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1 Variability of plyometric and ballistic exercise technique maintains jump performance
2 ABSTRACT
4 The aim of this study was to investigate changes in vertical jump technique over the course of a training session.
5 Twelve plyometric and ballistic exercise trained male athletes (age = 23.4 ± 4.6 years, body mass = 78.7 ± 18.
6 kg, height = 177.1 ± 9.0 cm) performed three sets of 10 repetitions of drop (DJ), rebound (RJ) and squat jumps
7 (SJ). Each exercise was analysed from touch down to peak joint flexion and peak joint flexion to take-off. SJ
8 where analysed from peak joint flexion to take-off only. Jump height, flexion and extension time and range of
9 motion, and instantaneous angles of the ankle, knee and hip joints were measured. Separate one-way repeated
10 ANOVAs compared vertical jump technique across exercise sets and repetitions. Exercise set analysis found SJ
11 had lower results than DJ and RJ for the angle at peak joint flexion for the hip, knee and ankle joints and take-off
12 angle of the hip joint. Exercise repetition analysis found the ankle joint had variable differences for the angle at
13 take-off, flexion and extension time for RJ. The knee joint had variable differences for flexion time for DJ and
14 angle at take-off and touch down for RJ. There was no difference in jump height. Variation in measured
15 parameters across repetitions highlights variable technique across plyometric and ballistic exercises. This did not
16 affect jump performance, but likely maintained jump performance by overcoming constrains (e.g. level of rate
17 coding).
19 INTRODUCTION
21 Plyometric and ballistic exercises are common place in athletic training for many sports to improve vertical jump
22 performance. Plyometric exercise refers to the use of the stretch-shortening cycle, where a high-intensity eccentric
23 contraction occurs immediately before a rapid concentric contraction (18). Plyometric exercises usually involve
24 various types of body weight jumping, such as drop jumps (DJ) and countermovement jumps (CMJ). Ballistic 25 exercise is defined by the explosive release of the body in to the air, but the overall duration of the exercise is 26 longer mainly due to an extended ground contact time, such as a squat jump (SJ).
28 Numerous studies have found improvement in vertical jump performance after a period of vertical jump training 29 incorporating both ballistic and plyometric exercises. A meaningful improvement of 4.8 cm have been found in 30 CMJ height after six weeks of vertical jump training in basketball athletes (19). Further significant improvements 31 of 13.2% have been found in CMJ height after six weeks of additional vertical jump exercise in athletic training 32 (24). Periods of plyometric training have also been found to increase vertical jump height in both male (7) and 33 female athletes (22), thus justifying its inclusion in athletic training to improve jump performance in all athletic 34 populations.
36 Plyometric and ballistic exercise technique has been extensively researched to find methods of improving jump 37 performance (8, 20, 25, 26). Jump height is considered the main performance output of a ballistic and plyometric 38 exercise, therefore is extensively measured my strength and conditioning coaches to identify the best jump 39 technique. A Greater squat depth is argued to produce a greater jump height in a SJ (8, 20). A greater net impulse 40 was found with greater squat depth (8), due to greater amount of time taken to execute the jump, which may cause 41 the greater jump height. Although, a CMJ has found to have a greater jumper height than a SJ, and further had a 42 greater impulse during smaller squat depths (20). Thus, opposite of SJ, a greater force is produced relative to time 43 in a CMJ with less of a squat depth creating a greater jump height.
45 The literature suggests several methods for increases in jump height caused by better jump technique, therefore 46 jump height alone does not identify how said jump is achieved. Measurement of kinetic parameters, such as peak 47 ground reaction force or impulse, would better identify vertical jump intensity, but would be influenced by range 48 of motion and jump timings during different phases (i.e. touchdown, peak joint flexion and take-off) of a ballistic
71 Data for this study was collected from 12 athletes, experienced in plyometric and ballistic exercise training. Prior 72 to completing the study, all participants passed the NSCA recommendations for prerequisites of completing 73 plyometric exercise (2). This study was a cross sectional study design.
