Resistance exercise is widely recommended for achieving distinct objectives such as increased muscular strength, power, endurance and hypertrophy. 1,2 To place emphasis on each specific objective, coaches and practitioners manipulate training variables such as load intensity, volume, and rest periods between sets in an adequate dose/response manner. Those training for maximal muscle strength, should regularly apply the gold standard method for strength evaluation such as the one maximum repetition (1-RM) test as suggested by the American College of Sports and Medicine (ACSM) in order to assess training progress. 1

For nearly six decades, the 1-RM method has been the main alternative for assessing maximum strength and has been largely implemented for the majority of experiments that evaluate strength. 3–7 In addition, in its latest position stand on resistance training, the ACSM recommended for strength, power and hypertrophy goals, that trained subjects should train in a repetition range of 1–12 repetitions applied in a periodized scheme. 2 Specifically, those who are aiming to improve dynamic strength should consider training with loads ranging from one to six maximal repetitions. 2 However, while a great number of experiments analyzed rest period manipulation and repetition performance in distinct repetition zones, 8–12 very few experiments have focused on identifying the optimal rest period length between 1-RM attempts.

Specifically, only two studies have compared the direct influence of several rest period lengths 1-RM attempts. Weir et al. 6 and Matuszak et al. 7 observed that a 60-s rest period was sufficient for subjects to successfully complete two consecutive 1-RM sets in barbell bench press and back squat exercises, respectively. However, neither of these studies analyzed rest period lengths shorter than 60-s between consecutive 1-RM attempts, thus creating a persistent gap in the body of literature.

It is well established that when shorter the rest duration between sets, greater the acute response of blood markers (such as blood lactate) and increased perceived fatigue. However, this kind of scenario does not necessarily translate to an acute decrease on exercise performance as previously demonstrated. 11 Additionally, Scudese et al. 13 observed significant increases on perceived effort when a short rest period between sets was implemented, even when training volume was maintained with near-maximum repetitions. Therefore, understanding the ideal duration for planning the rest period, goes far deeper then training efficiency alone (time vs. training volume), actually, it has the potential to enhance the training intensity.

Furthermore, the rating of perceived exertion (RPE) has been used for assessing the subjective intensity of resistance exercise sets 14 and could improve the overall understanding of fatigue outcomes. Previous studies 8–12 reported that shorter rest period lengths (i.e. 1-min) increased RPE over the course of multiple sets when utilizing 3-RM to 10-RM loads. Nevertheless, the RPE method was not applied in the Weir et al. 6 and Matuszak et al. 7 studies, thus, precluding further data interpretation. Presently, no study has investigated consecutive set performance and RPE with rest periods shorter than 60 s when utilizing an absolute 1-RM load. Therefore, the purpose of this investigation was to compare different rest period lengths between consecutive 1-RM bench press attempts on performance and RPE in resistance-trained men.

From the data obtained from Cochran Q analysis, there was no significant difference in the ability to successfully perform a second 1-RM with 20, 40, or 60-s rest between attempts (p = 0.882). Specifically, no significant differences were found in the successful completion of the first and second attempts for the 20-s (p = 0.317), 40 s (p = 0.083), and 60-s (p = 0.157) trials, respectively. For the 20 and 60-s rest conditions Δ% = 88.88% of subjects completed the second attempt. As for the 40-s protocol, only 83.33% of subjects completed the second attempt (Fig. 2).

Fig. 2.

(0.08MB).

Number of success and unsuccess for the second maximal repetition attempt.

For the RPE data, prior to the second attempt, significantly higher values were observed for the 20 s versus the 60-s trial (p = 0.04). There were no significant differences in the RPE (prior to the second attempt) for the 20 s versus the 40 s (p = 0.54), or the 40 s versus the 60-s rest conditions (p = 0.83). For the post-set RPE, significantly higher values were observed for the 20-s trial when comparing scores following the second attempt versus following the first attempt (p = 0.01). Conversely, no significant differences were observed between attempts in the post-set RPE for the 40-s (p = 0.12) and 60-s rest conditions (p = 0.48). Additionally, following the second attempt, the post-set RPE was significantly higher for the 20-s versus to the 40-s (p = 0.008) and 60-s (p = 0.023) trials, respectively. For clarity, all the results are presented in Table 1 by the median (25%–75%).

The key finding of this study was that regardless of the rest period (i.e. 20, 40 or 60-s rest between 1-RM bench press attempts), subjects were, for the most part, able to complete the second attempt. Nevertheless, the 20-s trial resulted in higher RPE values versus the 40 s and 60-s trials. To the authors’ knowledge, this was the first study that investigated acute performance and subjective responses arising from 60 s or less rest between 1-RM attempts.

Throughout the results analysis, it became evident that for both maximum muscle strength testing and 1-RM load zone training, the recommendation for longer rest periods does not appear to be supported. 1,2 Unexpectedly, the shortest rest period (i.e. 20 s) was as effective as the other rest periods (i.e. 40 s and 60 s) in performing two consecutive successful attempts with 1-RM loads in the bench press exercise. Therefore, prescription of rest periods longer than 60 s between maximal attempts will unnecessarily increase the total time of a testing or workout session, without providing additional benefits for recovery. However, it should be noted that progressively longer rest intervals between maximal attempts might be necessary for elite lifters or during workout scenarios when more than two consecutive sets are performed in the 1-RM loading zone. 9

Previous studies compared different rest period lengths between two consecutive 1-RM attempts. 6,7 Specifically, Weir et al. 6 demonstrated that subjects were able to successfully perform a second maximal bench press attempt with a 1-min rest period following the first attempt. Furthermore, the authors did not find any performance differences when comparing 1, 2, 3, 5 or 10 min between consecutive maximal attempts. Similarly, Matuszak et al. 7 reported no statistical difference in the ability to successfully perform a second maximal back squat attempt with one, three or five minute rest periods following the first attempt. The present investigation differed from these studies in comparing rest periods shorter than 60 s between maximal bench press attempts. Our results showed that for the most part, a 20-s rest was sufficient to allow for a successful repeated attempt.

