Background Common lower limb postures have been found when noncontact anterior cruciate ligament (ACL) injuries occur during sidestep cutting tasks. These same postures have been linked to knee loadings known to stress the ACL. Hypothesis Whole body technique modification would reduce knee loading. Study Design Controlled laboratory study. Methods Experienced team sport athletes were recruited for whole body sidestep cutting technique modification. Before and after a 6-week technique modification training, participants performed sidestep cutting tasks while ground-reaction force and motion data were collected. A kinematic and inverse dynamics model was used to calculate 3-dimensional knee loading during sidestep cutting. Results At initial foot contact, the participants placed their stance foot closer to the body’s midline and held their torso more upright, in line with the aims of the technique modification training. This was accompanied by significantly lower peak valgus moments in the weight acceptance phase of stance. Both postural changes were correlated with the change in peak valgus moment. Conclusion Whole body sidestep cutting technique modification resulted in reduced knee loading. Clinical Relevance Implementation of whole body technique modification may produce effective ACL injury prevention programs in sports involving sidestep cutting.

Technique and knee loads in sidestep cutting 2 Abstract Purpose: To identify the effect of modifying sidestep cutting technique on knee loads and predict what impact such change would have on the risk of non-contact anterior cruciate ligament injury. Methods: A force platform and motion analysis system were used to record ground reaction forces and track the trajectories of markers on 15 healthy males performing sidestep cutting tasks using their normal technique and nine different imposed techniques. A kinematic and inverse dynamic model was used to calculate the three dimensional knee postures and moments. Results: The imposed techniques of foot wide, torso leaning in the opposite direction to the cut resulted in increased peak valgus moments experienced in weight acceptance. Higher peak internal rotation moments were found for the foot wide and torso rotation in the opposite direction to the cut techniques. The foot rotated in technique resulted in lower mean flexion/extension moments while the foot wide condition resulted in higher mean flexion/extension moments. The flexed knee, torso rotated in the opposite direction to the cut and torso leaning in the same direction as the cut techniques had significantly more knee flexion at heel strike. Conclusion: Sidestep cutting technique had a significant effect on loads experienced at the knee. The techniques which produced higher valgus and internal rotation moments at the knee, such as foot wide, torso leaning in the opposite direction to the cut and torso rotating in the opposite direction to the cut, may place an athlete at higher risk of injury as these knee loads have been shown to increase the strain on the anterior cruciate ligament. Training athletes to avoid such body positions may result in a reduced risk of non-contact anterior cruciate ligament injures.

The purpose of this study was to investigate the reliability and validity of predicting 1-repetition maximum (1RM) in trained individuals using a load-velocity relationship. Twenty strength-trained men (age: 24.3±2.9 years, height: 180.1±5.9 cm, body mass: 84.2±10.5 kg) were recruited and visited the laboratory on three occasions. The load-velocity relationship was developed using the mean concentric velocity of repetitions performed at loads between 20% and 90% 1RM. Predicted 1RM was calculated using 3 different methods discussed in existing research; minimal velocity threshold 1RM (1RMMVT), load at zero velocity 1RM (1RMLD0) and force-velocity 1RM methods (1RMFV). The reliability of 1RM predictions was examined using intraclass correlation coefficient (ICC) and coefficient of variation (CV). 1RMMVT demonstrated the highest reliability (ICC=0.92-0.96, CV=3.6-5.0%), followed by 1RMLD0 (ICC=0.78-0.82, CV=8.2-8.6%) and 1RMFV (ICC=-0.28-0.00, CV= N/A). Both 1RMMVT and 1RMLD0 were very strongly correlated with measured 1RM (r=0.91-0.95). The only method which was not significantly different to measured 1RM was the 1RMLD0 method. However, when analyzed on an individual basis (using Bland-Altman plots), all methods exhibited a high degree of variability. Overall, the results suggest that the 1RMMVT and 1RMLD0 predicted 1RM values could be used to monitor strength progress in trained individuals without the need for maximal testing. However, given the significant differences between 1RMMVT and measured 1RM, and the high variability associated with individual predictions performed using each method, they cannot be used interchangeably; therefore, it is recommended that predicted 1RM is not used to prescribe training loads as has been previously suggested.

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Purpose Determine if balance and technique training (BTT) implemented adjunct to normal Australian football (AF) training reduces external knee loading during sidestepping. Additionally, the authors determined if an athlete's knee joint kinematics and kinetics change over a season of AF. Methodology Eight amateur-level AF clubs (n=1,001 males) volunteered to participate in either 28 weeks of BTT or a 'sham' training (ST) adjunct to their normal preseason and regular training. A subset of 34 athletes (BTT, n=20; ST, n=14) were recruited for biomechanical testing in weeks 1-7 and 18-25 of the 28-week training intervention. During biomechanical testing, participants completed a series running, preplanned (PpSS) and unplanned sidestepping (UnSS) tasks. A linear mixed model (α=0.05) was used to determine if knee kinematics and peak moments during PpSS and UnSS were infl uenced by BTT and/or a season of AF.

Anterior cruciate ligament (ACL) injury rates have increased by ∼50% over the last 10 years. These figures suggest that ACL focused research has not been effective in reducing injury rates among community level athletes. Training protocols designed to reduce ACL injury rates have been both effective (n = 3) and ineffective (n = 7). Although a rationale for the use of exercise to reduce ACL injuries is established, the mechanisms by which they act are relatively unknown. This article provides an injury prevention framework specific to noncontact ACL injuries and the design of prophylactic training protocols. It is also apparent that feedback within this framework is needed to determine how biomechanically relevant risk factors like peak joint loading and muscular support are influenced following training. It is by identifying these links that more effective ACL injury prevention training programs can be developed, and, in turn, lead to reduced ACL injury rates in the future.

This study found that although knee muscle strength improved, dynamic medial joint load increased over the 2 yrs after APM surgery. These findings may aid in developing therapeutic interventions aimed to prevent or delay the onset of knee OA after APM.

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