Strengthening the Practice of Exercise and Sport-Science Research

Caffeine Placebo Effect in Sport and Exercise: A Systematic Review

The objective of this review article is to systematically identify the caffeine placebo effect in sport and exercise activities. We selected randomized controlled trial studies to better understand the impact of caffeine and its placebo effect on sports performance. We extracted a set of articles that refer strictly to the topics of caffeine and its placebo effect in sport and exercise, considering the databases integrated to the Core Collection Web of Science and Scopus, as well as the registration of the documents in PubMed®, a system with a selection process aligned with the guidelines for the PRISMA methodology, establishing the eligibility criteria of the articles with the PICOS tool, to which a systematic review is applied. Finally, the results show that caffeine improves anaerobic capacity and endurance, while placebo perceived as caffeine can also increase performance by reducing pain and improving concentration. This finding underscores the influence of expectations and placebo on physical performance, suggesting that managing these expectations may be an effective strategy for improving athletic performance.

Replication study: Investigating the effects of maximal anaerobic fatigue on dynamic postural control using the Y-Balance Test

OBJECTIVES

The aim of this study was to replicate the study titled "Investigating the effects of maximal anaerobic fatigue on dynamic postural control using the Y-Balance Test" by Johnston et al. (2018) as part of a large replication project. This study aimed to determine the effects of maximal anaerobic fatigue on dynamic postural control using the Y-Balance Test, with a specific focus on anterior reach distance.

DESIGN

A single session intervention.

METHODS

Forty male and female university students (age: 22 ± 3 years, height: 171.88 ± 8.96 cm, mass: 76.20 ± 14.31 kg) partaking in competitive sport, completed a Y-Balance Test protocol at 20, 10, and 0 min before a modified 60 s Wingate fatiguing protocol. Post-fatigue assessments were completed at 0, 10, and 20 min after the Wingate test. Replication outcomes included significance, direction, and effect size comparison using a z-test.

RESULTS

A one-way repeated measures ANOVA showed a significant effect for maximal anaerobic fatigue on normalised anterior reach direction (F1.82, 69.03 = 7.16, p = 0.002, ηp2 = 0.159; 95 % CI: 0.025, 0.320). Therefore, we replicated the original findings for anterior reach distance in terms of statistical significance (F = 3.818, p = 0.025, ηp2 = 0.376; 95 % CI: 0.00, 0.62). The replication and original effect size estimates for anterior reach direction were compared using a z-test and were deemed compatible (z = 1.65, p = 0.05).

CONCLUSIONS

Overall, we replicated the original study findings for the effect of maximal anaerobic fatigue on anterior reach distance in a Y-Balance Test.

Injury and illness surveillance monitoring in team sports: a framework for all

BACKGROUND

Sport-related injuries and illnesses can negatively impact athlete welfare at all standards of participation in team sports. Injury and illness surveillance (IIS), and the development of monitoring systems, initiates the sequence of injury and illness prevention. Operational IIS monitoring systems help to appraise epidemiological estimates of injury and illness incidence and burden in various athlete populations. However, the methodological underpinnings of various monitoring systems are not harmonized or widely documented, with the presence of efficient and successful programmes rarely showcased at non-elite levels. The aim is to provide a framework that guides the development of IIS, which will enhance overall surveillance, to indirectly inform injury prevention strategies.

METHODS

The process involved all members of the research group initially discussing the research gaps, scope of the project, and the aims of the article. Unique experiences were shared, and specific and global challenges and barriers to IIS at all standards of team sport participation were identified. A tiered system of data collection with corresponding content were produced, with experiences and guidance provided throughout the article.

RESULTS

The literature has been reviewed and using first-hand experience in conducting IIS programmes in complex and diverse sport settings, the authors have identified key enablers and barriers for best practise as time, technological and human resources, reporter/practitioner training, and medical expertise. Areas of greatest importance regarding the conducting of IIS have been outlined, providing guidance and recommendations across all levels of team sport participation. These areas include definitions, data context, collection procedures, handling, security, ethics, storage, dissemination, quality, compliance, and analysis. Given the barriers to IIS, 3-tiered levels of data collection and content have been proposed. The levels indicate data collection variables, with a focus on sufficiency and achievability, aiming to support the successful conducting of IIS in team sports across all standards of participation. Future opportunities in IIS have been discussed, with several predictive measures and analytical techniques expanded upon.

CONCLUSIONS

The framework provides universal guidance for implementing IIS monitoring systems, facilitating athletes, coaches, parents/guardians, governing bodies and practitioners to implement IIS processes, identify challenges, complete analysis, and interpret outcomes at all standards of participation.

Longitudinal Meta-Analysis of Peak Height Velocity in Young Female Athletes

Growth patterns and biological milestones in youth sports are key to interpreting the development of young athletes. However, there is no analysis of longitudinal meta-analysis describing the growth of young female athletes. This longitudinal meta-analysis estimated growth curves and age at peak height velocity (PHV) in young female athletes based on anthropometric data from longitudinal studies found in the literature. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, studies with repeated measurements in young female athletes were identified from searches of four databases (MEDLINE, Web of Science, SCOPUS, and SPORTDiscus) without date restrictions through August 2023. We adapted our bias assessment criteria using the Cochrane risk of bias tool for randomized controlled trials as a reference. Bayesian multilevel modeling was used to perform a longitudinal meta-analysis to extract stature growth curves and age at PHV. Fourteen studies met our eligibility criteria. Twenty-one independent samples could be included in the analysis. Conditional on the data and models, the predicted mean age at PHV for female athletes was 11.18 years (90% CI: 8.62; 12.94). When studies were aggregated by sport in the models, the models could not capture sport-specific growth curves for stature and estimate a corresponding age at PHV. We provide the first longitudinal meta-analytic summary of pubertal growth and derive age at PHV in young female athletes. The meta-analysis predicted that age at PHV occurs at similar ages to those in the general pediatric population. The data pool was limited in sports and geographic distribution, emphasizing the need to promote longitudinal research in females across different youth sports contexts.

Certainty of Evidence Assessment in Systematic Reviews Published by High-Impact Sports Science Journals: A Meta-epidemiological Study

BACKGROUND

Assessing certainty of evidence is a key element of any systematic review. The aim of this meta-epidemiology study was to understand the frequency and ways with which certainty of evidence is assessed in contemporary systematic reviews published in high-impact sports science journals.

METHODS

We searched PubMed and relevant journal web sites from 1 August 2016 to 11 October 2022 for systematic reviews published in the top-ten highest-impact journals within the 2020 Journal Citation Report for the Sports Sciences category. Pairs of independent reviewers screened items using a priori established criteria.

RESULTS

Of 1250 eligible documents, 258 (20.6%) assessed the certainty of evidence, defined as using two or more distinct domains to provide an overall rating of the trustworthiness of findings across studies. Nine methods were cited for assessing certainty, with the most common being the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach (61.6%). The proportion of systematic reviews assessing certainty of evidence appeared to increase over the 6-year timeframe analyzed. Across all reviews analyzed, a large majority addressed the domains of risk of bias, imprecision, and inconsistency of the results. Other certainty domains including indirectness/applicability were less commonly assessed.

DISCUSSION

Only one in five recent contemporary systematic reviews in the field of exercise and sports science assessed certainty of evidence. Organizational and institutional education on methods for assessing evidence may help further increase uptake of these methods and improve both the quality and clinical impact of systematic reviews in the field.

Preferred Reporting Items for Resistance Exercise Studies (PRIRES): A Checklist Developed Using an Umbrella Review of Systematic Reviews

BACKGROUND

The issues of replication and scientific transparency have been raised in exercise and sports science research. A potential means to address the replication crisis and enhance research reliability is to improve reporting quality and transparency. This study aims to formulate a reporting checklist as a supplement to the existing reporting guidelines, specifically for resistance exercise studies.

