48

Journal of Strength and Conditioning Research, 2004, 18(1), 48–52q 2004 National Strength & Conditioning Association

MAXIMAL STRENGTH AND POWER ASSESSMENT INNOVICE WEIGHT TRAINERS

JOHN B. CRONIN AND MELANIE E. HENDERSON

Sport Performance Research Centre, Auckland University of Technology, Auckland, New Zealand.

ABSTRACT. Cronin, J., and M. Henderson. Maximal strengthand power assessment in novice weight trainers. J. StrengthCond. Res. 18(1):48–52. 2004.—The purpose of this study was toinvestigate whether changes in maximal strength and poweroutput occurred over time in the absence of strength and powertraining in novice weight trainers. It also investigated whetherdifferences existed between upper- and lower-body assessmentsand unilateral and bilateral assessments. The power output andmaximal strength (1 repetition maximum [1RM]) of 10 male nov-ice subjects were measured on 4 occasions, each assessment 7–10 days apart. The exercises used to measure the upper- andlower-body strength and power outputs were the bench pressand supine squat, respectively. Significant (p , 0.05) changes inunilateral (9.8–16.8%) and bilateral 1RM (6.8–15.0%) legstrength were found, the first assessment being significantly dif-ferent from all other assessments and assessment 2 significantlydifferent from assessment 4. Changes in the upper body (10–13.6%) were also observed. The only significant difference wasbetween assessment 1 and the other testing occasions. No dif-ferences in power output were observed for both the upper andlower body during the study. It would seem that considerablechanges in maximal strength occur rapidly and in the absenceof any formal strength training program in novice weight train-ers.

KEY WORDS. reliability, bench press, squat

INTRODUCTION

Maximal strength is usually defined as theheaviest load that can be lifted for 1 repe-tition maximum (1RM). The test-retest re-liability of 1RM measurements is high (r 50.92–0.98) among experienced male and fe-

male lifters (17). However, the reliability of 1RM mea-surement for novice weight trainers is less clear. Ploutz-Snyder and Giamis (15) found the number of sessionsneeded to achieve ‘‘absolute’’ consistency for a bilateralknee 1RM assessment in female novice athletes differedfor older (8–9 sessions) compared with younger (3–4 ses-sions) subjects. Hakkinen (9) stated that increases inmuscular strength among novice trainers are easily at-tained, with initial increases of 10% or more obtained af-ter only 2 weeks of intense training. Furthermore, it hasbeen suggested that initial strength increases for noviceathletes will occur with almost any training method andwill occur rapidly (8, 9, 16, 22). Such results suggest that1RM strength changes rapidly and as such may be a lessreliable measure of strength changes in novice trainers.Many studies have reported changes in 1RM strength us-ing novice trainers and made conclusions as to the effec-tiveness of their training programs. However, the efficacyof these training programs may in fact be compromisedby the reliability of 1RM as a strength measure and/orthe trainability of the novice subjects.

Currently, there is much interest in the measurement

of power (1). However, whether power is as easilychanged as maximal strength in novice trainers is notwell documented. Given the propensity of research to usenovice trainers to study how various training programsaffect strength and power, it may be useful to investigatethe stability of these strength and power measures. Thepurpose of this study, therefore, is to investigate whetherchanges in maximal strength and power output occurredover time in the absence of strength and power trainingin novice weight trainers. It also investigates whether dif-ferences exist between upper- and lower-body and unilat-eral and bilateral assessments. We hypothesized thatstrength and power measures would not change betweenassessments.

METHODS

Experimental Approach to the Problem

Upper- and lower-body maximal strength (1RM) using abench press and supine squat were determined for eachsubject. Power outputs that used a load of 40% 1RM werealso determined using the same equipment. The samemaximal strength assessment procedures were replicatedfor 3 subsequent testing occasions. Thereafter, the 1RMand power outputs were statistically analyzed.

Subjects

Ten men volunteered to participate in this research. Thesubjects mean 6 SD age and body mass were 21.0 6 2.7years and 78.7 6 13.4 kg, respectively. All subjects wereof an athletic background (rugby, soccer, and hockey play-ers) and had not weight trained 6 months before thestudy and were instructed not to partake in any weighttraining throughout the period of the research. The Hu-man Subject Ethics Committee of the Auckland Univer-sity of Technology approved all the procedures undertak-en, and all subjects signed an informed consent beforeparticipating in the research.

Equipment

Supine Squat Machine. Assessment of leg strength andpower was performed on a supine squat machine (Figure1). The supine squat machine was custom built (FitnessWorks, Auckland, New Zealand) and used a 300-kg, pin-loaded weight stack attached to a sled to assess the sub-jects. A linear transducer (P-80A, Unimeasure, Corvallis,Oregon; average sensitivity, 0.499 mV·V·mm21; linearity,0.05% full scale) was attached to the weight stack andmeasured vertical displacement relative to the groundwith an accuracy of 0.1 cm. These data were sampled at1,000 Hz by a computer-based data acquisition and anal-ysis program.

