Abstract
Within the conceptual framework of muscular imbalances (MI) it is commonly assumed that altered muscle performance characteristics (i.e. strength deficits) are associated with a higher risk of overuse or traumatic injury or re-injury. However, scientific literature reveals several difficulties which question the general adequacy of this framework.
According to recent lines of evidence it seems that 1) quantification of balance of muscle performance is problematic and hence classification of an imbalanced muscle function is also difficult 2) a clear system which is able to differentiate between normal (balanced) or abnormal(imbalanced) muscle performance cannot be established universally 3) it is still not evident if and to what extent a relatively higher increase of function of prime movers predisposes an athlete to a higher risk of injury 4) assessment of muscle function in relation to the onset of musculoskeletal disorders has to be based on several aspects of muscle function; single-factor-related analysis (e.g. uniplanar strength ratio) reflects an insufficient approach.
As a consequence, this paper recommends a preliminary alternative approach in an attempt to assess muscle function in relation to both performance and injury prevention and muscular recovery after injury. Within a multifactorial approach, detailed qualitative and quantitative observations should reveal if arthro-neuromuscular function is in a state of adaptation, de-adaptation or compensation and if joint function and/or whole body mechanics are limited. In addition, emphasis has to be put on the importance of the transfer of the results into structured treatment strategies.