METHODS

PubMed (which covers Medline) and Scopus (which covers Medline, EMBASE, Ei Compendex, World Textile Index, Fluidex, Geobase, Biobase, and most journals in Web of Science) were searched for systematic reviews that comprised the primary studies directly comparing different resistance training methods. Basic data on the selected reviews, including on authors, publication years, and objectives, were summarized. The reporting items for the checklist were identified based on the objective of the reviews. Additional items from an existing checklist, namely the Consensus on Exercise Reporting Template, a National Strength and Conditioning Association handbook, and an article from the EQUATOR library were incorporated into the final reporting checklist.

RESULTS

Our database search retrieved 3595 relevant records. After automatic duplicate removal, the titles and abstracts of the remaining 2254 records were screened. The full texts of 137 records were then reviewed, and 88 systematic reviews that met the criteria were included in the umbrella review.

CONCLUSION

Developed primarily by an umbrella review method, this checklist covers the research questions which have been systematically studied and is expected to improve the reporting completeness of future resistance exercise studies. The PRIRES checklist comprises 26 reporting items (39 subitems) that cover four major topics in resistance exercise intervention: 1) exercise selection, performance, and training parameters, 2) training program and progression, 3) exercise setting, and 4) planned vs actual training. The PRIRES checklist was designed specifically for reporting resistance exercise intervention. It is expected to be used with other reporting guidelines such as Consolidated Standards of Reporting Trials and Standard Protocol Items: Recommendations for Interventional Trials. This article presents only the development process and resulting items of the checklist. An accompanying article detailing the rationale for, the importance of, and examples of each item is being prepared.

REGISTRATION

This study is registered with the EQUATOR Network under the title "Preferred Reporting Items for Resistance Exercise Studies (PRIRES)." PROSPERO registration number: CRD42021235259.

Revisiting the effect of team passion displayed during national anthems on subsequent success: A replication and extension

Slater et al. (2018. Singing it for "us": Team passion displayed during national anthems is associated with subsequent success. European Journal of Sport Science, 18(4), 541-549. https://doi.org/10.1080/17461391.2018.1431311) found that the perceived level of team passion displayed during (pre-match) national anthems at UEFA Euro 2016 predicted team performance during the match. Teams that displayed greater passion conceded fewer goals and team passion predicted the likelihood of victory during the knockout (but not group) stages. Here, we replicate Slater et al. using a larger sample of matches from the FIFA World Cup (n = 415), and apply more appropriate analyses, and control for potential confounds. We also extend the original study to consider additional performance-related outcome variables (fouls, bookings, and possession). We find no evidence that anthem passion was a reliable predictor of performance outcomes (i.e. match outcome, goals scored/conceded, fouls, bookings, possession) in competitive international soccer matches.HIGHLIGHTSFailing to replicate previous research, we find no evidence that the amount of collective passion displayed by a team during the national anthem predicts performance outcomes in soccer matches.Collective passion was unrelated to goals scored, goals conceded, match outcome, fouls, possession, and expected goals. The effect of passion on these outcomes was not moderated by the stage of competition.The reported null effects may be because verbal and non-verbal behaviours during the national anthem are poor signals of collective passion.

Tutorial. Surface electromyogram (sEMG) amplitude estimation: Best practices

This tutorial intends to provide insight, instructions and "best practices" for those who are novices-including clinicians, engineers and non-engineers-in extracting electromyogram (EMG) amplitude from the bipolar surface EMG (sEMG) signal of voluntary contractions. A brief discussion of sEMG amplitude extraction from high density sEMG (HDsEMG) arrays and feature extraction from electrically elicited contractions is also provided. This tutorial attempts to present its main concepts in a straightforward manner that is accessible to novices in the field not possessing a wide range of technical background (if any) in this area. Surface EMG amplitude, also referred to as the sEMG envelope [often implemented as root mean square (RMS) sEMG or average rectified value (ARV) sEMG], quantifies the voltage variation of the sEMG signal and is grossly related to the overall neural excitation of the muscle and to peripheral parameters. The tutorial briefly reviews the physiological origin of the voluntary sEMG signal and sEMG recording, including electrode configurations, sEMG signal transduction, electronic conditioning and conversion by an analog-to-digital converter. These topics have been covered in greater detail in prior tutorials in this series. In depth descriptions of state-of-the-art methods for computing sEMG amplitude are then provided, including guidance on signal pre-conditioning, absolute value vs. square-law detection, selection of appropriate sEMG amplitude smoothing filters and attenuation of measurement noise. The tutorial provides a detailed list of best practices for sEMG amplitude estimation.

Changes in countermovement jump force-time characteristic in elite male basketball players: A season-long analyses

Basketball is a sport that is characterized by various physical performance parameters and motor abilities such as speed, strength, and endurance, which are all underpinned by an athlete's efficient use of the stretch-shortening cycle (SSC). A common assessment to measure SSC efficiency is the countermovement jump (CMJ). When performed on a force plate, a plethora of different force-time metrics may be gleaned from the jump task, reflecting neuromuscular performance characteristics. The aim of this study was to investigate how different CMJ force-time characteristics change across different parts of the athletic year, within a sample of elite collegiate male basketball players. Twelve basketball players performed CMJ's on near-weekly basis, combining for a total of 219 screenings. The span of testing was broken down into four periods: pre-season, non-conference competitive period, conference competitive period, and post-season competitive period. Results suggest that basketball players were able to experience improvements and maintenance of performance with regards to various force-time metrics, transitioning from the pre-season period into respective later phases of the in-season period. A common theme was a significant improvement between the pre-season period and the non-conference period. Various force-time metrics were subject to change, while outcome metrics such as jump height remained unchanged, suggesting that practitioners are encouraged to more closely monitor how different force-time characteristics change over extended periods of time.

Increased Cortical Activity in Novices Compared to Experts During Table Tennis: A Whole-Brain fNIRS Study Using Threshold-Free Cluster Enhancement Analysis

There is a growing interest to understand the neural underpinnings of high-level sports performance including expertise-related differences in sport-specific skills. Here, we aimed to investigate whether expertise level and task complexity modulate the cortical hemodynamics of table tennis players. 35 right-handed table tennis players (17 experts/18 novices) were recruited and performed two table tennis strokes (forehand and backhand) and a randomized combination of them. Cortical hemodynamics, as a proxy for cortical activity, were recorded using functional near-infrared spectroscopy, and the behavioral performance (i.e., target accuracy) was assessed via video recordings. Expertise- and task-related differences in cortical hemodynamics were analyzed using nonparametric threshold-free cluster enhancement. In all conditions, table tennis experts showed a higher target accuracy than novices. Furthermore, we observed expertise-related differences in widespread clusters compromising brain areas being associated with sensorimotor and multisensory integration. Novices exhibited, in general, higher activation in those areas as compared to experts. We also identified task-related differences in cortical activity including frontal, sensorimotor, and multisensory brain areas. The present findings provide empirical support for the neural efficiency hypothesis since table tennis experts as compared to novices utilized a lower amount of cortical resources to achieve superior behavioral performance. Furthermore, our findings suggest that the task complexity of different table tennis strokes is mirrored in distinct cortical activation patterns. Whether the latter findings can be useful to monitor or tailor sport-specific training interventions necessitates further investigations.

Training in the Initial Range of Motion Promotes Greater Muscle Adaptations Than at Final in the Arm Curl

OBJECTIVE

The effects of ROM manipulation on muscle strength and hypertrophy response remain understudied in long-term interventions. Thus, we compared the changes in strength and regional muscle hypertrophy after training in protocols with different ranges of motion (ROM) in the seated dumbbell preacher curl exercise using a within-participant experimental design.

DESIGN AND METHODS

Nineteen young women had one arm randomly assigned to train in the initial ROM (INITIALROM: 0°-68°; 0° = extended elbow) while the contralateral arm trained in the final ROM (FINALROM: 68°-135°), three times per week over an eight-week study period. Pre- and post-training assessments included one repetition maximum (1RM) testing in the full ROM (0°-135°), and measurement of biceps brachii cross-sectional area (CSA) at 50% and 70% of humerus length. Paired t-tests were used to compare regional CSA changes between groups, the sum of CSA changes at 50% and 70% (CSAsummed), and the strength response between the training protocols.

