cluster training

Cluster Training: A NovelMethod for IntroducingTraining ProgramVariationG. Gregory Haff, PhD, CSCS*D, FNSCA,1 Ryan T. Hobbs,1 Erin E. Haff, MA,2 William A. Sands, PhD,3

Kyle C. Pierce, EdD,4 and Michael H. Stone, PhD, FNSCA5

1West Virginia University, School of Medicine, Morgantown, West Virginia; 2Eberly College of Arts and Sciences, WestVirginia University, Morgantown, West Virginia; 3United States Olympic Committee, Colorado Springs, Colorado;4Louisiana State University Shreveport, Shreveport, Louisiana; 5East Tennessee State University, Johnson City,Tennessee

S U M M A R Y

THE INTRODUCTION OF NOVEL

TRAINING STIMULI PLAYS A

CRUCIAL ROLE IN INDUCING

SPECIFIC TRAINING ADAPTATIONS.

ONE METHOD THAT CAN BE

EMPLOYED TO INTRODUCE A

NOVEL STIMULUS TO THE

TRAINING PROGRAM WHILE

MAXIMIZING THE VELOCITY AND

POWER OUTPUT OF THE TRAINING

EXERCISE IS THE INCLUSION OF

THE CLUSTER SET CONFIGURA-

TION. THE CURRENT REVIEW

PRESENTS THE THEORETICAL AND

RESEARCH FOUNDATION FOR THE

USE OF THE CLUSTER SET IN

PERIODIZED TRAINING PRO-

GRAMS AND OFFERS EXAMPLES

OF PRACTICAL APPLICATIONS

THAT CAN BE USED IN THE

PREPARATION OF ATHLETES IN

A VARIETY OF SPORTS.

INTRODUCTION

One of the key concepts ofperiodization is that programsare designed to introduce ap-

propriate training variation in a logicaland systematic fashion in an attempt tostimulate improvements in some per-formance or physiological outcome.

Training variations are essential be-cause they stimulate recovery andadaptation, the avoidance of overtrain-ing, long-term phase potentiation, andan elevation in performance outcomes(17). Variation can be introduced intoa periodized training program in manyways. Some typical examples of train-ing variations that can be employedwhen designing a periodized programare manipulations of the overall train-ing load, number of sets, number ofrepetitions, set configurations, and theexercises selected. These potentialmethods for introducing training vari-ation allow the strength and condition-ing professional a means for introducingnovel stimuli into the training program.Hodges et al. (10) suggest that theintroduction of novel stimuli allowsa more rapid gain in performance andthat the more familiar the individual iswith the task, the slower the overallgains in performance are. Therefore, itis essential that the strength and con-ditioning professional employs varia-tions in the overall training programdesign in order to maximize the trainingoutcomes. This is especially true foradvanced and elite athletes.

One often overlooked method ofemploying variation to the trainingprogram is the manipulation of the

structure of the set being employed.Traditionally, the configuration of a setrequires the athlete to performeach repe-tition in a continuous fashion where norest is taken in between each repetitionof the set (5,9,22). Recently, an addi-tional type of set configuration termedthe rest-pause set (5) or cluster set(9,21) has been proposed as a way ofaltering the structure of a training set.In this type of set configuration, aninterrepetition rest interval of 10–30seconds is employed between eachrepetition performed (9). The configu-ration of the cluster set can be manipu-lated in several ways that may includeusing variable rest interval durations ormanipulating the resistance used witheach repetition of the cluster setdepending on the purpose or the focusof the current block of training em-ployed in the periodized training pro-gram. There are generally two typesof intensity modification that can beemployed with cluster sets, the un-dulating and the ascending cluster setconfiguration. In the undulating clusterset, the resistance is increased in apyramid type fashion (9), while during

KEYWORDS :

interrepetition rest; rest-pause; setconfiguration; resistance training

� National Strength and Conditioning Association Strength and Conditioning Journal | www.nsca-lift.org 67

the ascending set configuration, theresistance is increased with each suc-cessive repetition. When formulatingthe different methods of manipulatingset configurations, each type of setconfiguration should be considered inregard to the overall training plan.Additionally, the strength and condi-tioning professional should considerthe overall goal of each phase oftraining when attempting to employvarious set configurations.

