The Relationship Between Undulatory Underwater Kick Performance Determinants and Underwater Velocity in Competitive Swimmers: A Systematic Review.

BACKGROUND: Undulatory underwater swimming (UUS) has become an integral component of the start and turn phases in competitive swimming allowing higher velocities than can be achieved swimming at the surface. An understanding of the most important determinants for UUS performance and how these can be optimised to different swimmers is poorly understood. OBJECTIVE: The aim of this systematic review was to systematically assess the current peer-reviewed literature on the relationship between UUS performance determinants and underwater velocity in competitive swimmers. METHODS: An electronic search using AusSportMed, Embase, PubMed, SPORTDiscus and Biomechanics and Medicine in Swimming was performed. The methodological quality of the studies was evaluated using a biomechanics-specific checklist developed by Hindle and colleagues (Sports Med Open. 5(1):49, 2019. 10.1186/s40798-019-0222-z ). RESULTS: Twenty-five studies met the eligibility criteria. While UUS velocity was nearly perfectly related (r > 0.90) to foot resultant acceleration and kick frequency, several other biomechanical factors were also significant correlates. UUS velocity and frequency were typically higher in high-performance swimmers and during prone versus dorsal positions. UUS velocity, kick frequency and kick amplitude were also significantly correlated with high angular velocities of the hip, knee and ankle joints and knee range of motion. CONCLUSION: While there appears to be evidence supporting some performance variables to be related to UUS, future research should examine how to optimise the kinematic and kinetic characteristics with respect to the imposed task constraints and organism constraints between swimmers. Additional research should also investigate the effect of biomechanically informed interventions to improve UUS performance. REGISTRATION: Open Science Framework.

'Such a massive part of rehab is between the ears'; barriers to and facilitators of anterior cruciate ligament reconstruction rehabilitation: a qualitative focus group analysis.

BACKGROUND: Current evidence demonstrates that few patients complete anterior cruciate ligament reconstruction rehabilitation according to evidence-based guidelines. It is important to investigate the viewpoints of our patients to identify patient-reported barriers and facilitators of anterior cruciate ligament reconstruction rehabilitation. Qualitative analysis can provide insight into potential methods for improving the delivery of rehabilitation services. METHODS: In this qualitative study, utilising a social constructionism orientation, viewed through the social phenomenological lens, three focus groups were conducted with individuals 1-20 years post anterior cruciate ligament reconstruction (n = 20, 9 males, 11 females, mean 6.5 years post-surgery, 19-51 years old). Utilising a semi-structured interview guide, participants were asked about their experiences during anterior cruciate ligament reconstruction rehabilitation. Focus groups were recorded, transcribed, and coded using an inductive semantic thematic analysis methodology. RESULTS: Five organising themes were identified (consisting of 19 sub-themes) to provide a framework to present the data: psychological, physiological, rehabilitation service, rehabilitation characteristics, and interaction with others. Each theme details aspects of rehabilitation, such as exercise delivery, informational support, frequency, and duration of care, kinesiophobia, weight management and interactions with teams and coaches, which present barriers or facilitators for patients to adhere to and participate in rehabilitation. Example quotes are provided for each theme to provide context and the patient's voice. CONCLUSIONS: This qualitative investigation identified key aspects of a patient's rehabilitation in which they encounter a variety of barriers and facilitators of ACL reconstruction rehabilitation. These aspects, such as the rehabilitation characteristics, service delivery, psychological and physiological factors, and interactions with others, were consistently identified by this cohort as factors which affected their rehabilitation. The themes may provide targets for clinicians to improve rehabilitation and deliver patient-centred care. However, the themes must be evaluated in future trials to assess whether interventions to remove barriers or enhance facilitators improves subsequent outcomes such as return to sport and re-injury rates.

Application of Leg, Vertical, and Joint Stiffness in Running Performance: A Literature Overview.

