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Beaulieu ML, Palmieri-Smith RM. Real-time feedback on knee abduction moment does not improve frontal-plane knee mechanics during jump landings. Scand J Med Sci Sports 2013; 24:692-9. [PMID: 23347094 DOI: 10.1111/sms.12051] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/13/2012] [Indexed: 12/31/2022]
Abstract
Excessive knee abduction loading is a contributing factor to anterior cruciate ligament (ACL) injury risk. The purpose of this study was to determine whether a double-leg landing training program with real-time visual feedback improves frontal-plane mechanics during double- and single-leg landings. Knee abduction angles and moments and vertical ground reaction forces (GRF) of 21 recreationally active women were quantified for double- and single-leg landings before and after the training program. This program consisted of two sessions of double-leg jump landings with real-time visual feedback on knee abduction moments for the experimental group and without real-time feedback for the control group. No significant differences were found between training groups. In comparison with pre-training data, peak knee abduction moments decreased 12% post-training for both double- and single-leg landings; whereas peak vertical GRF decreased 8% post-training for double-leg landings only, irrespective of training group. Real-time feedback on knee abduction moments, therefore, did not significantly improve frontal-plane knee mechanics during landings. The effect of the training program on knee abduction moments, however, transferred from the double-leg landings (simple task) to single-leg landings (more complex task). Consequently, ACL injury prevention efforts may not need to focus on complex tasks during which injury occurs.
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Affiliation(s)
- M L Beaulieu
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, USA
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Effects of task-specific augmented feedback on deficit modification during performance of the tuck-jump exercise. J Sport Rehabil 2012; 22:7-18. [PMID: 23238301 DOI: 10.1123/jsr.22.1.7] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
CONTEXT Anterior cruciate ligament (ACL) injuries are prevalent in female athletes. Specific factors have possible links to increasing a female athlete's chances of suffering an ACL injury. However, it is unclear if augmented feedback may be able to decrease possible risk factors. OBJECTIVE To compare the effects of task-specific feedback on a repeated tuck-jump maneuver. DESIGN Double-blind randomized controlled trial. SETTING Sports-medicine biodynamics center. PATIENTS 37 female subjects (14.7 ± 1.5 y, 160.9 ± 6.8 cm, 54.5 ± 7.2 kg). INTERVENTION All athletes received standard off-season training consisting of strength training, plyometrics, and conditioning. They were also videotaped during each session while running on a treadmill at a standardized speed (8 miles/h) and while performing a repeated tuck-jump maneuver for 10 s. The augmented feedback group (AF) received feedback on deficiencies present in a 10-s tuck jump, while the control group (CTRL) received feedback on 10-s treadmill running. MAIN OUTCOME MEASURES Outcome measurements of tuck-jump deficits were scored by a blinded rater to determine the effects of group (CTRL vs AF) and time (pre- vs posttesting) on changes in measured deficits. RESULTS A significant interaction of time by group was noted with the task-specific feedback training (P = .03). The AF group reduced deficits measured during the tuck-jump assessment by 23.6%, while the CTRL training reduced deficits by 10.6%. CONCLUSIONS The results of the current study indicate that task-specific feedback is effective for reducing biomechanical risk factors associated with ACL injury. The data also indicate that specific components of the tuck-jump assessment are potentially more modifiable than others.
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Padua DA, Distefano LJ. Sagittal Plane Knee Biomechanics and Vertical Ground Reaction Forces Are Modified Following ACL Injury Prevention Programs: A Systematic Review. Sports Health 2012; 1:165-73. [PMID: 23015868 PMCID: PMC3445071 DOI: 10.1177/1941738108330971] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Context: Injuries to the anterior cruciate ligament (ACL) occur because of excessive loading on the knee. ACL injury prevention programs can influence sagittal plane ACL loading factors and vertical ground reaction force (VGRF). Objective: To determine the influence of ACL injury prevention programs on sagittal plane knee biomechanics (anterior tibial shear force, knee flexion angle/moments) and VGRF. Data Sources: The PubMed database was searched for studies published between January 1988 and June 2008. Reference lists of selected articles were also reviewed. Study Selection: Studies were included that evaluated healthy participants for knee flexion angle, sagittal plane knee kinetics, or VGRF after performing a multisession training program. Two individuals reviewed all articles and determined which articles met the selection criteria. Approximately 4% of the articles fulfilled the selection criteria. Data Extraction: Data were extracted regarding each program’s duration, frequency, exercise type, population, supervision, and testing procedures. Means and variability measures were recorded to calculate effect sizes. One reviewer extracted all data and assessed study quality using PEDro (Physiotherapy Evidence Database). A second reviewer (blinded) verified all information. Results: There is moderate evidence to indicate that knee flexion angle, external knee flexion moment, and VGRF can be successfully modified by an ACL injury prevention program. Programs utilizing multiple exercises (ie, integrated training) appear to produce the most improvement, in comparison to that of single-exercise programs. Knee flexion angle was improved following integrated training (combined balance and strength exercises or combined plyometric and strength exercises). Similarly, external knee flexion moment was improved following integrated training consisting of balance, plyometric, and strength exercises. VGRF was improved when incorporating supervision with instruction and feedback on proper technique. Conclusion: ACL injury prevention programs that are aimed at modifying sagittal plane knee biomechanics and VGRF should use an integrated training approach that incorporates instruction and feedback on proper movement technique.
