LETTER TO THE EDITOR Authors’ Reply to Ribeiro et al.: ‘‘A Review of the Acute Effects and Long-Term Adaptations of Single- and Multi-Joint Exercises During Resistance Training’’ Paulo Gentil 1 • James Steele 2 • James Fisher 2 Ó Springer International Publishing Switzerland 2016 Dear Editor, We thank Ribeiro et al. [1] for taking the time to read our article [2] and propose discussion around some of the topics raised. Essentially, the authors appear to question the conclusion that individuals performing resistance training (RT) may not need to include single-joint (SJ) exercises in their program to obtain optimal results in terms of muscle hypertrophy. Ribeiro et al. [1] begin by reporting that most studies investigated only the elbow flexor muscles and suggest that inferences in this regard cannot be generalized to other muscles from the current literature. In support, the corre- spondents state that ‘‘MJ (multi joint) shoulder press pri- marily targets the anterior deltoid’’, citing Botton et al. [5]. However, this argument is flawed. The first flaw (present in other parts of the letter) is to suggest that a difference in electromyographic (EMG) activity would necessarily result in significant differences in muscle gains, which is a common and basic mistake [6]. Moreover, the authors fail to fairly represent the article cited. Botton et al. [5] reported that performing a free-weight lateral raise, cable crossover lateral raise, and reverse pec deck (all SJ exer- cises) demonstrated similar medial deltoid activation to a seated row (MJ) exercise; therefore, one cannot suggest that SJ abduction would be needed to maximize growth in the medial deltoid head by using this reference. Moreover, the suggestion by Ribeiro et al. [1] may be challenged by other studies. For example, the results of Paoli et al. [7] show that EMG amplitudes for medial deltoids are not inferior to those for anterior deltoids during the shoulder press. The suggestion that a shoulder press targets primarily the anterior deltoid is not because of its MJ nature, but might rather be explained by electrode position, normalization procedures, and exercise technique (for example, if one performs a shoulder press with the elbows pointing forward it will involve more elbow flex- ion, whilst if the elbows are externally rotated, then shoulder abduction would occur). In addition, the suggestion that medial deltoids are less activated during MJ exercises in comparison with anterior deltoids proves to be inconsistent when analyzing other exercises. For example, Shick et al. [8] reported that medial deltoid activation during a free-weight bench press exercise was higher compared with anterior deltoid activation, which is also supported by the results of Dunnick et al. [9]. We acknowledge that these EMG studies alone cannot be used to infer chronic adaptations with the present lack of chronic training studies investigating deltoid hypertrophy or strength gains in shoulder flexion, abduction, and extension. However, we feel at present there is insufficient evidence to suggest inclusion of SJ exercises for this joint as being necessary. Ribeiro et al.’s [1] suggestion that one may need different SJ exercises to promote specific hypertrophy in different portions of the same muscles (such as the medial and posterior heads of the deltoids) appears to be based on the belief that muscle hypertrophy occurs in an almost millimetric manner, an anecdotal argument usually proposed in lay circles that does not have any physiological & Paulo Gentil paulogentil@hotmail.com 1 Faculdade de Educac¸a˜o Fı ´sica e Danc¸a (FEFD), Universidade Federal de Goia´s (UFG), Campus Samambaia, Avenida Esperanc¸a s/n, Goiaˆnia, Goia´s CEP 74.690-900, Brazil 2 School of Sport, Health, and Social Sciences, Southampton Solent University, Southampton, UK 123 Sports Med DOI 10.1007/s40279-016-0665-z