAF website https://www.iaaf.org/about-iaaf/documents/research#2017-iaaf-world-championships-biomechanics-st

This report provides an analysis of all the finalists' best throw and comprised a 3-dimensional biomechanical analysis of the path and velocity of the implement throughout the throw and the release paramters. Key kinematic variables of the throwing technique are also presented. This is a useful analysis for those interested in shot put performance. The full report is available from the IAAF website https://www.iaaf.org/about-iaaf/documents/research#2017-iaaf-world-championships-biomechanics-st

This report provides an analysis of all the finalists' best throw and comprised a 3-dimensional biomechanical analysis of the path and velocity of the implement throughout the throw and the release paramters. Key kinematic variables of the throwing technique are also presented. This is a useful analysis for those interested in shot put performance. The full report is available from the IAAF website https://www.iaaf.org/about-iaaf/documents/research#2017-iaaf-world-championships-biomechanics-st

Introduction: Considering a) that the ‘learning effect’ in isokinetic assessments may impact on a clinician’s ability to detect genuine changes in muscle function and b) the rare nature of constant velocity movements in daily activities, it becomes apparent that familiarisation is key to optimising the reproducibility of measurements. This study examined the impact of testing protocols which differed in repetition number and rest intervals on the stability of isokinetic and isometric measurements conducted on the knee extensors and flexors across multiple testing sessions. Methods: 12 males (age: 23.3 ± 1.6 years; height: 1.80 ± 0.06 m; mass: 83.2 ± 9.6 kg) were randomly divided into a LONG and SHORT group and completed 6 group-specific testing sessions (48-96 hours rest between visits) which involved maximal isokinetic (30o/s, 90o/s, 180o/s) and isometric repetitions (extensors: 70o - flexors: 50o) in seated and prone positions on a Cybex NORM dynamometer. The LONG protocol involved 70 submaximal and 36 maximal repetitions and a total resting time of 3140s whereas the SHORT included 40 submaximal and 24 maximal repetitions with a total resting time of 2360s. A range of statistical techniques including measures of reliability were employed. Results: Overall the LONG group exhibited higher torque values (+10-25%) for extensors and flexors under both isokinetic and isometric conditions. However, a mixed-design ANOVA revealed no main effects for each factor (group, visit) nor any significant interaction. Intraclass Correlation Coefficients (ICCs) for the isokinetics did not show any trend between visits but generally the LONG protocol produced consistently ICCs over 0.90 (mean ICC: LONG = 0.92 vs SHORT = 0.83). LONG group values for Standard error of measurement, Typical error, Limits of agreement and Coefficients of variation were slightly better than SHORT. The LONG protocol produced better reliability for the isometric extensors torque (ICC: 0.93 vs 0.67) but the SHORT for the flexors (ICC: 0.78 vs 0.95). Discussion: A single visit can produce similar results as repeat visits providing a conventional protocol is applied and strict adherence to testing principles (stabilisation, instructions, feedback) is ensured. Two sessions may be adequate to “learn” the movements and reach a satisfactory degree of performance stability. However, a longer protocol comprising an increased number of submaximal-maximal trials (≥ 20 per speed) supplemented by rest intervals of 30-90s (between repetitions-speeds) and 10min between positions, and a prone position for leg flexors can offer additional reliability. Ultimately, the exact level of acceptable reproducibility is always decided by the researcher after considering sample characteristics and type of application.

Training for both sporting and military performance is common practice within army trainee populations, although it is currently unknown what effect this combination of training methods may have on the physical attributes required for overall physical preparedness. This study examined the effects of sport-specific training on general fitness in a professional military population. Four hundred and twenty-three Greek male army cadets completed a 12-week training regimen involving standard physical training (callisthenics, strength and endurance running exercises) and either general military training (GMT) or sport military training (SMT). A series of physical tests took place before and after the training period: a mile run, pull-ups, 50 m swim and an obstacle course run. Both the GMT and SMT groups showed significant (p < 0.001) improvements in all physical tests. However, the SMT group produced significantly greater improvements in all four tests (pull-ups [p < 0.001], 50 m swim [p < 0.05], obstacle course [p < 0.01] and mile run [p < 0.01]) compared to the GMT group. Furthermore, different types of SMT (e.g. rock climbing and track sprinting) achieved greater improvements (p < 0.001–0.01) in certain physical tests when compared to other forms of SMT (e.g. Pankration, Fencing). These results indicate that cadets undertaking concurrent participation in general and sport military training are overall better prepared for physical performance than their counterparts who undertake only general military training. Military conditioning per sonnel should be aware of the positive interplay between general and sports specific training in forming a preparation strategy designed for physical performance.

