Soccer is a multifaceted team sport that requires well-developed speed and power to be played at an elite level (12,39), given that a number of laboratory and field tests have been proposed to assess explosive power of selected population of soccer players (38). Recently, vertical jump height was shown to be significantly related to short sprint performance (10-30 meters) in well-trained elite soccer players (39). Furthermore, Arnason et al. (1) showed that vertical jump performance was related to team success in semiprofessional soccer players.
Despite its wide use in soccer (38), vertical jump (height jumped) testing requires specific testing setup and devices (i.e., force platform and switch mats) that may limit its use in field conditions. Additionally, Rampinini et al. (29) showed that vertical jump performance was not related to actual match activities in elite-level professional soccer players.
Recent studies have proposed the 5-jump test (5JT) for distance as a practical alternative to estimate lower limb explosive power of selected population of athletes (5,9,28,34,35,37) including soccer players (31,36).
The 5JT consists of 5 consecutive strides with joined feet position at the start and end of the jumps. With respect to other tests, the 5JT is very easy to perform and does not require any sophisticated equipment. 5JT performance is usually expressed in absolute terms as the overall distance covered (i.e., in meters) and is then very easy to perform. Nevertheless, the height of the subject can play a significant role in the performance since, with equivalent slit, the strides are proportional to the length of the lower limbs, favoring tall athletes. Furthermore, because 5JT involves a body mass displacement within a limited lapse of time, similar absolute distance achievements may require important differences in force/power expression in subjects with different body masses (7). Thus, strategies to account for difference in body size when evaluating athletes' 5JT performance (i.e., relative and absolute performances) might be of great interest for those involved with field testing.
Despite its proposed practicability and utilization (9,28,31,34-37), no study has been carried out in order to specifically investigate the nature of the 5JT and how to express the results of the test in soccer players. Therefore, the aims of the present study were to test the external validity of the 5JT and to improve the diagnostic value of the 5JT in soccer players.
Experimental Approach to the Problem
The 5JT is currently used in field conditions with the aim to estimate athletes' lower limb explosive power (9,28,31,34-37) and to measure horizontal stretch-shortening cycle capabilities in the distance traveled using lower limb actions similar to those of the sprint stride usually performed by soccer players (36). Moreover, the 5JT has been recently proposed as test to successfully assess the insurgence of training adaptations in endurance athletes (34,35,37). 5JT performance is usually reported as the total distance covered (in meters); however, this notation may mask differences in body size and thus giving misleading results.
In fact, tall athletes may perform better than shorter ones because of their greater lower limb length. Additionally, heavier subjects may have their 5JT performance underestimated in terms of power expressed (7). In order to improve the diagnostic strength of the 5JT, we proposed relative and body mass-dependent notations that may account for the limitation involved with the absolute expression of results.
As athletic squads are usually composed of subjects differing in body height (38), we proposed a relative expression of 5JT performance (5JT-relative) taking into account the subjects' lower limb length. In order to achieve this, 5JT performance was divided by 5 to obtain an average tread value (1Tread). 1Tread was then divided by the length of the lower limbs (5JT-relative = 1Tread/LgLowLimbs). With the aim of accounting for the difference in body mass between athletes, the absolute 5JT performance was multiplied by the individual body mass (5JT-body mass = 5JT × body mass). This notation was used because it could be considered a rough measure of work performed over the distance jumped by the subject (work = distance × force).
Dimensional scaling should be considered when evaluating strength measures (6,7,17,21,40). In two geometrically similar and quantitatively identical individuals, one may expect all linear dimensions (L) to be proportional. The length of the arms, legs, and individual muscles will have a ratio of L:1, the cross-section area L2:1, and the volume ratio L3:1. Since muscular strength is directly proportional to the muscle cross-sectional area and body mass (mb) varies directly with body volume, whole-body muscular strength measures will vary in proportion to mb0.67. Given that, in the present study, peaks of force, torque, and power variables were therefore expressed in N·kg−0.67, N·m·kg−0.67, and W·kg−0.67, respectively. Dimensional scaling should ideally be based on fat-free mass because fat has very low metabolic activity (2). We chose to use dimensional scaling based on body mass to allow the possibility of direct comparison of our results to other studies (8,16,40).
The work hypothesis was that these new notations could further improve the diagnostic power of the 5JT.
