Throwing Performance is Associated with Muscular Power

Transcription

1 Training & Testing 505 Throwing Performance is Associated with Muscular Power Authors M. Bourdin 1, O. Rambaud 1, S. Dorel 2, J.-R. Lacour 1, B. Moyen 1, 3, A. Rahmani 4 Affiliations 1 Universit é de Lyon, Universit é Lyon 1, INRETS, LBMC, UMR_T 9406, Oullins, France 2 INSEP, Laboratoire de biom é canique et de physiologie, Paris, France 3 Hospices Civils de Lyon, Service de Chirurgie Orthop é dique, Pierre-B é nite, France 4 Universit é du Maine, Laboratoire Motricit é, Interaction, Performance, EA 4334, Le Mans, France Key words force-velocity relationship bench press half squat guided barbell s tiffness Abstract The aim of the present study was to test the hypothesis that performance in throwing events is associated with muscular characteristics of both upper and lower limbs. Thirty-eight male throwers volunteered to participate. Bench press and half squat tests were conducted on a guided barbell. The barbell displacement signal was recorded using a kinematic system. Maximal power, corresponding optimal velocity and force (P max S, VoptS, Fopt S and P max BP, VoptBP, FoptBP for half squat and bench press, respectively) were extrapolated from the power-velocity relationship. Lower limb stiffness (K) was determined during maximal hopping. The results demonstrated that P max S and P max BP were correlated with each thrower s season s best performance (SBP, r = 0.54, p < 0.01 and r = 0.71,, respectively). P max S expressed relative to body mass was not correlated with SBP. K was significantly correlated with SBP ( r = 0.66, ). The relationship between P max BP expressed relative to body mass and SBP remained significant ( r = 0.54, ). The results of the study suggest that high strength and stiffness values for lower limbs and strength and velocity characteristics for upper limbs may be associated with athletic throwing performance. accepted after revision February 12, 2010 Bibliography DOI /s Published online: April 23, 2010 Int J Sports Med 2010; 31: Georg Thieme Verlag KG Stuttgart New York ISSN Correspondence Dr. Muriel Bourdin Laboratoire de Biomécanique et Mécanique des Chocs Facult é Lyon-Sud Charles M é rieux, BP Oullins CEDEX France Tel.: + 33 /47 / Fax: + 33 / 47 / Muriel.Bourdin@univ-lyon1.fr Introduction Maximal power output (P max ), integrating force and velocity qualities, is generally associated with explosive event performance. However, studies devoted to this topic are scarce and most adress sprinting. For instance, lower limb P max determined during an 8 s maximal treadmill sprint has been related to the acceleration phase of sprint running (40 m time) [6]. Likewise, lower limb P max determined during sprint cycling was related to 200 m track cycling performance [8]. Young et al. [29] demonstrated that the single best performance of starting performance (2.5 m time) was the peak force (relative to body mass) generated during a jump. Athletic throws involve the entire body. Lower limbs initiate the movement and the sequence is finished by trunk and upper limb action. The release velocity of the implement is the main determinant of athletic throwing performance [1]. It depends on the ability to accelerate maximally and quickly the system thrower plus implement. Athletic throwing performance analysis requires assessing both lower and upper limb muscular abilities. To the best of our knowledge, few studies have been devoted to this. It has been demonstrated that both the muscle maximal isokinetic torque and the force of dominant elbowextensor determined during iso-inertial bench press test were significantly related with performance in a population of novice shotputters [21]. Terzis et al. [22] demonstrated a significant relationship between half squat and inclined bench press maximal strength (1 RM) and performance in national level shotputters. A recent study showed that P max determined for upper and lower limbs during arm cranking and leg cycling were significantly related to performance in a group of national level male javelin throwers [4]. However, the javelin throw differs from others in that a run-up from 25 to 30 m is done before final javelin release and lasts approximately 5 s. Duration for other throws (discus, hammer and shotput) is less than 3 s. It could be supposed that the ability to reach quickly high force levels is crucial in both situations. Isometric [15, 25, 26] and concentric rate of force development [25, 26] has been related to lower limb musculotendinous stiffness (K). Accordingly,