RESULTS

The INITIALROM protocol displayed a greater CSA increase than FINALROM protocol at 70% of biceps length (p = 0.001). Alternatively, we observed similar increases between the protocols for CSA at 50% (p = 0.311) and for CSAsummed (p = 0.111). Moreover, the INITIALROM protocol displayed a greater 1RM increase than FINALROM (p < 0.001).

CONCLUSIONS

We conclude that training in the initial angles of elbow flexion exercise promotes greater distal hypertrophy of the biceps brachii muscle in untrained young women. Moreover, the INITIALROM condition promotes a greater dynamic strength increase when tested at a full ROM compared to the FINALROM.

Proposal of a Selection Protocol for Replication of Studies in Sports and Exercise Science

INTRODUCTION

To improve the rigor of science, experimental evidence for scientific claims ideally needs to be replicated repeatedly with comparable analyses and new data to increase the collective confidence in the veracity of those claims. Large replication projects in psychology and cancer biology have evaluated the replicability of their fields but no collaborative effort has been undertaken in sports and exercise science. We propose to undertake such an effort here. As this is the first large replication project in this field, there is no agreed-upon protocol for selecting studies to replicate. Criticism of previous selection protocols include claims they were non-randomised and non-representative. Any selection protocol in sports and exercise science must be representative to provide an accurate estimate of replicability of the field. Our aim is to produce a protocol for selecting studies to replicate for inclusion in a large replication project in sports and exercise science.

METHODS

The proposed selection protocol uses multiple inclusion and exclusion criteria for replication study selection, including: the year of publication and citation rankings, research disciplines, study types, the research question and key dependent variable, study methods and feasibility. Studies selected for replication will be stratified into pools based on instrumentation and expertise required, and will then be allocated to volunteer laboratories for replication. Replication outcomes will be assessed using a multiple inferential strategy and descriptive information will be reported regarding the final number of included and excluded studies, and original author responses to requests for raw data.

Replication concerns in sports and exercise science: a narrative review of selected methodological issues in the field

Known methodological issues such as publication bias, questionable research practices and studies with underpowered designs are known to decrease the replicability of study findings. The presence of such issues has been widely established across different research fields, especially in psychology. Their presence raised the first concerns that the replicability of study findings could be low and led researchers to conduct large replication projects. These replication projects revealed that a significant portion of original study findings could not be replicated, giving rise to the conceptualization of the replication crisis. Although previous research in the field of sports and exercise science has identified the first warning signs, such as an overwhelming proportion of significant findings, small sample sizes and lack of data availability, their possible consequences for the replicability of our field have been overlooked. We discuss the consequences of the above issues on the replicability of our field and offer potential solutions to improve replicability.

Effects of Mindfulness for Performance Programme on Actual Performance in Ecological Sport Context: Two Studies in Basketball and Table Tennis

Mindfulness For Performance is a programme that has been developed over 15 years. It aims to help athletes maintain effective attentional focus regardless of the disruptive sensations and thoughts induced by the performance situation. It is inspired by Mindfulness Based Stress Reduction and Acceptance Commitment Therapy programmes and has been adapted to the specificities of sport. It is composed of three steps: (a) psychoeducation and identification of the focus of attention, (b) mindfulness and acceptance training, and (c) integrating skills acquired into training and competition. This article reports the effects of MFP in two studies in national basketball players and in young table tennis players. The first study showed that mindfulness skills and free-throw accuracy during basketball games increased more in the experimental group than in the control group. Table tennis results revealed that participants who showed the highest percentage of adherence to the programme benefited more from MFP training in terms of performance outcome (i.e., accumulated points collected from published results compared with the baseline phase) than participants who showed weaker percentages of adherence to the programme. Both studies provided some evidence on the effects of MFP on specific performance indicators (i.e., free-throw accuracy in basketball and ranking points in table tennis), but this needs to be confirmed by further research measuring other relevant performance indicators. The impact and conditions of adherence also deserve more consideration.

Reporting and transparent research practices in sports medicine and orthopaedic clinical trials: a meta-research study

OBJECTIVES

Transparent reporting of clinical trials is essential to assess the risk of bias and translate research findings into clinical practice. While existing studies have shown that deficiencies are common, detailed empirical and field-specific data are scarce. Therefore, this study aimed to examine current clinical trial reporting and transparent research practices in sports medicine and orthopaedics.

SETTING

Exploratory meta-research study on reporting quality and transparent research practices in orthopaedics and sports medicine clinical trials.

PARTICIPANTS

The sample included clinical trials published in the top 25% of sports medicine and orthopaedics journals over 9 months.

PRIMARY AND SECONDARY OUTCOME MEASURES

Two independent reviewers assessed pre-registration, open data and criteria related to scientific rigour, like randomisation, blinding, and sample size calculations, as well as the study sample, and data analysis.

RESULTS

The sample included 163 clinical trials from 27 journals. While the majority of trials mentioned rigour criteria, essential details were often missing. Sixty per cent (95% confidence interval (CI) 53% to 68%) of trials reported sample size calculations, but only 32% (95% CI 25% to 39%) justified the expected effect size. Few trials indicated the blinding status of all main stakeholders (4%; 95% CI 1% to 7%). Only 18% (95% CI 12% to 24%) included information on randomisation type, method and concealed allocation. Most trials reported participants' sex/gender (95%; 95% CI 92% to 98%) and information on inclusion and exclusion criteria (78%; 95% CI 72% to 84%). Only 20% (95% CI 14% to 26%) of trials were pre-registered. No trials deposited data in open repositories.

CONCLUSIONS

These results will aid the sports medicine and orthopaedics community in developing tailored interventions to improve reporting. While authors typically mention blinding, randomisation and other factors, essential details are often missing. Greater acceptance of open science practices, like pre-registration and open data, is needed. As these practices have been widely encouraged, we discuss systemic interventions that may improve clinical trial reporting.

Feasibility of an Audit and Feedback Intervention to Facilitate Journal Policy Change Towards Greater Promotion of Transparency and Openness in Sports Science Research

OBJECTIVES

To evaluate (1) the feasibility of an audit-feedback intervention to facilitate sports science journal policy change, (2) the reliability of the Transparency of Research Underpinning Social Intervention Tiers (TRUST) policy evaluation form, and (3) the extent to which policies of sports science journals support transparent and open research practices.

METHODS

We conducted a cross-sectional, audit-feedback, feasibility study of transparency and openness standards of the top 38 sports science journals by impact factor. The TRUST form was used to evaluate journal policies support for transparent and open research practices. Feedback was provided to journal editors in the format of a tailored letter. Inter-rater reliability and agreement of the TRUST form was assessed using intraclass correlation coefficients and the standard error of measurement, respectively. Time-based criteria, fidelity of intervention delivery and qualitative feedback were used to determine feasibility.

RESULTS

The audit-feedback intervention was feasible based on the time taken to rate journals and provide tailored feedback. The mean (SD) score on the TRUST form (range 0-27) was 2.05 (1.99), reflecting low engagement with transparent and open practices. Inter-rater reliability of the overall score of the TRUST form was moderate [ICC (2,1) = 0.68 (95% CI 0.55-0.79)], with standard error of measurement of 1.17. However, some individual items had poor reliability.

CONCLUSION

Policies of the top 38 sports science journals have potential for improved support for transparent and open research practices. The feasible audit-feedback intervention developed here warrants large-scale evaluation as a means to facilitate change in journal policies.

REGISTRATION

OSF ( https://osf.io/d2t4s/ ).

Assessing Open Science practices in physical activity behaviour change intervention evaluations

Objectives

Concerns on the lack of reproducibility and transparency in science have led to a range of research practice reforms, broadly referred to as 'Open Science'. The extent that physical activity interventions are embedding Open Science practices is currently unknown. In this study, we randomly sampled 100 reports of recent physical activity randomised controlled trial behaviour change interventions to estimate the prevalence of Open Science practices.

