Global recommendations on physical activity and health of youth now support regular participation in muscle strengthening activities (10). Despite outdated concerns that resistance training was unsafe or potentially injurious to the developing musculoskeletal system of school-aged youth, available evidence indicates that resistance training can be a safe, effective, and worthwhile activity for children and adolescents provided that age-related training guidelines are followed and qualified instruction is available (2,6). However, methods for evaluating muscular strength and power in younger populations remain contentious. Although 1 repetition maximum (RM) testing can be used to assess muscular fitness in school-aged youth (2,6), some observers are concerned about the impact of high-intensity loading on the developing musculoskeletal system (1). The purpose of this article is to present a new paradigm for safely instituting maximal strength testing in children and adolescents through criterion competency assessments.
RM testing is used in school- and community-based programs to track progress, develop personalized programs, provide motivation, and assess the effectiveness of a fitness program (8). However, proper administration of maximal strength and power testing requires qualified instruction and consistent feedback on the technical performance of every repetition during the testing session. Although field tests, such as the standing long jump or vertical jump, may provide a general index of lower body power, RM testing can provide valuable information regarding absolute and relative changes in strength and power performance and the effectiveness of a training cycle.
Resistance exercises, such as the back squat, bench press, and power clean, are commonly used to assess strength and power. Although the safety, efficacy, and reliability of 1RM strength and power testing in children and adolescents have been established (3,4), it is important to underscore the importance of properly administering RM testing procedures when assessing strength and power in younger populations. Unlike most adults, children and adolescents typically have limited experience performing maximal strength and power tests. Moreover, without qualified instruction and supervision, youth may be at increased risk of injury because of accidents and unsafe behavior (7).
To assess muscular fitness in a safe and efficacious manner with a focus on correct exercise technique, we use an approach called criterion repetition maximum (CRM) testing. Although all RM testing require proper exercise technique and qualified supervision, CRM testing is a method of assessing strength and power that focuses on the technical performance of a maximal or near-maximal lift using accepted commonalities of resistance exercise performance as criterion measures. The perception of a CRM as opposed to an RM helps to reinforce the importance of maintaining proper exercise technique and better illustrates the significance of movement pattern efficiency as the criterion measure. This concept is particularly important for young lifters who may approach RM testing with a pass/fail mentality. Consequently, it is important that young lifters understand that the amount of weight lifted is not as important as how well the weight is lifted. As such, CRM testing procedures can serve as a pedagogical tool for reinforcing proper technique and resistance training methods.
Of note, before CRM testing, participants of any age should have the technical competency to perform the test exercise properly. Selected strength tests should be consistent with each participant's training status because a less-skilled individual may have technical difficulties performing an exercise, which could limit performance and increase the risk of injury. Familiarization and practice are particularly important for untrained youth who need to develop basic movement competencies and receive instruction on safety concerns before strength testing (2).
CRM TESTING PROCEDURES
Qualified professionals who have an understanding of youth resistance training guidelines should administer CRM test procedures. Furthermore, professionals should have experience in testing youth and should genuinely appreciate the physical and psychosocial uniqueness of younger populations. All 1RM testing require a systematic progression in test load until the maximum resistance that can be lifted properly for one repetition is determined, whereas predictive methods require load-specific achievements of predetermined repetitions. CRM testing differs by focusing on the quality of the movement and the physical effort required for performing the lift, which requires testers to carefully assess the technical performance of every repetition and closely monitor the response of each individual to the testing protocol.
Based on the specific testing criteria for each exercise, youth are given specific feedback related to their technical performance and behavior. The 4 levels used to assess performance are developing (D), capable (C), basic (B), and advanced (A). It is expected that participants will be able to perform at the “C” level, which reflects average performance or minimal competency. The “B” level reflects a higher level of confidence and understanding of resistance exercise, whereas the “A” level is indicative of exemplary lifting performance, a remarkable understanding of skills, and a genuine commitment to improving personal fitness. The “D” level indicates that the individual performed a skill improperly or did not follow safety rules. Because this type of analytic rubric identifies the technical and the qualitative characteristics of resistance exercise performance, participants are able to reflect on their own performance, and coaches can use this information to plan meaningful learning experiences that are consistent with individual needs and abilities. When used appropriately, a grading rubric for CRM testing can provide participants with the knowledge, skills, and understanding to demonstrate what they can do now that they could not do before.
Before attempting a CRM, subjects should perform a progressive series of submaximal sets of 1–5 repetitions with moderate to heavy loads (∼50 to 90% of the estimated CRM). Weights prescribed for warm-up sets and testing can be based on a subject's previous lifting experience or previous CRM test results. For example, if an untrained 12-year-old boy had a 1 CRM of 40 kg (88 lb) on the bench press exercise at the start of a fitness program, his estimated 1 CRM after 2–3 months of resistance training would be about 50 kg (110 lb). This assumes that a qualified professional properly instructed and sensibly progressed his training loads based on the technical competency and skill development. Therefore, during the CRM testing session, his warm-up sets should begin with 25 kg and progress to 30, 35, 40, and 45 kg. If the weight is lifted with proper form, he can attempt a 1 CRM with 47.5 kg. Pending approval from the coach or teacher, the weight can be increased by approximately 2.5 kg for another 1 CRM trial with 50 kg after an adequate rest interval (about 2 minutes). The increments in weight should be dependent on the effort required for the lift and should become progressively smaller as the subject approaches the 1 CRM. Each subject's 1 CRM should be determined within 3–5 trials, although additional trials may be needed if the estimated 1 CRM was underestimated. The CRM is recorded as the maximum resistance that can be lifted for the desired number of repetitions (e.g., 1 or 10 CRM) using proper exercise technique with appropriate physical effort.
The process of increasing the weight to a true 1 CRM can be enhanced by previous exposure to the testing exercise. This experience is important, as it will provide the lifter with an opportunity to practice proper technique and demonstrate needed proficiency in the desired movement. The technical competency of the lifter can influence the progression or regression of the CRM weights and the outcome of the assessment. Professionals should provide encouragement and reinforce the importance of proper exercise technique. Throughout the testing session, participants should be queried for a subjective assessment of the load lifted and their willingness to continue. A child-specific perceived exertion rating scale can be used during strength testing to assist in the progression of the weight lifted during CRM trials (5,9).
An example of CRM testing procedures for the bench press exercise is outlined in the Table. Although the practical aspects of performing the bench press exercise have been previously described (8), the testing guidelines outlined on the Table highlight the technical skills required to perform this exercise with proper skill, effort, and attitude. However, it must be understood that qualified professionals who have experience teaching resistance exercise to school-aged youth should administer testing procedures and properly assess performance (e.g., A, B, C, or D) in the Level column for each skill.
Because strength and power are key components to a physically active lifestyle, there is growing interest in strength and conditioning in schools, fitness centers, and sport training facilities. When appropriate, CRM testing can be performed to monitor pre/post-changes in muscular strength and determine whether a real change in performance has occurred. In addition, CRM testing can be used to educate young lifters about proper exercise technique, raise awareness about common technical flaws, and provide teachers with an evidence-based tool for assessing learning in physical education. Substantive and consistent instruction and supervision are critical to achieve highly reliable test results safely and efficaciously. CRM testing can be considered an educational testing protocol for children and adolescents, provided practitioners have experience teaching school-aged youth and measuring parameters of muscular strength.
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© 2014 by the National Strength & Conditioning Association
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