Injury, Training, Biomechanical, and Physiological Profiles of Professional Breakdancers.

Background: Breakdancing or breaking will enter the Olympics in 2024, however, there is a paucity of literature exploring the epidemiology, demands, and performance. Purpose: The purpose of this study was to describe injury and training profiles, along with the results of a short performance test battery, in a group of elite breakers. Study Design: Cross-sectional study (retrospective). Methods: Fourteen breakdancers (breakers) (4 Bgirls, 10 Bboys) participated in an interview regarding their injury and training history, endurance test (cycle VO2max testing), counter movement jump, squat jump, drop jump, isometric hip abduction, adduction, shoulder external and internal rotation strength testing on a fixed-frame dynamometer. Breakers were divided into elite (n=10) and developing (n=4) based on their qualification for a world finals competition; Wilcoxen rank sums were used to compare the two groups, or in the case of strength testing between those with and without an injury history. Results: The breakers had a median 11.0 [10.0 - 14.0] years breaking experience and trained 24.4 [20.5 - 30.0] hours per week. The knee was the most commonly injured body part and most frequently injured joint, with the thigh being the most common site for muscle injuries. There were no differences in endurance testing or jump height testing results between elite and developing breakers. There was no difference in shoulder external or internal rotation strength between athletes with a history of shoulder injury and those without. Similarly, there was no difference in hip abduction or adduction strength in those with a history of hip injury and those without. Conclusion: The results of this study should be viewed with caution due to the small sample size. However, this study is the first to publish functional and physiological descriptives on breakers. The authors hope these results support clinicians treating breakers as well as encourages future research related to breaking. Level of Evidence: 2b.

Description, Prediction, and Causation in Sport and Exercise Medicine Research: Resolving the Confusion to Improve Research Quality and Patient Outcomes.

SYNOPSIS: Researchers often assign a label (such as a risk factor or predictor) to a characteristic that is statistically associated with an outcome (such as future injury). Labeling signifies that the characteristic has an established clinical value. More often than not, these labels are assigned prematurely and haphazardly. The rampant practice conflates research goals, the ultimate clinical value of the findings, and many risk factors/predictors that may not warrant the label. To address these issues and improve injury prevention research, we (1) outline the problem; (2) clarify the key differences between the research goals of description, causation, and prediction/prognosis (along with labeling conventions); (3) differentiate the clinical implications for each label; and (4) frame an appropriate scientific process to follow before applying a label. J Orthop Sports Phys Ther 2023;53(7):1-7. Epub: 26 April 2023. doi:10.2519/jospt.2023.11773.

Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention.

The Academy of Orthopaedic Physical Therapy and the American Academy of Sports Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This guideline focuses on the exercise-based prevention of knee injuries and provides an update on the 2018 guideline, J Orthop Sports Phys Ther. 2018;48(9):A1-A42. doi:10.2519/jospt.2018.0303 J Orthop Sports Phys Ther. 2023;53(1):CPG1-CPG34. doi:10.2519/jospt.2023.0301.

ACL injury prevention: Where have we come from and where are we going?

Anterior cruciate ligament (ACL) injuries are one of the most common and severe knee injuries across sports. As such, ACL injury prevention has been a focus of research and sports medicine practice for the past three-plus decades. Examining the current research and identifying both clinical strategies and research gaps, the aim of this review is to empower clinicians and researchers with knowledge of where the ACL injury prevention literature is currently and where it is going in the future. This paper examines the mechanism of ACL injury prevention, screening, implementation, compliance, adherence, coronavirus, and areas of future research. Clinical significance: The time lag between research and practical implementation in general healthcare settings can be as long as 17 years; however, athletes playing sports today are unable to wait that long. With effective programs already established, implementation and adherence to these programs is essential. Strategies such as coaching education, increasing awareness of free programs, identifying barriers, and overcoming implementation obstacles through creative collaboration are just a few ways that could help improve both ACL injury prevention implementation and adherence.

Characterization of Rookie Season Injury and Illness and Career Longevity Among National Basketball Association Players.

