VERTICAL AND HORIZONTAL JUMP TESTS ARE ...

30 downloads 0 Views 498KB Size Report
on a Smith-machine (Technogym Equipment, Cesena, Italy). Athletes ..... Fry AC, Webber JM, Weiss LW, Harber MP, Vaczi M, and Pattison NA. Muscle. 305.
Journal of Strength and Conditioning Research Publish Ahead of Print DOI: 10.1519/JSC.0000000000000849

VERTICAL AND HORIZONTAL JUMP TESTS ARE STRONGLY ASSOCIATED WITH COMPETITIVE PERFORMANCE IN 100-M DASH EVENTS

D

Submission type: Research Note

TE

Irineu Loturco1 ( ), Lucas Adriano Pereira¹, Cesar Cavinato Cal Abad¹, Ricardo Antônio D’Angelo2, Victor Fernandes2, Katia Kitamura1, Ronaldo Kobal1, Fabio Yuzo Nakamura3

EP

1- NAR - Nucleus of High Performance in Sport, São Paulo, SP, Brazil 2- BMF – BOVESPA, Track & Field Club, São Paulo, SP, Brazil

C C

3- State University of Londrina, Londrina, PR, Brazil

A

Address for Correspondence:

Irineu Loturco ( ) NAR - Nucleus of High Performance in Sport.

Av. Padre José Maria, 555 - Santo Amaro, 04753-060 – São Paulo, SP, Brazil. Tel.: +55-11-3758-0918 E-mail: [email protected]

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

A

C C

EP

TE

D

Running head: JUMP TESTS ARE RELATED TO SPRINTING PERFORMANCE

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

1

ABSTRACT Fourteen male elite sprinters performed short-distance sprints and jump tests up to

3

18 days prior to 100-m dash competitions in track & field to determine if these tests are

4

associated with 100-m sprint times. Testing comprised squat jumps (SJ), countermovement

5

jumps (CMJ), horizontal jumps (HJ), maximum mean propulsive power relative to body

6

mass in loaded jump squats (MPPR) and a flying start 50-m sprint. Moderate associations

7

were found between speed tests and competitive 100-m times (r = 0.54, r = 0.61 and r =

8

0.66 for 10-, 30- and 50-m, respectively, P < 0.05). In addition, the MPPR was very largely

9

correlated with 100-m sprinting performance (r = 0.75, P < 0.01). The correlations of SJ,

10

CMJ and HJ with actual 100-m sprinting times amounted to -0.82, -0.85 and -0.81,

11

respectively. Due to their practicality, safeness and relationship with the actual times

12

obtained by top-level athletes in 100-m dash events, it is highly recommended that SJ,

13

CMJ, and HJ be regularly incorporated into elite sprint testing routines.

EP

TE

D

2

C C

14

Keywords: sprinting; Olympic athletes; muscle power; speed performance; track & field;

16

plyometrics

17 18 19 20

A

15

21 22 23 24

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

25

INTRODUCTION Performance variance in endurance running competitions is largely explained by the

27

triad maximal oxygen consumption, lactate threshold and running economy (19). For this

28

reason, training intervention studies have aimed at improving these variables in isolation or

29

in combination in order to enhance the athletes’ performance (31, 35). Surprisingly, to our

30

knowledge, there are no studies investigating the associations between physical or

31

physiological traits and competitive performance in sprinters, especially at the top-level.

32

Therefore, finding competitive performance correlates in a relatively homogeneous group

33

of sprinters is still a challenge. This is especially important at a time when upper human

34

performance in the 100-m sprint is being discussed, due to the astonishing times obtained

35

by both male and female athletes (16).

EP

TE

D

26

The sprint exercise is predominantly supplied by the anaerobic turnover of

37

adenosine triphosphate, with a significant drop in muscle pH and elevation in oxygen

38

consumption (2, 5). Anaerobic capacity, as measured by maximal oxygen deficit, partly

39

determines success in sprinting (29). However, this capacity has to be coupled with the

40

ability to increase the rate of anaerobic energy release (36) (i.e., anaerobic power).

41

Additionally, from a mechanical point of view, forces applied during the foot-ground

42

contact are related to the ability to reach top speeds (37). The combined metabolic and

44

A

43

C C

36

mechanical factors related to sprinting cannot be fully manifested without the large prevalence of fast twitch fibers in the lower limb muscles (22) and training-related neural

45

adaptations inherent to fast muscle activation (32). Similar characteristics appear to

46

determine performance in other explosive tasks, such as vertical jumps (VJ) (14, 24).