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Lauber B, Keller M. Improving motor performance: Selected aspects of augmented feedback in exercise and health. Eur J Sport Sci 2012; 14:36-43. [DOI: 10.1080/17461391.2012.725104] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Parsons JL, Alexander MJ. Modifying Spike Jump Landing Biomechanics in Female Adolescent Volleyball Athletes Using Video and Verbal Feedback. J Strength Cond Res 2012; 26:1076-84. [DOI: 10.1519/jsc.0b013e31822e5876] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Frost D, Andersen J, Lam T, Finlay T, Darby K, McGill S. The relationship between general measures of fitness, passive range of motion and whole-body movement quality. ERGONOMICS 2012; 56:637-649. [PMID: 22292560 DOI: 10.1080/00140139.2011.620177] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
UNLABELLED The goal of this study was to establish relationships between fitness (torso endurance, grip strength and pull-ups), hip range of motion (ROM) (extension, flexion, internal and external rotation) and movement quality in an occupational group with physical work demands. Fifty-three men from the emergency task force of a major city police force were investigated. The movement screen comprised standing and seated posture, gait, segmental spine motion and 14 tasks designed to challenge whole-body coordination. Relationships were established between each whole-body movement task, the measures of strength, endurance and ROM. In general, fitness and ROM were not strongly related to the movement quality of any task. This has implications for worker training, in that strategies developed to improve ROM or strength about a joint may not enhance movement quality. PRACTITIONER SUMMARY Worker-centered injury prevention can be described as fitting workers to tasks by improving fitness and modifying movement patterns; however, the current results show weak correlations between strength, endurance and ROM, and the way individuals move. Therefore, the development of occupation-specific injury prevention strategies may require both fitness and movement-oriented objectives.
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Affiliation(s)
- David Frost
- Spine Biomechanics Laboratories, University of Waterloo, Waterloo, Ontario, Canada
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Bien DP. Rationale and implementation of anterior cruciate ligament injury prevention warm-up programs in female athletes. J Strength Cond Res 2011; 25:271-85. [PMID: 21116195 DOI: 10.1519/jsc.0b013e3181fb4a5a] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The sex disparity in anterior cruciate ligament (ACL) injury risk and the subsequent adverse effects on knee joint health, psychosocial well-being, and financial costs incurred have produced a surge in research on risk factors and interventions designed to decrease this disparity and overall incidence. Biomechanical and neuromuscular differences have been identified throughout the trunk and lower extremity that may increase noncontact ACL injury risk in female athletes. Evidence demonstrates that many risk factors are modifiable with intervention programs and that athletic performance measures can be enhanced. No universally accepted ACL injury prevention program currently exists, and injury prevention programs are diverse. Anterior cruciate ligament injury prevention programs introduced in a warm-up format offer multiple benefits, primarily, improved compliance based on improved practicality of implementation. However, drawbacks of warm-up style formats also exist, most notably that a lack of equipment and resources may preclude measurable improvements in athletic performance that foster improved compliance among participants. The purpose of this review is to analyze the current literature researching possible biomechanical and neuromuscular risk factors in noncontact ACL injury in female athletes and the most effective means of implementing critical elements of a program to decrease ACL injury risk in female athletes while improving athletic performance. Hip and hamstring training, core stabilization, plyometrics, balance, agility, neuromuscular training with video and verbal feedback to modify technique, and stretching appear to be essential components of these programs. Further research is critical to determine ideal training program volume, intensity, duration, and frequency.
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Affiliation(s)
- Daniel P Bien
- Physical Therapy Department, University Orthopedics, Providence, Rhode Island, USA.