The supine squat machine was designed to allow nov-

STRENGTH AND POWER IN NOVICE WEIGHT TRAINERS 49

FIGURE 1. Supine squat machine.FIGURE 2. Double-leg 1 repetition maximum (mean 6 SD)during 4 testing occasions. * 5 Significant difference of test 1to tests 2, 3, and 4. ** 5 Test 2 is significantly different totest 4.

ice subjects to perform maximal squats or explosive squatjumps, with the back rigidly supported, thus minimizingthe risk associated with such exercises in an upright po-sition. The sled lay on top of an undercarriage, which en-abled the sled to be pegged every 2 cm, allowing startangles to be standardized according to the height of thesubjects. The reliability (interclass correlation coefficient[ICC] 5 0.958–0.988) of this equipment and protocols formeasuring leg strength and power has been reported pre-viously (5).

Modified Smith Machine. A modified Smith machinewas used to measuring upper-body maximal strength andpower. The Smith machine was instrumented similar tothe supine squat machine in terms of the linear trans-ducer and computer-based acquisition and analysis pro-gram. The reliability (ICC 5 0.85–0.99) of the equipmentand protocols for measuring upper-body strength andpower has also been reported previously (4).

Determination of Strength and Power Output

Subjects performed a standardized warm-up that wasbased on progressively overloading the musculature oneither the supine squat or Smith machine. Body positionand joint angles were standardized, as were the instruc-tions for each testing occasion. Subjects rested for 2–3minutes between each warm-up set during which upper-and lower-body stretches were performed. This warm-upwas also used to familiarize the subjects with the testingequipment and the lifting techniques used to measurestrength and power. Following familiarization, the max-imal strength of the upper and lower body was performedin the following sequence: unilateral lower body 1RM, bi-lateral upper body 1RM, and bilateral lower body 1RM.To establish each subject’s 1RM, a single repetition tofailure protocol was used (10). A recovery period of 3 min-utes between each repetition was used, and if the 1RMwas not established within 6 attempts, the subject wasinvited to return to complete their assessment (1). Afteradequate recovery, bilateral power outputs for the upperand lower body were measured on the Smith and supinesquat machine, respectively. Subjects were asked to movethe sled or the bar as ‘‘explosively’’ as possible. A load of40% 1RM was used, because loading of this approximateintensity is thought to maximize the mechanical poweroutput of muscle (12–14). This loading allowed projectionof the bar or the sled (ballistic technique), and thereforethe acceleration and deceleration profiles associated withthis type of movement offered greater movement patternspecificity to everyday activity. The procedures to mea-

sure maximal strength were replicated during the 3 sub-sequent testing occasions, each testing occasion 7–10 daysapart. Power was only assessed in sessions 1 and 4.

Data Analysis

The displacement-time data were filtered using a low-pass Hamming filter with a cutoff frequency of 5 Hz. Thefiltered data were then differentiated using a 5-point de-rivative approximation (Lagrange polynomial fourth de-gree about each point) to determine velocity and accel-eration data. The force data was determined by multiply-ing the mass by the acceleration data. Power was calcu-lated by multiplying the force data by the velocity data.The average of 2 trials was used for analysis. The reli-ability and validity of the measures under considerationhave been reported previously (5, 6).

Statistical Analyses

Paired T-tests were used to determine if velocity, force,and power data changed between sessions 1 and 4. One-way repeated-measures analysis of variance with Bonfer-roni pairwise comparisons that were adjusted for multiplecomparisons were used to determine differences in 1RMbetween the 4 testing occasions. An a level of 0.05 wasused for both statistical procedures.

RESULTS

Figure 2 shows that double-leg maximal strengthchanged over time. Test 2 (6.8%), test 3 (9.9%), and test4 (15.0%) differed significantly (F 5 33.07, p 5 0.000)from test 1. The only other significant difference was be-tween the second and final testing occasions, where an8.5% increase in maximal strength occurred.

The results of the single-leg 1RM assessment weresimilar to the double-leg 1RM assessment. The first test-ing occasion was significantly different (F 5 11.50, p 50.004) from all other testing occasions (Figure 3). A 9.8%increase was observed between testing occasions 1 and 2.Further maximal strength improvement occurred be-tween test 3 (13.8%) and test 4 (16.8%) compared withtest 1. Maximal strength changes between tests 2 and 4were also significantly different.

The significant differences between testing occasion 1and all other testing occasions observed in the lower bodycan also be observed in the upper-body 1RM assessment

50 CRONIN AND HENDERSON

FIGURE 3. Single-leg 1 repetition maximum (mean 6 SD)during 4 testing occasions. * 5 Significant difference of test 1to tests 2, 3, and 4. ** 5 Test 2 is significantly different totest 4.

