|Methods of Muscular Fitness Assessment
Jerry J. Mayo, Ph.D., Len Kravitz, Ph.D.
The association between muscular fitness and quality of life is impressive. The benefits of muscular fitness development include increases in lean body tissue, bone mineral density, connective tissue strength, anaerobic power, low-back health, and self-esteem (Neiman, 1995). Although personal trainers develop various resistance training regimens based upon the clients goals, preferences and time constraints, the initial step (after equipment familiarization) should be to establish a baseline level for overall muscular fitness. This would include tests for muscular strength and muscular endurance. The most important reason for monitoring muscular fitness is for program/client evaluation and the progression of the resistance training program (Kramer & Fry, 1995). The purpose of this article is to discuss appropriate methods of muscular fitness assessment for the personal trainer.
What is your Goal? Strength or Endurance
Muscular strength is the ability of a muscle or muscle group to generate maximal force, whereas, muscular endurance describes the muscles ability to exert successive submaximal force for a certain period of time. Initially, personal trainers need to determine whether to test for strength or endurance, and then select the appropriate assessment. Strength and endurance are specific to the muscle group, speed of the contraction, type of contraction, and joint angle being tested (Heyward, 1991). For optimal measurement and assessment, the testing should be very similar to the muscular fitness training.
Muscular Strength Testing
Repetition Maximum Testing
The gold standard for muscular strength testing is the 1 RM. Kramer and Fry (1995) suggest the following protocol for 1 RM testing. The test procedure begins with a warm-up of 5-10 repetitions at 40% to 60% of the clients estimated maximum. After a brief rest period, the load is increased to 60% to 80% of the clients estimated maximum, attempting to complete 3-5 repetitions. At this point a small increase in weight is added to the load and a 1 RM lift is attempted. The goal is to determine the clients 1 RM in 3 to 5 trials. The client should be allowed ample rest (at least 3-5 minutes) before each 1 RM attempt. Kramer and Fry emphasize that ongoing encouragement and communication with the client during this testing is crucial to obtain the best performance.
Obtaining the clients maximum load capabilities may serve one of the following purposes: 1) to establish the load settings for an initial exercise prescription, 2) to determine the progress of a current resistance training program, or 3) to rank clients muscular strength based on standard norms. If the intent is to classify muscular strength, in relation to total body weight, divide the total amount lifted (lbs) by the clients body weight (lbs). Standard norms (see Tables 1-4) are used to evaluate this relative strength ratio. For example, a thirty year-old female (weight = 130 lbs) has a 1 RM leg press of 150 lbs. Her ratio would be 1.15 (150 lbs/130 lbs = 1.15) which is a rating of Fair.
The most widely used exercises for upper and lower body muscular strength testing are the bench press and leg press, respectively. Other dynamic strength tests include the arm curl, latissimus dorsi pull down, knee extension and knee curl. Norms for assessing the combined total of these strength measures, by calculating a point score for each measure, are presented in Table 5 (Heyward, 1991).
Prediction of 1 RM Testing
Muscular strength testing is not limited to 1 RM testing. A prediction equation has been developed using up to a 10 repetitions (See Figure 1) (Brzycki, 1993). This method of 1 RM estimation describes the mathematical relationship between the number of reps performed to fatigue (failure must occur at 10 repetitions or less) and the actual 1 RM. Therefore, you can select any number up to 10 RM for the prediction (e.g., 4 RM, 5 RM or 6 RM) of the clients 1 RM. Table 6 shows predicted 1 RM from various weight and repetition combinations. For example, lifting a 75 lb weight for 9 repetitions estimates the 1 RM to be 96 lbs.
The personal trainer may find the estimation (of 1 RM) method a more practical, and certainly safer, alternative to maximal exertion testing. Factors such as age, current training status, physical limitations, and fitness goals will help define the most appropriate test protocol.
Testing procedures for a 10 RM (or less) are similar to that of the 1 RM test. Begin by allowing the client to warm up with 10 repetitions with 50% of the estimated 10 RM. Then attempt a 10 RM lift at 60% to 80% of estimated maximum. It is desirable to achieve a 10 RM maximum on the next load increase if possible. Since the testing volume is greater for the 10 RM than the 1 RM, fatigue will undoubtedly affect the outcome. When using this prediction testing method, allow for sufficient rest between sets (3 to 5 minutes or more), maintaining a strong communication with the client. Retesting after a 24 hr rest may be necessary if it appeared that fatigue impaired the clients performance.
Muscular Endurance Testing
Muscular endurance may be measured using a fixed percentage of a person's body weight, a fixed percentage of a one's 1 RM, an absolute weight, or calisthenic-type exercises. However, good norms have yet to be established with most of these types of test protocols. In addition, since there is a broad variation in exercise equipment design, it would be difficult to establish comparison norms for individuals who test on the different equipment.
Fixed Percentage of a Persons Body Weight Method
As a model for determining a fixed percentage of a persons body weight, Table 7 presents some published guidelines (Heyward, 1991). First determine the clients body weight in pounds. Then calculate the amount of resistance for each lift by multiplying the body weight by the percentage of each lift. For example, a 150 lb male on the leg extension would perform this test using 75 lbs (150 X .50 = 75 lbs). Have the client perform the maximum continuous number of repetitions. This test protocol is best used to track the clients muscular endurance changes over time.
Fixed Percentage of Persons Body Weight
Percent of Body Weight
Exercise Men Women
Lat Pull-Down .66 .50
Leg Extension .50 .50
Bench Press .66 .50
Leg Curl .33 .33
Arm Curl .33 .25
Adapted from Heyward, V. H. (1991). Advanced fitness assessment
& exercise prescription (2nd ed.). Champaign, IL: Human Kinetics.