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Barber-Westin SD, Smith ST, Campbell T, Noyes FR. The drop-jump video screening test: retention of improvement in neuromuscular control in female volleyball players. J Strength Cond Res 2011; 24:3055-62. [PMID: 20940643 DOI: 10.1519/jsc.0b013e3181d83516] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A valgus lower limb alignment is commonly documented during noncontact anterior cruciate ligament injuries. We previously developed a videographic drop-jump test to measure overall lower limb alignment in the coronal plane as a screening tool to detect such an abnormal (valgus) position on landing. A neuromuscular retraining program developed for female athletes was shown to be effective in improving lower limb alignment on this test immediately after completion of training. What remained unknown was whether these improvements would be retained for longer periods of time. Therefore, this study was undertaken to determine if these improvements in overall lower limb alignment would be retained up to 1 year after the training. Sixteen competitive, experienced female high-school volleyball players underwent the video drop-jump test and then completed the neuromuscular retraining program. The program consisted of a dynamic warm-up, jump training, speed and agility drills, strength training, and static stretching and was performed 3 times a week for 6 weeks. The athletes repeated the drop-jump test immediately upon completion of training and then 3- and 12-months later. Significant improvements were found in the mean normalized knee separation distance between the pre and posttrained values for all test sessions (p < 0.01). Immediately after training, 11 athletes (69%) displayed significant improvements in the mean normalized knee separation distance that were retained 12 months later. Five athletes failed to improve. The video drop-jump test, although not a risk indicator for a knee ligament injury, provides a cost-effective general assessment of lower limb position and depicts athletes who have poor control on landing and acceleration into a vertical jump.
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Affiliation(s)
- Sue D Barber-Westin
- Cincinnati Sportsmedicine Research and Education Foundation, Cincinnati, Ohio, USA.
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ACL injury prevention, more effective with a different way of motor learning? Knee Surg Sports Traumatol Arthrosc 2011; 19:622-7. [PMID: 21079917 PMCID: PMC3062033 DOI: 10.1007/s00167-010-1313-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 10/14/2010] [Indexed: 10/25/2022]
Abstract
PURPOSE What happens to the transference of learning proper jump-landing technique in isolation when an individual is expected to perform at a competitive level yet tries to maintain proper jump-landing technique? This is the key question for researchers, physical therapists, athletic trainers and coaches involved in ACL injury prevention in athletes. The need for ACL injury prevention is clear, however, in spite of these ongoing initiatives and reported early successes, ACL injury rates and the associated gender disparity have not diminished. One problem could be the difficulties with the measurements of injury rates and the difficulties with the implementation of thorough large scale injury prevention programs. A second issue could be the transition from conscious awareness during training sessions on technique in the laboratory to unexpected and automatic movements during a training or game involves complicated motor control adaptations. The purpose of this paper is to highlight the issue of motor learning in relation to ACL injury prevention and to post suggestions for future research. CONCLUSION ACL injury prevention programs addressing explicit rules regarding desired landing positions by emphasizing proper alignment of the hip, knee, and ankle are reported in the literature. This may very well be a sensible way, but the use of explicit strategies may be less suitable for the acquisition of the control of complex motor skills (Maxwell et al. J Sports Sci 18:111-120, 2000). Sufficient literature on motor learning and it variations point in that direction.
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Abstract
STUDY DESIGN Single-subject with repeated measures. OBJECTIVES To determine if runners can use real-time visual feedback from an accelerometer to achieve immediate reductions in tibial acceleration and vertical-force loading rates. BACKGROUND Stress fractures are a common injury among runners. Previous studies suggest that runners with higher than normal tibial acceleration and vertical-force loading rates are at increased risk for tibial stress fractures. If these runners can be trained to reduce the loading on their lower extremities, it may reduce their risk of stress fractures. METHODS Five subjects participated in this study. All subjects ran on a treadmill, instrumented with force transducers, during a single 30-minute session that was divided into warm-up, feedback, no-feedback, and cool-down periods. During running, the subjects also wore an accelerometer taped to their distal right tibia. Peak positive acceleration of the tibia, vertical force impact peak, and average and instantaneous vertical-force loading rates were assessed at the end of the warm-up, feedback, and no-feedback periods. RESULTS Single-subject analysis revealed that 4 of the 5 subjects had significant reductions in their peak positive acceleration at the end of the no-feedback period compared to the warm-up. In addition, all of the subjects had significant decreases in impact peak and vertical ground reaction force loading rates at the end of the no-feedback period. CONCLUSION In a single session of training with real-time visual feedback, it appears that most runners can reduce the types of lower extremity loading associated with stress fractures. This may lead to training programs that reduce the risk of stress fractures for runners.
