Sports Medicine

Sports Medicine

Is Motorized Treadmill Running Biomechanically Comparable to Overground Running? A Systematic Review and Meta-Analysis of Cross-Over Studies

04-12-2019 –

Abstract Background Treadmills are often used in research, clinical practice, and training. Biomechanical investigations comparing treadmill and overground running report inconsistent findings. Objective This study aimed at comparing biomechanical outcomes between motorized treadmill and overground running. Methods Four databases were searched until June 2019. Crossover design studies comparing lower limb biomechanics during non-inclined, non-cushioned, quasi-constant-velocity motorized treadmill running with overground running in healthy humans (18–65 years) and written in English were included. Meta-analyses and meta-regressions were performed where possible. Results 33 studies (n = 494 participants) were included. Most outcomes did not differ between running conditions. However, during treadmill running, sagittal foot–ground angle at footstrike (mean difference (MD) − 9.8° 95% confidence interval: − 13.1 to − 6.6; low GRADE evidence), knee flexion range of motion from footstrike to peak during stance (MD 6.3° 4.5 to 8.2; low), vertical displacement center of mass/pelvis (MD − 1.5 cm − 2.7 to − 0.8; low), and peak propulsive force (MD − 0.04 body weights − 0.06 to − 0.02; very low) were lower, while contact time (MD 5.0 ms 0.5 to 9.5; low), knee flexion at footstrike (MD − 2.3° − 3.6 to − 1.1; low), and ankle sagittal plane internal joint moment (MD − 0.4 Nm/kg − 0.7 to − 0.2; low) were longer/higher, when pooled across overground surfaces. Conflicting findings were reported for amplitude of muscle activity. Conclusions Spatiotemporal, kinematic, kinetic, muscle activity, and muscle–tendon outcome measures are largely comparable between motorized treadmill and overground running. Considerations should, however, particularly be given to sagittal plane kinematic differences at footstrike when extrapolating treadmill running biomechanics to overground running. Protocol registration CRD42018083906 (PROSPERO International Prospective Register of Systematic Reviews).

The Minimum Effective Training Dose Required to Increase 1RM Strength in Resistance-Trained Men: A Systematic Review and Meta-Analysis

03-12-2019 –

Abstract Background Increases in muscular strength may increase sports performance, reduce injury risk, are associated with a plethora of health markers, as well as exerting positive psychological effects. Due to their efficiency and effectiveness in increasing total body muscular strength, multi-joint exercises like the powerlifts, i.e.: the squat (SQ), bench-press (BP) and deadlift (DL), are widely used by active individuals as well as athletes in the pursuit of increasing strength. To date, the concept of a minimum dose, i.e. “what is the minimum one needs to do to increase 1-repetition maximum (1RM) strength?” has not been directly examined in the literature, especially in the context of the powerlifts. This review aims to explore the current available evidence around the minimum effective training dose required to increase 1RM strength in trained individuals in an attempt to enhance the practical guidelines around resistance-training as well as provide active individuals, athletes and coaches with more flexibility when designing a training protocol. Methods One reviewer independently conducted the search in a PRISMA systematic approach using PubMed, Sport
Discus and Google Scholar databases. The databases were searched with the following search terms/phrases and Boolean operators: “training volume” AND “powerlifting” OR “1RM strength” OR “powerlifters”, “low volume” AND “powerlifting” OR “powerlifting” OR “1RM strength”, “high vs low volume” AND “powerlifting” OR “1RM strength”, “minimum effective training dose 1RM”. Meta-analyses were performed to estimate the change in 1RM strength for the lowest dose group in the included studies. Results From the initial 2629 studies, 6 studies met our inclusion criteria. All identified studies showed that a single set performed minimum 1 time and maximum 3 times per week was sufficient to induce significant 1RM strength gains. Meta-analysis of 5 studies showed an estimated increase for overall 1RM of 12.09 kg 95% CIs 8.16 kg–16.03 kg, an increase of 17.48 kg 95% CIs 8.51 kg–26.46 kg for the SQ, and 8.25 kg 95% CIs 0.68 kg–15.83 kg for the BP. All of the included studies contained details on most of the variables comprising “training dose”, such as: weekly and per session sets and repetitions as well as intensity of effort. Specific information regarding load (%1RM) was not provided by all studies. Conclusions The results of the present systematic review suggest that performing a single set of 6–12 repetitions with loads ranging from approximately 70–85% 1RM 2–3 times per week with high intensity of effort (reaching volitional or momentary failure) for 8–12 weeks can produce suboptimal, yet significant increases in SQ and BP 1RM strength in resistance-trained men. However, because of the lack of research, it is less clear as to whether these improvements may also be achievable in DL 1RM strength or in trained women and highly trained strength athletes. Registration This systematic review was registered with PROSPERO (CRD42018108911).

