Eight-Week Flywheel Training Enhances Jump Performance and Stretch-Shortening Cycle Function in Collegiate Basketball Players

The effects of flywheel (FW) training on jump performance, muscle function, and muscle mass in athletes have not been fully clarified. The purpose of the present study was to evaluate the effects of an 8-week FW training program on jump performance, stretch-shortening cycle (SSC) function, muscle strength, peak power and muscle thickness in collegiate basketball players. Twenty male college basketball players (mean age: 19.8 ± 1.3 years, height: 179.1 ± 6.7 cm, body mass: 72.9 ± 6.3 kg) were randomly assigned to either the FW training (n = 11) or control group (n = 9). The FW training group performed squat exercises, 5 sets of 8 repetitions, twice a week using the FW device. Baseline and post-training assessments of jump heights of squat jumps (SJs), countermovement jumps (CMJs), and drop jumps (DJs) were performed in both groups. Additionally, the reactive strength index (RSI), representing SSC function; isometric maximum voluntary contraction (MVC) torque during knee joint extension; peak power during squats; and quadriceps muscle thickness were evaluated. As the results, we observed that the FW training group demonstrated significant increases in post-training SJ height (15.1%, p = 0.03), DJ height (23.2%, p = 0.01), RSI (36.8%, p = 0.04), MVC, peak power and muscle thickness compared with pre-training levels. Furthermore, between-group comparisons indicated significantly higher post-training SJ height, DJ height, RSI, MVC, peak power, and muscle thickness in the FW training group (p < 0.05). Therefore, the FW training program effectively enhanced jump performance and SSC function in male basketball players and proved beneficial for muscle strength and hypertrophy.

Efficacy of a physical rehabilitation program using virtual reality in patients with chronic tendinopathy: A randomized controlled trial protocol (VirTendon-Rehab)

Objectives

To analyze the efficacy of a virtual reality (VR)-based rehabilitation program in people with chronic tendinopathy (CT) on pain, muscle activation pattern, range of motion, muscle strength, kinesiophobia, physical function, quality of life, and user satisfaction compared to a control group. In addition, the relationship between these variables and the clinical profile of this population will be analyzed.

Design

A 12-week, single-blind, low-risk, randomized controlled trial.

Methods

Sixty patients diagnosed with CT will be enrolled and randomly assigned to two groups. The control group will receive a physical exercise program without VR support (45 min), whereas the experimental group will receive an additional 15-min intervention through a physical exercise program delivered by VR. Both groups will receive three sessions per week, and the outcomes will be collected at baseline, after 12 weeks, and at the 24-week follow-up. Stratified groups will be established according to tendinopathy location (shoulder rotator cuff, elbow, patella, and Achilles tendon). Statistical analyses using SPSS v.24 will include descriptive analysis, stratified analysis by tendinopathy location, normality checks, intragroup and intergroup differences, effect sizes, and variable relationships.

Discussion

The results of this project may have a significant impact on the knowledge of using VR in tendinopathy management, understanding how the outcomes are related, and characterizing the clinical profiles of the population diagnosed with CT. If these results are confirmed, VR would be clinically useful for the treatment of these conditions.

Trial registration number

NCT06056440.

Mixed comparison of intervention with eccentric, isometric, and heavy slow resistance for Victorian Institute of Sport Assessment Patella Questionnaire in adults with patellar tendinopathy: A systematic review and network meta-analysis

Background

PT (Patellar Tendinopathy) is a degenerative disorder of the tendons induced via extended overstretching or overuse of the tendons instead than usual inflammation. In the past, humans have centered on a number of strategies of treating PT such as ultrasound and surgical treatment. However, they did no longer genuinely consider the effectiveness of eccentric, isometric, or HSR (Heavy Slow Resistance Training) education for PT; They did now not really outline the stage of PT to beautify the uniformity of the find out about participants; They did no longer immediately examine the affects of isometric, eccentric, and HSR training. This systematic assessment chosen eccentric, isometric, and heavy gradual resistance coaching for the remedy of patellar tendinopathy and their respective prognostic effects will supply valuable, top notch evidence-based insights as properly as vital facts and advice for future scientific administration of patellar tendinopathy.

Methods

A thorough and comprehensive search was conducted across the Web of Science, PubMed, and Scopus databases, encompassing a wide range of relevant journals and sources, in order to perform a rigorous systematic review and network meta-analysis, ensuring the inclusion of all pertinent and high-quality studies. The selected studies satisfied predetermined eligibility requirements, which included: (1) PT patients included in the studies; (2) use of eccentric, isometric, and heavy slow resistance training as interventions; and (3) evaluation of VISA-P (Victorian Institute of Sport Assessment Patella Questionnaire) outcome measures. The effect magnitude was measured using the standard mean difference. The risk of bias inherent in each of the studies that were meticulously selected and included in the comprehensive analysis was rigorously evaluated and assessed using the well-established Cochrane Collaboration Risk of Bias Assessment Tool, ensuring the robustness and reliability of the research findings.

Results

Three scientific databases yielded a total of 1460 studies, of which 7 were included in the final analysis. The findings indicated that eccentric training (0.01 in Rank 1 and 0.06 in Rank 8) is the worst method for increasing VISA-P level in patients with patellar tendinopathy, while moderate resistance slow training (0.25) and Rank 1 and Rank 8 are the best options.

Conclusions

While heavy slow resistance is more suited for attaining long-term improvements in knee function, progressive tendon-loading exercises combined with isometric training or moderate slow resistance training are more beneficial than eccentric training alone. Eccentric training gives a greater range of exercise venues and doesn't require any additional training equipment. The inability to directly compare the effects of heavy slow, eccentric, and isometric resistance training constitutes a significant drawback of this review. This limitation stems from the scarcity of research that compares the outcomes of these various therapeutic approaches. To address this constraint, future research endeavors should strive to conduct comparative studies of these strategies. By doing so, they can aim to bridge this evaluation gap and facilitate a more effective and comprehensive assessment of their respective efficacies.

Effects of low-load blood flow restriction training in healthy adult tendons: A systematic review and meta-analysis

OBJECTIVE

To systematically review the effects of low-load blood flow restriction training (LL-BFR) on healthy adult tendons.

DESIGN

A systematic review with meta-analysis.

LITERATURE SEARCH

Six electronic databases were searched by two researchers.

STUDY SELECTION CRITERIA

Clinical trials comparing the effects of LL-BFR to high-load resistance training (HL-RT) or low-load resistance training (LL-RT) in healthy adult tendons.

DATA SYNTHESIS

Two reviewers selected the eligible clinical trials, and one reviewer exported the data. Two reviewers evaluated the study quality and risk of bias using the PEDro scale and the ROB2 scale. We performed meta-analysis where appropriate using a random-effects model. We rated the quality of evidence using GRADE.

RESULTS

Six studies were eligible. We analyzed tendon cross-sectional area (CSA) and tendon stiffness as the outcomes. Across all comparisons, there was low-to moderate-quality evidence of a difference between LL-BFR and LL-RT immediately after exercise. There was high-quality evidence of no difference between LL-BFR and HL-RT in the long term.

CONCLUSION

The effects of LL-BFR on the tendons depends on the time and dose of the intervention. LL-BFR could be useful to increase the CSA of the tendons in a similar or superior way to HL-RT after 8 weeks of intervention.

Current Guidelines for the Implementation of Flywheel Resistance Training Technology in Sports: A Consensus Statement

BACKGROUND

Flywheel resistance training has become more integrated within resistance training programs in a variety of sports due to the neuromuscular, strength, and task-specific enhancements reported with this training.

OBJECTIVE

This paper aimed to present the consensus reached by internationally recognized experts during a meeting on current definitions and guidelines for the implementation of flywheel resistance training technology in sports.

METHODS

Nineteen experts from different countries took part in the consensus process; 16 of them were present at the consensus meeting (18 May 2023) while three submitted their recommendations by e-mail. Prior to the meeting, evidence summaries were developed relating to areas of priority. This paper discusses the available evidence and consensus process from which recommendations were made regarding the appropriate use of flywheel resistance training technology in sports. The process to gain consensus had five steps: (1) performing a systematic review of systematic reviews, (2) updating the most recent umbrella review published on this topic, (3) first round discussion among a sample of the research group included in this consensus statement, (4) selection of research group members-process of the consensus meeting and formulation of the recommendations, and (5) the consensus process. The systematic analysis of the literature was performed to select the most up-to-date review papers available on the topic, which resulted in nine articles; their methodological quality was assessed according to AMSTAR 2 (Assessing the Methodological Quality of Systematic Review 2) and GRADE (Grading Recommendations Assessment Development and Evaluation). Statements and recommendations scoring 7-9 were considered appropriate.