Fixed Percentage of a One's 1 RM Method
With the fixed percentage of ones 1 RM method, usually 70% of the clients 1-RM is preferable (Nieman, 1995). For example, a client with the maximum bench press of 150 lbs. would use 105 lbs. for the muscular endurance test. Again, due to a lack of established norms, the number of successful lifts may be used as a marker to assess gains in muscular endurance. An added value to the trainer when using this endurance method is to evaluate the emphasis of the clients resistance program. For example, ten successful lifts completed during the initial test and seven repetitions completed in a subsequent assessment could be an indication that muscular strength may be improving faster than muscular endurance (Franks & Howley, 1989).
With the absolute method, muscular endurance is assessed by counting the number of successful repetitions of a "fixed" load over time. This type of testing is very important in fields such as fire-fighting and construction, where being able to repeatedly lift certain loads is necessary for the job (Nieman, 1995). The disadvantage of this method is that it does not take into account a persons body weight. For a published example of an absolute weight test using the bench press, the trainer is referred to the YMCA Bench Press Test (Golding, Myers, & Sinning, 1989)
Muscular endurance tests using calisthenic-type exercises are convenient to use. The curl-up and push-up are the most common calisthenic-type muscular endurance tests used by fitness professionals.
The curl-up (for abdominal muscle endurance) has been suggested as an alternative to the sit-up due to dissatisfaction with the involvement of the hip flexors when performing a sit-up motion (Neiman, 1995). Steps to perform this test include the following: Start supine with the arms extended by the side, palms facing the floor, and fingers extended. The knees are bent at a 90° angle. With the fingers, feet and buttocks on the floor, the client performs a curl-up reaching forward (towards an established end-line) with the arms approximately 4.75 inches (3 inches if over 40 years of age) along the floor. The curl-up is performed at a cadence of 50 bpm. Terminate the test when the client: 1) cannot maintain the cadence, 2) performs the curl-up with improper technique, or 3) performs 80 repetitions.
The purpose of push-up test is to measure upper body muscular endurance. The standard and modified push-up are often used. For clients who cannot do up to 8 standard push-ups, the modified push-up is recommended. Start in a supported push-up (or modified with the knees down) position. Lower chest to the floor and return to the starting position. The client performs as many continuous push-ups as possible without stopping.
Assessment Equipment: Free Weights Vs. Resistance Machines
Methods of assessing muscular fitness are based on factors which include muscle groups to be tested, availability of equipment and cost. For personal trainers, free weights and various types of resistance machines are most commonly used for muscular strength and endurance assessment. The biggest difference between these two modalities of muscular assessment are that free weight exercise requires more motor coordination and balance resulting in greater muscle recruitment. Free weight exercises employ important stabilizing muscles to complete a lift, compared with machines which do not emphasize the stabilizing musculature because movements occur in only one plane of motion. Free weights also allow the personal trainer the freedom to test different exercise variations compared to resistance machines. Compared with free weights, resistance machines offer a convenient, safe and easy way to test muscular fitness (Garhammer, 1987).
An aspect for reliable muscular fitness testing often overlooked is exercise technique. Prior to each exercise assessment clients should be instructed on proper technique including body position, and starting and stopping points of each movement. For consistent results strict testing procedures should be followed.
Safety is a concern for anyone actively involved in fitness assessment. Communication between the personal trainer and the client is a big key to injury prevention during testing. To insure safety of the participant, it is also imperative to use spotters when testing 1-RM with heavy loads on free weight equipment.
One normal physiological consequence of resistance exercise is increased blood pressure. However, intrathorasic pressure can be intensified by breath holding (the valsalva maneuver) during the concentric phase of the lift (ACSM, 1995). By instructing clients to exhale on the concentric phase and inhale on the eccentric phase of the lift, blood pressure should remain within a safe range.
Additional Test Considerations
Other circumstances affecting the assessment process include testing environment and client motivation. Muscular fitness assessment should take place in a comfortable atmosphere where the client is able to focus only on the upcoming lifts. If the room temperature is too hot or distractions are present, a less than maximal test may result.
Clients will not always be motivated to give a maximal effort during muscular fitness assessment. Motivation of the participant may be improved by enthusiastically encouraging the client to provide maximal effort.
Muscular fitness assessment is beneficial for both personal trainers and their clients. By following the guidelines described in this article, personal trainers can remove much of the guesswork of exercise prescription, and provide sensible starting and progressing points for resistance training programs. With follow-up evaluations, clients will see measurable improvement that may help them maintain interest in the program.
ACSM (1995). Guidelines for graded exercise testing and prescription (5th ed.). Baltimore, MD: Lea & Febiger.
Bryant, C. X. & Peterson, J. (1995). Measuring strength. Fitness Management. 11: 32-37.
Brzycki, M. (1993). Strength testing - predicting a one-rep max from reps to fatigue. Journal of Physical Education, Recreation and Dance. 64: 88-90.
Franks, B. D. & Howley, E. T. (1989). Fitness leaders handbook. Champaign, IL: Human Kinetics.
Garhammer, J. (1987). Strength training. New York, NY: Winners Circle Books.
Golding, L. A., Myers, C. R., Sinning, W. E. (1989). The Ys way to physical fitness (3rd ed.). Champaign, IL: Human Kinetics.
Heyward, V. H. (1991). Advanced fitness assessment & exercise prescription (2nd ed.). Champaign, IL: Human Kinetics.
Kraemer, W. J. & Fry, A. C. (1995). Strength testing: development and evaluation of methodology. In P. Maud & C. Nieman, D.C. (1995). Fitness and sports medicine: A health-related approach (3rd ed.). Palo Alto, CA: Bull Publishing.