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2003 Physiological Responses Using 2 High-speed Resistance Training Protocols

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This study compared physiological responses to 2 highspeed resistance training (RT) protocols in untrained adults. Both RT protocols included 12 repetitions for the same 6 exercises, only differing in continuous (1 3 12) or discontinuous (2 3 6) mode.
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  334  Journal of Strength and Conditioning Research, 2003, 17(2), 334–337   2003 National Strength & Conditioning Association Physiological Responses Using 2 High-SpeedResistance Training Protocols C ARLA  W ERLANG  C OELHO  , 1 D USAN  H AMAR  , 2 AND C LAUDIO  G IL  S OARES DE  A RAU´ JO 1,3 1 Physical Education Graduate Program, Gama Filho University, Rio de Janeiro, Brazil;  2 Institute of SportsSciences, Comenius University, Bratislava, Slovakia;  3 Exercise Medicine Clinics, Clinimex, Rio de Janeiro, Brazil.  ABSTRACT This study compared physiological responses to 2 high-speed resistance training (RT) protocols in untrained adults.Both RT protocols included 12 repetitions for the same 6 ex-ercises, only differing in continuous (1    12) or discontinu-ous (2    6) mode. For discontinuous mode, there was a 15-second rest interval between sets. We hypothesized that the2  6 protocol was less physiologically demanding than the1    12 protocol. Fifteen untrained adults randomly per-formed the protocols on 2 different days while heart rate(HR), blood lactate (BL), rate of perceived exertion (RPE),and concentric phase mean power (CPMP) were measured.Significantly lower values (mean    SE ) were seen with thediscontinuous protocol for exercise HR (119  5 vs. 124  5 b·min  1 ), BL (5.7  0.5 vs. 6.7  0.3 mMol/L), and RPE (5.4   0.3 vs. 5.8    0.4) (  p    0.05). CPMP tended to be higherin the discontinuous protocol, especially for the 2 last repe-titions. The discontinuous protocol was significantly lessphysiologically demanding, although similar or higherCPMP values were obtained. These findings may help fosterlong-term adherence to RT in untrained individuals. How-ever, future studies are needed to compare physiological ad-aptations induced by these 2 RT protocols.  Key Words:  muscle power, heart rate, high-speedstrength training, rate of perceived exertion, blood lac-tate, adherence Reference Data:  Coelho, C.W., D. Hamar, and C.G.S.Arau´jo. Physiological responses using 2 high-speed re-sistance training protocols.  J. Strength Cond. Res. 17(2):334–337. 2003. Introduction I n recent years, interest in physical activity, both aer-obic and resistance exercises (18), has been growing.Various researchers have postulated that resistancetraining (RT) is the most effective method available formaintaining and increasing lean body mass, increas-ing muscular strength, and gaining power (5, 14–16,19, 22). However, approximately half of the individualswho begin a physical activity program drop out with-in the first weeks (3, 4). Glass and Chvala (6) sug-gested that for aerobic exercise, adherence could be im-proved by allowing the participant more freedom tochoose the type of activity. No data have been availableon different protocols or formats of RT in untrainedindividuals and their impact on adherence to resis-tance exercise programs. However, issues of exerciseadherence are almost as important as functional gainsand health benefits.Training specificity and results may also favorablyaffect long-term exercise adherence (6, 7); thus, adher-ence will be favored if untrained subjects perceive ex-ercise as less demanding, especially at the beginning.There are many RT formats, differing in number of sets or repetitions and in magnitude of loads (13).However, few RT studies have controlled the speedduring the concentric phase to optimize training re-sponses (8–10, 17). Jones et al. (8) concluded that heavi-er training loads and high speed during concentricphase resulted in higher gains of 1 repetition maxi-mum (1RM) in moderately trained subjects. The re-sults of Keeler et al. (9) support the role of high-speedexecution during RT. However, studies comparingphysiological responses to different set and repetitioncombinations by untrained individuals for high-speedRT are lacking.Our purpose was to compare 2 formats of high-speed RT, a discontinuous protocol and a continuousprotocol, using the same number of repetitions andidentical weights with untrained subjects. We hypoth-esized that the discontinuous protocol induces lesspronounced physiological responses while maintain-ing similar power outputs. Methods Experimental Approach to the Problem  A single group of untrained subjects performed 2 dif-ferent RT protocols, each including 12 repetitions of 6different exercises performed always in the same or-  Acute Responses to 2 High-Speed Training Protocols  335 Figure 1.  