Sports Med 2005; 35 (3): 213-234

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 1. Seminal Training Practice and Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 2. Power-Load Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 2.1 Upper Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 2.2 Lower Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 3. Power and Performance: Cross-Sectional Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 3.1 Upper Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 3.2 Lower Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 3.2.1 Cyclic versus Acyclic Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 3.2.2 Absolute versus Relative Power Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 3.2.3 Maximum Power versus Power Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 3.2.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 4. Power and Performance: Training Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 The ability to optimise muscular power output is considered fundamental to Abstract successful performance of many athletic and sporting activities. Consequently, a great deal of research has investigated methods to improve power output and its transference to athletic performance. One issue that makes comparisons between studies difficult is the different modes of dynamometry (isometric, isokinetic and isoinertial) used to measure strength and power. However, it is recognised that isokinetic and isometric assessment bear little resemblance to the accelerative/ decelerative motion implicit in limb movement during resistance training and sporting performance. Furthermore, most people who train to increase power would have limited or no access to isometric and/or isokinetic dynamometry. It is for these reasons and for the sake of brevity that the findings of isoinertial (constant gravitational load) research will provide the focus of much of the discussion in this review. One variable that is considered important in increasing power and performance in explosive tasks such as running and jumping is the training load that maximises 214 Cronin & Sleivert the mechanical power output (Pmax) of muscle. However, there are discrepancies in the research as to which load maximises power output during various resistance exercises and whether training at Pmax improves functional performance is debatable. There is also some evidence suggesting that Pmax is affected by the training status of the individuals; however, other strength variables could quite possibly be of greater importance for improving functional performance. If Pmax is found to be important in improving athletic performance, then each individual’s Pmax needs to be determined and they then train at this load. The predilection of research to train all subjects at one load (e.g. 30% one repetition maximum [1RM]) is fundamentally flawed due to inter-individual Pmax differences, which may be ascribed to factors such as training status (strength level) and the exercise (muscle groups) used. Pmax needs to be constantly monitored and adjusted as research suggests that it is transient. In terms of training studies, experienced subjects should be used, volume equated and the outcome measures clearly defined and measured (i.e. mean power and/or peak power). Sport scientists are urged to formulate research designs that result in meaningful and practical information that assists coaches and strength and conditioning practitioners in the development of their athletes. 1. Seminal Training Practice 1RM. Higher tensions would inhibit the ability of and Research muscles to move quickly, which was thought a fundamental prerequisite of power training. Power can be defined as the amount of work In contrast, some coaches have thought heavier produced per unit time or the product of force and loads are necessary for improved power production. velocity. The development of power and its transferPoprawski[3] compared the strength power results of ence to performance has been the source of interest Edward Sarul, 1983 World Champion in the shotand discussion for years. Initially, coaches and put, to nine well trained shot-putters, which included strength and conditioning practitioners debated the >21m throwers. While Sarul was slightly stronger merits of using various loads for the development of than the group average in the bench press (1.4%), power. From the literature there appeared two snatch (7.9%), power clean (5.3%) and squat schools of thought, one that was Western in origin (7.8%), the major differences occurred in tests of and espoused the use of lighter loads (<50% one speed and power at heavy loads in those respective repetition maximum [1RM]) for improving power exercises. For example, Sarul’s snatch velocity output and athletic performance, whereas Eastern ranged from 4.13% faster at 20kg than the average bloc coaches and trainers proposed that heavier to 22.13% faster at 80kg. Similarly, his squat velocloads (50–70% 1RM) were superior. For example, ity was 2.74% greater at 40kg but 25.71% greater at Counsilman[1] a sport scientist and