Stiffness, the resistance to deformation due to force, has been used to model the way in which the lower body responds to landing during cyclic motions such as running and jumping. Vertical, leg, and joint stiffness provide a useful model for investigating the store and release of potential elastic energy via the musculotendinous unit in the stretch-shortening cycle and may provide insight into sport performance. This review is aimed at assessing the effect of vertical, leg, and joint stiffness on running performance as such an investigation may provide greater insight into performance during this common form of locomotion. PubMed and SPORTDiscus databases were searched resulting in 92 publications on vertical, leg, and joint stiffness and running performance. Vertical stiffness increases with running velocity and stride frequency. Higher vertical stiffness differentiated elite runners from lower-performing athletes and was also associated with a lower oxygen cost. In contrast, leg stiffness remains relatively constant with increasing velocity and is not strongly related to the aerobic demand and fatigue. Hip and knee joint stiffness are reported to increase with velocity, and a lower ankle and higher knee joint stiffness are linked to a lower oxygen cost of running; however, no relationship with performance has yet been investigated. Theoretically, there is a desired "leg-spring" stiffness value at which potential elastic energy return is maximised and this is specific to the individual. It appears that higher "leg-spring" stiffness is desirable for running performance; however, more research is needed to investigate the relationship of all three lower limb joint springs as the hip joint is often neglected. There is still no clear answer how training could affect mechanical stiffness during running. Studies including muscle activation and separate analyses of local tissues (tendons) are needed to investigate mechanical stiffness as a global variable associated with sports performance.

The biomechanical characteristics of the strongman atlas stone lift.

BACKGROUND: The atlas stone lift is a popular strongman exercise where athletes are required to pick up a large, spherical, concrete stone and pass it over a bar or place it on to a ledge. The aim of this study was to use ecologically realistic training loads and set formats to (1) establish the preliminary biomechanical characteristics of athletes performing the atlas stone lift; (2) identify any biomechanical differences between male and female athletes performing the atlas stone lift; and (3) determine temporal and kinematic differences between repetitions of a set of atlas stones of incremental mass. METHODS: Kinematic measures of hip, knee and ankle joint angle, and temporal measures of phase and repetition duration were collected whilst 20 experienced strongman athletes (female: n = 8, male: n = 12) performed three sets of four stone lifts of incremental mass (up to 85% one repetition maximum) over a fixed-height bar. RESULTS: The atlas stone lift was categorised in to five phases: the recovery, initial grip, first pull, lap and second pull phase. The atlas stone lift could be biomechanically characterised by maximal hip and moderate knee flexion and ankle dorsiflexion at the beginning of the first pull; moderate hip and knee flexion and moderate ankle plantarflexion at the beginning of the lap phase; moderate hip and maximal knee flexion and ankle dorsiflexion at the beginning of the second pull phase; and maximal hip, knee extension and ankle plantarflexion at lift completion. When compared with male athletes, female athletes most notably exhibited: greater hip flexion at the beginning of the first pull, lap and second pull phase and at lift completion; and a shorter second pull phase duration. Independent of sex, first pull and lap phase hip and ankle range of motion (ROM) were generally smaller in repetition one than the final three repetitions, while phase and total repetition duration increased throughout the set. Two-way interactions between sex and repetition were identified. Male athletes displayed smaller hip ROM during the second pull phase of the first three repetitions when compared with the final repetition and smaller hip extension at lift completion during the first two repetitions when compared with the final two repetitions. Female athletes did not display these between-repetition differences. CONCLUSIONS: Some of the between-sex biomechanical differences observed were suggested to be the result of between-sex anthropometric differences. Between-repetition differences observed may be attributed to the increase in stone mass and acute fatigue. The biomechanical characteristics of the atlas stone lift shared similarities with the previously researched Romanian deadlift and front squat. Strongman athletes, coaches and strength and conditioning coaches are recommended to take advantage of these similarities to achieve greater training adaptations and thus performance in the atlas stone lift and its similar movements.

The Biomechanical Characteristics of the Strongman Yoke Walk.