Despite the popularity of the 5JT (9,28,31,34-37), to our knowledge, no studies are currently available investigating the performance components of this field test. Thus, in the present study, 5JT performance expressed either in absolute, relative, or mass-dependent terms was compared with laboratory tests of vertical jump performance (4,14) and isokinetic leg-extension strength testing (32) for external validity and to examine in detail the determining variables of 5JT performance. Information in this context may be of great help to coaches and fitness trainers for training monitoring and prescription.
Fifteen elite-level male soccer players, all members of the Under-23 Tunisian National Olympic team, volunteered to participate in the study. Players' physical characteristics are presented in Table 1. Subjects' body fat percentage was calculated according to the formula of Siri (33) based on four skinfold measurements (biceps, triceps, subscapularis, and suprailiac)(13).
Before the start of this study, the subjects were informed about the test protocols, but blinded about the aims of the investigation. In order to be included in the investigation, each subject provided written informed consent in accordance with the Declaration of Helsinki. Participants were aware that they could withdraw from the study at any time.
All players were starters in their senior teams participating in the Tunisian national soccer championship. At the time of the experiment, their weekly training schedule included 6-9 training sessions per week (approximately 90 minutes per training session). A training session consisted mainly in soccer training and very rarely in track running or muscular strengthening. Official games took place once weekly, usually on weekends. The investigation was carried out at mid-season while the national team was engaged in the qualifications for the Olympic Games (Athens 2004) and was leading the continental group. The studied cohort was composed of 2 goal keepers, 4 defenders, 6 mid-field players, and 3 forwards. The research design gained clearance from the University of Tunis Ethical Committee before the start of the testing sessions and subject recruitment.
The participants came to the laboratory for a physical examination and anthropometric measurements. Lower limb length was measured by subtracting their seated height from their body height. The players then performed the 2 laboratory tests, and 1 week later performed the field 5JT. Both testing sessions were performed on Wednesday (i.e., away from Sunday official games). Each player was instructed and verbally encouraged to give their maximal effort during all tests. The subjects were familiar with the testing procedures undertaken as they routinely performed these tests as a part of their scientific follow-up. Laboratory testing was scheduled between 9:00 and 11:00 am (19°C) and was performed by the subjects wearing shorts and T-shirts. The 5JT was performed from 10:00 to 11:00 am (18°C) with subjects wearing soccer sportswear. Testing on both days was performed after a standardized caffeine-free breakfast for each player.
A standardized warm-up consisting of 10 minutes of jogging and 5 minutes of coordination movements was performed before the lab and field tests. Thereafter, a 5-minute specific warm-up was performed using exercises mimicking and priming test movements. No static passive stretching was allowed during warm-up (10,22,23,27), and 3 minutes of recovery separated the warm-up from the tests.
Force Plate Vertical Jumping
The subjects performed 2 jumping protocols on a force platform (Kistler 9281 C; Kistler, Winterthur, Switzerland). The first protocol consisted of jumping from a fixed semisquat position with the hands held at the hips [squat jump (SJ)]. The second vertical jump test was a free counter movement jump during which the players freely used their hands while jumping [arm-aided countermovement jump (arm-CMJ)]. Each player performed 3 SJs and 3 arm-CMJs with 2 minutes of rest in between. The best jump of each jumping protocol was selected for analysis. Peak jumping force (Fpeak), peak jumping velocity [peak jumping power (Wpeak), and the peak height of the jumps (Hpeak)] were recorded (8).
Vertical jump performance was used as paradigm for explosive strength and lower limb abilities as recent studies showed that maximal power development is not significantly different between vertical and horizontal jumps (30).
