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Effect of Different Interset Rest Intervals on Performance of Single and Multijoint Exercises With Near-Maximal Loads

Senna, Gilmar W.; Willardson, Jeffrey M.; Scudese, Estevão; Simão, Roberto; Queiroz, Cristiano; Avelar, Raoni; Martin Dantas, Estélio H.

Journal of Strength and Conditioning Research: March 2016 - Volume 30 - Issue 3 - p 710–716
doi: 10.1519/JSC.0000000000001142
Original Research
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Senna, GW, Willardson, JM, Scudese, E, Simão, R, Queiroz, C, Avelar, R, and Dantas, EHM. Effect of different interset rest intervals on performance of single and multijoint exercises with near-maximal loads. J Strength Cond Res 30(3): 710–716, 2016—The aim of this study was to investigate the acute effects of different interset rest intervals on performance of single- and multijoint exercises with near-maximal loads. Fifteen trained men (26.40 ± 4.94 years, 79.00 ± 7.10 kg, 176.6 ± 6.06 cm, 11.80 ± 2.47% body fat, and bench press relative strength: 1.26 ± 0.19 kg·kg−1 of body mass) performed eight sessions (2 exercises × 4 interset rest intervals); each consisting of 5 sets with a 3RM load. The exercises tested were the machine chest fly (MCF) for the single-joint exercise and the barbell bench press (BP) for the multi-joint exercise with 1, 2, 3, and 5 minutes of rest between sets. The results indicated that for the MCF, significantly higher total number of repetitions were completed for the 2- (12.60 ± 2.35 reps; p = 0.027), 3- (13.66 ± 1.84 reps; p = 0.001), and 5-minute (12.93 ± 2.25 reps; p = 0.001) vs. the 1-minute (10.33 ± 2.60 reps) protocol. For the BP, a significantly higher total number of repetitions were completed for 3- (11.66 ± 2.79 reps; p = 0.002) and 5-minute (12.93 ± 2.25 reps; p = 0.001) vs. the 1-minute protocol (7.60 ± 3.52 reps). In addition, subjects completed significantly higher total number of repetitions for the 5-minute (12.93 ± 2.25 reps; p = 0.016) vs. 2-minute (9.53 ± 3.11 reps) protocol. Both exercises presented similar and progressive reductions in repetition performance for all rest protocols along the 5 sets, starting as soon as the second set for the shorter 1-minute rest protocol. In conclusion, to maintain the best consistency in repetition performance, rest intervals of 2 minutes between sets are sufficient for the MCF and 3–5 minutes for the BP. Thus, it appears that longer acute recovery time is needed for a multijoint (core) exercise such as the BP vs. a single-joint (assistance) exercise such as the MCF.

1Nursing and Biosciences Post-Graduation Program (PPgEnfBio), Doctorate of Federal University of State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil;

2Biosciences Laboratory of Human Movement (LABIMH), Tiradentes University (UNIT), Aracajú, Brazil;

3Kinesiology and Sports Studies Department, Eastern Illinois University, Charleston, Illinois;

4School of Physical Education and Sports, Federal University of Rio de Janeiro (EEFD/UFRJ), Rio de Janeiro, Brazil; and

5Health Science Center, Catholic University of Petrópolis, Rio de Janeiro, Brazil

Address correspondence to Gilmar W. Senna, sennagw@gmail.com.

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Introduction

For the past 2 decades, the rest interval between sets has received much attention from resistance training researchers. It has already been well established that the rest interval between sets, independent of other prescriptive variables, has significant acute effects on repetition performance (11–14,16–19) and neuromuscular (19), endocrine (4,9), and cardiorespiratory responses (10). Differences in acute responses may result in expression of different adaptations over time with emphasis on maximal strength, hypertrophy, power, and localized muscular endurance (2).

Recent studies have shown that longer rest intervals between sets (i.e., 5 minutes) allow for greater recovery and consistency in repetition performance with 8 to 15RM loads (8,12,14,16–18). However, Scudese et al. (11) was the first to investigate the effects of rest interval manipulation with a near maximum 3RM load for the barbell bench press (BP) exercise and observed that 3-minute rest between sets allowed for sufficient recovery to maintain consistency in the repetitions completed per set.

