Dynamic balance ability during single-leg drop landing across different age groups of junior gymnasts

Abstract

[Purpose] Dynamic balance and shock absorption during landing are essential for gymnastics performance and injury prevention; however, age-specific landing biomechanics remain unclear. This study examined age-related differences in dynamic postural control and shock absorption during single-leg drop landing (SDL) among junior gymnasts. [Participants and Methods] Forty junior gymnasts (elementary school: n=12; junior high school: n=12; high school: n=16) performed SDL from a 20-cm platform onto a force plate. Peak vertical ground reaction force (Fz), buffering coefficient, and center of pressure (COP) trajectory length during early (20–200 ms) and prolonged (20 ms–5 s) post-landing phases were analyzed. Group comparisons were conducted using one-way analysis of variance or Kruskal–Wallis tests with post hoc analyses. [Results] Significant group differences were observed in all parameters. High school gymnasts showed lower Fz, shorter COP trajectories, and higher buffering coefficients than elementary and junior high school groups. No significant differences were found between elementary and junior high school gymnasts, suggesting a transitional developmental phase with neuromuscular inefficiency. [Conclusion] Dynamic postural control and shock attenuation improve with age in junior gymnasts, particularly after peak height velocity (PHV). Age-specific neuromuscular training may help reduce ankle injury risk and enhance performance.

INTRODUCTION

Gymnastics is a highly technical sport that demands precise motor control, particularly during landing tasks, where the lower limbs must absorb forces several times the body weight within fractions of a second^{1, 2)}. Among these biomechanical challenges, maintaining dynamic postural control during landings is crucial for performance and injury prevention. Specifically, the act of “sticking” a landing without excessive sway or stepping is usually used as a performance benchmark and an implicit indicator of neuromuscular control^{3, 4)}.

Lower extremity injuries, particularly those around the ankle joint, are common among gymnasts of all ages^5,6,7). Previous studies have shown that poor neuromuscular control, proprioceptive deficits, and decreased dorsiflexion range can contribute to altered landing mechanics and increased injury risk^{8, 9)}. While adult and collegiate gymnasts have been extensively studied in this context, less is known about how these biomechanical capabilities develop during adolescence, particularly during critical growth periods.

Recent studies suggest that athletes usually demonstrate transient declines in balance, force attenuation, and coordination during the period of peak height velocity (PHV)—a phase marked by rapid skeletal growth and temporary neuromuscular imbalance^{10, 11)}. These developmental changes may create a mismatch between skeletal structure and motor control, placing the athlete at greater risk of mechanical overload or injury during demanding movements such as single-leg landings¹²⁾.

Despite the importance of these transitions, only a few studies have used quantitative biomechanical methods to evaluate dynamic balance and impact absorption across different age groups in youth gymnasts. Most existing research has been either cross-sectional with adult athletes or focused on general balance assessments, rather than task-specific postural demands during gymnastics landings^{13, 14)}. Moreover, even when landing mechanics are examined, developmental aspects, such as motor learning from accumulated training experience, are usually not differentiated from chronological age.

Therefore, a clear gap exists in understanding how neuromuscular control during landing evolves with biological development and sport-specific experience in youth gymnasts. Recognizing these changes can help tailor injury prevention and training strategies to different developmental stages.

This study aimed to investigate age-related differences in dynamic postural control and shock absorption during single-leg drop landing (SDL) in junior gymnasts. We hypothesized that older gymnasts (i.e., high school group) would demonstrate lower peak vertical ground reaction force (Fz), superior buffering coefficient values, and shorter center of pressure (COP) trajectories than younger gymnasts due to greater neuromuscular maturation and accumulated experience.

By evaluating these variables across distinct developmental groups, we aim to provide age- and growth-sensitive biomechanical indicators for ankle injury risk and support the design of stage-specific neuromuscular training programs.

PARTICIPANTS AND METHODS

Forty junior gymnasts (18 males, 22 females; age range: 8–17 years) from Wakayama Prefecture voluntarily participated in this study.

They were stratified into three groups based on school level as follows: elementary (n=12; 8–11 years), junior high (n=12; 12–14 years), and high (n=16; 15–17 years) school groups.

Participant characteristics by age group and sex are summarized in Table 1.

Table 1. Participant characteristics (mean ± SD).