Importance: There is limited research investigating injury and illness among professional basketball players during their rookie season. By improving the understanding of injury incidence and risk specific to rookie players, sports medicine clinicians may be able to further individualize injury mitigation programs that address the unique needs of rookie players. Objective: To compare incidence and rate ratio (RR) of injury and illness among professional National Basketball Association (NBA) players in their rookie season with veteran players and to explore the association of sustaining an injury rookie season with career longevity. Design, Setting, and Participants: This retrospective cohort study used an online data repository and extracted publicly available data about NBA players between the 2007 and 2008 season to the 2018 and 2019 season. Available data for initial injury and all subsequent injuries were extracted during this time frame. Exposures: Injury and illness based on injury status during the rookie season of professional NBA players. Main Outcomes and Measures: Injury and illness incidence and RR. Association of injury during the rookie season with career longevity was assessed via Poisson regressions. Results: Of the 12 basketball seasons analyzed, 904 NBA players were included (mean [SD] age, 24.6 [3.9] years; body mass index, 24.8 [1.8]). The injury and illness incidence for rookie players was 14.28 per 1000 athlete game exposures (AGEs). Among all body regions, ankle injuries had the greatest injury incidence among players injured during their rookie season (3.17 [95% CI, 3.15-3.19] per 1000 AGEs). Rookie athletes demonstrated higher RR compared with veterans across multiple regions of the body (ankle: 1.32; 95% CI, 1.12 to 1.52; foot/toe: 1.29; 95% CI, 0.97 to 1.61; shoulder/arm/elbow: 1.43; 95% CI, 1.10 to 1.77; head/neck: 1.21; 95% CI, 0.61 to 1.81; concussions: 2.39; 95% CI, 1.89 to 2.90; illness: 1.14; 95% CI, 0.87 to 1.40), and demonstrated a higher rate of initial injuries compared with veteran players (1.41; 95% CI, 1.29 to 1.53). Players who sustained an injury rookie season demonstrated an unadjusted decrease in total seasons played (-0.4 [95% CI, -0.5 to -0.3] log years; P < .001), but this decrease was not observed within adjusted analysis (0.1 [95% CI, -0.1 to 0.2] log years; P = .36). Conclusions and Relevance: In this study, rookie athletes demonstrated the highest injury incidence at the ankle and increased RR across multiple regions. These findings may reflect differences in preseason conditioning or load variables impacting rookie athletes and warrant further investigation. Future research is needed to determine the association of cumulative injury burden vs a singular injury event on career longevity.

A Secondary Injury Prevention Program May Decrease Contralateral Anterior Cruciate Ligament Injuries in Female Athletes: 2-Year Injury Rates in the ACL-SPORTS Randomized Controlled Trial.

OBJECTIVE: To determine whether the addition of perturbation training to a secondary injury prevention program reduces the rate of second anterior cruciate ligament (ACL) injury compared to the prevention program alone. DESIGN: Single-blinded randomized controlled trial. METHODS: Thirty-nine female athletes who intended to return to cutting/pivoting sports were enrolled 3 to 9 months after primary anterior cruciate ligament reconstruction (ACLR). Athletes were randomized to receive a training program of either progressive strengthening, agility, plyometrics, and prevention (SAPP) (n = 20) or SAPP plus perturbation training (n = 19); each had 10 sessions over 5 weeks. Occurrence and side of second ACL injury were recorded for 2 years after primary ACLR. RESULTS: There were 9 second ACL injuries in the 2 years after ACLR. There was no statistically significant difference in rate or side of second ACL injury between the SAPP-plus-perturbation training and SAPP groups. CONCLUSION: Adding perturbation training to a secondary ACL injury prevention program did not affect the rate of second ACL injury in female athletes. J Orthop Sports Phys Ther 2020;50(9):523-530. Epub 1 Aug 2020. doi:10.2519/jospt.2020.9407.

TUCK JUMP SCORE IS NOT RELATED TO HOPPING PERFORMANCE OR PATIENT-REPORTED OUTCOME MEASURES IN FEMALE SOCCER PLAYERS.