The purpose of this brief review is todiscuss the theoretical basis for the useof the cluster set configuration, presentscientific evidence that examines theuse of the cluster set, and give practicalexamples of how a cluster set mightbe employed in a periodized trainingprogram.

THEORETICAL BASIS FORCLUSTER SETS

The use of short rest intervals betweenthe individual repetitions of a setshould theoretically result in improvedquality of performance during each ofthe repetitions (9). In 2003, Haff et al. (9)

presented a hypothetical model for theeffects of cluster sets on performance.In this model, it was suggested thatperformance characteristics such aspeak power output, barbell velocity,and displacement would decrease witheach subsequent repetition of a tradi-tional set where no interrepetition restwas used (Fig. 1). The concept of aninterrepetition rest interval or clusterwas suggested as a method for allowingeach repetition of the set to beperformed with the highest quality.Therefore, it was hypothesized that theinclusion of a cluster set configurationin which 15–30 seconds of recoverywould be employed between repeti-tions would allow the individual toexperience partial recovery and thusperform each repetition with a higherpower output, peak barbell velocity,and peak barbell displacement.

When considering the potential of thecluster set configuration for increasingthe individual repetition power, it ispossible that an increase in the averagepower output (Fig. 2) of a training setoccurs (14). The use of a cluster set

paradigm may be beneficial in the de-velopment of power-generating capa-city as it may result in a decreasein repetition-induced fatigue (14,18).When a set is performed in the tra-ditional fashion, it is likely that inter-repetition fatigue may manifest itself asacute fatigue factors associated withinthe neuromuscular system or by theaccumulation of metabolic fatigue in-ducing factors, ultimately resulting ina decrease in repetition power.

Viitasalo and Komi (24) have reportedthat reductions in maximal force–generating capacity, rate of force de-velopment, and rate of relaxation canoccur in as few as 5 to 9 maximal con-tractions. They hypothesized that in-creases in blood lactate were partiallyresponsible for the fatigue-inducedalterations in maximal force–generatingcapacity and selected force-time curvecharacteristics. Hypothetically, the in-clusion of a 15- to 30-second interre-petition rest interval may result in somephosphocreatine (PCr) replenishment,while traditional sets configurationsresult in greater PCr depletion, which

Figure 1. Hypothetical model of peak power responses to traditional, cluster, and undulating cluster set configurations.

VOLUME 30 | NUMBER 1 | FEBRUARY 200868

Cluster Training

ultimately stimulates an increased pro-duction of lactic acid and lactate as theathlete uses more muscle glycogen (9).Some support for this contention canbe gained from the work of Sahlin andRen (19) who reported that maximalcontractions resulted in significant de-creases in both adenosine triphosphate(ATP) and PCr concentrations. De-creases in both ATP and PCr were asso-ciated with significant elevations inlactate concentrations, which corre-sponded to substantial decreases inthe amount of force that can be gener-ated. The addition of 15 seconds ofrecovery resulted in an increase inmaximal force–generating capacity thatcorresponded to;79.76 2.3% of initialcapacity (19). Similarly, when 30 sec-onds of extra recovery was usedbetween 5 maximal cycle ergometersprints, a significant elevation of peakpower–generating capacity and a reduc-tion in lactate formation were noted(26). The elevations in lactate associ-ated with the shortest rest intervals aregenerally associated with negative ef-fects on muscle contraction as a resultof impairments in ATP generation thatresult in changes in contractile character-istics, which ultimately alter performance

outcomes (19). Based on this line ofreasoning, the use of cluster sets mightbe a superior method for enhancingmuscular strength, power, and growth.