The yoke walk is a popular strongman exercise where athletes carry a heavily loaded frame balanced across the back of their shoulders over a set distance as quickly as possible. The aim of this study was to use ecologically realistic training loads and carry distances to (1) establish the preliminary biomechanical characteristics of the yoke walk; (2) identify any biomechanical differences between male and female athletes performing the yoke walk; and (3) determine spatiotemporal and kinematic differences between stages (intervals) of the yoke walk. Kinematic and spatiotemporal measures of hip and knee joint angle, and mean velocity, stride length, stride rate and stance duration of each 5 m interval were taken whilst 19 strongman athletes performed three sets of a 20 m yoke walk at 85% of their pre-determined 20 m yoke walk one repetition maximum. The yoke walk was characterised by flexion of the hip and slight to neutral flexion of the knee at heel strike, slight to neutral extension of the hip and flexion of the knee at toe-off and moderate hip and knee range of motion (ROM), with high stride rate and stance duration, and short stride length. Between-interval comparisons revealed increased stride length, stride rate and lower limb ROM, and decreased stance duration at greater velocity. Although no main between-sex differences were observed, two-way interactions revealed female athletes exhibited greater knee extension at toe-off and reduced hip ROM during the initial (0-5 m) when compared with the final three intervals (5-20 m), and covered a greater distance before reaching maximal normalised stride length than males. The findings from this study may better inform strongman coaches, athletes and strength and conditioning coaches with the biomechanical knowledge to: provide athletes with recommendation on how to perform the yoke walk based on the technique used by experienced strongman athletes; better prescribe exercises to target training adaptations required for improved yoke walk performance; and better coach the yoke walk as a training tool for non-strongman athletes.

Inertial-Based Human Motion Capture: A Technical Summary of Current Processing Methodologies for Spatiotemporal and Kinematic Measures.

Inertial-based motion capture (IMC) has been suggested to overcome many of the limitations of traditional motion capture systems. The validity of IMC is, however, suggested to be dependent on the methodologies used to process the raw data collected by the inertial device. The aim of this technical summary is to provide researchers and developers with a starting point from which to further develop the current IMC data processing methodologies used to estimate human spatiotemporal and kinematic measures. The main workflow pertaining to the estimation of spatiotemporal and kinematic measures was presented, and a general overview of previous methodologies used for each stage of data processing was provided. For the estimation of spatiotemporal measures, which includes stride length, stride rate, and stance/swing duration, measurement thresholding and zero-velocity update approaches were discussed as the most common methodologies used to estimate such measures. The methodologies used for the estimation of joint kinematics were found to be broad, with the combination of Kalman filtering or complimentary filtering and various sensor to segment alignment techniques including anatomical alignment, static calibration, and functional calibration methods identified as being most common. The effect of soft tissue artefacts, device placement, biomechanical modelling methods, and ferromagnetic interference within the environment, on the accuracy and validity of IMC, was also discussed. Where a range of methods have previously been used to estimate human spatiotemporal and kinematic measures, further development is required to reduce estimation errors, improve the validity of spatiotemporal and kinematic estimations, and standardize data processing practices. It is anticipated that this technical summary will reduce the time researchers and developers require to establish the fundamental methodological components of IMC prior to commencing further development of IMC methodologies, thus increasing the rate of development and utilisation of IMC.

Rehabilitation characteristics and patient barriers to and facilitators of ACL reconstruction rehabilitation: A cross-sectional survey.