BACKGROUND: The tuck jump assessment was developed to identify players at risk for anterior cruciate ligament (ACL) injuries or gauge a player's progress through rehabilitation after ACL reconstruction. A tuck jump score of ≥ 6 out of 10 has been labeled poor and thought to identify players with high risk landing patterns. PURPOSE: The purpose of this exploratory study was to examine if there was a relationship between tuck jump score, particularly tuck jump scores ≥ 6, hopping performance, and patient-reported outcome measures in female soccer players with ACL reconstruction (ACLR) and knee-healthy controls. STUDY DESIGN: Secondary analysis of prospective cohort study. METHODS: Female soccer players (117 after ACLR, 117 knee-healthy) performed the single hop for distance, tuck jump assessment, and drop vertical jump (DVJ). All players were categorized based on as having a total tuck jump score ≥ 6 or < 6. Analyzing all players together, Spearman's rank correlations assessed if there were relationships between total tuck jump score or tuck jump scores ≥ 6 and single-legged hop limb symmetry or DVJ measures. Players with an ACLR also filled out the International Knee Documentation Committee 2000 Subjective Knee Form and the Knee injury Osteoarthritis Outcome Score. Spearman's rank correlations assessed if there were relationships between total tuck jump score or tuck jump scores ≥ 6 and patient-reported outcome measures. RESULTS: The mean tuck jump scores was 4.8 ± 1.8 (tuck jump score ≥ 6, 6.7 ± 0.9, tuck jump score < 6, 3.7 ± 1.1) with 87 (37%) athletes having tuck jump score ≥ 6. There were no significant relationships between tuck jump score or tuck jump score ≥ 6 and hopping performance or patient-reported outcome measures. CONCLUSION: The results of this current study indicate that tuck jump scores, including tuck jump scores ≥ 6, may not be related to functional or patient-reported outcome measures. Further work is needed to examine the clinical utility of the tuck jump assessment. LEVEL OF EVIDENCE: 2.

Jump performance in male and female football players.

PURPOSE: To examine differences between men and women football players in clinically feasible jumping measures. METHODS: Female football players (N = 46, ages 16-25) were matched based on age, training frequency, and playing position with 46 male players. All players performed the tuck jump and drop vertical jump (DVJ). DVJ was assessed quantitatively for valgus knee motion and probability of a high peak knee abduction moment (pKAM), as well as sagittal plane hip, knee, and ankle angles, and qualitatively with visual assessment of the player's knees upon landing; graded as good, reduced, or poor control. RESULT: Women had higher total tuck jump scores (5 ± 2) (more technique flaws), than men (3 ± 2, P < 0.01). The quantitative analysis of the DVJ found that men had greater asymmetries between limbs, but women landed bilaterally in more knee valgus (interaction P = 0.04, main effect of sex P = 0.02). There was no difference in pKAM (interaction n.s.). Women also landed in less hip flexion (P = 0.01) and ankle dorsiflexion (P = 0.01) than men. The qualitative DVJ analysis found that more women (48%) had poor knee control compared to men (11%, P < 0.01). CONCLUSIONS: The results indicate that women perform worse on the tuck jump assessment than men. The results support previous findings that women land in more knee valgus than men, but also found that men may have larger asymmetries in knee valgus. These results from clinically feasible measures provide some suggestions for clinicians to consider during ACL reconstruction rehabilitation to enhance performance.

Jumping performance based on duration of rehabilitation in female football players after anterior cruciate ligament reconstruction.

PURPOSE: To determine if female football players who had longer durations of rehabilitation, measured in months, after anterior cruciate ligament reconstruction would have lower tuck jump scores (fewer technique flaws) and smaller asymmetries during drop vertical jump landing. METHODS: One-hundred-and-seventeen female football players, aged 16-25 years, after primary unilateral ACL reconstruction (median 16 months, range 6-39) were included. Athletes reported the duration of rehabilitation they performed after anterior cruciate ligament reconstruction. Athletes also performed the tuck jump and drop vertical jump tests. Outcome variables were: tuck jump score, frontal plane knee motion and probability of peak knee abduction moment during drop vertical jump landing. RESULTS: There was no difference in tuck jump score based on duration of rehabilitation (n.s.). No interaction (n.s.), difference between limbs (n.s.), or duration of rehabilitation (n.s.) was found for peak knee abduction moment during drop vertical jump landing. No interaction (n.s.) or difference between limbs (n.s.) was found for frontal plane knee motion, but there was a difference based on duration of rehabilitation (P = 0.01). Athletes with > 9 months of rehabilitation had more frontal plane knee motion (medial knee displacement) than athletes with < 6 months (P = 0.01) or 6-9 months (P = 0.03). CONCLUSION: As there was no difference in tuck jump score or peak knee abduction moment based on duration of rehabilitation, the results of this study press upon clinicians the importance of using objective measures to progress rehabilitation and clear athletes for return to sport, rather than time alone. LEVEL OF EVIDENCE: II.

Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention.

The Academy of Orthopaedic Physical Therapy and the American Academy of Sports Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This particular guideline focuses on the exercise-based prevention of knee injuries. J Orthop Sports Phys Ther. 2018;48(9):A1-A42. doi:10.2519/jospt.2018.0303.

Changes in biomechanical knee injury risk factors across two collegiate soccer seasons using the 11+ prevention program.

The 11+ injury prevention program effectively reduces injuries in high school-aged female soccer player, but the mechanism of the 11+ is unknown, particularly whether it impacts biomechanical risk factors associated with knee injuries. The purpose of this study was to report the changes in hip and knee biomechanics with use of the 11+ over two soccer seasons. Two collegiate women's soccer teams performed the 11+ for two soccer seasons. A control team was followed for one season. Athletes performed motion analysis of a drop vertical jump during preseason and postseason. Both groups had meaningful increases in peak knee abduction angle over the first season, and there were no meaningful changes in peak knee abduction moment over either season. The control group had bilateral decreases in knee flexion angle. The program did not seem to systematically impact biomechanical risk factors associated with knee injuries, with increases in peak knee abduction angle and no bilateral changes in frontal or transverse hip motion. The 11+ may have mitigated clinically meaningful decreases in knee flexion; however, as ACL injuries do not occur purely in the sagittal plane, it is unclear the impact of these changes. The results of this study indicate that the 11+ may require some modifications to impact landing biomechanics and potentially risky movement patterns, particularly when used in collegiate women over multiple seasons.

TWO YEAR ACL REINJURY RATE OF 2.5%: OUTCOMES REPORT OF THE MEN IN A SECONDARY ACL INJURY PREVENTION PROGRAM (ACL-SPORTS).

BACKGROUND: The Anterior Cruciate Ligament-Specialized Post-Operative Return to Sports (ACL-SPORTS) randomized control trial (RCT) examined an evidence-based secondary ACL injury prevention training program, involving progressive strengthening, agility training, and plyometrics. The RCT examined the benefit of the training program with and without a neuromuscular training technique called perturbation training. HYPOTHESIS/PURPOSE: The purpose of this study was to report the return to sport and second ACL injury incidence outcomes of the men in the ACL-SPORTS trial. STUDY DESIGN: Secondary analysis of a RCT. METHODS: Forty cutting and pivoting sport male athletes participated in the ACL-SPORTS trial, return to sport testing, and in follow-up sessions at one and two years after ACL reconstruction. Variables of interest at one and two years were return to sport, return to preinjury level of sport, and second ACL injuries. Mean time to passing return to sport criteria, the number of athletes returning to sport and preinjury level of sport and the incidence proportion of second ACL injuries were calculated. RESULTS: Athletes passed return to sport criteria 232 ± 99 days after ACLR. One year after ACL reconstruction 95% had returned to sport, 78% at their preinjury level. Two years after ACL reconstruction all athletes had returned to sport, 95% at their preinjury level and only one athlete had a second ACL injury. CONCLUSIONS: The results of this study indicate that men in the ACL-SPORTS trial had much higher return to sport rates and much lower second ACL injury rates than those reported in the literature. LEVEL OF EVIDENCE: 1b.

Functional and Patient-Reported Outcomes Improve Over the Course of Rehabilitation: A Secondary Analysis of the ACL-SPORTS Trial.

