Introduction

Vaulting, a key event in artistic gymnastics, encompasses a series of interconnected phases: run-up, hurdle or round-off, take-off, pre-flight, repulsion, post-flight and landing1. The execution of these phases plays a crucial role in vaulting competition victory2. Especially, both the run-up phase and take-off phase are directly related to required velocity and height for performing difficult vaulting movements3,4. The primary objective of the run-up is to acquire the necessary horizontal velocity for successful performance, emphasizing the need to maintain consistently high velocity on the springboard, which is determined by the interval velocity during the limited 25 m run-up distance2. The penultimate step, antepenultimate step, and last step in limited 25 m run-up distance bridge the gap between the run-up phase and take-off phase, facilitating the conversion of horizontal velocity into vertical velocity5. The velocity and angle of the hurdle step (landing on the springboard before take-off) can establish favourable conditions for height achieved on the vaulting table and flight distance6. The ratio of step length in the last three steps reflects an athlete’s mastery of their own run-up velocity and run-up rhythm. The successful execution of the take-off phase ensures a proper direction of motion, preparing for the jumping technique in the pre-flight phase. Jumping ground reaction force plays a vital role in the take-off phase, determining the pre-flight height and providing the body’s centre of gravity with sufficient initial velocity to rise forward and upward during the pre-flight phase. And the greater the jumping ground reaction force, the increased the instantaneous vertical velocity gained7. However, insufficient jumping ground reaction force applied to the springboard may result in inadequate energy conversion required for support on vault8,9.

Previous studies have shown that both kinetic and kinematic variables are essential for assessing physical performance in gymnastics10. Kinetic variables, such as jumping ground reaction force and impulse, provide insights into the forces exerted by gymnasts during movements. Kinematic variables, such as velocity, acceleration, and joint angles, help in understanding the motion characteristics of gymnasts11. In the context of gymnastics, these variables are crucial for evaluating performance and identifying areas for improvement. This study specifically examines the correlation between run-up velocity and jumping ground reaction force to understand their combined effect on vault performance.

In recent years, there has been a decline in the performance of Chinese female gymnasts on vault, culminating in no qualifications for the vault final at the 2021 Tokyo Olympics. The existing literature has indicated that insufficient run-up velocity and jumping ground reaction force are the primary variables hindering Chinese female gymnasts from executing challenging vaulting maneuvers12,13. However, the correlation between run-up velocity and jumping ground reaction force remains uncertain, and there is also a lack of clarity regarding the distinct requirements of different vault types for run-up velocity and jumping ground reaction force. The study hypothesized that there are significant differences in run-up velocity and jumping ground reaction force across vaulting types, and that these differences will affect athletes’ performance of more difficult vaulting maneuvers.

To test this hypothesis, the study aims to investigate the run-up velocity and jumping ground reaction force of elite female gymnasts in China, compare these variables across different vault types and movements, and explore the correlations between these variables. Investigations and analyses, such as those conducted in this study are important for providing tailored references for coaches and gymnasts to improve and optimize the training of run-up velocity and jumping ground reaction force and to develop challenging maneuvers for Chinese female elite gymnasts on vault.

Methods

Testing subjects

The study analyzed 16 female elite gymnasts who all earned Master Sportsman certifications (the highest technical certification among Chinese athletes). The participants’ related parameters were shown in Table 1. Performance testing was an annual regular part of the preparation for national gymnasts in China. The study was conducted in accordance with the Declaration of Helsinki. Before the tests, all participants and their legal guardians were informed about the research objectives and testing procedures, and also provided written informed consent for publication of these case details, which was approved by the College Research Ethics Committee of Wuhan Sports University (Application No: WHSU-07038854; Date of approval: 07 August 2021).

Table 1 The participants’ related parameters.
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Testing procedures

Between September 1, 2023, and January 10, 2024, the tests were conducted throughout 4 provinces in China, namely Guizhou, Guangxi, Zhejiang, and Yunnan. The tests were conducted in standardized gymnastics training halls, which are also training grounds for the China National Team. All apparatus installation was completed before the test. In addition to maintaining the vaulting table height according to international standards of 1.25 m, room temperature was controlled between 25 and 27 °C, and wind speed was kept below 1 m per second to ensure that the test results were primarily determined by the variables investigated.

