Baseline clinical and MRI risk factors for hamstring reinjury showing the value of performing baseline MRI and delaying return to play: a multicentre, prospective cohort of 330 acute hamstring injuries.

OBJECTIVES: Studies identifying clinical and MRI reinjury risk factors are limited by relatively small sample sizes. This study aimed to examine the association between baseline clinical and MRI findings with the incidence of hamstring reinjuries using a large multicentre dataset. METHODS: We merged data from four prospective studies (three randomised controlled trials and one ongoing prospective case series) from Qatar and the Netherlands. Inclusion criteria included patients with MRI-confirmed acute hamstring injuries (<7 days). We performed multivariable modified Poisson regression analysis to assess the association of baseline clinical and MRI data with hamstring reinjury incidence within 2 months and 12 months of follow-up. RESULTS: 330 and 308 patients were included in 2 months (31 (9%) reinjuries) and 12 months (52 (17%) reinjuries) analyses, respectively. In the 2-month analysis, the presence of discomfort during the active knee extension test was associated with reinjury risk (adjusted risk ratio (ARR) 3.38; 95% CI 1.19 to 9.64). In the 12 months analysis, the time to return to play (RTP) (ARR 0.99; 95% CI 0.97 to 1.00), straight leg raise angle on the injured leg (ARR 0.98; 95% CI 0.96 to 1.00), the presence of discomfort during active knee extension test (ARR 2.52; 95% CI 1.10 to 5.78), the extent of oedema anteroposterior on MRI (ARR 0.74; 95% CI 0.57 to 0.96) and myotendinous junction (MTJ) involvement on MRI (ARR 3.10; 95% CI 1.39 to 6.93) were independently associated with hamstring reinjury. CONCLUSIONS: Two clinical findings (the presence of discomfort during active knee extension test, lower straight leg raise angle on the injured leg), two MRI findings (less anteroposterior oedema, MTJ involvement) and shorter time to RTP were independently associated with increased hamstring reinjury risk. These findings may assist the clinician to identify patients at increased reinjury risk following acute hamstring injury. TRIAL REGISTRATION NUMBERS: NCT01812564; NCT02104258; NL2643; NL55671.018.16.

DYNEELAX Robotic Arthrometer Reliability and Feasibility on Healthy and Anterior Cruciate Ligament Injured/Reconstructed Persons.

Background: Anterior cruciate ligament (ACL) injuries are commonly assessed using clinical examination and magnetic resonance imaging, but these methods have limitations in reproducibility and quantification. Instrumented laxity measurements using devices, like the DYNEELAX®, offer an alternative approach. However, to date, there is no human data on the DYNEELAX® and the reliability of these devices remains a subject of debate, and there is no consensus on appropriate knee tightening levels for testing. We hypothesized that the DYNEELAX®, with standardized knee tightening, would provide reliable measurements of knee laxity in adult volunteers. Methods: This prospective cohort study involved 48 pain-free adult volunteers. Laxity measurements were taken using a robotic-type motorized instrument (DYNEELAX®) on two separate occasions, at least 1 h and no more than 8 h apart, with knee tightening forces of 90 N ± 5 N. Metrics of anterior tibial translation and internal/external tibial axial rotations were recorded. Results: The device displayed excellent intrarater reliability for all the metrics, with intraclass correlation coefficients ranging from 0.91 to 0.96. Anterior translation exhibited the highest reliability (intraclass correlation coefficient = 0.96), with a minimum detectable change of 0.83 mm. Conclusions: DYNEELAX® is reliable in measuring knee laxity in adult volunteers when using standardized stabilizing knee tightening forces of 90 ± 5 N. The most sensitive measurement parameters (in terms of minimum detectable change as a proportion of the observed range) were anterior translation (in mm) at 150 N and secondary compliance.

Causal inference did not detect any effect of jump load on knee complaints in elite men's volleyball.

