There was recently a discussion about hamstring injuries on social media during which somebody asked if "extension" can be a contributory factor. This was our answer:
If by "extension" you mean a motor strategy suggestive of lower cross syndrome or anterior pelvic tilt, it might be relevant to this discussion. Different ways of saying the same thing often distract us from the principles that unite commercial movement systems. While hamstring strains are multi-factorial, an extension pattern/anterior pelvic tilt/lower cross syndrome could alter motor control at the pelvis during early stance in sprinting in a way that puts hamstring tissue at risk for injury - which is why it's so hard to differentiate mechanical from neurological archetypes.
Athletes who default to a motor pattern suggestive of anterior pelvic tilt in competition often have limitations in hip extension, which some coaches here would agree might influence sprint performance. Similarly, an anterior pelvic tilt pattern limits hip internal rotation (1), a variable we probably want to prioritize in rotational and field sport athletes before something like FAI manifests as pain. These neurologically-driven biomechanical explanations are empirical, not theoretical.
Many professionals recognize the value of movement-based interventions before athletes reach a painful threshold. We can't label an athlete with something abstract like “extension” without an objective assessment. Hence the value of a systematic method of movement analysis. While movement analysis, which includes orthopedic special tests, can't "predict" injury (nothing can), it allows us to mitigate risk based on known biomechanical and neurological phenomena to program in a way that, along with other information, reduces the cost of training and maximizes the benefit. The relevance of non-painful mobility and motor control anomalies is contingent upon the notion that pain can distract us from more problematic areas.
We know that pain alters motor control and compromises the validity of testing in the vicinity of a painful joint. Presumably the non-painful movement patterns existed before the injury - they are non-painful and thus not in a state of threat - and are worth addressing because they alter motor control and mechanics elsewhere in the body (e.g. the athlete with knee pain who lacks dorsiflexion and rotation at the hip). Knowledge of behavioral states, like an "extension" pattern or lower cross syndrome, help explain on a macro level what a systemic evaluation uncovers on a micro or more local level.
- Ross JR, Nepple JJ, Philippon MJ, Kelly BT, Larson CM, Bedi A. Effect of Changes in Pelvic Tilt on Range of Motion to Impingement and Radiographic Parameters of Acetabular Morphologic Characteristics. Am J Sports Med 2014 42: 2402.