Relationship between vertical jump height and ...

Journal of Strength and Conditioning Research Publish Ahead of Print DOI: 10.1519/JSC.0000000000001242

Relationship between vertical jump height and swimming start performance before and after an altitude training camp

Running head: Jump ability affects start performance

TE

D

Authors: Amador García-Ramos,1 Paulino Padial,1 Blanca de la Fuente,2 Javier ArgüellesCienfuegos,2 Juan Bonitch-Góngora,1 and Belén Feriche1

Institutional Affiliations: Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain 2 Spanish Sport Council, Sierra Nevada Training Centre 1

C C

ACKNOWLEDGMENTS

EP

Corresponding author: Belén Feriche. Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Ctra. de Alfacar, 18011 Granada (Spain). Tel.: +34958244381. Email: [email protected]

This study was supported by grants awarded by the Spanish Ministry of Science and Innovation (DEP2012-35774) and Ministry of Education, Culture and Sport (Predoctoral Grant FPU12/00360). The authors thank the swimmers and the coach (Albert Tubella) for

A

their collaboration and commitment to this study.

Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.

Jump ability affects start performance 1

ABSTRACT This study aimed (1) to analyze the development in squat jump height and swimming start performance following an altitude training camp, (2) to correlate jump height and swimming start performance before and after the altitude training period, and (3) to correlate the percent change in squat jump height with the percent change in swimming start performance. Fifteen

D

elite male swimmers from the Spanish Junior National Team (17.1 ± 0.8 years) were tested

TE

before and after a 17-day training camp at moderate altitude. The height reached in the squat jump exercise with additional loads of 0%, 25%, 50%, 75%, and 100% of swimmers’ pretest body weight and swimming start performance (time to 5, 10, and 15 meters) were the dependent variables analyzed. Significant increases in jump height (P < 0.05; ES: 0.35–0.48)

EP

and swimming start performance (P < 0.01; ES: 0.48–0.52) after the training period were observed. Start time had similar correlations with jump height before training (r = -0.56 to 0.77) to after training (r = -0.50 to -0.71). The change in squat jump height was inversely

C C

correlated with the change in start time at 5 meters (r = -0.47), 10 meters (r = -0.73), and 15 meters (r = -0.62). These results suggest that altitude training can be suitable to enhance explosive performance. The correlations obtained between the squat jump height and the start time in the raw and change scores confirm the relevance of possessing high levels of lower-

A

body muscular power to optimize swimming start performance.

Key Words: altitude training, lower-body muscular power, underwater undulatory swimming, OptoGait photoelectric system.



INTRODUCTION Altitude training is used in the preparation of elite and sub-elite athletes all over the world with the expectation of improving sea level performance (7). Swimmers are among the athletes that most frequently use altitude training (27). Although acute ascent to altitude deteriorates swimming performance, chronic exposure (3-4 weeks) may induce an

D

improvement in aerobic capacity, and consequently increase swimming performance upon

TE

returning to sea level (8,27). In this context, most of the scientific research conducted at altitude has been focused on the analysis of parameters related to endurance performance, such as the increase in hemoglobin mass or maximal oxygen uptake (8,16,27,29). Nowadays competitive pool events include races from 50 meters (lasting ≈ 21

EP

seconds) up to 1500 meters (lasting ≈ 15 minutes). While having a good aerobic capacity (e.g. maximal oxygen uptake) is paramount for longer distance performance, muscular power and anaerobic performance may be the determinants of success in the shorter distances

C C

(28,31). Endurance athletes are those who most commonly use altitude training to improve sea level performance (1,13,29). However, the sudden ascent to altitude has also been linked to an improvement in the performance of explosive actions (12,20,21). During an incremental loading test in the bench press exercise, Feriche et al. (12) reported an increase of 5.7% in