RESULTS

The recommendations were based on the evidence summary and researchers' expertise; the consensus statement included three statements and seven recommendations for the use of flywheel resistance training technology. These statements and recommendations were anonymously voted on and qualitatively analyzed. The three statements reported a score ranging from 8.1 to 8.8, and therefore, all statements included in this consensus were considered appropriate. The recommendations (1-7) had a score ranging from 7.7 to 8.6, and therefore, all recommendations were considered appropriate.

CONCLUSIONS

Because of the consensus achieved among the experts in this project, it is suggested that practitioners and researchers should adopt the guidelines reported in this consensus statement regarding the use of flywheel resistance technology in sports.

Exercise therapy for tendinopathy: a mixed-methods evidence synthesis exploring feasibility, acceptability and effectiveness

Background

Tendinopathy is a common, painful and functionally limiting condition, primarily managed conservatively using exercise therapy.

Review questions

(i) What exercise interventions have been reported in the literature for which tendinopathies? (ii) What outcomes have been reported in studies investigating exercise interventions for tendinopathy? (iii) Which exercise interventions are most effective across all tendinopathies? (iv) Does type/location of tendinopathy or other specific covariates affect which are the most effective exercise therapies? (v) How feasible and acceptable are exercise interventions for tendinopathies?

Methods

A scoping review mapped exercise interventions for tendinopathies and outcomes reported to date (questions i and ii). Thereafter, two contingent systematic review workstreams were conducted. The first investigated a large number of studies and was split into three efficacy reviews that quantified and compared efficacy across different interventions (question iii), and investigated the influence of a range of potential moderators (question iv). The second was a convergent segregated mixed-method review (question v). Searches for studies published from 1998 were conducted in library databases (n = 9), trial registries (n = 6), grey literature databases (n = 5) and Google Scholar. Scoping review searches were completed on 28 April 2020 with efficacy and mixed-method search updates conducted on 19 January 2021 and 29 March 2021.

Results

Scoping review - 555 included studies identified a range of exercise interventions and outcomes across a range of tendinopathies, most commonly Achilles, patellar, lateral elbow and rotator cuff-related shoulder pain. Strengthening exercise was most common, with flexibility exercise used primarily in the upper limb. Disability was the most common outcome measured in Achilles, patellar and rotator cuff-related shoulder pain; physical function capacity was most common in lateral elbow tendinopathy. Efficacy reviews - 204 studies provided evidence that exercise therapy is safe and beneficial, and that patients are generally satisfied with treatment outcome and perceive the improvement to be substantial. In the context of generally low and very low-quality evidence, results identified that: (1) the shoulder may benefit more from flexibility (effect sizeResistance:Flexibility = 0.18 [95% CrI 0.07 to 0.29]) and proprioception (effect sizeResistance:Proprioception = 0.16 [95% CrI -1.8 to 0.32]); (2) when performing strengthening exercise it may be most beneficial to combine concentric and eccentric modes (effect sizeEccentricOnly:Concentric+Eccentric = 0.48 [95% CrI -0.13 to 1.1]; and (3) exercise may be most beneficial when combined with another conservative modality (e.g. injection or electro-therapy increasing effect size by ≈0.1 to 0.3). Mixed-method review - 94 studies (11 qualitative) provided evidence that exercise interventions for tendinopathy can largely be considered feasible and acceptable, and that several important factors should be considered when prescribing exercise for tendinopathy, including an awareness of potential barriers to and facilitators of engaging with exercise, patients' and providers' prior experience and beliefs, and the importance of patient education, self-management and the patient-healthcare professional relationship.

Limitations

Despite a large body of literature on exercise for tendinopathy, there are methodological and reporting limitations that influenced the recommendations that could be made.

Conclusion

The findings provide some support for the use of exercise combined with another conservative modality; flexibility and proprioception exercise for the shoulder; and a combination of eccentric and concentric strengthening exercise across tendinopathies. However, the findings must be interpreted within the context of the quality of the available evidence.

Future work

There is an urgent need for high-quality efficacy, effectiveness, cost-effectiveness and qualitative research that is adequately reported, using common terminology, definitions and outcomes.

Study registration

This project is registered as DOI: 10.11124/JBIES-20-00175 (scoping review); PROSPERO CRD 42020168187 (efficacy reviews); https://osf.io/preprints/sportrxiv/y7sk6/ (efficacy review 1); https://osf.io/preprints/sportrxiv/eyxgk/ (efficacy review 2); https://osf.io/preprints/sportrxiv/mx5pv/ (efficacy review 3); PROSPERO CRD42020164641 (mixed-method review).

Funding

This project was funded by the National Institute for Health and Care Research (NIHR) HTA programme and will be published in full in HTA Journal; Vol. 27, No. 24. See the NIHR Journals Library website for further project information.

Stojanović MD, Bird SP, Calleja-González J. Effectiveness of Eccentric Overload Training in Basketball Players: A Systematic Review

Several studies have confirmed the efficacy of flywheel eccentric overload training in order to improve or increase muscle volume and strength, as well as several performance-related fitness attributes, but to date, there are no studies that have reviewed the effects of these training methods in basketball. Therefore, the present systematic review aimed to collect the updated information about the influence of flywheel training on performance of basketball players. A search in four electronic databases (PubMed, SCOPUS, Web of Science, and Google Scholar) was conducted up to November 20, 2022. Articles were selected as valid for review if: (i) they were an experimental trial published in English; (ii) participants were basketball players without illnesses or injuries, and (iii) a rotational inertial overload method was used as a performance-dependent variable. A total of 93 articles were found. After filtering procedures, only seven studies were considered in this systematic review. In the selected studies, 203 participants were included, 58 females and 145 males. Focusing on basketball related performance variables, all the studies included the countermovement jump (CMJ), while five included sprinting and a change of direction test (COD). The results showed an improvement in performance-related variables associated with basketball (sprint, CMJ, and COD) through the use of inertial methods. Improvements were reported in professional, semi-professional and amateur players as well as both male and female players. However, given the low number of studies, additional investigations on this topic are warranted before a "clear picture" can be drawn concerning the effects of flywheel eccentric overload training in basketball players.

Are Current Prophylactic Programs Effective in Preventing Patellar Tendinopathy in Athletes and Recruits? A Meta-Analysis and Trial Sequential Analysis

CONTEXT

Patellar tendinopathy (PT), or jumper's knee, is a chronic painful overuse patellar tendon injury. For PT, prevention is more important than treatment. However, there is still a lack of strong evidence to confirm the effectiveness of prevention.

OBJECTIVE

This study will analyze by meta-analysis the effect of a prophylactic program on high PT risk people (but without PT) in reducing PT occurrence.

DATA SOURCES

PubMed, Embase, the Cochrane Library, Scopus, and Ebscohost, from inception to January 11, 2022.

STUDY SELECTION

A study comparing the effects of prophylactic programs and controls on the risk of PT was included in the analysis. After a database search with search terms ((patellar tendinopathy) OR (jumper's knee) OR (patellar tendinitis) OR (patellar tendinosis) OR (patellar tendonitis)) AND ((Prevent*) OR (prophyla*)), a total of 1444 items were obtained. Of these, 11 studies with 6091 participants were eligible for inclusion in this meta-analysis.

STUDY DESIGN

Systematic review and meta-analysis.

LEVEL OF EVIDENCE

Level 2.

DATA EXTRACTION

The first author's name, publication year, study design, country, population, mean age, sex, prophylactic program, control, study duration, and the frequency or incidence of PT in each group were extracted.

RESULTS

A total of 11 articles were included in the analysis. Overall, no significant difference was considered in the risk of PT between the prophylactic program and control groups based on the random-effect model (odds ratio [OR], 0.85; 95% CI, 0.67, 1.08; P = 0.18). In the recruit subgroup, there was even a tendency to elevate the risk of PT occurrence after prophylaxis was executed (OR, 1.89; 95% CI, 0.68, 5.28; P = 0.22). In athletes, the prophylactic program tended to decrease the risk of PT compared with the control (OR, 0.81; 95% CI, 0.63, 1.04; P = 0.10); however, the difference was not statistically significant. Trial sequential analysis results suggested that prophylaxis may still be effective for athletes, but this needs to be confirmed with a larger sample size.