75 Subjects 76 Twelve male athletes (age = 23.4 ± 4.6, body mass = 78.7 ± 18.8 kg, height = 177.1 ± 9.0 cm), experienced in 77 plyometric and ballistic exercise training and participated in lower body power sports (e.g. Judo, Javelin, 78 Sprinting), volunteered to participate in the study. All participants competed at club level, and testing was 79 complete in the off-season of each sport.
81 The study was approved by a University ethics board prior to starting. All participants received a clear explanation 82 of the study including the benefits and risks of the investigation prior to signing an institutionally approved 83 informed consent document to participate in the study. No funding or endorsements were used in this study
85 Procedures 86 All participants completed a familiarisation and a testing session separated by 72 hours. All sessions were 87 complete at the same time of day to allow for variations in strength gains due to training at different times of the 88 day (23). Participants were asked to refrain from any form of exercise 72 hours before testing. Participants were 89 further asked to maintain the same level of hydration and continue a regular eating pattern prior to each laboratory 90 visit.
92 Familiarisation and testing sessions were identical except no measurements were taken during the familiarisation 93 session. All sessions involved the same plyometric exercises; DJ, rebound jump (RJ) and SJ. The DJ involved 94 participants dropping off a 40 cm high box leading with their dominant leg. Dominant leg was determined by 95 asking the participant. The 40 cm drop height was selected as it is reportedly in the range of optimal dropping
96 height (40-60 cm), measured in 19 young participants (1). The RJ involved repetitive CMJ to a self-selected depth, 97 initiated by a CMJ. The first jump was not analysed due to it not been a true rebound jump, as a jump did not 98 precede it. The SJ involved a countermovement to a self-selected depth to initiate the beginning of the jump, but 99 participants were instructed to hold for three seconds at the bottom of the countermovement before completing a 100 maximal jump. If the position was not held at the bottom of the countermovement for three seconds, the jump 101 was discounted and completed again.
103 During the DJ and RJ all participants were instructed to jump as high and as fast as possible with minimum ground 104 contact, whereas for the SJ participants were instructed to jump as high as possible. All jumps were completed 105 with arm swing to reflect a true training session and achieve maximal height.
107 All sessions started with a warm up, consisting of 10 minutes cycling at 100 W, followed by 10 minutes of 108 dynamic stretches. The participants then completed three submaximal repetitions of each plyometric and ballistic 109 exercise with two minutes rest in between. This allowed for the experimenter, an accredited strength and 110 conditioning coach, to assess appropriate technique. Appropriate technique for all exercises included bilateral 111 landing, with stable ankle, knee and hip joints, with no forward trunk lean.
113 The familiarisation and testing session consisted of three sets of 10 repetitions of DJ, RJ and SJ, completed in that 114 order to represent a typical training session. Three minutes of rest between sets was allowed to meet 115 recommendations of an optimal work to rest ratio of 1:5 to 1:10 (2). The number of foot contacts, 120, matched 116 recommendations for intermediate athletes as all athletes had experience of plyometric and ballistic exercises in 117 their own training and sport (2).
119 All exercises were completed on a force plate (Bertec, Columbus, U.S.A). The force plate was used to determine 120 parameters mentioned later in this methodology. 10 mm spherical markers were attached to the fifth metatarsal,
145 Statistical analysis was completed on sets of plyometric and ballistic exercises (exercise sets) and repetitions of 146 plyometric and ballistic exercises (exercise repetitions) to determine differences between vertical jump exercise 147 sets and repetitions. Exercise sets were calculated by the mean scores for each vertical jump exercise set. Exercise 148 repetitions were calculated by the mean of each repetition of vertical jump exercise.
150 Initial testing of normality and homogeneity of variance of data was completed to determine the use of a 151 parametric or none parametric tests. For data that passed these tests, separate one-way repeated ANOVA tests 152 were complete to determine differences between vertical jump exercise sets and exercise repetitions. Where 153 significant differences were detected a paired samples t-test was used to determine the differences.