The following items were tested: run-up velocity, step length, jumping ground reaction force, and related body angles (Table 2). Run-up velocity was measured using an infrared velocimeter (TCi-System 2018, Brower Timing Systems, America). HD action videos were captured using the Qingde Zhiti Sports Intelligent Motion Video and Data Feedback System (Tsing-i, China), enabling frame-by-frame analysis of step lengths and body angles. Jumping ground reaction force was measured using the biomechanical Portable Multi-Component Force Plate Pressure Test Bench Model 9286B (Kistler, Switzerland). The Force Plate settings were as follows: frequency set at 1000 Hz, threshold adjusted to 20 N. Peak force (N) was recorded and then compared.

A warm-up routine followed by two pre-vault tests under controlled training conditions provided athletes with an opportunity to acclimate to the testing environment and make any necessary adjustments. As shown in Fig. 1, four infrared velocimeters were strategically located approximately 3 m outside the runway sides, while a pressure test bench was mounted under the springboard. Each participants was asked to complete three times vault movements both in the Front handspring and the Tsukahara, size of data set will be 192 in total, 96 in the Front handspring group, 96 in the Tsukahara group. Vault types and movements tested are detailed in Table 3. Additionally, the 30 m sprint velocity, an important talent selection criterion for gymnasts worldwide, was measured using the TCi-System 2018 on the track14.

Table 2 The vault parameters about jumping ground reaction force.
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Fig. 1
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Measurement of run-up velocity and jumping ground reaction force.

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Table 3 The testing movements on vault.
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Statistical analysis

The data were analyzed using IBM SPSS 26.0 for Windows (SPSS Inc, Chicago, IL). Descriptive statistics, including the maximum value, mean, and standard deviation, were calculated for continuous variables to provide insights into the non-parametric tests of the experimental data. The normality of the data was assessed using the Shapiro-Wilk test. The results showed that all variables were normally distributed (p > 0.05). A paired sample t-tests were used to explore the differences in run-up velocity, jumping ground reaction force and other variables between different vault types (Front Handspring and Tsukahara). Spearman correlation coefficients (ρ) were used to express the correlations among variables. Multiple linear regression analysis was employed to examine the relationships between run-up velocity, jumping ground reaction force, and other variables in both two types of vault. Statistical significance was determined with p-values less than 0.05. In order to verify that the data on the variables were randomly distributed, we performed diagnostic tests, including checking residual plots and testing for multicollinearity. The results showed that all assumptions were met, allowing us to perform regression analysis.

Findings

Run-up velocity

From Table 4, it is evident that the run-up velocity of excellent female gymnasts reaches its peak in the last 5 m run-up distance. Through the paired sample t-tests conducted on the interval run-up velocity of vaulting movements, a significant difference (p < 0.05) was identified in before the last 10 m run-up velocity and the last 5 m run-up velocity, but no significant difference in the 25 m run-up velocity (p > 0.05) as well as in the last 10 –5 m run-up velocity between the Front handspring and the Tsukahara vault (p > 0.05).

Table 4 Run-up velocity of the Front Handspring and Tsukahara vault (m/s).
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Table 5 The step lengths of the last three steps and the hurdle step (m).
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The mean values of the step lengths of the antepenultimate step, the penultimate step, the last step, and the hurdle step were 1.93 m, 2.1 m, 2.18 m, and 1.61 m, respectively, when the athletes were completing the Front handspring; and the mean values of the antepenultimate step, the penultimate step, the last step, and the hurdle step were 2.5 m, 2.37 m, 2.37 m, and 1.71 m, respectively, when the athletes were completing the Tsukahara vaults. The hurdle step has the shortest distance when the athletes were completing the Front handspring and the Tsukahara vaults. Notably, both the Front handspring and the Tsukahara vaults show significant differences in the penultimate step (p = 0.03), last step (p = 0.01), and hurdle step (Table 5, p = 0.04).

Jumping ground reaction force

In total, jumping ground reaction force exerted in the vertical downward direction by outstanding Chinese female gymnasts reached 3933.96 ± 1025.01 N. And these was a significant differences in jumping ground reaction force between the Front handspring and Tsukahara the vault (p < 0.05). Overall, this study revealed a positive correlation between jumping ground reaction force and the difficulty of the movement on vault (p < 0.05). And the increased the difficulty of the movement, the greater the required jumping ground reaction force.

