Strength is the ability of the muscle to exert force. Typically, the term strength is associated with the ability to exert maximum force during a single effort, sometimes referred to as a one repetition maximum effort (1RM). You will often see repetition maximum used in exercise instructions. Moreover, it is impossible to design a training program without defining a load. By using repetition maximum instead of defined weights, people of different abilities can use training instructions (one person would use 10-pound weights while another would use 30-pound weights, for example). Because of this it is crucial that you fully understand the idea behind this concept. We hope this article will remove any doubts you may have.

What is one-repetition maximum or 1RM?

One-rep max (1RM) is the heaviest weight that you can lift for one – and just one – repetition. In other words, you can do a maximum of one repetition only for a given weight. If for a given weight you can perform two or more repetitions means that this weight is not your one-repetition maximum. In this case you should definitely increase the weight to find out your 1RM.

For example, if the maximum weight you can lift in bench press with proper technique for only one repetition is 85 kg – this amount of weight is your one repetition maximum or 1RM for this exercise. You can think of this weight as your personal weightlifting record for a squat, bench press, deadlift, shoulder press, or any other bodybuilding exercise.

Or let’s take a look to another example. For instance, someone gives you a weight of 100 pounds (45 kg) and then asks you to perform as many repetitions as possible (with proper technique) in the bench press exercise. If you could do only one repetition, your one-repetition maximum, or 1RM, would be 100 pounds (45 kg).

As muscles become stronger in response to training, using the same load will result in more repetitions. When this occurs, it is important to increase the load, which creates the overload that is needed to stimulate further increases in strength. In other words, your 1RM will increase with time. By knowing your 1RM and tracking it, you are able to monitor your progress and effectiveness of your training program. Plus, you get positive reinforcement and a sense of accomplishment when you have a way to clearly see improvements.

What is repetition maximum target zone?

You already know that 1RM is the maximum weight a person can lift for only one repetition. It follows that a multiple of the repetition maximum, such as 8 RM, 10 RM or 12 RM, is the maximum weight the individual can lift 8, 10 or 12 times respectively. The repetition maximum (RM) is, therefore, the maximum load that a person can handle in a specific exercise for specific number of repetitions.

For example:

  • 8 repetition maximum (8 RM) – the maximal amount of weight you can lift exactly 8 times in a row before the muscle becomes too fatigued to continue (you can’t perform 9th repetition).
  • 10 repetition maximum (10 RM) – the maximal amount of weight you can lift exactly 10 times in a row before the muscle becomes too fatigued to continue (you don’t have enough strength to perform 11th repetition).
  • 12 repetition maximum (12 RM) – the maximal amount of weight you can lift exactly 12 times in a row before the muscle becomes too fatigued to continue, etc.

For instance, if an athlete can perform 10 repetitions with 60 kg in the back squat exercise, his 10 RM is 60 kg. It is assumed that the athlete provided maximal effort. If he had stopped at nine repetitions but could have performed one more, he would not have achieved a 10 RM. Likewise, if he lifted 55 kg for 10 repetitions (but could have performed more), his true 10RM was not accurately assessed because he possibly could have lifted 60 kg for 10 repetitions.

The American College of Sports Medicine (ACSM) guidelines for strength and endurance are given in multiples of RM. For example, in order to gain strength it is recommended that an individual performs resistance exercise using weights within the range of 8-12 RM, and to improve endurance using weights within the range of 10-15 RM.

Relationships between load and repetitions

Maximum resistance, generally referred to as the repetition maximum or 1RM weight load, is the heaviest resistance that you can lift one time. By definition, 100% of the 1 RM allows you to perform one repetition. As the percentage of the 1 RM (i.e., the load lifted) decreases you will be able to successfully complete more renditions.

Loads that are less than 100 percent of 1 RM will permit the number of repetitions shown in the following list.

100 percent 1RM = 1 repetition
95 percent 1RM = 2 repetitions
90 percent 1RM = 4 repetitions
85 percent 1RM = 6 repetitions
80 percent 1RM = 8 repetitions
75 percent 1RM = 10 repetitions
70 percent 1RM = 12 repetitions
65 percent 1RM = 14 repetitions
60 percent 1RM = 16 repetitions

In a study examining relationships between resistance and repetitions (Westcott 2002), 141 participants were tested to determine how many repetitions they could complete with 75 percent of their maximum resistance. The average number of repetitions performed was 10.5. However, some people performed fewer repetitions and some performed more repetitions using the same relative load. These differences are caused by genetic variations in muscle fiber makeup, and they explain in part why some people prefer lower-repetition training and others prefer higher repetition training.

