Risk Of Overuse Injuries Research Articles

Epidemiology of Overuse Injuries in US Secondary School Athletics From 2014-2015 to 2018-2019 Using the National Athletic Treatment, Injury and Outcomes Network Surveillance Program.

With 8 million annual US high school student-athletes, the epidemiology of sport-related injuries has garnered significant interest. The most recent studies examining overuse injury rates in high school sports were based on data from 2012 to 2013 and, therefore, may not reflect current overuse injury rates in high school sports. To (1) determine overuse time-loss (TL) and non-time-loss (NTL) injury rates among high school student-athletes using National Athletic Treatment, Injury and Outcomes Network Surveillance Program (NATION-SP) data collected from 2014-2015 to 2018-2019 and (2) compare overuse injury rates based on student-athlete sex defined by whether it was a boys' sport or a girls' sport, the sport itself, and the injury location. Descriptive epidemiology study. Online injury surveillance from 211 high schools (345 individual years of high school data). Athletes who participated in secondary school-sponsored boys' or girls' sports. Boys' and girls' overuse injury data from the NATION-SP during the 2014-2015 to 2018-2019 school years were analyzed. Overuse injuries were identified using a combination of the reported injury mechanism and diagnosis. Time-loss injuries resulted in restriction from participation beyond the day of injury; NTL injuries did not result in restriction from participation beyond the day of injury or involved no lost time due to the injury. Injury counts, rates, and rate ratios (IRRs) were reported with 95% CIs. The total overuse injury rate was 5.3/10 000 athlete-exposures (AEs; 95% CI = 5.1, 5.7), the NTL overuse injury rate was 3.4/10 000 AEs (95% CI = 3.1, 3.6), and the TL overuse injury rate was 2.0/10 000 AEs (95% CI = 1.8, 2.2). The overuse injury rate was greater in girls' sports compared with boys' sports (IRR = 1.9; 95% CI = 1.7, 2.1). The highest rates of overuse injury were observed in girls' cross-country (19.2/10 000 AEs; 95% CI = 15.0, 24.2), girls' track and field (16.0/10 000 AEs; 95% CI = 13.5, 18.8), and girls' field hockey (15.1/10 000 AEs; 95% CI = 10.2, 21.6). Overuse injury rates were higher for the lower extremity than the upper extremity (IRR = 5.7; 95% CI = 4.9, 6.7) and for the lower extremity than the trunk and spine (IRR = 8.9; 95% CI = 7.3, 10.8). Awareness of the overuse injury risk, as well as prevention and intervention recommendations, is necessary and should be specifically targeted at cross-country, field hockey, and track and field athletes.

Knee muscle strength in runners who have had knee surgery: differences between limbs and associations with functional performance

Introduction: Knee muscle weakness has been associated with an increased risk of various overuse injuries in runners and incident knee osteoarthritis; however, little is known about knee strength in runners, particularly those who are at high risk of osteoarthritis who have previously had knee surgery. The aim of this study was to explore differences in knee extensor and flexor strength between surgical and non-surgical limbs in runners with a history of knee surgery, and to explore if knee strength is associated with functional performance. Methods: A convenience sample of 38 runners (run ≥10km/week, ≥3 sessions/week) who had unilateral knee surgery (45% anterior cruciate ligament reconstruction) were recruited (33.2±6.8 years, 11 women). Three maximal voluntary isometric contractions of the knee extensors and flexors were performed at 60° knee flexion (Biodex dynamometer). The highest torque value (Nm) for the knee extensors and flexors for each leg was used for analysis. Functional performance was assessed via three trials of the hop for distance test, with the furthest distance hopped for each leg recorded. Paired t-tests were used to explore differences in knee strength between limbs (whole group and stratified by sex) and partial correlations were used to explore associations between knee strength and hop for distance, controlling for mass, age, and sex. Results: There was no significant difference in knee extensor strength between the surgical and non-surgical limbs (surgical=205.9±53.4Nm, non-surgical=215.5±57.9Nm; p=0.087, Cohen’s d=0.285). A significant difference was observed between limbs for knee flexor strength (surgical=103.6±24.1Nm, non-surgical=112.3±28.6Nm; p=0.001, Cohen’s d=0.576). When examining men only, the same results were found, but there were no significant differences between limbs for women. Small to moderate non-significant associations were observed between knee strength and hop for distance on both the surgical (knee extensor r=0.321, p=0.060; knee flexor r=0.333, p=0.051) and non-surgical limbs (knee extensor r=0.286, p=0.095; knee flexor r=0.093, p=0.596). Discussion: Runners who have had unilateral knee surgery demonstrate knee flexor weakness in the surgical limb, but not knee extensors, although differences may be sex specific. Small to moderate non-significant associations between knee strength and hop for distance indicate that factors other than knee strength may influence functional performance in runners who have had knee surgery. Conflict of interest statement: My co-authors and I acknowledge that we have no conflict of interest of relevance to the submission of this abstract.