155 If the test of normality or homogeneity of variance was not met, a non-parametric equivalent test was complete. 156 In this case, the Freidman’s test determined any differences between vertical jump exercise sets and exercise 157 repetitions. Where significance was found, a Wilcoxon’s signed rank test was completed with manual Bonferroni 158 adjustments to determine the differences. Significance for all tests was set at p < .05.
160 Cohen’s d effect size (ES) was used to calculate practically meaningful differences among all measured 161 parameters. ESs of <0.2, 0.2-0.6, 0.61-1.2 and >1.2 were considered trivial, small, moderate and large, 162 respectively (3). Infraclass correlations coefficients (ICC) were calculated of each exercise for each kinematic 163 parameter to determine reliability of each kinematic measurement. The ICC classifications of Fleiss (less than 164 0.4 was poor, between 0.4 and 0.75 was fair to good, and greater than 0.75 is excellent) were used to describe the 165 range of ICC values (10). All statistical analyses were performed in SPSS (version 22.0, SPSS Science Inc, 166 Chicago, IL, USA).
168 RESULTS
170 ICC results show kinematic measures of plyometric and ballistics exercises to be reliable (Table 1). Results of 171 exercise sets analysis showed significant differences between all kinematic parameters. Post hoc analysis of 172 exercise set results are shown in Tables 2, 3 and 4. 173 Insert table 1 about here 174 Insert table 2 about here 175 Insert table 3 about here 176 Insert table 4 about here 177 Results of the analysis of exercise repetitions for the knee joint showed significant differences between repetitions 178 for DJ flexion time (P = 0.01, ES = 0.84 – 0.58). The repetition significant difference for DJ knee flexion time is 179 shown in Figure 1. RJ knee joint angle at touch down (P = 0.03, ES = 1.10 - 0.66), angle at take-off (P = 0.03, ES 180 = 0.78 – 0.58) and flexion time (P = 0.04, ES = 0.72 – 0.84) found significant difference between repetitions. The 181 repetition significant differences for the knee joint of the RJ are shown in Figure 2. SJ angle at touch down (P = 182 0.01, ES = 0.78 – 0.55) and extension range (P = 0.01, ES = 0.84 – 0.55) found significant differences between 183 repetitions for the knee. The significant repetition differences of the knee joint for the SJ are shown in Figure 3. 184 Significant differences of the ankle joint between repetitions were found for DJ angle at touch down (P = 0.03, 185 ES = 0.89 – 0.72), with significant differences shown in Figure 4. RJ ankle angle at take-off (P = 0.03, ES = 0. 186 – 0.66), flexion time (P = 0.01, ES = 0.81 – 0.58) and extension time (P = 0.05, ES = 0.81 – 0.58) found significant 187 difference between repetitions. The significant differences between repetitions are shown in Figure 5. Significant 188 differences of the hip joint between repetitions were only found for SJ angle at touch down (P = 0.01, ES = 0. 189 – 0.58). The significant difference between repetitions are shown in Figure 6. 190 Insert figure 1 about here 191 Insert figure 2 about here 192 Insert figure 3 about here
217 The present study found DJ jump height to be lower than RJ and SJ. This is not consistent with previous literature 218 with numerous studies finding DJ and RJ to have a greater jump height than SJ. Previous research found a 23 cm 219 difference between DJ and SJ (12), and an average of 2.4 cm difference between CMJ and SJ (4). This was 220 attributed to agonist muscles having greater time to develop more cross-bridge attachments during muscle 221 contraction. This led to greater moments at the hip, knee and plantarflexion leading to greater force production 222 (4). Greater electromyography activity in active muscles during a CMJ has been found, which was attributed to 223 greater muscle activation and elastic recoil (9). Further suggested mechanisms involve a pre-stretch created by 224 the countermovement in DJ and RJ led to storage of energy in the serial elastic elements, which was later utilized 225 when muscles act concentrically to increase jump height (13). The literature suggests numerous reasons for the 226 greater jump height in DJ and RJ. It would be reasonable to suggest that not one mechanism is the cause of the 227 greater jump height, but a combination of all mechanisms.