Other %1 RM-repetition tables with slightly different %1RM values can be found in the literature but they vary by only about 0.5 to 2 percentage points front those provided in table above.

However, it’s clear that number of times an exercise can be performed (repetitions) is inversely related to the load lifted. The heavier the load, the lower the number of repetitions that can be performed. Eventually the load will become so heavy that an individual can perform only one repetition; this is the 1-repetition maximum (1RM).

RM in exercise instructions (training programs)

RM is an excellent tool for prescribing intensities in resistance training. There are two main ways on which this can be accomplished.

  • The use of a percentage of the repetition maximum (RM). For example, “Eight reps at 75% of 1RM”. If, for instance, the person’s 1RM on the bench press is 180 pounds (82 kilograms), then 180 pounds x .75 = 135 pounds (61 kilograms). Therefore, this person should perform eight reps of bench press using 61 kilograms.
  • The use of repetition maximum target zone. For example, “three sets of 8 RM lifts”. When a repetition maximum zone (RM target zone) is prescribed, a person uses the heaviest weight he or she can perform the exercise for the number of repetitions within the range. In this case, a person should use maximal amount of weight he/she can lift exactly 8 times in a row before the muscle becomes too fatigued to continue.

The use of the first method requires frequent 1 RM testing to ensure that accurate training resistance is used. This method may be desirable for certain strength athletes because recurrent testing is a commonly used measure of an athlete’s progress and a predictor of preparedness for competition.

For bodybuilders and other fitness enthusiasts, frequent testing of 1 RM is not convenient or often feasible. It would be too time consuming because of the larger number of exercises they typically use. For serious weight trainers, an RM target zone is the easiest way to monitor training resistance. This is depicted as 10 RM or 5 RM and refers to a resistance that limits them to that number of repetitions. As their strength increases, they simply move to a heavier weight but shoot for the same RM goal. This allows them to continually stay in the repetition range they are shooting for without the need to test their 1RM.

Safe protocol for determining the one-repetition maximum (1-RM) of a resistance exercise

Maximum weight an individual is able to lift in a resistance exercise with good form through a full range of motion = 1 RM. A 1-RM test has an increased risk of injury since it assesses the maximum amount of weight a person can lift, which many people have never encountered; therefore, it is recommended that submaximal testing protocol be used to predict 1 RM.

We can calculate 1RM indirectly by performing a 10RM for example (which is safer), then extrapolating this to what your 1 RM should be.

Here’s the procedure that will help you determine your 1RM based on your 10-repetition maximum. You will need a set of free weights and a spotter. Regardless of your skill level, always use a spotter! Also, an experienced instructor can help find your 10-repetition maximum in fewer than five trials.

Procedure:

  1. If you are new to resistance training, begin with a lighter weight.
  2. Perform a set of 10 repetitions with the light weight.
  3. Rest two to four minutes between sets.
  4. For the second set, add additional weight based on the ease with which you completed the first set. For example, if you easily lifted 225 pounds for 10 repetitions, the next increment would be large. On the other hand, if your 225-pound lift was difficult but you completed 10 repetitions, your next raise in weight would be small.
  5. Perform another set of 10 repetitions.
  6. Continue the process of performing 10 repetitions, resting, and adding weight until you discover a weight that allows only 10 repetitions. This is your 10-repetition maximum. Check this table to find your 1RM based on your 10-repetition maximum.

For example, let’s say you were able to perform 10 repetitions of a bench press using a 305-pound weight. Under the 10 repetitions column, find 305 pounds. Look left across that row to the first column (1 repetition). This weight, 415 pounds, would be your 1 RM (estimation).

About Author

Hey! My name is Kruno, and I'm the owner and author of Bodybuilding Wizard. I started this website back in late 2014, and it has been my pet project ever since. My goal is to help you learn proper weight training and nutrition principles so that you can get strong and build the physique of your dreams!

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