Practical Strategies for Integrating Strength and Conditioning Into Early Specialization Sports

ABSTRACT Early sport specialization involves physically immature children participating in intensive year-round training and/or competition for a single sport. The lack of sport exposure and diversification during the developmental years may underlie the increased risk of overuse injuries, blunting of motor skill development, psychosocial issues, overtraining syndrome, burnout, and potential dropout from sport. With increasing number of youth choosing, or being encouraged, to specialize at an early age, we aim to provide evidence-based recommendations for the integration of strength and conditioning into the development programs of young athletes who participate in sports with a culture of early specialization. In addition to the principles of programming, strategies are provided relative to monitoring of growth, maturation, and training load to illustrate the potential complexities of attempting to optimize long-term athletic development in early specializing athletes.

Development of Muscle-Tendon Adaptation in Preadolescent Gymnasts and Untrained Peers: A 12-Month Longitudinal Study.

The current study investigated the effects of long-term athletic training on the development of the triceps surae muscle-tendon unit in preadolescence. Eleven preadolescent untrained children and a group of 21 artistic gymnastics athletes of similar age (9 ± 1.7 yr) and maturity (Tanner stages I and II) participated in the study. The measurements were conducted every 3 months for 1 yr, and training volume and duration of the athletes were documented. Plantar flexor muscle strength, Achilles tendon stiffness, maximum tendon strain, and gastrocnemius medialis morphometrics were measured by integrating kinematics, ultrasonography, and dynamometry. A linear mixed-effects model was used to analyze the investigated parameters. We found greater muscle strength (P < 0.001) in athletes compared with nonathletes but no differences in Achilles tendon stiffness (P = 0.252), indicating a training-induced imbalanced adaptation of muscle strength and tendon stiffness in preadolescent athletes. Although pennation angle (P = 0.490), thickness (P = 0.917), and fascicle length (P = 0.667) did not differ between groups, we found higher fluctuations in pennation angle and muscle strength over 1 yr in athletes. The imbalanced adaptation of muscle strength and tendon stiffness together with greater fluctuations of muscle strength resulted in greater tendon strain fluctuations over 1 yr (P = 0.017) and a higher frequency of athletes with high-level tendon strain (≥9%) compared with nonathletes. The findings indicate an increased mechanical demand for the tendon in preadolescent athletes that could have implications for the risk of tendon overuse injury. Therefore, we recommend the implementation of individual training approaches to preserve a balanced adaptation within the triceps surae muscle-tendon unit in preadolescent athletes.

Risk factors for overuse injuries in a cohort of elite Swedish track and field athletes

BackgroundMost injuries in track and field are caused by overuse with conflicting reports concerning the underlying mechanisms. The purpose of this study was to evaluate how biomechanical and clinical factors relate to the risk of overuse injuries, and to investigate whether the relationships between potential risk factors and injury become stronger if injuries are grouped by location.MethodsThe study is a prospective cohort study conducted during a Swedish track and field season over eleven months, from October to August. The cohort consisted of elite male and female track and field athletes competing in either middle- and long-distance running, sprinting, jumping, or throwing events (n = 96). Athletes performed a baseline screening at enrollment consisting of a clinical examination, running, and strength tests. Injury data was collected during the season by medical professionals and divided according to their anatomical location into upper-body, thigh/hip, knee, or foot/shank injuries.ResultsThirty-four (54.8%) injuries where located at the foot/shank, followed by sixteen injuries at the thigh/hip (25.8%). Only eight knee (12.9%) and four upper-body (6.5%) injuries were registered during the season and therefore not analysed. Effect sizes were calculated for all test variables. Small effect sizes (rpb = .10–.23) were found for eleven risk factors between the overall injured (all injuries combined) and non-injured athletes. By further sub-grouping the injured group into thigh/hip injuries, effect size increased in hip adduction range of motion knee flexion velocity and the muscle flexibility of the iliopsoas. For foot/shank injuries, only the hamstring:quadriceps strength ratios increased for the right side to a small effect size.ConclusionsInjury grouping appears to increase effect size for certain risk factors. Athletes with a slower knee flexion velocity during stance phase were more likely to become injured (p-value <.03, rpb = .37). An increased cohort size to further sub-divide injuries into specific diagnoses is needed.