229 Although, Kotzamanidis et al. (2005) is in agreement with the present study finding DJ to have the lowest jump 230 height of 20.07 cm, compared to SJ and RJ with jump heights of 25.51 cm and 27.83 cm, respectively (14). This 231 may be due to a longer pre-stretch time leading to less energy transferred to the series elastic element, causing a 232 lower net impulse, for further utilization. Participants not been able to attenuate the large impact forces on initial 233 landing may cause the longer pre-stretch time where less force is transferred to the propulsive phase of the jump. 234 Therefore, use of a lower drop height for DJ may benefit some athletes that cannot attenuate impact forces from 235 larger drop heights. Ground reaction forces can be used to monitor attenuation of impact forces to help the strength 236 and conditioning coach progress drop heights for DJ exercises.
238 Results of exercise repetition analysis show variability between kinematic parameters. For example, during the 239 RJ exercise, the knee angle at touch down for repetition 10 of set 1 is significantly different to repetition 4, 7 and
240 9 of the same set, but repetition 10 of set two has no significant difference to any other repetitions. This highlights 241 variation in vertical jump technique throughout the course of the training session. Similar variability was found 242 when investigating basketball free throw technique (5). The authors found variability in wrist and elbow angle to 243 adapt to constraints in release parameters of the ball (5). The variability of technique were made to maintain 244 shooting accuracy, therefore shooting technique changed to maintain performance.
246 Davids et al. explained constraints to be boundaries that interact to limit the optimal movement state (6). 247 Constraints are characterised in to three groups. Individual where constraints are located inside the body. External 248 when constraints are in the environment and task where constraints are related to a skill or specific task (6). Latash 249 et al. argued that the body will adapt its output to compensate for the constraints imposed upon it, so that 250 movement is maintained as close to optimal as possible (15). Therefore, in the present study, the jump technique 251 variability is likely reflective of the body compensating for the constraints experienced. As no significant 252 difference was found between vertical jump exercise repetitions and jump height, it is argued that the jump 253 technique variability maintains jump performance.
255 The amount of technique variation differed between vertical jump exercises as DJ only experienced variation at 256 the knee joint, while RJ and SJ elicited variation at the hip, knee and ankle joints. This may be due to the level of 257 experience of a task. Comparison of expert and novice marksmen during a pistol target shooting task found experts 258 to have different angles at the shoulder and elbow but not the wrist during target shooting (21). However, novices 259 had variability at the wrist joints only (21). The authors suggested the experts were able to employ a flexible 260 degrees of freedom, (21). Degrees of freedom are the numerous independent ways an athlete can move (6), 261 therefore, experts employed a different degree of freedom to each individual target shot depending on the 262 constraints imposed upon them. The novices could not and used a more rigid degrees of freedom approach. This 263 phenomenon is known as functional variability allowing experts to use variable technique to maintain
287 exercise. This can be achieved by exposing a range of constrains on vertical jump exercises allowing athletes to 288 gain a wider experience of constraints that may affect them in competition. Incorporation of a range of vertical 289 jump exercises in training would also allow athletes to learn and utilise functional variability, so adaptation to 290 constraints is easier.
292 A more rigid vertical jump technique was used for the DJ, as there were fewer differences in kinematic measures. 293 This was due to participants not been able to attenuate impact forces upon landing, suggesting drop height was 294 too high. This highlights to the S&C coach that the athlete is not strong enough, and thus needs to develop strength. 295 Therefore, this is a method an S&C coach can use to identify if their athletes are strong enough to attenuate 296 landing force that may be experience in their sport.
298 Vertical jump kinematics differ between plyometric and ballistic exercise, thus there are different jump technique 299 of each exercise. The strength and conditioning coach should be aware of this as it may affect the method of 300 training the technical aspect of a vertical jump.
