June 6, 2023

Effect of Rest Interval Length Between Sets on Total Load Lifted and Blood Lactate Response During Total-Body Resistance Exercise Session

Discover how the duration of rest intervals between sets can impact your workout results and blood lactate levels. Read our study on total-body resistance exercise.

Brent Brookbush

DPT, PT, MS, CPT, HMS, IMT

Research Review: Effect of Rest Interval Length Between Sets on Total Load Lifted and Blood Lactate Response During Total-Body Resistance Exercise Session.

By David Boettcher MSc, BA, NASM CPT, PES, CES & NPTI

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

Original Citation: Lopes, C.R., Crisp, A.H., Schoenfeld, B., Ramos, M., Germano, M.D., Verlengia, R….Aoki, M.S. (2018). Effect of rest interval length between sets on total load lifted and blood lactate response during total-body resistance exercise session. Asian Journal of Sports Medicine 9 (2), doi: 10.5812/asjsm.57500.

Introduction:

Inter-set rest periods is one variable that may be manipulated in a systematic, progressive resistance training program designed to increase strength endurance, maximal strength, power, and/or hypertrophy (1-3). This 2018 study by Brazilian researchers demonstrated that inter-set rest intervals of 60- and 120-seconds resulted in higher total load lifted (TLL) (sets x reps x load) and similar blood lactate response, when compared to 30-second rest intervals. Human movement professionals should consider longer inter-set rest periods, between exercises for similar muscle groups, when an increase in total volume may be beneficial.

Caption: Dr. Brent Brookbush cues Melissa through multi-planer dumbbell press on bench

Dumbbell Press

Study Summary

Study Design	Cross-sectional design
Level of Evidence	IIB - Evidence from quasi-experimental study
Subject Characteristics	Demographics: Gender: Male Number of participants: 10 Body mass: 82.8 + 10.6 kilograms Height: 177.3 + .1 centimeters Age: 23 + 6.5 Inclusion Criteria: Recreational fitness training experience for at least 2 consecutive years Performed at least 3 resistance training sessions per week Familiarity with the exercises being performed Utilized a protocol similar to the study's criteria within their own program design (3-5 sets of 8-12 repetitions) Exclusion Criteria: Previous injuries which prevented participants from completing a resistance training protocol Use of anabolic steroids Use of any performance enhancing supplements
Methodology	All participants determined an intensity/load by performing 10-repetition maximums (RM) for each of the following exercises: bench press, seated low row, shoulder press, back squat, 45° leg press and seated calf raise. After 48 hours, participants returned and were randomly assigned to a 30, 60 or 120 second rest-interval group. Each participant returned 2 more times with 48 hours rest between sessions to ensure all participants performed all 3 inter-set rest period protocols. All resistance training protocols included 4-sets of 10 repetitions for each exercise. Each repetition was performed with a 2-second eccentric and 2-second concentric tempo. Load was adjusted throughout the training session to ensure participants achieved a 10RM for each exercise. Total load lifted was calculated after each exercise bout. Blood samples were also collected for analysis of lactate concentration throughout the training session. Collections were: Pre-exercise (baseline) During exercise (after 3rd exercise) Upon completion of the last exercise 5- and 10-minutes post-exercise
Data Collection and Analysis	Data Collection: Total Load lifted was calculated for each exercise as the number of sets x number of repetitions x external load (kg). Overall blood lactate was analyzed by taking 25 microliters of blood into heparinized capillary tubes stored with 50 microliters of sodium fluoride at 1%. Data Analysis: A one-way analysis of variance (ANOVA) followed by Bonferroni's post-hoc test was used for the comparison between total load lifted and blood lactate. Results were based on the following criteria using Cohen's formula for effect size (ES) (Mean 1 - Mean 2 / pooled standard deviation): <0.35 trivial/no effect 0.35 - 0.8 small effect 0.8 - 1.5 moderate effect > 1.5 large effect Significance was set to a p value of <0.05
Outcome Measures	Total load lifted between inter-set rest intervals Peak blood lactate concentration compared to baseline (mMoles) for each inter-set rest interval.
Results	Total Load Lifted (TLL): TLL was significantly lower for the 30-second inter-set rest session (26382.0 +/- 4100.3 kg, p < 0.001). No significant difference in TLL between the 60- and 120-second inter-set rest sessions (p > 0.05, ES = 0.29). Blood Lactate: No significant blood lactate differences were observed between any of the inter-set rest intervals or sessions (p > 0.05). Blood lactate levels showed a similar increase between all sessions. 30-second mean: 7.05 +/- 1.69 mMoles 60-second mean: 7.26 +/- 2.77 mMoles 120-second mean: 6.90 +/- 3.79 mMoles
Researchers' Conclusions	Inter-set rest intervals of 60- and 120-seconds demonstrated a higher total load lifted with similar blood lactate response compared to a shorter inter-set rest interval of 30-seconds during full body resistance exercises. Longer inter-set rest intervals should be used when the objective of an exercise session is a higher volume of training.

How This Study Contributes to the Body of Research:

This cross-sectional study examined the effects of different inter-set rest periods on total load lifted (TLL) (sets x reps x load), and blood lactate concentrations during full-body resistance training in men. Similar to previous research, this study demonstrated that shorter inter-set rest periods (less than 60 seconds) reduced TTL (17-19). Unique to this study, a full-body resistance training program protocol was used, and blood lactate response was tested showing no significant difference between inter-set rest periods. This study supports the growing body of evidence that longer inter-set rest intervals may be beneficial.

How the Findings Apply to Practice:

The findings of this study demonstrate that 60 and 120 second inter-set rest periods can significantly increase total load lifted (TLL), without impacting blood lactate. The use of longer (>60-second) inter-set rest periods is consistent with additional research, with some studies showing longer inter-set rest periods of up to 3-minutes being beneficial (14, 17, 22). This study seems to suggest that no additional benefit is attained from rest intervals longer than 60 seconds, which may aid the human movement professionals in creating effective and time-efficient programming.

Strengths

The exercises used in this study are commonly used in resistance training programs, allowing for easy application in a professional setting.
Repetitions, range of motion and cadence were standardized for all exercises, exercise sessions were performed at the same time each day, and sessions were monitored by a coach/trainer to ensure reliability of testing protocol.
The use of a randomized cross-over design is a good choice for strength training studies like this, as it allows each individual to act as their own control and test population.

Weakness and limitations

The duration of the study was short, with one session of each inter-set rest interval tested. It is unknown whether repeated sessions would have resulted in adaptation to the shorter inter-set rest interval.
A small sample size of experienced lifters was used, which minimizes the generalizability of the study.
No structured exercise order/protocol was established or identified, decreasing the repeatability of the study.

How Does It Relate to Brookbush Institute Content?

The Brookbush Institute (BI) is continuing to develop and refine acute variable recommendations for optimal muscular strength, hypertrophy, power, and endurance adaptations based on all available evidence. The findings of this study demonstrate that for moderate load (8 - 12 reps), total body routines, 30 seconds may be an insufficient inter-set rest interval; however, 60 and 120 second rest intervals resulted in similar total load lifted (overall workload). This study will be integrated with the findings of other studies to ensure the BI's inter-set rest interval recommendations allow for optimal rest without adding unnecessarily to the total time of a training session.

Sample Strength Training Videos Below:

Back Squat from Brent Brookbush.

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