The aim was to determine how jump load affects knee complaints in elite men's volleyball. We collected data from four men's premier league volleyball teams through three seasons in a prospective cohort study (65 players, 102 player-seasons). Vert inertial measurement devices captured the jump load (jump frequency and jump height) from 21 088 daily player sessions, and knee complaints were reported in 3568 weekly OSTRC-O questionnaires. Mixed complementary log-log regression models described the probability of (i) experiencing symptoms if players were currently asymptomatic, (ii) worsening symptoms if players had symptoms, and (iii) recovery from knee complaints. Based on our causal assumptions, weekly jump load was modeled as the independent variable, adjusted for age (years), weight (kg), position on volleyball team, and past jump load. No certain evidence of an association was found between weekly jump load and probability of (i) knee complaints (p from 0.10 to 0.32 for three restricted cubic splines of load), (ii) worsening symptoms if the player already had symptoms (p from 0.11 to 0.97), (iii) recovery (p from 0.36 to 0.63). The probability of knee complaints was highest for above-average weekly jump load (~1.2% for an outside hitter with mean age and height) compared with low loads (~1%) and very high loads (→ ~ 0%). The association between jump load and knee complaints risk remains unclear. Small differences in risk across observed jump load levels were observed. It would likely require substantially increased sample sizes to detect this association with certainty.

Acute clinical evaluation for the diagnosis of lateral ankle ligament injuries is useful: A comparison between the acute and delayed settings.

PURPOSE: To determine the diagnostic value of seven injury history variables, nine clinical tests (including the combination thereof) and overall clinical suspicion for complete discontinuity of the lateral ankle ligaments in the acute (0-2 days post-injury) and delayed setting (5-8 days post-injury). METHODS: All acute ankle injuries in adult athletes (≥18 years) presenting up to 2 days post-injury were assessed for eligibility. Athletes were excluded if imaging studies demonstrated a frank fracture or 3 T MRI could not be acquired within 10 days post-injury. Using standardized history variables and clinical tests, acute clinical evaluation was performed within 2 days post-injury. Delayed clinical evaluation was performed 5-8 days post-injury. Overall, clinical suspicion was recorded after clinical evaluation. MRI was used as the reference standard. RESULTS: Between February 2018 and February 2020, a total of 117 acute ankle injuries were screened for eligibility, of which 43 were included in this study. Complete discontinuity of lateral ankle ligaments was observed in 23 (53%) acute ankle injuries. In the acute setting, lateral swelling had 100% (95% confidence interval [CI]: 82-100) sensitivity, haematoma had 85% (95% CI: 61-96) specificity and the anterior drawer test had 100% (95% CI: 77-100) specificity. In the delayed setting, sensitivity for the presence of haematoma improved from 43% (95% CI: 24-65) to 91% (95% CI: 70-98; p < 0.01) and the sensitivity of the anterior drawer test improved from 21% (95% CI: 7-46) to 61% (95% CI: 39-80; p = 0.02). Clinical suspicion had a positive likelihood ratio (LR) of 4.35 (95% CI: 0.55-34.17) in the acute setting and a positive LR of 6.09 (95% CI: 1.57-23.60) in the delayed setting. CONCLUSIONS: In the acute setting, clinical evaluation can exclude complete discontinuity (e.g., absent lateral swelling) and identify athletes with a high probability of complete discontinuity (e.g., positive anterior drawer test) of the lateral ankle ligaments. In the delayed setting, the sensitivity of common clinical findings increases resulting in an improved diagnostic accuracy. In clinical practice, this study underlines the importance of meticulous clinical evaluation in the acute setting. LEVEL OF EVIDENCE: Level III.

Knee, Low Back, and Shoulder Problems Among University and Professional Volleyball Players: Playing With Pain.

CONTEXT: The knee, low back, and shoulder account for most overuse injuries in volleyball. Previous researchers have used methodology that did not examine the extent of injury burden and effect on performance. OBJECTIVE: To develop a more accurate and complete understanding regarding the weekly prevalence and burden of knee, low back, and shoulder problems within the highest levels of men's volleyball, including the role that preseason complaints, match participation, player position, team, and age have on complaints. DESIGN: Descriptive epidemiology study. SETTING: Professional volleyball clubs and the National Collegiate Athletic Association Division I program. PATIENTS OR OTHER PARTICIPANTS: A total of 75 male volleyball players, representing 4 teams playing in their country's respective premier league (Japan, Qatar, Turkey, and the United States), participated over a 3-season period. MAIN OUTCOME MEASURE(S): Players completed a weekly questionnaire (Oslo Sports Trauma Research Centre Overuse Injury Questionnaire) reporting pain related to their sport and the extent to which knee, low back, and shoulder problems affected participation, training volume, and performance. Problems leading to moderate or severe reductions in training volume or performance or the inability to participate were considered substantial problems. RESULTS: The mean weekly prevalence of knee, low back, and shoulder problems based on 102 player-seasons was 31% (95% CI = 28%, 34%), 21% (95% CI = 18%, 23%), and 19% (95% CI = 18%, 21%), respectively. Most players (93%, 95/102 player-seasons) reported some level of knee (79%, n = 81/102 player-seasons), low back (71%, n = 72/102 player-seasons), or shoulder (67%, n = 68/102 player-seasons) complaints during the season. Most players (58%, n = 59/102 player-seasons) experienced at least 1 episode of substantial problems affecting the knee (33%, n = 34/102 player-seasons), low back (27%, n = 28/102 player-seasons), or shoulder (27%, n = 28/102 player-seasons). Players with preseason complaints had more in-season complaints than teammates without preseason problems (mean weekly prevalence: knee, 42% versus 8%, t49 = -18.726, P < .001; low back, 34% versus 6%, t32 = -12.025, P < .001; shoulder, 38% versus 8%, t30 = -10.650, P < .001). CONCLUSION: Nearly all included elite male volleyball players experienced knee, low back, or shoulder problems, and most had at least 1 bout that substantially reduced training participation or sport performance. These findings suggest that knee, low back, and shoulder problems result in greater injury burden than previously reported.