OBJECTIVES: To investigate patient-reported rehabilitation characteristics and barriers to and facilitators of ACL reconstruction rehabilitation. DESIGN: Survey-based study. SETTING: Online survey platform. PARTICIPANTS: Adults 1-20 years post ACL reconstruction (n = 304). MAIN OUTCOME MEASURES: 1) rehabilitation characteristics, 2) barriers to and facilitators of rehabilitation. RESULTS: Fear of re-injury (43.8%) was the highest rating barrier to rehabilitation adherence, while a good relationship with your rehabilitation provider was regarded as the most important factor (83.6%) in facilitating rehabilitation. Rehabilitation frequency reduced across the duration of rehabilitation from most commonly 1 x week (38.2%) in the first three months to once every month (26%) from 6 to 9 months. Almost all participants (95.7%) consulted a rehabilitation provider for the first six months. Only 43.4% of respondents returned to their previous level of sport. The exploratory analysis identified that low barriers to rehabilitation and a longer duration of supervised rehabilitation are associated with a faster return to sport, greater likelihood of return to previous level of sport and fewer reported ongoing problems with the knee. CONCLUSIONS: This cross-sectional survey provides insight into the patient's experience of rehabilitation practices and a patient's perspective on the key barriers to and facilitators of ACL rehabilitation adherence and participation.

Validation of Spatiotemporal and Kinematic Measures in Functional Exercises Using a Minimal Modeling Inertial Sensor Methodology.

This study proposes a minimal modeling magnetic, angular rate and gravity (MARG) methodology for assessing spatiotemporal and kinematic measures of functional fitness exercises. Thirteen healthy persons performed repetitions of the squat, box squat, sandbag pickup, shuffle-walk, and bear crawl. Sagittal plane hip, knee, and ankle range of motion (ROM) and stride length, stride time, and stance time measures were compared for the MARG method and an optical motion capture (OMC) system. The root mean square error (RMSE), mean absolute percentage error (MAPE), and Bland-Altman plots and limits of agreement were used to assess agreement between methods. Hip and knee ROM showed good to excellent agreement with the OMC system during the squat, box squat, and sandbag pickup (RMSE: 4.4-9.8°), while ankle ROM agreement ranged from good to unacceptable (RMSE: 2.7-7.2°). Unacceptable hip and knee ROM agreement was observed for the shuffle-walk and bear crawl (RMSE: 3.3-8.6°). The stride length, stride time, and stance time showed good to excellent agreement between methods (MAPE: (3.2 ± 2.8)%-(8.2 ± 7.9)%). Although the proposed MARG-based method is a valid means of assessing spatiotemporal and kinematic measures during various exercises, further development is required to assess the joint kinematics of small ROM, high velocity movements.

The Influence, Barriers to and Facilitators of Anterior Cruciate Ligament Rehabilitation Adherence and Participation: a Scoping Review.

BACKGROUND: Outcomes following anterior cruciate ligament (ACL) reconstruction are considered poor. There are many factors which may influence patient outcomes. As such, the purpose of this review was to report on the influence, barriers to and facilitators of rehabilitation adherence and participation after ACL reconstruction, providing information to help clinicians and patients make quality decisions to facilitate successful rehabilitation. METHODS: A systematic search of five electronic databases was undertaken in identifying studies from inception to 18 July 2019. The search included English language articles reporting on the influence, barriers to and facilitators of adherence and participation in rehabilitation of patients who have undergone ACL reconstruction. Data extraction and synthesis of included studies were undertaken. RESULTS: Full text articles (n = 180) were assessed for eligibility following screening of titles and abstracts (n = 1967), yielding 71 studies for inclusion. Forty-four articles investigated 'rehabilitation prescription and participation' and 36 articles investigated 'rehabilitation barriers and facilitators'. The results indicate that a moderately or minimally supervised rehabilitation program is at least as effective as a fully supervised high-frequency rehabilitation program, although a longer duration of supervised rehabilitation is associated with improvement in a multitude of functional outcomes. A number of psychological factors associated with rehabilitation adherence were also identified. The most commonly investigated concepts were self-motivation, athletic identity and social support. Patients perceived the therapeutic relationship, interaction with family and friends, self-motivation, fear of reinjury, organisation/lack of time and interpersonal comparison as the most common barriers to and facilitators of rehabilitation. CONCLUSIONS: A longer duration of supervised rehabilitation is associated with an increased chance of meeting functional and return to sport criteria; however, the optimal supervised rehabilitation frequency is yet to be determined. Identification of the barriers to and facilitators of adherence and participation in ACL rehabilitation provides an opportunity for further research to be conducted to address personal, environmental and treatment-related factors, with the aim to improve rehabilitation outcomes.