Methods

One hundred reports of randomised controlled trial physical activity behaviour change interventions published between 2018 and 2021 were identified, as used within the Human Behaviour-Change Project. Open Science practices were coded in identified reports, including: study pre-registration, protocol sharing, data, materials and analysis scripts sharing, replication of a previous study, open access publication, funding sources and conflict of interest statements. Coding was performed by two independent researchers, with inter-rater reliability calculated using Krippendorff's alpha.

Results

78 of the 100 reports provided details of study pre-registration and 41% provided evidence of a published protocol. 4% provided accessible open data, 8% provided open materials and 1% provided open analysis scripts. 73% of reports were published as open access and no studies were described as replication attempts. 93% of reports declared their sources of funding and 88% provided conflicts of interest statements. A Krippendorff's alpha of 0.73 was obtained across all coding.

Conclusion

Open data, materials, analysis and replication attempts are currently rare in physical activity behaviour change intervention reports, whereas funding source and conflict of interest declarations are common. Future physical activity research should increase the reproducibility of their methods and results by incorporating more Open Science practices.

Sample size justifications in Gait & Posture

BACKGROUND

Context regarding how researchers determine the sample size of their experiments is important for interpreting the results and determining their value and meaning. Between 2018 and 2019, the journal Gait & Posture introduced a requirement for sample size justification in their author guidelines.

RESEARCH QUESTION

How frequently and in what ways are sample sizes justified in Gait & Posture research articles and was the inclusion of a guideline requiring sample size justification associated with a change in practice?

METHODS

The guideline was not in place prior to May 2018 and was in place from 25th July 2019. All articles in the three most recent volumes of the journal (84-86) and the three most recent, pre-guideline volumes (60-62) at time of preregistration were included in this analysis. This provided an initial sample of 324 articles (176 pre-guideline and 148 post-guideline). Articles were screened by two authors to extract author data, article metadata and sample size justification data. Specifically, screeners identified if (yes or no) and how sample sizes were justified. Six potential justification types (Measure Entire Population, Resource Constraints, Accuracy, A priori Power Analysis, Heuristics, No Justification) and an additional option of Other/Unsure/Unclear were used.

RESULTS

In most cases, authors of Gait & Posture articles did not provide a justification for their study's sample size. The inclusion of the guideline was associated with a modest increase in the percentage of articles providing a justification (16.6-28.1%). A priori power calculations were the dominant type of justification, but many were not reported in enough detail to allow replication.

SIGNIFICANCE

Gait & Posture researchers should be more transparent in how they determine their sample sizes and carefully consider if they are suitable. Editors and journals may consider adding a similar guideline as a low-resource way to improve sample size justification reporting.

Measurement properties of external training load variables during standardised games in soccer: Implications for training and monitoring strategies

The aim of this study was to assess the measurement properties of external training load measures across three formats of standardised training games. Eighty-eight players from two English professional soccer clubs participated in the study spanning three consecutive seasons. External training load data was collected from three types of standardised game format drills (11v11, 10v10, 7v7+6) using Global Positioning Systems. For each external training load metric in each game format, the following measurement properties were calculated; coefficient of variation (CV%) to determine between- and within-subject reliability, intraclass coefficient correlation (ICC) to determine test-retest reliability, and signal-to-noise ratio (SNR) to determine sensitivity. Total distance (TD) and PlayerLoad^™ (PL) demonstrated good sensitivity (TD SNR = 1.6–4.6; PL SNR = 1.2–4.3) on a group level. However, a wide variety of within-subject reliability was demonstrated for these variables (TD CV% = 1.7–36.3%; PL CV% = 4.3–39.5%) and corresponding intensity measures calculated per minute. The percentage contribution of individual planes to PL showed the lowest between-subject CV% (CV% = 2–7%), although sensitivity varied across formats (SNR = 0.3–1.4). High speed running demonstrated poor reliability across all three formats of SSG (CV% = 51–103%, ICC = 0.03–0.53). Given the measurement properties of external training load measures observed in this study, specifically the within-subject variation, reliability across trials of standardised training games should be calculated on an individual level. This will allow practitioners to detect worthwhile changes across trials of standardised game format drills. Such information is important for the appropriate implementation of training and monitoring strategies in soccer.

Myths and Methodologies: The use of equivalence and non-inferiority tests for interventional studies in exercise physiology and sport science

NEW FINDINGS

What is the topic of this review? The traditional null-hypothesis test allows making informed decisions about whether an experimental intervention is superior to a control while controlling the Type I and Type II error rates. Equivalence and non-inferiority tests allow determining whether two interventions are similar in efficacy or whether one is not unacceptably worse than the other. What advances does it highlight? Equivalence and non-inferiority designs may better fit the research questions of exercise physiologists and sport scientists when investigating new interventions that have better cost-effectiveness, are safer and easier to implement, or are less demanding than the standard.

ABSTRACT

Exercise physiology and sport science have traditionally made use of the null hypothesis of no difference to make decisions about experimental interventions. This article aims to review current statistical approaches typically used by exercise physiologists and sport scientists for the design and analysis of experimental interventions and to highlight the importance of including equivalence and non-inferiority studies, which address different research questions than deciding whether an effect is present. Firstly, we briefly describe the most common approaches, along with their rationale, to investigate the effects of different interventions. We then discuss the main steps involved in the design and analysis of equivalence and non-inferiority studies, commonly performed in other research fields, with worked examples from exercise physiology and sport science scenarios. Finally, we provide recommendations to exercise physiologists and sport scientists who would like to apply the different approaches in future research. We hope this work will promote the correct use of equivalence and non-inferiority designs in exercise physiology and sport science whenever the research context, conditions, applications, researchers' interests, or reasonable beliefs, justify these approaches. This article is protected by copyright. All rights reserved.

Relationship between explosive strength characteristics with change of direction speed in junior and cadet karate athletes

BACKGROUND: Explosive strength and change of direction speed (CODS) are relevant physical abilities in karate. OBJECTIVE: To examine the relationship between the characteristics of explosive strength and the 5-m linear sprint (5M) with CODS performance and ii) to examine the influential characteristics of explosive strength on CODS performance. METHODS: Eighteen cadet and junior karate athletes, eight females and ten males were evaluated. The physical abilities assessments included: squat jump (SJ), countermovement jump (CMJ), 5M and CODS. Also, pre-stretch percentage increase (PSA), eccentric utilization index (EUR) reactive strength index (RSI) were calculated. RESULTS: Superior performance (p< 0.05) was documented in SJ, CMJ and CODS in male vs. female. Also, significant correlations between CODS with SJ and CMJ (r=-0.70 to -0.80; R2=-0.51 to -0.73; p< 0.05, respectively) and correlations (r=-0.14 to -0.22; R2= 0.01 to 0.04; p> 0.05) between CODS with RSI, EUR and PSA. Multiple regression model documented that only SJ significantly influenced CODS performance in male (R2= 60%; p= 0.009) and female (R2= 71%; p= 0.001). CONCLUSION: CODS correlate with SJ and CMJ. In particular, SJ influence CODS independently of gender.

Always Pay Attention to Which Model of Motor Learning You Are Using

This critical review considers the epistemological and historical background of the theoretical construct of motor learning for a more differentiated understanding. More than simply reflecting critically on the models that are used to solve problems-whether they are applied in therapy, physical education, or training practice-this review seeks to respond constructively to the recent discussion caused by the replication crisis in life sciences. To this end, an in-depth review of contemporary motor learning approaches is provided, with a pragmatism-oriented clarification of the researcher's intentions on fundamentals (what?), subjects (for whom?), time intervals (when?), and purpose (for what?). The complexity in which the processes of movement acquisition, learning, and refinement take place removes their predictable and linear character and therefore, from an applied point of view, invites a great deal of caution when trying to make generalization claims. Particularly when we attempt to understand and study these phenomena in unpredictable and dynamic contexts, it is recommended that scientists and practitioners seek to better understand the central role that the individual and their situatedness plays in the system. In this way, we will be closer to making a meaningful and authentic contribution to the advancement of knowledge, and not merely for the sake of renaming inventions.