It is recommended that individuals with specific muscular strength development goals should train with loads ranging from 1 to 6RM (2). The ability to maintain consistency in the repetitions completed with a given load over a series of sets may enhance adaptational processes, leading to greater strength gains over time (14). Regarding the latest recommendations on strength training for healthy adults, the American College of Sports and Medicine (1,2) suggested prescription of interset rest intervals ranging from 2 to 3 minutes for multijoint (core) exercises and 1–2 minutes for single-joint (assistance) exercises.

To our knowledge, very few studies have investigated the potential acute interactions between different rest intervals between sets and single and multijoint exercise performance (13,14). Specifically, Senna et al. (14) observed that for both single- and multijoint exercises, repetition performance patterns and perceived exertion were independent of the rest interval between sets. In addition, Senna et al. (13) also observed similar repetition performance patterns between machine chest fly (MCF) and BP exercises; albeit, for the single-joint exercise (MCF), the blood lactate response was significantly less for the longer rest interval (3 minutes) vs. the shorter rest interval (1 minutes) between sets. By contrast, for the multijoint exercise, there was no significant difference in the blood lactate response, irrespective of the rest interval between sets (13). These studies (13,14) indicate that the time course of interset recovery might be different between single- and multijoint exercises when using 10RM loads.

However, there is a gap in the literature regarding the effect of different rest intervals between sets on single- and multijoint exercise performance with near-maximal loads (i.e., 3RM). Such a comparison may improve the efficacy of resistance training prescription and subsequent strength adaptations over time. Therefore, to increase the growing body of knowledge regarding this theme, the aim of this study was to investigate the acute effects of different interset rest intervals (1, 2, 3, and 5 minutes) on performance of single- and multijoint exercises with near-maximal loads (i.e., 3RM). The single- (assistance) and multijoint (core) exercises selected for this study were the MCF and barbell BP, respectively.

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Methods

Experimental Approach to the Problem

Forty-eight to 72 hours after proper familiarization and determination of 3RM loads for the MCF and BP, subjects underwent 8 different training sessions with 48 hours between sessions. Sessions were performed in random order with a specific combination of exercise (MCF or BP) and rest interval (1, 2, 3, or 5 minutes). Five sets were performed for maximal repetitions with the predetermined 3RM load. The total repetitions and rating of perceived exertion (RPE) were recorded after each exercise set.

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Subjects

Fifteen trained men with at least one year consistent resistance training experience were asked to participate (26.40 ± 4.94 years, 79.00 ± 7.10 kg, 176.60 ± 6.06 cm, 11.80 ± 2.47% body fat, bench press relative strength: 1.26 ± 0.19 kg·kg−1 of body mass). The following inclusion criteria were adopted to standardize subject selection: (a) training frequency of at least 4 times per week, with session duration approximately 1 hour, and rest intervals between sets ranging from 1 to 2 minutes; (b) nonusage of any ergogenic substance that would enhance repetition performance; (c) no acute or chronic injuries that would affect MCF and BP performance; and (d) did not engage in intense activity on test days. Before data collection, all subjects answered “no” to all questions on the PAR-Q (15). The study procedures had been previously approved by the Catholic University of Petrópolis ethics committee. Participants read and signed an informed consent after being informed of the testing procedures according to the Declaration of Helsinki.

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Determination of Three Repetition Maximum

After 2 familiarization visits, subjects performed four 3RM load testing sessions for the MCF and BP exercises. Subjects performed only one exercise per visit, in alternated order on nonconsecutive days for test and retest sessions. The following strategies were adopted to minimize measurement error: (a) standard instructions concerning the testing procedures and exercise technique were given before all tests (3); (b) body position was held constant; (c) verbal encouragement was given (7); and (d) the mass of all plates and bars was determined through a precision scale. The 3RM test has been previously described (14). Briefly, the initial loads for 3RM testing were estimated from loads used by each subject during the course of their daily-periodized strength training routines. From this point, the load modification pattern followed a 2 kg for BP and 2.5 kg for MCF (total minimal modification) manipulation for each attempt, and it was held consistent for each subject. The last successful lift was recorded as the 3RM; the greatest load lifted over the 2 testing sessions was assumed as the 3RM load. The greatest load lifted over the 2 testing sessions for each exercise was recorded as the 3RM load. Each testing session was separated by at least 48 hours. Subjects performed a maximum of five attempts during each visit, with at least 5–10 minutes of passive rest between attempts (14).

