For people who regularly lift weights, training with a little bit of effort left in the tank (1–2 reps before failure) produces the same total amount of work and number of repetitions over eight...
Mechanism
Synthesis from 1 study
Lifting weights with 1 to 2 reps left in the tank lets you do just as many total reps and lift just as much weight over eight weeks as pushing to failure, because you don’t get as tired too fast — and that same total amount of work on your muscles leads to the same growth, as shown in the study...
Most probable mechanism
When people lift weights with 1 to 2 reps left in the tank instead of going all the way to failure, they don’t get as tired right away, so they can do more reps across all sets without slowing down too much — this lets them lift about the same total weight over time as those who push to failure, and that similar amount of pulling and pushing on the muscles leads to the same muscle growth, as shown in the study with DOI 10.1080/02640414.2024.2321021.
Resistance training with 1- to 2-repetitions-in-reserve limits acute neuromuscular fatigue compared to training to momentary muscular failure, preserving movement velocity and repetition capacity across sets, as directly measured in the study with DOI 10.1080/02640414.2024.2321021.
By maintaining higher repetition performance across multiple sets, training with 1- to 2-RIR achieves total volume load and repetition accumulation equivalent to training to failure, as confirmed by direct measurements of volume load and repetition count in the study with DOI 10.1080/02640414.2024.2321021.
Equivalent total volume load and repetition accumulation expose muscle fibers to similar cumulative mechanical tension during concentric and eccentric phases, activating mechanosensors such as integrins and focal adhesion kinase to trigger the PI3K/Akt/mTOR signaling pathway, as inferred from the study with DOI 10.1080/02640414.2024.2321021 and supported by established mechanistic literature cited therein.
Sustained mTOR signaling increases ribosomal biogenesis and myofibrillar protein synthesis, resulting in net positive protein balance and structural growth of muscle fibers, as directly measured by increased muscle thickness in the rectus femoris and vastus lateralis after eight weeks 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 on the first exercise makes the quadriceps too tired to fully activate the rectus femoris during the second exercise, but stopping 1-2 reps short preserves its activation — leading to different patterns of muscle growth in different parts of the thigh, as shown in the study with DOI 10.1080/02640414.2024.2321021.
Performing multi-joint exercises (e.g., leg press) before single-joint exercises (e.g., leg extension) causes greater fatigue in the vastus lateralis during the first exercise, reducing subsequent activation of the rectus femoris during leg extension in the failure protocol, as observed in the study with DOI 10.1080/02640414.2024.2321021.
Training with 1- to 2-RIR on the leg press reduces fatigue accumulation, allowing higher-quality leg extension performance and greater activation of the rectus femoris, which is preferentially engaged during isolated knee extension, as supported by biomechanical evidence cited in the study with DOI 10.1080/02640414.2024.2321021.
Differential mechanical tension exposure across quadriceps subunits leads to region-specific hypertrophy: greater vastus lateralis growth with failure due to maximal tension during leg press, and greater rectus femoris growth with RIR due to preserved activation during leg extension, as measured by ultrasound in the study with DOI 10.1080/02640414.2024.2321021.
Evidence from Studies
Supporting (1)
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