47

Therefore, positive associations are expected between jumping and sprinting abilities.

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

The scarce literature using less qualified sprinters evidenced that VJ and drop-jump

49

outcomes combined with the reactive strength index explained 89.6% of mean velocities in

50

several sprinting distances (34). In top-level sprinters, loaded and unloaded jumping

51

performances were highly correlated with the speed reached by elite sprinters in tests of up

52

to 50-m (13, 23).From these results, it was suggested that strength-power development is

53

important for athletes to achieve higher velocities over short-distances (23). It remains to be

54

established whether actual performance in 100-m and personal bests are related to jumping

55

ability. A recent editorial published in a sports science journal (11) claimed that regarding

56

monitoring tools, cost- and time-effective systems resulting in simple practices should be

57

sought rather than unnecessary complex systems. This is even more important in

58

developing countries with low resources to assess athletes in sports disciplines like track &

59

field sprinting.

EP

TE

D

48

Therefore, the purpose of this study was to ascertain whether, for top-level sprinters,

61

the actual performance in 100-m dash competitions is associated with neuromechanical

62

capacities measured by specific short-distance speed assessments and jump tests (in loaded

63

and unloaded conditions). Based on extensive published data confirming the strong

64

correlations between various neuromuscular measures and sprinting ability (12, 18, 20, 23,

65

26), we hypothesized that jump performance-related metrics would be significantly

67 68

A

66

C C

60

correlated with 100-m sprint times.

METHODS

69 70

Experimental Approach to the Problem

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

This study employed a cross-sectional correlational design to describe and explore

72

the relationships between speed and vertical jump test results (in loaded and unloaded

73

conditions), and actual 100-m dash performance in top-level sprinters. All sprinters were

74

familiar with the testing procedures, which were carried out during the competitive training

75

period, from 14 to 18 days prior to competitions where actual performance was measured.

76

Before the tests – executed on the same day – the athletes performed 20-min of general and

77

specific warm-up, including moderate running (10-min), active stretching (5-min) and

78

specific sprint drills (5-min). The order of the evaluations was as follows: test 1) squat

79

jumps (SJ) and countermovement jumps (CMJ); test 2) horizontal jumps (HJ); test3)

80

sprinting speed; and (90-min afterwards) test 4) mean propulsive power in jump squats. The

81

athletes received standard instructions on required pre-test behavior, including a minimum

82

of 8-h sleep, balanced nutrition and avoidance of beverages or food containing alcohol and

83

caffeine

EP

TE

D

71

85

Subjects

C C

84

Fourteen male elite sprinters (age: 24.9 ± 3.8 years; height: 178.7 ± 6.4 cm and body

87

mass: 77.8 ± 8.5 kg) volunteered to participate in the study. The sample comprised elite

88

athletes who participated in Olympic, Pan-American and South-American Games, with

89 90

A

86

personal records, on average, 7% longer than the men’s 100-m world-record (i.e., ≈ 10.28 ± 0.10 sec), thus attesting their high level of competitiveness. Athletes were briefed on the

91

experimental risks and benefits of the study, and signed a written informed consent

92

agreeing to take part. The study was approved by the local Ethics Committee.

93 94

Vertical jumps

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

VJs were assessed with the hands on the hips, using SJ and CMJ. For SJ, a static

96

position with a 90° knee-flexion angle was maintained for 2-sec before each attempt

97

without any preparatory movement. For CMJ, the sprinters performed a downward

98

movement followed by a complete extension of the lower limbs, freely determining the

99

amplitude of the countermovement. Five attempts at each jump were performed on a

100

contact platform (Smart-Jump; Fusion Sport, Brisbane, Australia), interspersed by 15-sec

101

intervals. The obtained flight time (t) was used to estimate the VJ height (h) (i.e., h = gt2/8).

102

The best attempt was retained for further analysis.

TE

103 104

D

95

Horizontal jumps

Sprinters performed the HJ starting from a standing position. They commenced the

106

jump by swinging their arms and bending their knees to provide maximal forward drive. A

107

take-off line was drawn on the ground, positioned immediately adjacent to a jump sandbox.

