Sprint performance changes in adolescent athletes following a 6-week elastic resistance training program: a preliminary field study

Abstract

Background

Elastic Resistance Training (ERT) is a widely used modality in rehabilitation, but its efficacy for enhancing sprint performance in adolescents is under-researched.

Methods

Twenty-eight competitive adolescent track and field athletes (mean age: 16.64 ± 1.37 years) participated in a 6-week progressive ERT program added to their standard technical training.

Results

Significant improvements were observed across all distances. The 30 m sprint time decreased from 4.36 s to 4.29 s (p < 0.001, Cohen’s d = 0.24, small effect). The 60 m time improved from 8.16 s to 8.08 s (p < 0.001, d = 0.11, trivial effect). The most meaningful change occurred in the 400 m sprint, decreasing from 70.98 s to 68.30 s (p < 0.001, d = 0.29, small-to-moderate effect).

Conclusion

While absolute improvements in short acceleration (30 m) were small, the intervention showed greater practical relevance for speed endurance (400 m). Coaches should consider ERT as a supplementary tool for developing anaerobic capacity in youth athletes.

Introduction

The unique properties of ERT, specifically its accommodating resistance, increase tension as the range of motion is completed. While traditional inertial loads provide maximum resistance at the beginning of a movement (where the mechanical advantage is often lowest), elastic bands provide peak resistance at the end of the range of motion (terminal stance phase). This matches the human strength curve in extension movements (squats and jumps) and may enhance the ability to apply force at full hip extension—a critical component of maximum velocity sprinting. Furthermore, the elastic energy recoil requires athletes to control the eccentric (deceleration) phase actively, potentially improving neuromuscular control and stiffness. The primary advantages of ERT include the development of fundamental biomotor abilities such as strength, speed, and power [1]. Resistance training is a fundamental method used to safely and effectively develop physical performance foundations in adolescents [2]. While traditional resistance training often relies on constant external load (free weights), elastic resistance offers unique advantages by providing accommodating resistance. This dynamic tension increases towards the end of the range of motion, potentially demanding higher muscle activation during the peak contraction phase of movement [3]. Despite its popularity, research specifically examining the transfer of these strength gains to sprint speed in adolescent populations remains limited.

Furthermore, exercises such as resisted running directly overload sprint-specific musculature and movement patterns, potentially improving stride power and frequency. Sport is a dynamic field that demands the highest level of physical performance from individuals. Sustaining this performance requires athletes to establish a delicate balance among training, competition stress, and recovery processes [4]. Athletic success depends not only on genetic predisposition but also on appropriate training methodologies aimed at developing all components of physical fitness, including strength, speed, endurance, anaerobic power, flexibility, and agility [5]. In this context, the intensity, duration, and frequency of training programs must be meticulously calibrated to minimize injury risk and guide the athlete toward peak performance [6]. Resistance training is a cornerstone of athletic development, essential for enhancing muscular power and speed. Within this domain, Elastic Resistance Training (ERT) offers a distinct mechanical stimulus compared to traditional free weights. Unlike constant resistance, elastic bands provide variable load (accommodating resistance) that increases linearly with elongation. This property potentially allows for greater loading in the terminal range of motion during extension movements (squats, jumps), matching the ascending strength curve of the lower limb extensor muscles. However, the specific transfer of these mechanical benefits to track-based sprint performance in adolescents remains unclear. Furthermore, the practicality, low cost, and applicability of this training method in various settings make it an attractive option for both professional and amateur athletes.

Resistance training is a fundamental method used to safely and effectively develop the foundations of physical performance in individuals of all ages, including children and adolescents [2]. It plays a critical role in enhancing key motor abilities such as strength, speed, endurance, agility, and flexibility in young and elite athletes. These gains not only maximize athletic performance but are also utilized as a supportive measure in the treatment and rehabilitation of sports injuries [7].

Resistance exercises can be performed using a variety of materials, such as functional training equipment, free weights, and elastic bands [3]. Each material yields different effects depending on parameters like training intensity, set and repetition counts, and rest intervals. For instance, some research indicates that higher-intensity, low-repetition training programs are more effective for improving the physical performance metrics of elite athletes [8].

