Are you as accurate as you think at gauging how close to failure you are?

You might recall I broke down some of the evidence around training to failure for muscle growth and strength a couple weeks ago in this newsletter. To summarize, training closer to failure leads to more hypertrophy, but doesn’t seem to improve strength gains.

if you’re looking to apply these findings to your training, a question that naturally follows is whether people can accurately guess how close to failure they are. After all, if you’re off by a lot, it becomes difficult to maximise your progress.

Enter: our meta-analysis. I had the honour of collaborating on a study on this exact topic a couple years ago.

Read time: 6-8 minutes

Take-aways

1. People are generally pretty accurate at estimating how close to failure they are.

   1. Therefore, repetitions in reserve (RIR) and rating of perceived exertion (RPE) are excellent tools for prescribing training.

2. Below 12 repetitions per set, participants underestimated themselves by a rep or less. Above 12 repetitions per set, participants underestimated themselves by ~5 repetitions or so, on average.

   1. For sets of below 12 reps, consider doing one extra rep to remedy any potential inaccuracy.

   2. For sets of above 12 reps, consider doing 2-8 additional repetitions. Due to the burn and effort involved, you’re probably feeling weaker than you really are.

3. If you want to become more accurate at estimating repetitions in reserve:

   1. Consider taking some sets to failure to anchor your estimates. Actively make guesses during the set to failure and check how accurate your guesses were.

   2. Pay close attention to velocity during the up/lifting/concentric phase of the movement. The more it slows down, despite your best intention to be explosive, the closer to failure you are.

What did we find? Well, on average, when combining the results of 12 studies, participants only under-estimated how many more repetitions they could do before hitting failure by one repetition.

In other words, if you’re doing a set and feel like you can only do 3 more reps, in all likelihood, you can probably do 4 more - not 3.

Being more experienced had relatively little impact on accuracy of prediction. In other words, beginners are about as accurate as more advanced trainees.

Accuracy improved a little the closer to failure the prediction was made. In other words, you’ll probably be more accurate if you’re one rep from failure than if you had 5+ more reps in the tank. This is also why accuracy increased when lifting heavier vs lighter weights - as you can just do fewer reps with heavier weights and are always closer to failure.

One variable that did impact accuracy was number of repetitions per set. Accuracy was generally extremely good until about 12 repetitions per set. However, above 12 repetitions per set, accuracy rapidly worsened, such that with sets of 20-25 repetitions, participants underestimated themselves by ~5 or more repetitions.

Why?

Generally, the closer to failure you go, the greater the discomfort you experience. When you’re doing 5 reps on the leg extension, you may find reaching failure very easy and straightforward. However, if you were to do a set of 25 repetitions, you’re probably more likely to end the set when the sensation of burn in the muscle or the pump become unbearable.

If you’d like to chat about this study, feel free to comment below.

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