While the conceptual model of employ-ing a cluster set configuration appearsto be a sound model for developingmaximal strength, enhancing power-generating capacity, or stimulatinggreater hypertrophy, Lawton et al. (15)suggest that the inclusion of a clusterset–loading paradigm may be mostbeneficial for explosive or ballisticstrength training methods such asthose used in programs that rely onweightlifting movements. Support forthis idea can be found in the work ofRooney et al. (18). Although not allstudies agree (6), Rooney et al. (18)suggested that interrepetition rest in-tervals decrease repetition fatigue, butdo not promote the same level ofstrength gains when compared to tra-ditional set configurations. Addition-ally, it was suggested that traditionalcontinuous repetition paradigms in-crease strength development via anincreased activation of higher thresh-old motor units and production ofmetabolic fatigue-induced muscu-lar adaptations (15,18). Additionally,

Kraemer et al. (13) suggest that lactateproduction favors a hypertrophic re-sponse. Based on this line of reason-ing, the cluster set configuration maybe most useful for the developmentof explosive power and more tradi-tional set configurations may be bettersuited for the development of maximalstrength or stimulating hypertrophicresponses.

When using a cluster set configurationin an attempt to improve power-generating capacity, structuring theset in an undulating fashion may beone method that has the potential tomagnify the adaptive stimulus. The un-dulating set configuration uses a seriesof repetitions performed in a clusterformat in which the resistance ascendsfollowed by a series of lighter efforts (9).For example, in an undulating clusterset of 5 repetitions, the athlete mayperform 3 ascending repetitions (i.e.,85%, 90%, 95% of 1RM) followed by 2descending repetitions performed withlighter intensities (i.e., 90% and 85%).Theoretically, the descending portionof the undulating cluster should resultin a potentiation effect in which greaterpower outputs, barbell velocities, anddisplacements are achieved (Fig. 1).

Figure 2. Hypothetical model of average peak power during a traditional, cluster, and undulating cluster set of 5 repetitions.

Strength and Conditioning Journal | www.nsca-lift.org 69

These potential effects may occur asa result of a postactivation potentiationeffect. Postactivation potentiation is anenhancement of force seen after re-petitive skeletal muscle activation (1).The mechanism behind post activationpotentiation, while not completely un-derstood, appears to be the result of anincreased phosphorylation of myosinregulatory light chains (20) or a neuraleffect in intact muscle (3). Increasedphosphorylation sensitizes the actin-myosin interaction to Ca2+, which leadsto greater force production in skeletalmuscle. Neural effects could includeincreased motor unit synchronization,desensitization of alpha motor neuroninput, and decreased reciprocal inhibi-tion to antagonists. While the undu-lating cluster set may induce apotentiation effect, it should be con-sidered an advanced set modificationand may be best suited for highlytrained individuals. Based on currentliterature, postactivation potentiationcomplexes are most effective whenused by well-trained individuals (3).Therefore, it appears that undulatingcluster sets may have a greater poten-tial for inducing specific training adap-tations when implemented with highlytrained individuals.

Collectively, it appears that, from atheoretical standpoint, the inclusion ofcluster set configurations has the poten-tial to alter the training stimulus andultimately magnify the adaptive re-sponse. By altering the set configuration,the strength and conditioning profes-sional may have the ability to developspecific adaptive responses that mayfavor maximal strength, explosivestrength and power, or muscular growth.

RESEARCH SUPPORT FORCLUSTER SETS

To the authors’ knowledge, there areonly a very few papers that have beenpublished in the peer-reviewed litera-ture that examine cluster sets in eithershort- or long-term training situations(2,4,9,14,15,18). Summaries of the re-search that have been concerned withthe short- and long-term effects ofcluster sets are presented in Tables 1and 2, respectively.