Correction to: Relationships Between Dry-land Resistance Training and Swim Start Performance and Effects of Such Training on the Swim Start: A Systematic Review

01-12-2019 – S Thng,S Pearson,JWL Keogh

Published Erratum

No sources of funding were used in the preparation of this article.

Correction to: Injury Incidence, Prevalence and Severity in High-Level Male Youth Football: A Systematic Review

01-12-2019 – S Jones,S Almousa,A Gibb,N Allamby,R Mullen,TE Andersen,M Williams

Published Erratum

First Key Point, sentence 2, which previously read:

Sex Dimorphism of VO 2max Trainability: A Systematic Review and Meta-analysis

01-12-2019 – C Diaz-Canestro,D Montero

Journal Article, Review

Abstract Background Increases in maximal oxygen uptake (VO2max) are strongly associated with improved cardiovascular health. Objective The aim was to perform a systematic review and meta-analysis to determine whether VO2max responses to endurance training (ET), the most effective intervention to improve VO2max, are influenced by sex. Methods We conducted a systematic search of MEDLINE and Web of Science since their inceptions until February 2019 for articles assessing the VO2max response to a given sex-matched dose of ET in healthy age-matched men and women. Meta-analyses were performed to determine the mean difference between VO2max responses in men versus women. Subgroup and meta-regression analyses were used to assess potential moderating factors. Results After systematic review, eight studies met the inclusion criteria. All studies implemented common modalities of ET in healthy untrained individuals, comprising a total of 175 men and women (90 ♂, 85 ♀). ET duration and intensity were sex-matched in all studies. After data pooling, ET induced substantially larger increases in absolute VO2max in men compared with women (mean difference = + 191 ml·min−1, 95% CI 99, 283; P < 0.001). A greater effect of ET on relative VO2max was also observed in men versus women (mean difference = + 1.95 ml·min−1·kg−1, 95% CI 0.76, 3.15; P = 0.001). No heterogeneity was detected among studies (I2 = 0%, P ≥ 0.59); the meta-analytical results were robust to potential moderating factors. Conclusion Pooled evidence demonstrates greater improvements in VO2max in healthy men compared with women in response to a given dose of ET, suggesting the presence of sexual dimorphism in the trainability of aerobic capacity.

The Effect of Training Interventions on Change of Direction Biomechanics Associated with Increased Anterior Cruciate Ligament Loading: A Scoping Review