Quadriceps strength, patellar tendon quality, relative load exposure, and knee symptoms in male athletes before the anterior cruciate ligament reconstruction.

Introduction: Anterior cruciate ligament (ACL) injuries cause knee instability, knee pain, weight-bearing adjustments, and functional deficits but their association to patellar tendon quality is unknown. Our purpose was to investigate quadriceps strength, patellar tendon quality, relative load exposure, perceived knee stability, knee pain, extension angle, and time from ACL injury; in addition to examining their relative associations. Methods: Injured and uninjured legs of 81 male athletes of different sports with a unilateral ACL injury (18-45 years) were examined. Participants reported location and intensity of knee pain and their perceived stability using a numerical rating scale (NRS 0-10). Strength was tested with an isokinetic device. Tendon quality was measured using ultrasound tissue characterization. Means ± standard deviation (SD) of perceived knee stability, knee extension angle, knee pain, isokinetic quadriceps strength in relation to body mass, proportion of echo-types (I-IV), tendon volume, and number of days from ACL injury to assessment are reported. Values of effect sizes (ES) and correlations (rs) were calculated. Results: ACL injured leg demonstrated reduced reported knee stability (6.3 ± 2.5), decreased knee extension angle (-0.7 ± 3.1° vs. -2.7 ± 2.2°; ES = 0.7; P < 0.001), greater knee pain (NRS 3.1 ± 2.2 vs. 0.0 ± 0.1; ES = 2.0; P < 0.001), and 22% lower quadriceps strength (228.0 ± 65.0 vs. 291.2 ± 52.9 Nm/kg: ES = 1.2; P < 0.001) as compared to the uninjured leg. However, patellar tendons in both legs displayed similar quality. Quadriceps strength was associated with stability (rs = -0.54; P < 0.001), pain (rs = -0.47; P < 0.001), extension angle (rs = -0.39; P < 0.001), and relative load exposure (rs = -0.34; P < 0.004). Echo-types distribution was beneficially associated with time from ACL injury (rs range: -0.20/ -0.32; P < 0.05). Discussion: ACL injured athletes displayed knee pain, extension deficit, and weaker quadriceps in the injured leg. While there were no differences in patellar tendon quality between legs, longer time from ACL injury showed better tendon quality.

Eccentric hamstring strength in young athletes is best documented when normalised to body mass: A cross-sectional study with normative data of 590 athletes from different age categories.

Despite its widespread use in adults, the Nordic hamstring exercise remains underexplored in athletic youth populations. Further, given the dynamic nature of growth and maturation, comparisons with elite adult populations may be inaccurate. Here we describe absolute and body mass-normalised eccentric hamstring normative values for football, athletics and multi-sport youth populations. 676 routine standardised tests were conducted, including 244 U12-U18 student-athletes (football, athletics, multi-sport) and 346 Qatar Stars League (QSL) football players using the NordBord. The average maximum values for the left and right leg from 3 repetitions were recorded. Significant increases in absolute strength were seen across chronological (e.g., 150 N ± 15 for U12 to 330 N ± 40 for U18) and skeletal (142.9 N ± 13.9 for skeletal age of 12 compared to 336.2 N ± 71.2 for skeletal age of 18) age groups. The differences in values normalised to body mass were smaller at 3.6 N/kg ± 0.25 for the U-13 group, but similar for the U14 to U18 groups (4.5 N/kg ± 0.16, 4.6 N/kg ± 0.11, 4.6 N/kg ± 0.27, 4.7 N/kg ± 0.14, 4.5 N/kg ± 0.18). Students displayed lower absolute strength than the professional football players (272.1 N compared to 297.3 N, p < 0.0001) but higher relative strength (4.7 N/kg compared to 4.2 N/kg, p < 0.0001). Comparing Nordic hamstring strength values between athletes, and between skeletal and chronological age groups can be done when values are normalised to the athlete's body mass. For the U14s and onwards age categories, body mass normalised values are comparable to professional football players.

