Influence of Strength Level on the Rest Interval Required During an Upper Body Power Training Session

Research Review: Influence of Strength Level on the Rest Interval Required During an Upper Body Power Training Session

By Crystal Chariton MA, LMT, NSCA- CSCS, NASM- CPT, USAW

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

Original Citation:

Hernandez-Davo, J., Ruiz, J., & Sabido, R. (2017). Influence of strength level on the rest interval required during an upper-body power training session. Journal of Strength and Conditioning Research, 31(2), 339-347. ABSTRACT

Why the Study is Relevant:

Most sports and some activities of daily living require significant amounts of power, that is, the "quick production of force." It has been suggested that more strength will result in more power, because strength (force production) is a component of power (force production/time) (1). Many of the variables involved in prescribing power training have been studied, but research on the inter-set rest interval required to maintain power output is limited and inconclusive (2,3). Further, previous studies have not attempted to evaluate the influence of strength on optimal inter-set rest interval. This 2017 study investigated the influence of strength on various inter-set rest interval lengths and the ability to sustain power output during the bench press throw. Additionally, data was gathered on rate of perceived exertions (RPE), delayed onset muscle soreness (DOMS), peak power (PP) and lactate concentration for all participants. The findings suggest that strength should be considered when planning rest intervals during power training.

Caption: Dr. Brookbush instruct Laura DeAngelis on proper form for a Bench Press

Brent Brookbush teaches the proper technique for the bench press.