BACKGROUND: The Anterior Cruciate Ligament-Specialized Post-Operative Return to Sports (ACL-SPORTS) randomized controlled trial was designed to address deficits in functional and patient-reported outcomes. The trial examined the effects of a secondary ACL prevention program that included progressive strengthening, agility training, plyometrics (SAP), and other components of current primary prevention protocols, with perturbation training (SAP + PERT group) and without PERT (SAP group). A secondary purpose of this study was to examine whether study outcomes differed between men and women. HYPOTHESES: (1) Athletes in both the SAP and SAP + PERT groups will have improved knee function and patient-reported outcome measures from pre- to posttraining, (2) the SAP + PERT group would have higher outcome scores than the SAP group, and (3) outcomes will differ by sex. STUDY DESIGN: Randomized controlled trial (NCT01773317). LEVEL OF EVIDENCE: Level 2. METHODS: A total of 79 athletes (39 women) were randomized into the SAP and SAP + PERT groups. All athletes had undergone primary ACL reconstruction and achieved 80% quadriceps strength limb symmetry (QI), full range of motion, had minimal effusion, and had no pain. Additionally, all had begun running again. Prior to and after the training program, athletes' QI, hopping, and patient-reported outcomes were assessed. Repeated-measures analyses of variance were used to determine whether there were differences between groups. Subsequently, the SAP and SAP + PERT groups were collapsed to analyze differences between sexes. RESULTS: There were significant increases for all variables, with the exception of QI. There were no differences between the SAP and SAP + PERT groups. Both men and women made significant improvements in all knee function and patient-reported outcome measures except QI. Men made significant improvements in QI, whereas women did not. CONCLUSION: The common elements of the training program that all athletes received (10 sessions of progressive strengthening, agility training, plyometrics, and secondary prevention) may be a beneficial addition to the return-to-sport phase of ACL reconstruction rehabilitation. The results suggest that women may require further quadriceps strengthening to maintain and improve QI, an important focus given the relationship between QI and risk for reinjury. CLINICAL RELEVANCE: During the return-to-sport phase of ACL reconstruction rehabilitation, clinicians tend to shift their focus away from strengthening toward more advanced sports-related tasks. These results indicate that women in particular need continued focus on quadriceps strengthening.

Gait mechanics and tibiofemoral loading in men of the ACL-SPORTS randomized control trial.

The risk for post-traumatic osteoarthritis is elevated after anterior cruciate ligament reconstruction (ACLR), and may be especially high among individuals with aberrant walking mechanics, such as medial tibiofemoral joint underloading 6 months postoperatively. Rehabilitation training programs have been proposed as one strategy to address aberrant gait mechanics. We developed the anterior cruciate ligament specialized post-operative return-to-sports (ACL-SPORTS) randomized control trial to test the effect of 10 post-operative training sessions consisting of strength, agility, plyometric, and secondary prevention exercises (SAPP) or SAPP plus perturbation (SAPP + PERT) training on gait mechanics after ACLR. A total of 40 male athletes (age 23 ± 7 years) after primary ACLR were randomized to SAPP or SAPP + PERT training and tested at three distinct, post-operative time points: 1) after impairment resolution (Pre-training); 2) following 10 training sessions (Post-training); and 3) 2 years after ACLR. Knee kinematic and kinetic variables as well as muscle and joint contact forces were calculated via inverse dynamics and a validated electromyography-informed musculoskeletal model. There were no significant improvements from Pre-training to Post-training in either intervention group. Smaller peak knee flexion angles, extension moments, extensor muscle forces, medial compartment contact forces, and tibiofemoral contact forces were present across group and time, however the magnitude of interlimb differences were generally smaller and likely not meaningful 2 years postoperatively. Neither SAPP nor SAPP + PERT training appears effective at altering gait mechanics in men in the short-term; however, meaningful gait asymmetries mostly resolved between post-training and 2 years after ACLR regardless of intervention group. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2364-2372, 2018.

Report of the Clinical and Functional Primary Outcomes in Men of the ACL-SPORTS Trial: Similar Outcomes in Men Receiving Secondary Prevention With and Without Perturbation Training 1 and 2 Years After ACL Reconstruction.