Medical services at the FIFA world cup Qatar 2022.

OBJECTIVE: The Football World Cup is among the biggest sporting events in the world, but data to inform the requirements of medical care for such tournaments are limited. This study describes the athlete and team medical services at the FIFA World Cup Qatar 2022 . METHODS: Three different medical service entities were identified through a needs analysis based on expert advice, team physician interviews and questionnaires prior to the event: 'Team Services' to provide any workforce or equipment needs of the teams, a 'Polyclinic' to manage any acute medical demands, and a 'recovery centre' to improve game readiness throughout the tournament. All services had been set up prior to the tournament and thoroughly tested. RESULTS: Of a total of 832 athletes, ~1300 team delegation and ~130 match officials, 167 individuals including 129 (77%) athletes and 38 (23%) non-athletes were assessed in the polyclinic. For the 129 athletes (median 4 players per team), medical imaging was the most requested service, which peaked during the group phase of the tournament. Most requests were received during normal working hours despite many games finishing late at night. 30 of the 32 participating teams solicited medical services for their players at least once. Three teams made use of the recovery facilities, and 17 teams requested additional medical equipment or clinical assistance. CONCLUSION: Central imaging services was the most used medical resource at the FIFA World Cup Qatar 2022, and over half of teams required additional medical equipment or personnel. These data may inform planning of medical services for similar events in the future.

The MyJump App is a Valid Method of Assessing and Classifying Limb Symmetry During Recovery from Anterior Cruciate Ligament Reconstruction.

Background: Jump testing performance and limb symmetry measures are important metrics for clinicians to monitor during rehabilitation after Anterior Cruciate Ligament (ACL) reconstruction, however they require hardware and software which is not commonly available in clinical practice. Video-based solutions may present a feasible alternative, but their veracity in classifying patients using limb-symmetry of 90% has not been established, nor have the clinimetric values for the performance measures been reported in this population. Purpose: To describe the diagnostic accuracy (pass/fail using 90% LSI) and clinimetrics of an iPad-based app ("MyJump") compared to reference force plate analyses for limb symmetry, jump/hop height, contact time, flight time, and reactive strength index. Study design: Prospective cohort, diagnostic accuracy. Methods: Fifty-one consecutive patients recovering from ACL reconstruction undertaking routine independent clinical evaluation of their hop and jump performance were concurrently and independently examined using force plates and the MyJump app. Diagnostic accuracy of MyJump was compared to reference force plate analyses using a criterion of 90% limb symmetry. Results: Diagnostic accuracy of the MyJump app was very good: positive predictive value for jump height was 0.83 and 1.0 for reactive strength index, and negative predictive value was 0.95 and 1.0 for the same metrics, respectively. Of the 131 classifications made using the MyJump app, there were five false positives and three false negatives - all of these were in classification of jump height with no misclassifications of RSI. Irrespective of jump type, the MyJump app displayed excellent reliability (ICC>0.95) for both height and reactive strength index. Minimum detectable changes were approximately 1cm for height, 0.1 for reactive strength index, 0.02s for contact time, and 0.3s for flight time. Conclusion: Where force plates are unavailable, the MyJump app is a valid and reliable substitute for criteria assessment of jump/hop height and reactive strength index in those recovering from ACL surgery using a 90% limb symmetry threshold. The minimum detectable changes vary by metric but are likely sufficiently accurate to detect clinical changes. Level Of Evidence: Level 3.

Shoulder pain and injury risk factors in competitive swimmers: A systematic review.

