1 3 Eur J Appl Physiol DOI 10.1007/s00421-017-3625-x LETTER TO THE EDITOR Could superimposed electromyostimulation be an effective training to improve aerobic and anaerobic capacity? Methodological considerations for its development Francisco J. Amaro-Gahete 1,2 · Alejandro de la O 1 · Lucas Jurado-Fasoli 1 · Jonatan R. Ruiz 2 · Ángel Gutiérrez 1 Received: 26 March 2017 / Accepted: 26 April 2017 © Springer-Verlag Berlin Heidelberg 2017 an EMS intervention (Mathes et al. 2017). However, we believe that several additional factors beyond the flow of local load exist that may help to better understand why one study did not find differences in aerobic and anaero- bic capacity in healthy men (Mathes et al. 2017) while the other study did (Miyamoto et al. 2016). Factors of both studies are extracted in Table 1. 1. High volume and low intensity training: In this study (Mathes et al. 2017) used an exercise intensity of 60% peak power output (PPO) to ensure a training within the high-volume low-intensity endurance training zone and control group reported a significant increase in PPO and V O 2 max similar to EMS group; however, another study (Helgerud et al. 2007) applied a 4 weeks training program which consisted running at 70% HR max for 45 min (four times per week) in healthy men similar to those who took part in the Mathes et al. (2017) study, and no differences were observed in V O 2 max . More specific data about the physiological adaptations of this specific training program are needed to fully understand the experimental problem. 2. High frequency vs. low frequency: The studies used different impulse frequency, 80 Hz (Mathes et al. 2017) vs. 4 Hz (Miyamoto et al. 2016); studies that present data related to the effects of high and low-fre- quency EMS training on aerobic parameters in healthy participants are scarce. Two studies showed improve- ments in aerobic capacity following low-frequency EMS training possibly mediated by adaptations in aerobic-oxidative metabolism and increased capillari- zation in healthy men (Veldman et al. 2016; Miyamoto et al. 2016). Nevertheless, high-frequency was usu- ally applied to develop strength parameters (Filipovic et al. 2011) and showed a positive influence in aerobic Dear Editor, We read with interest the study that discusses the findings observed in aerobic and anaerobic capacity in healthy, non- specifically trained sport students after 14 superimposed electromyostimulation (EMS) training sessions (60 min per session) over a 4-week period (Mathes et al. 2017). While this study found no differences in aerobic and anaero- bic capacity between groups, another interventional study (Miyamoto et al. 2016) reported an increase in aerobic and anaerobic capacity in healthy men after 16 EMS training sessions (30 min per session) over a 4-week period. Mathes et al. (2017) argued that no differences could be explained for (i) the lack of precision in the flow of local load in EMS group, (ii) the limited sample size and (iii) the high levels of muscle damage produced for EMS training with insuf- ficient recovery periods. We agree with authors that the lack of precision in the flow of local load in EMS group and the limited sample could explain the fact that there are no differences between groups on aerobic and anaerobic parameters and that spe- cial attention should be paid on that aspect when designing Communicated by Klaas R. Westerterp/Håkan Westerblad. This comment refers to the article available at doi:10.1007/ s00421-017-3572-6. * Francisco J. Amaro-Gahete amarof@ugr.es 1 Department of Medical Physiology, School of Medicine, University of Granada, Granada, Spain 2 PROmoting FITness and Health through physical activity research group (PROFITH), Department of Physical Education and Sports, Faculty of Sport Sciences, University of Granada, Granada, Spain