A

one-repetition maximum and a faster velocity for a given absolute load when the test was performed in hypobaric hypoxia compared to conditions of normoxia. These improvements could be caused by (a) an incremented ability of the organism to produce force promoted by the altitude exposure (17,24,30); (b) a reduced external resistance to the movement due to the air density decrease at altitude (20,21); and (c) a combination of both physiological and physical factors. Therefore it could be possible that training at altitude provides a favorable


Jump ability affects start performance 3 stimulus to the development of muscle power (12). Unfortunately, to the best of our knowledge, no study has addressed this issue yet. One of the important factors in swimming competitions, particularly in short events, is the ability to perform a good start (32). Overall swimming start performance, commonly defined as the time to 15 meters (2,33), is determined by a combination of the following variables: reaction time, force applied on the block, low drag while entering the water and

D

during the underwater glide, as well as underwater leg propulsion. Among them, the ability of

TE

exerting force against the starting block and the underwater leg propulsion phase could be improved with strength and power training (5,25,26). Therefore, whether altitude training plays an important role in the development of muscular power, it is possible that swimming start performance also can be enhanced following an altitude training program. This result

EP

would be especially beneficial for sprint swimmers (32,33).

Although it is known that an ascent to altitude improves the performance of explosive actions (12,21), there are few studies examining the effect of an altitude training camp on the

C C

performance of actions in which explosive force is paramount. Vertical jump height is probably the best predictor of lower-body muscular power (22). Therefore it would be interesting to examine the suitability of altitude training to enhance jump performance, as well as the performance of other physical actions that require the athlete to produce high rates

A

of force. In swimming, start performance is probably the part of the race most influenced by lower-body muscular power and strength (5,33). However, while significant correlations between jump performance and swimming start time have already been reported (33), the degree of accuracy in determining changes in swimming start performance through the changes in jump performance after a short-term training program has not been elucidated. In this context, the objective of the present study was threefold: (1) to analyze the development in squat jump height and swimming start performance after an altitude training camp, (2) to


Jump ability affects start performance 4 correlate jump height and swimming start performance before and after the altitude training period, and (3) to correlate the percent change in squat jump height with the percent change in swimming start performance following the altitude training camp.

METHODS Experimental approach to the problem

D

This study used a repeated-measures design to examine the effect of an altitude training camp

TE

on the development of squat jump height and swimming start performance in competitive young swimmers. Additionally a correlation analysis was conducted to examine the relationship between loaded and unloaded squat jump height with swimming start performance before and after the altitude training period. The accuracy of using changes in

EP

jump performance to determine changes in swimming start performance that occurred after the training program were also assessed through Pearson’s product-moment correlation. To this end, subjects took part in a training camp of 17 days at the High Performance

C C

Centre of Sierra Nevada (Spain) located at 2320 m asl. The swimming tests were conducted in the second (pretest) and sixteenth (postest) days. An undulatory swim start to a distance further than 15 meters was performed each day of testing. The dry land tests were randomly assigned to days 1 (pretest) and 15 (postest) for a group of swimmers, and to days 3 (pretest)

A

and 17 (postest) for the remaining swimmers. The squat jump exercise with additional loads of 0%, 25%, 50%, 75%, and 100% of swimmers’ pretest body weight (BW) was performed each day of dry land testing. The time to 5, 10, and 15 meters of the undulatory swimming start and the squat jump height were the dependent variables analyzed.



Subjects Fifteen male swimmers from the Spanish junior national team (age 17.1 ± 0.8 years, height 181.2 ± 6.5 cm, body mass 74.1 ± 8.0 kg) volunteered to participate in this study. Swimmers were in their competition period and had participated in national and international competitions for at least a year prior to the start of the study. None of the swimmers were

D

taking drugs, medication, or dietary supplements known to influence physical performance.

TE

All subjects were informed of the benefits and risks of the investigation prior to signing an informed consent form in accordance with the University of Granada Institutional Review Board and The Code of Ethics of the World Medical Association (Declaration of Helsinki).

Swimming test

EP

For swimmers under 18 years old, consent was obtained from their legal guardians.