AIM: To synthesize and assess the literature for shoulder pain and injury risk factors in competitive swimmers. DESIGN: Systematic review with best-evidence synthesis. DATA SOURCES: CINHAL, SportDiscus, Scorpus, PubMed, and Embase databases from 1966 to April 30 2022. SEARCH AND INCLUSION: Cohort, cross-sectional, and case-control studies investigating shoulder pain or injury risk factors in competitive swimmers were included. Quality of eligible studies were assessed using a modified Newcastle-Ottawa scale. Risk factors were divided into four categories: modifiable-intrinsic, modifiable-extrinsic, non-modifiable, and other/secondary. RESULTS: Of 1356 studies identified, 24 full texts were evaluated for methodological quality, 22 met the criteria and were included in best evidence synthesis. There was no strong evidence supporting or refuting the association between 80 assessed variables and shoulder injury or pain. The swimmers' competitive level (nondirectional), and shoulder muscle recruitment profiles (e.g., increased activity of serratus anterior) exhibited moderate evidence supporting an association. Conversely, internal and external range of motion, middle finger back scratch test, training frequency, specialty stroke, height/weight, sex, and age all had moderate evidence opposing an association. Limited evidence was found for 58 variables, and conflicting for 8. The highest quality study (n = 201) suggested high acute-to-chronic workload ratio and reduced posterior shoulder strength endurance are associated with injury. CONCLUSIONS: Due to the paucity of high-quality studies, future prospective studies are needed to reevaluate known risk factor associations over exploring additional potential risk factors. Swimming practitioners should be aware of the nondirectional association of a swimmer's competitive level and pain, as squad changes could impact injury incidence. Moreover, swimmers experiencing shoulder pain may show increased activity in shoulder stabilizers during specific movements. Importantly, shoulder strength-endurance may be the most clinically relevant modifiable intrinsic risk factor.

In-Game Workload Demands of Position Players in Major League Baseball.

BACKGROUND: Athletes who are well prepared for the physical demands of competition are less susceptible to injury. Defining and then preparing athletes for these in-game demands is critical to athlete health and performance. The injury burden within Major League Baseball (MLB) is significant and differs by position. Despite its importance, the workload demands have not been described for position players in MLB. HYPOTHESIS: That running demands would be significantly higher for outfielders, followed by infielders, and catchers, respectively, while batting and baserunning metrics would be similar across positions. STUDY DESIGN: Cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: Total and high-speed running distance (>75% Vmax), high-speed running count, hard accelerations (>2.78 m/s/s), defensive and baserunning minutes, total and hard throws (>75% max), and bat swing counts were calculated from Statcast data. Players with 100 games or more in the 2018 season (n = 126) were included for analysis. RESULTS: All offensive and baserunning metrics were similar across positions; however, significant positional differences were observed for defensive and overall workload metrics. High-speed running was highest among outfielders (F1,7 = 27.1, P < 0.01), followed by infielders, then catchers. Hard accelerations (F1,7 = 12.9, P < 0.01) were highest among first basemen, then outfielders, remaining infielders, and catchers. Total throws (F1,7 = 17.7, P < 0.01) were highest among middle infielders. Hard throws (P < 0.01) were highest among shortstops and third basemen. CONCLUSION: In-game workloads differ significantly by defensive position in MLB. These differences in running, throwing, and hitting volumes have significant implications for physical preparation and injury return-to-play progressions to optimize performance and minimize injury and reinjury risk for these athletes. CLINICAL RELEVANCE: These data provide insight into how best to prepare athletes of different positions for the demands of the game both in terms of preseason preparation as well as return-to-play benchmarks following injury. These data should also serve as a platform for future research into the relationship between workload and injury among professional baseball players.

Performance and symmetry measures during vertical jump testing at return to sport after ACL reconstruction.

