When performing sustained muscle contractions at 30% of maximum strength, both low and high repetition resistance training lead to similar increases in electrical signals from motor units as the...

We analyzed one assertion on how low and high RIR resistance training affects motor unit activity during sustained isometric contractions, and the evidence we’ve reviewed so far suggests that both approaches lead to similar changes in the electrical signals from motor units when contracting at 30% of maximum strength [1]. As the muscle fatigues, the nervous system appears to recruit more powerful motor units in both cases, regardless of whether the training was performed with low or high repetition schemes. This pattern implies that, under these specific conditions, the body’s strategy for maintaining force output may not differ significantly between the two methods. We did not find any evidence contradicting this observation. The single assertion we reviewed was supported by the data provided, but it is important to note that this conclusion is based on only one assertion, and the context is limited to a single intensity level — 30% of maximum strength — during sustained contractions. We do not know if this pattern holds at higher intensities, during dynamic movements, or over longer training periods. What this means for someone training is that, at least during a steady, low-force hold, the way your muscles and nerves work together may look similar whether you’re doing fewer reps with more effort or more reps with less effort. But this doesn’t tell us which approach is better for building strength or muscle over time — only how motor units behave during one type of contraction under one specific condition. Our current analysis is limited, and more research would help clarify whether this similarity extends beyond these narrow conditions.