SPORTS SPECIALIZED YOUTH ATHLETES EXHIBIT LOWER RISK QUALITY OF MOTION THAN NON-SPECIALIZED ADOLESCENTS

Background:Quality of motion and neuromuscular balance are noted predictors of acute injury risk. Early sports specialization and extremely high activity levels have been linked to high risk of injury, especially overuse injury.Purpose:The purpose of this study is to investigate for any relationships between quality of physical movement, quantity of physical activity, and degree of sports specialization in a healthy cohort of children and adolescents.Methods:Healthy children between the ages 10 and 18 completed the HSS Pedi-FABS to assess quantity of physical activity and the Jayanthi scale to assess degree of sports specialization. Quality of motion was assessed using motion analysis sensors (DorsaVi, Kew, Australia) during 5 repetitions of 4 different jumping and squatting motions (Table 1). For each repetition, one point was given for low risk of injury anterior or medial/lateral motion, for a maximum score of 2 per leg. Quality of motion scores were summed for a maximum score of 100 per participant. Specialization level was dichotomized as high specialization with a Jayanthi scale score of 2 or 3 and low specialization with a score of 1 or 2. Independent samples t-tests were used to compare high vs. low specialization participants on physical activity quantity and overall quality of motion. A Pearson correlation was used to determine the relationship between quantity of physical activity and quality of motion.Results:Final analyses included 147 participants (72% male) with a mean age of 13.4 ± 2.2 years. For the entire cohort, the mean Pedi-FABS score was 22.9 ± 6.8, the mean quality score was 25.5 ± 13.5 and 73% were highly specialized. Participants that were highly specialized displayed low risk motion more frequently than participants with low sport specialization (27.6 ± 14.0 vs 19.8 ± 10.1, p < 0.01; Table 2). Highly specialized participants had significantly higher activity levels (24.6 ± 5.9 vs 18.1 ± 6.9, p < 0.001). Additionally, quality of motion was moderately correlated with physical activity level (r = 0.349, p < 0.001).Conclusion:Overall quality of motion as in jump-landing tasks in healthy children was better in highly specialized participants. Taken together with existing literature, although early specialization may put young athletes at risk for overuse injuries, highly sports specialized youth athletes may be at lower risk for acute injury. Future research should explore associations between sports specialization, physical activity, save movement patterns, and athletic injuries.

The Effect of Single Sport Specialization in Youth Sports: A Prospective Cohort Study

Objectives:Large numbers of youth participate in both team and individual sports. In recent years, sports specialization has become increasingly popularized in younger athletes. There is concern that early sports specialization increases the risk of overuse injuries in youth athletes. The purpose of this investigation was to determine the prevalence of sport specialization in youth athletes, and prospectively examine whether specialization correlates with an increased incidence of athletic injury.Methods:895 high school freshman athletes were enrolled starting in 2016, with the intent of following them through the completion of their high school careers. They were recruited from 3 high schools within the same school district. Sports specialization was defined as participating in a single sport in excess of 6 months of the year at the exclusion of other sports. Athletes’ demographic information, sport commitment and injury history were collected through a sports specialization and injury survey. The same athletes were queried again at the conclusion of each season to collect injury information. Athletic training records were used to corroborate, in order to ensure capture of all injuries reported to health care personnel.Results:Of the 895 athletes, 216 (24.1%) reported sport specialization at some point during their high school sports careers. Specialized athletes were exposed to significantly more sports activity (8.41 hours/week vs 7.10 hours/week, p<0.00001 ). They were also much more likely (70.6% vs 25.1%, p< .00001) to compete on a club or travel team for their sport. Male athletes were more likely to specialize than females (27.0% vs 19.3%, p<0.0072). Baseball (12.1% of specialized athletes vs 4.9% of all athletes, p<0.000032) main sport athletes were the only athletes significantly more likely to report specialization. Specialized athletes were significantly more likely than their nonspecialized counterparts to report an injury (39.8% vs 33.2%, p< 0.0271). These athletes suffered from higher severity injuries, requiring more time to recover than their peers. (p<0.0483). Despite the higher propensity for injury in specialized athletes and greater tendency for specialization in males, female athletes were more likely to report injures (p<0.0053). The most common reported injuries were of the knee, ankle, and head (18.6%, 18.2%, 16.6% of all injuries respectively). Season ending injuries were also most commonly knee, ankle, and head injuries (48.5%, 15.2%, 12.1% respectively), with 30.3% of all reported season ending injuries being ACL tears.Conclusions:Specialized student athletes tend to have significantly more injuries than non-specialized athletes, as well as more severe injuries than non-specialized athletes. This is one of the largest and most comprehensive studies to date, evaluating the effect of sports specialization on the incidence of athletic injury in high school athletes.