ACUTE RESPONSES TO CLUSTERSET TRAINING

In 2003, Haff et al. (9) examined theeffect of 3 different types of set config-urations consisting of a traditional set,cluster set, and an undulating cluster set.The traditional set and cluster set wereperformed with 5 repetitions at anintensity of 90% and 120% of 1RMpower clean. The undulating sets con-sisted of 5 repetitions performed at anaverage intensity of 90% or 120% of thesubject 1RM power clean. The athleteperformed a repetition at 85%, 90%,100%, 90%, and 85% of the subject’s1RM power clean for an average5-repetition intensity of 90% or a repe-tition 110%, 120%, 140%, 120%, and110% of the subject’s 1RM power cleanfor a 5-repetition average intensity of120%. The interrepetition rest intervalfor each of the cluster sets was set at 30seconds. The 3 different set configura-tions were tested using the clean pullwith 2 intensities of 90% and 120% ofa 1RM power clean. When examiningthe 90% intensity trial, the cluster setexhibited a statistically significant in-crease in average barbell velocities(+8.1%) and a nonstatistically signifi-cant increase in barbell displacement(+5.9%) when compared to the tradi-tional set. While the average peakpower output for the set was notsignificantly different, the cluster setresulted in a 6.8% increase in peakpower when compared to the tradi-tional set. For the 120% of 1RMintensity, a statistically significant in-crease in average peak barbell velocity(+7.9%) and displacement (+2.1%) wasnoted during the cluster set whencompared to the traditional set. Con-versely, the average peak power forboth the cluster sets was not different(20.4%) than the traditional set config-uration. One rationale for the lack ofdifference in power output during the120% intensity cluster sets may bebecause previously it was reported thata 90% intensity is the optimal load forpulling exercises (8,16), thus potentiallyconfounding the power data. Based onthis study, it can be concluded that theuse of a cluster set may result inenhancements in velocity of movement,

displacement of the barbell, and, mostlikely, power-generating capacity.

In order to investigate the effects of setconfigurations on the acute repetitionpower outputs during the bench press,Lawton et al. (15) used 4 different setconfigurations. The 4 sets configura-tions included (a) a traditional set of 6repetitions performed at a 6RM in-tensity with no rest between eachrepetition, (b) a cluster of 6 singlesperformed at a 6RM intensity with20 seconds between each repetition,(c) a cluster of 6 repetitions performedas 3 pairs of doubles with a 6RMintensity and 50-second rest betweeneach pair of doubles, and (d) a clusterof 6 repetitions performed as 2 clustersof triples with a 6RM intensity and100-second rest between each group oftriples. The first major finding of thisproject was that the traditional setresulted in a linear decrease in poweroutput across the repetition range.These findings support the hypothet-ical model previously proposed by Haffet al. (9) (Fig. 1). Similar to the resultspresented by Haff et al. (9), the clustersets resulted in statistically significantgreater individual repetition poweroutput and total power output whencompared to the traditional set config-uration. However, there were nosignificant differences between the 3cluster set configurations with regardto individual repetition power or totalpower output. Lawton et al. (14) con-cluded that the cluster set paradigmmay be very beneficial for explosive orballistic strength exercise. Therefore,this type of set configuration may beuseful to the strength and conditioningprofessional who is using weightliftingexercises such as the power clean,power snatch, or pulling motions.

In another investigation, Denton andCronin (4) examined the kinematic(displacement, velocity, and accelera-tion), kinetic (force impulse, work, andpower), and lactate responses to dif-ferent set configurations. Three loadingschemes were employed in conjunc-tion with the bench press exercise inthis investigation for a targeted total of24 repetitions. The first loading scheme


Cluster Training

used was composed of 4 sets of 6 RMwith a 302-second recovery betweengroupings (traditional = T). The sec-ond set configuration comprised 8 setsof 3 performed with a 6RM load witheach group of 3 separated by 130seconds (cluster 1 = C1). The finalgrouping was identical to the secondwith the exception that every other setwas performed to volitional failure(C2). The results of the study revealedthat the C2 configuration resulted in

significantly greater repetitions (;30)when compared to C1 (;24) and thetraditional (;23.6) set configurations.When examining the mean power out-put, total work and impulse of the setsconfigurations C2 were significantlyhigher than both C1 and T, whichwere not different. The blood lactateresponse for C2 was consistently high-er than both T and C1. The results ofthis investigation suggest that increas-ing the interrepetition rest resulted in

the ability to perform more work ata higher quality.

