Muscle imbalance

The concept of muscle imbalance (and balance) is not new. This is evidenced through over 60 years of texts involving muscle testing and function (Kendall et al. 2005) and has evolved over the most recent of those years through work from the likes of Janda (1983), Sahrmann (1987), Richardson (1992), Jull et al. (1999) and others. Clearly, alterations in muscle balance cannot be considered in isolation, but must be considered as part of movement control, where the differentiation of the factors leading to movement dysfunction is essential and part of the holistic assessment and management of individuals with musculoskeletal pain. This chapter concentrates on the adaptation of muscle in relation to posture and movement patterns, and the relationship to musculoskeletal pain syndromes. The following knowledge and understanding of the reader will be assumed: • the micro- and macro-anatomical structure and physiology of muscle and associated tissue; • micro- and macrostructure related to function; • macro-anatomy or gross anatomy of muscles and muscle groups, along with their relationships to each other and other tissue structures, such as bones, joints, connective tissue, viscera, neural and vascular tissue; in other words, what lies deep, superficial, superior, inferior, medial and lateral to the structure being considered.