CONCLUSION

The risk of PT cannot be reduced with the current prophylactic program. However, for athletes, the negative results may be due to insufficient sample size.

Perception and use of flywheel resistance training amongst therapists in sport

Flywheel (isoinertial) resistance training is a valid strength training method that has been incorporated in sport for decades, yet little is known about how therapists working in sport apply flywheel resistance training. We aimed to describe and understand current application and perception of flywheel resistance training amongst therapists working in sport. Seventy- three therapists (13 ± 10 years of experience) started part of this survey with 52 completing the entire electronic questionnaire. Nine multiple choice questions on application and perceptions of flywheel training (prerequisites, use of technology, barriers, and upper- and lower-body exercises) preceded two 6-point Likert scale statements on strength and reduction of injury likelihood. Most therapists (47/73) either used or intended to use flywheel training with their athletes and stated familiarisation would be a priority prior to initiating training. Although more than half suggested they were confident flywheel training could enhance strength (27/52) and muscular prehabilitation outcomes (40/52), many remained unsure. Nonetheless, it appears that therapists would mostly include flywheel training within prehabilitation (40/52) or during the later stages of rehabilitation (37/52). To monitor progress, therapists slightly prefer power (30/52) over velocity outputs, while few would not use them at all. Although therapists would prescribe most exercises - the squat, rotational exercise, and unilateral leg curl would be the most selected. Meanwhile, therapists reported remain most unsure or would avoid prescribing the lateral squat and unilateral hip extension. The biggest perceived barriers to flywheel training are equipment cost/space, evidence, and scheduling. The investigation provides valuable insight into the application and perception of flywheel training amongst therapists working in sport.

Inertial Flywheel Resistance Training in Tendinopathy Rehabilitation: A Scoping Review

Background

Inertial Flywheel Resistance Training (IFRT) has recently emerged as a beneficial rehabilitation option for some musculoskeletal disorders. Although the use of resistance training as treatment for tendinopathy has become widespread, it is unclear if IFRT has efficacy as a treatment option for tendinopathies.

Objective

To identify current evidence on IFRT in the treatment of tendinopathy, evaluating intervention parameters and outcomes.

Methods

This scoping review was reported in accordance with the PRISMA Extension for Scoping Reviews (PRISMA-ScR). Databases searched included MEDLINE, CINAHL, AMED, EMBase, SPORTDiscus, Cochrane library (Controlled trials, Systematic reviews), and five trial registries. Two independent reviewers screened studies at title, abstract and full text. Following screening, data were extracted and charted, and presented as figures and tables alongside a narrative synthesis. Any study design conducted on adults, investigating the effects of IFRT for tendinopathy were included. Data were extracted on intervention parameters and outcomes of IFRT interventions.

Results

Four studies on patellar tendinopathy were included. A variety of outcomes were assessed, including pain, function, strength, power, and tendon morphological and mechanical properties, particularly changes in tendon thickness. IFRT intervention parameters were largely homogenously prescribed, with slight variances.

Conclusion

Despite a paucity of studies to date on the effects of IFRT for treating tendinopathy, preliminary evidence for beneficial effects of IFRT on clinical outcomes in patellar tendinopathy is encouraging. As IFRT is a relatively new and unexplored method in tendinopathy rehabilitation, definitive conclusions, and recommendations cannot be made at present, which should be addressed in future research, due to the potential therapeutic benefits highlighted in this review.

A comparative study of treatment interventions for patellar tendinopathy: a secondary cost-effectiveness analysis

OBJECTIVE

To compare the cost-effectiveness of three patellar tendinopathy treatments.

DESIGN

Secondary (cost-effectiveness) analysis of a blinded, randomised controlled trial, with follow-up at 10 and 22 weeks.

SETTINGS

Recruitment was performed in sport clubs. The diagnosis and the intervention were carried out at San Jorge University.

PARTICIPANTS

The participants were adults between 18 and 45 years (n = 48) with patellar tendinopathy.

INTERVENTIONS

Participants received percutaneous needle electrolysis, dry needling or sham needling, all of which were combined with eccentric exercise.

MAIN OUTCOME MEASURES

Costs, quality-adjusted life years and incremental cost-effectiveness ratio were calculated for each group.

RESULTS

The total cost per session was similar in the three groups: €9.46 for the percutaneous needle electrolysis group; €9.44 for the dry needling group; and €8.96 for the sham group. The percutaneous needle electrolysis group presented better cost-effectiveness in terms of quality-adjusted life years and 96% and 93% probability of being cost-effective compared to the sham and dry needling groups, respectively.

CONCLUSION

Our study shows that percutaneous needle electrolysis has a greater probability of being cost-effective than sham or dry needling treatment.

Interventions for prevention and in-season management of patellar tendinopathy in athletes: A scoping review

INTRODUCTION

Patellar tendinopathy (PT) has a high prevalence in jumping athletes and presents a significant burden on athletes and clinicians due to its long-lasting duration and persistent symptoms. This scoping review aimed to map existing evidence on prevention and in-season management interventions for PT in athletes, evaluating intervention parameters and outcomes.

METHODS

This scoping review was reported in accordance with the PRISMA-ScR. Databases searched included MEDLINE, CINAHL, AMED, EMBase, SPORTDiscus, and the Cochrane library (Controlled trials, Systematic reviews). All primary study designs investigating prevention or in-season management interventions for PT, while maintaining athletes in sport were considered for inclusion.

RESULTS

5987 articles were identified with 29 included in the review. Five studies investigated exercise-based prevention interventions on athletes at risk for PT, including two randomized controlled trials (RCTs), two cohort studies and one case-control study. 24 studies investigated in-season management or rehabilitation in athletes with PT, including 18 RCTs, three case reports, one cohort study, one case series, and one retrospective review. Of these 24 studies, 22 used various resistance training interventions, one used ESWT and one used patellar strapping and taping. The types of resistance training included eccentric, heavy-slow, isometric, inertial flywheel, blood-flow restriction, and isotonic training. Eccentric training was used in 9 studies, with single leg decline squats the most common exercise used in 7 studies. Outcome measures and intervention parameters were heterogenous throughout studies.

CONCLUSION

Despite a dearth of studies on preventative interventions for athletes with PT, resistance training may be a useful prophylactic method. Eccentric, heavy slow and isometric resistance training have been found to be feasible and clinically beneficial in-season. There are a lack of studies showing that ESWT offers any additional benefit over resistance training in competing athletes. Patellar strapping and taping may offer short-term pain relief during training and competition. Systematic reviews are required to make definitive recommendations for PT.

The effect of flywheel training on strength and physical capacities in sporting and healthy populations: An umbrella review

The aim of this umbrella review was to provide a detailed summary of how flywheel training enhances strength and physical capacities in healthy and athletic populations. The eleven reviews included were analyzed for methodological quality according to the Assessing the Methodological Quality of Systematic Review 2 (AMSTAR 2) and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. Two were systematic reviews, six were systematic reviews with meta-analyses and three were narrative reviews. Although the included reviews support use of flywheel training with athletic and healthy populations, the umbrella review highlights disparity in methodological quality and over-reporting of studies (38 studies were included overall). Flywheel post-activation performance enhancement protocols can effectively enhance strength and physical capacities acutely with athletes and healthy populations. All relevant reviews support flywheel training as a valid alternative to traditional resistance training for enhancing muscular strength, power, and jump performance with untrained and trained populations alike. Similarly, reviews included report flywheel training enhances change of direction performance-although conclusions are based on a limited number of investigations. However, the reviews investigating the effect of flywheel training on sprint performance highlight some inconsistency in attained improvements with elite athletes (e.g., soccer players). To optimize training outcomes, it is recommended practitioners individualize (i.e., create inertia-power or inertia-velocity profiles) and periodize flywheel training using the latest guidelines. This umbrella review provides an analysis of the literature's strengths and limitations, creating a clear scope for future investigations.