Pain and body position on the bicycle in competitive and recreational road cyclists: A retrospective study

ABSTRACT This study compared the presence of pain in recreational and competitive road cyclists and body position on the bicycle between cyclists with and without pain. Seventy-one cyclists completed a survey reporting existing cycling-related sites of pain and comfort. Static sagittal and frontal plane images were taken to analyse body position on the bicycle. Participants were separated into recreational and competitive road cycling groups, and further into cyclists reporting pain in the upper body, low back, buttocks/hips and knees for comparison with cyclists without pain. A logistic regression model investigated possible predictors of pain whilst cycling. Pain was present in 67% of recreational and 70% of competitive cyclists whilst comfort was reported by 81% of recreational and 75% of competitive cyclists. Trivial to moderate non-significant differences were observed for body position on the bicycle between cyclists with and without pain, and between cyclists with and without pain in the upper body, low back, buttocks/hips and knees. The predictive logistic model was not significant (p = 0.07) with a model fit predicted by McFadden R2 of 0.07. Given most cyclists reported both pain and comfort, comfort is probably not a good predictor of overuse injury risk.

Internal Mechanics of a Subject-Specific Wrist in the Sagittal versus Dart-Throwing Motion Plane in Adult and Elder Models: Finite Element Analyses

Introduction: Most of the wrist motions occur in a diagonal plane of motion, termed the dart-throwing motion (DTM) plane; it is thought to be more stable compared with movement in the sagittal plane. However, the effect of the altered carpus motion during DTM on the stress distribution at the radiocarpal joint has yet to be explored. Aim: To calculate and compare the stresses between the radius and two carpal bones (the scaphoid and the lunate) in two wrist positions, extension and radial extension (position in DTM), and between an adult and an elder model. Methods: A healthy wrist of a 40-year-old female was scanned using Magnetic Resonance Imaging in two wrist positions (extension, radial extension). The scans were transformed into three-dimensional models and meshed. Finite element (FE) analyses in each position of the wrist were conducted for both adult and elder models, which were differentiated by the mechanical properties of the ligaments. The distal surfaces of the carpal bones articulating with the metacarpals were loaded by physically accurate tendon forces for each wrist position. Results: The von Mises, shear stresses and contact stresses were higher in the extension model compared with the radial-extension model and were higher for the radius-scaphoid interface in the adult model compared with the elder model. In the radius-scaphoid interface, the stress differences between the two wrist positions were smaller in the elder model (11.5% to 22.5%) compared with the adult model (33.6–41.5%). During radial extension, the contact area at the radius-lunate interface was increased, more so in the adult model (222.2%) compared with the elder model (127.9%), while the contact area at the radius-scaphoid was not affected by the position of the wrist in the adult model (100.9%) but decreased in the elder model (50.2%) during radial extension. Conclusion: The reduced stresses during radial extension might provide an explanation to our frequent use of this movement pattern, as the reduced stresses decrease the risk of overuse injury. Our results suggest that this conclusion is relevant to both adults and elder individuals.

Power-assisted Pedicle Screw Technique Protects Against Risk of Surgeon Overuse Injury: A Comparative Electromyography Study of the Neck and Upper Extremity Muscle Groups in a Simulated Surgical Environment.