Variable	Elementary (n=12)		Junior high (n=12)		High school (n=16)
Sex (n)	Male (6)	Female (6)	Male (6)	Female (6)	Male (6)	Female (10)
Height (cm)	146.4 ± 6.6	142.5 ± 5.5	156.2 ± 4.1	149.5 ± 4.9	166.0 ± 3.9	154.8 ± 4.9
Weight (kg)	36.0 ± 6.7	33.9 ± 4.6	47.5 ± 4.2	41.5 ± 4.5	59.0 ± 3.9	47.8 ± 4.9
BMI (kg/m2)	16.7 ± 2.1	16.6 ± 1.2	19.5 ± 1.0	18.6 ± 2.5	21.4 ± 0.4	19.9 ± 0.8

Values are presented as mean ± standard deviation. BMI: body mass index.

All athletes trained at least three times per week and had a minimum of two years of continuous gymnastics experience. Written informed consent was obtained from all participants and their legal guardians. This study was approved by the SUMIYA Ethics Committee (Approval No. 018032012) and conducted in accordance with the Declaration of Helsinki.

The task consisted of a single-leg drop landing (SDL) from a 20-cm platform onto the force plate, which was positioned 30 cm from the anterior edge of the platform to the marked landing point on the force plate, followed by maintaining a single-leg stance for 8 s. Participants were verbally instructed to “land as softly and stably as possible, keep your arms crossed over your chest, and maintain the single-leg stance for 8 seconds”. Ground reaction forces and center of pressure data were collected at a sampling frequency of 1,000 Hz using a force plate system. The latter five trials of ten trials were analyzed¹⁵⁾. Peak vertical ground reaction force, buffering coefficient, and COP trajectory lengths during the early (20–200 ms) and prolonged (20 ms–5 s) post-landing phases were calculated. Data were normalized to body weight and foot length. A schematic illustration of the SDL task is shown in Fig. 1.

Fig. 1.

Single-leg drop landing.

a: The participant stands on a 20-cm-high platform placed behind the force plate, balancing on one leg. b: The participant jumps forward onto the marked landing point on the force plate located 30 cm from the anterior edge of the platform. c: After landing, the participant maintains a single-leg stance for 8 seconds.

Statistical analyses were performed using EZR version 1.68 (Saitama Medical Center, Jichi Medical University, Saitama, Japan), which is a graphical user interface for R (The R Foundation for Statistical Computing, Vienna, Austria). The mean of five valid trials was used for analysis, and statistical significance was set at p<0.05.

RESULTS

Significant group differences were observed in all biomechanical parameters. High school gymnasts demonstrated lower peak vertical ground reaction force values, shorter COP trajectory lengths, and superior buffering coefficients compared with elementary and junior high school gymnasts (Table 2). Differences between elementary and junior high school groups were limited. After adjustment for years of gymnastics experience, group differences remained evident, indicating that maturation effects were not solely attributable to training duration.

Table 2. Biomechanical parameters during single-leg drop landing (mean ± SD).

	Elementary school (n=12)	Junior high school (n=12)	High school (n=16)
Fz (% body weight)	634.97 ± 86.16	546.50 ± 58.99	374.31 ± 53.45***
Buffering coefficient (N/ms)	15.75 ± 3.29	12.12 ± 1.69	6.39 ± 1.90***
COP trajectory (20–200 ms, % foot length)	92.91 ± 4.91	88.44 ± 5.71	64.34 ± 14.01***
COP trajectory (20 ms–5 s, % foot length)	315.68 ± 39.47	271.60 ± 36.60	215.98 ± 30.49***

Values are mean ± SD. ***p<0.001 vs. elementary and junior high school groups. COP: center of pressure.

DISCUSSION

This study examined developmental differences in dynamic postural control and impact attenuation during SDL in junior gymnasts, revealing that high school gymnasts consistently demonstrated superior biomechanical efficiency compared to their younger peers. These advantages were evident across all metrics—lower peak Fz, reduced COP trajectories, and improved buffering coefficients. Importantly, these effects remained significant even after adjusting for years of gymnastics experience, suggesting that maturation contributes uniquely to movement quality beyond the effects of accumulated training.

