Muscular strength is an important component of physical fitness, either to perform everyday activities, or to improve the performance in many sports. Although there are many methods to assess muscular strength, the 1-repetition maximum test (1-RM) is among the most common, probably because it can be used to assess strength of almost any muscle group, it is relatively easy and inexpensive to perform, and it reflects maximal strength.
The accurate determination of muscular strength is important, especially in assessing strength gains associated with resistance training (1,11,13). Many studies have suggested that for an accurate assessment of 1-RM load, the lifting technique, which typically involves familiarization, must be well known (4,6,12,20). Moreover, gender, age, physical activity level, body composition, characteristics of contraction, initial position, and stabilization (12) should also be considered.
Ploutz-Snyder and Giams (19) were the first ones to show changes in muscular strength during 1-RM familiarization sessions in young and aged women. It was also observed in prepubescent boys (10), untrained middle-aged (14) and older individuals (21), and male athletes (7). These studies confirmed the necessity of familiarization in 1-RM tests in subjects without previous experience in resistance training. However, there are no studies analyzing the influence of familiarization on individuals with experience in resistance training.
In addition, the number of familiarization sessions to accurate assessment of 1-RM differs among studies. It has been suggested that factors such as age, exercises tested, and physical activity levels might influence the number of sessions necessary for familiarization. However, once the studies used different statistical analysis to determine the number of sessions for familiarization, it might have resulted in different familiarization indexes (7,8,10,14,17,21,24,25). Thus, the objectives of the present study were (a) to verify the familiarization process during 5 sessions of 1-RM tests in women with previous experience with resistance training programs but detrained for 6 months, and (b) to evaluate the familiarization using different statistical analysis. We hypothesize that women with previous experience in resistance training will increase 1-RM load between familiarization sessions. Moreover, the statistical analysis used will have influence in the familiarization results.
Experimental Approach to the Problem
To analyze the familiarization, we applied 5 sessions of 1-RM tests in women with previous experience in resistance training but detrained for 6 months. We analyzed the results using ANOVA for repeated measures, intraclass correlation coefficient (ICC), Bland-Altman plotting, and the session in which subjects reached the highest 1-RM load during the 5 familiarization sessions.
The study was composed of 27 healthy adult women, with ages ranging from 18 to 30 years (21.6 ± 2.5 years; 59.1 ± 6.7 kg; 1.65 ± 0.04 m; 21.8 ± 2.4 kg/m2), all sedentary or moderately active (regular physical activity less than twice a week during the 6 months before the study). All subjects had more than 6 months of experience in resistance training but had not performed resistance training 6 months before the study. The research was approved by the institutional research ethics committee and all subjects provided informed written consent.
Maximal dynamic strength was evaluated using the 1-RM test in the bench press, squat in Smith machine, and arm curl exercises, in this order. The rest period between the exercises ranged from 3 to 5 minutes. We applied 5 sessions of 1-RM tests in distinct days. The 1-RM load in each familiarization session (1-RM load), the highest load between the 5 sessions, and the session in which the highest load was obtained were used for analysis.
The test in each exercise was preceded by a warm-up set (6-10 repetitions), with approximately 50% of the estimated load used in the first attempt of the 1-RM test. The testing procedure was initiated 2 minutes after warm-up. The subjects were oriented to try to accomplish 2 repetitions with the imposed load in 3 attempts in all exercises. If 1-RM load was not reached in 3 attempts in any of the exercises, the session was discarded and the subject was excluded from the study. Therefore, the 1-RM load was the one in which the subject was able to complete 1 single maximal execution (6). Execution technique and form of each exercise were standardized and continuously monitored to guarantee reliability in the maximum strength assessment in the 5 sessions, separated by 48 to 72 hours. All the sessions were supervised by 3 experienced researchers for greater safety and integrity of the subjects during the tests (6).
The data were presented in mean ± standard deviation, and statistical analyses were processed in the SPSS 13.0 version software. The sphericity was assessed using the Mauchly's test. The ANOVA for repeated measures was used to compare the 1-RM familiarization between sessions. When F was significant, the Bonferroni post hoc test was applied to identify the differences (p < 0.05); to complement analysis, the effect size (η2) was presented. The ICC was used to analyze the correlation between all the sessions. Bland-Altman plotting procedures (2) were used to determine relative absolute limits (%LoA) and absolute limits (LoA) of agreement between sessions.
