Resistance training (RT) has been widely recommended as an effective strategy for improving muscular fitness. It is already well established that a well-designed RT program might promote progressive increases in strength, power and muscular endurance of regular practitioners. 1,2 Several investigations have shown that manipulations of different methodological variables like the rest periods between sets, will trigger different responses in neuromuscular, metabolic and hormonal system. 1,3–5 Recently, a great number of experiments have investigated the direct relationship of rest period between sets and repetitions performance. 6–11

However, although recent studies on the effects of the rest interval between sets provide new tools for RT prescription, there is little evidence related to distinct rest methods, for example, the implementation of active (AR) or passive recovery (PR) between sets. 6,12 Specifically, Hannie et al. 12 analyzed the influences of different recoveries between sets on the bench press exercise performed with 65% of a maximum repetition (RM) (15-RM) to failure in 15 untrained individuals. The AR was performed on an ergometer cycle at 45% of the peak of maximum oxygen consumption (VO2max) for time fractions within 2 min of total rest. In contrast, the PR consisted of the entire amount of rest (2 min) consisting of a static recovery. Their results suggest that the AR promoted better recovery found on repetition performance during multiple sets progression when compared to RP.

After extensive research, we did not find any investigation that focused on the influences on repetition performance in multiple sets comparing PR and AR performed on a treadmill (ART) for resistance-trained individuals. Additionally, there are other known influences of different types of recovery for perception of exertion (RPE). These data can contribute to future prescription on distinct methods involving recovery between sets in order to optimize the time-efficiency and training performance. Therefore, the aim of this study was to compare different recovery methods on repetitions performance and perceived exertion. It was hypothesized that there would not be a detrimental effect of active recovery protocol on performance, in part by optimizing blood lactate removal and thus, decreasing H+ ions content that might reduce muscle acidosis.

Excellent reproducibility in 10-RM loads in the test and retest was observed (r = 0.97; p < 0.0001). In addition, the paired Student T test did not show any significant difference between the 10-RM load tests (p = 0.582).

For the total number of repetitions completed in bench press exercise, no significant difference (p = 0.181) were observed between PR (25.50 ± 3.13 repetitions) and ART (26.07 ± 2.46 repetitions) as shown in Figure 1. In addition, the AUC did not show any significant differences between PR (47.05 ± 6.98 reps min−1) compared to ART (48.03 ± 5.46 reps min−1).

Fig. 1.

(0.09MB).

Total number of repetitions for passive and active recovery performed on a Treadmill. ART: active recovery on treadmill; PR: passive recovery; SE: standard error; SD: standard deviation.

The two-way ANOVA analysis did not present any significant difference for the interactions between the type of recovery and number of repetitions for subsequent sets (p = 0.064) and between distinct recovery conditions (p = 0.46). However, there was a clear significant reduction observed along the progression of subsequent sets for both recoveries (p = 0.0001). Specifically, the number of repetitions at each set was significantly lower from the second set when compared to the first set for both conditions (Fig. 2). Additionally, the effect of the size of the number of repetitions has been reported as large from the second set for both different types of recoveries (Table 1).

Fig. 2.

(0.11MB).

Repetitions performance in each set for passive and active recovery (mean ± standard deviation). * Significant difference to set 1; # significant difference to set 2; † significant difference to set 3; ART: active recovery on treadmill; PR: passive recovery.

For the RPE, significant increases were observed from the second set for the PR (p = 0.0001) and ART (p = 0.001). A significant increase in RPE values was observed between the PR comparing to the fourth with the second set (p = 0.016) (Table 2).

Among the main findings of this experiment, we highlight the lack of significant difference (p = 0.181) found on the total number of repetitions performed between the distinct PR (25.50 ± 3.13 repetitions) and ART conditions (26.07 ± 2.46 repetitions). Furthermore, no difference was found on interactions between the type of recovery and the number of repetitions for the subsequent sets (p = 0.064). In addition, the AUC values presented no difference between PR (47.05 ± 6.98 reps min−1) and ART (48.03 ± 5.46 reps min−1). Both different recovery models (PR and ART) were implemented by a fixed 2 min of rest between sets and this design showed similar declines on performance from the second set compared to first set (1st > 2nd > 3rd > 4th set) and so on, as expected by the implementation of a short rest interval length. 8–11

Therefore, it became evident that ART did not affect negatively the repetitions performance or even the RPE values. In this manner, we can foresee that the implementation of a similar ART strategy may promote additional benefits related to the recommended total weekly aerobic activity, 2 and has the potential to optimize training duration, 7 without negatively interfering on program efficiency and acute muscular strength performance. This type of strategy might help health professionals who do not possess the necessary time to conduct a training program with high volume and energy expenditure goals. Therefore, a well-elaborated ART design will add tools for athletes or even recreationally trained individuals’ workouts for a great variety of goals such as health, quality of life or even esthetics to be achieved with great effectiveness. 2