Elastic resistance bands offer unique advantages, particularly in increasing muscle activation levels and providing resistance throughout every phase of a movement [2]. Compared to exercises with free weights, elastic bands generate a dynamic and accommodating tension across the entire range of motion [9]. This suggests that elastic bands can be an effective training tool in sports that require significant shoulder strength and stability. Research has demonstrated that training with elastic bands can increase throwing velocity and force in sports requiring throwing performance, such as tennis and handball [10, 11].

Elastic resistance bands (e.g., Thera-Band) are an ideal tool for athletes and physiotherapists due to their lightweight, portable, and space-efficient design. These bands, available in different colors, offer graded levels of resistance, with a scale ranging from tan to gold, allowing individuals to select exercises appropriate for their strength levels [2]. This feature makes the bands suitable for both injury rehabilitation [12] and elite-level training.

The importance of elastic bands in rehabilitation is underscored by their ability to facilitate movement independent of gravity and provide greater control over the phases of motion [13]. Consequently, they serve as an effective alternative to traditional training for improving balance and postural stability following lower-extremity injuries [14]. Despite the extensive use of ERT in rehabilitation, there is a paucity of research examining its efficacy for performance enhancement in healthy adolescent populations. Specifically, while the effects of ERT on static strength are well-documented, its transfer to dynamic sprint performance—particularly speed endurance (e.g., 400 m) versus acceleration (e.g., 30 m)—remains under-explored in youth athletes. Furthermore, most existing studies utilize complex laboratory setups; there is a need for practical, field-based protocols that coaches can implement with minimal equipment. Given the practical challenges of implementing controlled trials in competitive team settings, the primary purpose of this study was to observe and quantify the changes in 30 m, 60 m, and 400 m sprint performance in adolescent athletes following a 6-week progressive ERT program. This preliminary field study aims to assess the feasibility and potential magnitude of performance changes to inform future randomized controlled trials. Based on the existing literature, we hypothesized that the 6-week ERT program would significantly improve sprint performance, with potentially greater relative gains in speed-endurance (400 m) due to the metabolic demands of the time-under-tension protocol.

Methodology

Ethical approval for the study was obtained from the Izmir Democracy University Non-Interventional Clinical Research Ethics Committee (No: 2022/02–08). All research activities were conducted in full accordance with the ethical principles for human research as outlined in the WMA Declaration of Helsinki. Written informed consent to participate was obtained from all participants. For participants under the age of 18, written informed consent was also obtained from their parents or legal guardians prior to the commencement of the study.

The study group was composed of a total of 28 athletes, with a mean age of 16.64 years, a mean height of 172.18 cm, and a mean body weight of 61.10 kg, and competitive adolescent track and field athletes (sprinters and long jumpers) actively engaged in the competitive season. Long jumpers were included in the sprinter cohort as their training regimens and plyometric profiles are highly comparable to pure sprinters during the general preparation phase. Participants had a mean training age of 3 ± 1 years. Throughout the 6-week intervention, athletes continued their standard technical track training (3 sessions/week), which included low-volume block starts and technical drills. The ERT protocol was added as a specific strength module at the beginning of these sessions.

Participants and sample size

The study employed a convenience sampling method, recruiting the entire available roster of a local youth athletic team (n = 28). A post-hoc power analysis indicated that for a Paired Samples t-Test with a medium effect size (d = 0.5) and an alpha level of 0.05, a sample size of 28 provides a statistical power (1 - β) of approximately 0.82, which is considered adequate for this pilot intervention.

Controls and standardization

To minimize confounding variables, participants were instructed to maintain their standard sleep habits and dietary intake throughout the study. However, specific hydration status, sleep quality, and biological maturity (e.g., Peak Height Velocity) were not instrumentally monitored, which is noted as a limitation of the field-based design.

Protocol considerations

The study utilized a fixed time-under-tension approach (increasing from 15 to 25 s) rather than individualized relative loading (e.g., % of 1RM). While this ensured logistical consistency in a team setting, it may not have provided an optimal overload stimulus for the stronger athletes or may have induced excessive fatigue in others. We recommend that future interventions incorporate individualized fatigue monitoring, such as Session Rate of Perceived Exertion (sRPE), to adjust daily training volumes and mitigate the risk of overtraining.