There has been increasing interest in new measurement systems that provide instantaneous spatiotemporal data whilst being less expensive and more accessible to practitioners. The aim of this study was to examine the agreement between the OptoJump Next system (OJ), videography and force platform methods for measuring spatiotemporal variables during the acceleration phase of sprinting. Ninety-nine university students completed two maximal 20 metre sprints in which spatiotemporal parameters (contact time [CT], flight time [FT], step length [SL] and step rate) were simultaneously obtained using the OJ system (1000 Hz), videography (200 Hz), and force platforms (1000 Hz). The OJ and video systems showed high agreement for the measurement of step length (bias: 0.003-0.007 m, random error [RE]: 0.057-0.071 m). For temporal parameters, OJ tended to overestimate CT compared to the force platforms (bias: 0.012-0.014 s, RE: 0.009-0.021 s) and also underestimated FT (bias: 0.012-0.013 s, RE: 0.011-0.012 s). Despite the lower sampling rate, videography showed a closer agreement with the force platform for both CT (bias: 0.005-0.010 s, RE: 0.009-0.021 s) and FT (bias: 0.005-0.007 s, RE: 0.008-0.010 s). Although OptoJump next provides instantaneous spatiotemporal parameters, coaches may wish to adjust for the systematic overestimation of CT (0.013 s) and underestimation of FT (0.012 s) in order to obtain sprint spatiotemporal data that aligns to force platforms.

Research findings indicate that the inter-set rest interval is an important variable when prescribing resistance training (RT) programmes however, there is a growing focus of attention on the additional use of short intra-set rest intervals in the approach known as cluster set (CS) training. Despite evidence that supports the positive effects of CS configurations on the acute and chronic responses to RT, numerous challenges exist for practitioners when aiming to utilise this training concept. As such, this review aims to identify these challenges and offer recommendations in light of the contemporary research into this concept. The Discover, PubMed, Sport Discus, Research Gate and Google Scholar databases were searched in order to locate previous peer reviewed investigations which examined the acute and/or chronic responses to manipulating intra-set rest intervals. Twenty-five studies were reviewed after the inclusion criteria had been applied. Although the review highlighted that CS configurations may offer superior alternatives to traditional set configurations when seeking to emphasise specific acute or chronic responses, contrasting findings exist with regards to the chronic effects of CS configuration on various physical attributes (e.g. strength, power, hypertrophy) which presents challenges for practitioners when interpreting the literature. The contrasting findings result from a number of key methodological differences (e.g. intra-set rest duration) which practitioners need to be aware of when designing CS configurations. In terms of practical considerations, CS configurations may present challenges due to their time-consuming and monotonous nature but offer advantages in terms of reducing perceived exertion, cardiovascular demands, enhancing the performance and technique of key explosive exercises.