01-12-2019 – T Dos’Santos,C Thomas,P Comfort,PA Jones

Journal Article, Review

Abstract Change of direction (COD) manoeuvres are associated with anterior cruciate ligament (ACL) injury risk due to the propensity to generate large multiplanar knee joint loads. Given the short- and long-term consequences of ACL injury, practitioners are interested in methods that reduce knee joint loads and subsequent ACL loading. An effective strategy to reduce ACL loading is modifying an athlete’s movement mechanics to reduce knee joint loading. The purpose of this scoping review was to critically appraise and comprehensively synthesise the existing literature related to the effects of training interventions on COD biomechanics associated with increased knee joint loads and subsequent ACL loading, and identify gaps and recommend areas for future research. A review of the literature was conducted using Medline and Sport DISCUS databases. Inclusion criteria consisted of pre-post analysis of a COD task, a minimum 4-week training intervention, and assessments of biomechanical characteristics associated with increased ACL loading. Of the 1,027 articles identified, 22 were included in the scoping review. Based on current literature, balance training and COD technique modification are the most effective training modalities for reducing knee joint loading (small to moderate effect sizes). One study reported dynamic core stability training was effective in reducing knee joint loads, but further research is needed to definitively confirm the efficacy of this method. Perturbation-enhanced plyometric training, the F-MARC 11 + soccer specific warm-up, Oslo Neuromuscular warm-up, and resistance training are ineffective training modalities to reduce COD knee joint loads. Conflicting findings have been observed for the Core-Pac and mixed training programme. Consequently, practitioners should consider incorporating balance and COD technique modification drills into their athletes’ training programmes to reduce potentially hazardous knee joint loads when changing direction. However, training intervention studies can be improved by investigating larger sample sizes (> 20), including a control group, acknowledging measurement error when interpreting their findings, and considering performance implications, to confirm the effectiveness of training interventions and improve adherence.

Acute Sport Concussion Assessment Optimization: A Prospective Assessment from the CARE Consortium

01-12-2019 – Geen auteurs bekend

Journal Article

Abstract Background Numerous medical organizations recommend a multifaceted approach to the assessment of concussion occurring during sporting events. A number of tools are available to clinicians, with a wide breadth of sensitivity and specificity; however, little work has been done to evaluate the combined efficiency of these tools in concussed male and female athletes from a broad array of collegiate sports and with variable time from the pre-season baseline evaluation. Objective The aim of this study was to optimize the concussion assessment battery for application within the first 72 h of injury, and to identify the necessary baseline retesting frequency. Methods Between 2014 and 2017, a total of 1458 National Collegiate Athletic Association (NCAA) athletes sustaining 1640 diagnosed concussions completed a baseline assessment each year of the investigation and were evaluated up to three times within the first 72 h of injury using a standardized assessment protocol. Classification and regression tree analyses were implemented to identify the most efficient multifaceted assessment pathway to quantify concussion-related outcomes. Results were optimized for assessments occurring within 1 h post-injury, 1–24 h post-injury, and 24–72 h post-injury when using the raw post-injury assessment performance, difference scores from baseline evaluations occurring in the same year, and difference scores from baseline evaluations occurring the year prior. Results At each of the assessment time points, the analyses indicated that alone or in combination, a symptom evaluation, Balance Error Scoring System (BESS) scores collected on the firm surface, and Standardized Assessment of Concussion (SAC) total score offered the best overall performance when compared with pre-morbid performance captured in the same season. Optimized sensitivity of the multifaceted approach was 61% within 1 h of injury, 67% at the 1–24 h interval, and 55% at the 24–72 h interval when difference scores from the same-season baseline were available. Conclusions This investigation identified key concussion assessments in quantifying post-concussion performance among student athletes, that were maximized when same-season pre-morbid evaluations were available. Consistent with clinical recommendations, medical professionals should continue to focus on symptom reporting, postural control, and neurocognitive screening to support the clinical examination when making a concussion diagnosis.

Injury Incidence, Prevalence and Severity in High-Level Male Youth Football: A Systematic Review