The training program was administered for 6 weeks, 3 days per week, and consisted of 3 sets. The duration commenced at 15 s and was progressively increased by 5 s every two weeks [15]. To account for physiological baseline strength differences and ensure proper exercise technique, resistance levels were stratified by sex. Female athletes utilized yellow bands (approx. 1.3 kg at 100% elongation) and male athletes utilized red bands (approx. 1.8 kg at 100% elongation). This differentiation aimed to equalize the Relative Perceived Exertion (RPE) during the high-repetition protocols (15–25 s), preventing technical breakdown that might occur if heavier resistance was applied to athletes with lower absolute upper-body strength [1, 2]. Furthermore, lighter resistance was deliberately selected to prioritize movement velocity and proper sprint mechanics over maximal force production, ensuring that the athletes could maintain high-speed technical execution without kinematic degradation.

Elongation percentage of elastic bands

To quantify the resistance used, we empirically measured the tension of the Thera-Band elastic bands (Yellow and Red) at 25% increments of elongation. Our measurements indicated that at 100% elongation (the estimated peak stretch during exercises), the Yellow bands provided approximately 1.17 kg of force, and the Red bands provided 1.60 kg. These values differed slightly from the manufacturer’s reference values (Mean Difference ≈ 15%), underscoring the importance of verifying resistance in field studies.

We stratified band selection by sex (Yellow for females, Red for males) to approximate similar relative intensity levels. However, we acknowledge that tension in elastic bands is directly proportional to elongation. Therefore, participants with longer limb lengths (greater height) experienced slightly higher absolute resistance at full extension than shorter participants. This anthropometric variation is an inherent limitation of using fixed-length elastic bands in a heterogeneous group.

Exercises with resistance bands are intended to work the body in various ways. One such exercise is the Squat, for which the resistance band is placed under the feet and held behind the nape of the neck. In this position, a squat is performed until the hips are lowered to a 90-degree angle. Another exercise is the in-place run (skip). During this movement, the elastic band is anchored to a fixed point, passed around the abdomen, and an in-place running motion is performed while maintaining tension on the band. Simultaneously, an arm and leg pull is performed with the resistance band. The band is anchored, with one end attached to the right ankle and the other end passed under the left arm and held by the hand. While keeping the band taut, the arm and leg are pulled forward at the same time. Finally, a single-leg jump onto a box can be performed with the resistance band. In this movement, the band is anchored at abdominal height and held under tension. A jump is then performed onto a box with one leg while the other knee is driven upward. These exercises are repeated for both legs. The detailed 6-week progressive training protocol is outlined in Table 1.

Table 1.

Training programs

Phase	Weeks	Duration (Time Under Tension)	Rest Interval
Phase 1	Weeks 1–2	15 s	1 min
Phase 2	Weeks 3–4	20 s	2 min
Phase 3	Weeks 5–6	25 s	3 min

6-Week Progressive Exercise Program

Exercises performed: 1. Squat, 2. Hand & Foot Pulls (Standing), 3. Resisted Vertical Jump, 4. Resisted Skip Run

These runs were performed without resistance to facilitate the transfer of potentiated neural drive to sprinting mechanics [16]

Finishing Cool-down Phase: After completing 4 × 30 m incremental runs, jog for 2 laps to cool down

Height and body weight measurements

Participants’ body weights (kg) were measured with precision using an electronic scale (Tanita BC-418 MA). Their heights (cm) were recorded while they stood in an anatomical position without shoes.

Body Mass Index (BMI)

The Body Mass Index was calculated using the following formula [17]:

Sprint speed tests (30 m, 60 m, 400 m)

Sprint tests were conducted on a tartan track using a precision timing gate system (Brower Timing System, Salt Lake City, UT, USA). Each athlete performed two trials for every distance, and the best result was recorded for analysis [18]. The principle of full recovery was applied between trials [19].

Data analysis

The collected data were analyzed using IBM SPSS Statistics 26 software.

Descriptive statistics

Categorical variables (e.g., gender, age, BMI groups) were expressed as frequency (n) and percentage (%). Numerical variables (e.g., age, height, weight, BMI) were presented as mean (x̄) and standard deviation (SD).