Simplifying External Load Data in NCAA Division-I Men's Basketball Competitions: A Principal Component Analysis

The primary purpose was to simplify external load data obtained during Division-I (DI) basketball competitions via principal component analysis (PCA). A secondary purpose was to determine if the PCA results were sensitive to load demands of different positional groups (POS). Data comprised 229 observations obtained from 10 men's basketball athletes participating in NCAA DI competitions. Each athlete donned an inertial measurement unit that was affixed to the same location on their shorts prior to competition. The PCA revealed two factors that possessed eigenvalues >1.0 and explained 81.42% of the total variance. The first factor comprised total decelerations (totDEC, 0.94), average speed (avgSPD, 0.90), total accelerations (totACC, 0.85), total mechanical load (totMECH, 0.84), and total jump load (totJUMP, 0.78). Maximum speed (maxSPD, 0.94) was the lone contributor to the second factor. Based on the PCA, external load variables were included in a multinomial logistic regression that predicted POS (Overall model, p < 0.0001; AUC_centers = 0.93, AUC_guards = 0.88, AUC_forwards = 0.80), but only maxSPD, totDEC, totJUMP, and totMECH were significant contributors to the model's success (p < 0.0001 for each). Even with the high significance, the model still had some issues differentiating between guards and forwards, as in-game demands often overlap between the two positions. Nevertheless, the PCA was effective at simplifying a large external load dataset collected on NCAA DI men's basketball athletes. These data revealed that maxSPD, totDEC, totJUMP, and totMECH were the most sensitive to positional differences during competitions. To best characterize competition demands, such variables may be used to individualize training and recovery regimens most effectively.

Effects of Six Weeks of Flywheel Single-Leg Romanian Deadlift Training on Speed, Jumping and Change of Direction Performance

Several studies have confirmed the efficacy of flywheel training, mainly in the bilateral half-squat exercise. The aim of the present study was to analyze the effects of single-leg Romanian deadlift flywheel training on speed, jumping and change of direction performance. Seventeen young healthy males underwent two periods of 3-week training based on two weekly sessions of 3 sets × 7 repetitions or 4 sets × 7 repetitions of single-leg Romanian deadlifts (0.037 kg/m² moment inertia) with their dominant and non-dominant leg. After the first three weeks of the program, the CMJ, the 10 m, 30 m and total sprint times, as well as the COD-90 test, presented likely substantial beneficial effects and a small decrease in the relationship between the sprint and COD-90 test performance. After the second period of the three-week training, likely detrimental effects were observed in some of the change of direction conditions and an increase in the relationship between the sprint and the COD-180 performance. It could be hypothesized that most of the flywheel training effects reported in the traditional protocols lasting a minimum of 5–6 weeks would occur in the first weeks of training.

The use of real-time monitoring during flywheel resistance training programmes: how can we measure eccentric overload? A systematic review and meta-analysis

This systematic review and meta-analysis aimed to analyse the technologies and main training variables used in the literature to monitor flywheel training devices in real time. In addition, as the main research question, we investigated how eccentric overload can be effectively monitored in relation to the training variable, flywheel shaft type device and the moment of inertia selected. The initial search resulted in 11,621 articles that were filtered to twenty-eight and seventeen articles that met the inclusion criteria for the systematic review and meta-analysis, respectively. The main technologies used included force sensors and rotary/linear encoders, mainly to monitor peak or mean force, power or speed. An eccentric overload was not always achieved using flywheel devices. The eccentric overload measurement was related to the main outcome selected. While mean force (p = 0.011, ES = -0.84) and mean power (p < 0.001, ES = -0.30) favoured the concentric phase, peak power (p < 0.001, ES = 0.78) and peak speed (p < 0.001, ES = 0.37) favoured the eccentric phase. In addition, the lower moments of inertia (i.e., from 0.01 to 0.2 kg·m²) and a cylindrical shaft type (i.e., vs conical pulley) showed higher possibilities to achieve eccentric overload. A wide variety of technologies can be used to monitor flywheel devices, but to achieve eccentric overload, a flywheel cylindrical shaft type with low moments of inertia is advised to be used.

Preventive effect of tailored exercises on patellar tendinopathy in elite youth athletes: A cohort study

OBJECTIVE

To investigate the effects of an intervention with tailored exercises on the incidence of patellar tendinopathy (PT) in elite youth jumping athletes.

DESIGN

Prospective crossover cohort.

SETTING

One sport club facility.

PARTICIPANTS

271 elite youth basketball and volleyball player were followed in the first year of the study (Observation year) and 270 athletes were followed in the second year (intervention year).

MAIN OUTCOME MEASURE

Incidence rates of PT per 1,000h of exposure. Cox survival analysis was used to verify the effects of the intervention (exercises implemented according to the findings of a preseason assessment) on PT incidence.

RESULTS

The exercise prevention program significantly reduced the number of cases of PT, with athletes submitted to the intervention showing 51% less risk of developing PT. The overall PT incidence in the Observation year (5.9 per 1,000h of exposure) was significantly higher than that in the intervention year (2.8 per 1,000h of exposure) (P = .037). Twenty-six athletes developed PT in the observation year, whereas 13 athletes developed PT in the intervention year.

CONCLUSIONS

A tailored preventive program may be able to reduce the incidence of patellar tendinopathy, especially in male youth volleyball athletes. Randomized controlled trials are encouraged to confirm these findings.

Assessment and Evaluation of Force–Velocity Variables in Flywheel Squats: Validity and Reliability of Force Plates, a Linear Encoder Sensor, and a Rotary Encoder Sensor

Research into flywheel (FW) resistance training and force–velocity–power (F–v–P) profiling has recently gained attention. Ground reaction force (GRF) and velocity (v) during FW squats can be predicted from shaft rotational data. Our study aimed to compare the inter-set reliability of GRF, v, and F–v–P relationship output variables calculated from force plates and linear encoder (presumed gold-standard) and rotary encoder data. Fifty participants performed two sets of FW squats at four inertias. Peak and mean concentric and eccentric GRF, v, and F–v–P outcomes from mean variables during the concentric phase of the squat were calculated. Good to excellent reliability was found for GRF and v (ICC > 0.85), regardless of the measure and the variable type. The F–v–P outcomes showed moderate to good reliability (ICC > 0.74). Inter-measure bias (p < 0.05) was found in the majority of GRF and v variables, as well as for all the calculated F–v–P outcomes (trivial to large TEs) with very large to perfect correlations for v (r 0.797–0.948), GRF (r 0.712–0.959), and, finally, F–v–P outcomes (ICC 0.737–0.943). Rotary encoder overestimated the force plates and linear encoder variables, and the differences were dependent on the level of inertia. Despite high reliability, FW device users should be aware of the discrepancy between the measures.

Variability in the Application of Eccentric Force Using Different Rotary Inertia Devices May Influence the Treatment of Tendinopathy

High intraset variability has been considered as a potential aid in the treatment of tendinopathy by producing forces in variable and unpredictable contexts that allow the athlete to return to sport pain free. The aim of this study was to compare the intraset variability in force profiles between different rotational inertia devices (RIDs) during concentric and eccentric (ECC) phases of movement and between different moments of inertia. Thirty-nine men performed a half-squat incremental test on 2 different RIDs: a horizontal cylinder and a vertical cone-shaped axis. Intraset variabilities in vertical force and velocity were analyzed using average coefficients of variation. RID squat exercise produced force intraset variability. The ECC phase of the movement showed more intraset variability in force output than the concentric phase. ECC vertical cone-shaped shaft showed a higher intraset variability in force than ECC horizontal cylinder-shaped shaft. This study demonstrated that using an RID to provide resistance in squat training of athletes produced a high intraset variability in the application of force.

Inertial flywheel vs heavy slow resistance training among athletes with patellar tendinopathy: A randomised trial

OBJECTIVES

To compare the efficacy of inertial flywheel and heavy slow resistance training in reducing pain and improving function in patellar tendinopathy.

DESIGN

Randomised clinical trial.

METHODS

Fourty two participants (1 woman, 41 men) with longstanding (>3 months) patellar tendinopathy were randomised into inertial flywheel resistance (N = 21) or heavy slow resistance (N = 21) group. Both programmes consisted of three supervised inertial flywheel or heavy slow resistance exercise sessions per week in a fitness center during 12 weeks. Primary outcome was pain and function, assessed by the Spanish Victorian Institute of Sport Assessment for Patella (VISA-P) score at 6 and 12 weeks. Secondary outcomes were activity limitation using Patient Specific Functional Scale (PSFS), health status (EuroQol-5D), patient impression of change on pain and function, adherence, adverse events, pain provocation test for the patellar tendon (numerical rating score of pain between 0 and 10), physical test, patellar tendon thickness and doppler signal on ultrasound. Secondary outcomes were taken at 0 and 12 weeks.