Table 6 Related body angle of front handspring vault and Tsukahara vault (°).
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Through the paired sample t-tests conducted on the different body angles of Front handspring vault and Tsukahara vault, this study found that there were significant differences in the hip joint angle and trunk-to-ground angle during pedaling and jumping (p < 0.05), but no significant difference in the knee joint angle (p > 0.05) between the Front handspring and the Tsukahara vaults. The landing angle was measured as 78.30°, while the take-off angle was 89.50°. The landing angle and take-off angle of the Front handspring and the Tsukahara vaults were not significantly different (Table 6, p > 0.05).

The relationship between run-up velocity and jumping ground reaction force

To explore the extent to which run-up velocity affects athletes’ jumping ground reaction force, Jumping ground reaction force was taken as the dependent variable, and all interval run-up velocity (a. 25 m run-up velocity, b. before the last 10 m run-up velocity, c. the last 10–5 m run-up velocity, d. the last 5 m run-up velocity) were taken as the regression independent variables. The probability of companionship was 0.0000, which was considered to be able to describe the companionship relationship with the multiple linear regression model, and the corresponding regression coefficients table was continued (Table 7). After eliminating the variables with P-value greater than 0.05 in the table of regression coefficients, and derive the regression equation Y of jumping ground reaction force and run-up velocity as:

$$y = 7205.423 + 4125.665 \ast a-2212.435 \ast b-779.76 \ast c-92.646 \ast d.$$
Table 7 Linear regression model analysis of variance.
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There was a significant correlation between jumping ground reaction force and before the last 10 m velocity (ρ = − 0.469, p < 0.01) as well as the last 5 m (ρ = − 0.604, p < 0.01), but not significantly with 25 m run-up velocity (p > 0.05) and 30 m sprint velocity (p > 0.05). Moreover, the correlation analysis showed a strong positive correlation between weight (ρ = 0.862, p < 0.01) and jumping ground reaction force, but no significant correlation was found between height (p > 0.05) and jumping ground reaction force (Table 8).

Table 8 The relationship between jumping ground reaction force and related variables.
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Discussions

Run-up velocity

One objective of this research is to examine interval run-up velocity and its influencing factors. This study found that the interval run-up velocity of Chinese excellent female gymnasts showed a trend of increasing gradually in the limited 25 m run-up distance and reached the highest velocity of 6.69 m/s. Nevertheless, related studies have shown elite vault athletes’ run-up velocity reached 7.93 m/s during the Olympic gymnastics competitions15, even reaching 8.6 m/s during the world’ s best vaulting gymnasts16. Thus, enhancing the vaulting run-up velocity is crucial for Chinese female gymnasts to perform more difficult movements on vault.

This study identified a significant difference in before the last 10 m run-up velocity and the last 5 m run-up velocity between the Front handspring and Tsukahara vaults. The Front handspring vault exhibits a higher run-up velocity before the last 10 m, while the Tsukahara vault has a higher run-up velocity within the last 5 m. When performing difficult movement of Front handspring vault, proper control of the run-up velocity during the final two steps could be beneficial for maintaining stability while executing a forward body rotation in mid-air16. However, the Tsukahara vault requires more appropriate forward turning velocity as it is already prepared for the subsequent turn when supporting the horse. It has been reported that world-class gymnasts can speed up to 9.95 ± 0.74 m/s and 8.58 ± 0.18 m/s in the last and penultimate steps of the run-up3, which provides vaulting gymnasts with horizontal velocity to execute difficult manoeuvres. So for Tsukahara vault, the last three steps of the run-up should not be decelerating but rather accelerating.

