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1 RM Strength Testing
By Len Kravitz, Ph.D., Kenneth Nowicki, M.S., and Stephen J. Kinzey, Ph.D.

The use of repetition maximum testing (1 RM) is often used by athletic trainers, health and fitness professionals and rehabilitation specialists to quantify the level of strength, assess strength imbalances, and to evaluate training programs (Braith, Graves, Leggett, & Pollock, 1993). Early research on 1 RM testing dates back to 1955 and has developed to be a reliable assessment of maximal strength (Hoeger, Hopkins, Barette, & Hale 1990). However, the extreme efforts from musculoskeletal loading in 1 RM testing may not be recommended for some populations, including the elderly, cardiac patients, adolescents, and some sedentary populations. For these populations and even the recreational enthusiast population, other options include 1 RM prediction equations or repetition maximum zone testing (Fleck & Kraemer, 1998).
It is important to identify the component of muscular fitness you are testing with a client. Research suggests that exercises performed at an intensity attaining the RM in a range from 1 to 10 repetitions is testing primarily for strength, whereas RMs over 12 repetitions are assessing muscular endurance (Fleck & Kraemer, 1998). Regardless of the emphasis of the training program, there are some caveats the personal trainer should be aware of in repetition maximum testing.

Importance of Technique
Original research recently completed by the authors suggests that performance technique has a substantial effect in strength testing. This investigation completed submaximal and maximal testing procedures with elite high school powerlifters (two-time national and two-time world champions) using 3 certified AAU judges present to make sure adherence to competition guidelines were correctly followed on all lifts (squat, bench press and deadlift). Early data analysis indicates that established prediction equations are inadequate in predicting maximal strength in this population. We believe this is due to the fact that the testing standardization of previous investigations did not follow competition guidelines. However, the practical application to the personal trainer is quite relevant. When doing all single joint and multi-joint exercise testing, strict adherence to testing guidelines is a necessity. Key areas to standardize include the following: (1) equipment used, (2) body position before and during the exercise performance, (3) starting and ending point of motion, (4) cadence of motion, (5) use or non-use of pause points during set, (6) warm-up prior to test, (7) performing technique of exercise, (8) clothing worn for testing, (9) time of day of testing, (10) energy level of client, (11) motivation of client towards testing, (12) nutritional status of client, (13) adequate rest between testing trials, and (14) attainment of momentary muscular fatigue. Without strict attention to the above, the ability to progress and properly use periodization techniques for the client will be impaired.

Importance of Training Technique
Previous research suggests that maximal bench press strength is highly correlated to upper arm cross-sectional area, % BF, and chest circumference. However, our study found no biometric variables to be highly correlated to bench press, squat or deadlift strength. Our findings show that years lifted is more highly correlated with maximal strength in the bench press and dead lift exercises, but not the squat. This suggests that training technique, with a complex movement such as the squat, is a more significant component to strength gains. This is substantiated by the fact that this population of world-caliber athletes trained with the same strict performance adherence used in competition.

Prediction Equations of 1 RM
It is interesting to note that although 1 RM testing is used for a number of applications previously mentioned, there are few sports (e.g. powerlifting) that actually require 1 RM for performance. There currently are several equations that predict 1 RM strength from a certain number of repetitions and weight lifted. The use of 1 RM prediction equations has been utilized when trainers attempt to design weight training programs based on a percentage of the client’s 1 RM, thus determining how much weight the client should be lifting. However, most prediction equations have been established from one or two exercises, usually the bench press and the squat, and may not be suitable to other exercises. This is substantiated by research by Hoeger (1990) who had subjects perform 40, 60, and 80 percent of the 1 RM in the (1) arm curl, (2) knee extension, (3) bench press (4) sit-up, (5) leg curl, (6) lateral pulldown, and (7) leg press. Results showed that the number of repetitions at these selected percentages of a 1 RM was different for each exercise. This research suggests that submaximal tests can not be generalized to predict 1 RM from one exercise to another. Our research with the squat, bench and deadlift concurs that separate prediction equations are more accurate for selected exercises. So what is a workable option for the personal trainer committed to doing appropriate strength assessments and yet not wanting to overstress (1 RM testing) the musculoskeletal system of the client, or error with prediction equations?

Repetition Maximum Zone Testing
Fleck and Kraemer (1998) suggest the use of repetition maximum zone for testing can be most useful in assessing muscular fitness and applicable for designing the resistance training program. The use of the appropriate zone can be determined by the goals of the muscular fitness program or the period of training the client is in (See Table 1). Say, for instance, the attribute you targeted for the deltoids was moderate heavy strength. You determined that your client could lift 80 lbs in 7 repetitions (following the stringent guidelines identified above). If in 8 weeks the client can lift 90 lbs in 7 repetitions on the same exercise that indicates a 12.5% increase (10 lb/80 lb = 0.125) in load lifted. If you prefer, keep the weight the same and see how many more repetitions the client may do. For instance, in the above example lets assume the client after 8 weeks can do 9 repetitions. That would represent a 28.5% increase in repetitions (2/7 = 0.285).
Perhaps the best reason for repetition maximum zone testing is the safety advantage, both physically and mentally, to your clients. One of the ideals of any personal trainer is to accurately monitor a client’s progress, in a meaningful and non-invasive manner. Another advantage of the repetition maximum zone testing is how you can readily individualize the testing for different muscle groups. The final outcome will hopefully help motivate your clients to adhere enthusiastically to their resistance training program.

Table 1. Repetition Maximum Zone Testing
Zone Attribute
1-3 RM Very heavy strength
3-6 RM Heavy strength
6-8 RM Moderate heavy strength
8-11 RM Moderate intensity
12 RM and higher Endurance
Adapted from Fleck and Kraemer (1998). Strength and Health Report, 2, 1,2.

Braith, R. W., Graves, J. E., Leggett, S. H., & Pollock, M. L. (1993). Effect of training on the relationship between maximal and submaximal strength. Medicine and Science in Sports and Exercise, 25, 132-138.
Fleck, S. J., & Kraemer, W. J. (1998). Repetition maximum methods for monitoring your weight training intensity. Strength and Health Report, 2, 1,2.
Hoeger, W. W. K., Hopkins, D. R., Barette, S. L., & Hale, D. F. (1990). Relationship between repetitions and selected percentages of one repetition maximum: A comparison between untrained and trained males and females. Journal of Applied Sport Science Research, 4, 47-54