01-12-2019 – S Jones,S Almousa,A Gibb,N Allamby,R Mullen,TE Andersen,M Williams

Journal Article, Review

Abstract Background At a young age, high-level youth footballers enter structured practice where they engage in regular training and matches. The academy system is considered fundamental to a young footballer’s tactical, technical and physical development. Yet, with regular training and matches, high-level youth footballers may be exposed to the risk of injury. Objective This systematic review analyses and summarises published scientific information on high-level youth football injury characteristics and calculates the risk of them sustaining an injury over the course of a typical season. Methods The search was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Of the 1346 studies found, 23 fulfilled the inclusion criteria. Results Quality assurance scores for the selected research articles ranged between two and five out of eight. A high degree of heterogeneity between studies was observed. The probability of sustaining a time-loss injury during a high-level youth season ranged between < 1% and 96% for under 9- to under 16-year age groups and 50% and 91% for under 18- to under 21-year age groups. Pooled estimates for total (training and match) incidence per 1000 h was 5.8 for youth players aged under 9 to under 21 years, 7.9 for older players (under 17–under 21 years) and 3.7 for younger aged players (under 9–under 16 years). Training injury incidence rate ranged from 0.69 to 7.9 per 1000 h for all age groups in youth football. Match injury incidence rate for high-level youth players ranged from 0.4 to 80.0 per 1000 h. Close to one-fifth (18%) of all high-level youth football injuries were classified as severe and required > 28 days recovery time. Muscle strain injury accounted for 37% of all injuries reported in youth football. High probabilities (> 90%) of sustaining a time-loss injury over one typical high-level football season were found. Conclusion High-level youth players lose large portions of the seasonal development to injury, with players seemingly suffering long absences from training and matches, consequently affecting health and well-being and possibly burdening club/parental finances and healthcare systems.

The Translation of Sport Science Research to the Field: A Current Opinion and Overview on the Perceptions of Practitioners, Researchers and Coaches

01-12-2019 – HHK Fullagar,A McCall,FM Impellizzeri,T Favero,AJ Coutts

Journal Article

Abstract Evidence-based practice (EBP) is the collated integration of practitioner expertise, athlete values and research evidence aimed to optimise the decision-making process surrounding sport performance. Despite the academic interest afforded to sport science research, our knowledge of how this research is applied in elite sport settings is limited. This current opinion examines the existing evidence of the translation of sport science research into the field, with a tailored focus on the current perceptions of practitioners, researchers and coaches. Recent studies show that practitioners and researchers report they ascertain sport science knowledge differently, with coaches preferring personal interactions compared with coaching courses or scientific journals. The limited peer-reviewed research shows that coaches perceive their knowledge is greater in fields such as tactical/technical areas, rather than physical fitness or general conditioning. This likely explains coaches’ greater perceived value in research dedicated to technical and tactical expertise, as well as mental training and skill acquisition. Practitioners place a large emphasis on the need for research in physical fitness areas, which is likely due to their occupational focus. There are many perceived barriers of sport science research application, including funding, time, coach/player/staff ‘buy in’ and research questions that may not apply to the setting. We contend that researchers and practitioners may benefit in producing research, ascertaining knowledge and disseminating findings in alternative methods that better align with coaches’ needs. In addition, educational strategies that focus on real-world context and promote social interaction between coaches, practitioners, organisational personnel and researchers would likely benefit all stakeholders.

Acknowledgement to Referees

01-12-2019 –

Relationships Between Dry-land Resistance Training and Swim Start Performance and Effects of Such Training on the Swim Start: A Systematic Review

01-12-2019 – S Thng,S Pearson,JWL Keogh

Journal Article, Review

Abstract Background The swim start requires an explosive muscular response of the lower body musculature to effectively initiate movement off the starting blocks. There are currently key gaps in the literature evaluating the relationship between dry-land resistance training and swim start performance and the effects of this training on swim start performance, as assessed by the time to 5, 10 or 15 m. Objectives The aims of this systematic review were to critically appraise the current literature on (1) the acute relationship between dry-land resistance training and swim start performance and (2) the acute and chronic effects of dry-land resistance training on swim start performance. Methods An electronic search using Ausport
Med, Embase, Medline (Ovid), SPORTDiscus and Web of Science was performed. The methodological quality of the studies was evaluated using the Newcastle–Ottawa quality assessment scale (NOS) (cross-sectional studies) and the Physiotherapy Evidence Database (PEDro) scale (intervention studies). Results Sixteen studies met the eligibility criteria, although the majority did not utilise the starting blocks or technique currently used in elite swimming. Swim start performance was near perfectly related (r > 0.90) to vertical bodyweight jumps and jump height. Post-activation potentiation and plyometrics were found to produce significant improvements in acute and chronic swim start performance, respectively. Conclusion While there appears to be strong evidence supporting the use of plyometric exercises such as vertical jumps for monitoring and improving swim start performance, future studies need to replicate these findings using current starting blocks and techniques and compare the chronic effects of a variety of resistance training programmes.

