Resistance training (RT) has been widely used for maintaining or improving the quality of life and sports performance. In this sense, both identification and monitoring of muscle strength levels over time can provide important information for professionals and researchers working in the health area or with sports performance. This information can contribute to the evaluation of the functional capacity and effectiveness of training programs of different natures, favoring the establishment of training overload (31). One of the main reasons for the use of RT is the growing publications of the beneficial effects of training programs aimed at prevention, rehabilitation, health promotion, or improvement in sports performance (1,5,24). However, for these benefits to be achieved, training programs should consider some variables such as frequency, type, duration, and intensity of exercises (1).
It is worth mentioning that although some authors try to justify the use of the term “intensity” through its association with 1 repetition maximum (1RM) percentages (14,40), this term seems to be unable to reconcile effort, load, repetition, genetic influences, and repetition duration (12). According to Fisher and Smith (12), within RT, “intensity” represents only the level of effort applied to a given load. In this sense, 1RM percentages should be adopted only as reference values of the training load. In addition, it should be emphasized that the optimal level of load is exercise dependent, i.e., the percentage ranges ideal for training may vary from 1 exercise to another, although the training objective is the same (37,38). Thus, it is understood that the correct identification of the exercise load magnitude would favor specific muscular adaptations (13).
Considering the strength evaluation, the 1RM test has been used both to estimate the maximum force and to prescribe load percentages in training programs (18,36). For the application of this procedure, the individual performs a specific warm-up in the exercise that the test will be performed, followed by several attempts at full load until failure to correctly perform the movement is observed by the evaluator (35). Usually, the 1RM value is found between 3 and 6 attempts (27,39), with recovery interval between 3 and 5 minutes (23,27). Therefore, for a single exercise, this test requires approximately 30 minutes, compromising or disrupting the training routine of the individual being tested (39). Therefore, the test is barely used in gyms, clubs, and fitness centers due to its difficulty of operationalization because it depends on great human resource and high demand in terms of time (19). In addition, it needs to be repeated for each of the exercises that make up the training program.
Alternatively, another strategy used to prescribe the training load is the use of maximum repetition zones for a given load (1). However, Hoeger et al. (18) observed that, regardless of training status or sex, for the same relative load, there was a difference in the maximum number of repetitions performed in the different muscle groups tested. Their results showed mean variations between 12 and 22 repetitions in the leg press at 80% of 1RM, for example. To solve this problem, some studies have investigated the exercise “intensity” through load self-selected by muscle grouping (11,16,29) because the adherence of individuals to training programs was a positive factor found in studies of this category (10). The best way to quantify 1RM without requiring the application of the test itself seems to be by determining 1RM predictive equations (21,25).
To respond to this need, some authors have conducted studies based on anthropometric variables (30,32), maximum number of repetitions performed with 1RM percentages (19), and maximum number of repetitions in exercises with fixed loads (7,39). In this sense, for a better professional follow-up about the prescription of training programs, the use of the ideal load must be correct and precise according to the goal of the individual to be trained.
It is important to emphasize that the scientific literature presents a very broad body of evidence about load quantification in RT exercises. This broad methodological scope, in addition to evidencing the lack of a standard protocol for the verification of an individual's muscular strength levels, has served as the basis for studies that evaluate, for example, the effects of stretching on strength performance (3,20) and strength exercises on cardiovascular responses (5,15). However, for the results obtained in studies of this nature to unequivocally represent the trends and magnitudes of the expected responses in professional practice, it is important to recognize whether in the daily life of gyms, clubs, and fitness centers, training occurs based on maximal repetitions, as it is in studies. If the training load used in studies is different from that used in the daily training, its results should be analyzed with caution because the effects identified in experiments may be overestimating their responses.
Considering the methodological difficulties mentioned above for assessing the maximum load for each exercise, although it was possible at first to apply tests for the initial training prescription, it is unlikely that these procedures will be repeated throughout the program. This is even more evident in gyms and clubs due to the high number of people exercising simultaneously. In this way, it could be inferred that load increases made throughout the training progression are subjectively determined and possibly self-selected, taking as reference the number of repetitions to be performed. It is not clear, however, whether this self-selected load matches the maximum number of repetitions proposed for each exercise, and if, as a result, subjects are underachieving training goals due to an underestimated training load.
