Research Review: Longer Interset Rest Periods Increase Repetition Performance in Both Multi- and Single-Joint Exercises

By Nicholas Rolnick SPT, MS, CSCS

Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Senna G, Willardson JM, Salles BF, Scudese E, Carneiro F, Palma A, Simão R. The effect of rest interval length on multi and single-joint exercise performance and perceived exertion. J Str Cond Res. Nov 2011; 25(11): 3157-3162. ABSTRACT

Why the Study Is Relevant: The American College of Sports Medicine suggests 2-3 minutes of interset rest for multi-joint movements, and 1-2 minutes rest for single-joint movements (1). This 2011 study by Brazilian researchers suggests longer rest periods (3 - 5 minutes) promote completion of more repetitions and more total volume, especially between multi-joint movements.

Caption: Model: Nicholas Rolnick

Bicep Curls was one of the single-joint exercises in this study. Model: Nicholas Rolnick

Study Summary

Study Design	Cohort Study, within-Subjects Design
Level of Evidence	IB Evidence from at least one randomized controlled trial
Subject Characteristics	Age (years) ± (Standard Deviation): 23.6 ± 2.64 Weight (kg): 76.46 ± 7.53 Height (cm): 177 ± 6.98 Bench press relative strength (kg*kg-¹ bodyweight) - 1.53 ± 0.25 Gender: Male Number of participants: 15 Inclusion Criteria Weightlifting at least 3x/week for the past year Perform a bench press with at least 1.25x body mass No other physical activity throughout the duration of the study Exclusion Criteria No medical conditions that could influence the training program No history of anabolic or ergogenic substances that could influence the study's primary outcome (repetitions per set)
Methodology	Prior to the start of the study, each subject attended four sessions to ensure familiarity with the exercise protocol, and determine 10-repetition maxes (RM) for the exercises within the experimental design. In these sessions, 10-RM values were determined for each exercise and reliability testing was done. Free weight bench press (BP) and machine leg press (LP) were done in the first session; machine chest fly (MCF) and machine leg extensions (LE) were done in the second. 10RM protocol consisted of each subject lifting gradually increasing weight, until a weight was attempted that prevented an 11th repetition. Subjects were given a minimum of 3 trials and 5 minutes between attempts. Ten minutes of rest was taken between different exercises within a session. The most weight lifted for 10 repetitions over the two days was used as the participants 10RM. Each session was separated by 48 hours, and subjects were instructed not to perform additional weight training programs. To minimize errors in the protocol, each subject received standardized instructions on the protocol and exercise technique. Subjects also performed each exercise in the same body position (same hand width during BP for example) and received verbal encouragement from the researchers. All plates were massed to ensure precision in loading. Forty-eight to 72 hours after the 10RM testing, subjects took part in the first of 12 exercise sessions, with each session separated by at least 48 hours. Each subject performed each exercise and rest period in a randomized within-subjects design over the course of the 12 sessions. A warm-up prior to the 10RM testing consisted of 2 sets of 12 repetitions at 40% of the 10RM of the exercise tested. Two minutes were given between the warm-up and the start of the first experimental set. Subjects performed 5 sets of 10RM at the specified rest interval. The protocol did not control for repetition velocity, but the participants were instructed to move the weight in a "smooth and controlled" manner. After each set, the Omni-Res rate of perceived exertion (RPE) and the number of repetitions were recorded. Statistical analyses used the Shapiro-Wilk test and Bartlett criterion to meet assumptions of normality and homogeneity of variance. Analysis of variances (ANOVA) were calculated to determine the effect that interset rest intervals have on number of repetitions in the multi- versus single-joint exercises. Effect sizes were calculated to investigate the magnitude of the effect of the interset rest interval on repetitions during the different exercises.
Outcome Measures	Test-retest reliability measurements for each exercise and 10RM procedures Number of repetitions performed in the BP, MCF, LP and LE in each of the interset rest conditions across 5 sets Effect sizes for each RPE in the BP, MCF, LP and LE in each of the interset rest conditions across 5 sets
Results	Excellent test-retest reliability was observed for each exercise (r = 0.92-0.98) and no significant differences were observed in the test-retest 10RM testing (p > 0.05) Repetitions Completed BP repetitions were significantly greater in the 3- and 5- minute rest intervals when compared to the 1-minute rest intervals (p ≤ 0.05); No significant differences were detected between 3- and 5-minute rest intervals groups. Significant differences were detected in MCF, LP, and LE between all rest times (1 < 3 < 5; p ≤ 0.05) Trend: Declines in repetitions performed (relative to the first set) were present in all conditions, but appeared earlier in 1-minute rest (set 2) than in the 3- or 5-minute rest groups (set 3) Effect Sizes: Effect sizes demonstrated large repetition reductions in all rest groups, with 1-minute rest periods having the largest effect size for repetition reduction when compared to the 3- and 5-minute group across sets. Effect sizes ranged from 0 to 28.52 (in set 5 of the 1-minute group during BP), with all effect sizes > 1 except for 4 data points, suggesting a large effect of rest on repetition completion. Trend: BP and LP exhibited significantly higher magnitudes of repetition decline over successive sets when compared to MCF and LE. Significant increases in RPE were observed for all conditions and all exercises, with 1-minute rest group reporting significantly higher RPE than the 3- and 5-minute groups. RPEs varied from 6-9/10 in all cases.
Our Conclusions	Modulating the interset rest period depending on the exercise can have important implications on volume (reps x sets) and volume load (reps x sets x load). This may have implications on interest rest periods for all phases of resistance training programming (endurance, hypertrophy, strength and power).
Researchers' Conclusions	Increasing interset rest periods can significantly affect the number of repetitions completed and the perceived exertion across a 5-set 10RM exercise workout in resistance-trained males. Five-minute interset rest periods confer the largest benefit to maintaining the amount of repetitions completed across sets, with 1-minute rest intervals showing the opposite trend. All exercises showed significant increases in RPE with increased sets, with 1-minute rest interval group showing the highest RPEs.