swimming coach, 140kg. These findings led Poprawski[3] to conclude argued that athletes needed to move light loads at that movement velocities at higher loads (50–70% high speed, as fast movements activated the fast 1RM) were critical determinants of athletic success fibres. Conversely, slow training recruited fibres in athletes and training emphasis should be placed with slow contraction characteristics, which was on moving lighter loads (50% 1RM) quickly, rather thought counter-productive to power training. Simithan just striving to lift more weight. Spassov[4] in a larly, Behm,[2] in discussing the use of surgical discussion of programme design for athletes, stated tubing for a tennis power programme, suggested that that experts believe loads of 50–70% 1RM perthis should be combined with traditional weight formed at a maximal rate, develop explosive power. training incorporating loads of not more than 50%  2005 Adis Data Information BV. All rights reserved. Sports Med 2005; 35 (3) Maximal Power Training and Improving Athletic Performance 215 Verkhoshansky and Lazarev[5] in a discussion of example, Edgerton et al.,[11] discussing the effects of muscle architecture, depicted maximum power outEastern bloc principles for the training of speed and put (Pmax) occurring at a range of isometric forces strength believed also that loads of 50–70% 1RM depending whether the knee extensors (45%), knee were necessary for the development of ‘explosive flexors (59%), plantar flexors (35%) and dorsiflexstrength’. Tidow[6] suggested that heavy loads might ors (53%) were studied. These differences were be equally as effective as light loads for stimulating attributed to different fibre lengths that make deterfast motor unit activity, as the fastest high threshold mination of Pmax difficult, as Pmax is related to fibre units need to be recruited to lift heavy loads. This shortening velocity, which in turn is related to the dichotomy as to which loads (light vs heavy) best number of sarcomeres arranged in series (fibre maximise power development remains topical and is length). In fact, Edgerton et al.[11] concluded that the still the source of much research, but clearly there complication of variable fibre lengths makes any was a dichotomy of opinion between Eastern and conclusion regarding power per unit of muscle Western bloc power training philosophies. weight per muscle group of limited value. It would One approach to solving this dichotomy is to seem some of the previous assumptions made by study the relationship between force and velocity, other authors, based on these research findings, are since power is the product of both these variables. It misplaced. Additionally, it would seem that studyis well known that as load increases, the force output ing the power output of whole muscle in vivo would of muscle in concentric contractions increases with a have greater practical significance to athletes, concomitant decrease in the velocity of shortening. coaches and trainers. The power outputs across a This phenomenon is known as the force-velocity spectrum of loads (power-load spectrum) using dyrelationship of muscle.[7] It is thought that maximum namic multiarticular exercises similar to those used power output is the product of optimum force and during weight training need to be examined, the optimum shortening velocity. For isoinertial conresults of which should give a greater appreciation tractions, it has been suggested that maximum powof the load that maximises mechanical power output er output occurs at approximately 30% of maximum in a functional context. shortening velocity or at approximately 30% of maximum isometric force.[7,8] 2. Power-Load Spectrum Many researchers have endorsed such loading for maximising power output[9,10] citing the research of When studying the power-load relationship, one Edgerton et al.,[11] Faulkner et al.[12] and Kaneko et must be cautious of extrapolating findings from the al.[13] as support for the utilisation of such loads. literature since some research has investigated the However, closer scrutiny of this research leaves one power-load relationship indirectly. That is, the relathinking that such conclusions are somewhat mistionship between load and power has been investileading. For example, Faulkner et al.[12] certainly gated, but the load that maximised power output was reported peak powers at approximately one-third of not reported. For example, using subjects from a maximal shortening velocity; however, they do not weight-training class, Mastropaolo[14] measured state at what relative force peak power output occurs power output across loads of 20–100% 1RM. It was (the reader having to extrapolate this information reported that subjects were tested using a benchfrom the graphs provided). Whether power differs press motion, although the figure depicting the exersignificantly across the power-force spectrum is, cise appears to be a shoulder-press machine. Nonetherefore, unclear. In fact, the power profile of slow theless, power profiles based on this movement are and mixed muscles appears similar across loads of detailed in graphical form and the authors concluded 15–50% maximum isometric force.