The marked reduction in Fz value and buffering coefficient in older athletes indicates improved shock attenuation capabilities, which likely reflects neuromuscular maturation and cumulative skill refinement. While earlier studies^{12, 13)} emphasized improvements in strength and coordination post-puberty, recent research has expanded on this by examining movement efficiency in youth sports. For example, Farana et al.¹⁶⁾ and Teng et al.¹⁷⁾ highlight that refined landing strategies emerge not only from physical growth but also from long-term exposure to sport-specific demands. Therefore, it is plausible that the interaction between biological development and training history jointly shapes the observed movement outcomes.

Similarly, the observed reduction in COP trajectory length among older gymnasts aligns with studies indicating that sensory-motor integration and anticipatory postural adjustments improve with age and experience¹⁸⁾. Our data suggest that high school gymnasts exhibit enhanced feedforward control and proprioceptive responsiveness, enabling more rapid stabilization within the early post-landing window (20–200 ms)—a critical phase for injury prevention.

However, attributing these findings solely to biological age without accounting for motor learning would be reductive. While age-based groupings provide a proxy for neuromuscular development, athletes with longer training histories tend to exhibit superior biomechanical coordination independent of age¹⁰⁾. Our ANCOVA results, which retained group differences after adjusting for years of gymnastics experience, support the notion that age and experience have additive, but not redundant, effects on landing mechanics.

This dual influence of age and skill acquisition must be emphasized when interpreting transitional periods such as PHV. Athletes undergo rapid somatic growth during PHV, which can disrupt neuromuscular timing and joint stability^{11, 19)}. Our findings of increased COP displacement and impact force among elementary and junior high school gymnasts possibly reflect this temporary mismatch between structure and control. Nonetheless, the concurrent impact of training exposure during this period may buffer some of the risks associated with biological immaturity¹²⁾.

From an injury prevention standpoint, these findings highlight a critical opportunity: implementing neuromuscular training before or during PHV may mitigate coordination deficits and reduce mechanical loading on vulnerable structures such as the growth plate. Interventions such as balance board training, eccentric loading, and proprioceptive drills have demonstrated efficacy in similar youth populations²⁰⁾. Moreover, SDL assessments may serve as a field-based screening tool to identify gymnasts at high injury risk due to poor postural recovery or elevated impact forces.

This study has some limitations that should be acknowledged. First, although training experience was statistically controlled, we did not account for qualitative factors such as training content, intensity, or coaching style—all of which may influence neuromuscular skill development. Second, the absence of direct maturity indicators (e.g., Tanner stage or predicted age at PHV) limits our ability to precisely map developmental transitions. Third, while our analysis focused on vertical kinetics and COP trajectories, future research should incorporate three-dimensional kinematics and muscle activation data to capture a more comprehensive profile of landing control strategies.

Despite these limitations, our study provides updated, evidence-based insight into the developmental biomechanics of gymnasts. It reinforces the need to individualize injury prevention and performance programming based on growth stage and training age, rather than relying solely on chronological classification.

In summary, the present study demonstrated that dynamic balance ability and shock absorption capacity during SDL progressively improve with age among junior gymnasts. High school gymnasts exhibited superior postural control, lower peak vertical ground reaction force, and more efficient force buffering compared with elementary and junior high school gymnasts. These findings suggest the presence of a transitional neuromuscular phase during the PHV period, characterized by temporary reductions in coordination and increased mechanical loading on the lower extremities.

From a clinical and practical perspective, these developmental differences highlight the importance of implementing age- and maturation-specific neuromuscular training strategies. Early-stage interventions focusing on balance control, proprioceptive training, and landing technique refinement may help mitigate the transient decline in postural stability observed during growth spurts and reduce the risk of ankle joint injuries. Monitoring growth-related changes and tailoring training loads according to developmental stage, rather than chronological age alone, may further optimize long-term athletic development in young gymnasts.

Third, although ground reaction forces were normalized to body weight and COP trajectory was normalized to foot length, the variables were not normalized to body height. Because height increases substantially during adolescence and may influence mechanical leverage and landing dynamics, some of the observed group differences may have been partially affected by anthropometric growth rather than neuromuscular maturation alone. Future studies should consider height-normalized or allometric scaling approaches to better isolate developmental effects.

Conflict of interest

The authors declare no conflicts of interest.