Some researchers believe some sets should be taken to complete muscular failure, while others believe you should stop just short of failure. Lifters use what is called repetitions in reserve (RIR), which is the number of reps away from failure or reps left in the gas tank.
The Science Behind Reps in Reserve: How It Affects Your Muscle Growth SUMMARY
- Reps in Reserve are a valuable way of measuring workout fatigue during a training plan.
- Sets do not need to take sets to complete muscular failure; studies have shown that stopping short of muscular failure results in similar muscle growth.
- Most sets should be stopped with 1-2 reps before muscular failure for optimal increases in muscle growth.
WHAT DOES RPE MEAN IN LIFTING?
RPE stands for the Rate of Perceived Exertion (RPE). People can gauge exercise intensity on a scale of 1-10. RPE can be used for measuring exercise intensity levels during running and HIIT training. If you are sprinting and, let’s say, you could possibly run for 2 more seconds, that would correspond to an RPE 8.
You may hear people talking about using an RIR scale while lifting (For example, RIR 3). What does RIR mean? RIR stands for Repetitions in Reserve RIR) and was explicitly designed for weightlifters. RIR measures how many reps you could have done before reaching complete muscular failure.
REPS IN RESERVE (RIR) VS RPE
RPE vs RIR are used interchangeably to measure the intensity of exercise, but there are differences. RPE is a broad range of gauging exercise effort, whereas reps in reserve (RIR)is a more accurate way of gauging effort. For example, some people can tolerate more pain during exercise. Two people can both be at an 8 during exercise (i.e. 1-10 exercise exertion level), and one can last longer, whereas the other will stop very shortly. In an RIR, you are gauging the number of repetitions you could have possibly done before technical failure (i.e., complete muscular failure).
RIR or Repetitions in Reserve and RPE basically measure exercise intensity levels, but reps in reserve is specific to weightlifting and bodybuilding. For example, in weightlifting, two people’s 8 RPE can be very different. For example, a beginner just starting to lift a weight will feel he is at an 8 if effort level, but in reality, he is at a 6. A very useful tool is an RPE calculator to measure what 1 RM percentage (i.e., rep max).
Reps in reserve is a more useful gauge because it measures how many repetitions they could have performed before reaching failure. RIR is a more useful approach to gauging effort levels during resistance exercise.
10/19 RESEARCH UPDATE: YOU CAN TRAIN FURTHER AWAY FROM FAILURE THAN PREVIOUSLY THOUGHT AND STILL MAKE STRENGTH GAINS!!!
The newest research suggests that you can train further away from failure and still gain strength. Training to failure is associated with more neuromuscular fatigue and less gains in strength. The research on velocity-based training has found that training further away from failure is better for strength gains, whereas training closer to failure is better for muscle growth.
REPS IN RESERVE STUDY
An exciting abstract was recently published, which suggests that you can train further away from failure than previously thought. Researchers took 14 resistance-based males and divided them into two groups of squats:
A.) One group trainer with an RIR (Reps in Reserve) of 4-6,
B.) The other group trained with an RIR of 1-3.
RIR is an indicator of how close to muscular failure you are training. If you are training with an RIR of 1-3, this means you are training at a relative intensity in which a person is 1-3 reps away from muscular failure. Most lifters would suspect that the group training further away from failure would gain less strength, but that’s now what the researchers found.
The group that trained with a 1-3 RIR or those that trained closer to failure trained at a higher intensity and performed more repetitions (i.e., higher volume), but strength gains were similar between groups. The researchers found you can make similar strength gain training further away from failure (i.e., 4-6 reps away from failure) compared to those that train closer to failure (i.e., 1-3 reps away from failure.). The full article is yet to be published, but this research aligns with other research suggesting that if strength gains are your main goal, limit the number of sets in which you are training to failure. If you are involved in sports, you can maintain your strength throughout the season while training further away from failure.(12)