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Prevention of physical training-related injuries recommendations for the military and other active populations based on expedited systematic reviews. Am J Prev Med 2010; 38:S156-81. [PMID: 20117590 DOI: 10.1016/j.amepre.2009.10.023] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 07/15/2009] [Accepted: 10/08/2009] [Indexed: 12/26/2022]
Abstract
BACKGROUND The Military Training Task Force of the Defense Safety Oversight Council chartered a Joint Services Physical Training Injury Prevention Working Group to: (1) establish the evidence base for making recommendations to prevent injuries; (2) prioritize the recommendations for prevention programs and policies; and (3) substantiate the need for further research and evaluation on interventions and programs likely to reduce physical training-related injuries. EVIDENCE ACQUISITION A work group was formed to identify, evaluate, and assess the level of scientific evidence for various physical training-related injury prevention strategies through an expedited systematic review process. Of 40 physical training-related injury prevention strategies identified, education, leader support, and surveillance were determined to be essential elements of a successful injury prevention program and not independent interventions. As a result of the expedited systematic reviews, one more essential element (research) was added for a total of four. Six strategies were not reviewed. The remaining 31 interventions were categorized into three levels representing the strength of recommendation: (1) recommended; (2) not recommended; and (3) insufficient evidence to recommend or not recommend. EVIDENCE SYNTHESIS Education, leadership support, injury surveillance, and research were determined to be critical components of any successful injury prevention program. Six interventions (i.e., prevent overtraining, agility-like training, mouthguards, semirigid ankle braces, nutrient replacement, and synthetic socks) had strong enough evidence to become working group recommendations for implementation in the military services. Two interventions (i.e., back braces and pre-exercise administration of anti-inflammatory medication) were not recommended due to evidence of ineffectiveness or harm, 23 lacked sufficient scientific evidence to support recommendations for all military services at this time, and six were not evaluated. CONCLUSIONS Six interventions should be implemented in all four military services immediately to reduce physical training-related injuries. Two strategies should be discouraged by all leaders at all levels. Of particular note, 23 popular physical training-related injury prevention strategies need further scientific investigation, review, and group consensus before they can be recommended to the military services or similar civilian populations. The expedited systematic process of evaluating interventions enabled the working group to build consensus around those injury prevention strategies that had enough scientific evidence to support a recommendation.
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Schmitz RJ, Kim H, Shultz SJ. Effect of axial load on anterior tibial translation when transitioning from non-weight bearing to weight bearing. Clin Biomech (Bristol, Avon) 2010; 25:77-82. [PMID: 19837495 PMCID: PMC2795012 DOI: 10.1016/j.clinbiomech.2009.09.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 09/10/2009] [Accepted: 09/11/2009] [Indexed: 02/07/2023]
Abstract
BACKGROUND While the application of compressive joint loads and thigh muscle activity are associated with anterior tibial translation in vitro, less is known during early load acceptance in vivo. We investigated the effects of increasing axial loads on anterior tibial translation and thigh muscle activity in healthy knees during transition from non-weight bearing to early weight bearing. METHODS Participants (11 males, 11 females) underwent 20%, 40%, and 60% body weight acceptance trials at 20 degrees knee flexion while electromagnetic sensors measured anterior tibial translation (mm), and surface electromyography recorded quadriceps and hamstring muscle onset times (ms) and amplitudes (% maximal voluntary isometric contraction). Repeated measures ANOVA compared values across loads. Pearson correlations examined relationships between anterior tibial translation and muscle onset times and amplitudes within each load. FINDINGS As load increased, anterior tibial translation (Mean (standard deviation)) (20%=4.7 (1.7) mm<40%=7.1 (1.9) mm<60%=8.8 (2.1) mm), and quadriceps (20%=23.6 (14.9)% maximal voluntary isometric contraction <40%=32.7 (11.8)% maximal voluntary isometric contraction <60%=41.1 (13.5)% maximal voluntary isometric contraction) and hamstring (20%=15.5 (15.7)% maximal voluntary isometric contraction <40%=23.0 (16.4)% maximal voluntary isometric contraction <60%=27.6 (19.1)% maximal voluntary isometric contraction) activation increased, while quadriceps (20%=96.7 (28.4) ms>60% 80.2 (21.8) ms) and hamstring (20%=141.5 (65.0) ms and 40%=126.3 (68.8)>60% 107.6 (28.4) ms) onset times decreased (P0.05). There were no relationships between anterior tibial translation and muscle activation amplitudes (R=0.033-0.294) or onset times (R=-0.031-0.374) (P>0.09). INTERPRETATION Greater axial loads near full knee extension during early weight acceptance result in greater anterior tibial translation, regardless of faster and stronger activation amplitudes. These findings support injury prevention programs aimed to reduce impact forces as they may in turn reduce anterior tibial translation and corresponding ligamentous strain during dynamic activity.