Effects of Physical Exercise Training in the Workplace on Physical Fitness: A Systematic Review and Meta-analysis

01-12-2019 – O Prieske,T Dalager,M Herz,T Hortobagyi,G Sjøgaard,K Søgaard,U Granacher

Journal Article, Review

Abstract Background There is evidence that physical exercise training (PET) conducted at the workplace is effective in improving physical fitness and thus health. However, there is no current systematic review available that provides high-level evidence regarding the effects of PET on physical fitness in the workforce. Objectives To quantify sex-, age-, and occupation type-specific effects of PET on physical fitness and to characterize dose–response relationships of PET modalities that could maximize gains in physical fitness in the working population. Data Sources A computerized systematic literature search was conducted in the databases PubMed and Cochrane Library (2000–2019) to identify articles related to PET in workers. Study Eligibility Criteria Only randomized controlled trials with a passive control group were included if they investigated the effects of PET programs in workers and tested at least one fitness measure. Study Appraisal and Synthesis Methods Weighted mean standardised mean differences (SMDwm) were calculated using random effects models. A multivariate random effects meta-regression was computed to explain the influence of key training modalities (e.g., training frequency, session duration, intensity) on the effectiveness of PET on measures of physical fitness. Further, subgroup univariate analyses were computed for each training modality. Additionally, methodological quality of the included studies was rated with the help of the Physiotherapy Evidence Database (PEDro) Scale. Results Overall, 3423 workers aged 30–56 years participated in 17 studies (19 articles) that were eligible for inclusion. Methodological quality of the included studies was moderate with a median PEDro score of 6. Our analyses revealed significant, small-sized effects of PET on cardiorespiratory fitness (CRF), muscular endurance, and muscle power (0.29 ≤ SMDwm ≤ 0.48). Medium effects were found for CRF and muscular endurance in younger workers (≤ 45 years) (SMDwm = 0.71) and white-collar workers (SMDwm = 0.60), respectively. Multivariate random effects meta-regression for CRF revealed that none of the examined training modalities predicted the effects of PET on CRF (R2 = 0). Independently computed subgroup analyses showed significant PET effects on CRF when conducted for 9–12 weeks (SMDwm = 0.31) and for 17–20 weeks (SMDwm = 0.74). Conclusions PET effects on physical fitness in healthy workers are moderated by age (CRF) and occupation type (muscular endurance). Further, independently computed subgroup analyses indicated that the training period of the PET programs may play an important role in improving CRF in workers.

The Acute Neuromuscular Responses to Cluster Set Resistance Training: A Systematic Review and Meta-Analysis

01-12-2019 – C Latella,WP Teo,EJ Drinkwater,K Kendall,GG Haff

Journal Article, Review

Abstract Background Cluster sets (CSs) are a popular resistance training (RT) strategy categorised by short rest periods implemented between single or groups of repetitions. However, evidence supporting the effectiveness of CSs on acute intra-session neuromuscular performance is still equivocal. Objective The objective of this investigation was to determine the efficacy of a single session of CSs to attenuate losses in force, velocity and power compared to traditional set (TS) training. Methods Screening consisted of a systematic search of EMBASE, Google Scholar, PubMed, Scopus and SPORTDiscus. Inclusion criteria were (1) measured one or more of mean/peak force, velocity or power; (2) implemented CSs in comparison to TSs; (3) an acute design, or part thereof; and (4) published in an English-language, peer-reviewed journal. Raw data (mean ± standard deviation) were extracted from included studies and converted into standardised mean differences (SMDs) and ± 95% confidence intervals (CIs). Results Twenty-five studies were used to calculate SMD ± 95% CI. Peak (SMD = 0.815, 95% CI 0.105–1.524, p = 0.024) and mean (SMD = 0.863, 95% CI 0.319–1.406, p = 0.002) velocity, peak (SMD = 0.356, 95% CI 0.057–0.655, p = 0.019) and mean (SMD = 0.692, 95% CI 0.395–0.990, p < 0.001) power, and peak force (SMD = 0.306, 95% CI − 0.028 to 0.584, p = 0.031) favoured CS. Subgroup analyses demonstrated an overall effect for CS across loads (SMD = 0.702, 95% CI 0.548–0.856, p < 0.001), included exercises (SMD = 0.664, 95% CI 0.413–0.916, p < 0.001), experience levels (SMD = 0.790, 95% CI 0.500–1.080, p < 0.001) and CS structures (SMD = 0.731, 95% CI 0.567–0.894, p < 0.001) with no difference within subgroups. Conclusion CSs are a useful strategy to attenuate the loss in velocity, power and peak force during RT and should be used to maintain neuromuscular performance, especially when kinetic outcomes are emphasised. However, it remains unclear if the benefits translate to improved performance across all RT exercises, between sexes and across the lifespan.

