No agreement has been reached among strength and conditioning specialists as to what physical fitness exercises are most effective to stimulate activity of the core muscles. The authors’ purpose in writing this paper was to systematically review the literature on the electromyographic (EMG) activity of three core muscles (lumbar multifidus, transverse abdominis, quadratus lumborum) during physical fitness exercises in healthy adults. CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, PubMed, SPORTdiscus, and Web of Science databases were searched for relevant articles using a search strategy designed by the investigators. Seventeen studies enrolling 252 participants met the review’s inclusion/exclusion criteria. Physical fitness exercises were partitioned into five major types: traditional core, core stability, ball/device, free weight, and non-core free weight. Strength of evidence was assessed and summarized for comparisons among exercise types. The significant findings of the review with moderate levels of evidence suggest that lumbar multifidus EMG activity is greater during free weight exercises compared with ball/device exercises, and similar during core stability and ball/device exercises. Transverse abdominis EMG activity is similar during core stability and ball/device exercises. No studies were uncovered for quadratus lumborum EMG activity during physical fitness exercises.
The available evidence suggests that strength and conditioning specialists should spend more time implementing multi-joint free weight exercises, rather than core-specific exercises, so that they sufficiently train the core muscles in their athletes and clients.