Different visual stimuli affect body reorientation strategies during sidestepping

Abstract

Sidestepping in response to unplanned stimuli is a high-risk maneuver for anterior cruciate ligament (ACL) injuries. Yet, differences in body reorientation strategies between high- and low-level soccer players prior to sidestepping in response to quasi-game-realistic vs non-game-realistic stimuli, remain unknown. Fifteen high-level (semi-professional) and 15 low-level (amateur) soccer players responded to a quasi-game-realistic one-defender scenario (1DS) and two-defender scenario (2DS), and non-game-realistic arrow-planned condition (AP) and arrow-unplanned condition (AUNP). The AP, 1DS, 2DS to AUNP represented increasing time constraints to sidestep. Selected biomechanics from the penultimate step to foot-off were assessed using a mixed-model (stimuli × skill) ANOVA (P < 0.05). Step length decreased in the defender scenarios compared with the arrow conditions. Support foot placement increased laterally, away from mid-pelvis, with increasing temporal constraints. Greater trunk lateral flexion in the 1DS, 2DS, and AUNP has been associated with ACL injury onsets. Higher level players pushed off closer to their pelvic midline at initial foot contact in the 2DS especially. Higher level perception of game-realistic visual information could have contributed to this safer neuromuscular strategy that, when understood better, could potentially be trained in lower level players to reduce ACL injury risk associated with dangerous sidestepping postures.

Role of the Penultimate Foot Contact During Change of Direction: Implications on Performance and Risk of Injury

“…68) states that directional changes must be planned and initiated in the step before the turn to facilitate effective COD performance. This is substantiated by previous studies that have reported athletes make anticipatory postural adjustments (APA) in the step prior to (penultimate foot contact (PFC)) the COD (final foot contact (FFC)), demonstrating kinematic changes in foot placement, trunk lean and rotation, and head rotation (37,51,60,69,93,95). Furthermore, braking characteristics such as greater braking forces and external knee flexor moments (KFM) have been reported in the step prior (PFC) to CODs ≥ 60˚ (20,25,(42)(43)(44)(45), highlighting the importance of the PFC during extreme directional changes.…”

The Effect of Angle and Velocity on Change of Direction Biomechanics: An Angle-Velocity Trade-Off

“…1 ). Unfortunately, however, the results of Jones et al [ 62 ] indicate that unanticipated situations do not allow postural adjustments prior to the FFC to evoke greater braking force characteristics during the PFC; however, it should be noted that the unanticipated COD task involved responding to a light stimuli, which is more challenging than using a sports-specific stimulus [ 63 , 64 ], and it also lacks specificity to the sporting situations where athletes typically scan and process kinematic and postural cues prior to changing direction [ 65 ]. Further research is warranted investigating the role of the PFC during unanticipated tasks utilising sports-specific stimuli.…”

“…Changing direction is described as a multi-step action [ 61 ], with research indicating the step(s) prior to the COD are pivotal in deceleration and initiating effective CODs [ 34 – 38 , 53 , 58 – 60 , 64 , 66 , 128 – 133 ]. Specifically, researchers have shown that the greater braking force characteristics demonstrated in the PFC during COD can alleviate knee joint loading [ 36 – 38 ] and also facilitate faster turning performance [ 58 – 60 ]; however, only two studies have examined the effect of approach velocity on PFC biomechanics.…”

Change of Direction Assessment Following Anterior Cruciate Ligament Reconstruction: A Review of Current Practice and Considerations to Enhance Practical Application

“…Planned CoDs that have been used previously in the assessment of CoD following ACLr (i.e., carioca, shuttle, co contraction, T test, cutting) without temporal constraints may afford sufficient time for the adoption of a 'safer' and more optimal movement execution. For example, the support foot placement strategy (i.e., more medial to the pelvic midline) prior to initial contact of the push-off foot to initiate the direction change, thus lowering the mechanical stress on the knee [47]. Performing an unplanned task can be in response to either generic (react against 2 dimension planned and unplanned light-based directional arrows) and quasi-realistic (react against 1 or 2 defenders' scenarios in a 3-dimension video projection) external stimuli.…”