OBJECTIVE: Vertical jump tests are more sensitive in revealing asymmetries in performance metrics at the time of return to sport after anterior cruciate ligament (ACL) reconstruction (ACLR) than horizontal hop tests. However, it remains unclear which vertical tests (bilateral or unilateral) and which metrics (kinetics or performance) are most effective in informing the rehabilitation status and readiness for return to sport. We aimed to investigate the status of athletes during vertical jump testing at return to sport after ACLR. METHODS: A dual force platform system was used to evaluate jumping performance of 126 recreational and professional athletes at the time of return to sport after ACLR, as well as 532 healthy control participants. Performance and kinetic metrics were collected during four jump tests: double-leg countermovement jump, single-leg countermovement jump, double-leg 30 cm drop jump and single-leg 15 cm drop jump. Between-limb and between-group differences were explored using mixed models analyses. RESULTS: At the time of return to sport after ACLR, athletes still presented significant differences favouring the uninvolved side, particularly in the symmetry of the concentric impulse (p<0.001) in all jumps compared with the control group. Peak landing force asymmetry was greater in the ACLR group than the controls during the countermovement (p<0.001, MD=-11.6; 95% CI -15.4 to -7.9) and the double-leg drop jump (p=0.023, MD=-8.9; 95% CI -14.9 to -2.8). The eccentric impulse asymmetry was significantly greater (p=0.018, MD=-3.8; 95% CI -5.8 to -1.7) in the ACLR group during the single-leg drop jump only. Jump height was significantly lower (p<0001) in the ACLR group compared with controls in all tests except the double-leg drop jump. CONCLUSION: At the time of return to sport after ACLR, despite passing the traditional discharge criteria, athletes remained asymmetrical during all vertical jump tests, in the concentric (push-off) phase, during landing from bilateral jumps and for most performance metrics. Clinicians should aim to restore not only symmetry in ground reaction forces but also absolute performance metrics such as jump height, reactive strength index and contact times, to potentially reduce injury risk and improve overall athletic performance.

Mechanisms of ACL injuries in men's football: A systematic video analysis over six seasons in the Qatari professional league.

To assess the mechanisms of ACL injury in male professional football players in Qatar across multiple seasons using systematic video analysis. 15 ACL injuries occurred in competition among the professional football teams that participated in an injury Surveillance Programme during 6 seasons (2013/2014 to 2018/2019). High-definition broadcast videos of these injuries were analyzed (49 views; 34 slow motion) by five analysts who independently described the injury mechanisms (situation, behavior, biomechanical characteristics) using validated observational tools. A knee valgus mechanism was observed in two-thirds of the cases (1 with direct contact to the knee, 3 with indirect contact (other body parts) and 6 with no contact). No visible valgus was reported in 2 of the direct knee contact injuries, while 3 cases of non-contact and indirect contact injuries were unclear. We observed 4 main categories of injury situation among those (n = 12) classified as non-contact/ indirect contact (multiple combinations were possible): pressing (n = 6), tackling or being tackled (n = 4), blocking (n = 3) and screening (n = 2). Direct contact injuries (n = 3) were suffered by 2 players during tackling and 1 whilst being tackled. Contact injuries represented only 20% of ACL injuries occurring during competition in Qatari professional soccer players. Independent of the playing situation, knee valgus was frequently observed (10/15 cases). Pressing was the most common situation (6/15 cases) leading to injury. Landing after heading was not reported in any of these ACL injuries.

Shoulder Range of Motion Measurements and Baseball Elbow Injuries: Ambiguity in Scientific Models, Approach, and Execution is Hurting Overhead Athlete Health.

Elbow injuries are a significant and increasing issue in baseball. Elbow injuries account for 16% of all injuries sustained at the professional level and collegiate level. Because of the continued rise in injury rates, loss of performance value, and medical burden, sports medicine clinicians have attempted to research the causes underlying this injury epidemic in an attempt to help mitigate baseball elbow injuries. Shoulder range of motion (ROM) is the most researched clinical metric related to elbow injuries in baseball and has the greatest consensus as a viable prognostic factor specifically for medial elbow injury. Shoulder ROM is easy to measure, can be modified through stretching and manual therapy interventions, and can be easily assessed during preseason screening throughout all baseball levels. Despite a large number of studies and the widespread use of shoulder ROM in injury risk screening, current findings are unclear as to whether there is a true cause-effect relation with baseball elbow injuries. We argue that the conflicting findings revolving around the value of shoulder ROM measurements associated with baseball elbow injuries are the result of 4 gaps in the research approaches implemented to date: ambiguous research questions, mixed study populations, statistical models used, and shoulder ROM methodology. Specifically, there is a mismatch of methods, statistical models, and conclusions such as (1) investigating the association (i.e., correlation) between shoulder ROM measurements and injury and (2) investigating the cause-effect relation of shoulder ROM to baseball injuries. The purpose of this article is to detail the required scientific steps to evaluate whether preseason shoulder ROM is a potential causal factor for pitching elbow injury. We also provide recommendations to allow for future causal inferences to be made between shoulder ROM and elbow injury. This information will ultimately assist in informing clinical models of care and decision making for baseball throwers.

The effects of upper body blood flow restriction training on muscles located proximal to the applied occlusive pressure: A systematic review with meta-analysis.