Cadaveric. The aim of this study was to quantify the amplitude and duration of surgeons' muscle exertion from pedicle cannulation to screw placement using both manual and power-assisted tools in a simulated surgical environment using surface electromyography (EMG). A survey of Scoliosis Research Society members reported rates of neck pain, rotator cuff disease, lateral epicondylitis, and cervical radiculopathy at 3 ×, 5 ×, 10 ×, and 100 × greater than the general population. The use of power-assisted tools in spine surgery to facilitate pedicle cannulation through screw placement during open posterior fixation surgery may reduce torque on the upper limb and risk of overuse injury. Pedicle preparation and screw placement was performed from T4-L5 in four cadavers by two board-certified spine surgeons using both manual and power-assisted techniques. EMG recorded muscle activity from the flexor carpi radialis, extensor carpi radialis, biceps, triceps, deltoid, upper trapezius, and neck extensors. Muscle activity was reported as a percentage of the maximum voluntary exertion of each muscle group (%MVE) and muscle exertion was linked to low- (0-20% MVE), moderate- (20%-45% MVE), high- (45%-70% MVE) and highest- (70%-100% MVE) risk of overuse injury based on literature. Use of power-assisted tools for pedicle cannulation through screw placement maintains average muscle exertion at low risk for overuse injury for every muscle group. Conversely with manual technique, the extensor carpi radialis, biceps, upper trapezius and neck extensors operate at levels of exertion that risk overuse injury for 50% to 92% of procedure time. Powerassisted tools reduce average muscle exertion of the biceps, triceps, and deltoid by upwards of 80%. Power-assisted technique protects against risk of overuse injury. Elevated muscle exertion of the extensor carpi radialis, biceps, upper trapezius, and neck extensors during manual technique directly correlate with surgeons' self-reported diagnoses of lateral epicondylitis, rotator cuff disease, and cervical myelopathy.Level of Evidence: N/A.

Epidemiology of injuries in water board sports: trauma versus overuse injury.

Surfing is an increasingly popular sport in the world, but it is not sufficiently investigated in terms of epidemiology of injuries and possible prevention strategies. Moreover, there are different surfing disciplines, with specific characteristics and therefore different potential risks of injury. The aim of this study was to look at the injuries of recreational surfers in an Italian cohort, distinguishing between trauma and overuse lesions and putting in evidence any difference between specific water board sports. The design is that of a retrospective observational study. An online survey was distributed to a group of Italian surfers that are members of a surfing association. The survey comprised: demographic data, surfing information such as number of sessions per year and years of experience, and surfing injuries story. The sample size consisted of 126 recreational surfers who practiced four different types of surfing: surf, kitesurf, windsurf and stand-up paddle. The incidence of trauma was significantly higher than the incidence of overuse lesions in all four water board sports evaluated (e.g. in surf, 81% for trauma vs. 27% for overuse, with a difference of 55% , P<0.0001). There was a statistically significant effect of the number of surfing sessions per year both for trauma (W=6.36, P=0.0117) and for total injuries (trauma + overuse; W=4.30, P=0.0381), with a 12-times increased risk for the surfers who performed more than 80 sessions per year. The risk of overuse injuries was higher for those who practice surf for more than seven years (P=0.0193). Traumas are more frequent than overuse injuries for all the investigated surfing disciplines. The risk of injury increases as the number of annual sessions and the years of practice increase, demonstrating that experience is not a protective factor, whereas higher exposure is certainly a risk factor. New injury prevention strategies should be based on athletic training and preparation programs, traditionally lacking among recreational surfers.

Psychological risk profile for overuse injuries in sport: An exploratory study

ABSTRACT Overuse injuries account for a substantial part of sport injury incidence among athletes of various sports and levels. Despite the gradual onset of symptoms, athletes often persevere in training and competing. The present exploratory study aimed to identify a psychological risk profile for overuse injury. One hundred and forty-nine athletes competing in various sports responded to a range of questionnaires measuring the following psychological variables: negative life stress, perfectionistic concerns, perfectionistic strivings, athletic identity, and the coach-athlete relationship. Participants subsequently answered the OSTRC Overuse Injury Questionnaire on a weekly basis during a 10-week period. Using a latent profile analysis, athletes were classified into three latent profiles regarding their psychological characteristics. Athletes in the second profile, characterized by a combination of high athletic identity, perfectionistic concerns and negative life stress and poor coach-athlete relationship, were found to be significantly more often affected by overuse injuries (74% of the time) than individuals in the two other profiles (52% and 48% of the time, respectively). In conclusion, psychological factors may contribute to the risk of overuse injuries through complex interactions (i.e. accounting for interdependencies within a specific configuration of variables) rather than through their independent influences.

