Neuromuscular Fatigue During Heavy Resistance Drop Set Training to Failure

ABSTRACT: Jakobsen, MD, Sundstrup, E, and Andersen, LL. Neuromuscular fatigue during heavy resistance drop set training to failure. J Strength Cond Res XX(X): 000-000, 2026-Training to momentary muscular fatigue is an important variable in resistance exercise planning. Current research largely focuses on muscle activity in single resistance training repetitions, leaving a gap in understanding neuromuscular fatigue over complete sessions. The purpose of this study was to determine the neuromuscular responses during a leg press drop set (DS) training bout to momentary muscular fatigue. Nineteen novice subjects (6 women, 13 men, aged 28-67) completed a DS routine involving 3 sets to muscle failure at 10-12 repetition maximum loads. Electromyographic activity from 6 leg muscles: vastus medialis (VM), vastus lateralis, rectus femoris, biceps femoris, semitendinosus, and gluteus maximus was recorded to evaluate neuromuscular fatigue indices: Normalized EMG (nEMG), Wavelet Index Ratio (WIRW51), and Median Power Frequency (MPF). Knee joint angles were measured using inclinometers. Across repetitions, nEMG increased in all muscles except VM and ST and did not differ across sets. MPF decreased with repetition in all muscles except BF and decreased across sets in all muscles except GM. WIRW51 increased within repetitions and across sets for all muscles except GM. Range of motion and contraction time declined as repetitions accumulated and were unchanged across sets. Accordingly, drop set resistance training induces significant neuromuscular fatigue across multiple muscle groups, evidenced by increased nEMG, decreased MPF, and altered WIRW51. These findings inform more targeted and effective resistance exercise programming for maximizing momentary muscular fatigue.