108

The jump-length measurement was determined using a metric tape measure (Lufkin,

109

L716MAGCME, Appex Group, USA), from the take-off line to the nearest point of landing

110

contact (i.e., back of the heels). Each athlete executed three attempts and the longest

111

distance was considered.

113 114

C C

A

112

EP

105

Jump squats

Mean propulsive power (MPP) was assessed in the jump squat exercise executed

115

on a Smith-machine (Technogym Equipment, Cesena, Italy). Athletes performed three

116

repetitions at maximal velocity for each load, starting at 40% body mass (BM); with loads

117

of 10% BM progressively added in each set until a decrease in MPP was observed. Subjects

118

executed a knee flexion until the thigh was parallel to the ground, then, following a

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

command, jumped as quickly as possible without their shoulder losing contact with the bar.

120

A 5-min interval was provided between sets. A linear transducer (T-Force, Ergotech,

121

Murcia, Spain) attached to the Smith-machine bar was used to obtain the MPP. The bar-

122

position data were sampled at 1,000 Hz using a PC (Toshiba, Tokyo, Japan). MPP rather

123

than peak power was used as Sanchez-Medina et al. (33) observed that these mechanical

124

values during the propulsive phase better reflect the differences in neuromuscular potential

125

between individuals. This method avoids underestimation of the true strength potential as

126

the higher the mean velocity (and lower the relative load), the greater the relative

127

contribution of the braking phase to the entire concentric time. The relative values of MPP

128

(MPPR) were obtained by dividing the higher values of MPP by the athletes’ BM (W/kg).

TE

D

119

130

EP

129

Speed testing

Sprinters performed two attempts at a flying start 50-m test to assess maximum

132

speed, with a 5-min interval between attempts. Four pairs of photocells (Smart-Speed,

133

Fusion Equipment, Brisbane, Australia) were positioned at distances of 0-, 10-, 30- and 50-

134

m. Athletes started each attempt 5-m behind the first photocell timing-gate, accelerating as

135

much as possible before crossing the starting line. The best 50-m performance was retained.

137 138

A

136

C C

131

Statistical Analyses Data are presented as mean ± standard deviation (SD). A Pearson product moment

139

correlation coefficient was used to analyze the relationships between jump and speed test

140

results and actual sprinters’ performances during competition. The threshold used to

141

qualitatively assess the correlations was based on Hopkins (17), using the following

142

criteria: 0.9 nearly perfect. Data normality was checked via the Shapiro-Wilk test. The

144

statistical significance level for all the analyses was set at P 0.05). The ICC for the jump squats, SJ,

151

CMJ, HJ and sprint times in 10-, 30- and 50-m were all > 0.90. The CV for all variables

152

analyzed was lower than 1%.

TE

150

Table 1 presents the means (SD) and the 95% confidence interval (CI) of the SJ,

154

CMJ, HJ, MPPR, and the sprint times at 10-, 30-, and 50-m and competitive 100-m dash

155

time. Table 2 shows the correlations between MPPR and short-distance sprint tests (10-,

156

30-, and 50-m) with actual 100-mperformance. Large associations were found between

157

speed tests and competitive 100-m times (r = 0.54, r = 0.61 and r = 0.66 for 10-, 30- and

158

50-m, respectively, P < 0.05). The MPPR was very largely correlated with 100-m sprinting

159

performance (r = 0.75, P < 0.01). Figure 1 depicts the correlations between SJ, CMJ, and

160

HJ and 100-m dash times. The jump tests were very largely associated with 100-m dash

162

C C

A

161

EP

153

performance (r = -0.82, r = -0.85 and r = -0.81 for SJ, CMJ, and HJ, respectively, P < 0.01).

163 164

***INSERT TABLE 1 HERE***

165 166

***INSERT TABLE 2 HERE***

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

167

***INSERT FIGURE 1 HERE***

168 169 170

DISCUSSION This study aimed to identify potential factors associated with sprinters’ performance

172

in official competitions. The main finding of this investigation was that, providing they are

173

executed few days (~2 weeks) before the competition, simple vertical and horizontal jump

174

test outcomes are very largely associated with actual 100-m dash performance in a sample

175

composed of male top-level sprinters. Moreover, the relative outputs of mean propulsive

176

power collected during jump squats demonstrated a correlation of -0.75 with actual speed

177

achieved by these athletes. Importantly, despite their apparent specificity, the “partial-

178

distance velocity tests” have only a moderate correlation with 100-m dash times.