Statistical analyses

Data were analyzed using IBM SPSS Statistics 26. Normality of distribution was assessed using the Shapiro-Wilk test in conjunction with visual inspection of Q-Q plots. Levene’s test was used to assess homogeneity of variance. Effect sizes (Cohen’s d) were calculated for all significant pairwise comparisons to determine the practical magnitude of the differences, interpreted as: 0.2 (small), 0.5 (medium), and 0.8 (large).

Results

A total of 28 adolescent track and field athletes participated in the study. The cohort consisted of 15 males (53.6%) and 13 females (46.4%), with a mean age of 16.64 ± 1.37 years. The participants were active competitive athletes (sprinters and long jumpers) with a mean training experience of 3 ± 1 years. Anthropometric data indicated a mean height of 172.18 ± 9.46 cm, body weight of 61.10 ± 10.01 kg, and Body Mass Index (BMI) of 20.50 ± 1.99 kg/m². The detailed descriptive characteristics are summarized in Table 2.

Table 2.

Distribution of statistical findings regarding the descriptive characteristics of the participants in the study

Descriptive Characteristics		Number	%
Gender	Female	13	46.4
	Male	15	53.6
Age (years)	Under 18	17	60.7
	18 and over	11	39.3
BMI (kg/m²)	Underweight or slightly overweight	5	14.3
	Normal	23	85.7
Age (years)	Mean ± SD (Min.-Max.)	16.64 ± 1.37 (14–19)
Height (cm)	Mean ± SD (Min.-Max.)	172.18 ± 9.46 (156–187)
Weight (kg)	Mean ± SD (Min.-Max.)	61.10 ± 10.01 (44.50–82.80)
BMI (kg/m²)	Mean ± SD (Min.-Max.)	20.50 ± 1.99 (17.38–25.38)

Mean Average, SD Standard Deviation, Min. Minimum, Max. Maximum

Regarding the age distribution of the participants, 60.7% were under 18 years old, while 39.3% were 18 years or older. In terms of weight classification, 4 participants were categorized as underweight, 1 as overweight, and 23 were within the normal weight range. The mean age of the participants was 16.64 years, mean height was 172.18 cm, mean body weight was 61.10 kg, and the mean BMI was 20.50 kg/m².

In this study, the effect of elastic resistance band usage on sprint performance was statistically examined across different distances (Table 3). The 30-meter sprint time significantly decreased from a pre-test mean of 4.36 ± 0.30 s to a post-test mean of 4.29 ± 0.28 s (t(27) = 3.742, p < 0.001, Cohen’s d = 0.24). Similarly, the 60-meter sprint time improved from 8.16 ± 0.70 s to 8.08 ± 0.70 s (t(27) = 5.878, p < 0.001, Cohen’s d = 0.11). The most substantial effect was observed at the longest distance; the 400-meter sprint time decreased from 70.98 ± 9.36 s to 68.30 ± 9.26 s (t(27) = 5.774, p < 0.001, Cohen’s d = 0.29). The analyses reveal that the running times for all distances decreased to a statistically significant degree (p < 0.01). According to our findings, the 30-meter running time was determined to have decreased from a mean of 4.36 s in the pre-test to 4.29 s in the post-test. Likewise, the 60-meter running time was 8.16 s in the pre-test and improved to 8.08 s in the post-test. The most notable change occurred in the 400-meter distance, where the mean running time decreased from 70.98 s in the pre-test to 68.30 s in the post-test. These results indicate that resistance band training positively impacts the sprint performance of athletes across all tested distances and significantly shortens their running times. The pre- and post-intervention sprint times, stratified by gender, are presented in.

Table 3.

Running speeds of study participants over various distances before and after using an elastic resistance band

Pre-Post Test	N	Mean Time(s)	SD	t	p
Pre-Test-30 m run	28	4.36	0.30	3.742	0.001**
Post-Test-30 m run	28	4.29	0.28
Pre-Test-60 m run	28	8.16	0.70	5.878	0.001**
Post-Test-60 m run	28	08.08	0.70
Pre-Test-400 m run	28	70.98	9.36	5.774	0.001**
Post-Test-400 m run	28	68.30	9.26

*p < 0.05, **p < 0.01, t: Paired Sample T-Test

The pre- and post-intervention sprint times, stratified by gender, are presented in Table 4. According to Table 4, the running times for both female and male participants after the elastic resistance band intervention were significantly shorter than their pre-intervention times.