In this sense, the aim of this study was to identify the number of maximum repetitions that strength training practitioners can perform with the load commonly used (self-selected) to perform 10 repetitions in their training routines. The exercise chosen was bench press because it is one of the most popular exercises used for upper limb strength training, especially involving chest, shoulders, and arms (22). In addition, most studies in scientific literature use it as a tested exercise, providing reference values for the training load (18,19,26,32).
Experimental Approach to the Problem
A cross-sectional design was used to test the hypothesis that RT practitioners use to perform 10 repetitions on free-weight bench press exercise with loads much lower than that equivalent to 10RM. In a single visit, an RT group composed of experienced male young adults underwent standardized warm-up exercise followed by a single bout of maximum repetitions on free-weight bench press using self-selected 10 repetitions load (S10RL). Before beginning the procedure, participants answered questions about age, body mass, height, goal of strength training, order of execution of the bench press exercise in the daily training program, and S10RL. Maximal repetitions with self-selected load (RMS10RL) were analyzed according to participants' goal of strength training because individuals who aim at muscle hypertrophy are supposed to train with higher loads when compared with other goals. Likewise, the study analyzed RMS10RL among individuals who adopted higher loads vs. those who adopted lower ones. All participants received instructions not to perform exercises before experimental procedures. Data collection took place between July and October (∼4 months length).
One hundred sixty healthy trained men ranging between 18 to 35 years. (± SD age 25.7 ± 4.5 years, body mass: 81.2 ± 10.4 kg, height: 177.9 ± 6.2 cm) volunteered to participate in this study. All participants had minimum of 6 months RT experience and have used free-weight bench press in their training routines. Inclusion criteria were (a) individuals who have performed RT for at least 6 months with minimum frequency of 3 sessions per week; (b) those who could perform full range of the free-weight bench press exercise; (c) those who did not perform any other exercise or physical activity before the study procedures; and (d) those who did not present any medical conditions that could confound experimental procedures. All participants received information of the study procedures, as well as risks and benefits, and signed a written informed consent form in according to the Declaration of Helsinki. The experimental procedures were approved by Federal University of Sergipe Ethics Committee.
To minimize measurement error, the following strategies were adopted: (a) standard instructions concerning the experimental procedure were given to participants before the test; (b) participants received standardized instructions on exercise technique (6); (c) body position was held constant; and (d) verbal encouragement was provided during the free-weight bench press to elicit maximum effort from each participant.
The procedure consisted of performing a single bout of free-weight bench press. At first, the following question was performed: “What weight do you usually lift for 10 repetitions on free-weight bench press exercise?” The answer was considered the S10RL. After the answer, the individual performed a specific warm-up with the same free-weight bar and bench, which consisted of a 10-repetition bout with 50% of S10RL and 1 minute later, a second 5-repetition bout with 70% of S10RL (35). After a 2-minute recovery interval, the individual was instructed to perform as many repetitions as possible at S10RL (Figure 1). One repetition was considered if the subject lowers the bar to touch his chest, and then press it upward by fully extending his forearms. Barbell velocity was not controlled to simulate daily strength practice routines. All procedures were monitored by a single and experienced examiner.
All sample characteristic variables presented normal distribution (Shapiro-Wilk test, p > 0.05). The RMS10RL was analyzed with the single sample t test, adopting the reference value of 10 repetitions. Data were also analyzed by splitting the sample into 2 groups according to RT personal goals and absolute load lifted. Resistance training personal goals were defined as hypertrophy vs. other objectives (health promotion, weight loss, etc). The sample was stratified according to the median load lifted, as groups below median (BM) and above median (AM). These groups were also compared in terms of relative training load. Student's t test for independent samples was used for all comparisons between groups.