High-Intensity Acceleration and Deceleration Demands in Elite Team Sports Competitive Match Play: A Systematic Review and Meta-Analysis of Observational Studies

01-12-2019 – DJ Harper,C Carling,J Kiely

Journal Article, Review

Abstract Background The external movement loads imposed on players during competitive team sports are commonly measured using global positioning system devices. Information gleaned from analyses is employed to calibrate physical conditioning and injury prevention strategies with the external loads imposed during match play. Intense accelerations and decelerations are considered particularly important indicators of external load. However, to date, no prior meta-analysis has compared high and very high intensity acceleration and deceleration demands in elite team sports during competitive match play. Objective The objective of this systematic review and meta-analysis was to quantify and compare high and very high intensity acceleration vs. deceleration demands occurring during competitive match play in elite team sport contexts. Methods A systematic review of four electronic databases (CINAHL, MEDLINE, SPORTDiscus, Web of Science) was conducted to identify peer-reviewed articles published between January 2010 and April 2018 that had reported higher intensity (> 2.5 m·s−2) accelerations and decelerations concurrently in elite team sports competitive match play. A Boolean search phrase was developed using key words synonymous to team sports (population), acceleration and deceleration (comparators) and match play (outcome). Articles only eligible for meta-analysis were those that reported either or both high (> 2.5 m·s−2) and very high (> 3.5 m·s−2) intensity accelerations and decelerations concurrently using global positioning system devices (sampling rate: ≥ 5 Hz) during elite able-bodied (mean age: ≥ 18 years) team sports competitive match play (match time: ≥ 75%). Separate inverse random-effects meta-analyses were conducted to compare: (1) standardised mean differences (SMDs) in the frequency of high and very high intensity accelerations and decelerations occurring during match play, and (2) SMDs of temporal changes in high and very high intensity accelerations and decelerations across first and second half periods of match play. Using recent guidelines recommended for the collection, processing and reporting of global positioning system data, a checklist was produced to help inform a judgement about the methodological limitations (risk of detection bias) aligned to ‘data collection’, ‘data processing’ and ‘normative profile’ for each eligible study. For each study, each outcome was rated as either ‘low’, ‘unclear’ or ‘high’ risk of bias. Results A total of 19 studies met the eligibility criteria, comprising seven team sports including American Football (n = 1), Australian Football (n = 2), hockey (n = 1), rugby league (n = 4), rugby sevens (n = 3), rugby union (n = 2) and soccer (n = 6) with a total of 469 male participants (mean age: 18–29 years). Analysis showed only American Football reported a greater frequency of high (SMD = 1.26; 95% confidence interval CI 1.06–1.43) and very high (SMD = 0.19; 95% CI − 0.42 to 0.80) intensity accelerations compared to decelerations. All other sports had a greater frequency of high and very high intensity decelerations compared to accelerations, with soccer demonstrating the greatest difference for both the high (SMD = − 1.74; 95% CI − 1.28 to − 2.21) and very high (SMD = − 3.19; 95% CI − 2.05 to − 4.33) intensity categories. When examining the temporal changes from the first to the second half periods of match play, there was a small decrease in both the frequency of high and very high intensity accelerations (SMD = 0.50 and 0.49, respectively) and decelerations (SMD = 0.42 and 0.46, respectively). The greatest risk of bias (40% ‘high’ risk of bias) observed across studies was in the ‘data collection’ procedures. The lowest risk of bias (35% ‘low’ risk of bias) was found in the development of a ‘normative profile’. Conclusions To ensure that elite players are optimally prepared for the high-intensity accelerations and decelerations imposed during competitive match play, it is imperative that players are exposed to comparable demands under controlled training conditions. The results of this meta-analysis, accordingly, can inform practical training designs. Finally, guidelines and recommendations for conducting future research, using global positioning system devices, are suggested.