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Rate of Perceived Exertion Procedures

The OMNI resistance exercise scale (6) was implemented to obtain the RPE values. Subjects were familiarized with the OMNI Scale the week before load tests. Subjects were asked to choose a number based on their perceived exertion or subjective intensity of effort, strain, discomfort, and/or fatigue experienced during the exercise session (6). The MCF and BP were practiced during the familiarization sessions for three sets of 15 repetitions with 3-minute rest intervals between sets with estimated loads based on subjects' daily training routines.

Immediately after each exercise set, subjects were asked to identify their RPE to provide a subjective measure of the exertion level (11,14).

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Experimental Procedures

Forty-eight to 72 hours after the last 3RM test, subjects completed the first of 8 different visits (2 sessions per week). In each session, subjects performed 5 sets with 3RM loads in a randomized design that was implemented to combine each exercise (MCF or BP) with a given rest interval (1, 2, 3 or 5 minutes). Before each protocol, subjects engaged in a warm-up consisting of 2 sets of 12 repetitions with 40% of the 3RM load for the given exercise for that session. Then, a 3-minute rest was allowed between the warm-up sets and training protocol. Subjects were verbally encouraged (7) to perform 5 sets until voluntary exhaustion, and no attempt was made to control the repetition velocity. Each subject was instructed to use a smooth and controlled movement. In addition, the total number of repetitions completed and RPE OMNI-Res scale values (6) were recorded after each exercise set completion.

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Statistical Analyses

An alpha value of p ≤ 0.05 was used to establish the significance of comparisons. To verify test and retest reproducibility, the intraclass correlation coefficient was implemented (ICC). One-way ANOVAs were conducted to analyze differences in total number of repetitions completed for each exercise, repetitions completed on each individual set (for every exercise) and on distinct rest conditions. If necessary, further comparisons were made via Bonferroni post hoc test.

In addition, to determine the magnitude of the findings, the effect size (ES; the difference between the pretest score and the posttest score divided by the pretest SD) statistics were calculated for each exercise set of every rest condition, and the thresholds proposed by Cohen (5) were applied to determine the magnitude of effects. The Friedman test was used to analyze RPE scores and compare differences after each exercise set within and between rest interval protocols. If necessary, a Dunn post hoc test was applied for multiple comparisons. The SPSS software 21.0 version was used for statistical analyzes (IBM, Inc).

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Results

An excellent test/retest correlation was found for the 3RM loads using the ICC (MCF, r = 0.98; BP, r = 0.99), and no differences were found between the test/retest loads via paired Student's t-test (p ≤ 0.05). The results indicated that for the MCF, significantly higher total number of repetitions were completed for the 2- (12.60 ± 2.35 reps; p = 0.027), 3- (13.66 ± 1.84 reps; p = 0.001), and 5-minute (12.93 ± 2.25 reps; p = 0.001) vs. the 1-minute (10.33 ± 2.60 reps) protocol. For the BP, a significantly higher total number of repetitions were completed for 3- (11.66 ± 2.79 reps; p = 0.002) and 5-minute (12.93 ± 2.25 reps; p = 0.001) vs. the 1-minute protocol (7.60 ± 3.52 reps). In addition, subjects completed significantly higher total number of repetitions for the 5-minute (12.93 ± 2.25 reps; p = 0.016) vs. 2-minute (9.53 ± 3.11 reps) protocol. Both exercises presented similar and progressive reductions in repetition performance for all rest protocols along the 5 sets, starting as soon as the second set for the shorter 1-minute rest protocol. Briefly, in MCF, significant reductions in repetition numbers were evident from the second set for 1-, 2-, and 3-minute rest conditions. For the 5-minute rest condition, reductions were evident at the fourth set compared with the initial set. For BP exercise, significant reductions in repetition numbers appeared at the second set for 1-minute, the third set for 2-minute, and the fourth set for 3- and 5-minute rest conditions. In addition, for MCF and BP, significant differences were observed between the shorter 1-minute rest condition as early as the second set compared with the longer 3- and 5-minute rest conditions. Data are clearly presented in Table 1 and Figures 1 and 2.

Table 1

Table 1

Figure 1

Figure 1

Figure 2

Figure 2

The ESs were calculated using the repetition number executed in the first set (as the pretest value) and repetition number throughout the second and between the fifth set (as the post-test scores), along with standard derivation of the first set (as the pretest standard derivation). Most ES data indicated large magnitude declines in repetition performance for both exercises across rest conditions. The magnitude of declines increased over successive sets in all rest interval conditions independent of the exercise mode. For both exercises, the declines were larger with lesser rest between sets (Table 2).