Study Summary

Study Design	Within-subjects Design
Level of Evidence	IIB evidence from at least one controlled study without randomization
Subject Characteristics	Age +/- Standard Deviation (in years): Stronger Females = 22.3 +/- 5.3, Weaker Females = 22.4 ± 2.6; Stronger Males = 25 +/- 6.5, Weaker Males = 23.8 +/- 1.6 Gender: 9 Stronger Females, 12 Weaker Females, 9 Stronger Males, 9 Weaker Males Physically active Inclusion Criteria: 12 months strength training experience Currently strength training 2 days/week Exclusion Criteria: Cardiovascular disease Physiological disorders Illnesses that may increase risk associated with participation
Methodology	Subjects attended 4 training sessions in a 4-week period. Baseline 1RM for the bench press was measured during the first training session according to the NSCA protocol (4). Subjects were placed into groups based on their performance: stronger females, weaker females; stronger males, weaker males. Training sessions 2-4 followed the same protocol: a warm-up of 2 sets x 10 reps at 50% of 1RM, followed by a 3-minute rest, and then 5 sets x 8 repetitions of the bench press throw using 40% of 1RM, but with varied rest intervals (1- 2- or 3- minutes). The bench press throw was done on a Smith Machine. Peak power (PP) output (maximum value of the power-time curve), lactate concentration and rating of perceived exertion (RPE) were measured during each session. Delayed onset muscle soreness (DOMS) was measured 24 hours and 48 hours post session. The same researcher conducted all sessions, and all subjects were scheduled for the same time each week. Subjects were instructed to maintain normal lifestyle habits, diets and hydration status. Subjects were instructed to refrain from anti-inflammatory medications and nutritional supplements. They were also instructed to refrain from caffeine 3 hours before the sessions and from strength training 72 hours before the sessions.
Outcome Measures	Power Output Subjects were instructed to throw the barbell as high as possible while keeping their head, shoulders and trunk on the bench and their feet on the floor. A T-Force System and T-Force Dynamic Measuring System (Ergotech, Spain) were used to calculate kinematic and kinetic data. PP was calculated from: barbell velocity (bar displacement with respect to time), instantaneous acceleration (from the velocity-time data), instantaneous force (force = mass, acceleration + gravity), and instantaneous power output (power = force x velocity). Validity and reliability of this system was previously established (ICC = 0.81 to 0.91; coefficient variation = 3.6%) (5). Lactate Capillary blood samples (25ml) were taken from the ear lobes and analyzed with a portable device (Lactate Scout; Senselab, Leipzig, Germany). Samples were collected 1 minute pre- and 1 minute post- training sessions. RPE The Borg scale (0-10) was used to measure the physical strain experienced by the subjects. This helped localize upper body perceived exertion. The scale was explained to the subjects prior to the experiment, and they were asked for their rating after the last set of each exercise. DOMS No muscle soreness was reported before the start of each training session. Subjects were asked "How painful do your muscles feel?" and answered with a rating scale from 0 (no pain) to 10 (a lot of pain). This was asked 24 and 48 hours post-session.
Results	Repeated measures ANOVA was used for inter-set PP (P<0.05). Weaker Males Lower PP with 1-minute rest interval in sets 2-5 than with 2-minute and 3-minute intervals Lower PP with 2-minute rest intervals in sets 2 and 3 than with 3-minute intervals Stronger Males Lower PP with 1- minute rest intervals in sets 2-4 than with 3-minute intervals Lower PP with 1-minute rest intervals in sets 3 and 4 than with 2-minute intervals No difference between sets with 2 -minute and 3-minute intervals Weaker Females Lower PP with 1-minute rest intervals in sets 2-5 than with 3-minute intervals Stronger Females Lower PP with 1-minute rest intervals in set 5 than with 3-minute intervals Within Groups Weaker Males: Lower power output in second set with 1-minute rest intervals, lower power output in sets 3-5 with 1-minute and 2-minute intervals, and no significant differences with 3-minute intervals Stronger Males: Lower power output in sets 2-5 with 1-minute rest intervals, no significant differences over the 5 sets with 2-minute and 3-minute intervals Weaker Females: Lower power output in sets 2-5 with 1-minute rest intervals, lower power output in sets 4 and 5 with 2-minute and 3-minute intervals Stronger Females: Lower power output in sets 2 and 5 with 1-minute rest intervals, no significant differences with 2-minute and 3-minute intervals Repeated measures ANOVA was used for intra-set PP (P<0.05). 1-minute recovery All groups showed reduced PP as repetitions increased across all sets (1-5). 2-minute recovery Both weaker groups showed reduced PP during first repetition across all sets. Stronger female and stronger male groups showed reduced PP during fifth and sixth repetitions, respectively, across all sets. 3-minute recovery Weaker female and weaker male groups showed reduced PP in the first and second repetitions, respectively, across all sets. Stronger male group showed reduced PP in the second and last repetition in the set. Stronger female group showed no differences. A single-way ANOVA was used for lactate, RPE, and DOMS for each rest interval (P<0.05). Lactate No differences between weaker males and stronger males Weaker Females: greater lactate with 2-minute and 3-minute rest intervals than stronger females Within Groups: greater lactate with 1-minute rest intervals than with 2-minute and 3-minute intervals Weaker Males: greater lactate with 2-minute rest intervals than with 3-minute rest intervals RPE Increased RPE in both male groups and in weaker Females between 1-minute rest intervals and 3-minute intervals Increased RPE in both weaker groups between 1-minute rest intervals and 3-minute intervals DOMS 24 hours post: greater in weaker males with 1-minute rest intervals than with 3-minute intervals; greater in stronger females with 2-minute rest intervals than with 3-minute intervals 48 hours post: greater in weaker males with 1-minute rest intervals than with 3-minute intervals; greater in weaker females with 3-minute intervals than in stronger females
Our Conclusions	Stronger males and females maintained PP with 2-minute and 3-minute rest intervals. Weaker males and females required at least 3-minute rest intervals. This may imply that strength training phases should precede power training phases (as recommended by the Brookbush Institute), and that strength training may be beneficial for recovery from anaerobic activity. Further the results from this study also suggest that “subjective data”, including RPE and DOMS, was less reliable than objective data, including PP for determining inter-set rest intervals.
Researchers' Conclusions	Subjects' strength levels influence the rest interval required to maintain power output. Stronger males and females maintained PP with 2-minute and 3-minute rest intervals. Weaker males and females required at least 3-minute rest intervals. Stronger subjects may be able to recover faster and repeat the power output performance. Additionally, PP and lactate were more reliable measurement outcomes than the subjective variables of RPE and DOMS.

Caption: Dr. Brookbush teaches a Sled Push for the development of pushing/chest power

Sled Push for Chest Power

Review & Commentary

This study investigated the influence of strength level on the ability to sustain power output over multiple sets with varied inter-set rest intervals. Additionally, data was gathered on rate of perceived exertions (RPE), delayed onset muscle soreness (DOMS), peak power (PP) and lactate concentration for all participants. The study suggest that 1 minute rest intervals are likely insufficient, 2-minute rest intervals may be sufficient for stronger individuals, and that weaker individuals may need 3 minutes or more between sets. Further, stronger individuals had lower lactate concentrations than weaker individuals.