FIGURE 4. Upper-body 1 repetition maximum (mean 6 SD)during 4 testing occasions. * 5 Significant difference of test 1to tests 2, 3, and 4.

Table 1. Velocity, force, and power outputs as assessed during 2 testing occasions for the bilateral bench press and supine squatassessments.

VariablePretest

mean (SD)Posttest

mean (SD) T-test p value

Lower bodyPeak velocity (m s21)Mean velocity (m s21)Peak force (N)Mean force (N)Peak power (W)Mean power (W)

1.518 (0.21)0.781 (0.27)

1256.5 (290.2)1073.4 (290.2)1546.1 (424.3)727.5 (231.4)

1.513 (0.19)0.694 (0.006)

1259.6 (274.6)1108.7 (234.8)1577.7 (494.2)853.2 (341.4)

0.0940.943

20.15621.27220.59621.020

0.9270.3700.8800.2350.5660.334

Upper bodyPeak velocity (m s21)Mean velocity (m s21)Peak force (N)Mean force (N)Peak power (W)Mean power (W)

1.26 (0.242)0.74 (0.173)

375.1 (69.82)325.9 (68.01)411.8 (80.3)221.1 (37.7)

1.23 (0.225)0.73 (0.160)

372.1 (72.61)331.4 (72.54)383.1 (99.8)221.1 (47.1)

0.6100.4880.854

20.8331.222

20.005

0.5570.6650.4150.4260.2530.996

(Figure 4). Test 1 was found to differ significantly (F 516.5, p 5 0.001) from test 2 (10%), test 3 (13.6%), and test4 (13.6%). However, there was no significance differenceamong any other testing occasions.

In terms of bilateral assessment of the legs, no signif-icant differences were found between testing occasions 1

and 2 in any of the velocity, force, and power measures(Table 1). Similarly, nonsignificant differences were ob-served for the assessment of the upper-body measures.

DISCUSSION

Both unilateral (16.8%) and bilateral (15.0%) 1RM legstrength changed during the study in the absence of anyformal strength training program. Testing occasion 1 wasfound to be significantly different from all other testingoccasions, and testing occasion 2 was found to be signif-icantly different from testing occasion 4 for both unilat-eral and bilateral assessment of the legs. In terms of theupper body, testing occasion 1 was only significantly dif-ferent from all other testing occasions. In the subjects ofthis study, improvement in 1RM strength in the absenceof any formal strength training program may be ex-plained in a number of ways. The methods used in thisstudy may have poor reliability. That is, the familiariza-tion and procedures used for 1RM assessment may nothave had high test-retest reliability. However, thestrength assessment was performed according to pre-scribed procedures (1, 10), and the reliability of these pro-cedures has been reported previously (5, 6). If the tech-niques used to establish 1RM were unreliable, the resultsof a great deal of research in this area would appear ques-tionable.

Assuming reliability is not an issue, other factors,such as the trainability of novice weight trainers, mayexplain the increases in strength. Hakkinen (9) statedthat increases in muscular strength among novice train-ers are easily attained, with initial increases of 10% ormore obtained after only 2 weeks of intense training. Thisstudy found increases of 6.8–10% within 1 week of theinitial assessment, 9.9–13.8% within 2 weeks, and 13.6–16.8% within 3 weeks. These increases were found in theabsence of any formal strength training program. It maybe that the 1RM assessments themselves could be inter-preted as a form of training, and therefore training oncea week moving high loads for 1 or 2 repetitions is enoughof a training stimulus to induce the changes in noviceweight trainers observed in this study. This would sup-port the earlier suggestion that initial strength increasesfor novice trainers will occur with almost any trainingmethod and will occur rapidly (8, 16, 22).

STRENGTH AND POWER IN NOVICE WEIGHT TRAINERS 51

The rapid increase in strength of the novice trainerscan probably be attributed to a number of neural factors.A full treatise of these factors is outside the scope of thisarticle, but the factors that may better explain the resultsof this study will be briefly described. It has been reportedthat normally active individuals find it difficult to elicitmaximum force during a maximum voluntary contraction(7). This difference between voluntary maximum forceand the absolute maximum capacity of the neuromuscu-lar system has been termed the strength deficit. Strengthdeficits of 30–45% have been reported in untrained indi-viduals, whereas the strength deficits in elite athleteshave been calculated to be 5% or less (18, 21). This dis-parity suggests that elite athletes are able to use a great-er proportion of their total strength reserves. It is thoughtthat by continually exposing the muscles to high levels oftension, the sensitivity of inhibitory mechanisms, such asthe Golgi tendon organs, may be reduced through a pro-cess known as disinhibition (20). This process improvesneural drive to the agonist muscle and as such allows theindividual to get closer to the absolute maximum force-producing capacity of muscle. There is no doubt that the1RM assessments produced high tension within the work-ing muscle. Whether the frequency and volume of high-tension loads, however, were sufficient to result in dis-inhibition may be questionable (11).