When examining the acute studies,several key conclusions can be drawnfrom the literature. First, it appears thatcluster set training does allow for acutealteration in the overall training stim-ulus induced by a specific exercise.While more work is needed in thisarea, it appears that these set config-urations are best suited for ballistic

Table 1Acute affects of cluster sets

Author Subjects Setconfigurations

Interrep restinterval (s)

Repetitionsequence

Intensity Exercise Results

Haff et al. (9) 8 male trackathletes

Traditional 0 1 set 5 90/120%* Clean pull Peak velocity

5 maleweightlifters

Cluster 30 1 set 5/1 90/120%* Clean pull C . T

Undulatingcluster

30 1 set 5/1 90/120%* Clean pull

Lawton et al. (15) 12 malebasketball players

Traditional (T) 0 1 set 6 6RM Bench press Peak power

14 male soccerplayers

Cluster(single) (C1)

20 1 set 6/1 6RM Bench press C1 = C2 = C3

Cluster(doubles) (C2)

50 1 set 6/2 6RM Bench press . T

Cluster(triples) (C3)

100 1 set 6/3 6RM Bench press

Denton andCronin (4)

9 resistancetrained males

Traditional(control) (T)

0 4 sets 6 6RM Bench press Repetitions

Cluster 1 (C1) 130 1 set 24/3 6RM Bench press C2 . C1 = T

Cluster 2(every othercluster tofailure) (C2)

130 1 set 24/3 6RM Bench press Mean power

C2 . C1 = T

Work C2 .

C1 = T

Lactate

T . C1

C2 . T & C1

*The percentages used in testing were based on the subjects 1RM in the power clean.5/1 = a set of 5 singles was performed for a total of 5 repetitions; 6/1 = a set of 6 singles was performed for a total of 6 repetitions; 6/2 = a set of 3doubles was performed for a total of 6 repetitions; 6/3 = a set of 2 triples was performed for a total of 6 repetitions; 24/3 = a set of 8 triples wereperformed for a total of 24 repetitions.


power exercises such as those used inweightlifting or exercises such as jumpsquats. Finally, it appears that thecluster set configuration has the po-tential to increase work capacity andallow the athlete to train with a higherexercise quality as indicated by kineticand kinematic variables. It may behypothesized, then, that these acuteresponses might be magnified ormanifested in long-term performance

changes if these techniques are usedin appropriately designed periodizedtraining models.

LONG-TERM RESPONSES TOCLUSTER SET TRAINING

In one of the first studies on the topic,Byrd et al. (2) examined the effects of 10weeks of resistance training with 3different interrepetition rest intervals(zero, 1, and 2 seconds). In this study, it

was determined that the 2 groups thatused rest periods between repetitionswere able to increase their overall workoutput. While the major focus of thisstudy was directed at cardiovascularadaptations, the results are importantdue to the relationship between totalwork and training adaptations. Froboseet al. (7) suggest that the adaptiveresponse that stimulates musculargrowth is more dependent on the

Table 2Chronic effects of cluster set training

Author Subjects Set type Repetitionsequence

(sets 3 reps)

Interrep restinterval (s)

Weeks oftraining

Intensity Results

Byrd et al. (2) 50 untrainedmales

Control (C) — — 10 wk, 3 d/wk 6–10RM \ Physical workcapacity

Traditional (T) 3 3 6–10 0 CL2 = CL1 .T = C

Cluster 1 (CL1) 3 3 6–10 1 \ 1RM benchpress

Cluster 2 (CL2) 3 3 6–10 2 CL2 = CL1 = T . C

\ 1RM leg press

T . CL1

CL 2 . C

Rooneyet al. (18)

18 males Control (C) — — 6 wk, 3 d/wk \ Isometricelbow flexionstrength

24 femalesuntrained

Traditional (T) 10 3 6 0 6RM T = CL . C

Cluster (CL) 6 3 6 0 \ Dynamic elbowflexion strength

10 3 6/1 30

6 3 6/1 30 T . CL . C

Lawtonet al. (14)

12 malebasketballplayers

Traditional (T) 4 3 6 0 6 wk, 3 d/wk 6RM \ Bench presspower

14 malesoccerplayers

Cluster (C) 8 3 3 113 T . C

\ Bench press6RM

T . C


Cluster Training

overall work output or volume load ofthe training session than the extent ofthe load, which appears to stimulategreater neural adaptations. Based onthese findings, the implementation ofthe cluster set appears to allow theathlete to train with a higher intensity,thus magnifying the potential trainingstimulus affecting neural adaptations.Furthermore, this configuration allowsfatigue aftereffects to diminish such thatvolume load can be increased, again,potentially magnifying adaptations.