Table 2

Table 2

For the MCF, the 1-minute rest protocol evidenced significantly greater RPE values vs. the other longer rest conditions (i.e., 2, 3 and 5 minutes). For the other rest protocols (2, 3 and 5 minutes), MCF differences in the RPE were only evident between the first and fifth sets. For the BP, significant increases in the RPE were significantly greater from the third to fifth sets for all rest conditions (Table 3).

Table 3

Table 3

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Discussion

In general, the findings of this study indicated that when implementing a 3RM load for the MCF and BP, a 1-minute rest interval between sets resulted in a significant reduction in the total repetitions completed and a greater RPE (pre and post-set values) over 5 consecutive sets. This outcome is in contrast to the increased total repetitions completed and significantly lower RPE for the protocols that involved a longer rest interval between sets (2, 3 and 5 minutes), regardless of exercise mode (MCF and BP). However, the overall repetition reductions observed for the MCF were less evident vs. the overall repetition reductions for the BP with 2-, 3-, and 5-minute rest between sets. The same trend was observed in RPE values between exercises at these rest interval lengths.

Therefore, it appears that at rest interval lengths greater than or equal to 2 minutes between sets, differences between the MCF and BP became increasingly apparent in the overall reduction in repetition performance and RPE. From a practical standpoint, this study suggests that for adequate maintenance of repetitions over 5 sets, a 2-minute rest interval might be sufficient for the MCF; whereas, a 3-minute rest interval might be suitable for the BP exercise. Thereby, longer rest periods between sets (i.e., 5 minutes) will increase the total duration of a training session, apparently without providing additional benefits to repetition performance when implementing 3RM loads.

According to the American College of Sports Medicine (2), to maximize the muscular strength development, the ideal load intensity must range between 1 and 6RM. In addition, the latest recommendations (1,2) suggests that for muscle strength development purposes, rest lengths should be 1–2-minutes between sets for single-joint (assistance) exercises and 2–3 minutes between sets for multijoint (core) exercises. However, the present study is the first to assess acute repetition performance in the context of a single- (i.e., MCF) and multijoint exercise (i.e., BP) when using a near-maximal load (i.e., 3RM). Thus, we can state based on our findings that the present study agrees with the current rest recommendation. Our data suggest that to maximize repetition performance, at least 2 minutes of rest between sets was sufficient for the MCF and at least 3 minutes was sufficient for the BP.

Recently, 2 studies investigated the influence of different rest intervals in single- and multijoint exercises (13,14) in other intensity zones. Senna et al. (14) compared repetition performance in single- and multijoint exercises, for exercises incorporating the pectoralis major and quadriceps with a 10RM load. Repetition performance and RPE were compared with 1-, 3-, and 5-minute rest intervals between sets of single- (MCF and leg extension) and multijoint (BP and leg press) exercises. The results indicated that for the BP, significantly greater total repetitions were completed for the 3- and 5-minute protocol vs. the 1-minute protocol. No significant differences were evident between the 3- and 5-minute rest conditions for the BP. For the other exercises (i.e., leg press, leg extension, and MCF), significant differences were evident between all rest conditions (1- < 3- < 5-minute 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-minute and by the third set for the 3- and 5-minute conditions.

In another study, Senna et al. (13) compared the effect of different intervals on single- and multijoint exercise repetition performance, perceived exertion and blood lactate. Twelve trained men completed 5 sets of the BP and MCF with 10RM loads to failure with 1- or 3-minute rest intervals between sets. It was found that significantly greater total repetitions were completed for the 3-minute rest protocol vs. the 1-minute rest protocol for both exercises. Regarding the RPE, progressive increases occurred after the third set for all conditions tested. For blood lactate concentrations, the BP demonstrated significant increases immediately and fifteen minutes post-exercise vs. baseline for both conditions (1 and 3 minutes). Conversely, for the MCF, significantly greater increases in blood lactate were observed for the 1-minute vs. the 3-minute condition at the same time points after exercise.

The studies conducted by Senna et al. (13,14) resembled the present study with similar performance decreases found in both exercises (BP and MCF) for the 1-minute rest condition. In addition, another key similarity was the lower RPE values for the single-joint exercises, indicating a decreased fatigue status associated with the use of lesser muscle mass. However, one of the major differences in the present study vs. Senna et al. (13,14) was the load range (i.e., 3 vs. 10RM). This indicates that performance will be similarly affected by the rest interval condition, irrespective of the load intensity.