Table 4.

Comprehensive analysis of pre- and post-training sprint performance by subgroup

Subgroup	N	30 m Pre (s)	30 m Post (s)	60 m Pre (s)	60 m Post (s)	400 m Pre (s)	400 m Post (s)
Overall	28	4.36 ± 0.30	4.29 ± 0.28**	8.16 ± 0.70	8.08 ± 0.70**	70.98 ± 9.36	68.30 ± 9.26**
Female	13	4.57 ± 0.22	4.50 ± 0.22*	8.72 ± 0.53	8.63 ± 0.55**	78.13 ± 6.58	74.99 ± 7.10**
Male	15	4.17 ± 0.23	4.10 ± 0.16*	7.68 ± 0.38	7.58 ± 0.35**	64.77 ± 6.57	62.50 ± 6.67**

Values are Mean ± SD. * p < 0.05, ** p < 0.01

In the 30-meter sprint, the mean time for females decreased from 4.57 s to 4.50 s (t = 3.136, p = 0.009), while the mean time for males decreased from 4.17 s to 4.10 s (t = 2.409, p = 0.030). For the 60-meter sprint, the mean time for females improved from 8.72 s to 8.63 s, a highly significant change (t = 3.889, p = 0.002), and the mean time for males was found to have decreased from 7.68 s to 7.58 s (t = 4.281, p = 0.001). In the 400-meter run, the mean time for females decreased from 78.13 s to 74.99 s (t = 3.326, p = 0.006), while the mean time for males decreased from 64.77 s to 62.50 s, creating a very highly significant difference (t = 7.73, p < 0.001).

Subgroup analysis

A Two-Way Mixed ANOVA (Time × Gender) revealed a significant main effect for Time (F(1, 26) = 13.34, p = 0.001), confirming that sprint performance improved significantly regardless of gender. There was no significant Interaction effect (Time × Gender, p > 0.05), indicating that males and females improved at similar rates.

Descriptive statistics by group

• Females (n = 13): 30 m time improved from 4.57 ± 0.22 s to 4.50 ± 0.22 s.

• Males (n = 15): 30 m time improved from 4.17 ± 0.23 s to 4.10 ± 0.16 s.

Similar descriptive trends were observed for age subgroups, where the Over-18 group (n = 11) showed greater absolute speed but similar relative improvements to the Under-18 group (n = 17).

Regarding the changes in running speeds, the use of elastic bands did not produce a significant difference in the 30-meter performance of athletes under 18 years of age (p > 0.05), whereas it resulted in a significant improvement in the 18-and-over group (p < 0.05). In contrast, for the 60-meter and 400-meter running speeds, statistically significant improvements were observed in both age groups following the elastic resistance band intervention (p < 0.05). Across all running distances, the Time*Age interaction effect was found to have no significant impact on the change in running speeds. The overall results indicate that the use of resistance bands positively influenced the running speeds of all age groups, particularly at longer distances (60 m and 400 m).

When the changes in running speeds according to BMI groups were examined, it was observed that the use of elastic bands did not produce a significant difference in the 30-meter performance of the Underweight BMI group (p > 0.05). In contrast, a statistically significant improvement in running speeds was found in the Normal BMI group (p < 0.01). For the 60-meter and 400-meter runs, however, the situation was different, as the use of elastic resistance bands led to statistically significant improvements in the running speeds of both the Underweight and Normal BMI groups (p < 0.05 and p < 0.01, respectively).

While participants in the Normal BMI group demonstrated significant progress across all running distances, the Underweight BMI group recorded significant improvements only at the 60-meter and 400-meter distances. The analyses determined that the Time*BMI interaction did not have a significant effect on the change in running speeds (p > 0.05). These results indicate that while resistance band training was generally effective for improving running speeds, the level of improvement did not significantly differ between the BMI groups.