2 506 Training & Testing for a purely concentric movement, the stiffer subjects initially possessed a greater rate of power production [27] that is to say a greater acceleration. This is of particular importance when high velocity should be reached rapidly. In agreement with this hypothesis, K determined during hopping has been related to performance during a 40 m sprint [6] and to acceleration during the first part of a 100 m sprint [5]. To our knowledge, relationship between lower limb stiffness and throwing performance has never been explored. Previous studies of Terzis et al. [21, 22] demonstrated that upper and lower limb maximal strength is associated with shotput performance. Nevertheless, power and velocity characteristics of upper and lower limbs as well as lower limb stiffness should also influence throwing performance. This analysis of muscular characteristics could be of great importance for the optimal development of training programs. The aim of the present study was to test the hypothesis that throwing performance is correlated with muscular power-velocity characteristics of the upper and lower limbs in a group constituted of highly trained throwers from different specialties (discus, hammer and shotput). Methods Subjects Thirty-eight national male throwers volunteered to participate in this study. They were discus throwers (DT, n = 14), hammer throwers (HT, n = 13) and shotputters (SP, n = 11). The season s best performance (SBP) of each athlete was collected and expressed relative to the current world record corresponding to each event (SBP expressed as % ). Anthropometric values and SBP relative to each group are listed in Table 1. This study was performed at the end of the winter period of training, which corresponded to the beginning of the competitive season. Subjects were instructed to avoid weight training the day before laboratory testing. Before giving their informed consent, they were informed carefully about the experimental procedures. The study has been performed in accordance with the ethical standards of the International Journal of Sports Medicine [9] and approved by the Consultative Committee for the Protection of the Person into the Biomedical Research of the Centre Leon B é rard in Lyon (France). Because 7 subjects did not perform the squat test, statistical analysis concerning this exercise was done on 31 subjects only (13 DT, 8 HT and 10 SP). Thirty-seven subjects did the stiffness test, one of them could not because of an Achilles tendon injury. Procedures The general outline of the tests started with a warm-up including several submaximal repetitions of the exercise performed at Table 1 Anthropometric characteristics and performance level (SBP) expressed relative to the respective world record of the whole group and each specialty (discus throwers, DT; hammer throwers, HT; and shotputters, SP). Whole group DT HT SP age (years) 22.9 ± ± ± ± 5.5 height (m) 1.86 ± ± ± ± 5.8 body mass (kg) 99.4 ± ± ± ± 23.7 SBP ( % WR) 64.7 ± ± ± ± 7.4 the beginning of each test. During the first session, the subjects started with the half squat test using a guided barbell. After a min rest period, the bench press test was done. Subjects performed 2 trials at each load. Last, after a 15 min rest, 3 trials of a 5 s series of maximal bounces on a resistive mat were performed to determine lower limb stiffness. Each trial (for half squat, bench press or maximal bounces) was followed by a rest period of at least 3 min. It has previously been demonstrated that for half squat [18] and bench press exercise [19] P max was measured for the lightest loads. For coaches and athletes, an evaluation protocol must be carried out as quickly as possible, especially during training camp. A compromise therefore was to use the same absolute load (the lightest one corresponding to the laboratory guided barbell mass without any load). Half squat Shoulders were in contact with the bar and the starting knee angle was about 90 [12, 16 18]. This angle was checked with a medical goniometer (Comed, France). Mechanical stops were positioned below the bar to ensure the repeatability of appropriate lower limb positions. On command, the subject performed a concentric all-out