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The influence of ankle dorsiflexion on jumping capacity and the modified agility t-test performance a
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Juan J. Salinero , Javier Abian-Vicen , Juan Del Coso & Cristina González-Millán a
Sport Sciences Institute, Camilo José Cela University, Madrid, Spain Published online: 12 Mar 2013.
Click for updates To cite this article: Juan J. Salinero, Javier Abian-Vicen, Juan Del Coso & Cristina González-Millán (2014) The influence of ankle dorsiflexion on jumping capacity and the modified agility t-test performance, European Journal of Sport Science, 14:2, 137-143, DOI: 10.1080/17461391.2013.777797 To link to this article: http://dx.doi.org/10.1080/17461391.2013.777797
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European Journal of Sport Science, 2014 Vol. 14, No. 2, 137143, http://dx.doi.org/10.1080/17461391.2013.777797
ORIGINAL ARTICLE
The influence of ankle dorsiflexion on jumping capacity and the modified agility t-test performance
JUAN J. SALINERO, JAVIER ABIAN-VICEN, JUAN DEL COSO, & ´ LEZ-MILLA ´N CRISTINA GONZA
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Sport Sciences Institute, Camilo Jose´ Cela University, Madrid, Spain
Abstract Dorsiflexion sport shoes aim to increase jumping capacity and speed by means of a lower position of the heel in comparison with the forefoot, favouring additional stretching of the ankle plantar flexors. In previous studies, contradictory results have been found on the benefits of using this type of shoe. With the aim of comparing a dorsiflexion sport shoe model (DF) with a conventional sport shoe (CS), 41 participants performed a countermovement jump (CMJ) test and an agility test (MAT) with both models of shoe. There were no significant differences in the jump test [CS 35.3 cm (6.4) and DF 35.6 cm (6.4), P 0.05]. In the agility test, the conventional shoe obtained better results than the model with dorsiflexion with regard to time taken to complete the circuit [CS 6236 ms (540) and DF 6377 ms (507), P B0.05)]. In spite of producing pre-stretching of the plantar muscles, the DF sport shoes were not effective for improving either jump power or agility in a specific test.
Keywords: Sport shoe, jump, agility, dorsiflexion, muscle power
Introduction Sport shoes are a key component of physical performance in a variety of sport modalities. The commercial brands make increasing efforts to innovate and offer solutions which imply an advantage for the physical qualities involved in each sport. Lightness (Hilgers & Walther, 2011), shock absorption (Hreljac, 1998; Zhang, Clowers, Kohstall, & Yu, 2005), motion control (Rose, Birch, & Kuisma, 2011), ankle support (Brizuela, Llana, Ferrandis, & Garcia-Belenguer, 1997) or flexibility (Baudouin, Spampinato, Amos, & Morag, 2006; Stefanyshyn & Nigg, 2000) are aspects which have greater or lesser importance, depending on the sport modality. In those modalities, which require explosive actions, like jumping, the brands look for designs and supports in the sole and/or midsole which favour this jumping capacity to increase sport performance. On the one hand, there is the ‘plyometric training shoe’, which is constructed with a forefoot platform, elevating the forefoot above the heel. This shoe
eliminates the support of the heel and forces the calf muscles to support the full body load. The design purports to enhance the stretch reflex in the gastrocnemius and soleus muscles. Significant (P B 0.002) increases in electromyography activity were found in the medial gastrocnemius, tibialis anterior, gluteus maximus and erector spinae muscles when the subjects were wearing these shoes as compared to normal shoes (Frank, Baratta, Solomonow, Shilstone, & Riche, 2000). These products claim to increase speed, vertical jump height and range of motion; however, significant improvements have not been shown in jumping capacity in comparison with conventional shoes (Waggener, Gehlsen, & Massey, 1999). Furthermore, in a study which included 10 weeks training, jumping capacity and speed did not increase in comparison with conventional shoes, but the number of injuries did (Pethan, 1995; Porcari, Pethan, Ward, Fater, & Terry, 1996). On the other hand, a tendency has arisen to propitiate dorsiflexion of the foot which favours
Correspondence: Juan J. Salinero, Camilo Jose´ Cela University, Sport Sciences Institute, Castillo de alarco´n, 49, urb. villafranca del castillo, villanueva de la can˜ada, Madrid 28692, Spain. E-mail: [email protected] # 2013 European College of Sport Science
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muscular action to improve jumping capacity. By modifying the height of the heel and forefoot (with a lower heel, contrary to what is usual in a sport shoe), it is possible to increase the extension of the plantar flexors. Thus, it is claimed, explosive force, vertical jumping and speed are all augmented (SpringBoost, 2013). Dorsiflexion affects muscle recruitment and reorganizes the motor pattern (Bourgit, Millet, & Fuchslocher, 2008). The improvement in performance may be explained by dorsiflexion of the ankle that may induce a higher torque at the triceps surae level (Pinniger & Cresswell, 2007). The stretching of an activated muscle causes a transient increase in force during the stretch and sustained, residual force enhancement (RFE) after the stretch. The presence of RFE in human skeletal muscle under physiologically relevant conditions suggests that this characteristic may be exploited in functional tasks (Pinniger & Cresswell, 2007). Different studies have confirmed this influence on jump capacity. There are different models which exaggerate this tendency like the Meridian shoe which produces a marked dorsiflexion (108) and which has obtained contradictory results in different studies. In one study, there was an improvement in jump capacity and running speed which was greater than that achieved with conventional sport shoes after eight weeks training, (Kraemer, Ratamess, Volek, Mazzetti, & Gomez, 2000), while in a later study, these gains were not found (Ratamess et al., 2007). Several studies have contrasted conventional shoes with moderate dorsiflexion (48) and have found improvements with the dorsiflexion