A new study on training to failure shows that you may not need to train to failure to maximize gains!
Overview
What did they test? The study compared the effects of resistance training to muscular failure versus with repetitions-in-reserve on muscle growth and fatigue in trained individuals.
What did they find? Both training approaches produced similar muscle growth over eight weeks, but training to failure induced higher acute neuromuscular fatigue.
What does it mean for you? You can achieve similar muscle growth whether you train to failure or leave a few reps in reserve, but training to failure may lead to more fatigue.
What’s the Problem?
Here we go again! As you are probably aware by now, lifting is the best way to grow muscle and we’ve previously touched on previous issues of REPS even sets that are terminated away from failure can result in muscle growth. However, when looking at getting properly jacked (to put it scientifically), training with a high intensity of effort seems to be non-negotiable. Despite this being a relatively straightforward principle, proximity to failure and muscle gains remains a hotly debated topic within the sports science and lifting community 1. In a previous issue of REPS we reviewed a recently pre-printed study by Robinson et al 2 which looked at the effect of proximity to failure and muscle gains.
Let me refresh your memory as far as the findings of the Robinson et al paper go:
“Overall the results of the authors’ analyses showed that strength gains are minimally affected by proximity to failure while hypertrophy gains seem to increase non-linearly as one gets closer to failure. In other words, muscle growth seems to increase as one gets closer to failure, with the best gains observed somewhere around 0-2RIR.”
Under the “How Can You Apply These Findings?” section I had noted the following:
“The main takeaway for hypertrophy here is that training very close or to failure is probably a really good idea. Although the findings of this review slightly changed my perspective, making me more inclined to prescribe more sets to failure, especially for trainees who have a habit of underpredicting their proximity to failure, the practical takeaways are in line with what we’ve recommended in the past. However, the findings of this review do highlight the importance of training extremely close to failure (0-2RIR) and that sets at greater proximities to failure (eg: 4RIR) may be actually resulting in meaningfully less hypertrophy for those interested in maximizing hypertrophy. It may therefore be wise to aim for 0RIR for the majority of your working sets (>60% of volume performed) and keep the rest of your training around the 1-2RIR mark.”
For clarity’s sake (and any new readers) allow me to note that proximity to failure during resistance training is typically measured by repetitions-in-reserve (RIR), which is the number of repetitions one can still perform before reaching muscular failure—the point at which no more repetitions can be completed with good form due to fatigue. While it's widely accepted that training should be carried out with a high level of effort, aka very close or to muscular failure, to maximize muscle growth, the necessity and efficiency of reaching or avoiding momentary muscular failure for optimizing hypertrophy are subjects of ongoing debate, something that was further fuelled by the Robinson et al pre-print.
The paper by Robinson et al analyzed the current literature by performing a series of meta-regressions with the leading author noting that:
“While there are a few important limitations to keep in mind (e.g., potentially inaccurate RIR estimations), the implications of this analysis can be simplified into one statement; you have to train hard to optimize gains in strength and size.”