After completing a standard warm–up based of their pre–race routine, swimmers were

C C

instructed to perform a kick start from a starting block (OMEGA OSB11) located at 0.70 meters from the water surface. A standardized starting procedure was used. Swimmers stood on the starting block and when ready were given the command ‘‘take your mark’’ before the starting device sounded. At the sound of the start, audible for the swimmers and visible as a

A

flashing light for the cameras, swimmers initiated the kick start followed by just underwater undulatory kicking (as used in butterfly stroke) at maximum velocity, until a distance further than 15 meters in order to ensure representative values of the time to 15 meters (2,14). The pool where the tests were conducted, had installed an official timing system (ALGE Swim Manager 2000) connected to a light device. Both systems were activated synchronously with the starting signal. This type of synchronization, used in paralympic competitions to provide a visual starting signal to deaf swimmers, was used in the present


Jump ability affects start performance 6 study to synchronize cameras with the acoustic starting signal. Three underwater cameras (Sensor SONY 1/4 EXView HAD CCD, shutter de 1/600, 100 fps) were set-up such that their optical axes were perpendicular to the direction of swimming at 5, 10, and 15 meters from the starting position. The time to 5, 10, and 15 meters were defined as the time elapsed from the starting signal until the swimmer’s head crossed the 5, 10, and 15 meter marks, respectively. The

D

analysis was made with the software Ultimate Pen (St Paul, Minnesota, USA) which allows

TE

the video image to be played while plotting the spatial references determined from the 2D reference system. The implementation of a routine (Script) in the Filemaker Pro v.12 software (Santa Clara, California, USA) enabled us to get the time code of the video image playing in with QuickTime Player v7 (Cupertino, California, USA) and set this time in its

Dry land test

EP

specific database field for further processing.

C C

After determining their height (Seca 202, Seca Ltd., Hamburg, Germany) and body mass (Tanita BC 418 segmental, Tokyo, Japan), swimmers completed a standardized warm-up based on jogging, joint mobility, dynamic stretching as well as six jumps without additional weight and one set of five jumps lifting 17 kg in the assessed exercise. Swimmers then

A

performed an incremental loading test using the squat jump exercise. First, they performed the unloaded squat jump (free weight) with a light bar (0.5 kg) over their shoulders (0% load), in order to keep the posture and the same body position as the rest of the jumps. After that, squat jumps with additional loads of 25%, 50% and 75%, and 100% of the swimmers’ pretest BW were lifted in a Smith machine (Technogym, Barcelona, Spain). Because the weight of the unloaded Smith machine bar was 17 kg, the swimmers with body mass < 68 kg performed their first set with a relative intensity higher than the 25% of BW. The progressive


Jump ability affects start performance 7 absolute loads used during the jumps with additional loads were 19.0 ± 1.9 kg (25.4 ± 0.7 %BW), 37.5 ± 4.1 kg (50.1 ± 0.3 %BW), 56.0 ± 6.2 kg (74.9 ± 0.3 %BW), and 74.9 ± 8.2 kg (100.1 ± 0.3 %BW). The same absolute loads for each subject were used in pretest and postest, allowing the assessment of the load-height relationship in identical loading conditions (18). Two repetitions were performed with each load. Recovery time was one min between attempts with the same load and five min between the different loads.

D

The movement commenced from a standing position with the knees and hips fully

TE

extended, feet approximately shoulder-width apart, and the barbell resting across the back at the level of the acromion. The swimmers then slowly crouched until the back of the thigh touched a rod on a tripod set at a knee angle of 90º (3). The knee angle was previously set with a manual goniometer. The subjects were instructed to maintain this position for two

EP

seconds before performing a purely concentric action in order to jump as high as possible (22). Subjects were encouraged to not perform any countermovement and to land with the feet and legs fully extended. When the jumps had not been properly executed, an additional

C C

jump was performed after the corresponding period of rest.