An individualised approach to assess the sidestep manoeuvre in male rugby union athletes.

OBJECTIVES: This study aimed to (1) quantitatively assess external knee abduction moments between legs, and (2) qualitatively assess anterior cruciate ligament injury risk between group mean and individual athlete data during the sidestep manoeuvre. DESIGN: Descriptive cross-sectional study. METHODS: Sixteen male academy-level rugby union athletes (20.4±2.7yr; 186.3±9.1cm; 99.1±14.4kg) performed three maximal effort sidesteps (>6.0ms-1) on each leg. Three-dimensional motion analysis was used to obtain external knee abduction moments, wherein the two legs were separated by the preferred and non-preferred kicking leg. Quantitative comparisons were made between legs, while qualitative comparisons were made been group mean and individual athlete data. RESULTS: When sidestepping on the non-preferred leg, athletes produced 25% greater knee abduction moments (ES=0.43) and presented modified postural adjustments associated with injury risk (extended knee [ES=-0.26; -8%], more trunk lateral flexion [ES=0.42; 17%] and more distance between the centre-of-mass and ankle-joint-centre of the stance leg [ES=0.97; 11%]) compared to the preferred leg. Individually, only 9 out of 16 athletes presented a higher abduction moment in their non-preferred leg with individual asymmetries ranging between 2.2 and 47%. CONCLUSIONS: Nearly half of the athletes assessed in this study showed the potential to "slip under the radar" when using the group mean for assessment. When assessing athletes for anterior cruciate ligament injury risk factors, individual athlete data should be examined in conjunction with the group mean for a more holistic view of the data.

Correction to: The biomechanics and applications of strongman exercises: a systematic review.

The original article [1] contained an error whereby the symbol '☼' originally included in and below Tables 2-5 did not display properly.

A systematic review of the biomechanical research methods used in strongman studies.

As the sport of strongman is becoming increasingly popular, and such exercises are being commonly used by strength and conditioning coaches for a wide range of athletic groups, a greater understanding of the biomechanics of strongman exercises is warranted. To improve the quality of research, this systematic review summarised the research methodology used in biomechanical studies of strongman exercises and identified potential improvements to current approaches. A search of 5 databases found 10 articles adherent to the pre-defined inclusion criteria. The studies assessed 8 strongman exercises and included male participants of relatively similar body mass but varying training backgrounds. Due to the complexity of strongman exercises and the challenges in collecting advanced biomechanical data in the field, most studies used simplified measurement/analysis methods (e.g., 2D motion capture). Future strongman biomechanical studies should: assess under/un-researched strongman exercises; include a greater number of experienced and female strongman athletes; utilise more advanced (e.g., 3D motion capture and/or inertial sensor) technology so to provide a broader range and greater quality of data. Such approaches will provide strength and conditioning coaches, strongman coaches and athletes with a greater understanding of strongman exercises, thereby further improving exercise prescription, athlete performance and minimising risk of injury.

Effects of upper and lower body wearable resistance on spatio-temporal and kinetic parameters during running.

Wearable resistance training involves added load attached directly to the body during sporting movements. The effects of load position during running are not yet fully established. Therefore, the purpose of this research was to determine spatio-temporal and kinetic characteristics during submaximal running using upper, lower and whole-body wearable resistance (1-10% body mass (BM)). Twelve trained male runners completed eight 2-min treadmill running bouts at 3.9 m/s with and without wearable resistance. The first and last bouts were unloaded, while the middle 6 were randomised wearable resistance conditions: upper body (UB) 5% BM, lower body (LB) 1%, 3%, 5% BM and whole body (WB) 5%, 10% BM. Wearable resistance of 1-10% BM resulted in a significant increase in heart rate (5.40-8.84%), but minimal impact on spatio-temporal variables. Loads of 5% BM and greater caused changes in vertical stiffness, vertical and horizontal force, and impulse. Functional and effective propulsive force (2.95%, 2.88%) and impulse (3.40%, 3.38%) were significantly (p < 0.05) greater with LB5% than UB5%. Wearable resistance may be used to increase muscular kinetics during running without negatively impacting spatio-temporal variables. The application of these findings will vary depending on athlete goals. Future longitudinal studies are required to validate training contentions.