Another candidate mechanism for explaining the re-sults of this study is an improvement in the coordinationamong the muscles involved in the strength assessment.It has been suggested that a large part of the improve-ment in the ability to lift weights was due to an increasedability to coordinate other muscle groups involved in themovement task (16). This may take the form of improvedsynergistic or fixator contribution or reduced coactivationof the antagonist. It could be that during this study thesubjects ‘‘learned’’ to activate the synergistic and fixatormuscles to better affect changes in total 1RM strength.Coactivation refers to the interaction between agonistand antagonist muscles to produce muscle torque arounda joint. To maximize muscle torque, it is necessary to min-imize the amount of coactivation. Carolan and Cafarelli(3) found that an increase in the strength of the kneeextensors during an 8-week training program was asso-ciated with a marked reduction in the level of coactivationof the knee flexor muscles. Curiously, most of the declinein coactivation was observed in the first week of training.Coactivation appears to be a default strategy used by thenervous system when there is uncertainty about the task(3). Due to the novice status of the subjects, it may beassumed that there is a degree of uncertainty associatedwith the 1RM assessment. Furthermore, the greatestgains in 1RM strength for both upper- and lower-bodyassessments were observed in the first week of this study.Reduced coactivation may partly explain the strengthchanges observed in this study.

In terms of the legs, 1RM strength seemed to be in-creasing throughout the study, whereas the increase inupper-body strength appeared to have plateaued as ob-served in no difference between testing occasions 2–3(13.6%) and 3–4 (13.6%). This difference between the up-per and lower body may be attributed to the size of themusculature involved or the complexity of the lifting tech-nique. It has been suggested that the ability to maximallyactivate muscle varies across muscles (2). It may be thatthe strength deficit was less during the bench press as-

sessment (smaller muscle groups) compared with the su-pine squat assessment. Furthermore, the greater com-plexity (moving entire body plus load) and heavier loadsthat were associated with the supine squat assessmentcould potentially result in greater uncertainty and inhi-bition during this assessment task. Hence, reduced coac-tivation and disinhibition, as discussed previously, couldplay a greater role during the supine squat assessment.Since the supine squat movement is considerably morecomplex and involves substantially greater muscle massto perform the lifting task, it is possible that the ‘‘learn-ing’’ of this task took longer than the more simpler benchpress movement. As a result, there is the potential forgreater fixator and synergistic contribution during thistask over a longer course, hence the results of this study.

Interestingly, there were no significant changes in ve-locity, force, or power between testing occasions for boththe upper- and lower-body assessments. Given the con-siderable increases in maximal strength during the study,one would assume increases in power also, since power isthe product of force and velocity. However, this was notthe case. This could suggest that maximal strength andpower are unrelated; however, research suggests that thisis not the case (19). If the strength testing occasions wereviewed as a training stimulus, it may be that this type oftraining produced adaptations of a single factor (i.e., in-creased strength). According to the principle of specificity,for the power measures to improve moving loads similarto the assessment task would be most beneficial. Anotherpossible explanation for the absence of change in the pow-er results in terms of the maximal strength changes mayinvolve contraction force specificity and movement spec-ificity during the assessment task. Because the loads thatwere used to assess power output were lighter (40% 1RM)and involved throwing of the bar during the bench pressor jumping during the supine squat, the movements as-sociated with the assessment tasks were similar to move-ment patterns used in everyday activity. Assuming great-er familiarity with such movement patterns and a lighterloading intensity, it may be that the influence of inhibi-tion, coactivation, and synergistic-fixator contributionmay be less in such assessment tasks.

PRACTICAL APPLICATIONS

It would seem that considerable changes in maximalstrength occur rapidly and in the absence of any formalstrength training program in novice weight trainers. Thecourse of the changes appears dependent on the size ofthe musculature used and the complexity of the move-ment used in the assessment task. Power assessment us-ing lighter loads appears less variable over time. Thesefindings suggest that determining a maximal strengthvalue for a novice subject is inherently difficult, becausethe strength assessment in itself may serve as a strengthtraining stimulus. Hence, strength assessment for novicesubjects needs to occur over multiple occasions to ensurereliability. Consequently, making conclusions as to the ef-fectiveness of various training programs based on maxi-mal strength changes in novice trainers, without attend-ing to this issue of reliability, seems highly questionable.With this in mind, one should remain cognizant of thelimitations that exist in the interpretation of availableresearch data in this field when novice trainers are usedas subjects.

52 CRONIN AND HENDERSON

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Address correspondence to Dr. John B. Cronin, john.cronin@aut.ac.nz.