EP

TE

D

171

The fact that practical jump tests are related to competitive sprinting performance is

180

very remarkable. Sprint training methods are full of technology, and the possibility of

181

monitoring sprinters’ athleticism using non-expensive tests especially favors the track &

182

field programs developed across emergent countries. Similarly, even the leading sports

183

nations may benefit from this method, as head coaches and strength & conditioning

184

specialists avoid assessing athletes’ speed close to competitions due to the high risk of

186

A

185

C C

179

injury involved in all-out tests. Despite the simplicity of the assessments, unloaded jump tests (SJ, CMJ and HJ)

187

had stronger associations with sprinting performance than MPPR. It must be mentioned that

188

the MPPR is measured “on the barbell” and it does not reflect the actual power output of a

189

given movement (8, 9, 27).Conversely, jump heights are measures able to express values

190

already corrected by the body weight. If during a VJ a subject jumps higher, he necessarily

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

produces higher values of relative force and relative power (N.kg-¹ and W.kg-¹,

192

respectively) than his weaker counterpart (3, 7). To achieve maximal height during a jump

193

attempt, the athlete’s center of mass needs to be as high as possible (in relation to the

194

ground), attaining the highest vertical velocity at the take-off (15). At this moment, the

195

subject follows a sequential pattern of lower limb segmental rotation, resulting in a great

196

amount of external forces, which are applied to overcome the inertia and accelerate the

197

body vertically (6). As the ground reaction force increases, the jump height increases.

198

Equally, the transition from lower to higher velocities (i.e., top-speed sprinting) results in

199

shorter support phase duration with a concomitant increase in vertical peak force (28). In

200

addition, the distances achieved during HJ are dependent on the athletes’ ability to transfer

201

the linear momentum of force directly from the ground to the peak horizontal acceleration

202

of the body’s centre of mass, which is also critical to break the inertia and attain high

203

velocities over short-distances (4, 18, 23). It is reasonable to assume that these mechanical

204

relative values tend to be more associated with the sprinters’ actual performance, since

205

during the competitions they have to push their bodies forward as rapidly as possible,

206

applying great amounts of force against the ground.

C C

EP

TE

D

191

The strong relationship between MPPR and 100-m sprint-times (r = -0.75) cannot

208

be overlooked. However, loaded jump testing may be potentially dangerous for athletes

209 210

A

207

when performed a short time before competitions (30). Differently from unloaded conditions (SJ and CMJ), jump squats using loads close to or higher than BM may

211

represent risks to joints and spine, by substantially increasing the ground reaction forces at

212

the landing moment (38). To some extent, the stronger values of correlation coefficients

213

(with 100-m times) presented by CMJ and SJ (r ≈ -0.84) when compared to loaded

214

conditions (r = -0.75, for MPPR) may be explained by the mechanical principles involved

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

in these assessments. The jump height is entirely related to the body’s vertical acceleration

216

and the acceleration is equal to force divided by mass (i.e., sprinter’s weight) (21). As a

217

result, for unloaded circumstances, higher jumping heights do not indicate only higher

218

values of relative force, but furthermore, indicate superior capacities to accelerate one’s

219

own body weight (1). Conversely, during jump squats, the power outputs (MPPR) are

220

directly collected from the barbell, which do not reflect the actual mechanical values (i.e.,

221

acceleration and velocity) of the athletes’ body centre of mass during a given movement

222

(10). It is conceivable that these mechanical differences may influence our findings,

223

resulting in stronger associations between sprinting times and unloaded vertical jumps.

224

Finally, the “loaded jump squat” evaluations are long lasting and involve expensive

225

equipment (i.e., linear position transducers), limiting their usefulness in the field, while

226

unloaded jump heights can be measured by simple “vertical jump-and-reach tests” (8).

227

Nevertheless, both unloaded and loaded jump squats are fed by the immediate energy

228

supply from the intramuscular phosphagens and require the neural control inherent to

229

ballistic movements that are also important in sprinting (32, 36).