The Biomechanics and Applications of Strongman Exercises: a Systematic Review.

BACKGROUND: The sport of strongman is becoming increasingly popular, catering for females, lightweight, and Masters competitors, with strongman exercises also being used by strength and conditioning coaches for a range of athletic groups. Thus, a systematic review was conducted to examine researchers' current understanding of the biomechanics of strongman exercises, with a view to improve strongman athlete performance, provide biomechanical evidence supporting the transferability of strongman exercises to strength and conditioning/rehabilitation programs, and identify gaps in the current knowledge of the biomechanics of strongman exercises. METHODS: A two-level search term strategy was used to search five databases for studies relevant to strongman exercises and biomechanics. RESULTS: Eleven articles adherent to the inclusion criteria were returned from the search. The studies provided preliminary biomechanical analysis of various strongman exercises including the key biomechanical performance determinants of the farmer's walk, heavy sled pull, and tire flip. Higher performing athletes in the farmer's walk and heavy sled pull were characterized by a greater stride length and stride rate and reduced ground contact time, while higher performing athletes in the tire flip were characterized by a reduced second pull phase time when compared with lower performing athletes. Qualitative comparison of carrying/walking, pulling and static lifting strongman, traditional weight training exercises (TWTE), and common everyday activities (CEA), like loaded carriage and resisted sprinting, were discussed to further researchers' understanding of the determinants of various strongman exercises and their applications to strength and conditioning practice. A lack of basic quantitative biomechanical data of the yoke walk, unilateral load carriage, vehicle pull, atlas stone lift and tire flip, and biomechanical performance determinants of the log lift were identified. CONCLUSIONS: This review has demonstrated the likely applicability and benefit of current and future strongman exercise biomechanics research to strongman athletes and coaches, strength and conditioning coaches considering using strongman exercises in a training program, and tactical operators (e.g., military, army) and other manual labor occupations. Future research may provide a greater understanding of the biomechanical determinants of performance, potential training adaptations, and risks expected when performing and/or incorporating strongman exercises into strength and conditioning or injury rehabilitation programs.

Using stiffness to assess injury risk: comparison of methods for quantifying stiffness and their reliability in triathletes.

BACKGROUND: A review of the literature has indicated that lower body stiffness, defined as the extent to which the lower extremity joints resists deformation upon contact with the ground, may be a useful measure for assessing Achilles injury risk in triathletes. The nature of overuse injuries suggests that a variety of different movement patterns could conceivably contribute to the final injury outcome, any number and combination of which might be observed in a single individual. Measurements which incorporate both kinetics and kinematics (such as stiffness) of a movement may be better able to shed light on individuals at risk of injury, with further analysis then providing the exact mechanism of injury for the individual. Stiffness can be measured as vertical, leg or joint stiffness to model how the individual interacts with the environment upon landing. However, several issues with stiffness assessments limit the effectiveness of these measures to monitor athletes' performance and/or injury risk. This may reflect the variety of common biomechanical stiffness calculations (dynamic, time, true leg and joint) that have been used to examine these three stiffness levels (vertical, leg and joint) across a variety of human movements (i.e. running or hopping) as well as potential issues with the reliability of these measures, especially joint stiffness. Therefore, the aims of this study were to provide a comparison of the various methods for measuring stiffness during two forms of human bouncing locomotion (running and hopping) along with the measurement reliability to determine the best methods to assess links with injury risk in triathletes. METHODS: Vertical, leg and joint stiffness were estimated in 12 healthy male competitive triathletes on two occasions, 7 days apart, using both running at 5.0 ms-1 and hopping (2.2 Hz) tasks. RESULTS: Inter-day reliability was good for vertical (ICC = 0.85) and leg (ICC = 0.98) stiffness using the time method. Joint stiffness reliability was poor when assessed individually. Reliability was improved when taken as the sum of the hip, knee and ankle (ICC = 0.86). The knee and ankle combination provided the best correlation with leg stiffness during running (Pearson's Correlation = 0.82). DISCUSSION: The dynamic and time methods of calculating leg stiffness had better reliability than the "true" method. The time and dynamic methods had the best correlation with the different combinations of joint stiffness, which suggests that they should be considered for biomechanical screening of triathletes. The knee and ankle combination had the best correlation with leg stiffness and is therefore proposed to provide the most information regarding lower limb mechanics during gait in triathletes.