In a previous study conducted by Hannie et al. 12 , the authors investigated the influence of AR and PR in strength training. In this investigation, the subjects rested for 2 min for both recoveries, however, when performed AR, part of this period was performed on cycle ergometer at 45% of peak VO2max. The strength exercise analyzed was the barbell bench press and subjects were encouraged to try out as many repetitions they could lift with loads of 65% of 1-RM (15-RM). The authors observed a better recovery between sets, and found an increased production on isometric force within the AR when compared to PR. According to the authors, the AR performed on a cycle ergometer at 45% of VO2max allowed a substantial removal of blood lactate and H+ ions, thus reducing muscle acidosis. This strategy promoted significant better performance of the strength parameters when compared to PR.

Until Hannie et al. 12 , no other publication had addressed the influences of an AR on repetitions performance and force production. The main differences from our study were the type of population investigated and the ergometer. For instance, the present study was conducted with trained individuals, that were used to utilize loads near to 10-RM on their regular routines. Additionally, we chose the treadmill ergometer as the AR strategy. Our results diverge with those found by Hannie et al. 12 possibly by the very distinct repetition zone and intensity (10-RM and 15-RM). Another crucial factor might have been the type of ergometer chosen. For instance, the intensity although the same (45% VO2max), perhaps that when performed on a treadmill may not be sufficient to significantly reduce muscle acidosis and therefore enhance the repetitions performance. It appears that the previously expected reduced muscle acidosis status 20 was not enough to enhance performance on this maximal load range investigated (10-RM). In addition, the very different type of population (trained and untrained) might also have contributed to the different outcome.

In a recent investigation, Scudese et al. 6 analyzed the influences of distinct recovery methods (PR and AR) within a fixed pre-stipulated 2 min of rest between four sets of the barbell bench press exercise for 10-RM in trained men. The PR consisted of subjects lying on the bench for the full 2 min of rest. For the AR, subjects performed rhythmical movements resembling the execution of bench press for the primary muscle with a pace controlled by a metrometer. Similar to our findings, the authors found no differences on bench press performance for both AR and PR strategies. While there were increased values of the RPE observed for both methods of recovery throughout the consecutive sets, higher values were found for the AR compared to PR for the third and fourth sets. These data converge in part with our investigation, since there was a progressive reduction in the number of sets to both recoveries and no difference was found on exercise performance for the distinct rest strategies.

Recent studies have found significant reductions on repetitions performance over consecutive sets, mainly triggered and evidenced by short rest periods (i.e. 2 min). 8,11 For instance, Senna et al. 11 compared repetitions performance of 10-RM intensity with different rest periods for multi and single-joint exercise. The results indicated that shorter rest intervals (such as 1 and 2 min) had greater impact on decreasing the repetition number for bench press. For machine chest fly, significant differences were found for rest periods of 1, 2 and 3 min compared to the longer 5 min. Both exercises presented progressive declines on repetitions performance of over consecutive sets. This study differed from ours mainly due to the implementation of only passive recovery between sets, however, similarly with the present investigation, authors observed progressive reductions for the repetition number when applying 2 min of rest between sets for trained men. With this in mind, we did not found any additional performance advantages when applying the ART due to the similar outcomes observed for both recoveries.

Recently, RPE has been implemented to verify the perceived intensity during strength training exercises and this information can be crucial in order to comprehend the very complex muscle fatigue panorama. 18 For instance, when analyzing the experiment conducted by Scudese et al. 6 , the AR (performed for the same muscle area) caused higher elevations of the RPE during sets when compared to the static PR. However, as the ART in our experiment was conducted on a treadmill, these subjective increases have not been observed. The RPE elevations are usually a response to training strategies that require greater needs of anaerobic glycolysis in muscle area specifically required and thus compensating for incomplete phosphocreatine resynthesis. The emphasis of anaerobic glycolysis energetic system is associated with the accumulation of H+, therefore creating a decreased pH intracellular fluid environment. The result is an afferent response of chemoreceptors and nociceptors that can increase the effort perception. In addition, much like a cascade effect, the central nervous system responds to the increase in RPE by increasing the pulmonary ventilatory response and motor unit recruitment in order to overcome this constantly changing environment. 18

Through our main findings, we can conclude that the inclusion of the ART does not affect repetitions performance and RPE compared to PR. On the other hand, individuals who have the objective of conducting training with loads near 10-RM and additionally aims to increase energy expenditure and optimize the duration of session, should consider applying this method (ART). However, in order to improve knowledge around distinct recovery methods, we strongly recommend future research focusing on other types of verification, such as blood lactate and electromyography in order to better comprehend the peculiarities of the reported phenomenon.

The authors have no conflicts of interest to declare.