C C

EP

TE

D

215

In addition to the aforementioned weaker correlations with actual sprint times, all-

231

out speed assessments also involve inherent risks (e.g., muscle and tendon injuries). It is

232

likely that closer proximity to competitions contributes to raising the fear presented by

233 234

A

230

coaches and athletes when executing speed tests, thus compromising their outcomes and reducing the correlations between “sprint-test-times” and “sprint-competition-times”. This

235

is due to the fact that top running speeds are related to high ground reaction forces rather

236

than more rapid repositioning of limbs in the air, meaning that the will to maximally engage

237

neuromuscular abilities is a prerequisite for achieving best performances in all-out speed

238

tests (37). Increases in the magnitude of the eccentric forces – and, consequently, in the

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

239

ground reaction forces -at the landing moment during the “loading stance phase” may result

240

in undesirable injury risks (25). This study is limited by the relatively small sample size. On the other hand, to our

242

knowledge this is the first study testing the relationship between unloaded and loaded jump

243

test performances and actual competitive performance in high caliber athletes. Hence,

244

interpretation of the results should take this important aspect into account.

D

241

To conclude, as long as they are executed few weeks before the competitions,

246

vertical and horizontal jump tests are directly related with 100-m dash times. The results

247

presented herein confirm that coaches are able to determine the readiness of their athletes

248

for 100-m performance by using simple SJ, CMJ and HJ. Short-distance speed test results

249

and jump squat power outputs (MPPR) have weaker correlations than unloaded jump

250

heights and distance (SJ, CMJ and HJ) with actual sprinting performance. Additionally,

251

these measurements involve a number of intrinsic problems, such as injury risks,

252

assessment time required and expensive equipment costs. Finally, with the stronger

253

correlations presented by practical unloaded jumps, these assessments should be considered

254

reliable enough to be related to actual sprinting times in highly competitive sprinters.

257 258

EP

C C

256

PRACTICAL APPLICATIONS

A

255

TE

245

From a practical perspective, simple jump tests can be used to assess the readiness

of the sprinters’ neuromuscular system to perform better during official competitions.

259

Anecdotally, assessing performance using these tests is a common practice in track & field;

260

however, it is possible that coaches are not aware of the strong and real potential of the

261

outcomes to forecast forthcoming competitive sprinting results. Therefore, we suggest that

262

measuring lower limb explosiveness by means of unloaded vertical jumps (SJ and CMJ)

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

263

and HJ may be useful in training and testing routines, due to their safeness and ability to

264

strongly explain 100-m dash performance in top-level athletes. Further longitudinal studies

265

are needed to fully elucidate the validity of jump tests in predicting changes in sprinters’

266

performance (i.e., longitudinal validity) due to training and the potential effects of tapering

267

and detraining periods on this relationship.

269

REFERENCES

270

1.

TE

Bodor M. Quadriceps protects the anterior cruciate ligament. J Orthop Res 19: 629633, 2001.

271 272

D

268

2.

Bogdanis GC, Nevill ME, Boobis LH, and Lakomy HK. Contribution of phosphocreatine and aerobic metabolism to energy supply during repeated sprint

274

exercise. J Appl Physiol 80: 876-884, 1996.

275

3.

EP

273

Bosco C, Luhtanen P, and Komi PV. A simple method for measurement of mechanical power in jumping. Eur J Appl Physiol Occup Physiol 50: 273-282,

277

1983.

278

4.

282

5.

Bundle MW, Hoyt RW, and Weyand PG. High-speed running performance: a new

A

281

Brechue WF, Mayhew JL, and Piper FC. Characteristics of sprint performance in college football players. J Strength Cond Res 24: 1169-1178, 2010.

279 280

C C

276

approach to assessment and prediction. J Appl Physiol 95: 1955-1962, 2003.

6.

Bunton EE, Pitney WA, Cappaert TA, and Kane AW. The role of limb torque,

283

muscle action and proprioception during closed kinetic chain rehabilitation of the

284

lower extremity. J Athl Train 28: 10-20, 1993.

285 286

7.

Copic N, Dopsaj M, Ivanovic J, Nesic G, and Jaric S. Body composition and muscle strength predictors of jumping performance: differences between elite female

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

287

volleyball competitors and nontrained individuals. J Strength Cond Res 28: 2709-

288

2716, 2014.

289

8.

Cormie P, McBride JM, and McCaulley GO. The influence of body mass on

290

calculation of power during lower-body resistance exercises. J Strength Cond Res

291

21: 1042-1049, 2007. 9.