Rooney et al. (18) also examined theeffects of implementing different setconfigurations across a 6-week trainingprogram on isometric and dynamicmarkers of elbow flexor strength. Sub-jects were divided into 3 groups: (a)a control group that did no training, (b)a traditional set protocol, and (c) acluster set protocol that used a 30-second interrepetition rest interval.Training was conducted 3 days perweekwith intensities and volumes vary-ing between 6 sets of 6RM and 10 setsof 6RM loads. There were no differ-ences between the cluster and tradi-tional set protocols for maximalisometric strength. However, the tra-ditional set configuration resulted in asignificantly greater increase in dy-namic muscular strength than thecluster set protocol. The results of thisstudy suggested that during a 6-weekelbow flexion protocol (18) the clusterset offered no benefit over the tradi-tional paradigm. These results need tobe examined carefully as they may bemisleading in that power output wasnot measured. Lawton et al. (15) havesuggested that cluster set training isbest suited for explosive or ballisticexercises. Therefore, it is not unex-pected that the elbow flexor exercisedid not benefit from the cluster setprotocol. Additionally, the subjectpopulation was relatively untrained,consisting of 18- to 35-year-old malesand females who were only defined asbeing healthy. Plisk and Stone (17) ina recent review on periodization sug-gested the implementation of a clusterset paradigm is best suited for trained orhighly trained individuals. Based on

these contentions, the results of thestudy by Rooney et al. (18) are notunexpected, and the findings may bedifferent if highly trained athletes wereused in conjunction with explosiveexercises performed in a cluster fashion.

To the authors’ knowledge, the onlytraining study that examines the effectsof varying the set structure withathletes was performed by Lawtonet al. (14). In this study, 12 juniorbasketball and 14 junior soccer playerswith a minimum of 6 months of resis-tance training experience were dividedinto 3 training groups. Subjects weredivided into 2 training groups: (a)a traditional set group in which 4 setsof 6 repetitions performed at a 6RMintensity every 260 seconds and (b)a cluster set group of 8 3 3 performedat a 6RM intensity every 113 seconds.Subjects trained the bench press 3 daysper week for 6 weeks with ~24 totalrepetitions for ~13 minutes and 20seconds of exercise. At the completionof the study, the traditional set trainingintervention resulted in significantlygreater power outputs and 6 RMstrength when compared to the clusterset group. Additionally, the traditionalset group resulted in a significantlygreater time under tension, which washypothesized as one of the key reasonswhy the traditional set produced supe-rior results. However, the resultsreported by Lawton et al. (14) mayhave occurred as a result of the trainingprogram intervention used by the tra-ditional group being identical to thetesting protocol used to evaluatechanges in muscular strength as in-dicated by a 6RM. This contentionis supported by data presented byIzquierdo et al. (11) that suggest thatwhen training is conducted using setsto failure, a greater improvement intests of muscular endurance (repeti-tions to failure) is noted. Since Lawtonet al. (14) used a 6RM, which might beconsidered a high-intensity muscularendurance test (25), to evaluate perfor-mance, it would be expected that thetraditional set configuration would re-sult in superior performance gains after6 months of practicing the performance

of a 6RM protocol. If other strengthmeasures were used to assess perfor-mance gains, it is likely that differentresults would have occurred.