The effect of ankle bracing on landing biomechanics in female netballers.

OBJECTIVES: Investigate the impact of lace-up ankle braces on landing biomechanics. DESIGN: Within-subject repeated measures. Participants completed a drop jump, drop land, and netball-specific task in braced and unbraced conditions. SETTING: Biomechanical research laboratory. PARTICIPANTS: Twenty female high school netballers. MAIN OUTCOME MEASURES: Leg, knee, and ankle stiffness, knee/ankle stiffness ratio, knee and ankle sagittal excursion, peak vertical ground reaction force, time-to-peak vertical ground reaction force, and loading rate. RESULTS: In the brace condition leg stiffness increased bilaterally during the drop land (ES = 0.21, 0.22), ankle stiffness increased bilaterally during the drop jump (ES = 0.37, 0.29) and drop land (ES = 0.40, 0.60), and knee/ankle stiffness ratio decreased in all three tasks (ES = -0.22 to -0.45). Ankle sagittal excursion decreased bilaterally during the drop jump (ES = -0.35, -0.53) and drop land (ES = -0.23, -0.46), and decreased in the lead limb during the netball jump (ES = -0.36). Knee excursion decreased bilaterally during the drop jump (ES = -0.36, -0.40) and in the lead limb during netball task (ES = -0.59). Lead limb TTP was greater during the netball jump (ES = 0.41). CONCLUSIONS: Lace-up ankle braces may increase leg and joint stiffness and reduce joint excursion during landing but do not appear to affect landing forces. The observed effect on landing biomechanics may predispose young netballers to injury.

Stiffness as a Risk Factor for Achilles Tendon Injury in Running Athletes.

BACKGROUND: Overuse injuries are multifactorial resulting from cumulative loading. Therefore, clear differences between normal and at-risk individuals may not be present for individual risk factors. Using a holistic measure that incorporates many of the identified risk factors, focusing on multiple joint movement patterns may give better insight into overuse injuries. Lower body stiffness may provide such a measure. OBJECTIVE: To identify how risk factors for Achilles tendon injuries influence measures of lower body stiffness. METHODS: SPORTDiscus, Web of Science, CINAHL and PubMed were searched for Achilles tendon injury risk factors related to vertical, leg and joint stiffness in running athletes. RESULTS: Increased braking force and low surface stiffness, which were clearly associated with increased risk of Achilles tendon injuries, were also found to be associated with increased lower body stiffness. High arches and increased vertical and propulsive forces were protective for Achilles tendon injuries and were also associated with increased lower body stiffness. Risk factors for Achilles tendon injuries that had unclear associations were also investigated with the evidence trending towards an increase in leg stiffness and a decrease in ankle stiffness being detrimental to Achilles tendon health. CONCLUSION: Few studies have investigated the link between lower body stiffness and Achilles injury. High stiffness is potentially associated with risk factors for Achilles tendon injuries although some of the evidence is controversial. Prospective injury studies are needed to confirm this relationship. Large amounts of high-intensity or high-speed work or running on soft surfaces such as sand may increase Achilles injury risk. Coaches and clinicians working with athletes with new or reoccurring injuries should consider training practices of the athlete and recommend reducing speed or sand running if loading is deemed to be excessive.

