Beata Makaruk
Department of Sports for All, Józef Piłsudski University of Physical Education in Warsaw, Faculty of Physical Education and Health in Biala Podlaska, Poland

Keywords: sprint training method, hurdles, stride length, stride frequency.  

Introduction. Straight-line sprint running is an essential factor to many sports, including athletics, football, or rugby. Based on the kinematics model, effectiveness of sprint running is determined by stride length and stride frequency [1]. An increase in one parameter without decrease the second one results in an improvement in the running velocity. However, an increase in stride length often leads to a decrease in stride frequency and conversely, an increase in stride frequency reduces the length of stride. Because only the optimal values of stride length and frequency make sprinting at the fast speed possible, researchers try to find training methods that can be used to manipulate these kinematics. One of the most common ways used to lengthen running stride is resisted sprinting (e.g. 

pulling a sled, tire, running uphill or with resisted bands) [2]. In turn, research showed that assisted sprinting (e.g. towing using a harness or stretch elastic tubing) is an effective method to induced changes in stride frequency [3].

     There is, however, little information on the third popular method to improve sprint performance through the use of sticks, marks or mini-hurdles to regulate stride kinematics. Using this method, coaches may directly influence the length and frequency of running stride. The key factor is the distance of the markers. Research by Makaruk et al. [4] demonstrated that sprint training with a lengthened distance between sticks resulted in an improvement in running velocity by an increase in stride length. On the other hand, when the distance between sticks was shortened, increasing running velocity was accompanied by an increase in stride frequency. 

Objective of the study. Because the height of the training obstacle also could be a way of manipulating stride kinematics, the purpose of this study was to identify the differences in stride kinematics between sprints with increasing the height of the hurdles in sprinters and jumpers.

Research methods and organization. Twelve male athletes (mean ± SD, age: 21.5 ± 1.9 years, height 178.4 ± 5.1 cm, body mass 74.6 ± 6.4 kg) volunteered to participate in this study. All subjects were informed about the nature of this study. Six of the 12 athletes are sprinters, 4 long jumpers and 2 high jumpers. All the procedures were approved by the Ethics Commission for Scientific Research of the University of Physical Education in Warsaw.

     The testing session consisted of general warm-up (5-minute jog, 8-minute dynamic stretching) and 2 x 20 m knee lifts and heel kicks, 1 x 40 m submaximal-intensity sprint. After the warm-up, each participant performed three 20-m flying sprints [5] in a random order in the following conditions: with flat, medium and high mini-hurdles (0.5, 13 and 20 cm high, respectively). The obstacles were set from 20 to 40 m and with a 220 cm distance between mini-hurdles. The participants were asked to perform the sprint at maximum speed. The Optojump Next (Microgate, Italy) was used to assess stride kinematics. This device consists of two pairs of measurement bars (1-m length transmitters and receivers) placed parallel to each other on the sprint track and connected to a computer via a USB port. The system detected all interruptions in communication between the bars with a timing accuracy of 1 ms. Contact time was measured as the time from footstrike to toe-off of the same foot, flight time was measured as the time from foot toe-off to footstrike of the opposite foot, stride length was determined as the distance from the tip of the spike-shoe at toe-off to the tip of the opposite leg’s spike-shoe at toe-off, while mean step velocity was determined as the ratio between stride length and the sum of the contact time of the pushing leg and flight time during this stride.

     Descriptive statistics are presented as means ± SD. The Shapiro-Wilk test was used to confirm whether the variables were normally distributed. A one-way analysis of variance (ANOVA) with repeated measures was used to determine if any significant differences existed between three sprint conditions. When significant effects were observed, Tukey post-hoc tests were applied. Statistical significance was set at p < 0.05. Statistica v. 13.0 software was used for all statistical calculations.

Results. Mean ± SD values of kinematic parameters are demonstrated in Table 1. The analysis revealed that running velocity and stride frequency were significantly greater (p < 0.05) in the flat mini-hurdles condition compared to the high mini-hurdles condition. Stride length significantly increased (p < 0.05) in the high mini-hurdles condition when compared with the flat mini-hurdles conditions. There were no significant differences (p > 0.05) between the conditions for contact time and flight time. There were also no significant differences (p > 0.05) between the medium condition and the other conditions for all parameters.       

Table 1. Acute effects of sprint running training on sprint kinematics (mean±  SD) through mini-hurdles with different height*

#Significantly different (p<0.05) from run over flat mini-hurdles.

Discussion. Sprint running over sticks or low obstacles is a method often used by coaches and athletes attempting to improve stride kinematics. However, there is little in the way of scientific evidence to support this practice. Therefore, the purpose of this study was to examine how manipulation of the height of mini-hurdles influence kinematics of sprinting. The main findings of the study showed that an increased height of obstacles during sprint may lead to a change kinematic parameters. We found that running velocity and stride frequency decreased when the height of mini-hurdles increased from flat mini-hurdles to high mini-hurdles, but stride length increased. Additionally, our research revealed that using the medium mini-hurdles, did not change significantly running velocity, stride length and frequency, when compared to the flat mini-hurdles condition. 

