Context : Tasks that activate the lateral trunk muscles are clinically relevant in athletic and rehabilitation programs . However, no electromyography studies have compared tasks aimed at lateral trunk muscle activation . Objective . To compare the activation magnitudes of the internal and external obliques between 4 tasks targeting recruitment of the lateral trunk muscles, including the proposal of a novel assessment . Design : Comparative laboratory study . Setting : University - based biomechanics laboratory . Participants. Sixty - three participants ( 35 females, age = 23 . 6 [ 2 . 0] y, height = 1 . 72 [0 . 10] m, mass = 70 .7 [ 14 . 41 kg, body mass index = 23. 6 [ 2 . 86] kg/m -). Intervention(s ): Surface electromyography data were recorded bilaterally from the internal and external obliques while the participants performed 2 maximum voluntary contraction tasks followed by 4 isometric tasks. The isometric tasks included feet-elevated side-supported. trunk-elevated side-unsupported. lateral plank, and side-lying hip abduction. Main Outcome Measures : Maximum voluntary contraction - normalized and integrated muscle activities were calculated for targeted and nontargeted muscles in each task. A side-by-task analysis o f variance with Bonferroni correction was conducted. Results : The trunk - elevated side - unsupported task strongly activated the internal ( 1 99 % maximum voluntary contraction) and external ( 103%) oblique muscles. The feet-elevated side-supported task strongly activated the internal obliques (205%) but not the external obliques (55%). The lateral plank task successfully activated the internal (107%) and external (72%) obliques, but not at the highest levels of the tested tasks. The side-lying hip abduction task was the least effective at activating either the internal (48 %) or external ( 20 %) obliques . Conclusions . We recommend the novel trunk - elevated side - unsupported task for assessing lateral trunk muscle performance. For independent exercise, we recommend the lateral plank task, unless arm or shoulder pathologies are present, whereby the feet-elevated side-supported task may be favorable. [ABSTRACT FROM AUTHOR]