Collectively, when considering thebody of knowledge about the use ofcluster sets during long-term training, itappears that cluster sets allow theathlete to achieve higher power out-puts and higher volume loads or workoutputs. There is a paucity of long-term training intervention data lookingat the effects of using the clusterparadigm with explosive or ballisticexercises. However, while the fewstudies currently available suggest thecluster set offers no long-term strengthgain benefit, the strength and condi-tioning professional should considerthe cluster set as a tool that may beuseful in the development of specificathletic traits (9,14). This tool isprobably best suited for ballistic explo-sive exercises and less useful for non-ballistic exercises such as the benchpress. Additionally, the cluster set hasyet to be investigated in the context ofa periodized training program. Furtherresearch is needed in order to definethe most effective time points duringthe periodized training program inwhich the cluster set is most beneficial.

PRACTICAL APPLICATION OFCLUSTER SET

The implementation of cluster sets ina periodized program can be accom-plished in many ways depending onthe specific goals of the phase oftraining. For example, the goals of thehypertrophy phase of training are tostimulate hypertrophy, decrease bodyfat mass, and increase work capacity(23). The traditional set may actuallybe best suited for this phase of trainingfor most exercises, but the goals of thehypertrophy phase of training may alsobe accomplished by employing shorterrest intervals, such as 15 seconds, in thecluster set. The duration of recoverybetween each repetition may dependon the complexity of the exercisein which the cluster set is beingemployed. Based on the contempo-rary literature, it appears that powerexercises such as the power clean or


power snatch might be most affectedby using the cluster paradigm. Forexample, in weightlifting, it has beenargued that performing traditional setswith the complete lifts (i.e., clean,snatches, power cleans, power snatches)using high-repetition schemes results infatigue-induced alterations in techniquethat may result in the development oftechnical deficiencies (9,12). As a resultof this belief, weightlifters generally onlyperform repetition schemes, whichrange between 1 and 5 repetitions perset (12). Conversely, the cluster set may

offer a desirable solution to the volumelimits that are sometimes placed onperforming complete lifts as it results inincreased work tolerance and can helpmaintain or enhance performance out-comes. Table 3 gives an example ofa strength-endurance phase of trainingin which cluster sets could be employedfor the power snatch and power clean,while traditional sets are performedwith less technical exercises such asclean pulls. While the example pre-sented in Table 3 uses 10 singlesperformed as a cluster of singles, one

might also consider performing clustersof 2 repetitions for a total of 10repetitions for the given set. This typeof cluster orientation may actually resultin greater increases in endurance asthere is less recovery between eachrepetition.

When formulating a basic strengthphase of a periodized training program,one of the primary goals is to increasemuscular strength; thus, using a tradi-tional set configuration for nonballisticexercises may be warranted. However,among advanced athletes, the for-ce/power production during ballisticmovements can be augmented usingcluster sets. A shift in the interrepeti-tion rest interval to 30 seconds iswarranted as the overall intensity ofthe cluster should be higher in thisphase of training and a greater amountof recovery may be needed betweeneach repetition of the set. In this phaseof training, the strength and condition-ing professional should consider im-plementing an undulating cluster setconfiguration as it will allow the athleteto begin to use higher lifting intensities.When using the undulating cluster set,the overall intensity of the set is definedas the average kilograms lifted acrossthe set. For example, if the athlete is toperform an undulating cluster set of5 repetitions with an average intensityof 110 kg, the athlete might performlifts at 105, 112.5, 117.5, 112.5, and105 kg for each set. Table 4 presents anexample of a training session in whichthe undulating cluster set it is used.

During a strength/power phase of aperiodized training program, the pri-mary goals are to maintain or increasemuscular strength and improve power-generating capacity (23). This phasemay be the logical time during a perio-dized program to fully use a clusterdesign. In this scenario, for example,the strength and conditioning coachcould implement the undulating clusterset as this set configuration hasa reasonable potential to producepostactivation potentiation effects.Furthermore, the use of a heavy load(mid-cluster) helps to maintain orstimulate strength gains. The use of

Table 3Example cluster set implementation during a hypertrophy phase of

training

ExerciseSets 3

repetitions Set type

IntensityInterrepetitionrest interval (s)kg % 1RM

Power snatch 1 3 10/1 Cluster 90 75 15

Snatch gripshoulder shrugs 3 3 10 Traditional 140 115* 0

Rest 15 min

Power clean 1 3 10/1 Cluster 115 80 15

Clean pull (FL) 3 3 10 Traditional 160 110† 0

Clean grip RDL 3 3 10 Traditional 120 86† 0

Max power snatch = 120 kg; max power clean = 145 kg; RDL = Romanian deadlift.*Based on maximum power snatch.†Based on maximum power clean.