However, for distinct loading zones, the results appear to be quite different. For instance, Scudese et al. 8 analyzed the effects of distinct rest period lengths with near maximal loads (3-RM) on BP performance and RPE values. Sixteen trained men performed four BP workouts with 1, 2, 3, or 5 min rest periods between five consecutive sets. Scudese et al. 8 found increased total BP repetitions completed with 2, 3 and 5 min rest between sets versus 1 min rest between sets. Performance reductions (relative to the first set) were observed starting as early as the second for the 1 min condition and only at the fifth set for all of the other rest conditions (i.e. 2, 3 and 5 min). The current study (1-RM) shares resemblance with Scudese et al. 8 due to the high intensity load range implemented (3-RM) within the optimal loading zone for maximal strength gains as recommended by the ACSM. 2

Although, when decreasing the load and consecutively increasing the number of repetitions (i.e. 10-RM) Senna et al. 10 observed very distinct results for different types of exercises (multi and single-joint for upper and lower body). For instance, the results indicated that for the upper-body multi-joint BP exercise, the total number of repetitions performed was greater with 3 and 5 min compared to the shorter 1 min rest period. For the other exercises (i.e., leg press, leg extension, and machine chest fly), significant differences were evident between all rest conditions (1 < 3 < 5-min rest). For all exercises, consistent declines in repetition performance (relative to the first set) were observed for all rest conditions, starting as early as the second set for the 1 min condition and by the third set for the 3 and 5 min conditions. These data are on par with the majority of the scientific literature regarding the acute manipulation of the rest period variable, indicated that shorter rest periods triggered predictable reductions in repetition performance and force production over consecutive sets within loading zones ranging from 3-RM to 10-RM. 9,10 However, with a maximal effort attempt (1-RM), the scenario may change, and trained individuals might be able to successfully perform at least a subsequent maximal attempt for the bench press, even with only 20-s rest following the initial attempt.

The RPE values were implemented in order to assess the subjective intensity from resistance exercise. 14 Prior studies 8,10 reported that the RPE values, generally increases over the course of consecutive sets when comparing one minute versus three or five minute of rest with 10-RM loads. More recently, Scudese et al. 8 verified higher pre-set RPE scores with 1 and 2 min of rest between sets with 3-RM loads for the BP. The post-set RPE were also higher for short compared to long rest lengths between sets. 8 For current study, the pre-set RPE values were significantly higher for both the 20 and 40 s versus the 60-s rest period for the BP exercise. Significant increases were also evident for the post-set RPE for the 20-s rest condition compared with longer rest periods (40 and 60 s). The overall RPE (pre and post-set) outcome indicates an augmented fatigue rate perceived for the shorter 20-s rest condition versus other rest conditions, although this tendency was not reflected in the 1-RM performance for any rest conditions analyzed.

Senna et al. 11 observed that when applying a shorter recovery time between sets, higher blood lactate and RPE values were found. However, these results were not followed by a decrease on exercise performance. This outcome is very similar with those found on the present investigation. In fact, this might have occurred by the strength characteristics of the protocol (1-RM), that although maximum, the fatigue was promptly surpassed even by the shorter rest period design (20 s). In addition, Scudese et al. 13 found elevated RPE scores when comparing short with longer rest periods even with a previously fixed training volume. This result brings to light that is possible to increase intensity when manipulating rest period alone, without actuating directly on exercise volume.

When analyzing our rest period design (with very short duration such as 20, 40 and 60 s) we can estimate that anaerobic glycolysis might be largely upregulated in order to compensate for the any possible incomplete resynthesis of the phosphocreatine pathway. One of the key factor that might triggered the elevated RPE values from shorter rest protocols is that a greater reliance on anaerobic glycolysis is usually associated with the accumulation of H+ that lowers the pH of intracellular fluid resulting on afferent feedback from muscle chemoreceptors and nociceptors. The central nervous system responds to the increase in RPE by increasing pulmonary ventilation and motor unit recruitment in order to deal with these metabolic changes. 14

Based on both the guidelines from the ACSM 2 and the new data found from this experiment, athletes and advanced individuals aiming for maximizing strength should benefit from consecutive maximal strength attempts (1-RM) and apply this kind of method as part of a periodized routine. Moreover, it has been demonstrated that at least for the second attempt, practitioners can apply very short rest periods, like 60, 40 or even 20 s with no acute decrease on performance. However, is important to highlight that traditionally, 1-RM bouts are implemented for load testing purposes. These findings could amplify the tools for coaches, who are intending to increase training intensity or even load testing time-efficiency.

These results are applicable and limited to the specific exercise, rest conditions, intensity, volume and sample tested. Therefore, while accounting for the aforementioned limitations, coaches can interpret and apply the information by prescribing distinct rest periods for workouts with strength specific load zones (1-RM) or even maintain the efficiency of 1-RM test trials. However, we strongly recommend future experiments that should evaluate distinct exercise schemes, in different limbs and whole-body training sessions with multiple sets.

The authors have no conflicts of interest to declare.