leg extension starting from the flexed position against increasing loads (24, 34, 44, 74, 104, 134 and 164 kg). Subjects were instructed to perform the exercise as fast as they could. Therefore, for the lightest loads, the subjects took off from the ground. The barbell was maintained in contact with the shoulders voluntarily throughout the motion. Bench Press Upper-limb force was assessed on a series of bench-press movements made against increasing loads (24, 34, 44, 54, 64, 74 and 84 kg). Subjects were supine on the bench. The barbell was positioned above the pectoralis major, supported by the lower mechanical stops of the measurement device. At the start of the movement, the shoulders were in contact with the bench. The subjects held the barbell at shoulder-width, with an initial elbow angle of 90 between upper arm and forearm [12, 21], checked with a medical goniometer (Comed, France). Subjects could regain this position throughout the test session by using markers on the barbell. On a verbal order, the subject performed an explosive upper limb extension without countermovement. The barbell had to stay in the subject s hands throughout the movement and not to be thrown. Rebound test To calculate lower limb stiffness, the throwers were instructed to hop maximally on a resistive mat (Ergojump ), keeping their legs as straight as possible and their hands on their hips. Data analysis Guided barbell Because parts of the measurements were made in different training camps, half-squat and bench-press tests were conducted on three different horizontal guided barbells (Multipower Basic, Panatta Sport, Apiro, Italy; Kettler Smith machine, Ense- Parsit, Germany and a modified Smith machine, Weider Fitness, Salt Lake City, UT, USA). Whatever the barbell used, the displacement signal was recorded by a kinematic system [3, 16], consisting of two infrared photo interrupters locked in a shuttle gliding on a track bar and fixed onto the barbell. The optical encoder was placed facing an optical code strip, stuck to the track bar, com-

3 Training & Testing 507 posed of slots 0.75 mm apart. The optical encoder counted the slots as it passed them and recorded each 0.75 mm displacement as the barbell moved. Displacement could be recorded over a maximum distance of mm and at a minimum speed of m.s. The displacement signal was sampled at 200 Hz and stored on a computer via an electronic interface card equipped with a 12-bit counter (Hewlett Packard, type HCTL-2000, Palo Alto, CA, USA). The signals were filtered digitally using a 12 Hz low-pass Butterworth filter with zero phase lag. According to the method proposed by Bosco et al. [3] and validated by Rahamni et al. [16], customized software was used to calculate the instantaneous velocity and acceleration from successive displacement time-derivatives for each lift. Instantaneous force produced by the subject (F, in N) in the concentric phase was calculated as: F= M (a+ g) + Ff where M is the moving mass, g is the gravitational acceleration (9.81 m.s 2 ), a is the calculated acceleration of the barbell (m. s 2 ) and F f is the friction force of the guided barbell (determined by a free-fall). F f was determined for each guided barbell used. For the half squat exercises, M corresponded to the body mass added to the additional load [16]. During the bench press exercises, M was equal to the mass of the upper limbs, determined with Winter s anthropometric table [28], added to the additional load [19]. The instantaneous power (in W) was calculated as the product of force and velocity at any given time: for details, see [3]. For each trial, force, velocity and power output were averaged over the period of the concentric phase of the movement (i. e., positive power values). For each load, the best trial i. e., that resulting in the highest average velocity was kept for the analysis. Force-velocity and power-velocity relationships Data were pooled to document the force-velocity and powervelocity relationships, using linear and quadratic regressions, respectively [3, 12, 17, 18]. Maximal power (Pmax ) was identified as the apex of the fitted power-velocity relationship. It was calculated considering that the derivative of the equation of powervelocity relationship is equal to zero at this point. Optimal velocity (V opt ) was the velocity at which P max occurred. The value of force at which P max occurred