Dissociation between exercise intensity thresholds: mechanistic insights from supine exercise

This study tested the hypothesis that the respiratory compensation point (RCP) and breakpoint in deoxygenated [heme] [deoxy[heme]_BP, assessed via near-infrared spectroscopy (NIRS)] during ramp incremental exercise would occur at the same metabolic rate in the upright (U) and supine (S) body positions. Eleven healthy men completed ramp incremental exercise tests in U and S. Gas exchange was measured breath-by-breath and time-resolved-NIRS was used to measure deoxy[heme] in the vastus lateralis (VL) and rectus femoris (RF). RCP (S: 2.56 ± 0.39, U: 2.86 ± 0.40 L·min^-1, P = 0.02) differed from deoxy[heme]_BP in the VL in U (3.10 ± 0.44 L·min^-1, P = 0.002), but was not different in S in the VL (2.70 ± 0.50 L·min^-1, P = 0.15). RCP was not different from the deoxy[heme]_BP in the RF for either position (S: 2.34 ± 0.48 L·min^-1, U: 2.76 ± 0.53 L·min^-1, P > 0.05). However, the deoxy[heme]_BP differed between muscles in both positions (P < 0.05), and changes in deoxy[heme]_BP did not relate to ΔRCP between positions (VL: r = 0.55, P = 0.080, RF: r = 0.26, P = 0.44). The deoxy[heme]_BP was consistently preceded by a breakpoint in total[heme], and was, in turn, itself preceded by a breakpoint in muscle surface electromyography (EMG). RCP and the deoxy[heme]_BP can be dissociated across muscles and different body positions and, therefore, do not represent the same underlying physiological phenomenon. The deoxy[heme]_BP may, however, be mechanistically related to breakpoints in total[heme] and muscle activity.

A Systems Analysis Critique of Sport-Science Research

PURPOSE

The broad aim of sport-science research is to enhance the performance of coaches and athletes. Despite decades of such research, it is well documented that sport-science research lacks empirical evidence, and critics have questioned its scientific methods. Moreover, many have pointed to a research-practice gap, whereby the work undertaken by researchers is not readily applied by practitioners. The aim of this study was to use a systems thinking analysis method, causal loop diagrams, to understand the systemic issues that interact to influence the quality of sport-science research.

METHODS

A group model-building process was utilized to develop the causal loop diagram based on data obtained from relevant peer-reviewed literature and subject-matter experts.

RESULTS

The findings demonstrate the panoply of systemic influences associated with sport-science research, including the existence of silos, a focus on quantitative research, archaic practices, and an academic system that is incongruous with what it actually purports to achieve.

CONCLUSIONS

The emergent outcome of the interacting components is the creation of an underperforming sport-science research system, as indicated by a lack of ecological validity, translation to practice, and, ultimately, a research-practice gap.

Dribble Deficit Enables Measurement of Dribbling Speed Independent of Sprinting Speed in Collegiate, Male, Basketball Players

ABSTRACT

Ramirez-Campillo, R, Gentil, P, Moran, J, Dalbo, VJ, and Scanlan, AT. Dribble Deficit enables measurement of dribbling speed independent of sprinting speed in collegiate, male, basketball players. J Strength Cond Res 35(7): 2040-2045, 2021-The aim of this study was to determine the relationships between sprinting and dribbling speed in basketball during linear and change-of-direction (COD) sprints using total dribbling time and Dribble Deficit. Collegiate, male, basketball players (n = 10; 21.0 ± 1.6 years) performed linear and COD sprints with and without dribbling a ball. Linear dribbling sprints were measured for the dominant and nondominant hands, whereas COD dribbling sprints involved bilateral use of hands. Dribble Deficit was determined as the difference between total time (second) during each dribbling trial and the equivalent nondribbling trial for linear and COD sprints. Simple linear regression analyses were performed during linear and COD sprints to determine the relationship (R) and shared variance (R2) between (a) sprinting times and total dribbling times and (b) sprinting times and Dribble Deficit. Large to very large, significant relationships were evident between linear sprinting and dribbling time for dominant (R = 0.86; R2 = 0.74, p = 0.001) and nondominant hands (R = 0.80; R2 = 0.65, p = 0.005). Trivial relationships were apparent between linear sprinting time and Dribble Deficit with dominant (R = 0.10; R2 = 0.01, p = 0.778) and nondominant hands (R = 0.03; R2 = 0.00, p = 0.940). A very large relationship was evident between COD sprinting and dribbling time (R = 0.91; R2 = 0.82, p < 0.001), whereas a trivial relationship was observed between COD sprinting time and COD Dribble Deficit (R = -0.23; R2 = 0.05, p = 0.530). Dribble Deficit eliminates the strong influence of sprinting speed on outcome measures typically seen when using tests predicated on total dribbling time. Consequently, Dribble Deficit may be of added use in basketball test batteries to measure dribbling speed across linear and multidirectional movement paths.

Health science knowledge translation: Critical appraisal of online physical activity promotion material

Limited research exists on how often health behavior theory concepts, principles, and techniques are embedded in the design of material to promote physical activity and exercise, such as persuasive communications disseminated via the Internet. This cross-sectional study examined 139 web articles on physical activity and exercise. We assessed how often article messages targeted recommended motivational determinants of health behavior: that is, outcome expectancy, self-efficacy, and self-regulation. Moreover, exploratory analyses were performed, which compared patterns in article messages by organization type. Results showed the largest categories were other messages and self-efficacy, each representing nearly one-third of article messages. The frequency that article messages targeted motivational determinants of physical activity and exercise differed by organization type. Our results suggest web articles that could promote physical activity and exercise motivation exist; however, they can be better constructed to meet the needs of people. For example, over half of article messages targeted a recommended motivational determinant, but the least targeted determinant was self-regulation. We present steps nurse educators and clinicians may take to improve the design or selection of physical activity and exercise promotion material.

Chronic resistance training: is it time to rethink the time course of neural contributions to strength gain?

Resistance training enhances muscular force due to a combination of neural plasticity and muscle hypertrophy. It has been well documented that the increase in strength over the first few weeks of resistance training (i.e. acute) has a strong underlying neural component and further enhancement in strength with long-term (i.e. chronic) resistance training is due to muscle hypertrophy. For obvious reasons, collecting long-term data on how chronic-resistance training affects the nervous system not feasible. As a result, the effect of chronic-resistance training on neural plasticity is less understood and has not received systematic exploration. Thus, the aim of this review is to provide rationale for investigating neural plasticity beyond acute-resistance training. We use cross-sectional work to highlight neural plasticity that occurs with chronic-resistance training at sites from the brain to spinal cord. Specifically, intra-cortical circuitry and the spinal motoneuron seem to be key sites for this plasticity. We then urge the need to further investigate the differential effects of acute versus chronic-resistance training on neural plasticity, and the role of this plasticity in increased strength. Such investigations may help in providing a clearer definition of the continuum of acute and chronic-resistance training, how the nervous system is altered during this continuum and the causative role of neural plasticity in changes in strength over the continuum of resistance training.

Effects of low-load blood flow restriction exercise to failure and non-failure on myoelectric activity: a meta-analysis

OBJECTIVES

To compare the short- and long-term effects of low load blood flow restriction (LL-BFR) versus low- (LL-RT) or high-load (HL-RT) resistance training with free blood flow on myoelectric activity, and investigate the differences between failure and non-failure protocols.

DATA SOURCE

We identified sources by searching the MEDLINE/PUBMED, CINAHL, WEB OF SCIENCE, CENTRAL, SCOPUS, SPORTDiscus, and PEDro electronic databases.

STUDY SELECTION

We screened titles and abstracts of 1048 articles using our inclusion criteria. A total of 39 articles were selected for further analysis.