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Alentorn-Geli E, Myer GD, Silvers HJ, Samitier G, Romero D, Lázaro-Haro C, Cugat R. Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 2: a review of prevention programs aimed to modify risk factors and to reduce injury rates. Knee Surg Sports Traumatol Arthrosc 2009; 17:859-79. [PMID: 19506834 DOI: 10.1007/s00167-009-0823-z] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Accepted: 05/08/2009] [Indexed: 12/14/2022]
Abstract
Soccer is the most commonly played sport in the world, with an estimated 265 million active soccer players participating in the game as on 2006. Inherent to this sport is the higher risk of injury to the anterior cruciate ligament (ACL) relative to other sports. ACL injury causes a significant loss of time from competition in soccer, which has served as the strong impetus to conduct research that focuses to determine the risk factors for injury, and more importantly, to identify and teach techniques to reduce this injury in the sport. This research emphasis has afforded a rapid influx of literature aimed to report the effects of neuromuscular training on the risk factors and the incidence of non-contact ACL injury in high-risk soccer populations. The purpose of the current review is to sequence the most recent literature relating the effects of prevention programs that were developed to alter risk factors associated with non-contact ACL injuries and to reduce the rate of non-contact ACL injuries in soccer players. To date there is no standardized intervention program established for soccer to prevent non-contact ACL injuries. Multi-component programs show better results than single-component preventive programs to reduce the risk and incidence of non-contact ACL injuries in soccer players. Lower extremity plyometrics, dynamic balance and strength, stretching, body awareness and decision-making, and targeted core and trunk control appear to be successful training components to reduce non-contact ACL injury risk factors (decrease landing forces, decrease varus/valgus moments, and increase effective muscle activation) and prevent non-contact ACL injuries in soccer players, especially in female athletes. Pre-season injury prevention combined with an in-season maintenance program may be advocated to prevent injury. Compliance may in fact be the limiting factor to the overall success of ACL injury interventions targeted to soccer players regardless of gender. Thus, interventional research must also consider techniques to improve compliance especially at the elite levels which will likely influence trickle down effects to sub-elite levels. Future research is also needed for male soccer athletes to help determine the most effective intervention to reduce the non-contact ACL injury risk factors and to prevent non-contact ACL injuries.
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Affiliation(s)
- Eduard Alentorn-Geli
- Artroscopia GC, Dr Ramón Cugat's Office, Hospital Quirón, Plaza Alfonso Comín 5-7, 08023 Barcelona, Spain.
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Herman DC, Oñate JA, Weinhold PS, Guskiewicz KM, Garrett WE, Yu B, Padua DA. The effects of feedback with and without strength training on lower extremity biomechanics. Am J Sports Med 2009; 37:1301-8. [PMID: 19299530 DOI: 10.1177/0363546509332253] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Feedback instruction is a proven modality for the alteration of motion patterns. There are no existing data on the contribution of strength training, when combined with feedback instruction, to the altering of lower extremity biomechanics. HYPOTHESIS Lower extremity muscle strength training provides an increased capacity to alter knee and hip biomechanics during a stop-jump task in response to a feedback protocol. STUDY DESIGN Controlled laboratory study. METHODS Knee and hip 3-dimensional kinematic and kinetic data were collected for 58 female recreational athletes while performing 3 stop-jump tasks after completing a 9-week strength training program (ST-FB; n = 29) or a 9-week period of no strength training (FB; n = 29). Data were then collected for both groups after completing a jump-landing feedback instruction protocol. Knee and hip joint angles, as well as resultant forces and moments, were calculated. RESULTS Across all participants, there were decreased peak vertical ground-reaction forces (P < .001) and increased knee flexion (P = .050), hip flexion (P < .001), and hip abduction (P = .032) angles, subsequent to the feedback protocol. Hip abduction angle (P < .001) increased in the ST-FB group but not the FB group, and peak knee anterior shear force (P = .015) decreased in the ST-FB group but increased in the FB group (P = .009). CONCLUSION The results indicate that strength training, when used in conjunction with video-assisted feedback, may provide an increased capacity for the alteration of knee and hip biomechanics. CLINICAL RELEVANCE Programs that include both strength training and movement education through feedback may be necessary to increase the effectiveness of anterior cruciate ligament prevention programs. Strength training may provide an increased capacity for athletes to respond to other intervention modalities used in anterior cruciate ligament injury prevention programs.
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Affiliation(s)
- Daniel C Herman
- Center for Human Movement Science, Division of Physical Therapy, University of North Carolina, Chapel Hill, North Carolina, USA.