Cormie P, McCaulley GO, Triplett NT, and McBride JM. Optimal loading for

D

292

maximal power output during lower-body resistance exercises. Med Sci Sports

294

Exerc 39: 340-349, 2007.

295

10.

TE

293

Cormie P, McGuigan MR, and Newton RU. Developing maximal neuromuscular power: Part 1-biological basis of maximal power production. Sports Med 41: 17-38,

297

2011. 11.

Physiol Perform 9: 741, 2014.

299 300

12.

Cronin JB and Hansen KT. Strength and power predictors of sports speed. J Strength Cond Res 19: 349-357, 2005.

301 302

Coutts AJ. In the Age of Technology, Occam's Razor Still Applies. Int J Sports

C C

298

EP

296

13.

Dobbs CW, Gill ND, Smart DJ, and McGuigan MR. Relationship between vertical and horizontal jump variables and muscular performance in athletes. J Strength

304

Cond Res in press, 2014.

305 306

A

303

14.

fiber characteristics of competitive power lifters. J Strength Cond Res 17: 402-410, 2003.

307 308

Fry AC, Webber JM, Weiss LW, Harber MP, Vaczi M, and Pattison NA. Muscle

15.

Harman EA, Rosenstein MT, Frykman PN, and Rosenstein RM. The effects of arms

309

and countermovement on vertical jumping. Med Sci Sports Exerc 22: 825-833,

310

1990.

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

311

16.

100m? Int J Sports Physiol Perform in press, 2014.

312 313

17.

Hopkins WG. A Scale of Magnitudes for Effect Statistics. A New View of Statistics, 2002.

314 315

Haugen T, Tonnessen E, and Seiler S. 9.58 and 10.49: Nearing the citius End for

18.

Hudgins B, Scharfenberg J, Triplett NT, and McBride JM. Relationship between jumping ability and running performance in events of varying distance. J Strength

317

Cond Res 27: 563-567, 2013. 19.

champions. J Physiol 586: 35-44, 2008.

319 320

Joyner MJ and Coyle EF. Endurance exercise performance: the physiology of

20.

TE

318

D

316

Kale M, Asci A, Bayrak C, and Acikada C. Relationships among jumping performances and sprint parameters during maximum speed phase in sprinters. J

322

Strength Cond Res 23: 2272-2279, 2009. 21.

1978, pp 22-24.

324 325

Kane JW and Sternheim MM. Vertical jumping, in: Physics. New York: Wiley,

22.

C C

323

EP

321

Korhonen MT, Cristea A, Alen M, Hakkinen K, Sipila S, Mero A, Viitasalo JT,

326

Larsson L, and Suominen H. Aging, muscle fiber type, and contractile function in

327

sprint-trained athletes. J Appl Physiol 101: 906-917, 2006.

329 330 331

23.

Loturco I, D'Angelo RA, Fernandes V, Gil S, Kobal R, Abad CCC, Kitamura K,

A

328

and Nakamura FY. Relationship between sprint ability and loaded/unloaded jump tests in elite sprinters. J Strength Cond Res in press, 2014.

24.

Loturco I, Ugrinowitsch C, Roschel H, Tricoli V, and Gonzalez-Badillo JJ. Training

332

at the optimum power zone produces similar performance improvements to

333

traditional strength training. J Sports Sci Med 12: 109-115, 2013.

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

334

25.

extremity biomechanics during the landing task. Michigan: ProQuest, 2007.

335 336

Mahdi HJ. Effects of plyometric training and augmented feedback on lower

26.

Markstrom JL and Olsson CJ. Countermovement jump peak force relative to body weight and jump height as predictors for sprint running performances:

338

(in)homogeneity of track and field athletes? J Strength Cond Res 27: 944-953,

339

2013.

340

27.

D

337

McBride JM, Haines TL, and Kirby TJ. Effect of loading on peak power of the bar, body, and system during power cleans, squats, and jump squats. J Sports Sci 29:

342

1215-1221, 2011. 28.

29.

Olesen HL, Raabo E, Bangsbo J, and Secher NH. Maximal oxygen deficit of sprint and middle distance runners. Eur J Appl Physiol Occup Physiol 69: 140-146, 1994.

346 347

EP

walking and running. Acta Physiol Scand 136: 217-227, 1989.