However, this was not the first study that compared multijoint exercise repetition performance and RPE values with near maximum loads. In fact, the study conducted by Scudese et al. (11) was the first study to analyze the effects of different rest interval lengths on 3RM BP performance and RPE values. Sixteen trained men performed 4 visits for 1-, 2-, 3-, and 5-minute rest intervals between 5 consecutive sets. Scudese et al. (11) found increased total BP repetitions completed with 2-, 3-, and 5-minute vs. 1-minute rest between sets. Declines in performance (relative to the first set) were observed starting as early as the second for the shorter 1 minute and only at the fifth set for all of the other rest conditions (2-, 3- and 5-minute). The present study resembled Scudese et al. (11) in the load range implemented (3RM). In addition, the outcomes for the BP exercise followed similar repetition patterns of decline over consecutive sets. However, the present study went further by investigating the MCF with a 3RM load. The present study showed a distinct difference between the MCF and BP specifically beginning at the 2-minute rest condition, at which significantly greater total repetitions were performed over 5 sets for the MCF vs. the BP.

Others studies have verified the differences in repetition performance with different rest interval lengths between sets (8,12). Specifically, Senna et al. (12) compared repetition performance during 4 sessions that included 3 exercises for the lower body (i.e., leg press, leg extension and leg curl) and 3 exercises for the upper body (i.e., BP, MCF, and triceps pushdown), performed for 3 sets with a 10RM load, and either 2- or 5-minute rest intervals between sets. For the 2-minute sessions, most exercises presented declines in repetition performance as early at the second set vs. the first set (excluding the MCF) and for the third set vs. the first and second sets (excluding leg extension). For the 5-minute sessions, 3 of the 6 exercises presented declines in repetitions from the third set vs. the first set (leg press, leg curl, and triceps pushdown), and 2 of the 6 exercises presented declines from the third set vs. the second set (leg curl and triceps pushdown). The total repetitions completed at the end of the session were significantly greater for 5 minutes when vs. 2-minute rest protocol (12).

This study (12) differed from the present study, in that the accumulated fatigue from the initial exercises performed during an entire training session probably impacted the repetition performance of the exercises conducted later in the session. In addition, our study was designed with only one exercise per visit and implemented a higher load (3RM). However, consistent with this study, the BP and MCF presented distinct repetition performance patterns with a key threshold for differences being exhibited with 2-minute rest between sets.

The RPE values have been used for assessing the relative intensity of resistance exercise (6). Prior studies (12,14) reported that the RPE increased over the course of consecutive sets when comparing 1-minute vs. 3- or 5-minute rest between sets when using a 10RM load. More recently, Scudese et al. (11) found that the RPE was also lower when longer rest intervals were applied between sets when using a 3RM load.

In the present study, significant increases were also evident in RPE for the 1-minute rest condition starting from the third set through the fifth set for both exercises. For the other rest conditions (2, 3 and 5 minutes), the BP exercise triggered significant increases starting from the third set through the fifth set. For the MCF exercise, a significant increase in RPE was observed only at the fifth set for the 2-, 3-, and 5-minute rest conditions. This outcome suggested a greater fatigue rate perceived when under the 1-minute condition vs. the longer rest conditions, independent of the exercise mode (multi- or single-joint) implemented.

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Practical Applications

Our results seems to be in accordance with the current state of the art in resistance training, suggesting that distinct rest interval lengths between sets will trigger different acute performance outcomes tending toward reductions in repetition performance over multiple sets with shorter vs. longer rest lengths (11,12,14,16–18). More specifically, when using a near-maximal load (i.e., 3RM), we observed a similar pattern of performance reduction for both exercises modalities (multi- and single-joint) with a key subtle difference. Our data suggest that to maximize repetition performance, at least 2 minutes of rest between sets was sufficient for the MCF and at least 3 minutes of rest was sufficient for the BP.

Thus, for different exercise modes (single- and multijoint), the main difference in repetition performance became evident around the 2-minute mark. This data might contribute to future recommendations focused on strength development for single- and multijoint exercises performed with near-maximal loads. However, we strongly recommend that future studies should evaluate distinct exercise schemes, other near-maximal load ranges (1 to 6RM), and whole-body training sessions.

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Keywords:

muscle strength; weight lifting; physical fitness

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