The OptoGait photoelectric system (Optogait 1.9, Microgate, Bolzano, Italy) was used to estimate squat jump height with a sample rate of 1000 Hz. This device has demonstrated strong concurrent validity with force plate measurements as well as excellent test-retest

A

reliability for the estimation of vertical jump height (15). Only the best jump executed at each load, identified according to the criterion of the highest jump height, was considered for subsequent analysis. In addition, an overall jump height value for each swimmer was calculated averaging the jump height values of each individual load ([0%BW + 25%BW + 50%BW + 75%BW +100%BW] / 5). Test–retest reliability for squat jump height at 0%BW (CV: 4.7%, ICC: 0.92) 25% BW (CV: 4.2%, ICC: 0.94), 50%BW (CV: 4.6%, ICC: 0.96), 75%BW (CV: 7.0%, ICC: 0.94), and 100%BW (CV: 10.5%, ICC: 0.94) was calculated.



Training prescription The swimmers completed the training programs prescribed by their coaches during the 17day training camp and the training load was monitored by training diaries. The main coach was responsible for filling in the training diary of each swimmer. On average, swimmers performed 25 pool sessions (mean ± standard deviations [SD]; duration: 119.8 ± 10.8 min,

D

CR-10 RPE [9]: 7.3 ± 0.9, and distance: 6696 ± 644 m) and 10 dry land sessions (4 circuits

TE

training and 6 strength-power training). The half-squat (3-4 sets of 6-8 repetitions with 7090% of BW and fast speed) and the lunge (3-4 sets of 6-12 repetitions with 30% of BW and moderate speed) were the lower limb exercises performed by the swimmers. A total of 240 min of the training period (on average a 13.4% of each pool training session) was dedicated

Statistical analysis

EP

to improving starting technique for swimming.

C C

Data are presented as mean ± SD. The normal distribution of the data was confirmed by the Shapiro-Wilk test (P > 0.05). A two-way (test [pretest and postest] x load [0%, 25%, 50%, 75%, and 100% of BW]) repeated measures ANOVA was used to compare squat jump height between the different tests performed. Another two-way (test [pretest and postest] x distance

A

[5, 10 and 15 meters]) repeated measures ANOVA was used to examine swimming start performance. When significant F values were achieved, pairwise differences between means were identified using Bonferroni post hoc procedures. The Greenhouse-Geisser correction was used when Mauchly’s test of sphericity was violated. The magnitude of the differences was expressed as a standardized mean difference (Cohen’s d effect size; ES). The criteria to interpret the magnitude of the ES were as follows: 2 = very large (19). Correlations between squat jump height


Jump ability affects start performance 9 and undulatory swimming start performance (time to 5, 10, and 15 meters) were quantified through Pearson’s linear correlation coefficient (r). Qualitative interpretations of the r coefficients as defined by Hopkins (19) (0–0.09 trivial; 0.1–0.29 small; 0.3–0.49 moderate; 0.5–0.69 large; 0.7–0.89 very large; 0.9–0.99 nearly perfect; 1 perfect) were provided for all significant correlations. All statistical tests were performed using the software package SPSS

TE

confidence interval at 95% is indicated when appropriate (95% CI).

D

(version 20.0: SPSS, Inc., Chicago, IL, USA). Significance was set at P < 0.05 and the

RESULTS Squat jump height

The two-way repeated measures ANOVA conducted in the present study to compare squat

EP

jump height revealed significant main effects for test (F[1,14] = 23.1, P < 0.001, η 2p = 0.622) and load (F[1.6,22.0] = 765.9, P < 0.001, η 2p = 0.982). The interaction between test and load did not reach statistical significance (F[4,56] = 1.826, P = 0.137, η 2p = 0.115). A significant

C C

increase in squat jump height after the altitude training period was observed (Table 1). The highest squat jump height was obtained without additional load, and significantly decreased

A

with each subsequent increase in load (P < 0.001 in all comparisons).

Table 1 about here

Swimming start performance The two-way repeated measures ANOVA conducted in the present study to examine swimming start performance revealed significant main effects for test (F[1,14] = 19.9, P