BACKGROUND: Athletes often are cleared to return to activities 6 months after anterior cruciate ligament (ACL) reconstruction; however, knee function measures continue to improve up to 2 years after surgery. Interventions beyond standard care may facilitate successful return to preinjury activities and improve functional outcomes. Perturbation training has been used in nonoperative ACL injury and preoperative ACL reconstruction rehabilitation, but has not been examined in postoperative ACL reconstruction rehabilitation, specifically return to sport rehabilitation. QUESTIONS/PURPOSES: The purpose of this study was to determine whether there were differences at 1 and 2 years after ACL reconstruction between the male SAP (strengthening, agility, and secondary prevention) and SAP+PERT (SAP protocol with the addition of perturbation training) groups with respect to (1) quadriceps strength and single-legged hop limb symmetry; (2) patient-reported knee outcome scores; (3) the proportion who achieve self-reported normal knee function; and (4) the time from surgery to passing return to sport criteria. METHODS: Forty men who had completed ACL reconstruction rehabilitation and met enrollment criteria (3-9 months after ACL reconstruction, > 80% quadriceps strength limb symmetry, no pain, full ROM, minimal effusion) were randomized into the SAP or SAP+PERT groups of the Anterior Cruciate Ligament-Specialised Post-Operative Return to Sports trial (ACL-SPORTS), a single-blind randomized clinical study of secondary prevention and return to sport. Quadriceps strength, single-legged hopping, the International Knee Documentation Committee (IKDC) 2000 subjective knee form, Knee Injury and Osteoarthritis Outcome Score (KOOS)-sports and recreation, and KOOS-quality-of-life subscales were collected 1 and 2 years after surgery by investigators blind to group. Athletes were categorized as having normal or abnormal knee function at each time point based on IKDC score, and the time until athletes passed strict return-to-sport criteria was also recorded. T-tests, chi square tests, and analyses of variance were used to identify differences between the treatment groups over time. RESULTS: There were no differences between groups for quadriceps symmetry (1 year: SAP = 101% ± 14%, SAP+PERT = 101% ± 14%; 2 years: SAP = 103% ± 11%, SAP+PERT = 98% ± 14%; mean differences between groups at 1 year: 0.4 [-9.0 to 9.8], 2 years = 4.5 [-4.3 to 13.1]; mean difference between 1 and 2 years: SAP = -1.0 [-8.6 to 6.6], SAP+PERT = 3.0 [-4.3 to 10.3], p = 0.45) or single-legged hop test limb symmetry. There were no clinically meaningful differences for any patient-reported outcome measures. There was no difference in the proportion of athletes in each group who achieved normal knee function at 1 year (SAP 14 of 19, SAP+PERT 18 of 20, odds ratio 0.31 [0.5-19.0]; p = 0.18); however, the SAP+PERT group had fewer athletes with normal knee function at 2 years (SAP 17 of 17, SAP+PERT 14 of 19, p = 0.03). There were no differences between groups in the time to pass return to sport criteria (SAP = 325 ± 199 days, SAP+PERT = 233 ± 77 days; mean difference 92 [-9 to 192], p = 0.09). CONCLUSIONS: This randomized trial found few differences between an ACL rehabilitation program consisting of strengthening, agility, and secondary prevention and one consisting of those elements as well as perturbation training. In the absence of clinically meaningful differences between groups in knee function and self-reported outcomes measures, the results indicate that perturbation training may not contribute additional benefit to the strengthening, agility, and secondary prevention base of the ACL-SPORTS training program. LEVEL OF EVIDENCE: Level II, therapeutic study.

Controversies in knee rehabilitation: anterior cruciate ligament injury.

Controversy in management of athletes exists after anterior cruciate ligament (ACL) injury and reconstruction. Consensus criteria for evaluating successful outcomes following ACL injury include no reinjury or recurrent giving way, no joint effusion, quadriceps strength symmetry, restored activity level and function, and returning to preinjury sports. Using these criteria, the success rates of current management strategies after ACL injury are reviewed and recommendations are provided for the counseling of athletes after ACL injury.