RESULTS

Both groups showed significant improvements in VISA-P scores from 0 to 12 weeks but there was not statistically significant between-group difference (P = 0.506). No adverse events or side effects occurred in any of the groups during the intervention period.

CONCLUSIONS

Inertial flywheel resistance three times a week during 12 weeks resulted in similar pain and function benefit at 12 weeks compared with the heavy slow resistance training among people with patellar tendinopathy. Flywheel training is another exercise option for managing people with patellar tendinopathy. CLINICALTRIALS.

GOV REGISTRY

NCT03917849.

Chronic effects of flywheel training on physical capacities in soccer players: a systematic review

The aims of the current systematic review were to evaluate the current literature surrounding the chronic effect of flywheel training on the physical capacities of soccer players, and to identify areas for future research to establish guidelines for its use.Studies were identified following a search of electronic databases (PubMed and SPORTDiscus) in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA).Eleven studies met the inclusion criteria and were included. The methodological quality of the included studies ranged between 10 and 18 with an average score of 15 points using the PEDro scale. The training duration ranged from 6 weeks to 27 weeks, with volume ranging from 1 to 6 sets and 6 to 10 repetitions, and frequency from 1 to 2 times a week. This systematic review reported that a diverse range of flywheel training interventions can effectively improve strength, power, jump, and changes of direction in male soccer players of varying levels.Flywheel training interventions improve the physical capacities of soccer players of varying levels. Nonetheless, the current literature suggests contrasting evidence regarding flywheel training induced changes in sprint speed and acceleration capacity of soccer players.

Flywheel or free weight training for improvement of lower limbs strength?

BACKROUND

New training methods are constantly used to improve the ability of skeletal muscles to develop strength.

OBJECTIVE

The aim of the present study was to investigate the effect of half-squat training with free weights and flywheel device on isokinetic knee muscle strength for well-trained amateur soccer players.

METHODS

Forty eight players were randomly divided into three groups (n= 16 each): Desmotech Training group (DT), Free Weight Training group (WT) and one Control Group (CON). DT and WT performed an eight-week half-squat training program, with two sessions per week. The DT group performed training with a flywheel device. Isokinetic concentric-eccentric strength assessments of the knee extensors-flexors muscle groups were performed at different angular velocities (60, 180 and 240∘/s).

RESULTS

The eight-week training program improved all the isokinetic joint moment indicators examined in the DT and WT groups (p< 0.01). The DT group achieved higher performances at all the isokinetic parameters examined, however, without statistically significant differences to the WT group.

CONCLUSIONS

Flywheel-based exercise is an effective training method and is suggested to be used to strengthen the lower limbs of soccer players.

The effects of free weights and iso-inertial resistance during semi-squatting exercise on amateur soccer players' physical performance indicators: a randomized controlled study

BACKGROUND

The aim was to compare the effects of two lower extremity strengthening programs using iso-inertial resistance or free weights on amateur soccer players' physical performance indicators.

METHODS

Thirty-five amateur soccer players (average age 22.6±5.1 years) were randomly assigned to iso-inertial group (n=11) or free-weight group (n=11), or control group (n=13). The groups performed two training sessions per week for six weeks. Before and after the strengthening implementation, physical performance indicators were evaluated, including the isokinetic knee extensors and flexors' strength, power, speed, and agility. The significance level was set at p<0.05.

RESULTS

The iso-inertial training resistance led to an increase in the hamstrings' eccentric strength at 60°/s and 150°/s (p<0.05) compared to the free-weight resistance (p>0.05) and the controls (p>0.05). No other significant adaptations were observed in the other isokinetic strength, power, speed (10-m, p=0.052) and agility measurements (Illinois agility test, p=0.059). In ratio (knee flexors/knee extensors) the only differences observed was at 150 o/s for iso-inertial group (p<0.05).

CONCLUSIONS

Iso-inertial resistance training during semi squatting can enhance the hamstrings' eccentric performance andthe soccer players' speed and agility compared to the classic free-weight training program, which should considered when designing strength and injury prevention programs.

Effects of Flywheel Resistance Training on Sport Actions. A Systematic Review and Meta-Analysis

The purpose of the present meta-analysis was to examine the effect of flywheel resistance training (FRT) on main sport action (i.e., jumping performance, sprinting time and change of direction performance) improvements in athletes and healthy active people. A Boolean search strategy adapted for each of the databases employed was conducted to identify all studies measuring change in sport actions performance after FRT interventions up to July 2019. Outcomes were analysed using an average effect size (D₊) and a 95% confidence interval (CI), which was calculated assuming a random-effects model. A total of 9 studies with 283 participants met the inclusion criteria and were selected for the analysis. The mean quality score (PEDro scale) of the articles included in the meta-analysis was 5.67. The meta-analysis showed significant positive effects on jumping performance (SMC 0.65; 95% CI, 0.11-1.19; p = 0.02), sprinting time (SMC 1.33; 95% CI, 0.39-2.28; p < 0.01) and change of direction performance (SMC 1.36; 95% CI, 0.58-2.14; p < 0.01) after FRT interventions compared to control/traditional resistance training groups. The results of the present meta-analysis provide evidence of the usefulness of FRT to improve variables related to sport performance in both athletes and healthy population.

Greater Power but Not Strength Gains Using Flywheel Versus Equivolumed Traditional Strength Training in Junior Basketball Players

The main aim of the present study was to compare the effects of flywheel strength training and traditional strength training on fitness attributes. Thirty-six well trained junior basketball players (n = 36; 17.58 ± 0.50 years) were recruited and randomly allocated into: Flywheel group (FST; n = 12), traditional strength training group (TST; n = 12) and control group (CON; n = 12). All groups attended 5 basketball practices and one official match a week during the study period. Experimental groups additionally participated in the eight-week, 1–2 d/w equivolume intervention conducted using a flywheel device (inertia = 0.075 kg·m⁻²) for FST or free weights (80%1 RM) for TST. Pre-to post changes in lower limb isometric strength (ISOMET), 5 and 20 m sprint time (SPR5m and SPR20m), countermovement jump height (CMJ) and change of direction ability (t-test) were assessed with analyses of variance (3 × 2 ANOVA). Significant group-by-time interaction was found for ISOMET (F = 6.40; p = 0.000), CMJ (F = 7.45; p = 0.001), SPR5m (F = 7.45; p = 0.010) and T test (F = 10.46; p = 0.000). The results showed a significantly higher improvement in CMJ (p = 0.006; 11.7% vs. 6.8%), SPR5m (p = 0.001; 10.3% vs. 5.9%) and t-test (p = 0.045; 2.4% vs. 1.5%) for FST compared to the TST group. Simultaneously, th FST group had higher improvement in ISOMET (p = 0.014; 18.7% vs. 2.9%), CMJ (p = 0.000; 11.7% vs. 0.3%), SPR5m (p = 0.000; 10.3% vs. 3.4%) and t-test (p = 0.000; 2.4% vs. 0.6%) compared to the CON group. Players from the TST group showed better results in CMJ (p = 0.006; 6.8% vs. 0.3%) and t-test (p = 0.018; 1.5% vs. 0.6%) compared to players from the CON group. No significant group-by-time interaction was found for sprint 20 m (F = 2.52; p = 0.088). Eight weeks of flywheel training (1–2 sessions per week) performed at maximum concentric intensity induces superior improvements in CMJ, 5 m sprint time and change of direction ability than equivolumed traditional weight training in well trained junior basketball players. Accordingly, coaches and trainers could be advised to use flywheel training for developing power related performance attributes in young basketball players.

Influence of Load and Phase of Contraction on Lateral Symmetries in Flywheel Squats

Assessment of lateral symmetries (LS) of lower limbs has been widely investigated. However, there are no studies about LS during exposure to high eccentric and concentric loads during flywheel (FW) squats. A total of 422 young, physically active participants performed squats on an FW device with different equidistant loads (0.05, 0.125 and 0.2 kg∙m2). The mean and peak force of the left and right leg were assessed for the concentric and eccentric contaction phase. LS values were calculated for each load and phase of squat. Our results showed that the absolute mean and peak force of the concentric and eccentric phase of contraction had excellent reliability, while LS values were more reliable when eccentric force was used for their calculation. Mean and peak forces were increased with the higher FW load. In general, we found a decrease in LS values in the concentric phase of contraction with the higher load. Moreover, values of LS are similar to a wide range of other functional movements. Nevertheless, symmetrical force application during squatting on a FW device should be satisfied regardless of the FW load. Due to the large sample size, our results are valuable as a reference point when athletes are evaluated during training.