shoes (DF) in the countermovement jumping (CMJ), squat jumping and continuous jumping for 15 seconds (Faiss et al., 2010). In the same way, Larkins and Snabb (1999) compared shoes with a 3.58 dorsiflexion with conventional footwear and obtained significant improvements in jump capacity with the shoes that caused dorsiflexion of the ankle. However, in other studies, a greater improvement in jump capacity was achieved with conventional shoes (Ramsey, 1993). Other studies have analyzed the effect of training with this type of shoe for a period of several weeks, without finding evident improvements. No significant gains were found in jump capacity with DF compared with conventional sport shoes (CS) after a training period of 4 weeks (Cody, 1992), 8 weeks (Cook, Schultz, Omey, Wolfe, & Brunet, 1993) and 12 weeks (Nicopoulou, Tsitskaris, Toufas, Kellis, & Biternas, 1998; Tsitskaris, Nicopoulou, Mavromatis, & Kellis, 2001). Dorsiflexion can also modify the comfort perceived by the user since it changes foot position during standing and landing. However, research in
this area is still scarce. Shoe torsional stiffness or cushioning seems to be mechanical variables important for comfort of sport shoes (Miller, Nigg, Liu, Stefanyshyn, & Nurse, 2000). In some sports modalities, comfort is the highest priority that players want for their shoes (Hennig, 2011). So comfort must be a key factor when testing new shoes designs. In the light of these contradictory results, the purpose of the present study was to evaluate jump capacity and the time taken to complete an agility test with DF and with CS. As a complementary aspect, the users’ perceived comfort of the sport shoe was also evaluated. Materials and methods Subjects A total of 41 subjects took part in the study. All of them were male students at a Spanish Faculty of Physical Activity and Sports Sciences (2494.3 years; height 175.796.2 cm; weight 75.999.0 kg). Participants were fully informed of any risks and discomforts associated with the experiments before giving their informed written consent to participate. The study was approved by the Camilo Jose´ Cela University Review Board in accordance with the latest version of the Declaration of Helsinki. No participant suffered from any musculoskeletal anomaly which could have affected the results of the study. Participants were not informed about the characteristics of the sport shoes tested in the investigation so as not to influence their predisposition towards them. Instruments Sport shoes. Ten pairs of volleyball shoes were used with a dorsiflexion system of 28 (Springboost Model B-Voley, Switzerland) and 10 pairs of Kipsta indoor volleyball shoes, model 300 (Decathlon, France) were used as the CS. Apart from the characteristics of plantar flexion, the size, shape and fastenings (laces) of the shoes were similar (Figure 1). For the jump test, a Kistler QuattroJump† force platform (Kistler, Switzerland) was used with its associated software. For the agility test, five pairs of photoelectric cells (DSD Laser System, Spain) were used to record partial times. SportTest (DSD, Spain) software was used to record both partial times and the total time taken by each participant. Procedures The participants carried out a standard warm up consisting of 5 minutes of continuous running. Then they did a shuttle run over a distance of 30 m with
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Figure 1. Dorsiflexion shoe (right) and conventional sport shoe (left).
the following characteristics in each half: running raising heels to buttocks, skipping and jumping with the help of their arms every 10 m. They then moved to the jumping area. They had been familiarized with the type of jump to be performed prior to the test, which was a CMJ without the help of the arms. The whole procedure was performed with the participants wearing their own sport shoes. Then, participants wearing the corresponding sport shoes: DF or CS, performed three submaximal jumps and after 3 minutes rest, two maximal CMJs on the force platform, recording the best score achieved (Abian, Alegre, Lara, Rubio, & Aguado, 2008; Lara, Abian, Alegre, Jimenez, & Aguado, 2006). When the second attempt was better than the first, they were allowed a third attempt. The same protocol of instructions was given to the participants before each performance. After 5 minutes rest, they changed shoes and again performed two maximal jumps on the force platform. The order of the jumps, with DF or CS was randomized. After a 5-minute rest, they performed the agility test, which consisted of a modification of the t-test (MAT) proposed by Sassi et al. (2009). Participants had been familiarized with this test in a previous session. Figure 2 depicts the scheme of the MAT and the positioning of photocells.
The participants started from A, when they wanted, and ran forward to B to touch the top of the cone (15 cm high) with their right hand. Then they moved sideways without crossing their legs until they could touch the top of cone C with their left hand. They then moved sideways again to touch the top of cone D with their right hand. They then moved sideways again to touch the top of cone B with their left hand. Finally, they had to return to the starting point A as fast as possible running backwards. The total distance covered in each series was 20 m. Photoelectric cells were placed at the start line, 2 m away to evaluate acceleration speed without it being affected by their deceleration before point B and 1.5 m from point C to evaluate the time taken to change direction. All these photocells were placed at 90 cm over the floor. Photocells at points C and D were placed at 1 cm over the cone to ensure contact was made correctly. Only one test was performed with each model of sport shoe, with a 10-minute rest between them. The order in which the two types of sport shoe were used was randomized. At the end of all the tests, the subjects were asked about their comfort when wearing each type of shoe and required to assign a number from 0 to 10, where 10 was maximum comfort, this being a variation of the scales used in other studies on the comfort of sport shoes (Hagen, Ho¨mme, Umlauf, & Hennig, 2010; Milani, Hennig, & Lafortune, 1997)
Variables
Figure 2. Modified t-test and photocell placement.