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Effects of a plyometric program on vertical landing force and jumping performance in college women. Phys Ther Sport 2008; 9:185-92. [DOI: 10.1016/j.ptsp.2008.08.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Revised: 06/16/2008] [Accepted: 08/06/2008] [Indexed: 11/21/2022]
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Walsh MS, Waters J, Kersting UG. Gender Bias on the Effects of Instruction on Kinematic and Kinetic Jump Parameters of High-level Athletes. Res Sports Med 2007; 15:283-95. [DOI: 10.1080/15438620701693306] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Mark S. Walsh
- a Physical Education, Health and Sports Studies Department , Miami University , Oxford, Ohio, USA
| | - Jeff Waters
- b Jeff Waters Consulting , Fairfield, Ohio, USA
| | - Uwe G. Kersting
- c Department of Sport and Exercise Science , The University of Auckland , Auckland, New Zealand
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Abstract
Lower extremity injuries in figure skating have long been linked to skating boot stiffness, and recent increases in jump practice time may be influencing the frequency and seriousness of these injuries. It is hypothesized that stiff boots compromise skaters' abilities to attenuate jump landing forces. Decreasing boot stiffness by adding an articulation at the ankle may reduce the rate and magnitude of landing forces. Prototype articulated figure skating boots were tested in this study to determine their effectiveness in enabling skaters to land with lower peak impact forces. Nine competitive figure skaters, who trained in standard boots and subsequently in articulated boots, performed off-ice jump simulations and on-ice axels, double toe loops, and double axels. Analysis of the off-ice simulations showed decreases in peak heel force and loading rate with use of the articulated boot, although the exact kinematic mechanisms responsible for these decreases are still unclear. Analysis of the on-ice jumps revealed few kinematic differences between boot types, implying that the skaters did not use the articulation. Greater adaptation and training time is likely needed for the results seen off-ice to transfer to difficult on-ice jumps.
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Affiliation(s)
- Dustin A Bruening
- Human Performance Laboratory, University of Delaware, Newark, DE 19716, USA
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Chmielewski TL, Myer GD, Kauffman D, Tillman SM. Plyometric exercise in the rehabilitation of athletes: physiological responses and clinical application. J Orthop Sports Phys Ther 2006; 36:308-19. [PMID: 16715831 DOI: 10.2519/jospt.2006.2013] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Plyometric exercise was initially utilized to enhance sport performance and is more recently being used in the rehabilitation of injured athletes to help in the preparation for a return to sport participation. The identifying feature of plyometric exercise is a lengthening of the muscle-tendon unit followed directly by shortening (stretch-shortening cycle). Numerous plyometric exercises with varied difficulty and demand on the musculoskeletal system can be implemented in rehabilitation. Plyometric exercises are initiated at a lower intensity and progressed to more difficult, higher intensity levels. The progression to higher-intensity plyometric exercise is thought to resolve postinjury neuromuscular impairments and to prepare the musculoskeletal system for rapid movements and high forces that may be similar to the demands imposed during sport participation, thus assisting the athlete with a return to full function. While there is a large body of scientific literature that supports the use of plyometric exercise to enhance athletic performance, evidence is sparse regarding the effectiveness of plyometric exercise in promoting a quick and safe return to sport after injury. This review will describe the mechanisms involved in plyometric exercise, discuss the considerations for implementing plyometric exercise into rehabilitation protocols, examine the evidence supporting the use of plyometric exercises, and make recommendations for future research.
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Affiliation(s)
- Terese L Chmielewski
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610, USA.
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Myer GD, Ford KR, McLean SG, Hewett TE. The effects of plyometric versus dynamic stabilization and balance training on lower extremity biomechanics. Am J Sports Med 2006; 34:445-55. [PMID: 16282579 DOI: 10.1177/0363546505281241] [Citation(s) in RCA: 241] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Neuromuscular training that includes both plyometric and dynamic stabilization/balance exercises alters movement biomechanics and reduces ACL injury risk in female athletes. The biomechanical effects of plyometric and balance training utilized separately are unknown. HYPOTHESIS A protocol that includes balance training without plyometric training will decrease coronal plane hip, knee, and ankle motions during landing, and plyometric training will not affect coronal plane measures. The corollary hypothesis was that plyometric and balance training effects on knee flexion are dependent on the movement task tested. STUDY DESIGN Controlled laboratory study. METHODS Eighteen high school female athletes participated in 18 training sessions during a 7-week period. The plyometric group (n = 8) performed maximum-effort jumping and cutting exercises, and the balance group (n = 10) used dynamic stabilization/ balance exercises during training. Lower extremity kinematics were measured during the drop vertical jump and the medial drop landing before and after training using 3D motion analysis techniques. RESULTS During the drop vertical jump, both plyometric and balance training reduced initial contact (P = .002), maximum hip adduction angle (P = .015), and maximum ankle eversion angle (P = .020). During the medial drop landing, both groups decreased initial contact (P = .002) and maximum knee abduction angle (P = .038). Plyometric training increased initial contact knee flexion (P = .047) and maximum knee flexion (P = .031) during the drop vertical jump, whereas the balance training increased maximum knee flexion (P = .005) during the medial drop landing. CONCLUSION Both plyometric and balance training can reduce lower extremity valgus measures. Plyometric training affects sagittal plane kinematics primarily during a drop vertical jump, whereas balance training affects sagittal plane kinematics during single-legged drop landing. CLINICAL RELEVANCE Both plyometric and dynamic stabilization/balance exercises should be included in injury-prevention protocols.