Jumping with barbell load: Assessment of lower limb joint kinematics and kinetics during landing

Loaded jumps are commonly used to improve leg muscle power. However, the additional load during jump-landing might increase the potential for overuse injury. Therefore, the aims of this study were to evaluate the effect that barbell load has on lower limb joint kinematics and kinetics during jump-landing and to evaluate the effect of arresting the barbell load at flight apex prior to landing on joint kinematic and kinetic variables. Barbell-loaded squat jumps (20, 40, and 60 kg) were investigated during two jump-landing conditions: 1) barbell-loaded (landing with barbell load) and 2) barbell-arrested (barbell load arrested at flight apex prior to jump-landing). Lower body kinematics and joint kinetics were assessed during jump-landing. In the barbell-loaded jump-landing condition, joint angles at initial contact decreased with increasing barbell load. Knee and hip peak power decreased (knee: −38%; hip: −46%), while ankle joint work increased with increasing barbell load. Joint moments, powers and work were decreased in the barbell-arrested condition compared to the barbell-loaded condition. Barbell-loaded jump-landings do not pose increased demands on the knee and the hip joint compared to bodyweight only jump-landings, due to the load-based reductions in jump height and joint kinematic adaptions. However, ankle joint contribution in energy dissipation is increased, possibly resulting in an increased overuse injury risk at this joint. Arresting the barbell load at flight apex prior to jump-landing substantially reduces the joint kinetics, hence serving as valuable training tool for athletes returning to sport after injuries.

Early Sport Specialization Among Former National Collegiate Athletic Association Athletes: Trends, Scholarship Attainment, Injury, and Attrition

Background: Many youth athletes focus on 1 sport to gain a competitive advantage, but early sport specialization may increase risk of overuse injuries and burnout. College athletes have successfully achieved advanced status; therefore, the study of their specialization patterns is a method to assess how specialization affects an athletic career. Purpose: To determine trends in sport specialization by sex, sport, and decade of participation in National Collegiate Athletic Association (NCAA) athletes and assess the effect of specialization on scholarship attainment, injury, and attrition. Study Design: Cohort study; Level of evidence, 3. Methods: An electronic survey was distributed to NCAA athletes who participated from 1960 to 2018. Survey topics included sex, sport, decade of participation, scholarship status, ≥30-day time-loss injuries sustained in college, orthopaedic surgery in college, career length, and age of single-sport specialization. Early specialization was defined as specialization in a single sport before age 15 years. Rates of early specialization were calculated for each sport, sex, individual and team sports, and decade of participation. Rates of scholarship attainment, injury, and attrition were compared between groups. Univariate associations were queried with logistic regression analysis to determine predictors of specialization, scholarship attainment, injury, and early attrition. Results: Of 1550 athletes who participated (17% response rate), 544 (35.1%) were women. Overall, 18.1% of athletes specialized before age 15 years (n = 281). Athletes in gymnastics, tennis, swimming and diving, and soccer were significantly more likely to specialize early, whereas football and baseball athletes were more likely to specialize late (P < .05 for all groups). Early specialization was more common among women (23.4% vs 15.2%; odds ratio, 1.72; P < .01). There was a trend toward earlier specialization for recent college graduates, with graduates from the last decade more likely to be classified as early specialization than those from previous decades (P = .036). Scholarship attainment was overall equivalent between groups. Time-loss injuries, lower extremity injuries, and orthopaedic surgery in college were not statistically different between groups. Career lengths were similar, but burnout was more common among early specialization athletes (10.5% vs 7.0%; odds ratio, 3.76; P < .01). Conclusion: Less than one-fifth of NCAA athletes surveyed specialized before age 15 years, and neither scholarship attainment nor time-loss injury rate was affected by early specialization. Early specialization is on the rise but is associated with increased burnout.

Monitoring Practices of Training Load and Biological Maturity in UK Soccer Academies.