The following variables were analyzed in the CMJ. Jump height (h) was calculated from the flight time with the following formula h g t2/8. Peak power (PP) was calculated from the integration of the forcetime curve during the push-off (PF) phase of the jump and normalized with the subject’s mass. At the instant at which PP was reached, force (Fpp) and the velocity of the centre of gravity (Vpp) were recorded. The following values were also determined: peak force generated during the PF; velocity at the end of the push-off at the moment of take-off (Vs); the position of the centre of gravity taking as a
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reference the initial position prior to the start of the push-off at the instant at which take off occurred (Hs), at the instant at which the centre of gravity was at the highest point in the flight phase (Hf) and at the instant at which contact was again made with the floor to absorb the impact (H1). During the absorption of the impact the second peak vertical force (F2) and the time which had passed since contact had been made with the floor until attainment of F2 were also analyzed (T2). The position of the centre of gravity was calculated with ‘Quattro Jump’ (V. 1.0.0.1) software with the double integration method (Lara et al., 2006; Linthorne, 2001). In the agility test, the total time taken to cover the circuit was analyzed as well as the partial times which can be seen in Figure 2: the acceleration phase (1), the change of direction from forward to left (2), the change of direction and sideways movement (braking, 3-start, 4), lateral movement (5), change of direction left to backwards (6) and backwards movement (7). Lastly, the users’ comfort with regard to the shoes was recorded.
Table I. Jump performance with DF and CS
Hf (cm) H (cm) PF (N) PP (W×kg 1) Vpp (m s 1) Fpp (N) Vs (m×s 1) Hs (cm) Hl (cm) F2 (N) T2 (s)
CS
DF
Effect size
P
46.6895.99 35.2896.42 18479307 50.8596.90 2.509.206 15349194 2.5990.25 12.6092.07 8.3292.39 466091822 0.06290.013
47.0796.03 35.6396.38 18669305 50.7597.09 2.479.213 15529190 2.5890.25 12.6892.11 8.1992.35 476991743 0.06590.016
0.07 0.05 0.06 0.01 0.15 0.09 0.04 0.04 0.05 0.06 0.23
0.234 0.432 0.279 0.737 0.019 0.091 0.912 0.858 0.719 0.611 0.151
Hf position of the centre of gravity at the highest point in the flight phase; h height of jump from flight time; PF peak force generated during the push-off; PP peak power; Vpp velocity of the centre of gravity at which PP was reached; Fpp force instant at which PP was reached; Vs velocity at the end of the push-off phase at the moment of take-off; Hs position of the centre of gravity at the instant that take off occurred; H1 position of the centre of gravity at the instant of landing; F2 second peak vertical force during landing; T2 time which had passed since contact with the floor until attainment of F2. Statistical significant differences (P B0.05) are in bold.
Agility test Statistical analyses The SPSS for Windows 19.0 statistical package was used to analyze the data. The normality of the variables was tested with the KolmogorovSmirnov test. All the variables presented normal distribution. Then, difference between means for both models of sport shoe was calculated with the t test for related samples, with the significance level set at PB0.05. Size effect was calculated according to the formula proposed by Glass, McGaw, and Smith (1981). The magnitude of the size effect was calculated using the scale of Cohen (1988); an effect size of 0.2 might be a small effect, around 0.5 a medium effect and over 0.8, a large effect.
The results obtained in the agility test, broken down by partial times and total time can be seen in Table II. In all the partial times, except the first and the last, the means obtained with CS tended to be better than with DF, with no significant differences in any of the partial times. If we analyze the total time taken to complete the test, we see a better result with CS (P 0.008). Effect size was low for all variables. Comfort assessment All the subjects gave an equal or lower score to the DF in comparison to CS. There is a difference of means of more than two points on the scale of 0 to 10 for CS compared with DF (7.8591.14 vs. 5.779 1.83; P 0.002; effect size 1.82, large).
Results Jump test
Discussion
Table I shows the results of the jump test using the force platform with each of the models of sport shoe. None of the variables analyzed with the force platform showed significant differences between either type of sport shoe (P0.05), with the exception of velocity at PP where a higher value was attained with CS. A tendency was observed for a greater force mean (P 0.091) to be obtained at the peak of power with DF. There were no differences in Hf and h, nor were there statistically significant differences in the impact absorption phase (F2 and T2). Effect size was low for all variables.
Dorsiflexion produces a modification in muscle activation (Bourgit et al., 2008; Frank et al., 2000), but this does not mean that this difference translates into an improvement in performance. These results contrast with previous studies which found improvements in jump capacity using sport shoes which increased dorsiflexion (Faiss et al., 2010; Larkins & Snabb, 1999). In both studies, they used larger degrees of dorsiflexion (48 and 3.58, respectively) than that employed in the present study (28) so that this may be the reason why there is a discrepancy in the results. In the study by Faiss et al.
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Table II. Modified t-test performance (ms) with DF and CS
Pt 1 acceleration Pt 2 change of direction (forward to left) Pt 3 sideways movement (braking) Pt 4 sideways movement (start) Pt 5 lateral movement Pt 6 change of direction (left to backwards) Pt 7 backwards movement Total time
CS (ms)
DF (ms)
Effect size
P
553958.1 11919130 3439112 5379136 11349118 19599216.1 5199115 62379540
551958.9 12159135 3459116.3 5839144 1150990.7 20159239 517989.2 63779508
0.03 0.18 0.02 0.34 0.14 0.26 0.02 0.26
0.774 0.074 0.932 0.104 0.368 0.055 0.929 0.008
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Pt partial time. Statistical significant differences (PB0.05) are in bold.