DATA EXTRACTION

Two reviewers independently assessed the methodological quality of each study and extracted data from studies. A meta-analytic approach was used to compute standardized mean differences (SMD ± 95% confidence intervals (CI)). Subgroup analyses were conducted for both failure or non-failure protocols.

DATA SYNTHESIS

The search identified n = 39 articles that met the inclusion criteria. Regarding the short-term effects, LL-BFR increased muscle excitability compared with LL-RT during non-failure exercises (SMD 0.61, 95% CI 0.34 to 0.88), whereas HL-RT increased muscle excitability compared with LL-BFR regardless of voluntary failure (SMD -0.61, 95% CI -1.01 to 0.21) or not (SMD -1.13, CI -1.94 to -0.33). Concerning the long-term effects, LL-BFR increased muscle excitability compared with LL-RT during exercises performed to failure (SMD 1.09, CI 0.39 to 1.79).

CONCLUSIONS

Greater short-term muscle excitability levels are observed in LL-BFR than LL-RT during non-failure protocols. Conversely, greater muscle excitability is present during HL-RT compared with LL-BFR, regardless of volitional failure. Furthermore, LL-BFR performed to failure increases muscle excitability in the long-term compared with LL-RT.

Training Intensity Distribution, Training Volume, and Periodization Models in Elite Swimmers: A Systematic Review

A well-planned periodized approach allows swimmers to achieve peak performance at the major national and international competitions.

PURPOSE

To identify the main characteristics of endurance training for highly trained swimmers described by the training intensity distribution (TID), volume, and periodization models.

METHODS

The electronic databases Scopus, PubMed, and Web of Science were searched using a comprehensive list of relevant terms. Studies that investigated the effect of the periodization of training in swimming, with the training load (volume, TID) and periodization reported, were included in the systematic review.

RESULTS

A total of 3487 studies were identified, and after removal of duplicates and elimination of papers based on title and abstract screening, 17 articles remained.  A further 8 articles were excluded after full text review, leaving a final total of 9 studies in the systematic review. The evidence levels were 1b for intervention studies (n = 3) and 2b for (observational) retrospective studies (n = 6). The sprint swimmers typically followed a polarized and threshold TID, the middle-distance swimmers followed a threshold and pyramidal TID, and the long-distance swimmers primarily followed a pyramidal TID. The periodization model identified in the majority of studies selected is characterized by wave-like cycles in units like mesocycles to promote physiological adaptations and skill acquisition.

CONCLUSIONS

Highly trained swimmers follow a training volume and TID based on their primary event. There is a need for further experimental studies on the effects of block and reverse periodization models on swimming performance. Although observational studies of training have limited evidence, it is unclear whether a different training/periodization approach would yield better results.

Moving Sport and Exercise Science Forward: A Call for the Adoption of More Transparent Research Practices

The primary means of disseminating sport and exercise science research is currently through journal articles. However, not all studies, especially those with null findings, make it to formal publication. This publication bias towards positive findings may contribute to questionable research practices. Preregistration is a solution to prevent the publication of distorted evidence resulting from this system. This process asks authors to register their hypotheses and methods before data collection on a publicly available repository or by submitting a Registered Report. In the Registered Report format, authors submit a stage 1 manuscript to a participating journal that includes an introduction, methods, and any pilot data indicating the exploratory or confirmatory nature of the study. After a stage 1 peer review, the manuscript can then be offered in-principle acceptance, rejected, or sent back for revisions to improve the quality of the study. If accepted, the project is guaranteed publication, assuming the authors follow the data collection and analysis protocol. After data collection, authors re-submit a stage 2 manuscript that includes the results and discussion, and the study is evaluated on clarity and conformity with the planned analysis. In its final form, Registered Reports appear almost identical to a typical publication, but give readers confidence that the hypotheses and main analyses are less susceptible to bias from questionable research practices. From this perspective, we argue that inclusion of Registered Reports by researchers and journals will improve the transparency, replicability, and trust in sport and exercise science research. The preprint version of this work is available on SportR[Formula: see text]iv: https://osf.io/preprints/sportrxiv/fxe7a/.

A 4-Year Profile of Game Demands in Elite Women's Division I College Basketball

Ransdell, LB, Murray, T, Gao, Y, Jones, P, and Bycura, D. A 4-year profile of game demands in elite women's Division I college basketball. J Strength Cond Res 34(3): 632-638, 2020-Workload for a Division I women's collegiate basketball team (0.817 win percentage) was examined by: (a) season, (b) player position, and (c) game outcome (wins vs. losses). Female athletes (n = 6, mean 19.7 ± 1.5 years, at beginning of study) wore Catapult S5 units during 91.8% of games over a 4-year period. Average PlayerLoad, PlayerLoad per minute (PL·min), high inertial movement analysis (high-IMA), and jumps were quantified using Catapult Openfield software (version 1.14.1+). Data were checked for normality and log- or square-root-transformed when they were non-normal. A series of linear mixed model analyses were conducted to detect differences in PlayerLoad, PL·min, high-IMA, and jumps by season, position, and game outcome. PL·min and jumps data were not normal, so they were transformed, analyses were run; because there were no differences in findings, data are reported in original units to allow for comparisons with other studies. Cohen's d and confidence intervals were provided as additional information about the strength of reported differences. The 3 most consistent findings were that across a 4-year period, jumps increased, PL·min was higher in guards compared with posts, and high-IMA was higher in losses compared with wins. Other workload patterns were inconsistent, and inappropriate for making conclusive statements. Therefore, comparing jumps across multiple seasons, PL·min by player position and high-IMA in losses are important; in addition, all data can be used to profile National Collegiate Athletic Association Division I women's basketball players and set game workload expectations.

What influence does resistance exercise order have on muscular strength gains and muscle hypertrophy? A systematic review and meta-analysis

The objectives of this paper were to: (a) systematically review studies that explored the effects of exercise order (EO) on muscular strength and/or hypertrophy; (b) pool their results using a meta-analysis; and (c) provide recommendations for the prescription of EO in resistance training (RT) programmes. A literature search was performed in four databases. Studies were included if they explored the effects of EO on dynamic muscular strength and/or muscle hypertrophy. The meta-analysis was performed using a random-effects model with Hedges' g effect size (ES). The methodological quality of studies was appraised using the TESTEX checklist. Eleven good-to-excellent methodological quality studies were included in the review. When all strength tests, that is, both in multi-joint (MJ) and single-joint (SJ) exercises were considered, there was no difference between the EOs (ES = -0.11; p = 0.306). However, there was a difference between the MJ-to-SJ and SJ-to-MJ orders for strength gains in the MJ exercises, favouring starting the exercise session with MJ exercises (ES = 0.32; p = 0.034), and the strength gains in the SJ exercises, favouring starting the exercise session with SJ exercises (ES = -0.58; p = 0.032). No significant effect of EO was observed for hypertrophy combining site-specific and indirect measures (ES = 0.03; p = 0.862). In conclusion, increases in muscular strength are the largest in the exercises performed at the beginning of an exercise session. For muscle hypertrophy, our meta-analysis indicated that both MJ-to-SJ and SJ-to-MJ EOs may produce similar results.