BACKGROUND: Blood flow restriction combined with low load resistance training (LL-BFRT) is associated with increases in upper limb muscle strength and size. The effect of LL-BFRT on upper limb muscles located proximal to the BFR cuff application is unclear. OBJECTIVE: The aim of this systematic review was to evaluate the effect of LL-BFRT compared to low load, or high load resistance training (LL-RT, HL-RT) on musculature located proximal to cuff placement. METHODS: Six electronic databases were searched for randomized controlled trials (RCTs). Two reviewers independently evaluated the risk of bias using the PEDro scale. We performed a meta-analysis using a random effects model, or calculated mean differences (fixed-effect) where appropriate. We judged the certainty of evidence using the GRADE approach. RESULTS: The systematic literature searched yielded 346 articles, of which 9 studies were eligible. The evidence for all outcomes was of very low to low certainty. Across all comparisons, a significant increase in bench press and shoulder flexion strength was found in favor of LL-BFRT compared to LL-RT, and in shoulder lean mass and pectoralis major thickness in favor of the LL-BFRT compared to LL-RT and HL-RT, respectively. No significant differences were found between LL-BFRT and HL-RT in muscle strength. CONCLUSION: With low certainty LL-BFRT appears to be equally effective to HL-RT for improving muscle strength in upper body muscles located proximal to the BFR stimulus in healthy adults. Furthermore, LL-BFRT may induce muscle size increase, but these adaptations are not superior to LL-RT or HL-RT.

The load borne by the Achilles tendon during exercise: A systematic review of normative values.

The Achilles tendon (AT) can be exposed to considerable stress during athletic activities and is often subject to pathologies such as tendinopathies. When designing a prevention or rehabilitation protocol, mechanical loading is a key factor to consider. This implies being able to accurately determine the load applied to the AT when performing exercises that stress this tendon. A systematic review was performed to synthesize the load borne by the AT during exercises/activities. Three databases (Pubmed, Embase and Cochrane) were searched for articles up to May 2021, and only the studies assessing the AT load in newtons relative to body-weight (BW) on humans during activities or exercises were included. Most of the 11 included studies assessed AT load when running or walking (N = 10), and only three tested exercises were usually performed during rehabilitation. The load on the tendon ranged from 2.7 to 3.95 BW when walking, from 4.15 to 7.71 BW when running, and from 0.41 to 7.3 BW according to the strengthening exercise performed. From the collected data, a progression of exercises progressively loading the Achilles tendon, as well as the possible connections with walking and running activities, could be defined. However, the trends highlighted in the relationship between tendon loading and walking or running speeds present some inconsistencies. Further research is still needed to clarify them, but also to complete the data set in healthy and injured people.

Between-Limb Symmetry in ACL and Tibiofemoral Contact Forces in Athletes After ACL Reconstruction and Clearance for Return to Sport.

Background: Current return-to-sport (RTS) criteria after anterior cruciate ligament (ACL) reconstruction (ACLR) include demonstrating symmetry in functional and strength tests. It remains unknown if at the time that athletes are cleared to RTS, they exhibit between-limb symmetry in ACL and tibiofemoral contact forces or if these forces are comparable with those in uninjured athletes. Purposes: To (1) examine ACL and tibiofemoral contact forces in athletes who underwent ACLR and were cleared to RTS and (2) compare the involved leg to the healthy contralateral leg and healthy controls during functional tasks. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 26 male athletes who underwent ACLR were tested at the time of RTS during tasks that included single-leg vertical, horizontal, and side jumps; cutting maneuvers; and high-intensity running. We used an electromyography-constrained musculoskeletal modeling workflow to estimate ACL and tibiofemoral contact forces and compared the results with those of 23 healthy male participants. Results: The ACLR group presented no differences in peak tibiofemoral contact forces in the involved limb compared with the control group. However, there were significant between-limb differences mainly due to higher contact forces in the uninvolved (healthy) limb of the ACLR group compared with the control group. In the ACLR group, ACL forces were significantly higher in the uninvolved limb compared with the involved limb during cutting and running. Lateral contact forces were lower in the involved compared with the uninvolved limb, with large effect sizes during cutting (d = 1.14; P < .001) and running (d = 1.10; P < .001). Conclusion: Current discharge criteria for clearance to RTS after ACLR did not ensure the restoration of symmetric loading in our cohort of male athletes. ACL force asymmetry was observed during cutting and running, in addition to knee loading asymmetries on several tasks tested.