Table 4Example cluster set implementation during a basic strength phase of

training

ExerciseSets 3

repetitions Set type

IntensityInterrepetitionrest interval (s)kg % 1RM

Snatch grip shrugs 3 3 5 Traditional 160 133* 0

Power snatch 3 3 5/1 Undulatingcluster(105, 112.5,117.5, 112.5,105)

110 92* 30

Snatch pull 3 3 5 Traditional 145 120* 0

Snatch grip RDL 3 3 5 Traditional 125 104* 0

Max power snatch = 120 kg; max power clean = 145 kg; RDL = Romanian deadlift.*Based on maximum power snatch.


Cluster Training

a 30- to 45-second rest interval inconjunction with either the undulating(or ascending cluster) may be useful inallowing the athlete enough recoverybetween repetitions so that higherpower outputs are achieved. In theascending cluster set, the athlete wouldprogressively increase the overall in-tensity of the set with each set. Thus,force output could be maximized onthe final repetition. Several differentvariations of ascending clusters couldbe used. For example, the athlete mayperform 3 sets of clusters consisting of3 repetitions with the average intensityof each set being increased (set 1 = 110,115, 120; set 2 = 115, 120, 125; set 3 =120, 125, 130). This method potentiallyemphasizes peak force developmentand may be more suited to partialmovements or power movements (e.g.,power snatch) rather than full weight-lifting movements due to a fatigueeffect using 3 ascending sets in a row.Other configurations could be con-structed potentially emphasizing dif-ferent characteristics. Table 5 presentsan example of a training session usingan ascending cluster set.

CONCLUSIONS

Based on theoretical and actual scientificdata, the cluster set appears to bea unique method for introducing trainingvariation into the periodized trainingprogram. The various methods forimplementing cluster sets offer thestrength and conditioning professionala tool that may be useful when workingwith training and highly trained athletes.

While more research needs to beconducted examining the performanceand physiological affects of the variouscluster set models, current data suggestthat strength and conditioning profes-sionals should consider using this noveltraining stimuli as part of their trainingplans, especially when working withexplosive exercise such as the powerclean, power snatch, and potentiallypulling exercises (clean and snatch).j

Gregory Haff is Assistant Professor inthe Exercise Physiology Division at theWest Virginia University School ofMedicine in Morgantown, West Virginia.

Ryan Hobbs is a graduate assistant inthe Exercise Physiology Division at theWest Virginia University School ofMedicine in Morgantown, West Virginia.

Erin Haff is a graduate assistant in theEberly College of Arts and Sciences, atWest Virginia University, Morgantown,West Virginia.

William Sands is Head of SportsBiomechanics and Engineering for theUnited States Olympic Committee,Colorado Springs, Colorado.

Kyle Pierce is Professor in theKinesiology and Health ScienceDepartment and is the Director and Coachof the USA Weightlifting DevelopmentCenter at Louisiana State University inShreveport, Louisiana.

Michael Stone is Director of theExercise and Sports Science Laboratoryin the Department of Kinesiology, Leisure,and Sport Science at East Tennessee StateUniversity, Johnson City, Tennessee.

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Table 5Example cluster set implementation during a strength/power phase of

training

Exercise Sets 3

repetitionsSet type Intensity

(kg)Interrepetitionrest interval (s)

Speed squats 3 3 3 Traditional 90 0

Power clean 1 3 3/1 Ascending cluster 110, 115, 120 30

1 3 3/1 Ascending cluster 115, 120, 125 30

1 3 3/1 Ascending cluster 120, 125, 130 30

Push jerk 3 3 3 Traditional 120 0

Based on max back squat = 180 kg; max power clean = 140 kg; max push jerk = 135 kg.


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Cluster Training

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