Caption: Bench press was one of the multi-joint exercises used in this study.

Bench press was one of the multi-joint exercises used in this study.

Review & Commentary:

The American College of Sports Medicine suggests 2-3 minutes of interset rest for multi-joint movements, and 1-2 minutes rest for single-joint movements (1). This study added to a growing body of literature suggesting that longer rest periods may be more beneficial (2 - 4).

The study had many methodological strengths, including:

The protocol was very clear, allowing for replication. The authors described the subjects, wrote detailed descriptions of how the experiment was carried out, and used appropriate statistical analyses to draw their conclusions. The randomized within-subject design also strengthens the results, as subjects underwent each experimental condition. The data published was also comprehensive, reducing reporting bias.
The study used 4 exercises frequently used in resistance-training programs. Inclusion of these exercises increases clinical relevancy and generalizability.
The authors provided reliability data for each of the protocols and assessment tools associated with their primary outcomes.
Previous studies have investigated the effect of interset rest periods on exercise performance (completed repetitions), but no studies have directly compared multi- and single-joint exercises in one intervention. This study filled a gap in the literature by comparing these types of exercises and the effect on exercise performance and perceived exertion.

Weaknesses that should be noted prior to clinical integration of the findings include:

The subject size was fairly small, only fifteen resistance-trained males participated in this study. While significance was achieved between groups, it is not known whether or not additional subjects would have further stratified the results. Specifically, differences between 3- and 5-minute groups could hold important clinical significance with respect to exercising time.
There was no mention of the subjects' nutritional intakes. Nutrition could have influenced how subjects responded to the training protocol. Future research should include a diet journal to minimize the chance that diet influenced outcomes.
The study investigated 15 men, using 4 machine exercises (2 multi-joint, 2 single-joint) commonly used in fitness, rehab and performance settings. Results may not be generalizable to other groups or modalities. Future research should expand on the types of exercises used and vary the loading schemes to increase generalizability.

Why This Study Is Important

The study provides evidence that longer interset rest periods (3- and 5-minutes) aid in maintaining repetition ranges from set to set when compared to shorter rest periods, regardless of whether a single- or multi-joint is performed. All groups exhibited similar patterns in repetition performance and rate of perceived exertion (RPE), but the pattern was most pronounced in the 1-minute group. The results indicate that if volume is a resistance-training goal, trainees should favor longer (3 - 5 minute) over shorter (1-minute) interset rest periods.