Typical curve obtained for power load and ve-locity load. Asterisk denotes the maximum power in thecurve. All repetitions were performed as fast as possible. der: (a) rear lat pull-down, (b) seated chest press, (c)knee extension, (d) standing upright row, (e) tricepspress-down, and (f) knee flexion. A metronome wasset up at 20 strokes per minute, allowing careful con-trol of time for repetitions, i.e., 1 repetition every 3seconds. Two minutes of rest was allowed betweeneach exercise. The only difference between protocolswas presence or absence of a 15-second interval afterthe sixth repetition. For the continuous RT protocol,the subjects performed 1 set of 12 repetitions (1  12),whereas for the discontinuous protocol they per-formed 2 sets of 6 repetitions (2    6) separated by a15-second interval. Subjects visited the laboratory 3times, with at least 24 hours between visits. On thefirst visit, PAR-Q responses (1, 20), and baseline mea-surements of body weight, height, resting blood pres-sure, and heart rate (HR) were obtained. To determinemaximal power training loads for each of the 6 exer-cises, power-load curves were obtained. On the next 2visits, on days 2 and 3, subjects randomly performedthe 2 RT protocols, 1    12 and 2    6, at high speed,i.e., as fast as possible, in the concentric phase of move-ment using the loads previously selected. During theexercise session, the following physiological variableswere measured: (a) blood lactate (BLC, Accusport,Winston-Salem, NC) before and 3 minutes after thelast exercise from blood obtained by puncture of themiddle finger; (b) HR (Polar NV, Kempele, Finland) at5-second intervals starting 3 minutes before and end-ing after the final exercise; (c) rate of perceived exer-tion (RPE) using the Borg 0–10 scale (2) after each ex-ercise; (d) concentric phase mean power (CPMP) mea-sured in watts in all repetitions by Fitrodyne (Fi-TRONiC, Bratislava, Slovakia). Subjects  Fifteen presumably healthy volunteers (9 men and 6women) 28    6 years of age (mean    SD ), 170    8cm tall, and weighing 65    15 kg participated in thisstudy. All were untrained, and all signed an appro-priate informed consent form before participating.None of them were taking medications or had mus-culoskeletal disorders that could interfere with the re-sults. The study was approved by our institutional re-view board and complied with national and interna-tional standards for research in humans. Testing Procedures  Exercises were performed with a conventional single-pulley exercise machine with 5-kg weight stacks at-tached to a Fitrodyne dynamometer. Testing included2 attempts at progressively heavier loads, using max-imum speed in concentric phase of each repetition, un-til the load that produced maximum power was iden-tified (Figure 1). This testing protocol was determinedto be highly reliable in a previous study (21).Fitrodyne dynamometers allow calculation of pow-er in watts by multiplying mean gravitational force of the load lifted (previously keyed into the unit by theevaluator) and concentric phase mean velocity (mea-sured by the device). CPMP values for each repetitionat a given load were recorded. Statistical Analyses  Data were summarized as mean    SD  for descriptivestatistics and mean    SEM  for inferential statistics.HR, BLC, RPE, and CPMP (in the 12 repetitions) werecompared between protocols using paired  t -tests. A 2-way analysis of variance (ANOVA) was followed whenappropriate by a Bonferroni  t -test to compare CPMPamong repetitions. A 5% level of probability was con-sidered significant. Results Maximum power and corresponding load results, re-spectively, in the first visit for the 6 exercises were 244   113 W and 31    12 kg for rear lat pull-down, 198   105 W and 28    11 kg for seated chest press, 258   96 W and 33    9 kg for knee extension, 176    88W and 22    9 kg for standing upright row, 136    69W and 