Impacts of failure or non-failure on muscle hypertrophy and neuromuscular

In this new, quite rigorous study by @mrfitness__ et al., 18 trained individuals were divided into two groups to explore the impacts of failure or non-failure on muscle hypertrophy and neuromuscular fatigue. Each participant had one leg randomly selected for a regimen of training to momentary muscular failure (FAIL), while the other stopped short of failure (1-2 RIR).

The exercises used were the leg press and leg extension, and quad muscles thickness was then measured via Ultrasound, while neuromuscular fatigue was monitored via rep speed and repetition loss across training sets.

Interestingly, both groups achieved similar gains in muscle thickness, suggesting that training to failure may actually not be a necessity for maximizing muscle growth, provided sufficient proximity to failure (1-2 RIR).

The FAIL group also experienced greater initial neuromuscular fatigue, but with an interesting decrease over time, indicating an adaptive response to the training to failure.

Training volume was personalized, based on each participant’s prior training experience, and was adjusted midway through the study to incorporate progressive overload: overall all lifters achieved a +20% increase in volume by the end of the study.

Overall, this paper offers great insights for athletes and trainers in optimizing resistance training protocols for maximizing hypertrophy, while also considering the implications of neuromuscular fatigue and the body’s adaptive responses to different training intensities. We confirm that, when provided with sufficient tension (0-2 RIR), muscular hypertrophy can be achieved similarly. Whether or not this is true with both heavy and light loads remains to be understood (as we’be seen recently in Robinson et al., 2023), but incorporating these strategies will ensure the effectiveness of our training programs: Training across a variety of rep ranges and loading zones within these levels of effort will work great for most, and will likely offer the greatest benefits!

In any case, hats off to the researchers, and I hope I did at least a good job at summarizing the findings!