i. e. optimal force (Fopt ) was deduced from the values of P max and V opt. To avoid information redundancy, maximal velocity and maximal force (extrapolated from the force-velocity relationship) data were not used. P max S, V opt S and F opt S values were obtained from the half squat test analysis and P max BP, Vopt BP and F opt BP were those obtained from the bench press one. Lower limb stiffness Ergojump is a resistive mat (Mayser, type SM /BK, Ulm /Donau, Germany) that provides an on / off signal detecting any foot contact with the ground. This mat is connected with a digital timer (accuracy ± s). The timer is triggered by the subject s release from the ground and is stopped by touchdown. Ground contact time and flight time were recorded during a 5 s series of maximal bounces. According to the method validated by Dalleau et al. [7] the stiffness (K in kn.m ) was calculated as: K N M. π( Tf + Tc ) = Tf + T 2 c T c Tc π 4 a Power (W) b Power (W) r = Velocity (m.s -1 ) r = Velocity (m.s -1 ) Fig. 1 Power-velocity relationships in ( a ) half squat and ( b ) bench press of a typical subject. Where M is the total mass, T c the ground contact time and T f the flight time. The method is fully described in Dalleau et al. [7]. The mean K-value relative to each trial was calculated. The trial showing the highest mean K-value was used. The term relative was used in the analysis when P max, Fopt or K values were expressed relative to body mass. Statistical analysis Analyses were performed using JMP V7.0.1 (SAS Institute, Cary, NC, USA). Data are expressed as the mean ± standard deviation (SD). The coefficient of variation was the SD-to-mean ratio expressed as a percentage. Linear force-velocity and quadratic power-velocity regression models were fitted by the least square method. Simple associations were evaluated using Pearson s correlation coefficient ( r ). The distribution of each variable was examined with the Shapiro-Wilk normality test. As data were not normally distributed, Wilcoxon test was used for data group comparisons. The statistical significance was set at α = Results No significant differences in age, height, body mass or SBP were found between the three groups of throwers ( Table 1 ). Therefore the relationships within the entire group using SBP as the dependent variable were calculated. Force-velocity and power-velocity relationships For the whole group, the force-velocity relationship was significantly described by a linear regression (0.95 < r < 1.00, p < 0.05 and 0.92 < r < 1.00, p < 0.05 for bench press and half squat, respectively) and power-velocity relationship by a second order polynomial model (0.99 < r < 1.00, p < 0.05 and 0.99 < r < 1.00, p < 0.05 for bench press and half squat, respectively). The half squat and bench press power-velocity relationships of a typical athlete are

4 508 Training & Testing a Fig. 2 Relationships between season s best performance (SBP) expressed relative to the respective world record and maximal power (P max ) extrapolated from a ) the half squat test and b ) the bench press test for the whole group and each throwing subgroup. Fig. 3 Relationships between season s best performance (SBP) expressed relative to the respective world record and lower limb stiffness (K) for the whole group and each throwing subgroup. SBP (%WR) Whole group ( ) r = 0.54 p < SP HT DT P max Half Squat (W) SBP (%WR) Whole group ( ) r = SP HT DT b SP HT DT Lower limb stiffness (kn.m -1 ) 85 SBP (%WR) Whole group ( ) r = P max Bench Press (W) DT subgroups. F opt BP for the HT subgroup was significantly lower than in the SP group. K did not vary significantly between the subgroups. The correlation between P max S and SBP was significant for the SP subgroup (r = 0.68, p < 0.05), demonstrated a trend (r = 0.68, p = 0.06) for the HT subgroup and was not significant for the DT subgroup ( Fig. 2a ). K was significantly correlated with SBP for each subgroup (r = 0.64, p < 0.05; r = 0.73, p < 0.01 and r = 0.65, p < 0.05 for DT, HT and SP, respectively, Fig. 3 ). The correlation between P max BP and SBP was significant for each subgroup (r = 0.65, p < 0.05; r = 0.83, and r = 0.91, for DT, HT and SP respectively, Fig. 2b ). illustrated in Fig. 1. The comparison between experimental peak power and P max extrapolated from the relationship demonstrated that an apex was obtained for bench press relationship (735.7 ± vs ± W