To our knowledge, no other study has examined the reliability of 1 RM power clean testing in young lifters. Results of this investigation indicate that 1 RM power clean testing has a high degree of reliability in trained male adolescent athletes when standardized testing procedures are followed and qualified instruction is present. No untoward responses or injury occurred from 1 RM testing procedures. Despite previous concerns associated with 1 RM power testing in youth (2
), our findings support the updated NSCA paper on youth resistance training and indicate that the maximal muscular power of healthy trained adolescences can be assessed with the 1 RM power clean (9
). However, it must be underscored that subjects in this study were trained adolescent athletes who had experience performing weightlifting exercises and all procedures were administered by qualified professionals who were knowledgeable of pediatric resistance training guidelines and the pedagogical aspects of teaching weightlifting to school-age youth. The findings of this study may not be generalizable to untrained youth, or to cases in which test protocols are administered by inexperienced professionals.
Although data on 1 RM test-retest reliability in younger populations are limited, our data are consistent with previous reliability assessments performed on adult athletes. For example, McGuigan and Winchester reported an ICC of 0.98 for 1 RM power clean testing in American football players (21
). Since the ICC is a measure of relative reliability that examines the consistency of individual scores (32
), the observed ICC of 0.99 in the present investigation indicates that power clean testing is a highly reliable measure in trained adolescents. We previously reported ICCs of 0.93 to 0.98 for the 1 RM chest press and leg press tests in children (8–12 yrs) (12
) and others reported high ICCs on a variety of upper and lower body 1 RM strength tests in adults (20
). Of potential relevance, ICCs ≥ 0.90 have been found in children who performed sports-related tests of speed and agility and in adolescents who performed the drop vertical jump (1
). Researchers have used the 1 RM power clean to assess performance in adolescents and a recent survey of high school coaches revealed that “Olympic style lifts” and its variations were the most important exercises these coaches prescribed for their athletes (6
). Of note, data indicate that the risk of injury during the performance of weightlifting movements during training or competition is relatively low provided that qualified instruction is available and safety measures are in place (5
The Bland-Altman plots presented in show that the limits of agreement is small, suggesting that individual variability between 1 RM trials was negligible in our subject population. The Bland-Altman plot also confirmed that there was no systematic shift (i.e. learned effect) between 1 RM test sessions. The lack of association between difference and average also confirm that these methods do not provide systematic error. Moreover, linear regression (between the difference and the average) indicated an r-square of 0.00003 which represents cumulative and strong evidence that the 1RM test methods employed in the current population yield highly reliable outcome measures. From a practical perspective, highly reliable tests are able to detect small but significant changes in limited sample sizes and provide meaningful information to coaches and sport scientists regarding changes in physical performance (18
). These findings indicate that the methods employed in the current study would be appropriate to assess the effects of interventions on weightlifting performance in adolescent athletes.
In our investigation, the difference between 1 RM testing trials was 0.8 kg (1.1%) and subjects completed the 1 RM tests with a mean of 3.1 and 3.4 trials, respectively, on day 1 and day 2. In addition, the typical error to be expected between 1 RM power clean trials was 2.9 kg and it appears that a change of at least 8.0 kg is needed to identify real changes in power clean performance over time. The high reproducibility of 1 RM power clean testing and acceptable measurement error in this study was likely due to a number of factors. Our population of adolescents had, on average, 16 months of experience performing a variety of weightlifting movements in a structured strength and conditioning program. Subjects progressed from basic movements (e.g, front squat) to more complex movements (e.g., power clean) as competence and confidence improved. Although training frequency varied throughout the year depending on sport participation and school vacations, most subjects participated in strength and conditioning activities at least twice per week and received constructive feedback on proper form and technique from weightlifting coaches. As previously noted by Kraemer et al (20
), the process of increasing the weight to a true 1 RM can be enhanced by prior familiarization with the testing exercise as well as the expertise of investigators who evaluate the performance of each lift. Of interest, Blazevich and Gill found significantly reduced reliability in an unfamiliar squat strength test in healthy adults who had at least one year of resistance training experience (4
Despite the growing popularity of weightlifting by high school athletes and their coaches in the United States (8
), only limited normative data is available on the power clean exercise for comparison. In the present investigation, subjects lifted ~ 70 kg on the 1 RM power clean whereas the reported 50th
percentile for this lift in 14 to 15 year old high school American football players is 79 kg (17
). Factors including training experience, testing procedures, quality of performance and body mass may have influenced the observed differences in performance. Also, subjects in our investigation participated in a variety of sports including American football, lacrosse, and basketball.
The results of current investigation indicate that 1 RM testing of the power clean exercise can be used to track progress, develop personalized programs and assess the effectiveness of youth strength and conditioning programs. In addition, 1 RM testing can provide motivation during yearly training cycles. However, proper administration of maximal strength and power testing procedures require qualified instruction and consistent feedback on technical movements and desired intensity progression. Although these tests can be used by pediatric researchers and youth strength and conditioning professionals to assess training-induced gains in strength and power, field tests such as the standing long jump or vertical jump may be more appropriate in physical education classes as a general index of muscular fitness in youth.
This study attempted to determine the reliability of the 1 RM power clean in trained adolescent athletes. Our substantive findings are consistent with similar tests measured in adults (21
) and supportive of previous investigations that examined 1 RM strength testing in children (12
). We found that technique-driven 1 RM power clean testing has a high degree of reproducibility in trained adolescents and can be safely evaluated in young athletes provided that standard testing procedures are followed. However, no conclusions can be made regarding the reliability of power clean testing in inexperienced young lifters. Future research might focus on establishing normative 1 RM power clean data for male and female high school athletes for comparative evaluations of maximal muscular power to age- and gender-matched peers.