Discussion

This preliminary field study aimed to observe changes in sprint performance (30 m, 60 m, and 400 m) in adolescent track and field athletes following a 6-week progressive Elastic Resistance Training (ERT) program. The primary finding was that significant improvements were observed across all tested distances following the intervention, with the most distinct relative changes occurring in the 400 m sprint.

Sprint performance improvements

The analysis revealed statistically significant reductions in sprint times for the 30 m, 60 m, and 400 m distances. While the absolute improvement in the 30 m sprint (0.07 s) and 60 m sprint (0.08 s) was small, these changes occurred within a relatively short 6-week period. Previous literature suggests that resistance training can support athletic performance by providing variable load stimuli [20]. In this study, the use of ERT may have offered a supplementary training stimulus to the athletes’ standard technical regimen. Although we did not measure ground reaction forces or electromyographic (EMG) activity, theoretical models suggest that accommodating resistance might encourage force application through the full range of motion [21]. However, without direct physiological monitoring, we cannot attribute these gains to specific neural or morphological adaptations [16, 22].

Speed endurance and training volume

A notable observation was the improvement in the 400 m sprint time (mean reduction of ~ 2.68 s). The specific ERT protocol employed in this study utilized time-under-tension sets ranging from 15 to 25 s. This duration targets metabolic pathways distinct from purely explosive, short-duration activities. It is plausible that the high-repetition nature of the protocol imposed a metabolic demand that transferred favorably to speed-endurance performance. This aligns with suggestions that resistance training can enhance fatigue resistance during high-intensity exercise [23]. Nevertheless, in the absence of a control group, it is difficult to determine the extent to which these improvements were driven by the ERT intervention versus the athletes’ concurrent track training.

Subgroup observations

Gender-based analyses indicated that both male and female participants showed improved sprint times post-intervention. While male participants exhibited faster absolute times—consistent with established physiological differences in muscle mass and power output [24]—the similar rate of improvement suggests that the ERT protocol was feasible for both groups. Similarly, improvements were observed across age groups (under 18 vs. over 18) and BMI categories [25]. The finding that athletes with a normal BMI showed more consistent statistical significance in short sprints compared to underweight athletes may relate to baseline strength-to-weight ratios, though the small sample size of the underweight group (n = 5) limits this interpretation.

Limitations and future directions

The results of this study must be interpreted with caution due to several limitations inherent to its exploratory field-based design. First and foremost, the lack of a control group and randomization precludes causal conclusions; factors such as the “learning effect” (familiarity with timing gates), natural biological maturation, and concurrent technical training likely contributed to the observed results. Second, biological maturity (e.g., peak height velocity) was not assessed, preventing differentiation between training effects and natural growth. Third, resistance bands were assigned based on sex rather than individual strength levels (e.g., % 1RM), which may have resulted in suboptimal loading for some athletes. Finally, no physiological (e.g., lactate, EMG) or biomechanical (e.g., force plate) variables were measured to verify the underlying mechanisms of performance change.

Conclusion

This preliminary study demonstrates that a 6-week progressive ERT program implemented within a standard track and field curriculum was associated with improved sprint performance in adolescent athletes. The protocol appeared particularly relevant for speed endurance (400 m). However, these findings are descriptive in nature. Future research utilizing randomized controlled trials, biological maturity assessments, and objective load monitoring is required to validate the effectiveness of ERT and elucidate the physiological mechanisms responsible for performance enhancement in youth populations.

Authors’ contributions

Neşe Akpınar Kocakulak: Conceptualization, Methodology, Supervision, Research Administration, Writing – Original Draft, Writing – Review & Editing. Hasan Esenkaya: Data Curation, Formal Analysis, Investigation, Visualization. All authors have read and agreed to the published version of the manuscript.

Funding

No funding was received for this study.

Data availability

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

Ethical approval for the study was obtained from the Izmir Democracy University Non-Interventional Clinical Research Ethics Committee (Decision No: 2022/02–08). All research activities were conducted in full accordance with the ethical principles for human research as outlined in the WMA Declaration of Helsinki. Written informed consent to participate was obtained from all participants. For participants under the age of 18, written informed consent was also obtained from their parents or legal guardians prior to the commencement of the study.

Consent for publication

Written informed consent to publish the data collected was obtained from all participants and, where applicable, their legal guardians.

Competing interests

The authors declare no competing interests.