Recreational Snow-Sports Injury Risk Factors and Countermeasures: A Meta-Analysis Review and Haddon Matrix Evaluation.

BACKGROUND: Snow sports (alpine skiing/snowboarding) would benefit from easily implemented and cost-effective injury prevention countermeasures that are effective in reducing injury rate and severity. OBJECTIVE: For snow sports, to identify risk factors and to quantify evidence for effectiveness of injury prevention countermeasures. METHODS: Searches of electronic literature databases to February 2014 identified 98 articles focused on snow sports that met the inclusion criteria and were subsequently reviewed. Pooled odds ratios (ORs) with 90% confidence intervals (CIs) and inferences (percentage likelihood of benefit/harm) were calculated using data from 55 studies using a spreadsheet for combining independent groups with a weighting factor based on quality rating scores for effects. RESULTS: More experienced skiers and snowboarders are more likely to sustain an injury as a result of jumps, while beginners sustain injuries primarily as a result of falls. Key risk factors that countermeasure interventions should focus on include, beginner skiers (OR 2.72; 90% CI 2.15-3.44, 99% most likely harmful), beginner snowboarders (OR 2.66; 90% CI 2.08-3.40, 99% harmful), skiers/snowboarders who rent snow equipment (OR 2.58; 90% CI 1.98-3.37, 99% harmful) and poor visibility due to inclement weather (OR 2.69; 90% CI 1.43-5.07, 97% harmful). Effective countermeasures include helmets for skiers/snowboarders to prevent head injuries (OR 0.58; 90% CI 0.51-0.66, 99% most likely beneficial), and wrist guards for snowboarders to prevent wrist injuries (OR 0.33; 90% CI 0.23-0.47, 99% beneficial). DISCUSSION: The review identified key risk factors for snow-sport injuries and evaluated the evidence for the effectiveness of existing injury prevention countermeasures in recreational (general public use of slopes, not racing) snow sports using a Haddon's matrix conceptual framework for injury causation (host/snow-sport participant, agent/mechanism and environment/community). CONCLUSION: Best evidence for the effectiveness of injury prevention countermeasures in recreational snow sports was for the use of helmets and wrist guards and to address low visibility issues via weather reports and signage.

Achilles tendon injury risk factors associated with running.

BACKGROUND: Research into the nature of overuse Achilles tendon injuries is extensive, yet uncertainty remains around how to identify athletes susceptible to Achilles tendon injury. OBJECTIVE: To identify the strength of evidence for biomechanical risk factors associated with Achilles tendon injuries. RESEARCH METHODS: SPORTDiscus, CINAHL, Web of Science and PubMed were searched for Achilles tendon injury risk factors and biomechanical measures which are altered in runners with Achilles tendon injuries, excluding ruptures. Fifteen articles were included in the analysis. RESULTS: Two variables, high vertical forces and high arch, showed strong evidence for reduced injury risk. High propulsive forces and running on stiffer surfaces may also be protective. Only one biomechanical variable, high braking force, showed clear evidence for increasing Achilles injury risk. DISCUSSION: Gait retraining to direct the centre of mass further forward to reduce high braking force could be useful in decreasing the risk of Achilles injury. The majority of biomechanical risk factors examined showed unclear results, which is likely due to the multifactorial nature of Achilles overuse injuries. Many risk factors are related to how the athlete's body interacts with the environment during gait, including ground reaction forces, muscle activity both prior to landing and immediately post ground contact, and joint motion throughout stance. CONCLUSION: Multiple risk factors have been associated with the development of Achilles tendon injuries in running athletes but most effects remain unclear. Advice for athletes recovering from Achilles tendon injuries could include avoiding soft surfaces and reducing the pace of recovery runs. Orthotic intervention could assist athletes with low arches but modification of pronation should be viewed with caution. Strength training and gait retraining could be beneficial for reducing injury risk.