17    7 kg for standing upright row, and 90  39 W and 13    5 kg for standing upright row.Although resting HR values were similar (87  14and 85    15 b·min  1 , respectively) for the 1  12 andthe 2    6 protocols, mean HR values at the end of exercise session were minimally higher for the contin-uous than for the discontinuous protocol (125    5 vs.119  5 b·min  1 ;  p  0.05). Resting BLC did not differ between the 2 visits (  p  0.05). However, BLC and RPEvalues were slightly but significantly lower 3 minutesafter the 2  6 protocol (5.7  0.4 and 5.5  0.4 mMol/L) than they were after the 1  12 protocol (6.7  0.5and 5.9    0.4 mMol/L) (  p    0.05).MPCP values for the 12 repetitions were almostidentical for the 2 protocols except for knee extension,which had 5% higher values in the discontinuous pro-  336 Coelho, Hamar, and Arau´jo Table 1.  Mean ( SEM ) power values (in watts) for 6 exer-cises and 2 protocols: 1    12 and 2    6 repetitions.ExerciseProtocol1    12 2    6Rear lat pull-downSeated chest pressKnee extensionStanding upright rowTriceps press-downKnee flexion193 (3.0)158 (3.4)225 (3.0)*159 (3.8)132 (2.3)96 (1.1)193 (3.8)160 (2.5)237 (3.4)*160 (2.2)129 (1.9)94 (0.5)*  p    0.05. Figure 2.  Mean power values in each repetition for kneeextension in both protocols. Asterisks denote significantdifferences for the same repetition in the 2 protocols (  p   0.05). tocol (  p    0.05) (Table 1). Looking at knee extensionrepetitions results, it was possible to identify clearlythat for most of the repetitions, the 2    6 protocolprovided significantly higher scores (  p  0.05) (Figure2). For almost all of the exercises, there was a small but sometimes significant trend toward lower MPCPvalues near the end of set, particularly in the last 2repetitions for the 1    12 protocol. Discussion The merits of high-speed RT have been endorsed re-cently by a position stand of the American College of Sports Medicine (11). This document also mentionsthat high-velocity RT may provide specific benefits indifferent settings and for distinct populations, even el-derly individuals. Several studies have favored high-speed training. For example, Tesch (22) reported thatthe fast-twitch muscular fibers are only engaged whenthe action is performed with sudden and vigorousforce. This finding was corroborated by Koch (10), whosuggested the use of load-contrast training to activateprimarily these fibers and to increase muscle power.Pipes and Wilmore (17) reported that isokinetic RTwith rapid contraction resulted in larger improve-ments in muscle strength and motor performance re-sults than did slow-contraction isokinetic RT. Based onthis assumption, we used high-speed repetitions towork at the maximum level of the power-load curve.No injuries or deleterious effects occurred during orthe day following these exercises, suggesting that evenfor untrained subjects this type of training seems to be safe.For the rear lat pull-down, knee extension, standingupright row, and knee flexion, MPCP values duringthe 1    12 and the 2    6 protocols were different forthe last 2 repetitions. Because all repetitions were vid-eotaped, review of the tapes revealed that the qualityof execution for the 11th and 12th repetitions per-formed declined when there was no break after thesixth repetition. This information may be importantfor evaluating injuries prevention issues during RT.In the triceps press-down exercise, there were largeCPMP variations, which may be due to the fact thatthere is no formal body support provided during thisexercise and thus the muscles of the torso can some-times be used to assist in completing the movement.This explanation is supported by findings from theseated chest press exercise, the only exercise showingminimal MCPC variations among the repetitions. Inthis exercise, appropriate torso support maintains ap-propriate body positioning and isolation of the targetmuscle groups, reducing the chances for errors in ex-ecution.The CPMP values for the 12 repetitions as a wholedid not differ between protocols (  p    0.05). The onlyexception was the knee extension exercise, for whichthe 2    6 protocol generated higher power than didthe 1    12 protocol (  p    0.05). For most of the repe-titions, there was significantly higher power duringthe 2    6 protocol, suggesting that the 15-second in-terval may be important in maintaining power (Figure2). Because this type of