Purpose: The aim of this study was to investigate the associations between matched mechanical variables derived from both vertical and horizontal force-velocity-power (FVP) profiling, and the performance outcome variables within squat jump (SJ) and sprint performance. Methods: 20 elite male academy rugby league players (age 17.6±0.9 years; height 179.9±6.6cm; body mass 91.2±11.8kg) performed two maximal 40m sprints. The sprints were recorded using a radar gun device (Stalker ATS II, Applied Concepts, Dallas, TX, USA), which obtained instantaneous speed-time measurements. In addition, the participants performed two maximal SJ (∼90◦ knee angle) repetitions with these loads: 0kg, 20kg, 40kg, 60kg and 80kg. An Optojump (OptoJump Next Microgate, Bolzano, Italy) was used to record the SJ’s, which provided jump height (cm) for each load. Body mass relative vertical and horizontal mechanical variables (theoretical maximal values of force (F0) (N/kg), velocity (V0) (m/s), power (Pmax) (W/kg)) and the slope of the F-V linear relationship (Sfv) were calculated. Sprint performance was determined from the modelled velocity-time data (2m,5m,10m,20m sprint time (s) and Vmax (m/s). Pearson’s correlation coefficients (r) assessed the relationship between matched vertical and horizontal mechanical variables (F0 vertical & horizontal, v0 vertical & horizontal, Pmax vertical & horizontal and Sfv vertical & horizontal) and SJ and sprint performance. Results: Table 1. shows the correlations coefficient between the sprint and SJ force-velocity profiles and performance variables. There was no significant correlation between vertical and horizontal FVP matched mechanical variables (p > 0.05). The correlations between vertical FVP variables and sprint performance and between horizontal FVP variables and SJ performance failed to reach statistical significance (p > 0.05). Moderate -0.32 to near perfect 1.0 significant correlations (p < 0.05) were found between mechanical and performance variables shifting the importance of separate variables depending on the testing task. Conclusions: The absence of significant correlations between the vertical and horizontal FVP profiles suggests that they provide distinctive information about the athlete’s mechanical variables. The magnitude of the correlations between mechanical variables and sprint performance shifted across the velocity-time curve, therefore performance is determined by separate qualities depending on the distance. Whereas, Pmax reported the greatest correlation with SJ height. Practical Application: To ensure specific, accurate and comprehensive characterisation of athletes’ physical qualities FVP profiles should be determined with exercises maximal mechanically similarity to the targeted performance task. These results will aid practitioners in test selection the prescription and individualisation of training by providing important information as to the most influential variables to develop SJ and sprint performance.

Background Short-sprint (≤20m) performance is an important quality for success in the football codes. Therefore, developing an evidence base for understanding training methods to enhance short-sprint performance is key for practitioners. However, current systematic reviews are limited by 1) a lack of focus on football code athletes, 2) a lack of consideration of all training modalities, and 3) a failure to account for the normal training practices undertaken by intervention groups within their analysis. Therefore, this review aimed to 1) conduct a systematic review of the scientific literature evaluating training interventions upon short-sprint performance within football code athletes, 2) undertake a meta-analysis to assess the magnitude of change of sport-sprint performance following training interventions, and 3) identify how moderator variables affect the training response. Methods A systematic search of electronic databases was conducted. A random-effects meta-analysis was performed to establish standardised mean difference with 95% confidence intervals. This identified the magnitude and direction of the individual training effects of intervention subgroups (primary, secondary, combined-specific, tertiary and combined training methods) on short-sprint performance while considering moderator variables (i.e., football code, sex, age, playing standard, phase of season). Results 121 studies met the inclusion criteria, totalling 3,419 athletes. Significant improvements (small-large) were found between pre- and post-training in short-sprint performance for the combined, secondary, tertiary and combined-specific training methods. No significant effect was found for primary or sport only training. No individual mode was found to be the most effective. Between-subgroup analysis identified that football code, age, playing standard and phase of season all moderated the overall magnitude of training effects. Conclusions This review provides the largest systematic review and meta-analysis of short-sprint performance development methods and the only one to assess football code athletes exclusively. Practitioners can apply combined, secondary and tertiary training methods to improve short-sprint performance within football code athletes. The application of sport only and primary methods does not appear to improve short-sprint performance. Regardless of the population characteristics, short-sprint performance can be enhanced by increasing either or both the magnitude and the orientation of force an athlete can generate in the sprinting action.