Combat as an Interpersonal Synergy: An Ecological Dynamics Approach to Combat Sports

01-12-2019 – K Krabben,D Orth,J van der Kamp

Journal Article, Review

Abstract In combat sports, athletes continuously co-adapt their behavior to that of the opponent. We consider this interactive aspect of combat to be at the heart of skilled performance, yet combat sports research often neglects or limits interaction between combatants. To promote a more interactive approach, the aim of this paper is to understand combat sports from the combined perspective of ecological psychology and dynamic systems. Accordingly, combat athletes are driven by perception of affordances to attack and defend. Two combatants in a fight self-organize into one interpersonal synergy, where the perceptions and actions of both athletes are coupled. To be successful in combat, performers need to manipulate and take advantage of the (in)stability of the system. Skilled performance in combat sports therefore requires brinkmanship: combatants need to be aware of their action boundaries and purposefully act in meta-stable regions on the limits of their capabilities. We review the experimental literature to provide initial support for a synergetic approach to combat sports. Expert combatants seem able to accurately perceive action boundaries for themselves and their opponent. Local-level behavior of individual combatants has been found to lead to spatiotemporal synchronization at the global level of a fight. Yet, a formal understanding of combat as a dynamic system starting with the identification of order and control parameters is still lacking. We conclude that the ecological dynamics perspective offers a promising approach to further our understanding of skilled performance in combat sports, as well as to assist coaches and athletes to promote optimal training and learning.

Does Acute Fatigue Negatively Affect Intrinsic Risk Factors of the Lower Extremity Injury Risk Profile? A Systematic and Critical Review

29-11-2019 – J Verschueren,B Tassignon,K De Pauw,M Proost,A Teugels,J Van Cutsem,B Roelands,E Verhagen,R Meeusen

Journal Article, Review

Abstract Background Acute fatigue is hypothesized to alter lower extremity injury risk profiles by affecting intrinsic risk factors (i.e. single leg postural control, hamstring strength). However, no systematic overview exists that merges the insights into prospective lower extremity injury risk profiling with the effect of acute fatigue on functional test performance. Objective The objective of this review is to identify the influence of acute fatigue on prospectively determined modifiable intrinsic risk factors for lower extremity injuries. Design Systematic review. Methods PubMed (MEDLINE), Web of Science, PEDro, and Cochrane Library were searched until 29 May 2019. Studies were eligible when the study outcomes encompassed intrinsic modifiable risk factors for lower extremity injury, an acute fatigue intervention, and included healthy athletes or physically active people. Intrinsic modifiable risk factors were identified through recent systematic reviews and meta-analyses, and the referenced original research papers were used to determine outcome measures associated with increased injury risk. Results Forty-three studies reported acute fatigue effects on modifiable risk factors, with eight studies matching all criteria for data-extraction. Acute fatigue can decrease single leg postural control, decrease ankle joint position sense, decrease isokinetic strength of hamstring and quadriceps muscles and can affect isokinetic hamstring:quadriceps ratios. Conclusion Acute fatigue affects prospective intrinsic modifiable risk factors for lower extremity injury, indicating an altered injury risk profile for lateral ankle sprain, patellofemoral pain syndrome and hamstring injuries. Future research should allow for individual fatiguability as a relevant outcome, and merge insights from athlete-centred injury risk profiling and fatigue.