(2010), improvements of 4 cm were found in CMJ and higher values of velocity in the take-off with the sport shoes with dorsiflexion, but in our case, no significant differences were evident. Even velocity at PP was higher with the CS, although this did not translate into greater jump capacity. Another possible explanation for these discrepancies could be the adaptation to the shoes. In the study by Faiss et al. (2010), the subjects went through a period of acclimatization to the shoes, using them for 1 hour a day for 10 days, while in the present study, this was the first time that the participants had worn this model. It is probable that the special position adopted by the foot can negatively affect subjects who are not accustomed to using this type of shoe. However, in other studies, in which DF were used in training compared with conventional sport shoes, for a period of 412 weeks, jump capacity did not improve (Cody, 1992; Cook et al., 1993; Nicopoulou et al., 1998; Pethan, 1995; Porcari et al., 1996; Tsitskaris et al., 2001). In fact in other studies, there was a greater improvement in jump capacity with conventional shoes (Ramsey, 1993). According to biomechanical studies of the muscle, a pre-stretch of the ankle flexor or extensor musculature should increase the capacity of the muscle to generate strength. It has been seen that maximum voluntary torque in the plantar flexor muscles was also developed at 108 of plantar flexion and that it decreased sharply as ankle dorsiflexion increased to more than 58 (Marsh, Sale, McComas, & Quinlan, 1981). Equally in the triceps surae, the biarticular muscle pre-stretched with dorsiflexion, and it has been shown that with the knee bent, the optimum length for torque development corresponded to almost full dorsiflexion of the ankle. Similar results were obtained with the knee extended (Sale, Quinlan, Marsh, McComas, & Belanger, 1982). This improvement was only evident at the level of the extensor musculature of the ankle, not affecting the ankle position in knee extensor peak torque in either ankle position, dorsiflexion or plantar flexion (Croce, Miller, & St Pierre, 2000).
With regard to the agility test, the sport shoes which increased dorsiflexion showed a significantly poorer performance overall. If we look at the partial times in detail, we can see a tendency towards worse results with DF in the partial times, which included a change of direction (P 0.074 and P 0.055), appearing to indicate that dorsiflexion hinders movements, which imply a quick change of direction, perhaps based on the fact that stretching the muscle caused an increase in both the contraction and halfrelaxation times (Sale et al., 1982). The results obtained in both tests cast doubt on the benefits of moderate dorsiflexion for improving performance in modalities which require jumping capacity or covering short distances, as in the case of volleyball. Furthermore, in the comfort test, there was a notable difference in favour of the CS, an aspect to be taken into account as a drawback of the DF. It would be interesting to extend this study to different degrees of dorsal and plantar flexion to get a more in-depth perspective of their influence on sport performance. Conclusions Several commercial brands have developed shoes that increase ankle dorsiflexion in an attempt to increase the extension of the plantar flexor muscles thereby improving muscle contraction and jump performance. However, we have found that our active participants had a similar jump performance with CS and with DF and that their agility decreased slightly with the use of DF. We recommend using CS during sport activities that involve repeated jumps and actions demanding agility. References Abian, J., Alegre, L. M., Lara, A. J., Rubio, J. A., & Aguado, X. (2008). Landing differences between men and women in a maximal vertical jump aptitude test. Journal of Sports Medicine and Physical Fitness, 48(3), 305310. PMID: 18974715. Baudouin, A., Spampinato, J., Amos, M., & Morag, E. (2006). The relationship between forefoot flexibility and in-shoe measurements. In International Society of Biomechanics in Sports, Proceedings of XXIV International Symposium on Biomechanics
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Linthorne, N. P. (2001). Analysis of standing vertical jumps using a force platform. American Journal of Physics, 69(11), 1198 1204. doi:10.1119/1.1397460 Marsh, E., Sale, D., McComas, A. J., & Quinlan, J. (1981). Influence of joint position on ankle dorsiflexion in humans. Journal of Applied Physiology, 51(1), 160167. Milani, T. L., Hennig, E. M., & Lafortune, M. A. (1997). Perceptual and biomechanical variables for running in identical shoe constructions with varying midsole hardness. Clinical Biomechanics, 12(5), 294300. doi:10.1016/S0268-0033(97) 00008-9 Miller, J. E., Nigg, B. M., Liu, W., Stefanyshyn, D. J., & Nurse, M. A. (2000). Influence of foot, leg and shoe characteristics on subjective comfort. Foot & Ankle International, 21(9), 759767. Nicopoulou, M. D., Tsitskaris, G. K., Toufas, N. K., Kellis, S. E., & Biternas, A. G. (1998). The evaluation of the influence of strength shoe as an effective supplement to a twelve week training program on the vertical jump improvement of male and female Greek basketball players. Journal of Sports Science & Coaching, 3(2), 712. Pethan, S. M. (1995). Effects of training in strength shoes(TM) on speed, jumping ability, and calf girth (Thesis). University of Oregon, Eugene. Retrieved from http://search.ebscohost./login. aspx?direct true&db s3h&AN SPH377621&site ehost-live. Available from EBSCOhost s3h database. Pinniger, G. J., & Cresswell, A. G. (2007). Residual force enhancement after lengthening is present during submaximal plantar flexion and dorsiflexion actions in humans. Journal of Applied Physiology, 102(1), 1825. doi:10.1152/japplphysiol. 