344 345

Nilsson J and Thorstensson A. Ground reaction forces at different speeds of human

30.

Patterson C, Raschner C, and Platzer HP. Power variables and bilateral force

C C

343

TE

341

348

differences during unloaded and loaded squat jumps in high performance alpine ski

349

racers. J Strength Cond Res 23: 779-787, 2009.

350

31.

A. Concurrent strength and endurance training effects on running economy in

353

A

351 352

master endurance runners. J Strength Cond Res 27: 2295-2303, 2013.

32.

356

Ross A, Leveritt M, and Riek S. Neural influences on sprint running: training

adaptations and acute responses. Sports Med 31: 409-425, 2001.

354 355

Piacentini MF, De Ioannon G, Comotto S, Spedicato A, Vernillo G, and La Torre

33.

Sanchez-Medina L, Perez CE, and Gonzalez-Badillo JJ. Importance of the propulsive phase in strength assessment. Int J Sports Med 31: 123-129, 2010.

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

357

34.

Smirniotou A, Katsikas C, Paradisis G, Argeitaki P, Zacharogiannis E, and Tziortzis

358

S. Strength-power parameters as predictors of sprinting performance. J Sports Med

359

Phys Fitness 48: 447-454, 2008.

360

35.

Stoggl T and Sperlich B. Polarized training has greater impact on key endurance variables than threshold, high intensity, or high volume training. Front Physiol 5:

362

33, 2014.

363

36.

D

361

Weyand PG, Lee CS, Martinez-Ruiz R, Bundle MW, Bellizzi MJ, and Wright S. High-speed running performance is largely unaffected by hypoxic reductions in

365

aerobic power. J Appl Physiol 86: 2059-2064, 1999.

366

37.

TE

364

Weyand PG, Sternlight DB, Bellizzi MJ, and Wright S. Faster top running speeds are achieved with greater ground forces not more rapid leg movements. J Appl

368

Physiol 89: 1991-1999, 2000.

369

38.

EP

367

Zink AJ, Perry AC, Robertson BL, Roach KE, and Signorile JF. Peak power, ground reaction forces, and velocity during the squat exercise performed at different

371

loads. J Strength Cond Res 20: 658-664, 2006.

373 374 375

A

372

C C

370

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

376

FIGURE LEGEND

377 378

Figure 1. Correlations between vertical (unloaded conditions) and horizontal jump tests

379

with actual 100-m dash times (**P< 0.01).

380

D

381 382

TE

383 384 385

EP

386 387 388

391 392 393

A

390

C C

389

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

Table 1. Descriptive analysis (mean, standard deviation [SD], and 95% confidence interval, [CI]) of the jumps in loaded and unloaded conditions, and short-distance sprint tests. CI (95%)

Mean ± SD

Lower

Upper

47.99 ± 3.68

45.86

50.11

CMJ (cm)

50.79 ± 4.16

48.38

53.19

HJ (m)

2.90 ± 0.11

2.84

2.96

10-m (s)

1.27 ± 0.02

1.26

30-m (s)

3.31 ± 0.04

3.29

D

SJ (cm)

1.28

TE

3.33

50-m (s)

5.20 ± 0.07

5.16

5.24

MPPR (W.kg )

13.46 ± 0.61

13.11

13.81

TIME (s)

10.49 ± 0.19

10.38

10.60

-1

EP

SJ = squat jump; CMJ = counter movement jump; MPPR = mean propulsive power

A

C C

relative to body mass; TIME = 100-m sprint time.

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

Table 2. Correlations between short-distance sprints (at 10-, 30- and 50-m), mean propulsive power relative to body mass (MPPR) and actual 100-m dash times (TIME). 10-m

50-m

MPPR

TIME

**

#

0.51

-0.54

*

0.54*

1

0.77

30-m

0.77**

1

0.84**

-0.62*

0.61*

50-m

0.51#

0.84**

1

-0.67**

0.66**

MPPR

-0.54*

-0.63*

-0.67**

1

-0.75**

TIME

0.54*

0.61*

0.66**

-0.75**

1

P = 0.06, *P < 0.05, **P< 0.01.

D

10-m

A

C C

EP

TE

#

30-m

Copyright Ó Lippincott Williams & Wilkins. All rights reserved.

D TE EP C C A Copyright Ó Lippincott Williams & Wilkins. All rights reserved.