[12] Furthermore, (without any apparent statistical support) that the whether such findings are applicable to whole musload maximising power output occurred at 40% cle or biarticular movement is questionable. For 1RM. However, loads from 40% to 60% 1RM ap 2005 Adis Data Information BV. All rights reserved. Sports Med 2005; 35 (3) 216 Cronin & Sleivert pear very similar in power output. Making such in table I. In all cases, derivatives of the bench press interpretations without statistical analysis is probhave been used to study the power-load relationship. lematic. As can be observed from table I, the loads reported The findings of another often-cited paper that to optimise Pmax are similar irrespective of subject investigated the power-load relationship[13] also training status, age and the type of bench-press need to be interpreted with caution. In this study, 20 motion used. Most studies report a band in which male subjects were allotted to four training groups Pmax occurs, some research also indicating that based on their maximum isometric strength. They loads either side of this band are not significantly trained their elbow flexors using either isotonic (0%, different.[15,16] It would seem then that the majority 30% or 60%) or isometric (100%) contractions. of research reports loads of 30–70% 1RM as the Peak power of the elbow flexors during concentric intensities that maximise mean and peak power outmuscle actions was observed at intermediate moveput. ment velocities of approximately 30% of maximum Three observations from table I appear noteworshortening velocity and 30% of maximum isometric thy. First, greater power outputs are associated with strength.[13] These authors justifiably chose to exthe professional and semi-professional rugby league amine the effects of three loads on Pmax. However, players, which is no doubt a function of their greater such a design does not mean that 30% 1RM is the body mass, training status (maximal strength) and, load that maximises power output. The load that therefore, greater relative loads used for the calculamaximised power output could be anywhere betion of Pmax. For example, Baker et al.[15] reported tween 30–60% of maximum isometric force, yet mean body mass and 1RM of 92.0 ± 11.1kg and many authors[9,10] continue to cite this study as sup129.7 ± 14.3kg, respectively, whereas Cronin et port for light loads (30%) producing maximal al.[16] reported 89 ± 2.5kg and 86.3 ± 13.7kg, respecmechanical power output. Furthermore, uniarticular tively, for club rugby players. Nonetheless the band motion was examined in this study and untrained of loads that maximised mean power output was subjects were used, which limits generalisability to very similar, although ironically it appears that the athletic populations. Also, maximal mechanical dyPmax of the better trained (greater maximal strength) namic power output was reported based on a perrugby league players occurred at a lower percentage centage of maximal isometric force with no estiof their 1RM. Secondly, it may be that the load that mates of power in relation to the actual dynamic maximises peak power is slightly greater than the exercises used in strength training (e.g. squat and load that maximises mean power output. The findbench press) or the athletic performance itself. It is ings for the lower body (see table II) would certainly quite likely that the force at which Pmax occurs support this contention. Thirdly, and related to the differs, if expressed relative to a dynamic strength first point, it would appear that Pmax may be tranmeasure (% 1RM). Based on these observations, it sient and is affected by the strength status of the seems that the assumption of many authors that a population being studied. Mayhew et al.[17] reported 30% 1RM load maximises power output remains that 12 weeks of weight training increased power at problematic. Investigating the power-load spectrum a fixed absolute load (Pmax increased). Presumably, using dynamic (isoinertial) multiarticular motion as the athletes became stronger, the absolute load would appear to have greater practical significance became lighter and consequently could be lifted to strength and conditioning practitioners and sport with greater speed. Thus, the increase in Pmax from scientists alike. 40% to 50% 1RM was due to a 10% increase in maximal strength. However, this does not seem the 2.1 Upper Body case when relative loads are used. Baker et al.[15] found that the percentage 1RM The upper-body mean and peak power outputs associated with a spectrum of loads can be observed that maximised power output was significantly low 2005 Adis Data Information BV. All rights reserved. Sports Med 2005; 35 (3) M axim al ow er T raning nd Im pving A thletic Prform ance 17  2005 A d is D a ta In fo rm a tio n BV . A ll rig h ts re se ve d . Sp o ts M e d 205; 35 3) Table I. Loads that maximised mean and peak power output for the upper body Study Subjects Power measure Maximum power output Maximum power output (% 1RM or load) (W) [mean ± SD]