Each player was placed in an upright seated position and secured to both the dynamometer (Cybex NORM; Henley Healthcare, Cybex International, Inc., Medway, MA) and the corresponding chair according to manufacturer specifications in order to eliminate extraneous movements and to maintain a constant hip joint angle (90°). Two maximal voluntary measurements were made at 90°·s−1 (1·57 rad·s−1) and 240°·s−1 (4.19 rad·s−1) angular velocities. At each velocity, 3 extension/flexion movements of the leg were allowed as a habituation movement, followed by 1 minute of rest. Thereafter, 5 and 20 maximal extension/flexions were performed at 90°·s−1 and 240°·s−1, respectively, with 2 minutes of recovery between series. Each knee extension/flexion was performed from an initial knee angle of approximately 110° and went through a full range of motion to a final knee angle of 0°. The NORM system sensitivity was set at 5 for both measurements according to the manufacturer's recommendations, and peak torque was calculated and adjusted for the effects of gravity by the NORM system software (27). The right leg was tested first, then after having measured the left leg gravity, the left leg evaluation began. For each angular velocity, the best extension/flexion repetition was kept for analysis of peak torque and mean power. The recorded isokinetic variables were as follows: peak torque (N·m, and N·m·kg−0.67), Mean Power (W and W·kg−0.67), and time to reach the imposed angular velocity [acceleration time (AT) in seconds]. Calculations were performed, averaging the left and right leg values of knee flexor and extensor scores.
This test was performed on the grass with the players equipped with appropriate soccer boots. The 5JT consists of 5 consecutive strides with joined feet position at the start and end of the jumps. From the starting joined feet position, the participant was not allowed to perform any back step with any foot; rather, he had to directly jump to the front with a leg of his choice. After the first 4 strides, i.e., alternating left and right feet for 2 times each, he had to perform the last stride and end the test again with joined feet. If the player fell back on completion of the last stride, the test was performed again (only 2 cases of this happening in the present study). 5JT performance was measured with a tape measure from the front edge of the player's feet at the starting position to the rear edge of the feet at the final position. The person assessing the landing had to focus on the last stride of the player in order to exactly determine the last foot print on the grass, as the players could not always stay on their feet on landing. The starting position was set on a fixed point.
Reliability of 5JT performance was assessed before the start of this study, making elite soccer players (n = 67) repeat the test 1 week apart. Results showed an intraclass correlation (ICC) of 0.91 for 5JT performance. The resulting typical error of measure as a coefficient of variation (TEM) was 2.2% (3,18,20). These findings are similar to those previously reported by Slattery et al. (35) for experienced triathletes (TEM = 2.3%, ICC = 0.94).
Values are expressed as mean ± SD A Pearson correlation matrix was performed among the variables of the vertical jump (Hpeak, Wpeak, Wpeak·kg−0.67, Fpeak) and isokinetic tests (peak torque and AT) and 5JT notations considered as independent variables. Statistical significance was fixed at p ≤ 0.05.
Results from the different tests are summarized in Table 2. Table 3 shows the main results of the correlation matrix between 5JT performance and vertical jump data. There were significant correlations of both absolute and scaled (kg−0.67) expressions of 5JT performance with all SJ variables except the Fpeak variable. Arm-CMJ variables showed a significant correlation with 5JT-relative and 5JT-body mass performances. 5JT-relative and 5JT-body mass correlated significantly with knee extensors 240°·s−1 (r = 0.60, p < 0.05) and knee flexors 90°·s−1 (r = 0.67, p = 0.006) AT performance, respectively.
The present study showed that 5JT performance was significantly correlated with vertical jump height and power variables and 1 explosiveness variable measured during isokinetic testing. Specifically, 5JT-relative was significantly correlated with laboratory tests in more cases than the absolute form (Table 3).
In order to take into account differences in body weight, we estimated the amount of work performed during the 5JT. Results showed that 5JT-body mass was strongly correlated with SJ peak power and to a lesser extent with SJ peak force (r = 0.82, p < 0.0001 and r = 0.67, p = 0.006, respectively). Similarly, arm-CMJ peak power and force were revealed to be significantly related to 5JT-body mass (r = 0.54, p = 0.04 and r = 0.65, p = 0.009, respectively). These findings demonstrate that by simply multiplying 5JT performance by body mass, we can obtain a measure that is significantly related to explosive strength (4).
5JT performance was significantly related to SJ scaled (kg−0.67) power output (r = 0.77, p = 0.001) and to a lesser extent (r = 0.58, p = 0.024) to absolute SJ power output. This means that 5JT performance depends mostly on the explosive strength ability of subjects and that body weight may be regarded as a 5JT performance-limiting factor (7). Peak explosive strength was related to 5JT performance only when expressed with body mass-dependent notation (r = 0.67, p = 0.006 and r = 0.65, p = 0.009 for SJ and arm-CMJ, respectively). These findings were expected as we thought that 5JT-body mass performance could be regarded as a reflection of work exerted during 5JT (work = distance × force). However, because 5JT-body mass was strongly related to SJ power output (r = 0.82, p = 0.000), contraction speed may have influenced performance (power = force × speed). As a result, the 5JT may be regarded as a very useful and simple testing tool that provides information about athletes' stride power, which is considered a crucial variable in many sport activities, such as team sports (26).