309 REFERENCES
311 1. Asmussen E and Bonde-Petersen F. Storage of Elastic Energy in Skeletal Muscles in Man. Acta 312 Physiologica Scandinavica 91: 385-392, 1974. 313 2. Baechle TR, Earle RW, Strength N, and Association C. Essentials of Strength Training and 314 Conditioning. Human Kinetics, 2000. 315 3. Batterham AM and Hopkins WG. Making meaningful inferences about magnitudes. Int J Sports Physiol 316 Perform 1: 50-57, 2006. 317 4. Bobbert MF, Gerritsen KG, Litjens MC, and Van Soest AJ. Why is countermovement jump height 318 greater than squat jump height? Med Sci Sports Exerc 28: 1402-1412, 1996. 319 5. Button C, MacLeod M, Sanders R, and Coleman S. Examining movement variability in the basketball 320 free-throw action at different skill levels. Res Q Exerc Sport 74: 257-269, 2003. 321 6. Davids K, Glazier P, Araujo D, and Bartlett R. Movement systems as dynamical systems: the functional 322 role of variability and its implications for sports medicine. Sports Med 33: 245-260, 2003. 323 7. Diallo O, Dore E, Duche P, and Van Praagh E. Effects of plyometric training followed by a reduced 324 training programme on physical performance in prepubescent soccer players. J Sports Med Phys Fitness 325 41: 342-348, 2001. 326 8. Domire ZJ and Challis JH. The influence of squat depth on maximal vertical jump performance. J Sports 327 Sci 25: 193-200, 2007. 328 9. Finni T, Komi PV, and Lepola V. In vivo human triceps surae and quadriceps femoris muscle function 329 in a squat jump and counter movement jump. Eur J Appl Physiol 83: 416-426, 2000. 330 10. Fleiss JL. The Design and Analysis of Clinical Experiments. Wiley, 1986. 331 11. Ford KR, Myer GD, and Hewett TE. Reliability of landing 3D motion analysis: implications for 332 longitudinal analyses. Med Sci Sports Exerc 39: 2021-2028, 2007. 333 12. Horita T, Komi PV, Hamalainen I, and Avela J. Exhausting stretch-shortening cycle (SSC) exercise 334 causes greater impairment in SSC performance than in pure concentric performance. Eur J Appl Physiol 335 88: 527-534, 2003. 336 13. Komi PV and Bosco C. Utilization of stored elastic energy in leg extensor muscles by men and women. 337 Med Sci Sports 10: 261-265, 1978. 338 14. Kotzamanidis C, Chatzopoulos D, Michailidis C, Papaiakovou G, and Patikas D. The effect of a 339 combined high-intensity strength and speed training program on the running and jumping ability of 340 soccer players. J Strength Cond Res 19: 369-375, 2005. 341 15. Latash ML, Scholz JP, and Schöner G. Motor Control Strategies Revealed in the Structure of Motor 342 Variability. Exercise and Sport Sciences Reviews 30: 26-31, 2002. 343 16. Mackala K, Stodolka J, Siemienski A, and Coh M. Biomechanical analysis of squat jump and 344 countermovement jump from varying starting positions. J Strength Cond Res 27: 2650-2661, 2013. 345 17. Malfait B, Sankey S, Firhad Raja Azidin RM, Deschamps K, Vanrenterghem J, Robinson MA, Staes F, 346 and Verschueren S. How reliable are lower-limb kinematics and kinetics during a drop vertical jump? 347 Med Sci Sports Exerc 46: 678-685, 2014. 348 18. Malisoux L, Francaux M, Nielens H, and Theisen D. Stretch-shortening cycle exercises: an effective 349 training paradigm to enhance power output of human single muscle fibers. J Appl Physiol (1985) 100: 350 771-779, 2006. 351 19. Matavulj D, Kukolj M, Ugarkovic D, Tihanyi J, and Jaric S. Effects of plyometric training on jumping 352 performance in junior basketball players. J Sports Med Phys Fitness 41: 159-164, 2001. 353 20. McBride JM, Kirby TJ, Haines TL, and Skinner J. Relationship between relative net vertical impulse 354 and jump height in jump squats performed to various squat depths and with various loads. Int J Sports 355 Physiol Perform 5: 484-496, 2010.
