The effects of age and skill level on knee musculature co-contraction during functional activities: A systematic review

Objectives: To systematically review the current literature that relates the effects of age and skill level to motor control patterns of knee musculature co-contraction during functional movements. Methods: A search of electronic databases was performed with the search terms specifying co-contraction (cocontract*, co-contract*, coactive* or co-activ*). The search was focused on the effects age and/or skill level and were limited by the keywords of age or skill level (skill*) or experience (experi*). Results: The search yielded a total of six peer-reviewed manuscripts that met the search criteria and were included in the review. Conclusions: The relationship between adequate dynamic joint stability and efficient movement patterns are complex. Co-contraction related to age and skill development varies among studies due to technical and practical considerations. Adequate antagonistic co-contraction of hamstring musculature seems to be a component of all functional movements, possibly maintain dynamic knee stability and protect against excessive joint loads. Future investigations that further delineate the appropriate lower extremity agonist and antagonist relationships during dynamic tasks may help elucidate injury risk mechanisms in specific populations.