effort is primarily dependenton alactic anaerobic metabolism, at least a partial re-covery of ATP-CP may have occurred during this restinterval, making it possible to maintain a proportion-ally higher power in the last repetitions (22).HR measurements differed significantly betweenthe 2 protocols. Slightly higher values were found forthe 1  12 than for the 2  6 protocol; however, thesedifferences were quite small and are probably physi-ologically meaningless. However, significant differenc-es in RPE and BLC favoring lower physiological andperceived demands are more likely to be relevant.These data indicate that a 2  6 protocol is physiolog-ically more comfortable, which may enhance long-termadherence in subjects that begin an RT program.So far, no one has demonstrated that a substantialincrease in muscular acidosis induced by an anaerobicglycolysis is needed or even related to the physiolog-ical adaptations resulting from RT. Quite often, lacticacid accumulation has been regarded as the most im-portant cause of skeletal muscle fatigue (23). However,  Acute Responses to 2 High-Speed Training Protocols  337 recent studies on mammalian muscle, reviewed byWesterblad et al. (23), showed little direct effect of ac-idosis on muscle function at physiological tempera-tures. Inorganic phosphate, which increases during fa-tigue because of breakdown of phosphocreatine, ap-pears to be a major cause of muscle fatigue in vivo(23). MacDougall et al. (12) studied the ratio of sub-strate energy to production of lactic acid during the biceps press exercise. Their experiment was performedwith 8 bodybuilders who completed a typical bicepspress training session at 80% of 1RM. Significantlyhigher BLC values were found after 3 sets than after 1set of an equal number of repetitions. Brachial biceps biopsies indicated that phosphocreatine and glycogenstores were diminished 62 and 12% and 50 and 24%,respectively, after 1 set and 3 sets. Their conclusionwas that muscle fatigue was probably caused by phos-phocreatine depletion in the first set and by increasein acidity in subsequent sets.Analyses of the 4 variables in this study of 6 ex-ercises confirmed our initial hypothesis that a 2    6RT protocol is more cost effective than a 1    12 pro-tocol. The discontinuous mode (the 2    6 protocol)results produced similar power outputs (and evenhigher outputs in the last 2 repetitions) while keepingthe physiological demands at lower levels. However, it isnot clear whether this protocol, although producing sim-ilar or slightly higher CPMP values for the same numberof repetitions and loads, will be able to induce identicalor even larger physiological adaptations to RT. Practical Applications These data suggest that splitting a single set of 12 rep-etitions of 6 commonly used resistance exercises into2 sets by inserting a 15-second rest interval and usingthe load in which maximal power was obtained andperforming as fast as possible in the concentric phasesignificantly decreases physiological demands (sup-ported by subjective assessments). The insertion of arest interval may also allow generation of higher pow-er output while keeping proper execution techniques.These data may encourage the use of this approach, 2   6 set or sets, for the increasing number of individ-uals that are adopting RT exercises as part of a com-prehensive exercise program. Preferential use of the 2   6 protocol may positively influence long-term ad-herence, a major goal of health-oriented exercise pro-grams. These 2 RT protocols should be examined fur-ther to compare physiological adaptations induced. References 1. B AILEY , D.A., R.J. S HEPHARD ,  AND  R.L. M IRWALD . Validation of a self-administered home test for cardio-respiratory fitness. Can. J. Appl. Sport Sci.  1:67–78. 1976.2. B ORG , G.A.V. Psychophysical basis of perceived exertion.  Med.Sci. Sports Exerc.  14:377–381. 1982.3. C HAO , D., C.G. F OY ,  AND  D. F ARMER . Exercise adherenceamong older adults: Challenges and strategies.  Control Clin. Tri-als  21:212S–217S. 2000.4. C UNNINGHAM , D.A., P.A. R ECHNITZER , M.E. P EARCE ,  AND  A.P.D ONNER . Determinants of self-selected walking pace acrossages 19 to 66.  J. Gerontol.  37:560–564. 1982.5. D E L ORME , T.L. Restoration of muscle power by heavy resis-tance exercise.  J. Bone Joint Surg.  27:645–667. 1945.6. G LASS , S.C.,  AND  A.M. 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