Methodological Strengths

Standardized procedures and validation tools, supported by prior studies, enhance the reliability and strength of study results.
One researcher conducted all testing sessions, minimizing confounding variables.
Subjects were educated and informed of all tests and questionnaires prior to the study.
Extraneous variables (caffeine, anti-inflammatory medications, supplements) were controlled. Subjects were instructed to maintain normal lifestyle habits, diets and hydration. Strength training was also restricted 72 hours prior to the sessions.
Groups were formed based on statistical measures (10% difference in peak power among the subjects of each group)
Subjects represented a broad demographic, increasing the generalizability of the results.

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

Upper body power output was measured using a Smith Machine, which makes the results difficult to generalize. Future studies should utilize other upper body exercises for power measurement, such as the chest pass, soccer throw, or overhead medicine ball throw.
The participants' experience with power exercises was not clear. Differences in power training experience may affect outcome. Future studies should include athletes who have a specified level of power training experience.
The level of strength of each individual or individual group was not correlated with data that could be used in performance enhancement setting. For example, "the weaker group averaged a 1RM bench press of %50 of body-weight (again, only an example)". This would have allowed for groups to be constructed and assigned to appropriate rest intervals in training facilities.

How This Study is Important

The influence of strength on maintaining power output or identifying the appropriate rest interval for subjects' strength levels were not previously investigated. This study's findings allow human movement professionals to make evidence-based decisions regarding optimal rest intervals in power training sessions for individuals of varying levels of strength. Stronger individuals require shorter rest periods to maintain power output during upper body training sessions, which may allow for the necessary volume to continue to make improvement given a fixed session length (e.g. 90 minutes).

How the Findings Apply to Practice

Based on the findings of this study, for upper body power exercise, 2- to 3-minute inter-set rest intervals is optimal for stronger individuals, and inter-set rest intervals of 3-minutes or longer is optimal for weaker individuals. For all subjects, peak power decreased over 5 sets with 1-minute rest periods, resulting in a recommended minimum rest period of 2 minutes. Further, stronger individuals had lower lactate concentration implying that lactate metabolism or a decrease in lactate accumulation may be an adaptation to training, coinciding with relative strength.

How does it relate to Brookbush Institute Content?

The Brookbush Institute encourages practitioners to individualize training programs according to the needs and goals of the client. A range for the inter-set rest interval is commonly selected based on the training phase. This study provides evidence that strength level should also be considered when deciding the amount of inter-set rest that is appropriate, implying the stronger and perhaps those with more training experience, would require less rest. Further, this study may imply that strength training phases should precede power training phases in an attempt to build a base of strength that will enhance power training. Last, the additional data gathered in this study suggests that objective measures like Peak Power (PP) are more reliable than subjective measures like rate of perceived exertion (RPE); implying that speed, height and tempo are better indicators of the end of a set then the clients perception of fatigue or difficulty.

The following videos illustrate exercises related to the bench press throw.

Bench Press

Dumbell Press

Stability Ball Push Ups

Medicine Ball Chest Pass

Power Push Ups

Power Sled Push

Bibliography:

Stone, M., O'Bryant, H., McCoy, L., Coglianese, R., Lehmkuhl, M., & Schilling, B. (2003). Power and maximum strength relationships during performance of dynamic and static weighted jumps. Journal of Strength and Conditioning Research, 17, 140-147.
Ratamess, N., Falvo, M., Mangine, G., Hoffmann, J., & Faigenbaum, A. (2007). The effect of rest interval length on metabolic responses to the bench press exercise. European Journal of Applied Physiology, 100, 1-17.
Nibali, M., Chapman, D., Robergs, R., & Drinkwater, E. (2013). Influence of rest interval duration on muscular power production in the lower-body power profile. Journal of Strength and Conditioning Research, 27, 2723-2729.
Earle, R. & Baechle, T. NSCA's Essentials of Personal Training. Champaign, IL: Human Kinetics, 2004.
Gonzalez-Badillo, J. & Sanchez-Medina, L. (2010). Movement velocity as a measure of load intensity in resistance training. International Journal of Sports Medicine, 31, 347-352.

Questions, comments, and criticisms are welcomed and encouraged -

Influence of Strength Level on the Rest Interval Required During an Upper Body Power Training Session

Research Review: Influence of Strength Level on the Rest Interval Required During an Upper Body Power Training Session

Bibliography:

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