00565.2006 Porcari, J. P., Pethan, S. M., Ward, K., Fater, D., & Terry, L. (1996). Effects of training in strength shoes on 40-yard dash time, jumping ability, and calf girth. Journal of Strength and Conditioning Research, 10(2), 120123. Ramsey, J. K. (1993). Influence of the strength shoe and three plyometric drills on the strength, velocity, and jumping ability of high school football players (Thesis). University of Oregon, Eugene. Retrieved from http://search.ebscohost.com/login.aspx?direct true&db s3h&AN SPH324965&site ehost-live. Available from EBSCOhost s3h database. Ratamess, N. A., Kraemer, W. J., Volek, J. S., French, D. N., Rubin, M. R., Gomez, A. L., & . . . Maresh, C. M. (2007). The effects of ten weeks of resistance and combined plyometric/ sprint training with the Meridian Elyte athletic shoe on muscular performance in women. Journal of Strength and Conditioning Research, 21(3), 882887. doi:R-50512 [pii] 10.1519/R-50512.1 Rose, A., Birch, I., & Kuisma, R. (2011). Effect of motion control running shoes compared with neutral shoes on tibial rotation during running. Physiotherapy, 97(3), 250255. doi:10.1016/ j.physio.2010.08.013 Sale, D., Quinlan, J., Marsh, E., McComas, A. J., & Belanger, A. Y. (1982). Influence of joint position on ankle plantarflexion in humans. Journal of Applied Physiology, 52(6), 16361642. Sassi, R. H., Dardouri, W., Yahmed, M. H., Gmada, N., Mahfoudhi, M. E., & Gharbi, Z. (2009). Relative and absolute reliability of a modified agility t-test and its relationship with vertical jump and straight sprint. Journal of Strength and Conditioning Research, 23(6), 16441651. doi:10.1519/ JSC.0b013e3181b425d2 SpringBoost. (2013). DORSI technologyTM. Retrieved from http:// springboost.com/en/dorsiflexion/performance-shoes_benefits. html Stefanyshyn, D. J., & Nigg, B. M. (2000). Influence of midsole bending stiffness on joint energy and jump height performance. Medicine and Science in Sports and Exercise, 32(2), 471476. doi:10.1097/00005768-200002000-00032
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Tsitskaris, G., Nicopoulou, M., Mavromatis, G., & Kellis, S. (2001). The influence of strength shoe as an effective supplement to a twelve week training program on the vertical jump improvement of male and female basketball players. Exercise and Society: Journal of Sport Sciences, 27, 4453. Waggener, W. R., Gehlsen, G. M., & Massey, J. C. (1999). The effects of a plyometric training shoe on vertical jump height,
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European Journal of Sport Science Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tejs20
The influence of ankle dorsiflexion on jumping capacity and the modified agility t-test performance a
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Juan J. Salinero , Javier Abian-Vicen , Juan Del Coso & Cristina González-Millán a
Sport Sciences Institute, Camilo José Cela University, Madrid, Spain Published online: 12 Mar 2013.
Click for updates To cite this article: Juan J. Salinero, Javier Abian-Vicen, Juan Del Coso & Cristina González-Millán (2014) The influence of ankle dorsiflexion on jumping capacity and the modified agility t-test performance, European Journal of Sport Science, 14:2, 137-143, DOI: 10.1080/17461391.2013.777797 To link to this article: http://dx.doi.org/10.1080/17461391.2013.777797
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European Journal of Sport Science, 2014 Vol. 14, No. 2, 137143, http://dx.doi.org/10.1080/17461391.2013.777797
ORIGINAL ARTICLE
The influence of ankle dorsiflexion on jumping capacity and the modified agility t-test performance
JUAN J. SALINERO, JAVIER ABIAN-VICEN, JUAN DEL COSO, & ´ LEZ-MILLA ´N CRISTINA GONZA
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Sport Sciences Institute, Camilo Jose´ Cela University, Madrid, Spain
Abstract Dorsiflexion sport shoes aim to increase jumping capacity and speed by means of a lower position of the heel in comparison with the forefoot, favouring additional stretching of the ankle plantar flexors. In previous studies, contradictory results have been found on the benefits of using this type of shoe. With the aim of comparing a dorsiflexion sport shoe model (DF) with a conventional sport shoe (CS), 41 participants performed a countermovement jump (CMJ) test and an agility test (MAT) with both models of shoe. There were no significant differences in the jump test [CS 35.3 cm (6.4) and DF 35.6 cm (6.4), P 0.05]. In the agility test, the conventional shoe obtained better results than the model with dorsiflexion with regard to time taken to complete the circuit [CS 6236 ms (540) and DF 6377 ms (507), P B0.05)]. In spite of producing pre-stretching of the plantar muscles, the DF sport shoes were not effective for improving either jump power or agility in a specific test.