Data were descriptively analyzed to determine RMS10RL ranges and free-weight bench press execution rank order during training. To estimate the load corresponding to 1RM, we first used the equation proposed by Guedes and Guedes (17), based on statistical regression models that suggest that the 1RM load decreases at about 2–2.5% for each repetition. Therefore, the equation used was as follows: 1RM = submaximal load/(100%−[2% × reps]). Subsequently, we adopted the simple rule of 3 to determine the relative loads for 1RM and 10RM. Statistical analyses were performed using SPSS software statistical package version 20.0 (SPSS, Inc., Chicago, IL, USA), and statistical significance was set at p ≤ 0.05.
Individuals performed 16 ± 5RMS10RL (median = 15; confidence interval [CI] 95% = 15.6–17.3 reps), which represent a statistical difference for the 10-repetition reference value (p < 0.001). The most prevalent RMS10RL range was from 13 to 15 repetitions, representing a relative load between 67 and 77% (Table 1). The average relative load for 1RM and 10RM was 67 ± 10% and 65 ± 16%, respectively.
Table 1. -
Distribution of the sample to RMS10RL
, percentage of ranges of RMS10RL
, and relative intensities of the 1RM and 10RM.*
||% Range of RMS10RL (%)
||Relative intensities of the 10RM (%)
||Relative intensities of the 1RM (%)
*RMS10RL = maximum repetitions on free-weight bench press using self-selected 10 repetitions load.
Most individuals (76%; n = 122) aimed at hypertrophy as personal RT goals, whereas 24% (n = 38) reported other targets. There is no difference according to RT personal goals (16 ± 5 vs. 17 ± 6RMS10RL, for hypertrophy and other objectives; CI 95% = −2.8 to 1.0; p = 0.338, Figure 2).
The median load lifted was 54 kg. The BM group (load ≤54 kg) represented 51% of the sample. The BM group performed more maximum repetitions compared with AM (CI 95% = 2.8–5.7; p < 0.001; Figure 3).
In terms of relative load, there was a significant difference between groups, as the AM group trained at higher loads both on the load for 1RM as for 10RM (Figure 4). Ultimately, about 82% of participants reported that free-weight bench press is the first exercise for the chest muscle group in their daily training routine.
The aim of this study was to identify the number of maximal repetitions that RT practitioners can perform with the load commonly used for 10 repetitions in their training routines in the free-weight bench press exercise. The main finding of this study was that RT practitioners do not usually train with maximum loads. Most individuals can perform a number of repetitions well above the 10 repetitions expected for the self-selected load. They usually finish the exercise in the number fixed by coaches, not reaching maximum voluntary muscular actions (maximum repetitions).
Fleck and Kraemer (13) reported that the performance of maximal voluntary muscular actions in RT is described by muscle overload and that the level of muscular requirement must be increased in order for physiological changes to occur (hypertrophy and/or strength gains). The concept of maximal voluntary muscular actions seems to be overlooked in RT routines, given the high number of repetitions performed by participants in this study. During procedure, the individuals in our sample achieved maximal voluntary muscle actions because they were stimulated to achieve them, unlike what seems to occur in the daily life of gyms.
Our results suggest that individuals do not actually train at their limit of maximal repetitions. In fact, almost half of the sample (about 47%) trained with load equivalent to less than 67% of 1RM. Nonetheless, it is noteworthy that the use of 1RM percentages to determine the training load has long been disputed. In this sense, Hoeger et al. (18) performed 1RM tests in 7 exercises on untrained and trained men and women. They then established loading percentages (40, 60, and 80%) for 1RM and asked participants to perform the maximum number of repetitions. There was a wide variability in the number of maximal repetitions, regardless of exercise, training status, or sex. Men trained in 80% bench press exercise performed an average of 12RM. Despite emphasizing the limitations of prescription based on 1RM percentages, the authors suggest using load equivalent to or greater than 80% of 1RM for large muscle groups for the execution of 10RM. In our study, only 1 of 5 subjects appeared to be training with loads above this recommendation (10–12RM).