The number of subjects that reached the highest 1-RM load in each of the 5 familiarization sessions is shown in Table 1. In the 3 exercises, only 14.8% of the subjects obtained the highest 1-RM load in the first familiarization session. The greatest proportion of subjects obtained the highest 1-RM load between sessions 4 and 5.
The ICC and ANOVA results are shown in Table 2. All exercises presented good ICC between the familiarization sessions (0.97-0.98). ANOVA results showed that the 1-RM load stabilized (reached a plateau) in sessions 3 or 4 in the bench press and arm curl and in sessions 2 or 3 in the squat. There were significant increases in 1-RM load from the first to fifth familiarization sessions in the bench press (+5.7%, F = 10.2; p < 0.01; η2 = 0.28), squat (+5.4%, F = 4.5; p < 0.01; η2 = 0.15), and arm curl (+11.1%, F = 18.6; p < 0.01; η2 = 0.42).
Individual points of 1-RM load in the 5 sessions in the bench press, squat, and arm curl are shown in Figures 1, 2, and 3, respectively. In the 3 exercises, the pattern of responses of 1-RM load in 5 familiarization sessions was different among subjects.
In Table 3, the Bland and Altman (2) plotting parameters are listed in the bench press, squat, and arm curl. The analyses were established using the mean of 1-RM load between the compared sessions (x axis) with the differences (bias) between the compared sessions (y axis). The bias (kg) and the limits of agreement (being ± 1.96 standard deviation of 95% of confidence interval) of the differences are presented in kilograms and in percentage (LoA and %LoA), respectively. These analyses were also done in Figure 4.
The limits of agreement and the bias between paired comparisons achieved progressively better agreement in the squat and arm curl. However, in the bench press, even with the LoA being better in sessions 3 to 4, in comparison with other sessions, the bias was worse than in sessions 1 to 3 and 1 to 2. In addition, the Bland and Altman plotting (2), used in the squat, reached better agreement indexes in sessions 2 to 3 than in sessions 3 to 4, determining lower agreement values (bias = −1.5 and LoA = 18.7 kg). Nevertheless, in sessions 4 to 5, the bias (−0.1, 0.1, and −0.2 kg) and LoA were (6.3, 5.0, and 14.8) in the bench press, squat, and arm curl, respectively. Thus, sessions 4 to 5 presented better agreement in paired comparison.
Figure 4 shows the limits of agreement by Bland-Altman plotting between sessions 1 and 5 and between the sessions in which the majority of subjects reached the highest 1-RM load. The best agreement was observed in session 4 when compared with the highest 1-RM load in the bench press (%LoA = 18.4), squat (%LoA = 15.6), and arm curl (%LoA = 15.8) (Table 3).
The objective of this study was to analyze the familiarization to 1-RM tests in women with previous experience in resistance training. The results showed significant increases in 1-RM load among the 5 familiarization sessions in the bench press (+5.7%), squat (+5.4%), and arm curl (+11.1%).
These data confirm the importance of familiarization to the 1-RM test, even in women with previous experience in resistance training. Thus, part of the strength increase that has been attributed to the training program could result from lack of previous familiarization in the 1-RM test. This may cause a false interpretation on the adaptations in resistance training programs on strength. These results suggest that familiarization might be taken into account when planning resistance training.
Our results are in agreement with others, demonstrating that familiarization sessions are required for accurate assessment of strength (7,8,10,17,19,21,24,25). It shows the need of 3 to 4 1-RM familiarization sessions even in subjects with previous experience in resistance training. Other studies have shown differences in the number of familiarization sessions in subjects without experience in resistance training (10,19). For example, 3 to 5 familiarization sessions were needed in 10-year-old boys (10), 6 to 7 sessions were needed in elderly women (19), 2 to 3 sessions were needed in well-conditioned male subjects (7), and 2 sessions were needed in untrained middle-aged subjects (14). These differences might be because of the subject's age, previous experience in resistance training, exercises analyzed, and statistical analysis used.