Keywords: Sport shoe, jump, agility, dorsiflexion, muscle power
Introduction Sport shoes are a key component of physical performance in a variety of sport modalities. The commercial brands make increasing efforts to innovate and offer solutions which imply an advantage for the physical qualities involved in each sport. Lightness (Hilgers & Walther, 2011), shock absorption (Hreljac, 1998; Zhang, Clowers, Kohstall, & Yu, 2005), motion control (Rose, Birch, & Kuisma, 2011), ankle support (Brizuela, Llana, Ferrandis, & Garcia-Belenguer, 1997) or flexibility (Baudouin, Spampinato, Amos, & Morag, 2006; Stefanyshyn & Nigg, 2000) are aspects which have greater or lesser importance, depending on the sport modality. In those modalities, which require explosive actions, like jumping, the brands look for designs and supports in the sole and/or midsole which favour this jumping capacity to increase sport performance. On the one hand, there is the ‘plyometric training shoe’, which is constructed with a forefoot platform, elevating the forefoot above the heel. This shoe
eliminates the support of the heel and forces the calf muscles to support the full body load. The design purports to enhance the stretch reflex in the gastrocnemius and soleus muscles. Significant (P B 0.002) increases in electromyography activity were found in the medial gastrocnemius, tibialis anterior, gluteus maximus and erector spinae muscles when the subjects were wearing these shoes as compared to normal shoes (Frank, Baratta, Solomonow, Shilstone, & Riche, 2000). These products claim to increase speed, vertical jump height and range of motion; however, significant improvements have not been shown in jumping capacity in comparison with conventional shoes (Waggener, Gehlsen, & Massey, 1999). Furthermore, in a study which included 10 weeks training, jumping capacity and speed did not increase in comparison with conventional shoes, but the number of injuries did (Pethan, 1995; Porcari, Pethan, Ward, Fater, & Terry, 1996). On the other hand, a tendency has arisen to propitiate dorsiflexion of the foot which favours
Correspondence: Juan J. Salinero, Camilo Jose´ Cela University, Sport Sciences Institute, Castillo de alarco´n, 49, urb. villafranca del castillo, villanueva de la can˜ada, Madrid 28692, Spain. E-mail: [email protected] # 2013 European College of Sport Science
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muscular action to improve jumping capacity. By modifying the height of the heel and forefoot (with a lower heel, contrary to what is usual in a sport shoe), it is possible to increase the extension of the plantar flexors. Thus, it is claimed, explosive force, vertical jumping and speed are all augmented (SpringBoost, 2013). Dorsiflexion affects muscle recruitment and reorganizes the motor pattern (Bourgit, Millet, & Fuchslocher, 2008). The improvement in performance may be explained by dorsiflexion of the ankle that may induce a higher torque at the triceps surae level (Pinniger & Cresswell, 2007). The stretching of an activated muscle causes a transient increase in force during the stretch and sustained, residual force enhancement (RFE) after the stretch. The presence of RFE in human skeletal muscle under physiologically relevant conditions suggests that this characteristic may be exploited in functional tasks (Pinniger & Cresswell, 2007). Different studies have confirmed this influence on jump capacity. There are different models which exaggerate this tendency like the Meridian shoe which produces a marked dorsiflexion (108) and which has obtained contradictory results in different studies. In one study, there was an improvement in jump capacity and running speed which was greater than that achieved with conventional sport shoes after eight weeks training, (Kraemer, Ratamess, Volek, Mazzetti, & Gomez, 2000), while in a later study, these gains were not found (Ratamess et al., 2007). Several studies have contrasted conventional shoes with moderate dorsiflexion (48) and have found improvements with the dorsiflexion shoes (DF) in the countermovement jumping (CMJ), squat jumping and continuous jumping for 15 seconds (Faiss et al., 2010). In the same way, Larkins and Snabb (1999) compared shoes with a 3.58 dorsiflexion with conventional footwear and obtained significant improvements in jump capacity with the shoes that caused dorsiflexion of the ankle. However, in other studies, a greater improvement in jump capacity was achieved with conventional shoes (Ramsey, 1993). Other studies have analyzed the effect of training with this type of shoe for a period of several weeks, without finding evident improvements. No significant gains were found in jump capacity with DF compared with conventional sport shoes (CS) after a training period of 4 weeks (Cody, 1992), 8 weeks (Cook, Schultz, Omey, Wolfe, & Brunet, 1993) and 12 weeks (Nicopoulou, Tsitskaris, Toufas, Kellis, & Biternas, 1998; Tsitskaris, Nicopoulou, Mavromatis, & Kellis, 2001). Dorsiflexion can also modify the comfort perceived by the user since it changes foot position during standing and landing. However, research in
this area is still scarce. Shoe torsional stiffness or cushioning seems to be mechanical variables important for comfort of sport shoes (Miller, Nigg, Liu, Stefanyshyn, & Nurse, 2000). In some sports modalities, comfort is the highest priority that players want for their shoes (Hennig, 2011). So comfort must be a key factor when testing new shoes designs. In the light of these contradictory results, the purpose of the present study was to evaluate jump capacity and the time taken to complete an agility test with DF and with CS. As a complementary aspect, the users’ perceived comfort of the sport shoe was also evaluated. Materials and methods Subjects A total of 41 subjects took part in the study. All of them were male students at a Spanish Faculty of Physical Activity and Sports Sciences (2494.3 years; height 175.796.2 cm; weight 75.999.0 kg). Participants were fully informed of any risks and discomforts associated with the experiments before giving their informed written consent to participate. The study was approved by the Camilo Jose´ Cela University Review Board in accordance with the latest version of the Declaration of Helsinki. No participant suffered from any musculoskeletal anomaly which could have affected the results of the study. Participants were not informed about the characteristics of the sport shoes tested in the investigation so as not to influence their predisposition towards them. Instruments Sport shoes. Ten pairs of volleyball shoes were used with a dorsiflexion system of 28 (Springboost Model B-Voley, Switzerland) and 10 pairs of Kipsta indoor volleyball shoes, model 300 (Decathlon, France) were used as the CS. Apart from the characteristics of plantar flexion, the size, shape and fastenings (laces) of the shoes were similar (Figure 1). For the jump test, a Kistler QuattroJump† force platform (Kistler, Switzerland) was used with its associated software. For the agility test, five pairs of photoelectric cells (DSD Laser System, Spain) were used to record partial times. SportTest (DSD, Spain) software was used to record both partial times and the total time taken by each participant. Procedures The participants carried out a standard warm up consisting of 5 minutes of continuous running. Then they did a shuttle run over a distance of 30 m with
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Figure 1. Dorsiflexion shoe (right) and conventional sport shoe (left).
the following characteristics in each half: running raising heels to buttocks, skipping and jumping with the help of their arms every 10 m. They then moved to the jumping area. They had been familiarized with the type of jump to be performed prior to the test, which was a CMJ without the help of the arms. The whole procedure was performed with the participants wearing their own sport shoes. Then, participants wearing the corresponding sport shoes: DF or CS, performed three submaximal jumps and after 3 minutes rest, two maximal CMJs on the force platform, recording the best score achieved (Abian, Alegre, Lara, Rubio, & Aguado, 2008; Lara, Abian, Alegre, Jimenez, & Aguado, 2006). When the second attempt was better than the first, they were allowed a third attempt. The same protocol of instructions was given to the participants before each performance. After 5 minutes rest, they changed shoes and again performed two maximal jumps on the force platform. The order of the jumps, with DF or CS was randomized. After a 5-minute rest, they performed the agility test, which consisted of a modification of the t-test (MAT) proposed by Sassi et al. (2009). Participants had been familiarized with this test in a previous session. Figure 2 depicts the scheme of the MAT and the positioning of photocells.