Optimising the ‘Mid-Stage’ Training and Testing Process After ACL Reconstruction

28-11-2019 – M Buckthorpe,F Della Villa

Journal Article, Review

Abstract Outcomes following anterior cruciate ligament (ACL) reconstruction need improving, with poor return-to-sport rates and high risk of secondary re-injury. There is a need to improve rehabilitation strategies after ACL reconstruction, if we can support enhanced patient outcomes. This paper discusses how to optimise the mid-stage rehabilitation process after ACL reconstruction. Mid-stage is a difficult and vitally important stage of the functional recovery process and provides the foundation on which to commence late-stage rehabilitation training. Often many aspects of mid-stage rehabilitation (e.g. knee extensors isolated muscle strength) are not actually restored prior to return-to-sport. In addition, if we are to allow time for optimal late-stage rehabilitation and return-to-sport training, we need to optimise the mid-stage rehabilitation approach and complete it in a timely manner. This paper forms a key part of a strategy to optimise the ACL rehabilitation approach and considers factors more specific to mid-stage rehabilitation characterised in 3 areas: (1) muscle strength: muscle and joint specific, in particular at the knee level, with the knee extensors and flexors and distally with the triceps surae and proximally with the lumbo-pelvic-hip complex, as well as closed kinetic chain strength; (2) altered basic motor patterning (movement quality) and (3) fitness re-conditioning. In addition, the paper provides recommendations on how to implement these into practice, discussing training planning and programming and suggests specific screening to monitor work and when the athlete is able to progress to the next stage (e.g. late-stage rehabilitation criteria).

Reply to Fanton et al.: Comment on “Frequency and Magnitude of Game-Related Head Impacts in Male Contact Sports Athletes: A Systematic Review and Meta-analysis”

25-11-2019 – C Willmott,JV Nguyen,JH Brennan,B Mitra

Letter

Comment on “Frequency and Magnitude of Game-Related Head Impacts in Male Contact Sports Athletes: A Systematic Review and Meta-Analysis”

25-11-2019 – M Fanton,L Wu,D Camarillo

Letter

Physical Activity Interventions for Primary Prevention in Adults: A Systematic Review of Randomized Controlled Trial-Based Economic Evaluations

21-11-2019 – R Mattli,R Farcher,ME Syleouni,S Wieser,N Probst-Hensch,A Schmidt-Trucksäss,M Schwenkglenks

Journal Article, Review

Abstract Background Physical inactivity is a worldwide pandemic associated with major chronic diseases. Given limited resources, policy makers are in need of physical activity interventions that provide best value for money. Objective To summarize evidence from RCT-based economic evaluations of primary prevention physical activity interventions in adult populations outside the workplace setting. Design Systematic review of health economic evaluations. Incremental cost-effectiveness ratios (ICERs) in US$ per MET-hour gained were estimated on the basis of mean differences in intervention costs and standardized effects between intervention and control groups. Data Sources Identification of relevant studies via systematic searches in electronic databases (MEDLINE, Embase and NHSEED). Eligibility Criteria Cost-effectiveness analyses in which all data (except unit costs) came from one RCT investigating physical activity interventions for primary prevention or health promotion in an adult population in high-income countries. Results In twelve eligible studies, 22 interventions were investigated. Interventions were based on advice, goal setting and follow-up support, exercise classes, financial incentives or teaching on behavioral change. The ICER varied widely among the interventions and four interventions showed an ICER below the applied benchmark of US$0.44 to US$0.63 per MET-hour gained. These four interventions were based on individualized advice via print or web. Conclusion We found evidence from RCTs indicating cost-effectiveness of some physical activity interventions for primary prevention in adults. However, the majority of interventions assessed would not be cost-effective according to the benchmark applied. Furthermore, our study showed that trial-based evidence on cost-effectiveness of physical activity interventions is scarce. Therefore, we recommend that future studies investigating the efficacy or effectiveness of such interventions consider costs as an additional outcome and assess cost-effectiveness.