Nevertheless, 5JT performance, differently from vertical jump and isokinetic tests, measures horizontal stretch-shortening cycle capabilities in distance (36). Consequently, this may explain why the shared common variance (r2) between 5JT performance and vertical jump and isokinetic peak variables was higher than 50% in only few cases (11). However, although the differences in exercise mode are evident between 5JT and lab tests (i.e., vertical jump and isokinetic extension), the muscular groups recruited are mainly the same. This possibly explains the positive correlations observed in the present study.
The results of the present study show that absolute and body mass-dependent expressions of 5JT performance may be regarded as a valid estimate of explosive power (11) such as that developed during the SJ. Nevertheless, as seen in Table 2, arm-CMJ power and force correlated significantly only with the 5JT-relative and 5JT-body mass, respectively. These findings suggest that the ability to develop high power force peaks during stretch-shortening cycle actions may positively affect 5JT performance when considered in relative or body mass-dependent terms. However, coordination factors may also have had some influence on the relationship between SJ and arm-CMJ with 5JT performance. In fact, studies that addressed the performance difference between arm-CMJ and the SJ showed that muscle coordination may play an important role. This is probably due to coordination factors representing the main difference between the arm-CMJ and the SJ (15,24,25).
Thus, we emphasize the importance of the relative expression of the 5JT, i.e., 5JT-relative, which was found to be correlated with both vertical jump performances (arm-CMJ and SJ) and acceleration time of knee extensors in isokinetic testing.
As it is very easy to perform, sensitive to training effects (28,34), and valid with respect to anaerobic tests, we strongly recommend the use of the 5JT in order to assess soccer players' stride power. Indeed, soccer performance depends not only on endurance and repeated sprint ability, but also on the players' power for a number of actions during the game, even if it is well-known that soccer players are far from being the most powerful athletes (38). In heterogeneous groups of players with respect to body height and mass, the relative expression and the body mass-dependent notation of 5JT performance should be used for comparison purposes (7).
The results of this study indicate that the 5JT may be an appropriate field test for measuring stride power in soccer players. The use of the 5JT as measure of lower limb explosive power is even more attractive because of the limited facilities needed compared to vertical jumping or for reliable short-distance sprinting. As a result, it could be suggested that coaches who do not have direct access to laboratory equipment can use the 5JT to test lower limb horizontal explosive power, a performance variable that is very close to running movement (i.e., logical validity) and other training methods for the development of explosiveness in soccer players (26,36). In addition, 2 simple anthropometric measures (body mass and seated heights) allow the calculation of 5JT performance notations, which are very practical when comparing athletes differing in body size.
The study results are similar to those recently reported by Bouhlel et al. (5) for children (age, 12 ± 0.4 years). In that study, a significant relationship was reported between 5JT performance (distance) and CMJ height (r = 0.63, p < 0.01) and relative power (W·kg−1, r = 0.74, p < 0.001). This supports the validity of the 5JT in evaluating lower limb explosiveness.
With respect to 5JT performance, Paavolainen et al. (28) reported values increasing from 12.47 to 13.04 meters in the experimental training group that concomitantly increased its endurance performance. Assuming a body height-to-LgLowLimbs ratio similar to that observed in the present study, the calculated 5JT-relative values of Paavolainen et al. (28) are around 2.94 and 2.92 for the experimental and control groups, respectively. This is very close to the 2.91 mean value found in the present study. This is an average value with respect to stride power. Indeed, the maximal single player values observed are >3.00, (i.e., 3.13) for the present study and 3.22 for a senior player (personal data). Values >3.2 could be interpreted as reflecting good muscular power and values <2.8 as weak values.
Recent studies have shown that the 5JT is a valid test to assess training adaptation in a selected population of athletes (9,28,31,34-37). In this regard, training improvement in 5JT performance should be >2.2% in order to be considered meaningful (18-20) in well-trained soccer players.