Thus, one of the objectives of the present study was to compare different statistical analyses in the determination of familiarization to 1-RM test. Previous studies have used 4 statistical analyses to determine the familiarization to 1-RM test: (a) ICC, which indicates the correlation between the sessions tested; (b) highest 1-RM load, which takes into account the session in which subjects obtained the highest 1-RM load between the sessions used; (c) ANOVA, which has been used to compare 1-RM load among the familiarization sessions and to identify a plateau, and (d) Bland-Altman plotting, which might provide a more detailed report of the responses of 1-RM load among familiarization sessions, showing the agreement between sessions.
The reliability coefficients, such as Pearson “r” or ICC, have been widely used in studies analyzing the reliability of 1-RM test (15,18). These are useful for showing reliability, but they are not well suited to determine differences in means between sessions and to identify a plateau or stabilization point. For example, some authors report moderate to high levels of reliability based on the ICC in the 1-RM test (3,20). However, these results must be carefully analyzed because the present study showed high ICC (bench press ICC = 0.98; squat ICC = 0.98; arm curl ICC = 0.97), whereas ANOVA identified significant differences in 1-RM load between familiarization sessions. In addition, ANOVA showed that stabilization in the bench press and arm curl occurred in the majority of subjects in sessions 3 or 4, whereas in the squat it occurred in sessions 2 or 3.
Using the same procedure applied by Ploutz-Snyder and Giams (19), the results of our study showed that the highest 1-RM load was obtained after 3.6 sessions in the bench press, 3.3 in the squat, and 3.1 in the arm curl. The results are similar when analyzed by ANOVA in the bench press and arm curl (3 to 4 sessions) but different in the squat (2 to 3 sessions). Nevertheless, the results of ANOVA and highest 1-RM load were different from the results obtained with the Bland-Altman plotting, which showed better agreement between sessions 4 or 5. This confirms the hypothesis that the number of familiarization sessions to 1-RM tests depends on the statistical analysis used. Thus, divergences in familiarization sessions in previous studies might also result from the statistical analysis used (7,8,10,14,17,19,21,23-25).
The increase in 1-RM strength during familiarization sessions may be a result of many factors, such as learning execution technique, increased capacity to tolerate maximal loads, increased motor unit recruitment, and decreased coactivation of antagonist muscles (5). Moreover, in the first weeks of the resistance training the increase strength has been attributed to neural adaptations (9,16,22). However, this could suggest that the increase in strength between familiarization sessions is a result of the intervals used, which could favor a training effect between the familiarization sessions. We do not believe in this hypothesis because a previous study observed an increase in strength between familiarization sessions using longer intervals. Cronin and Henderson (7) found a strength increase after 1-RM tests using 7 days of interval between sessions, showing that other factors rather than the training effect might cause a strength increase between familiarization sessions.
This study indicates that the familiarization sessions of 1-RM tests in the bench press, squat, and arm curl are important even in individuals with previous experience in resistance training. In addition, the results show that Bland-Altman plotting indicates a larger number of familiarization sessions than ANOVA and highest 1-RM load, suggesting that the statistical analyses used for the determination of familiarization might influence the results.
The familiarization sessions are important for an accurate assessment of 1-RM load. In addition, the statistical analyses used have an influence on required sessions for familiarization to 1-RM test. Therefore, overall, we suggested 3 to 4 familiarization sessions to an accurate assessment of 1-RM load in the bench press, squat, and arm curl. This recommendation should be followed, especially in research involving strength changes among training programs. However, when the accurate assessment of 1-RM is not relevant or not possible, as in sports or resistance training programs in gyms, it is important to consider that the 1-RM load will be underestimated.
The authors would like to acknowledge Capes and IC-UEL for the scholarships, and to thank the women who participated as subjects in our study and also Fábio Yuzo Nakamura, Patricia Chimin, Rubem Cauduro, Pedro Bevilaqua Alves, and Fernanda Goulart Ritti Dias for their helpful comments during the preparation of this manuscript.
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Keywords:© 2009 National Strength and Conditioning Association
familiarization; muscular strength; 1-RM tests; resistance training; women