Background Within the football codes, medium-distance (i.e., > 20 m and ≤ 40 m) and long-distance (i.e., > 40 m) sprint performance and maximum velocity sprinting are important capacities for success. Despite this, no research has identified the most effective training methods for enhancing medium- to long-distance sprint outcomes. Objectives This systematic review with meta-analysis aimed to (1) analyse the ability of different methods to enhance medium- to long-distance sprint performance outcomes (0–30 m, 0 to > 30 m, and the maximum sprinting velocity phase [Vmax]) within football code athletes and (2) identify how moderator variables (i.e., football code, sex, age, playing standard, phase of season) affected the training response. Methods We conducted a systematic search of electronic databases and performed a random-effects meta-analysis (within-group changes and pairwise between-group differences) to establish standardised mean differences (SMDs) with 95% confidence intervals and 95% prediction intervals. This identified the magnitude and direction of the individual training effects of intervention subgroups (sport only; primary, secondary, tertiary, and combined training methods) on medium- to long-distance sprint performance while considering moderator variables. Results In total, 60 studies met the inclusion criteria (26 with a sport-only control group), totalling 111 intervention groups and 1500 athletes. The within-group changes design reported significant performance improvements (small–moderate) between pre- and post-training for the combined, secondary (0–30 and 0 to > 30 m), and tertiary training methods (0–30 m). A significant moderate improvement was found in the Vmax phase performance only for tertiary training methods, with no significant effect found for sport only or primary training methods. The pairwise between-group differences design (experimental vs. control) reported favourable performance improvements (large SMD) for the combined (0 to > 30 m), primary (Vmax phase), secondary (0–30 m), and tertiary methods (all outcomes) when compared with the sport-only control groups. Subgroup analysis showed that the significant differences between the meta-analysis designs consistently demonstrated a larger effect in the pairwise between-group differences than the within-group change. No individual training mode was found to be the most effective. Subgroup analysis identified that football code, age, and phase of season moderated the overall magnitude of training effects. Conclusions This review provides the first systematic review and meta-analysis of all sprint performance development methods exclusively in football code athletes. Secondary, tertiary, and combined training methods appeared to improve medium-long sprint performance of football code athletes. Tertiary training methods should be implemented to enhance Vmax phase performance. Nether sport-only nor primary training methods appeared to enhance medium to long sprint performance. Performance changes may be attributed to either adaptations specific to the acceleration or Vmax phases, or both, but not exclusively Vmax. Regardless of the population characteristics, sprint performance can be enhanced by increasing either the magnitude or the orientation of force an athlete can generate in the sprinting action, or both.

This cross-sectional study evaluated the sprint and jump mechanical profiles of male academy rugby league players, the differences between positions, and the associations between mechanical profiles and sprint performance. Twenty academy rugby league players performed 40-m sprints and squat jumps at increasing loads (0-80 kg) to determine individual mechanical (force-velocity-power) and performance variables. The mechanical variables (absolute and relative theoretical maximal force-velocity-power, force-velocity linear relationship, and mechanical efficiency) were determined from the mechanical profiles. Forwards had significantly (p < 0.05) greater vertical and horizontal force, momentum but jumped lower (unloaded) and were slower than backs. No athlete presented an optimal jump profile. No associations were found between jump and sprint mechanical variables. Absolute theoretical maximal vertical force significantly (p < 0.05) correlated (r = 0.71-0.77) with sprint momentum. Moderate (r = -0.47) to near-perfect (r = 1.00) significant associations (p < 0.05) were found between sprint mechanical and performance variables. The largest associations shifted from maximum relative horizontal force-power generation and application to maximum velocity capabilities and force application at high velocities as distance increased. The jump and sprint mechanical profiles appear to provide distinctive and highly variable information about academy rugby league players' sprint and jump capacities. Associations between mechanical variables and sprint performance suggest horizontal and vertical profiles differ and should be trained accordingly.