387 Table 1: Interclass correlation coefficient results
Drop Jump Rebound Jump Squat Jump
First ground contact 0.975 0.980 0.
Greatest jump depth 0.962 0.974 0.
Toe off 0.933 0.963 0.
Flexion range 0.986 0.927 0.
Extension range 0.979 0.799 0.
Flexion time 0.984 0.924 0.
Extension time 0.972 0.983 0.
Average angle velocity 0.885 0.923 0.
Jump height 0.985 0.985 0.
Technique maintains jump performance 19
Table 3: Exercise set results of the hip joint.
Data is given as mean (95% confidence intervals).
a = significantly different ( P < 0.05) from drop jump set 1
b = significantly different ( P < 0.05) from drop jump set 2
c = significantly different ( P < 0.05) from drop jump set 3
d = significantly different ( P < 0.05) from rebound jump set 1
e = significantly different ( P < 0.05) from rebound jump set 2
f = significantly different ( P < 0.05) from rebound jump set 3
Drop Jump Rebound Jump Squat Jump Set 1 Set 2 Set 3 Set 1 Set 2 Set 3 Set 1 Set 2 Set 3 Jump Height (cm) 42.5 47.6 49.4 53.5 c^ 49.3 c^ 52.2 a,b,c^ 62.5 a,b,c^ 56.3 a,b,c^ 60.7 a,b,c (31.3 - 48.8) (36.1 - 54.1) (37.4 - 56.3) (44.9 - 58.4) (40.2 - 54.5) (42.6 - 57.6) (52.9 - 67.9) (46.7 - 62.0) (51.2 - 66.3) First Ground Contact(degrees)
Greatest Jump Depth (degrees) 132.5 131.2 131.9 117.0 a^ 119.9 a,b,c^ 118.2 a,b,c^ 87.0 a,b,c,d,e,f^ 87.7 a,b,c,d,e,f^ 87.4 a,b,c,d,e,f (124.6 - 140.4) (121.2 - 141.2) (122.2 - 141.6) (101.7 - 132.2) (102.4 - 137.4) (92.9 - 143.6) (77.2 - 96.7) (70.4 - 105.1) (65.1 - 109.7) Toe Off (degrees) 168.5 167.0 166.9 162.6 a,b,c^ 162.6 a,b,c^ 162.3 a,b,c^ 156.7 a,b,c,d,e,f^ 156.8 a,b,c,d,e,f^ 157.8 a,b,c,d,e,f (164.5 - 172.4) (163.2 - 170.8) (163.5 - 170.3) (157.7 - 167.6) (155.9 - 169.3) (154.2 - 170.5) (152.9 - 160.4) (151.1 - 162.4) (150.8 - 164.8) Flexion Range (degrees) 18.3 22.8 21.5 39.8 a,c^ 33.4 a,b,c^ 37.1 a,c^ 66.0 a,b,c,d,e,f^ 60.8 a,b,c,d,e,f^ 62.5 a,b,c,d,e,f (11.7 - 24.8) (9.5 - 36.1) (11.1 - 31.8) (26.6 - 53.0) (16.7 - 50.1) (10.8 - 63.5) (55.2 - 76.9) (43.8 - 78.1) (37.8 - 87.1) Extension Range (degrees) 36.2 35.7 36.9 45.7 43.3 b,c^ 47.5 b,c^ 70.7 a,b,c,d,e,f^ 69.0 a,b,c,d,e,f^ 69.1 a,b,c,d,e,f (29.3 - 43.2) (24.5 - 46.8) (28.3 - 45.4) (34.2 - 57.2) (30.6 - 56.0) (25.9 - 69.1) (61.6 - 79.8) (54.7 - 83.4) (49.0 - 89.2) Flexion Time (seconds) 0.14 0.13 0.13 0.21 0.19 0.25 1.41 