Six Sessions of Sprint-Interval Training Did Not Improve Endurance and Neuromuscular Performance in Untrained Men

Previous research demonstrated that six sessions of cycling sprint-interval training (SIT) within a duration of only 2 weeks can increase endurance performance considerably. Primarily muscular mechanisms have been under investigation explaining such performance improvements. However, it has been shown in other exercise tasks that training-induced changes also occur at the level of the central nervous system. Therefore, we hypothesized to observe an enhanced neuromuscular performance in conjunction with an increase in endurance performance after 2 weeks of SIT. Therefore, we randomly assigned 19 healthy men (26 ± 5 years) to a control (n = 10) or a training group (n = 9), the latter performing a replication of the SIT protocol from Burgomaster et al. Before and after the training intervention, both groups performed a cycling endurance test until exhaustion. Neuromuscular function of the right vastus lateralis muscle was assessed before and after each endurance task by the means of maximal voluntary isometric contractions (MVCs). The variables of interest being MVC, voluntary activation was measured by peripheral nerve stimulations (VAPNS), by transcranial magnetic stimulation (VATMS), as well as potentiated resting twitches (Qtw,pot). We did not find any significant differences between the groups in the control variable time to exhaustion in the endurance task. In addition, we did not observe any time × group interaction effect in any of the neuromuscular parameters. However, we found a significant large-sized time effect in all neuromuscular variables (MVC, η p 2 = 0.181; VATMS, η p 2 = 0.250; VAPNS, η p 2 = 0.250; Qtw,pot, η p 2 = 0.304) as well as time to exhaustion η p 2 = 0.601). In contrast to other studies, we could not show that a short-term SIT is able to increase endurance performance. An unchanged endurance performance after training most likely explains the lack of differences in neuromuscular variables between groups. These findings demonstrate that replication studies are needed to verify results no matter how strong they seem to be. Differences over time for the variables of neuromuscular fatigue irrespective of group (MVC, + 9.3%; VATMS, + 0.2%; VAPNS, + 6.3%; Qtw,pot, + 6.3%) demonstrate test-retest effects that should be taken into consideration in future training studies and emphasize the inevitable necessity for controlled experiments.

Short-Term Training and Detraining Effects of Supervised vs. Unsupervised Resistance Exercise in Aging Adults

Orange, ST, Marshall, P, Madden, LA, and Vince, RV. Short-term training and detraining effects of supervised vs. unsupervised resistance exercise in aging adults. J Strength Cond Res 33(10): 2733-2742, 2019-This study compared the effects of a 4-week supervised (SUP) resistance training program and unsupervised (UNSUP) resistance training program followed by 12 weeks of detraining (DET). Thirty-six healthy aging adults (age: 53.6 ± 3.6 years; body mass index: 28.3 ± 5.1 kg·m) were randomly allocated to an SUP group (n = 17) or a UNSUP group (n = 19). Participants completed 3 training sessions per week using resistance bands and body weight movements. Measures of physical performance were administered at baseline, at the end of the training program, and after the DET period. Function was assessed with the 6-minute walk test (6MWT), timed up-and-go (TUG), 30-second chair sit-to-stand (STS), stair-climb test (SCT), 40-m fast-paced walk test (FPWT) and sit-and-reach test (SRT), whereas the isometric midthigh pull (IMTP) and hand grip test were used to measure muscle strength. After training, improvements in performance were found in the 6MWT, TUG, 30-second chair STS, SCT, FPWT, SRT, and IMTP (p ≤ 0.05), with no significant differences between groups (p > 0.05). In addition, most of the training-induced improvements remained significantly above baseline values after the DET period (p ≤ 0.05). No significant between-group differences were observed after training or DET (p > 0.05). Four weeks of either SUP or UNSUP resistance training is sufficient to substantially improve muscle strength and function in aging adults, and these gains are largely preserved after prescribed exercise cessation. Home-based resistance training seems to be a practical and effective alternative to traditional SUP programs that may help circumvent many barriers to physical activity in aging adults.

Resistance Training Volume Enhances Muscle Hypertrophy but Not Strength in Trained Men

Purpose

The purpose of this study was to evaluate muscular adaptations between low-, moderate-, and high-volume resistance training protocols in resistance-trained men.

Methods

Thirty-four healthy resistance-trained men were randomly assigned to one of three experimental groups: a low-volume group performing one set per exercise per training session (n = 11), a moderate-volume group performing three sets per exercise per training session (n = 12), or a high-volume group performing five sets per exercise per training session (n = 11). Training for all routines consisted of three weekly sessions performed on nonconsecutive days for 8 wk. Muscular strength was evaluated with one repetition maximum (RM) testing for the squat and bench press. Upper-body muscle endurance was evaluated using 50% of subjects bench press 1RM performed to momentary failure. Muscle hypertrophy was evaluated using B-mode ultrasonography for the elbow flexors, elbow extensors, mid-thigh, and lateral thigh.

Results

Results showed significant preintervention to postintervention increases in strength and endurance in all groups, with no significant between-group differences. Alternatively, while all groups increased muscle size in most of the measured sites from preintervention to postintervention, significant increases favoring the higher-volume conditions were seen for the elbow flexors, mid-thigh, and lateral thigh.

Conclusions

Marked increases in strength and endurance can be attained by resistance-trained individuals with just three 13-min weekly sessions over an 8-wk period, and these gains are similar to that achieved with a substantially greater time commitment. Alternatively, muscle hypertrophy follows a dose–response relationship, with increasingly greater gains achieved with higher training volumes.

The Speed of Neural Visual Motion Perception and Processing Determines the Visuomotor Reaction Time of Young Elite Table Tennis Athletes

Purpose: Recent research in adult badminton athletes has shown the visuomotor reaction time (VMRT) is strongly dependent on the speed of visual signal perception and processing in the brain's visual motion system. However, it remains unclear if this relation can be confirmed for other visuomotor demanding disciplines as well as different age groups. This study aimed to validate previous findings in international elite youth table tennis players to shed light on the generalizability of neural performance determinants across different visuomotor demanding sports and age groups. Methods: Thirty-seven young elite international table tennis players (18 male, 19 female, mean age: 13.5 years) from 23 nations participated in this study. Participants performed a visuomotor reaction task in response to visual motion stimuli presented at two different motion velocity conditions. Visuomotor performance was evaluated by measuring the electromyographic (EMG) onset as well as the VMRT. In addition, a 64-channel electroencephalography (EEG) system was used to investigate the stimulus and response-locked event-related potentials (ERPs) in the brain's visual motion sensitive area MT as well as the pre- and supplementary motor cortex indicating the speed of cortical visual and motor information processing, respectively. Correlation and multiple regression analyses identified the neural processes determining visuomotor performance. Results: The VMRT (232 vs. 258 ms, P < 0.001, d = -2.33) and EMG onset (181 vs. 206 ms, P < 0.001, d = -2.14) were accelerated in the fast motion velocity condition which was accompanied by an earlier stimulus-locked N2 (187 vs. 193 ms, P < 0.001, d = -0.80) and later response-locked N2-r (17 vs. -0.1 ms, P < 0.001, d = 1.04). The N2 and N2-r latencies were correlated with EMG onset and VMRT in both velocity conditions and explained between 80% and 90% of the variance in visuomotor reaction speed. Neural processes in BA6 did not differ between stimulus velocity conditions and did not contribute to the regression model. Conclusion: The results validate our previous findings and support the importance of neural visual processes for the visuomotor reaction speed across different visuomotor demanding sports and age groups. This suggests the visual system might be a promising target for specific visual diagnostics and training interventions.

The Speed of Neural Visual Motion Perception and Processing Determines the Visuomotor Reaction Time of Young Elite Table Tennis Athletes

Purpose: Recent research in adult badminton athletes has shown the visuomotor reaction time (VMRT) is strongly dependent on the speed of visual signal perception and processing in the brain’s visual motion system. However, it remains unclear if this relation can be confirmed for other visuomotor demanding disciplines as well as different age groups. This study aimed to validate previous findings in international elite youth table tennis players to shed light on the generalizability of neural performance determinants across different visuomotor demanding sports and age groups.

Methods: Thirty-seven young elite international table tennis players (18 male, 19 female, mean age: 13.5 years) from 23 nations participated in this study. Participants performed a visuomotor reaction task in response to visual motion stimuli presented at two different motion velocity conditions. Visuomotor performance was evaluated by measuring the electromyographic (EMG) onset as well as the VMRT. In addition, a 64-channel electroencephalography (EEG) system was used to investigate the stimulus and response-locked event-related potentials (ERPs) in the brain’s visual motion sensitive area MT as well as the pre- and supplementary motor cortex indicating the speed of cortical visual and motor information processing, respectively. Correlation and multiple regression analyses identified the neural processes determining visuomotor performance.