This study observed that athletes displayed a consistent rhythm in the final three steps of the run-up while executing identical vault movements, based on measured step lengths and velocities. The horizontal velocity produced by the run-up and the accuracy of the athlete’s subjective perception in the subsequent phases, as well as the completion of the movement, all are mainly dependent on whether there is a stable rhythm in the last three steps17. Furthermore, it was noted that the penultimate step had a longer stride length compared to the ultimate step. To optimize the run-up, it was suggested that reducing the width of the penultimate step allows for sufficient reaction distance for the hurdle step, aiding athletes in regulating their muscle status. This adjustment can improve the utilization of run-up velocity and create favourable conditions for a more effective take-off. Previous studies have shown that when the step length difference between the last step and the other two steps among the last three steps of a run-up is approximately 10–20 cm, utilization is improved18. This discrepancy plays a crucial role in enhancing horizontal velocity generation and optimizing the height of the centre of gravity during pedaling jumps, thereby influencing subsequent take-off on the springboard.

The 30 m sprint run is an important and popular speed training for Chinese gymnasts to develop their displacement velocity traditionally, and 30 m sprint velocity always is a significant talent selection index for gymnasts. However, this study found that there was not significant correlation between jumping ground reaction force and 30 m sprint velocity. The run-up velocity for a limited 25 m distance on the vault may differ from the sprint velocity for a 30 m distance on the track, and needs special requirement for interval run-up velocity, stride length, step frequency, and so on.

Jumping ground reaction force

Our research team reported the significant importance of jumping ground reaction force for male elite gymnasts’ performance on vault13. Furthermore, maintaining appropriate knee and hip joint angles during pedaling is also crucial for facilitating rapid push and stretch movements. However, few studies have analyzed the jumping ground reaction force of female elite gymnasts and its related influencing factors like related body angle on vault. This study observed that Chinese exceptional female gymnasts exhibited an impressive jumping ground reaction force of 3933.96 ± 1025.01 N, equivalent to 9.94 times the average standard gravity. The vaulting pedaling jump stage primarily relies on the lower limb articulations to provide support and generate propulsion3. During vaulting, contraction of knee muscles and ankle flexors supports pedaling, enhancing the reaction force necessary for the first take-off.

This study found that the hip joint angle of Chinese female gymnasts was about 141.9° at the time of pedaling. Previous studies have found that the optimal hip joint angle during pedaling ranges between 108° and 148°, while the knee joint demonstrates optimal performance at approximately 165°19. These proper joint angles may facilitate optimal pedaling efficiency17. Related study also discovered that a smaller knee angle during pedaling corresponds to lower vertical force gained20. In addition, this study also observed the hip joint angle was about 156.1° at the time of jumping which has an increase of 14.2° comparing the some angle at the time of pedaling. Increasing the hip joint angle can reduce the loss of vertical velocity, augment the forward flipping torque of the body, and increase angular momentum during movement completion4,21. When the knee angle is too small, it may impede the stretching of muscle groups at each joint and limit their ability to store elastic potential energy. A too small knee angle might also cushion some of the jumping ground reaction force, thereby reducing the generation of upward force and the overall force transferred to the vertical direction, resulting in excessive vertical velocity loss and the longer take-off times during pedaling. However, some studies have shown that appropriately reducing the angle of the knee joint can facilitate the accumulation of elastic potential energy in the lower limb muscles, thereby enabling enhanced force generation during extension and improved vertical velocity22. Therefore, maintaining an optimal knee angle is essential for maximizing force generation and minimizing energy loss during pedaling.

Previous studies have found that the optimal trunk-to-ground angle during take-off for high-difficulty vaulting movements is between 73° and 85°, which facilitates the execution of technical manoeuvres18. The research found the trunk-to-ground angle of Chinese female gymnasts was about 83.96° during pedaling and decreased to 76.9° during jumping. During the jumping phase, athletes exhibit a smaller trunk-to-ground angle compared to pedaling on the springboard, indicating a forward lean of the upper body and active arm extension in preparation for the jump. However, excessively small trunk-to-ground angles at the start of pedaling and jumping may have a negative impact on the athlete’s overall height in the air.

Maintaining an optimal landing angle of approximately 65° facilitates effective braking, minimizing velocity loss, and generating higher vertical velocity for subsequent difficult vaulting movements23. This study observed that Chinese female gymnasts’ landing angle was 78.3°, may potentially influence braking and the conversion efficiency of horizontal velocity generated during the run-up.