a,b,c,d,e,f^ 1.31 a,b,c,d,e,f^ 1.42 a,b,c,d,e,f (0.11 - 0.17) (0.10 - 0.16) (0.10 - 0.16) (0.14 - 0.28) (0.13 - 0.25) (0.13 - 0.37) (1.01 - 1.81) (0.84 - 1.78) (0.46 - 2.38) Extension Time (Seconds) 0.15 0.35 0.15 0.38 a,c^ 0.35 a,c^ 0.37 a,c^ 0.56 a,c,d,e,f^ 0.57 a,c,d,e,f^ 0.58 a,c,d,e,f (0.13 - 0.17) (-0.06 - 0.77) (0.12 - 0.18) (0.28 - 0.49) (0.23 - 0.47) (0.18 - 0.57) (0.46 - 0.65) (0.44 - 0.69) (0.41 - 0.75) Average Angular Velocity (degrees per second) 77.4 57.4 56.6 22.5 a,b,c^ 35.2 a,b,c,d^ 46.6 a,b,c^ 3.8 a,b,c,d,e,f^ 0.7 a,b,c,d,e,f^ 9.9 a,b,c,e (53.7 - 101.0) (32.2 - 82.4) 32.6 - 80.6) (7.69 - 37.3) (13.3 - 57.1) (-9.7 - 103.0) (0.1 - 7.5) (-5.1 - 6.4) (-17.8 - 37.5)
Technique maintains jump performance 20
Table 4: Exercise set results of the ankle joint.
a = significantly different ( P < 0.05) from drop jump set 1
b = significantly different ( P < 0.05) from drop jump set 2
c = significantly different ( P < 0.05) from drop jump set 3
d = significantly different ( P < 0.05) from rebound jump set 1
e = significantly different ( P < 0.05) from rebound jump set 2
f = significantly different ( P < 0.05) from rebound jump set 3
Drop Jump Rebound Jump Squat Jump Set 1 Set 2 Set 3 Set 1 Set 2 Set 3 Set 1 Set 2 Set 3 Jump Height (cm) 42.5^ 47.6^ 49.4^ 53.^ c (^) 49.3 c (^) 52.2 a,b,c (^) 62.5 a,b,c (^) 56.3 a,b,c (^) 60.7 a,b,c (31.3 - 48.8) (36.1 - 54.1) (37.4 - 56.3) (44.9 - 58.4) (40.2 - 54.5) (42.6 - 57.6) (52.9 - 67.9) (46.7 - 62.0) (51.2 - 66.3) First Ground Contact(degrees)
Greatest Jump Depth (degrees)
72.6 72.5 72.1 69.6 69.5 a,b,c^ 69.1 69.5 a,b,c,d,e,f^ 72.9 a,b,c,d,e,f^ 70.1 a,b,c,d,e,f
Toe Off (degrees)
112.0 111.2 111.1 110.8 111.2 112.3 112.8 d^ 111.0 114.4 c,d,e,f
Flexion Range (degrees)
41.4 40.9 41.6 39.8 41.9 40.2 57.2 a,b,c,d,e,f^ 49.9 b,d,e,f^ 53.0 a,b,c,d,e,f
Extension Range (degrees)
39.4 39.5 39.0 41.4 c^ 40.0 41.7 c^ 41.7 a,c^ 42.6 a,c^ 43.0 a,c
Flexion Time (seconds)
0.14 0.12 0.13 0.20 0.17 0.20 1.11 a,b,c,d,e,f^ 1.03 a,b,c,d,e,f^ 0.76 a,b,c,d,e,f
Extension Time (Seconds) 0.15 0.35 0.15 0.33 c^ 0.34 c^ 0.32 c^ 0.32 b,c^ 0.29 b,c^ 0.31 b,c (-0.75 - 0.45) (-0.26 - 0.96) (0.10 - 0.21) (0.29 - 0.37) (0.27 - 0.37) (0.21 - 0.43) (0.25 - 0.38) (0.12 - 0.47) (0.11 - 0.52) Average Angular Velocity (degrees per second)
Data is given as mean (95% confidence intervals).