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Affiliation(s)
- Gregory D Myer
- Cincinnati Children's Hospital, 3333 Burnet Avenue, MLC 10001, Cincinnati, OH 45229, USA.
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71
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Lephart SM, Abt JP, Ferris CM, Sell TC, Nagai T, Myers JB, Irrgang JJ. Neuromuscular and biomechanical characteristic changes in high school athletes: a plyometric versus basic resistance program. Br J Sports Med 2006; 39:932-8. [PMID: 16306502 PMCID: PMC1725089 DOI: 10.1136/bjsm.2005.019083] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND In order to improve neuromuscular and biomechanical characteristic deficits in female athletes, numerous injury prevention programs have been developed and have successfully reduced the number of knee ligament injuries. However, few have investigated the neuromuscular and biomechanical changes following these training programs. It is also largely unknown what type of program is better for improving the landing mechanics of female athletes. OBJECTIVES To investigate the effects of an 8 week plyometric and basic resistance training program on neuromuscular and biomechanical characteristics in female athletes. METHODS Twenty seven high school female athletes participated either in a plyometric or a basic resistance training program. Knee and hip strength, landing mechanics, and muscle activity were recorded before and after the intervention programs. In the jump-landing task, subjects jumped as high as they could and landed on both feet. Electromyography (EMG) peak activation time and integrated EMG of thigh and hip muscles were recorded prior to (preactive) and subsequent to (reactive) foot contact. RESULTS Both groups improved knee extensor isokinetic strength and increased initial and peak knee and hip flexion, and time to peak knee flexion during the task. The peak preactive EMG of the gluteus medius and integrated EMG for the gluteus medius during the preactive and reactive time periods were significantly greater for both groups. CONCLUSIONS Basic training alone induced favourable neuromuscular and biomechanical changes in high school female athletes. The plyometric program may further be utilised to improve muscular activation patterns.
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Affiliation(s)
- S M Lephart
- Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA, USA.
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Oñate JA, Guskiewicz KM, Marshall SW, Giuliani C, Yu B, Garrett WE. Instruction of jump-landing technique using videotape feedback: altering lower extremity motion patterns. Am J Sports Med 2005; 33:831-42. [PMID: 15827359 DOI: 10.1177/0363546504271499] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Anterior cruciate ligament injury prevention programs have used videotapes of jump-landing technique as a key instructional component to improve landing performance. HYPOTHESIS All videotape feedback model groups will increase knee flexion angles at initial contact and overall knee flexion motion and decrease peak vertical ground reaction forces and peak proximal anterior tibial shear forces to a greater extent than will a nonfeedback group. The secondary hypothesis is that the videotape feedback using the combination of the expert and self models will create the greatest change in each variable. STUDY DESIGN Controlled laboratory study. METHODS Knee kinematics and kinetics of college-aged recreational athletes randomly placed in 3 different videotape feedback model groups (expert only, self only, combination of expert and self) and a nonfeedback group were collected while participants performed a basketball jump-landing task on 3 testing occasions. RESULTS All feedback groups significantly increased knee angular displacement flexion angles [F(6,70) = 8.03, P = .001] and decreased peak vertical ground reaction forces [F(6,78) = 2.68, P = .021] during performance and retention tests. The self and combination groups significantly increased knee angular displacement flexion angles more than the control group did; the expert model group did not change significantly more than the control group did. All feedback groups and the nonfeedback group significantly reduced peak vertical forces across performance and retention tests. There were no statistically significant changes in knee flexion angle at initial ground contact (P = .111) and peak proximal anterior tibial shear forces (P = .509) for both testing sessions for each group. CONCLUSION The use of self or combination videotape feedback is most useful for increasing knee angular displacement flexion angles and reducing peak vertical forces during landing. CLINICAL RELEVANCE The use of self or combination modeling is more effective than is expert-only modeling for the implementation of instructional programs aimed at reducing the risk of jump-landing anterior cruciate ligament injuries.
