Over eight weeks, lifting weights with a small reserve of repetitions left in the tank produces the same total amount of work and muscle growth as lifting until complete exhaustion, suggesting that...
Mechanism
Synthesis from 1 study
Whether you stop lifting 1–2 reps before exhaustion or push until you can’t do another, you end up doing nearly the same total amount of work — and that total work is what makes your muscles grow bigger, as shown in the study with DOI 10.1080/02640414.2024.2321021. The order of exercises can shift...
Most probable mechanism
When people lift weights with 1 to 2 reps left in reserve or push to complete exhaustion, they end up doing nearly the same total amount of work over time — this total work stretches and pulls on muscle fibers just enough to turn on a molecular signal (mTOR) that tells the muscle to grow more protein and get bigger, as shown in the study with DOI 10.1080/02640414.2024.2321021.
Resistance training with controlled loads (8–12-RM) and full range of motion generates mechanical tension in muscle fibers during concentric and eccentric contractions, activating mechanosensors such as integrins and focal adhesion kinase, as demonstrated in the study with DOI 10.1080/02640414.2024.2321021.
Mechanosensor activation triggers the PI3K/Akt/mTOR signaling pathway, which increases ribosomal biogenesis and translation initiation to enhance myofibrillar protein synthesis, consistent with the mechanistic framework established in the study with DOI 10.1080/02640414.2024.2321021 and supported by Wackerhage et al. (2019) cited therein.
Training with 1- to 2-repetitions-in-reserve (RIR) and training to momentary muscular failure (FAIL) both achieve similar total repetition volume and volume load over eight weeks, as directly measured in the study with DOI 10.1080/02640414.2024.2321021, ensuring equivalent cumulative mechanical tension exposure despite differing levels of acute neuromuscular fatigue.
Net positive protein balance from sustained mechanical tension leads to sarcomere addition and increased muscle fiber cross-sectional area, resulting in measurable hypertrophy of the rectus femoris and vastus lateralis, as quantified by ultrasound in the study with DOI 10.1080/02640414.2024.2321021.
Less supported by current evidence, but not ruled out
When leg press is done before leg extension, pushing to failure fatigues the vastus lateralis more, limiting how much the rectus femoris gets worked later; stopping 1–2 reps short preserves the rectus femoris’s ability to be fully activated during leg extension, leading to different patterns of muscle growth in the same muscle group, as shown in the study with DOI 10.1080/02640414.2024.2321021.
Leg press (multi-joint) preferentially recruits and fatigues the vastus lateralis, generating high mechanical tension in this subunit, as observed in the study with DOI 10.1080/02640414.2024.2321021.
Training to momentary muscular failure during leg press impairs subsequent leg extension performance due to residual fatigue, reducing activation and tension in the rectus femoris, as measured by differential hypertrophy outcomes in the study with DOI 10.1080/02640414.2024.2321021.
Training with 1–2 repetitions-in-reserve during leg press preserves neuromuscular function for leg extension, allowing greater rectus femoris activation and hypertrophy due to its preferential recruitment during isolated knee extension, as supported by biomechanical evidence cited in the study with DOI 10.1080/02640414.2024.2321021.
Differential hypertrophy patterns emerge: greater vastus lateralis growth with failure training and greater rectus femoris growth with RIR training, as quantified by ultrasound thickness changes in the study with DOI 10.1080/02640414.2024.2321021.
Evidence from Studies
Supporting (1)
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