The participants started from A, when they wanted, and ran forward to B to touch the top of the cone (15 cm high) with their right hand. Then they moved sideways without crossing their legs until they could touch the top of cone C with their left hand. They then moved sideways again to touch the top of cone D with their right hand. They then moved sideways again to touch the top of cone B with their left hand. Finally, they had to return to the starting point A as fast as possible running backwards. The total distance covered in each series was 20 m. Photoelectric cells were placed at the start line, 2 m away to evaluate acceleration speed without it being affected by their deceleration before point B and 1.5 m from point C to evaluate the time taken to change direction. All these photocells were placed at 90 cm over the floor. Photocells at points C and D were placed at 1 cm over the cone to ensure contact was made correctly. Only one test was performed with each model of sport shoe, with a 10-minute rest between them. The order in which the two types of sport shoe were used was randomized. At the end of all the tests, the subjects were asked about their comfort when wearing each type of shoe and required to assign a number from 0 to 10, where 10 was maximum comfort, this being a variation of the scales used in other studies on the comfort of sport shoes (Hagen, Ho¨mme, Umlauf, & Hennig, 2010; Milani, Hennig, & Lafortune, 1997)
Variables
Figure 2. Modified t-test and photocell placement.
The following variables were analyzed in the CMJ. Jump height (h) was calculated from the flight time with the following formula h g t2/8. Peak power (PP) was calculated from the integration of the forcetime curve during the push-off (PF) phase of the jump and normalized with the subject’s mass. At the instant at which PP was reached, force (Fpp) and the velocity of the centre of gravity (Vpp) were recorded. The following values were also determined: peak force generated during the PF; velocity at the end of the push-off at the moment of take-off (Vs); the position of the centre of gravity taking as a
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reference the initial position prior to the start of the push-off at the instant at which take off occurred (Hs), at the instant at which the centre of gravity was at the highest point in the flight phase (Hf) and at the instant at which contact was again made with the floor to absorb the impact (H1). During the absorption of the impact the second peak vertical force (F2) and the time which had passed since contact had been made with the floor until attainment of F2 were also analyzed (T2). The position of the centre of gravity was calculated with ‘Quattro Jump’ (V. 1.0.0.1) software with the double integration method (Lara et al., 2006; Linthorne, 2001). In the agility test, the total time taken to cover the circuit was analyzed as well as the partial times which can be seen in Figure 2: the acceleration phase (1), the change of direction from forward to left (2), the change of direction and sideways movement (braking, 3-start, 4), lateral movement (5), change of direction left to backwards (6) and backwards movement (7). Lastly, the users’ comfort with regard to the shoes was recorded.
Table I. Jump performance with DF and CS
Hf (cm) H (cm) PF (N) PP (W×kg 1) Vpp (m s 1) Fpp (N) Vs (m×s 1) Hs (cm) Hl (cm) F2 (N) T2 (s)
CS
DF
Effect size
P
46.6895.99 35.2896.42 18479307 50.8596.90 2.509.206 15349194 2.5990.25 12.6092.07 8.3292.39 466091822 0.06290.013
47.0796.03 35.6396.38 18669305 50.7597.09 2.479.213 15529190 2.5890.25 12.6892.11 8.1992.35 476991743 0.06590.016
0.07 0.05 0.06 0.01 0.15 0.09 0.04 0.04 0.05 0.06 0.23
0.234 0.432 0.279 0.737 0.019 0.091 0.912 0.858 0.719 0.611 0.151
Hf position of the centre of gravity at the highest point in the flight phase; h height of jump from flight time; PF peak force generated during the push-off; PP peak power; Vpp velocity of the centre of gravity at which PP was reached; Fpp force instant at which PP was reached; Vs velocity at the end of the push-off phase at the moment of take-off; Hs position of the centre of gravity at the instant that take off occurred; H1 position of the centre of gravity at the instant of landing; F2 second peak vertical force during landing; T2 time which had passed since contact with the floor until attainment of F2. Statistical significant differences (P B0.05) are in bold.
Agility test Statistical analyses The SPSS for Windows 19.0 statistical package was used to analyze the data. The normality of the variables was tested with the KolmogorovSmirnov test. All the variables presented normal distribution. Then, difference between means for both models of sport shoe was calculated with the t test for related samples, with the significance level set at PB0.05. Size effect was calculated according to the formula proposed by Glass, McGaw, and Smith (1981). The magnitude of the size effect was calculated using the scale of Cohen (1988); an effect size of 0.2 might be a small effect, around 0.5 a medium effect and over 0.8, a large effect.
The results obtained in the agility test, broken down by partial times and total time can be seen in Table II. In all the partial times, except the first and the last, the means obtained with CS tended to be better than with DF, with no significant differences in any of the partial times. If we analyze the total time taken to complete the test, we see a better result with CS (P 0.008). Effect size was low for all variables. Comfort assessment All the subjects gave an equal or lower score to the DF in comparison to CS. There is a difference of means of more than two points on the scale of 0 to 10 for CS compared with DF (7.8591.14 vs. 5.779 1.83; P 0.002; effect size 1.82, large).