Within the football codes, sprint performance is considered an important capacity for success and is therefore targeted as an area of athletic development programmes. However, the concurrent and complex nature of physical preparation for the football codes presents several challenges for effective sprint development. This thesis aimed to evaluate and enhance the understanding of the development of sprint performance in football code athletes to support the delivery of best practices. This thesis is comprised of sequential sections presented through a series of chapters. First, systematic reviews with meta-analyses to evaluate the evidence base for the development of sprint performance (short- and medium-long distances). Second, a practitioner survey analysing the applied training practices and justifications for the organisation and evaluation of the sprint development. The last section provides observations and evaluation of profiling methods for phase and distance-specific sprint performance using a case study of combined training methodologies in elite male youth rugby league athletes. The systematic review and meta-analysis showed sport-only training and short sprints with incomplete rest appear to be insufficient to enhance sprint performance in football code athletes. Instead, sprint development requires either or preferably a combined method approach to both improving sprinting skills (i.e., sprints performed with overload (physical or co-coordinative)) and the athlete's physical characteristics (i.e., plyometrics and resistance training). Combined with the surveys and case studies this research showed that a one size fits all approach to sprint development (i.e., exercises, loading ect.) is not applicable; instead, effective training strategies depend upon the individuals and context that it is applied. Therefore, the content of the training (e.g., training frequency, exercise selection, training load prescription) is highly variable in research and practice, but so is the training response. Applying frequent and embedded monitoring of key variables (i.e., mechanical profiling) can support personalised and potentially improved training practices. Sprint development in football code practice is challenging (particularly long-term) due to the complexity and at times, competing requirements of an athlete’s development. Therefore, if an individual or team of football code athletes aims to enhance sprint performance, it requires prioritisation from all the key stakeholders.

Abstract

Measurements of muscle-tendon unit (MTU) function can be categorised into local (e.g. tendon strain) or global (e.g. jump height) assessments. Although menstrual cycle phase may be a key consideration when implementing these assessments in female athletes, the reliability of many MTU assessments is not well defined within female populations. Therefore, the purpose of this study was to report the test-retest reliability of local and global MTU function assessments during the early follicular phase of the menstrual cycle. Seventeen naturally menstruating females (age 28.5 ± 7.3 years) completed local and global assessments of MTU function during two testing sessions separated over 24-72 hours. Local tests included Achilles’ tendon mechanical testing and isometric strength of ankle plantar flexors and knee extensors, whereas global tests included countermovement, squat, and drop jumps, and the isometric midthigh pull. Based on intraclass correlation coefficient (ICC) statistics, poor to excellent reliability was found for local measures (ICC: 0.096-0.936). Good to excellent reliability was found for all global measures (ICC: 0.788-0.985), excluding the eccentric utilisation ratio (ICC 0.738) and most rate of force development metrics (ICC: 0.635-0.912). Isometric midthigh pull peak force displayed excellent reliability (ICC: 0.966), whereas force-time metrics ranged from moderate to excellent (ICC: 0.635-0.970). Excluding rate of force development (coefficient of variation [CV]: 10.6-35.9%), global measures (CV: 1.6-12.9%) were more reproducible than local measures (CV: 3.6-64.5%). However, local metrics directly measure specific aspects of MTU function, and therefore provide valuable information despite lower reproducibility. The novel data reported here provides insight into the natural variability of MTU function within female athletes, which can be used to enhance the interpretation of other female athlete data, especially that which aims to investigate other aspects of variability, such as the menstrual cycle.

Despite the importance and complexity of developing sprint performance in football code athletes, there are limited studies exploring practitioners’ practices to improve sprinting. Therefore, this study aimed to describe and evaluate the practices used with elite football code athletes to develop sprint performance. Ninety subjects completed a survey comprised of four sections (coaching demographic, evaluation of training, organisation of training, and training protocols). Survey responses showed that 98% of practitioners monitor sprint performance, and 92% integrated monitoring strategies into sprint development programmes to inform training. All practitioners used combined training methods including specific (e.g., sprints with or without overload) and non-specific (e.g., strength training or plyometrics) methods targeting the underpinning determinants of sprint performance. Most practitioners reported prescribing 1-3 or 2-4 days·wk-1 for sprint development, both in-season and pre-season. Sprint development programmes were uncommon in the off-season. Most specific sprint training sessions were reportedly shorter in duration (5-15 and 15-30 min) than non-specific sprint training methods (30-45 and >45 min) irrespective of the season phases. Sprint development was integrated before and after sport-specific training, regularly using warm-ups and gym sessions. Specific training methods were also implemented in separate sessions. The specific content (e.g., exercise selection, training load prescription) was highly variable between practitioners. This study represents the first detailed survey (practices and justification) of sprint development practices (evaluation and organisation of training protocols) in football code cohorts. These findings present multiple methods of structuring, integrating and manipulating sprint training based on the training aims and the individual context.