The authors thank the coaches Khemaïes Laabidi and Boubaker Hannachi as well as the National Technical Director of the Tunisian Soccer Federation: Belhassen Malouche, and the CNMSS physiotherapists Amel Hammouda and Néjib Tekaïa for their technical support. This study was financially supported by the Ministère de la Recherche Scientifique et du développement des compétences, Tunisia. The authors have no conflicts of interest that are directly relevant to the content of this review.
1. Arnason, A, Sigurdsson, SB, Gudmundsson, A, Holme, I, Engebretsen, L, and Bahr, R. Physical fitness, injuries, and team performance in soccer
. Med Sci Sports Exerc
36: 278-285, 2004.
2. Åstrand, PO and Rodahl, K. Textbook of Work Physiology-Physiological Bases of Exercise
(3rd ed.) New York: McGraw-Hill; 1986.
3. Batterham, AM and Hopkins, WG. Making meaningful inferences about magnitudes. Int J Sports Physiol Perform
1: 18-25, 2006.
4. Bosco, C, Luhtanen, P, and Komi, PV. A simple method for measurement of mechanical power in jumping. Eur J Appl Physiol
50: 273-282, 1983.
5. Bouhlel, E, Bouhlel, H, Chelly, MS, and Tabka, Z. Relationship between maximal anaerobic power measured by force-velocity test and performance in the counter movement jump and in the 5-jump test in moderately trained boys. Sci Sports
21: 1-7, 2006.
6. Challis, JH. Methodological report: the appropriate scaling of weightlifting performance. J Strength Cond Res
13: 367-371, 1999.
7. Challis, JH. Examination of the scaling of human jumping. J Strength Cond Res
18: 803-809, 2004.
8. Chamari, K, Hachana, Y, Ahmed, YB, Galy, O, Sghaier, F, Chatard, JC, Hue, O, and Wisløff, U. Field and laboratory testing in young elite soccer
players. Br J Sports Med
38: 191-196, 2004.
9. Chtara, M, Chamari, K, Chaouachi, M, Chaouachi, A, Koubaa, D, Feki, Y, Millet, GP, and Amri, M. Effects of intra-session concurrent endurance and strength training sequence on aerobic performance and capacity. Br J Sports Med
39: 555-560, 2005.
10. Church, JB, Wiggins, MS, Moode, FM, and Crist, R. Effect of warm-up and flexibility treatments on vertical jump
performance. J Strength Cond Res
15: 332-336, 2001.
11. Clarke, D and Clarke, H. Research Processes in Physical Education, Recreation and Health
Englewood Cliff, NJ: Prentice-Hall; 1970.
12. Cometti, G, Maffiuletti, NA, Pousson, M, Chatard, JC, and Maffulli, N. Isokinetic
strength and anaerobic power of elite, subelite and amateur French soccer
players. Int J Sports Med
22: 45-51, 2001.
13. Cosgrove, MJ, Wilson, J, Watt, D, and Grant, SF. The relationship between selected physiological variables of rowers and rowing performance as determined by a 2000 m ergometer test. J Sports Sci
17: 845-852, 1999.
14. Davies, CTM and Rennie, R. Human power output. Nature
217: 770-771, 1968.
15. Harman, EA, Rosenstein, MT, Frykman, PN, and Rosenstein, RM. The effects of arms and countermovement on vertical jumping. Med Sci Sports Exerc
6: 825-833, 1990.
16. Helgerud, J, Engen, LC, Wisløff, U, and Hoff, J. Aerobic endurance training improves soccer
performance. Med Sci Sports Exerc
33: 1925-1931, 2001.
17. Hoff, J, Kemi, OJ, and Helgerud, J. Strength and endurance differences between elite and junior elite ice hockey players. The importance of allometric scaling
. Int J Sports Med
26: 537-541, 2005.
18. Hopkins, WG. Measures of reliability in sports medicine and science. Sports Med
30: 1-15, 2000.
19. Hopkins, WG and Hewson, DJ. Variability of competitive performance of distance runners. Med Sci Sports Exerc
33: 1588-1592, 2001.
20. Hopkins, WG, Schabort, EJ, and Hawley, JA. Reliability of power in physical performance tests. Sports Med
31: 211-234, 2001.