Overuse injury risk increases during periods of accelerated growth, which can subsequently impact development in academy soccer, suggesting a need to quantify training exposure. Nonprescriptive development scheme legislation could lead to inconsistent approaches to monitoring maturity and training load. Therefore, this study aimed to communicate current practices of UK soccer academies toward biological maturity and training load. Forty-nine respondents completed an online survey representing support staff from male Premier League academies (n = 38) and female Regional Talent Clubs (n = 11). The survey included 16 questions covering maturity and training-load monitoring. Questions were multiple-choice or unipolar scaled (agreement 0-100) with a magnitude-based decision approach used for interpretation. Injury prevention was deemed highest importance for maturity (83.0 [5.3], mean [SD]) and training-load monitoring (80.0 [2.8]). There were large differences in methods adopted for maturity estimation and moderate differences for training-load monitoring between academies. Predictions of maturity were deemed comparatively low in importance for bio-banded (biological classification) training (61.0 [3.3]) and low for bio-banded competition (56.0 [1.8]) across academies. Few respondents reported maturity (42%) and training load (16%) to parent/guardians, and only 9% of medical staff were routinely provided this data. Although consistencies between academies exist, disparities in monitoring approaches are likely reflective of environment-specific resource and logistical constraints. Designating consistent and qualified responsibility to staff will help promote fidelity, feedback, and transparency to advise stakeholders of maturity-load relationships. Practitioners should consider biological categorization to manage load prescription to promote maturity-appropriate dose-responses and to help reduce the risk of noncontact injury.

Monitoring Muscle-Tendon Adaptation Over Several Years of Athletic Training and Competition in Elite Track and Field Jumpers.

Differences in muscle and tendon responsiveness to mechanical stimuli and time courses of adaptive changes may disrupt the interaction of the musculotendinous unit (MTU), increasing the risk for overuse injuries. We monitored training-induced alterations in muscle and tendon biomechanical properties in elite jumpers over 4 years of athletic training to detect potential non-synchronized adaptations within the triceps surae MTU. A combined cross-sectional and longitudinal investigation over 4 years was conducted by analyzing triceps surae MTU mechanical properties in both legs via dynamometry and ultrasonography in 67 elite track and field jumpers and 24 age-matched controls. Fluctuations in muscle and tendon adaptive changes over time were quantified by calculating individual residuals. The cosine similarity of the relative changes of muscle strength and tendon stiffness between sessions served as a measure of uniformity of adaptive changes. Our cross-sectional study was unable to detect clear non-concurrent differences in muscle strength and tendon stiffness in elite jumpers. However, when considering the longitudinal data over several years of training most of the jumpers demonstrated greater fluctuations in muscle strength and tendon stiffness and hence tendon strain compared to controls, irrespective of training period (preparation vs. competition). Moreover, two monitored athletes with chronic Achilles tendinopathy showed in their affected limb lower uniformity in MTU adaptation as well as higher fluctuations in tendon strain over time. Habitual mechanical loading can affect the MTU uniformity in elite jumpers, leading to increased mechanical demand on the tendon over an athletic season and potentially increased risk for overuse injuries.

Intra-Segment Coordination Variability in Road Cyclists during Pedaling at Different Intensities

Background: The purpose of this study is to examine the lower extremity intra-segment coordination and variability of road cyclists during pedaling at different intensities. Methods: Eleven semi-professional road cyclists perform four trials at workloads of 50%, 75%, 100%, and 125% of their maximum power output in a randomized order. Thigh, shank, and foot range of motions (ROM) and the coordination and variability of these segments are compared across different pedaling intensities. Results: Foot ROM in the sagittal plane and shank ROM in the transverse plane are significantly different between different pedaling intensities. Moreover, specific coupling patterns and variabilities are observed across the pedaling cycle; however, they were not significantly different across different pedaling intensities in four pedaling phases. Conclusion: The results highlight the role of knee extensors and plantar flexors during the first and second half of the propulsion phase of pedaling, respectively. Thigh abduction dominancy with faster movement compared to the shank indicates a more valgus stress during the propulsive phase of pedaling, which can increase the risk of overuse injuries in the knee. Moreover, the smaller variability during the transition between the propulsive and recovery phases indicates a reduction in degrees of freedom and may increase the risk of overuse injuries.

Can the Open Stance Forehand Increase the Risk of Hip Injuries in Tennis Players?