In the following 2 decades, strength trained men undergoing a similar training protocol performed 9RM with 80% of 1RM (n = 8) (36), and 8–9RM with 85% of 1RM (n = 9) (2) in the bench press exercise, showed results conflicting to the study of Hoeger et al. (18). In these studies, individuals were unable to reach 10RM with loads equal or higher than 80% of 1RM. All this information, associated with the results of this study, ratifies the argument that the training loads observed in scientific literature do not represent the natural conditions of daily practice, which is based on self-selected loads.
Another point observed in this study refers to the participants' RT goal. When questioned, 3 of 4 individuals answered that hypertrophy was the main goal when performing RT. Surprisingly, there was no difference in RMS10RL for each reported objective (hypertrophy vs. others). The expectation was that workouts aimed at hypertrophy should use loads closer to the expected 10 repetitions, which in fact did not occur.
In this sense, Campos et al. (4) found greater muscular hypertrophy in groups that trained 3–5RM and 9–11RM in the leg press, squatting, and leg extension. In our sample, individuals performed a much higher number of repetitions. In fact, although the majority aimed at hypertrophy, almost half of our sample adopted loads that fit local muscular endurance training (above 15 repetitions) (1). However, although a little more than half of the sample complied with ACSM recommendations for muscle hypertrophy gains (≥70% of 1RM) (1), only 1 of 5 individuals trained in the optimum load zone suggested by Campos et al. (4) (up to 11RM). In addition, only 4.4% (7 individuals) achieved the recommendations of Fry (14) for training load (80–95% of 1RM).
Some authors present metabolic stress as one of the factors for muscular hypertrophy (9,28,34). Hereupon, Schoenfeld (33) published a very careful literature review regarding metabolic stress and observed that it is possible to obtain muscular hypertrophy with lower loads. However, most studies advise individuals to train up to maximal voluntary fatigue (28,34). Nevertheless, it is noteworthy that in our study, individuals who sought hypertrophy, although being able to perform an average of RMS10RL, in their daily routine, would have stopped exercising shortly after the tenth repetition. Thus, although Da Silva-Grigoletto et al. (8) suggest that the use of repetitions up to movement failure is usually applied in sports training, our results show that individuals did not reach this point and, possibly, did not generate metabolic stress enough to optimize muscular hypertrophy (33).
As expected, participants who lifted more weight (AM group) performed fewer repetitions than the BM group (14 ± 6 and 19 ± 3RMS10RL, respectively). Considering that an absolute load may represent different effort levels among individuals, the comparison of relative loads for the same groups was timely. Thus, it was observed that the AM group trained with relatively higher loads compared with the BM group, although the loads still remained below the ACSM recommendations (1) for hypertrophy. However, none of the groups approached the optimal zone of maximal repetitions for hypertrophy training proposed by Fry (14).
A possible limitation of this study is the fact that we did not reassess RMS10RL performed by participants, submitting them to another evaluation day (retest). However, we believe that the large sample size may have attenuated possible intraindividual variations. The choice of bench press exercise for these analyses proved to be correct because 4 of 5 individuals performed it as the first exercise of the training session. To our knowledge, there are studies investigating the order of execution of this exercise in training routines. Thus, the ecological validity of the study was maintained, as in the daily routine, subjects would not perform other exercises before bench press, excluding variable previous fatigue in the transfer of information from the laboratory to the practical application.
It was concluded that most individuals can perform a number of repetitions well above the 10 repetitions predicted for the selected load. Therefore, the training routines are not compatible with maximum effort or with their most prevalent goal, muscle hypertrophy.
For researchers, the present data elucidate that loads applied on studies based on 1RM percentage loads may be overestimating the effects related to resistance exercises, such as stretching or cardiovascular responses, for instance. Therefore, the interpretation of published data must consider this scenario, ensuring a proper decision-making process.
Based on the present results, it seems beyond a shadow of doubt that training loads have been receiving poor attention, thus, coaches and trainers must address this issue more carefully to allow a more objective and reliable exercise prescription and control. Because subjects do not use maximum load or repetitions on daily basis, coaches and trainers should be aware of situation and adjust training loads to match evidence-based recommendations (14) to enhance training results. When prescribing RT programs, especially if the goal is hypertrophy, trainers must make sure that subjects fulfill maximum repetitions, with loads compatible to this level of effort and objectives.
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