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.

Success in tennis requires a mix of player talent, good coaching, appropriate equipment, and an understanding of those aspects of sport science pertinent to the game. This paper outlines the role that biomechanics plays in player development from sport science and sport medicine perspectives. Biomechanics is a key area in player development because all strokes have a fundamental mechanical structure and sports injuries primarily have a mechanical cause.

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Eighty-two high performance young male fast bowlers (mean age 16.8 years) were tested immediately prior to the season for selected kinanthropometric and physiological data. Subjects were also filmed both laterally (200 Hz) and from above (100 Hz) while bowling so that their front foot impacted a force platform during the delivery stride. The players then completed a log book over the ensuing season that detailed their training and playing programmes. All cricket related injuries over this season were assessed by a sports physician who used computerized tomography to assist in the diagnosis of spinal injuries.At the completion of this season the players were grouped according to their injury status (Group 1-bony injury to a vertebra; Group 2-soft tissue injury to the back that caused the player to miss at least one game, and Group 3 -no injuries). A one-way analysis of variance was used to identify if any variables were significantly (P < 0.05) different between the three groups, and a Scheffe post hoc comparison was used to determine which groups were significantly different.Eleven per cent of the players sustained a stress fracture to a vertebra(e) (L4 to Si), while 27 per cent sustained a soft tissue injury to the back. Bowlers with a low longitudinal foot arch were more likely to develop a stress fracture than those with a high arch. Shoulder depression and horizontal flexion strength for the preferred limb and quadriceps power in the non-preferred limb were also significantly related to back injuries. Bowlers who rotated the trunk to re-align the shoulders by more than 400 to a more side-on position between back foot impact and front foot impact in the delivery stride were more likely to sustain back injuries. No significant relationship was determined between peak vertical (5.4 BW) or horizontal (-2.