Results Jump test
Discussion
Table I shows the results of the jump test using the force platform with each of the models of sport shoe. None of the variables analyzed with the force platform showed significant differences between either type of sport shoe (P0.05), with the exception of velocity at PP where a higher value was attained with CS. A tendency was observed for a greater force mean (P 0.091) to be obtained at the peak of power with DF. There were no differences in Hf and h, nor were there statistically significant differences in the impact absorption phase (F2 and T2). Effect size was low for all variables.
Dorsiflexion produces a modification in muscle activation (Bourgit et al., 2008; Frank et al., 2000), but this does not mean that this difference translates into an improvement in performance. These results contrast with previous studies which found improvements in jump capacity using sport shoes which increased dorsiflexion (Faiss et al., 2010; Larkins & Snabb, 1999). In both studies, they used larger degrees of dorsiflexion (48 and 3.58, respectively) than that employed in the present study (28) so that this may be the reason why there is a discrepancy in the results. In the study by Faiss et al.
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Table II. Modified t-test performance (ms) with DF and CS
Pt 1 acceleration Pt 2 change of direction (forward to left) Pt 3 sideways movement (braking) Pt 4 sideways movement (start) Pt 5 lateral movement Pt 6 change of direction (left to backwards) Pt 7 backwards movement Total time
CS (ms)
DF (ms)
Effect size
P
553958.1 11919130 3439112 5379136 11349118 19599216.1 5199115 62379540
551958.9 12159135 3459116.3 5839144 1150990.7 20159239 517989.2 63779508
0.03 0.18 0.02 0.34 0.14 0.26 0.02 0.26
0.774 0.074 0.932 0.104 0.368 0.055 0.929 0.008
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Pt partial time. Statistical significant differences (PB0.05) are in bold.
(2010), improvements of 4 cm were found in CMJ and higher values of velocity in the take-off with the sport shoes with dorsiflexion, but in our case, no significant differences were evident. Even velocity at PP was higher with the CS, although this did not translate into greater jump capacity. Another possible explanation for these discrepancies could be the adaptation to the shoes. In the study by Faiss et al. (2010), the subjects went through a period of acclimatization to the shoes, using them for 1 hour a day for 10 days, while in the present study, this was the first time that the participants had worn this model. It is probable that the special position adopted by the foot can negatively affect subjects who are not accustomed to using this type of shoe. However, in other studies, in which DF were used in training compared with conventional sport shoes, for a period of 412 weeks, jump capacity did not improve (Cody, 1992; Cook et al., 1993; Nicopoulou et al., 1998; Pethan, 1995; Porcari et al., 1996; Tsitskaris et al., 2001). In fact in other studies, there was a greater improvement in jump capacity with conventional shoes (Ramsey, 1993). According to biomechanical studies of the muscle, a pre-stretch of the ankle flexor or extensor musculature should increase the capacity of the muscle to generate strength. It has been seen that maximum voluntary torque in the plantar flexor muscles was also developed at 108 of plantar flexion and that it decreased sharply as ankle dorsiflexion increased to more than 58 (Marsh, Sale, McComas, & Quinlan, 1981). Equally in the triceps surae, the biarticular muscle pre-stretched with dorsiflexion, and it has been shown that with the knee bent, the optimum length for torque development corresponded to almost full dorsiflexion of the ankle. Similar results were obtained with the knee extended (Sale, Quinlan, Marsh, McComas, & Belanger, 1982). This improvement was only evident at the level of the extensor musculature of the ankle, not affecting the ankle position in knee extensor peak torque in either ankle position, dorsiflexion or plantar flexion (Croce, Miller, & St Pierre, 2000).
With regard to the agility test, the sport shoes which increased dorsiflexion showed a significantly poorer performance overall. If we look at the partial times in detail, we can see a tendency towards worse results with DF in the partial times, which included a change of direction (P 0.074 and P 0.055), appearing to indicate that dorsiflexion hinders movements, which imply a quick change of direction, perhaps based on the fact that stretching the muscle caused an increase in both the contraction and halfrelaxation times (Sale et al., 1982). The results obtained in both tests cast doubt on the benefits of moderate dorsiflexion for improving performance in modalities which require jumping capacity or covering short distances, as in the case of volleyball. Furthermore, in the comfort test, there was a notable difference in favour of the CS, an aspect to be taken into account as a drawback of the DF. It would be interesting to extend this study to different degrees of dorsal and plantar flexion to get a more in-depth perspective of their influence on sport performance. Conclusions Several commercial brands have developed shoes that increase ankle dorsiflexion in an attempt to increase the extension of the plantar flexor muscles thereby improving muscle contraction and jump performance. However, we have found that our active participants had a similar jump performance with CS and with DF and that their agility decreased slightly with the use of DF. We recommend using CS during sport activities that involve repeated jumps and actions demanding agility. References Abian, J., Alegre, L. M., Lara, A. J., Rubio, J. A., & Aguado, X. (2008). Landing differences between men and women in a maximal vertical jump aptitude test. Journal of Sports Medicine and Physical Fitness, 48(3), 305310. PMID: 18974715. Baudouin, A., Spampinato, J., Amos, M., & Morag, E. (2006). The relationship between forefoot flexibility and in-shoe measurements. In International Society of Biomechanics in Sports, Proceedings of XXIV International Symposium on Biomechanics
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Influence of ankle dorsiflexion on jumping capacity
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