Effects of flywheel training on strength-related variables in female populations. A systematic review

This study aimed to evaluate the effect of flywheel training on female populations, report practical recommendations for practitioners based on the currently available evidence, underline the limitations of current literature, and establish future research directions. Studies were searched through the electronic databases (PubMed, SPORTDiscus, and Web of Science) following the preferred reporting items for systematic reviews and meta-analysis statement guidelines. The methodological quality of the seven studies included in this review ranged from 10 to 19 points (good to excellent), with an average score of 14-points (good). These studies were carried out between 2004 and 2019 and comprised a total of 100 female participants. The training duration ranged from 5 weeks to 24 weeks, with volume ranging from 1 to 4 sets and 7 to 12 repetitions, and frequency ranged from 1 to 3 times a week. The contemporary literature suggests that flywheel training is a safe and time-effective strategy to enhance physical outcomes with young and elderly females. With this information, practitioners may be inclined to prescribe flywheel training as an effective countermeasure for injuries or falls and as potent stimulus for physical enhancement.

Recent advances in tendinopathy

Tendinopathy refers to the clinical diagnosis of activity-related pain resulting in a decline in tendon function. In the last few years, much has been published concerning the basic science and clinical investigation of tendinopathy and debates and discussions to new questions and points of view started many years ago. This advances review will discuss the current thinking on the basic science and clinical management of tendinopathy and in particular new findings in the tendon repair space that are relevant to the pathophysiology of tendinopathy. We will further discuss potential novel therapies on the horizon in human tendon disease.

Lower Extremities Strength Differences in Female Volleyball Players With Stage 1 Patellar Tendinopathy

Kabacinski, J, Murawa, M, Fryzowicz, A, Gorwa, J, and Dworak, LB. Lower extremities strength differences in female volleyball players with stage 1 patellar tendinopathy. J Strength Cond Res XX(X): 000-000, 2020-The main purpose of the study was to compare the muscle strength between the involved knee (IK) and uninvolved knee (UK) in 12 female volleyball players with stage 1 chronic patellar tendinopathy. Evaluation included the isometric maximal strength to body mass (MS/BM) of the lower extremities extensors for unilateral and bilateral conditions, concentric isokinetic peak torque to body mass (PT/BM) of the hamstrings and quadriceps at 60°·s and 180°·s, IK to UK extensors maximal strength ratio (SR), IK to UK hamstrings (or quadriceps) peak torque ratio (TR), and hamstrings to quadriceps peak TR (H/Q). The results indicated a significantly lower unilateral and bilateral MS/BM of lower extremities extensors for IK than UK (p < 0.001). However, there were no significant differences in SR variable between the unilateral condition and bilateral condition (p = 0.448). Only at the 60°·s velocity, significantly lower quadriceps PT/BM for IK compared with the UK (p < 0.001) and the control group (p < 0.001) were observed. Torque ratio related to the quadriceps group was significantly lower at 60°·s than 180°·s (p = 0.004). Furthermore, significantly higher H/Q for IK compared with UK (p < 0.001) and control group (p = 0.008) only at 60°·s was found. These findings show a significant isometric strength asymmetry for both unilateral and bilateral conditions and a significant concentric strength asymmetry at the low velocity. This study suggests strengthening the weaker quadriceps group and balancing the strength between hamstrings and quadriceps within the knee with patellar tendinopathy.

Strength Conditioning Program to Prevent Adductor Muscle Strains in Football: Does it Really Help Professional Football Players?

Coaches at the professional level are often concerned about negative side effects from testing and intensive resistance training periods, and they are not willing to base their training prescriptions on data obtained from semiprofessional or amateur football players. Consequently, the purpose of this study was to analyze the reliability and effectiveness of two adductor injury active prevention programs using the adductor/abductor ratio and deficit between legs, on the basis of adduction-abduction power output during the exercises proposed, in professional football players. Forty-eight professional football players undertook complementary strength training for the adductor and abductor muscles in their dominant and non-dominant legs, once or twice a week throughout the playing season. The volume of the session was determined by the adductor/abductor ratio and the deficit between legs in the last session training measured. The number and severity of muscle injuries per 1000 h of exposure were recorded. Both prevention programs showed a very low rate of adductor injury (0.27 and 0.07 injuries/1000 h) with mild-to-moderate severity, maintaining a balance in percentage asymmetry between dominant and non-dominant legs for adductor (10.37%) and in the adductor/abductor ratio (0.92) in top professional football players throughout the season. The strength conditioning program proposed can help to prevent adductor muscle injuries in top professional football players.

Rotational flywheel training in youth female team sport athletes: could inter-repetition movement variability be beneficial?

BACKGROUND

The aim of this study was to analyze the effects of an inter-repetition variable rotational flywheel training program (variable) over standard rotational flywheel training (Standard).

METHODS

Twenty-four youth female team-sports players were randomly assigned to both training groups (variable, N.=12; standard, N.=12), which consisted of 1 set of 3 rotational flywheel exercises ×10-12 repetitions, biweekly for a period of 6-weeks. The participants included in variable group were instructed to perform the movement randomly in one of the three directions (0°, 45° right, and 45° left). Measurements included reactive strength, jumping, change of direction, and sprinting tests; patellar tendon condition was also assessed.

RESULTS

Substantial improvements were found in vertical jump with left leg (16.9%), lateral jump with right leg (13.6%), and patellar condition in left leg (4.1%) for standard group, but also in reactive strength index in right leg landing (33.9%), vertical jump with right (10.1%) and left leg (12.0%) for variable group. A significant interaction effect (group × time) was observed on patellar condition in right leg (F=10.02, P<0.01, η²=0.37), favoring variable group.

CONCLUSIONS

Rotational flywheel training programs were beneficial for youth-female team-sports athletes, although the movement variability may play a key role to develop different and specific physical adaptations.

How Are Mechanical, Physiological, and Perceptual Variables Affected by the Rest Interval Between Sets During a Flywheel Resistance Session?

The use of flywheel devices has increased in popularity during the last few years. Flywheel training is an attractive alternative to traditional resistance exercise because it allows for the loading stimulus to be manipulated. Some of the benefits associated with flywheel training include increases in muscle hypertrophy, muscular strength and reductions in injury risk. Nevertheless, there is a lack of research about how basic training variables [i.e., rest intervals (RI) between sets], or variables associated with manipulation of the loading stimulus (i.e., different inertial loads), influence the acute responses during a flywheel session. Thus, the aim of this study was to assess the influence of three different RI between sets (1, 2, or 3 min), during a flywheel squat session with two different inertial loads: light (0.025 kg⋅m²) and high (0.075 kg⋅m²). Twenty-three participants performed six exercise sessions (two inertial loads × three RI) consisting of four sets of 11 repetitions. Concentric and eccentric power, lactate concentration ([La]) and ratings of perceived exertion (RPE) were measured during the exercise session, and delayed onset muscular soreness (DOMS) were recorded 24 h post-exercise. Both concentric (9.1 and 22.1% at light and high load respectively; p = 0.022 and 0.005) and eccentric peak power (17.5% at high load; p = 0.02) decreased across sets when the 1 min RI was used. Concentric peak power was decreased (11.1%, p = 0.041) from the 2 min RI only with the high inertial load. RPE was higher during the 1 min compared with the 3 min RI protocol when using the high inertial load (p = 0.028). [La] was higher when using the 2 min RI compared with the 3 min RI at light load (p = 0.03). In conclusion, during flywheel training sessions, a short RI (1 min) was insufficient to maintain power output across all four sets and was linked to greater perceptual variables. A 2 min RI allowed for power to be maintained, but only when training with light inertial loads. Based on these results, coaches should consider prescribing 3 min RI’s when performing flywheel squat exercises regardless the inertial load. In contrast, when using 2 min RI’s the inertial load should be light.