respectively, NS). In line with a previous study of Rahmani et al. [18] for a half squat test, the difference between experimental peak power and extrapolated P max was significant ( ± vs ± W, respectively, ). In this case the absence of apex causes the P max value to be outside the tested velocity range. Nevertheless, the difference between peak power values measured during the squat protocol and P max extrapolated was lower than 9 %. Thus, the apex was close to experimental data and interindividual variations in P max values thus extrapolated may be interpreted within the context of the present study. Whole group As shown in Fig. 2, PmaxS and P max BP were significantly correlated with SBP ( r = 0.54, p < and r = 0.71,, respectively). Body mass was correlated with SBP ( r = 0.54, ), F opt S and F opt BP (r = 0.91, and r = 0.66,, respectively) and P max S and P max BP ( r = 0.69, and r = 0.62,, respectively). Relative Pmax S was not correlated with SBP. However, the relationship between relative P max BP and SBP remained significant ( r = 0.54, ). Fopt S and F opt BP were significantly correlated with SBP ( r = 0.63, and r = 0.49, p < 0.01, respectively). K was significantly correlated with SBP ( r = 0.66,, Fig. 3 ). K was also correlated with P max S ( r = 0.68, ) and body mass ( r = 0.48, p < 0.01). The relationship between SBP and relative K remained significant ( r = 0.45, p < 0.01). Subgroups Mean values of K, P max, Vopt and F opt for squat and bench press tests for each subgroup are listed in Table 2. Pmax BP and V opt BP for the HT subgroup were significantly lower than in the SP and Discussion The purpose of this study was to investigate whether performance in throwing events (excepted javelin) may be associated with muscular characteristics of both upper and lower limbs. The results demonstrate specific muscular characteristics for lower and upper limbs. For the whole group, SBP was correlated with P max S ( Fig. 2a ) and F opt S. These results were in accordance with brief exercise requirements. The athlete should accelerate quickly from a standing position and high force levels are needed. This analysis is in agreement with a recent study of Terzis et al. [22] who evidenced a positive relationship between 1 RM obtained for squat exercise and shotput performance. The study of Young et al. [29] also demonstrated that the single best predictor of starting performance (2.5 m sprint time) was the peak force generated during a jump. An original finding was that K was correlated with both SBP and P max S for the whole group ( Fig. 3 ). This result is in line with studies demonstrating a significant relationship between short sprint performance and lower limb K determined during hopping [5, 6]. Interestingly and in accordance with Wilson et al. [26, 27], lower limb K was also correlated with P max S. A stiff musculotendinous system appears to enhance the force production capacity by keeping the contractile component in the optimal part of the length-tension relationship and serves to facilitate the initial transmission of force to the skeletal structure [26]. As a result, for a purely concentric movement, stiffer subjects initially possess a greater rate of power production [27]. To summarize, the present results indicate that lower limb maximal force (i. e., large body mass) is an important, but not the only factor performance in athletic throwing. For a given maximal force level stiffer lower limbs, result in a higher performance.

5 Training & Testing 509 Whole group DT HT SP F opt S (N) 1650 ± ± ± ± 287 F opt S (N.kg ) 16.8 ± ± ± ± 1.2 V opt S (m.s ) 1.81 ± ± ± ± 0.28 P max S (W) 2994 ± ± ± ± 721 P max S (W.kg ) 30.4 ± ± ± ± 5.3 F opt BP (N) 583 ± ± ± ± 193 * F opt BP (N.kg ) 5.9 ± ± ± ± 1.2 V opt BP (m.s ) 1.26 ± ± 0.33 ** 1.02 ± ± 0.24 * P max BP (W) 732 ± ± 177 ** 536 ± ± 263 ** P max BP (W.kg ) 7.3 ± ± 1.5 ** 5.6 ± ± 0.8 ** K (kn.m ) 40.6 ± ± ± ± 7.4 * s ig n ificantly different from HT, p < 0.05 and * * significantly different from HT, p < 0.01 Table 2 Half squat (S) and bench press (BP) optimal force (F opt ), optimal velocity (V opt ), maximal power (P max ), and lower limb musculotendinous stiffness (K) for the whole group and each specialty (discus throwers, DT; hammer throwers, HT; and shotputters, SP). An interesting finding was the significant relationship between P max BP and SBP for the whole group ( Fig. 2b ). To