The relevant studies have demonstrated that there is a positive correlation between take-off angle and vertical jump height during a rapid run-up4. If the centre of body weight is excessively forward, it can lead to inadequate extension and diminished vertical velocity. A larger jump angle enhances jumping ground reaction force while reducing horizontal velocity loss during take-off. This study observed that Chinese female gymnasts exhibited a jump angle of 89.50° during take-off, which closely approached the vertical angle. This indicates the effective conversion of horizontal velocity generated during the run-up into vertical velocity24.

The relationship between run-up velocity and jumping ground reaction force

A previous study revealed that the run-up velocity and run-up rhythm of gymnasts directly influence both the magnitude and direction of their jumping ground reaction force on vault11. A decrease of 7% in horizontal jumping velocity may reduce the landing distance on the springboard by 13%, while a reduction of 7% in vertical velocity may lead to a 25% decrease in landing on the springboard distance25. However, few studies have analyzed the relationship between run-up velocity in different intervals and jumping ground reaction force on vault. This research observed a significant positive correlation between vaulting power and the last 10–5 m run-up velocity, but a negative correlation between vaulting power and before the last 10 m velocity as well as the last 5 m velocity. The results of this study showed that there maybe a non-linear relationship between the run-up velocity and jumping ground reaction force of vaulters. If the run-up velocity exceeds optimal levels, athletes may face challenges in executing a proper take-off following the hurdle step, then leading to inadequate vertical velocity and compromised body control. Related researches reported that once a gymnasts’ run-up velocity surpasses a certain threshold, their jumping ground reaction force may plateau and subsequently decline26. Therefore, finding the optimal balance in run-up velocity is crucial to ensure gymnasts have enough time and control to execute a successful take-off and achieve the desired vertical velocity for performing more difficult vaulting movements. Moreover, young gymnasts undergoing rapid physical development and improvements in technical level encounter challenges in controlling their maximum run-up velocity, such as inaccurate pedaling placement, excessive pedaling height, and excessively high horizontal velocity. And all these faults ultimately hinder training effectiveness. On the other hand, a slow run-up velocity can result in insufficient horizontal velocity and limited forward rotational power, making it difficult to execute intricate manoeuvres. Therefore, in training, gymnasts can opt for sub-maximum velocities, focusing on cultivating a proficient run-up rhythm and difficult movements that provide better control throughout the entire process. By adopting this approach combined with appropriate pace selection, gymnasts may effectively stabilize their competitive performance and unlock their full potential.

The results of the study showed that there was a significant positive correlation between pedal strength and body weight, but there was no significant effect with height. In the traditional philosophy of gymnast selection usually favors more petite athletes, but according to the data, high level female gymnasts, with their relatively heavier body weights, are more conducive to improving the rate of the run-up and the power of the stomp jump during the pedaling and assisting process, and are more helpful in fulfilling the subsequent need to vacate the air27. At the same time this challenges the traditional preference for shorter gymnasts and suggests that a more diverse body type may be more favorable for certain vaulting techniques11. It is important to enrich the selection criteria to select a variety of potential vaulting athletes. Scientifically evaluate gymnasts of different body types, including those who produce more power on the vault, have greater muscle mass, and are able to perform more difficult rotational manoeuvers.

Limitations

Our study has several limitations. On the one hand, the analyzed data were obtained from 16 female elite gymnasts and four difficult vaulting movements. However, it is of great importance to increase the number of samples to reveal the overall level of the run-up velocity and jumping ground reaction force of Chinese female elite gymnasts on vault more accurately. On the other hand, the performance on vaulting competitions maybe influenced by multiple factors, such as personal characteristics, psychology of competition, etc. Through this study performed the testing in national training and competition venues, there may still be some discrepancies in the data between these tests and the vaulting competitions. Future studies should consider a broader array of movements and a larger, more diverse group of athletes to validate and extend our findings.

Conclusion

There are specific requirements for run-up velocity and jumping ground reaction force in different vaulting types as well as in different vaulting movement. The step lengths, especially the hurdle step length and the last three steps lengths, may influence the run-up velocity. Body angles including the hip angle, trunk-to-ground angle, landing angle, and jumping angle, all may influence the magnitude of jumping ground reaction force. In future training, it is imperative that the running rhythm and jumping technique of Chinese female elite gymnasts be emphasized over the limited 25 m run-up distances. Scientific treatment of weight control is imperative for improving jumping ground reaction force.