Strength training induces neural adaptations that can be studied according to the modification in the activation levels of the agonist, synergist and antagonist muscles. The aim of this study is to review and evaluate the most important studies that investigated the role of antagonist muscles’s coactivation in neural adaptations of strength training. Muscular coactivation or co-contraction is defined as the activity of the agonist muscles, simultaneously with a low level activity of the antagonist muscles of the same joint. Among others, coactivation plays an important role in the stability of a joint and also in the production of accurate, smooth and coordinated movements. Generally, strength training is believed to control the antagonist activation by: a) reducing it, in combination to an augmentation or not of the agonist muscle activation and b) by keeping it stable and increasing the agonist activation, resulting in a reduction of the antagonist/agonist activation ratio. According to the present review, the role of antagonist coactivation in the neuromuscular adaptations of strength training is not considerable compared to the observed strength enhancement. Further research concerning coactivation and more general neuromuscular adaptations is necessary.