Background:The open stance forehand has been hypothesized by tennis experts (coaches, scientists, and clinicians) to be more traumatic than the neutral stance forehand as regards hip injuries in tennis. However, the influence of the forehand stance (open or neutral) on hip kinematics and loading has not been assessed.Purpose:To compare the kinematics and kinetics at the hip joint during 3 common forehand stances (attacking neutral stance [ANS], attacking open stance [AOS], defensive open stance [DOS]) in advanced tennis players to determine whether the open stance forehand induces higher hip loading.Study Design:Descriptive laboratory study.Methods:The ANS, AOS, and DOS forehand strokes of 8 advanced right-handed tennis players were recorded with an optoelectronic motion capture system. The flexion-extension, abduction-adduction, and external-internal rotation angles as well as intersegmental forces and torques of the right hip were calculated using inverse dynamics.Results:The DOS demonstrated significantly higher values than both the ANS and AOS for anterior (P < .001), medial (P < .001), and distractive (P < .001) forces as well as extension (P = .004), abduction (P < .001), and external rotation (P < .001) torques. The AOS showed higher distractive forces than the ANS (P = .048). The DOS showed more extreme angles of hip flexion (P < .001), abduction (P < .001), and external rotation (P = .010).Conclusion:The findings of this study imply that the DOS increased hip joint angles and loading, thus potentially increasing the risk of hip overuse injuries. The DOS-induced hip motion could put players at a higher risk of posterior-superior hip impingement compared with the ANS and AOS.Clinical Relevance:Coaches and clinicians with players who have experienced hip pain or sustained injuries should encourage them to use a more neutral stance and develop a more aggressive playing style to avoid the DOS, during which hip motion and loading are more extreme.

Detraining of specific neuromuscular qualities in elite footballers during COVID-19 quarantine

ABSTRACT The COVID-19 pandemic forced elite football leagues into extended breaks followed by prompt resumption of competition. Inadequate periods of on-pitch football-specific training may underlie the increased injury incidence reported following restart in a non-peer reviewed report. Detraining effects from isolated training are expected, but existing models do not completely describe the unprecedented conditions imposed by COVID-19. Providing insight into specific neuromuscular qualities affected by extended absence of football-specific training, we share countermovement jump performance and kinetic data from an elite team’s assessments pre and post 15 weeks of isolated training, and to contextualise these trends, off-season changes with no training. The isolated circuit resistance and aerobic interval training maintained jump height and Reactive Strength Indexmodified, but there were moderate magnitude (p = 0.01–0.04) changes in eccentric ‘yielding’ and landing ‘loading’ phase variables. These changes suggest a compromised initiation of countermovement deceleration, impact attenuation and altered coordination/motor control strategies or muscle-tendon properties. This analysis may have revealed kinetic markers specifically stimulated by football-specific training/competition, relevant to post-quarantine monitoring. Lower landing forces may reduce overuse injury risk, while yielding phase alterations suggest a negative effect on reactive performance, therefore the overall effect on vulnerability to injury is unclear.

Training for the HandbikeBattle: an explorative analysis of training load and handcycling physical capacity in recreationally active wheelchair users

Purpose (1) to analyze training characteristics of recreationally active wheelchair users during handcycle training, and (2) to examine the associations between training load and change in physical capacity. Methods Former rehabilitation patients (N = 60) with health conditions such as spinal cord injury or amputation were included. Participants trained for five months. A handcycling/arm crank graded exercise test was performed before and after the training period. Outcomes: peak power output per kg (POpeak/kg) and peak oxygen uptake per kg (VO2peak/kg). Training load was defined as Training Impulse (TRIMP), which is rating of perceived exertion (sRPE) multiplied by duration of the session, in arbitrary units (AU). Training intensity distribution (TID) was also determined (time in zone 1, RPE ≤4; zone 2, RPE 5–6; zone 3, RPE ≥7). Results Multilevel regression analyses showed that TRIMPsRPE was not significantly associated with change in physical capacity. Time in zone 2 (RPE 5–6) was significantly associated with ΔVO2peak, %ΔVO2peak, ΔVO2peak/kg and %ΔVO2peak/kg. Conclusion Training at RPE 5–6 was the only determinant that was significantly associated with improvement in physical capacity. Additional controlled studies are necessary to demonstrate causality and gather more information about its usefulness, and optimal handcycle training regimes for recreationally active wheelchair users. IMPLICATIONS FOR REHABILITATION Monitoring of handcycle training load is important to structure the training effort and intensity over time and to eventually optimize performance capacity. This is especially important for relatively untrained wheelchair users, who have a low physical capacity and a high risk of overuse injuries and shoulder pain. Training load can be easily calculated by multiplying the intensity of the training (RPE 0–10) with the duration of the training in minutes. Results on handcycle training at RPE 5–6 intensity in recreationally active wheelchair users suggests to be promising and should be further investigated with controlled studies.