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Affiliation(s)
- James A Oñate
- University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
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Noyes FR, Barber-Westin SD, Fleckenstein C, Walsh C, West J. The drop-jump screening test: difference in lower limb control by gender and effect of neuromuscular training in female athletes. Am J Sports Med 2005; 33:197-207. [PMID: 15701605 DOI: 10.1177/0363546504266484] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND A valgus lower limb alignment has been noted during noncontact anterior cruciate ligament injuries. A video drop-jump test can indicate an athlete's ability to control lower limb axial alignment in the coronal plane. HYPOTHESES Female athletes have decreased knee separation distances on landing and acceleration; male athletes have a neutrally aligned lower limb position. A neuromuscular training program will significantly increase knee separation distance in female athletes. STUDY DESIGN Cohort study; Level of evidence, 2. METHODS The authors tested 325 female and 130 male athletes aged 11 to 19 years. The distance between the hips, knees, and ankles was measured during a drop-jump test. The separation distance between the knees and ankles was normalized by the hip separation distance. A neuromuscular training program (Sportsmetrics) was completed by 62 female athletes, and their jump-landing characteristics were reexamined. RESULTS A marked decrease in knee separation distance was found on takeoff in 80% of female athletes and in 72% of male athletes. There was no difference between male and female athletes in the normalized knee and ankle separation distance during the landing and takeoff phases. The knee separation distance on landing was 23 +/- 9 cm in the female athletes and 22 +/- 8 cm in the male athletes. The normalized knee separation distance was 51% +/- 19% in the female athletes and 51% +/- 15% in the male athletes. After training, statistically significant increases were found in the female athletes in the knee separation distance on landing (29 +/- 8 cm, P < .0001) and in the normalized knee separation distance (68% +/- 18%, P < .0001). The trained female athletes had significantly greater knee separation distance and normalized knee separation distance than did the males (P < .0001). CONCLUSIONS The majority of untrained female and male athletes demonstrated a valgus alignment appearance on the video test. After neuromuscular training, female athletes had improved knee separation distances and a more neutral lower limb alignment on landing and takeoff.
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Affiliation(s)
- Frank R Noyes
- Cincinnati Sportsmedicine Research and Education Foundation, Cincinnati, Ohio, USA
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Abstract
The absorption of impacts resulting from contact with a landing surface during gait, running and drop landings has received considerable attention in the literature. This research has important clinical relevance as failure to appropriately plan and control impact absorption may lead to injuries to the musculo-skeletal system. This review attempts to summarize evidence gathered by studies on the motor control aspects of impact absorption during landing movements. Although this review focuses primarily on the control of landings from self-initiated falls or 'drop landings', an understanding of the motor control mechanisms underlying impact absorption is essential to understand common anticipatory and reflex mechanisms involved in a broader variety of movements such as running and jumping. The review is structured in three parts: the first two parts examine the preparatory muscle activity occurring during the fall (Part I) and after touch down (Part II). Part III explores the proposed sensorimotor mechanisms underlying the control of landing. The review concludes with as yet unresolved questions and directions for future research.
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Affiliation(s)
- Marco Santello
- Department of Kinesiology and the Harrington Department of Bioengineering, PEBE 107B, Orange Street, Arizona State University, Tempe, AZ 85287-0404, USA.
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Prapavessis H, McNair PJ, Anderson K, Hohepa M. Decreasing landing forces in children: the effect of instructions. J Orthop Sports Phys Ther 2003; 33:204-7. [PMID: 12723677 DOI: 10.2519/jospt.2003.33.4.204] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
STUDY DESIGN Randomized controlled experimental design. OBJECTIVES To examine the effects of verbal instructions related to control of joint kinematics and auditory feedback on lowering the vertical peak ground reaction forces associated with landing from a jump in children. BACKGROUND The majority of children's injuries are associated with activities that involve jumping and landing. Instructions related to joint motion may assist children in decreasing landing forces and thus reduce the chances of sustaining an injury. METHODS AND MEASURES Sixty-one school children whose mean (+/- SD) age was 9 (+/- 0.89) years participated. The children were randomly assigned (by school) to either experimental (received instruction on lower limb position and auditory cues) or control (received no instruction) groups. Participants were required to step off a box 300 mm in height and land on a force plate. The testing procedure involved 5 sessions. The first 4 sessions were performed over 3 days in the same week, while session 5 was performed approximately 3 months later to assess retention of the skill. The main outcome measure was the peak vertical ground reaction force recorded at foot strike. RESULTS After instructions, subjects in the experimental group produced lower peak ground reaction forces (P<0.05) during landing compared to their control counterparts (ie, sessions 2-4). There was no significant difference (P<0.05) between groups at session 5 (3 months postinstruction). CONCLUSIONS Children are capable of assimilating precise instruction to minimize forces on the lower limbs during landing from a jump. Providing further opportunity (ie, more than 1 session) to perform the skill does not alter the magnitude of the effect observed after the initial session of instruction. However, the improvements in landing performance were temporary.
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Affiliation(s)
- Harry Prapavessis
- Department of Sport and Exercise Science, University of Auckland, Auckland, New Zealand
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