the best of our knowledge, studies about upper limb muscle characteristics and performance in athletic throwing events are scarce. F opt BP was correlated with both body mass and SBP. In agreement with results of Terzis et al. [21], the present results demonstrated a significant influence of upper limb strength on SBP. Terzis et al. [21] also demonstrated that shotput performance was significantly correlated with elbow extensors maximal isokinetic torque, maximal bench press force (1 RM) and the area of type II myofibres. A recent study by Terzis et al. [22] confirmed the relationship between bench press 1 RM and shotput performance. The relationship between relative P max BP and SBP remained significant. In line with the significant correlation obtained between SBP and V opt BP, the present results indicate that upper limb velocity could influence SPB. This importance of upper limb velocity on variations in throwing performance is in agreement with the final acceleration of the implement by trunk and upper limb action. It has been demonstrated that movement velocity is related to the percentage of fast twitch fibres [10, 11, 20, 23, 24]. The significant relationship between type II triceps brachii fibre area and shotput performance obtained by Terzis et al. [21] underlines the importance of upper limb velocity characteristics in throwing performance. This analysis is in agreement with the fact that during the throw delivery phase, upper limb extension increases the implement velocity from 3 to 15 m.s for shotput throwing [13] and from 7 to 25 m.s for discus throwing [2]. The present results are also in agreement with the study of Marques et al. [14], the purpose of which was to explore the relationship between upper limb throwing velocity and powervelocity characteristics during bench press in elite handball players. The results demonstrate that upper limb throwing velocity is related to maximal dynamic strength, peak power and peak bar velocity. The three subgroups demonstrated similar power-velocity characteristics for lower limbs ( Table 2 ). This indicates that, despite technical differences between throwing subgroups, muscle function requirements were similar. The P max BP, VoptBP and F opt BP values were significantly lower for the HT subgroup. This result is consistent with the technique of hammer throwing in which the arms have to resist the centrifugal force generated by the implement. Interestingly, as shown in Fig. 3, K was correlated to SPB for each subgroup. The correlation between P max S and SBP was significant for the SP subgroup, demonstrated a trend for the HT subgroup and failed to be significant for the DT subgroup ( Fig. 2a ). This could mainly be attributed to the small size of the subgroups and / or SBP value homogeneity (the respective coefficients of variation for P max S and SBP were 14.2 % and 8.9 % for the DT subgroup vs % and 11.3 % for the SP subgroup and 20 % and 14.1 % for the HT subgroup). The correlations between P max BP and SBP were significant for each subgroup ( Fig. 2b ). This could be attributed to large variability in P max BP: 21.3 %, 31.5 % and 38.1 % for DT, SP and HT subgroups, respectively. The results for the subgroup are in line with those obtained for the whole group. However, analysis in subgroups underline the limits of statistical analysis and interpretation in small groups selected according to performance criteria. It makes it difficult to interpret the correlations for each subgroup. As an example, the benefit of upper limb velocity characteristic in hammer throw remains unclear to the authors. It can be concluded that upper and lower limb muscular characteristics were associated with throwing performance. The relationship between throwing performance and muscular characteristics differs when upper and lower limbs were considered. The main application of these findings could be to propose specific training for upper and lower limbs. Lastly, these results corroborate the relevance of squat and bench press exercises in determining the upper and lower limb muscular abilities in athletic throwing events. References 1 Bartlett RM. Principles of throwing. In: Zatsiorsky VM (ed.) Biomechanics in Sports: Performance Enhancement and Injury Prevention. Oxford: Blackwell Science Ltd ; 2000 ; Bartlett RM. The biomechanics of the discus throw: a review. J Sports Sci 1992 ; 10 : Bosco