21. Jaric, S, Radosavljevic-Jaric, S, and Johansson, H. Muscle force and muscle torque in humans require different methods when adjusting for differences in body size. Eur J Appl Physiol
87: 304-307, 2002.
22. Knudson, D, Bennett, K, Corn, R, Leick, D, and Smith, C. Acute effects of stretching are not evident in the kinematics of the vertical jump
. J Strength Cond Res
15: 98-101, 2001.
23. Kokkonen, J, Nelson, AG, and Cornwell, A. Acute muscle stretching inhibits maximal strength performances. Res Q Exerc Sport
69: 411-415, 1998.
24. Lees, A, Vanrenterghem, J, and De Clercq, D. Understanding how an arm swing enhances performance in the vertical jump
. J Biomech
37: 1929-1940, 2004.
25. Lees, A, Vanrenterghem, J, and De Clercq, D. The energetics and benefit of an arm swing in submaximal and maximal vertical jump
performance. J Sports Sci
24: 51-57, 2006.
26. Murphy, AJ, Lockie, RG, and Coutts, AJ. Kinematic determinants of early acceleration in field sport athletes. J Sports Sci Med
2: 144-150, 2003.
27. Nelson, AG, Guillory, IK, Cornwell, A, and Kokkonen, J. Inhibition of maximal voluntary isokinetic
torque production following stretching is velocity-specific. J Strength Cond Res
15: 241-246, 2001.
28. Paavolainen, L, Häkkinen, K, Hämäläinen, I, Nummela, A, and Rusko, H. Explosive-strength training improves 5-km running time by improving running economy and muscle power. J Appl Physiol
86: 1527-1533, 1999.
29. Rampinini, E, Bishop, D, Marcora, SM, Ferrari Bravo, D, Sassi, R, and Impellizzeri, FM. Validity of simple field tests as indicators of match-related physical performance in top-level professional soccer
players. Int J Sports Med
28: 228-235, 2007.
30. Ridderikhoff, A, Batelaan, JH, and Bobbert, MF. Jumping for distance: control of the external force in squat jumps. Med Sci Sports Exerc
31: 1196-1204, 1999.
31. Rohr, G. Elaboration de batteries de tests d'évaluation spécifique du jeune fooballeur. Bordeaux, France: Université de II; 1992.
32. Sale, DG. Testing strength and power. In: Physiological Testing of the High-Performance Athlete
MacDougall, JD, Wenger, HA, and Green, HJ, eds. Human Champaign, Ill: Kinetics Books; 1991. pp. 21-106.
33. Siri, WE. Body composition from fluid spaces and density: analysis of methods, In: Techniques for Measuring Body Composition
J. Brozek and A. Henschel, eds. Washington, DC: National Research Council, 1961. pp. 223-244.
34. Slattery, KM. Practical Tests for Monitoring Fatigue and Recovery in Triathletes. School of Leisure, Sport and Tourism. Sydney, Australia: University of Technology; 2004.
35. Slattery, KM, Wallace, LK, Murphy, AJ, and Coutts, AJ. Physiological determinants of three-kilometer running performance in experienced triathletes. J Strength Cond Res
20: 47-52, 2006.
36. Spinks, CD, Murphy, AJ, Spinks, WL, and Lockie, RG. The effects of resisted sprint training on acceleration performance and kinematics in soccer
, rugby union, and Australian football
players. J Strength Cond Res
21: 77-85, 2007.
37. Spurrs, RW, Murphy, AJ, and Watsford, ML. The effect of plyometric training on distance running performance. Eur J Appl Physiol
89: 1-7, 2003.
38. Stølen, T, Chamari, K, Castagna, C, and Wisløff, U. Physiology of soccer
: an update. Sports Med
35: 501-536, 2005.
39. Wisløff, U, Castagna, C, Helgerud, J, Jones, R, and Hoff, J. Maximal squat strength is strongly correlated to sprint-performance and vertical jump
height in elite soccer
players. Br J Sports Med
38: 285-288, 2004.
40. Wisløff, U, Helgerud, J, and Hoff, J. Strength and endurance of elite soccer
players. Med Sci Sports Exerc
30: 462-467, 1998.
Keywords:© 2008 National Strength and Conditioning Association
soccer; vertical jump; isokinetic; allometric scaling; explosive strength; football