Purpose Literature is conflicted on whether electromechanical delay durations decrease following resistance training programs. Therefore, the aim of this study is to examine the contributions and durations of the electrochemical (EMD E-M ) and mechanical (EMD M-F ) components to the overall electromechanical delay (EMD E-F ) during step isometric muscle actions following 4-weeks of structured, multi-joint, lower-body variable resistance training (VRT) program. Methods Twelve men performed 4-weeks of VRT leg press training utilizing combination of steel plates (80% total load) and elastic bands (20% total load). Training consisted of 3 sets of 10 repetitions at a 10 repetition maximum load, 3 day week −1 for 4-weeks. EMD E-M , EMD M-F , and EMD E-F was measured at Baseline, Week-2, and Week-4 during voluntary step isometric muscle actions (20, 40, 60, 80, and 100% of maximal voluntary isometric contraction) from the vastus lateralis using electromyographic, mechanomyographic, and force signals. Results The EMD E-M , EMD M-F , and EMD E-F exhibited decreases in duration following 4-weeks of VRT. In addition, EMD E-M contributed significantly less (42–47%) than EMD M-F (53–58%) to the total duration of EMD E-F across the 4-weeks of VRT. Conclusions These findings indicated that a structured, VRT program utilizing multi-joint exercise was sufficient to induce decreases in the electrochemical and mechanical processes associated with step isometric muscle contractions. In addition, the utilization of the electromyographic, mechanomyographic, and force signals were capable of quantifying electrochemical and mechanical component changes associated with voluntary muscle contraction. Thus, EMD E-M , EMD M-F , and EMD E-F can be useful in quantifying physiological changes in athletic, clinical, and applied research interventions.