C, Belli A, Astrua M, Tihanyi J, Pozzo R, Kellis S, Tsarpela O, Foti C, Manno R, Tranquilli C. A dynamometer for evaluation of dynamic muscle work. Eur J Appl Physiol 1995 ; 70 : Bouhlel E, Chelly MS, Tabka Z, Shephard R. Relationships between maximal anaerobic power of the arms and legs and javelin performance. J Sports Med Phys Fitness 2007 ; 47 : Bret C, Rahmani A, Dufour A-B, Messonnier L, Lacour J-R. L eg st re ng th and stiffness as ability factors in 100 m sprint running. J Sports Med Phys Fitness 2002 ; 42 : Chelly SM, Denis C. Leg power and hopping stiffness: relationship with sprint running performance. Med Sci Sports Exerc 2001 ; 33 : Dalleau G, Belli A, Viale F, Lacour JR, Bourdin M. A simple method for field measurements of leg stiffness in hopping. Int J Sports Med 2004 ; 25 : Dorel S, Hautier CA, Rambaud O, Rouffet D, Van Praagh E, Lacour JR, Bourdin M. Torque and power-velocity relationships in cycling: relevance to track sprint performance in world-class cyclists. Int J Sports Med 2005 ; 26 : Harriss DJ, Atkinson G. International Journal of Sports Medicine Ethical Standards in Sport and Exercise Science Research. Int J Sports Med 2009 ; 30 :

6 510 Training & Testing 10 Hautier CA, Linossier M-T, Belli A, Lacour J-R, Arsac LM. Optimal velocity for maximal power production in non-isokinetic cycling is related to muscle fibre type composition. Eur J Appl Physiol 1996 ; 74 : Houston ME, Norman RW, Froese EA. Mechanical measures during maximal velocity knee extension exercise and their relation to fibre composition of the human vastus lateralis muscle. Eur J Appl Physiol 1988 ; 58 : Izquierdo M, Hakkinen K, Gonzalez-Badillo JJ, Ibanez J, Gorostiaga EM. E ffects of long-term training specificity on maximal strength and power of the upper and lower extremities in athletes from different sports. Eur J Appl Physiol 2002 ; 87 : Lanka J. Shot Putting. In: Zatsiorsky VM (ed.) Biomechanics in Sports: Performance Enhancement and Injury Prevention. Oxford: Blackwell Science Ltd ; 2000 ; Marques MC, van den Tilaar R, Vescovi JD, Gonzalez-Badillo JJ. Relationship between throwing velocity, muscle power, and bar velocity during bench press in elite handball players. Int J Sports Physiol Perform 2007 ; 2 : Murphy A, Watsford M, Coutts A, Pine M. Reliability of a test of musculotendinous stiffness for the triceps-surae. Phys Ther Sport 2003 ; 4 : Rahmani A, Dalleau G, Viale F, Hautier CA, Lacour J-R. Validity and reliability of a kinematic device for measuring the force developed during squatting. J Appl Biomech 2000 ; 16 : Rahmani A, Locatelli E, Lacour JR. Differences in morphology and force/ velocity relationship between Senegalese and Italian sprinters. Eur J Appl Physiol 2004 ; 91 : Rahmani A, Viale F, Dalleau G, Lacour J-R. Force/velocity and power/ velocity relationships in squat exercise. Eur J Appl Physiol 2001 ; 84 : Rambaud O, Rahmani A, Moyen B, Bourdin M. Importance of upperlimb inertia in calculating concentric bench press force. J Strength Cond Res 2008 ; 22 : Sargeant AJ. Human power output and muscle fatigue. Int J Sports Med 1994 ; 15 : Terzis G, Georgiadis G, Vassiliadou E, Manta P. Relationship between shot put performance and triceps brachii fiber type composition and power production. Eur J Appl Physiol 2003 ; 90 : Terzis G, Karampatsos G, Georgiadis G. Neuromuscular control and performance in shot-put athletes. J Sports Med Phys Fitness 2007 ; 47 : Thorstensson A, Grimby G, Karlsson J. Force-velocity relations and fiber composition in human knee extensor muscles. J Appl Physiol 1976 ; 40 : Tihanyi J, Apor P, Fekete G. Force-velocity-power characteristics and fiber composition in human knee extensor muscles. Eur J Appl Physiol 1982 ; 48 : Walshe AD, Wilson GJ, Murphy AJ. The validity and the reliability of a test of lower body musculotendinous stiffness. Eur J Appl Physiol 1996 ; 73 : Wilson GJ, Murphy AJ, Pryor JF. Musculotendinous stiffness: its relationship to eccentric, isometric, and concentric performance. J Appl Physiol 1994 ; 76 : Wilson GJ, Wood GA, Elliott BC. Optimal stiffness of series elastic component in a stretch-shorten cycle activity. J Appl Physiol 1991 ; 70 : Winter DA. Anthropometry Biomechanics of Human Movements. New York: John Wiley & Sons ; 1979 ; Young W, McLean B, Ardagna J. Relationship between strength qualities and sprinting performance. J Sports Med Phys Fitness 1995 ; 35 : 13 19