Repetitions completed per set by each subject decreased independently of rest time, while RPE increased. RPE could be primarily influenced by the underlying physiological mechanisms responsible for muscle recovery. Although all groups' RPE ratings increased, RPE increased more significantly across sets in the 1-minute interset rest group because of the acute unavailability of muscle energy stores.

How the Findings Apply to Practice

When designing an exercise regimen for clients/patients, it is important to understand how the duration of interset rest periods influence performance. It is one variable out of many (frequency, volume, load, repetitions, etc.) that can be manipulated to achieve rehab, fitness and performance goals. The findings of this study, indicate that longer interset rest periods may help maintain target rep ranges from set to set, and increase the total volume of exercise during a workout. Although further research is needed to determine whether the change in volume resulting from increased interset rest periods would lead to increases in hypertrophy, strength and performance, initial research appears to be favorable (2-4).

Related Brookbush Institute Content

Based on an individual's training goals, the Brookbush Institute (BI) recommends varying interset rest periods with the intent of optimizing training session time toward the individual's goals. The results of this study indicate that increased interset rest allows for better maintenance of training volume, regardless of the type of exercise (single- or multi-joint). This may indicate that the Brookbush Institute should modify the recommended interset rest periods currently promoted in our acute variables tables.

This research may also support the use of circuit training; the preferred routine design of the Brookbush Institute. If at least a 3 - 4 exercise circuit is designed, by default, large interset rest periods would result before repeating the same exercise. If careful consideration is given to choose exercises that target different muscles (for example, Total Body, Chest, Back, Legs, Corrective Exercise/ActiveRest), large interset rest periods would also occur before targeting the same muscle group. Further research is needed to determine whether performing exercises for different muscles during interset rest periods will have an affect on the ability to maintain rep ranges set after set.

Last, although the results of this and other studies (2-4) suggest longer interset rest periods are beneficial, the total length of a session must be considered. If a client/patient has 60 minutes to compete a training session, the additional repetition or 2 repetitions that may be achieved by 5 minute rest times, may not be worth the decrease in volume when compared to the number of sets that can be competed if 2 - 3 minute rest periods are used.

The following videos depict some of the commonly used resistance training exercise used by the Brookbush Institute, including a couple used in this study.

Brookbush Institute Videos

Back Squat

Bench Press and Chest Press

Front Squat to Shoulder Press

Squat to Row

References:

American College of Sports Medicine. Position stand on progression models in resistance exercise for healthy adults. Med Sci Sports Exerc. 2009; 41: 687-708.
Schoenfeld, B.J., Pope, Z.K., Benik, F.M., Hester, G.M., Sellers, J., Nooner, J.L., Schnaiter, J.A., Bond-Williams, K.E., Carter, A.S., Ross, C.L. and Just, B.L. Longer interset rest periods enhance muscle strength and hypertrophy in resistance-trained men. J Str Cond Res. July 2016; 30(7): 1805-181
Willardson JM, Burkett LN. The effect of rest interval length on the sustainability of squat and bench press repetitions. J Strength Cond Res. May 2006; 20(2): 400-403.
Senna, G., Willardson, J. M., de Salles, B. F., Scudese, E., Carneiro, F., Palma, A., & Simão, R. (2011). The effect of rest interval length on multi and single-joint exercise performance and perceived exertion. The Journal of Strength & Conditioning Research, 25(11), 3157-3162
Astrand PO, Rodahl K, Dahl HA, Stromme SB. Textbook of work physiology: physiological bases of exercise. 3rd ed. 1986; New York: McGraw-Hill.
Schoenfeld BJ, Ogborn D, Krieger JW. Dose-response relationship between weekly resistance training volume and increases in muscle mass: a systematic review and meta-analysis. J Sports Sci. July 2016; 19: 1-10.

Questions, comments, and criticisms are welcomed and encouraged -

The Effect of Rest Interval Length on Multi and Single-Joint Exercise Performance and Perceived Exertion

Research Review: Longer Interset Rest Periods Increase Repetition Performance in Both Multi- and Single-Joint Exercises

Brookbush Institute Videos

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