Muscle Activation Does Not Increase After a Fatigue Plateau Is Reached During 8 Sets of Resistance Exercise in Trained Individuals

Abstract

The premise of eliciting the greatest acute fatigue is accepted and used for designing programs that include excessive, potentially dangerous volumes of high-intensity resistance exercise. There is no evidence examining acute fatigue and neuromuscular responses throughout multiple sets of moderate-to-high intensity resistance exercise. Fifteen resistance-trained male subjects performed a single exercise session using 8 sets of Bulgarian split squats performed at 75% maximal force output. Maximal force output (N) was measured after every set of repetitions. Electromyographic (EMG) activity of vastus lateralis was monitored during all force trials and exercise repetitions. Repetitions per set decreased from the first to the third set (p< 0.001). Maximal force output decreased from preexercise to set 4 (p < 0.001). Electromyographic amplitudes during exercise did not change. Secondary subgroup analysis was performed based on the presence, or not, of a fatigue plateau (<5% reductions in maximal force output in subsequent sets). Nine participants exhibited a fatigue plateau, and 6 did not. Participants who plateaued performed less first-set repetitions, accrued less total volume, and did not exhibit increases in EMG amplitudes during exercise. Initial strength levels and neuromuscular demand of the exercise was the same between the subgroups. These data suggest that there are individual differences in the training session responses when prescribing based off a percentage of maximal strength. When plateaus in fatigue and repetitions per set are reached, subsequent sets are not likely to induce greater fatigue and muscle activation. High-volume resistance exercise should be carefully prescribed on an individual basis, with intrasession technique and training responsiveness continually monitored.

A Subject-Tailored Variability-Based Platform for Overcoming the Plateau Effect in Sports Training: A Narrative Review

“…There are individual differences in response to training sessions, while the percentage of maximal strength determines the prescription. Subsequent sets are unlikely to induce more significant fatigue and activation of muscle after reaching a plateau in fatigue and repetitions per set [5]. Once a plateau is reached, heavy training does not further improve the performance of older runners with many years of training.…”

“…Adaptation is a result of multiple mechanisms [1][2][3][4][5][6][7]. There is a change in the strength of the triceps brachii after training without correlation to fatigue rate (FR) or decrease in strength (DS).…”

Influência de um exercício aeróbico prévio no desempenho de força subsequente

“…Foram considerados treinados os indivíduos que conseguiram realizar uma repetição máxima no exercício supino com o peso equivalente à sua massa corporal (7) e que estivessem praticando musculação regularmente há seis meses no mínimo. Os dados referentes à caracterização destes indivíduos estão presentes no Quadro 1. considerando-se a expectativa de redução do NMR ao longo das quatro séries (4,24) . Na outra sessão, foi realizado um protocolo de treinamento da resistência aeróbica em cicloergômetro anteriormente ao treinamento de força, com duração de 20 min e intensidade de 60% potência máxima alcançada no teste de VO 2máx (W máx ) mantendo cadência de 50 rpm.…”

Investigation of Electromyography Responses Following Resistance Exercises Done with Different Contractions

“…Yorgunluk ve set tekrar sayılarında platoya ulaştıktan sonra, takip eden setlerin daha büyük yorgunluk ve kas aktivasyonu göstermesinin pek mümkün olmayacağını belirtmişlerdir. 26 Araştırmamızda da toparlanma periyodu sırasında 3-4. dk'dan sonra EMG verileri bir plato yapmaya başlamıştır. Bu da hem yük-lenme sırasında hem de toparlanma EMG verilerinin belirli bir düzeyden sonra plato yapabileceğini göstermektedir.…”