Eccentric-Overload Production During the Flywheel Squat Exercise in Young Soccer Players: Implications for Injury Prevention

This study aimed to evaluate the differences in power production between movement phases (i.e., concentric and eccentric) during the execution of resistance exercises with a flywheel device, differentiating between execution regimes (i.e., bilateral, unilateral dominant leg and unilateral non-dominant leg). Twenty young elite soccer players (U-17) performed two sets of six repetitions of the bilateral half-squat (inertia 0.025 kg·m-2) and the lateral-squat exercise (inertia 0.010 kg·m-2) on a flywheel device. During the testing sessions, mean and peak power in concentric (MPcon) and eccentric (MPecc) phases were recorded. The non-dominant leg showed higher values in all power variables measured, although substantial differences were only found in MPecc (ES = 0.40, likely) and PPcon (ES = 0.36, possibly). On the other hand, for both exercises, MPcon was higher than MPecc (ES = -0.57 to -0.31, possibly/likely greater), while only PPecc was higher than PPcon in the dominant lateral-squat (ES = 0.44, likely). These findings suggest that young soccer players have difficulty in reaching eccentric-overload during flywheel exercises, achieving it only with the dominant leg. Therefore, coaches should propose precise preventive programs based on flywheel devices, attending to the specific characteristics of each limb, as well as managing other variables to elicit eccentric-overload.

Comparative study of treatment interventions for patellar tendinopathy: a protocol for a randomised controlled trial

INTRODUCTION

Patellar tendinopathy is a degenerative disease of the patellar tendon, which affects athletes from a variety of sports, and is especially predominant in sports involving high-impact jumping. The aim of this study is to determine the additional effect of two interventions combined with eccentric exercise and compare which one is the most effective at short-term and long-term follow-up for patients with patellar tendinopathy.

METHODS AND ANALYSIS

This study is a randomised controlled trial with blinded participants. Measurements will be carried out by a specially trained blinded assessor. A sample of 57 patients with a medical diagnosis of patellar tendinopathy will participate in this study and will be divided into three treatment groups. Eligible participants will be randomly allocated to receive either: (a) treatment group with percutaneous needle electrolysis, (b) treatment group with dry needling or (c) treatment group with placebo needling. In addition, all groups will perform eccentric exercise. Functionality and muscle strength parameters, pain, ultrasound appearances and patient perceived quality of life shall be evaluated using the Victorian Institute of Sports Assessment for patellar (VISA-P), jump tests, Visual Analogue Scale, ultrasound images and Short Form-36 (SF-36), respectively. Participants will be assessed at baseline, at 10 weeks and at 22 weeks after baseline. The expected findings will allow us to advance in the treatment of this injury, as they will help determine whether a needling intervention has additional effects on an eccentric exercise programme and whether any of the needling modalities is more effective than the other.

ETHICS AND DISSEMINATION

This protocol has been approved by the Ethics Committee of Aragon (N° PI15/0017). The trial will be conducted in accordance with the Declaration of Helsinki.

TRIAL REGISTRATION NUMBER

NCT02498795.

Eccentric Resistance Training in Youth: Perspectives for Long-Term Athletic Development

The purpose of this narrative review is to discuss the role of eccentric resistance training in youth and how this training modality can be utilized within long-term physical development. Current literature on responses to eccentric exercise in youth has demonstrated that potential concerns, such as fatigue and muscle damage, compared to adults are not supported. Considering the importance of resistance training for youth athletes and the benefits of eccentric training in enhancing strength, power, speed, and resistance to injury, its inclusion throughout youth may be warranted. In this review we provide a brief overview of the physiological responses to exercise in youth with specific reference to the different responses to eccentric resistance training between children, adolescents, and adults. Thereafter, we discuss the importance of ensuring that force absorption qualities are trained throughout youth and how these may be influenced by growth and maturation. In particular, we propose practical methods on how eccentric resistance training methods can be implemented in youth via the inclusion of efficient landing mechanics, eccentric hamstrings strengthening and flywheel inertia training. This article proposes that the use of eccentric resistance training in youth should be considered a necessity to help develop both physical qualities that underpin sporting performance, as well as reducing injury risk. However, as with any other training modality implemented within youth, careful consideration should be given in accordance with an individual's maturity status, training history and technical competency as well as being underpinned by current long-term physical development guidelines.

Implementing Eccentric Resistance Training-Part 2: Practical Recommendations

The purpose of this review is to provide strength and conditioning practitioners with recommendations on how best to implement tempo eccentric training (TEMPO), flywheel inertial training (FIT), accentuated eccentric loading (AEL), and plyometric training (PT) into resistance training programs that seek to improve an athlete's hypertrophy, strength, and power output. Based on the existing literature, TEMPO may be best implemented with weaker athletes to benefit positional strength and hypertrophy due to the time under tension. FIT may provide an effective hypertrophy, strength, and power stimulus for untrained and weaker individuals; however, stronger individuals may not receive the same eccentric (ECC) overload stimulus. Although AEL may be implemented throughout the training year to benefit hypertrophy, strength, and power output, this strategy is better suited for stronger individuals. When weaker and stronger individuals are exposed to PT, they are exposed to an ECC overload stimulus as a result of increases in the ECC force and ECC rate of force development. In conclusion, when choosing to utilize ECC training methods, the practitioner must integrate these methods into a holistic training program that is designed to improve the athlete's performance capacity.

Epidemiological Patterns of Patellofemoral Injuries in Collegiate Athletes in the United States From 2009 to 2014

Background

As many as 30% of patients with knee pain seen in sports medicine clinics have complaints related to the patellofemoral joint. There is a paucity of research available regarding patellofemoral injuries, mechanism of injury, and playing time lost in collegiate athletes.

Purpose

To describe the rates, mechanisms, severity, and potential sex-based differences of patellofemoral injuries in collegiate athletes across 25 National Collegiate Athletic Association (NCAA) sports.

Study Design

Descriptive epidemiology study.

Methods

Data from the 2009-2010 through the 2013-2014 academic years were obtained from the NCAA Injury Surveillance Program and were analyzed to calculate patellofemoral injury rates, mechanisms of injury, time lost, and need for surgery. Rate ratios and injury proportion ratios were used to quantify discernible differences between sex-comparable sports and timing of injury (ie, practice vs competition), respectively.

Results

The overall patellofemoral injury incidence rate was 16.10 per 100,000 athlete-exposures (AEs). Women's volleyball had the highest incidence of all sports (39.57 per 100,000 AEs). Injuries were 66% more likely to occur in competition than during practice. Female athletes experienced significantly more patellofemoral injuries than males in similar sports. Patellar tendinitis accounted for 49.2% of all patellofemoral injuries and was the most common injury in 20 of 25 studied sports. Patellar subluxation accounted for the most total days missed, and patellar dislocation had the highest mean days missed per injury (11.42 days). Patella fracture was the most likely injury to require surgery (80%).

Conclusion

Patellofemoral injuries were most common in sports that require jumping and quick changes of direction, specifically women's volleyball, men's and women's basketball, and women's soccer. The majority of patellofemoral injuries in this cohort were classified as patellar tendinitis caused by overuse. Most injuries resulted in no competition or practice time lost. This information may contribute to the development of prevention programs aimed at addressing the most prevalent types and mechanisms of injury in each sport to reduce the incidence of patellofemoral injury in these athletes.

Differential effects of low vs. high inertial loads during an eccentric-overload training intervention in rugby union players: a preliminary study

BACKGROUND

Eccentric overload training (EOT) has been proposed as an effective stimulus to optimize dynamic athletic performance. Nevertheless, the appropriate intensity during EOT remains unknown. The purpose of this study was to evaluate the influence of the inertial load used during an EOT program on performance adaptations in rugby union players.

METHODS

Fifteen rugby players were divided into a low (0.025 kg·m2; G 0.025) or a high (0.075 kg·m2; G 0.075) inertial load for training. Both groups trained using the flywheel half squat exercise twice a week during the seven-week EOT. Athletic performance was evaluated by testing the half squat maximum repetition (1RM), countermovement jump (CMJ), 40 m linear sprint, the modified agility T-Test, and power output in the flywheel squat exercise. Data were analysed using magnitude-based inferences.

RESULTS

Both groups improved their 1RM and CMJ to a similar extent. Nevertheless, the G 0.025 showed likely trivial changes in linear sprint (ES=-0.02), and possibly positive effects on the agility T-Test (ES=0.16), while the G 0.075 showed possibly negative effects on 40 m linear sprint (ES=-0.23) and likely trivial effects on the T-Test (ES=0.07).