Results: The VMRT (232 vs. 258 ms, P < 0.001, d = −2.33) and EMG onset (181 vs. 206 ms, P < 0.001, d = −2.14) were accelerated in the fast motion velocity condition which was accompanied by an earlier stimulus-locked N2 (187 vs. 193 ms, P < 0.001, d = −0.80) and later response-locked N2-r (17 vs. −0.1 ms, P < 0.001, d = 1.04). The N2 and N2-r latencies were correlated with EMG onset and VMRT in both velocity conditions and explained between 80% and 90% of the variance in visuomotor reaction speed. Neural processes in BA6 did not differ between stimulus velocity conditions and did not contribute to the regression model.

Conclusion: The results validate our previous findings and support the importance of neural visual processes for the visuomotor reaction speed across different visuomotor demanding sports and age groups. This suggests the visual system might be a promising target for specific visual diagnostics and training interventions.

Screen Recordings as a Tool to Document Computer Assisted Data Collection Procedures

Recently in psychological science and many related fields, a surprisingly large amount of experiments could not be replicated by independent researchers. A non-replication could indicate that a previous finding might have been a false positive statistical result and the effect does not exist. However, it could also mean that a specific detail of the experimental procedure is essential for the effect to emerge, which might not have been included in the replication attempt. Therefore any replication attempt that does not replicate the original effect is most informative when the original procedure is closely adhered to. One proposed solution to facilitate the empirical reproducibility of the experimental procedures in psychology is to upload the experimental script and materials to a public repository. However, we believe that merely providing the materials of an experimental procedure is not sufficient, as many software solutions are not freely available, software solutions might change, and it is time consuming to set up the procedure. We argue that there is a simple solution to these problems when an experiment is conducted using computers: recording an example procedure with a screen capture software and providing the video in an online repository. We therefore provide a brief tutorial on screen recordings using an open source screen recording software. With this information, individual researchers should be able to record their experimental procedures and we hope to facilitate the use of screen recordings in computer assisted data collection procedures.

Dynamic stretching alone can impair slower velocity isokinetic performance of young male handball players for at least 24 hours

There are many adult studies reporting static stretch (SS)-induced deficits and dynamic stretch (DS) performance improvements shortly after the intervention. However, there is only a single study examining stretch-induced performance changes with youth at 24 hours' post-stretch. The objective of this study was to examine physiological responses of young trained athletes at 24-hours after experiencing SS or DS protocols. Eight young male, elite handball players (age: 16.1±5.1 years) were tested prior to-, 3-minutes and 24-hours following the three conditions (DS, SS, Control) in a randomized and counterbalanced order. Similar volumes of SS (2 repetitions of 75s for each leg) and DS (5 repetitions of 30s for each leg) involved one stretch each for the quadriceps and hamstrings. Tests included (i) two 4s maximal voluntary isometric contractions (MVC) at 60° of knee flexion with 2-min rest, (ii) two maximal isokinetic contractions each at 60°/sec and 300°/sec with 1-min rest, and (iii) two drop jumps with 30-sec rest. To simulate a full warm-up, dynamic activity including 5 minutes of aerobic cycling (70 rpm; 1 kilopond), 4 submaximal isometric contractions and 4 drop jumps were instituted before the pre-tests and following the interventions. Two-way repeated measures ANOVAs revealed that 1) both the SS and control conditions exhibited knee extensor 60°.s-1 (SS:-10.3%; p = 0.04, Control: -8.7%; p = 0.07) and 300°.s-1 (SS: -12.9%; p = 0.005, Control: -16.3%; p = 0.02) isokinetic deficits at post-test, 2) DS impaired knee flexor 60°.s-1 isokinetic work and power-related measures at post-test (Work: -10.1%; p = 0.0006; Power: -19.1%; p = 0.08) and at 24-hours' post-test (Work: 9.9%; p = 0.023; Power: -9.6%; p = 0.01), 3) DS (12.07% and 10.47%) and SS (13.7% and 14.6%) enhanced knee flexor 300°.s-1 isokinetic force and power-related measures compared to control. In conclusion, testing-induced knee extensor isokinetic impairments were counterbalanced by DS, however the hip flexion DS could have produced minor muscle damage for at least 24-hours decreasing knee flexor forces and power at 60°.s-1.

Dominant and nondominant leg press training induce similar contralateral and ipsilateral limb training adaptations with children

Cross-education has been extensively investigated with adults. Adult studies report asymmetrical cross-education adaptations predominately after dominant limb training. The objective of the study was to examine unilateral leg press (LP) training of the dominant or nondominant leg on contralateral and ipsilateral strength and balance measures. Forty-two youth (10-13 years) were placed (random allocation) into a dominant (n = 15) or nondominant (n = 14) leg press training group or nontraining control (n = 13). Experimental groups trained 3 times per week for 8 weeks and were tested pre-/post-training for ipsilateral and contralateral 1-repetition maximum (RM) horizontal LP, maximum voluntary isometric contraction (MVIC) of knee extensors (KE) and flexors (KF), countermovement jump (CMJ), triple hop test (THT), MVIC strength of elbow flexors (EF) and handgrip, as well as the stork and Y balance tests. Both dominant and nondominant LP training significantly (p < 0.05) increased both ipsilateral and contralateral lower body strength (LP 1RM (dominant: 59.6%-81.8%; nondominant: 59.5%-96.3%), KE MVIC (dominant: 12.4%-18.3%; nondominant: 8.6%-18.6%), KF MVIC (dominant: 7.9%-22.3%; nondominant: nonsignificant-3.8%), and power (CMJ: dominant: 11.1%-18.1%; nondominant: 7.7%-16.6%)). The exception was that nondominant LP training demonstrated a nonsignificant change with the contralateral KF MVIC. Other significant improvements were with nondominant LP training on ipsilateral EF 1RM (6.2%) and THT (9.6%). There were no significant changes with EF and handgrip MVIC. The contralateral leg stork balance test was impaired following dominant LP training. KF MVIC exhibited the only significant relative post-training to pretraining (post-test/pre-test) ratio differences between dominant versus nondominant LP cross-education training effects. In conclusion, children exhibit symmetrical cross-education or global training adaptations with unilateral training of dominant or nondominant upper leg.

Towards Subject-Specific Strength Training Design through Predictive Use of Musculoskeletal Models

Lower extremity dysfunction is often associated with hip muscle strength deficiencies. Detailed knowledge of the muscle forces generated in the hip under specific external loading conditions enables specific structures to be trained. The aim of this study was to find the most effective movement type and loading direction to enable the training of specific parts of the hip muscles using a standing posture and a pulley system. In a novel approach to release the predictive power of musculoskeletal modelling techniques based on inverse dynamics, flexion/extension and ab-/adduction movements were virtually created. To demonstrate the effectiveness of this approach, three hip orientations and an external loading force that was systematically rotated around the body were simulated using a state-of-the art OpenSim model in order to establish ideal designs for training of the anterior and posterior parts of the M. gluteus medius (GM). The external force direction as well as the hip orientation greatly influenced the muscle forces in the different parts of the GM. No setting was found for simultaneous training of the anterior and posterior parts with a muscle force higher than 50% of the maximum. Importantly, this study has demonstrated the use of musculoskeletal models as an approach to predict muscle force variations for different strength and rehabilitation exercise variations.

Interpreting Signal Amplitudes in Surface Electromyography Studies in Sport and Rehabilitation Sciences

Surface electromyography (sEMG) is a popular research tool in sport and rehabilitation sciences. Common study designs include the comparison of sEMG amplitudes collected from different muscles as participants perform various exercises and techniques under different loads. Based on such comparisons, researchers attempt to draw conclusions concerning the neuro- and electrophysiological underpinning of force production and hypothesize about possible longitudinal adaptations, such as strength and hypertrophy. However, such conclusions are frequently unsubstantiated and unwarranted. Hence, the goal of this review is to discuss what can and cannot be inferred from comparative research designs as it pertains to both the acute and longitudinal outcomes. General methodological recommendations are made, gaps in the literature are identified, and lines for future research to help improve the applicability of sEMG are suggested.