     The previous studies only reported the effects of distance between markers on stride kinematics [4,6]. According to our knowledge, this is the first research that compares the effects of mini-hurdles with different heights on the stride kinematics in athletics athletes. The results of this study showed that running speed significantly reduced with a 19.5 cm increase of mini-hurdles (from 0.5 to 20 cm, but did not significantly change when an increase was 12.5 cm (from 0.5 to 13 cm). In examining the possible mechanism for these observations, it is logical to suggest that decreasing running speed were produced by a decrease in stride frequency resulted from an increase in stride length [4]. We assume that an increase in stride length was due to athletes raised the knees higher to overcome the higher obstacles. Thus, for coaches wishing to increase stride length, it appears that relatively high obstacles may be effective to achieve this training goal. However, it is necessary to monitor changes in the other kinematic parameters before the implementation of the higher mini-hurdles. Although contact time and flight time showed little change between all of the conditions, longer stride may demonstrate the potentially negative effect. For example, the longer horizontal distance from the centre of mass to the foot at touchdown as the result of elongated stride may implicate an increase in the braking forces and increased hamstring injury [7]. 

     We found that using the medium height of mini-hurdles did not significantly change the stride kinematics relative to flat condition, however, there was a trend towards an increase in stride length and decrease stride frequency. It can therefore be concluded that this condition did not significantly alter the athletes’ running technique and may be recommended for athletes during training periods when movement pattern should not be dramatically changed [8]. Further research is needed to examine the longer-term effects of running over mini-hurdles and other sprint training methods on sprint kinematics [9].

    Practical applications. Using mini-hurdles in running sprints may change some of athlete’s stride kinematics according to training needs. It needs to be highlighted that the implementation of high mini-hurdles requires carefully monitored training loads, especially during the competitive season. The current research has shown that high mini-hurdles (20 cm) may lead to unstable locomotor patterns and thus adversely affect running velocity by decreasing stride frequency and increasing stride length. Therefore, the coaches should use training obstacles for skill acquisition such as starting with sprints over flat markers or sticks, then implement a gradual increase of obstacles height.

References

1. Mero A., Komi P. V., Gregor, R. J. Biomechanics of sprint running. Sports Medicine, 1992, vol. 6, no. 13, pp. 376-392.
2. Petrakos G., Morin, J. B., Egan B. Resisted sled sprint training to improve sprint performance: a systematic review. Sports Medicine, 2016, vol. 3, no. 46, pp. 381-400.
3. Makaruk B., Stempel P., Makaruk H. The effects of assisted sprint training on sprint running performance in women. Acta Kinesiologica, 2019, vol. 2, no. 13, pp. 5-10.
4. Makaruk B., Makaruk H., Sacewicz T. The efficacy of speed training conducted by applying runs between guide strips. Physical Education and Sport, 2009, vol. 3, no. 53, pp. 167-172.
5. Makaruk B., Makaruk H., Sacewicz T., Makaruk T., Kędra S., Długołęcka, B. Validity and reliability of measurement of kinematic parameters in a running speed test. Polish Journal of Sport and Tourism, 2009, vol. 2, no. 16, pp. 85-92.
6. Saito S., Takahashi K. Immediate effect of running over flat makers to improve stride frequency. ISBS Proceedings Archive, 36th Conference of the International Society of Biomechanics is Sport, Auckland, New Zealand, September, 10-14, 2018.
7. Tabor P., Mastalerz A., Iwańska D., Grabowska O. Asymmetry indices in female runners as predictors of running velocity. Polish Journal of Sport and Tourism, 2019, vol. 3, no. 26, pp. 3-8.
8. Young W. B., McDowell M. H., Scarlett B. J. Specificity of sprint and agility training methods. Journal of Strength and Conditioning Research, 2001, vol. 3, no. 15, pp. 315-319.
9. Alcaraz P. E., Carlos-Vivas J., Oponjuru B. O., Martinez-Rodriguez, A. The effectiveness of resisted sled training (RST) for sprint performance: a systematic review and meta-analysis. Sports Medicine, 2018, vol. 9, no. 48, pp. 2143-2165.

Corresponding author: fizkult@teoriya.ru

Abstract

The purpose of this study was to examine the influence of the height of mini-hurdles on the kinematics of sprinting in sprinters and jumpers. Twelve male athletes (mean ± SD, age: 21.5 ± 1.9 years, height 178.4 ± 5.1 cm, body mass 74.6 ± 6.4 kg) ran maximal flying sprint under 3 different conditions: with flat, medium and high mini-hurdles (0.5, 13 and 20 cm high, respectively). The obstacles were set from 20 to 40 m. The Optojump Next (Microgate, Italy) was used to assess running velocity, stride length, stride frequency, contact time and flying time. The analysis revealed that running velocity and stride frequency were significantly greater (p < 0.05) in the flat mini-hurdles condition compared to the high mini-hurdles condition. Stride length significantly increased (p < 0.05) in the high mini-hurdles condition when compared with the flat mini-hurdles conditions. There were no significant differences (p > 0.05) between the medium condition and the other conditions for all sprint kinematics. We suggest that coaches and practitioners should adjust the height of sprinting obstacle depending on training needs.