CONCLUSIONS

Due to the similar gains in 1RM and CMJ, and the superior maintenance in linear sprint, the use of low inertial loads during EOT may be a better option when looking for athletic performance optimization.

Comparison of the musculoskeletal effects of different iso-inertial resistance training modalities: Flywheel vs. electric-motor

This study aimed to analyse whether increasing the eccentric overload (EO) during resistance training, in terms of range of motion and/or velocity using an electric-motor device, would induce different muscle adaptations than conventional flywheel-EO resistance training. Forty physically active university students (21.7 ± 3.4 years) were randomly placed into one of the three training groups (EX1, EX2, FW) and a control group without training (n = 10 per group). Participants in the training groups completed 12 sessions (4 sets of 7 repetitions) of iso-inertial single-leg squat training over 6 weeks for the dominant leg. Resistance was generated either by an electric-motor device at two different velocities for the eccentric phase; 100% (EX1) or 150% (EX2) of concentric speed, or by a conventional flywheel device (FW). Thigh lean tissue mass, unilateral leg press one-repetition maximum (1-RM), unilateral muscle power at different percentages of the 1-RM and bilateral/unilateral vertical jump were assessed before and after the 6-week training. There were significant (p < 0.05-0.001) main effects of time in the 3 training groups, indicating increased thigh lean tissue mass (2.5-5.8%), 1-RM load (22.4-30.2%), vertical jump performance (9.1-32.9%) and muscle power (8.8-21.7%), without differences across experimental groups. Participants in the control group did not improve any of the variables measured. In addition, EX2 showed greater gains in eccentric average peak power during training than EX1 and FW (p < 0.001). Despite the different EO offered, 6 weeks of resistance training using flywheel or electric-motor devices induced similar significant gains in muscle mass, strength, muscle power and vertical jump.

Effects of Flywheel Training on Strength-Related Variables: a Meta-analysis

BACKGROUND

Strength and power development are abilities important for athletic performance in many sports. Generally, resistance training based on gravity is used to improve these qualities. Flywheel training instead utilizes kinetic energy transferred to a flywheel. This allows for eccentric overload and variable resistance throughout the movement. The aim of this review was to identify the effects of flywheel training on multiple strength-related variables affecting athletic performance. The meta-analysis investigates the effects on (1) muscle growth (cross-sectional area (CSA) and volume/mass), (2) maximum dynamic strength, (3) development of power, (4) development of horizontal movement, and (5) development of vertical movement.

METHODS

The meta-analysis includes 20 experimental studies that met the inclusion criteria. The quality of included studies was ranked according to the PEDro scale. Possible bias was identified in Funnel plot analyses. To enable the compilation of all results analyses, the random effect model was carried out using the software Review Manager Version 5.3 and presented with Forest plots.

RESULTS

Flywheel training for a period of 4-24 weeks shows statistically significant increases in all strength aspects. Effect sizes were for hypertrophy, CSA 0.59; volume/mass 0.59; maximum strength 1.33; power 1.19; horizontal 1.01 and vertical movement 0.85. The evidence is particularly strong for beneficial effects from flywheel training in the development of maximal strength and power in trained younger individuals, and utilization of this training modality in shorter more intensive blocks.

CONCLUSIONS

Flywheel training is an effective method for improving several aspects of strength and power with importance for sports performance.

Refractory patellar tendinopathy treated by arthroscopic decortication of the inferior patellar pole in athletes: Mid-term outcomes

BACKGROUND

This study aimed to evaluate the clinical outcomes of arthroscopic decortication of the inferior patellar pole in athletes with refractory chronic patellar tendinopathy.

METHODS

Thirty-seven athletes in whom conservative management for at least six months failed underwent arthroscopic patellar tendon debridement and decortication of the inferior pole of the patella. Clinical outcomes were evaluated using subjective knee scores and isokinetic muscle strength tests. The average duration taken and sports participation level were also assessed.

RESULTS

The mean follow-up period was 51.3 ± 14.8 months. At the last follow-up, all improvements in subjective knee scores including Lysholm score, International Knee Documentation Committee (IKDC) subjective score, Victorian Institute of Sport Assessment -Patella (VISA-P) score, and Kujala score were statistically significant (p<.001). Tegner activity scale improved from 6.5±1.0 to 8.9±0.8 (p<.001). Limb symmetry index for extensor peak torque improved from 71.4±19.6% to 92.7±21.7% (p<.001). Thirty-two (86.5 %) athletes were able to return to full sports activities in a mean 3.5±1.7months, and 27 (73%) athletes maintained their previous sports activity level at the last follow-up. Symptoms recurred in two (5.2%).

CONCLUSIONS

Arthroscopic decortication of the inferior pole of the patella showed satisfactory clinical results and high rates of return to sports at mid-term follow-up in professional athletes with refractory chronic patellar tendinopathy. This technique could be an invasive, safe, and effective treatment for chronic patellar tendinopathy in professional athletes who want a faster return to sports.

LEVEL OF EVIDENCE

Level IV, case series.

The effects of unilateral and bilateral eccentric overload training on hypertrophy, muscle power and COD performance, and its determinants, in team sport players

The study aimed to compare the chronic eccentric-overload training effects of unilateral (lateral lunge) vs bilateral (half-squat) using an inertial device, on hypertrophy and physical performance. Twenty-seven young team sports male players performed a 4 sets of 7 repetitions of inertial eccentric overload training, biweekly for 6 weeks, distributed in unilateral lunge group (UG: age: 22.8 ± 2.9 years; body mass: 75.3 ± 8.8 kg; height: 177.3 ± 3.7 cm) and bilateral squat group (BG: age: 22.6 ± 2.7 years; body mass: 79.5 ± 12.8 kg; height: 164.2 ± 7 cm). Lower limb muscle volume, counter movement jump (CMJ), power with both (POWER), dominant (POWERd) and no-dominant leg (POWERnd), change of direction turn of 90° with dominant (COD90d) and no-dominant leg (COD90nd) and 180° (COD180d and COD180nd), and 10m sprint time (T-10m) were measured pre and post-intervention. The UG obtained an increase of adductor major (+11.1%) and vastus medialis (+12.6%) higher than BG. The BG obtained an increase of vastus lateralis (+9.9%) and lateral gastrocnemius (+9.1%) higher than UG. Both groups improved CMJ, POWER, POWERd, POWERnd, COD90 and DEC-COD90, without changes in T-10m. The UG decrease DEC-COD90nd (-21.1%) and BG increase POWER (+38.6%) substantially more than the other group. Six-weeks of unilateral / bilateral EO training induce substantial improvements in lower limbs muscle volume and functional performance, although unilateral training seems to be more effective in improving COD90 performance.

Is inertial flywheel resistance training superior to gravity-dependent resistance training in improving muscle strength? A systematic review with meta-analyses

OBJECTIVE

The primary aim of this systematic review was to determine if inertial flywheel resistance training is superior to gravity-dependent resistance training in improving muscle strength. The secondary aim was to determine whether inertial flywheel resistance training is superior to gravity-dependent resistance training in improving other muscular adaptations.

DESIGN

A systematic review with meta-analyses of randomised and non-randomised controlled trials.

METHODS

We searched MEDLINE, Scopus, SPORTDiscus, Web of Science and Cochrane Central Register of Controlled Trials with no publication date restrictions until November 2016. We performed meta-analyses on randomised and non-randomised controlled trials to determine the standardized mean difference between the effects of inertial flywheel and gravity-dependent resistance training on muscle strength. A total of 76 and 71 participants were included in the primary and secondary analyses, respectively.

RESULTS

After systematic review, we included three randomised and four non-randomised controlled trials. In the primary analysis for the primary outcome muscle strength, the pooled results from randomised controlled trials showed no difference (SMD=-0.05; 95%CI -0.51 to 0.40; p=0.82; I²=0%). In the secondary analyses of the primary outcome, the pooled results from non-randomised controlled trials showed no difference (SMD=0.02; 95%CI -0.45 to 0.49; p=0.93; I²=0%; and SMD=0.03; 95%CI -0.43 to 0.50; p=0.88; I²=0%). Meta-analysis on secondary outcomes could not be performed.

CONCLUSION

Based on the available data, inertial flywheel resistance training was not superior to gravity-dependent resistance training in enhancing muscle strength. Data for other strength variables and other muscular adaptations was insufficient to draw firm conclusions from.