Abstract
s provide an ideal setting for enhancing adolescents’ health and fitness. Short-term intensive interventions are particularly relevant, but the effectiveness of plyo- metric exercises in jointly improving aerobic and anaerobic performance remains uncertain. This study aimed to evaluate the effects of plyometric-based training, in the form of interval workouts during physical education lessons, on power and endurance in adolescents. A total of 87 boys and 95 girls (aged 14–15 years) participated in an 8-week intervention, performing plyometric exercises twice weekly during physical education classes. The analyzed parameters were jump height (JH) measured by countermovement jump (CMJ) and distance covered during multistage fitness test (MFT). The results showed significant improvements among boys participating in the JH experiment and the distance covered in the MFT (p< 0.05); thus, the effect sizes were relatively small (ES < 0.3). Also, the prevalence of positive responders was more common for boys than girls; however, the difference was statistically insignificant (p= 0.09). These findings suggest that plyometric training has the potential for improving physical fitness, even in the context of developing opposing physical abilities, particularly in boys. However, the effects varied across individuals and were generally small, highlighting the need to optimize the intervention to achieve more pronounced results tailored to individual characteristics. Keywords:secondary school; physical fitness; youth; health;
insignificant (p= 0.09). These findings suggest that plyometric training has the potential for improving physical fitness, even in the context of developing opposing physical abilities, particularly in boys. However, the effects varied across individuals and were generally small, highlighting the need to optimize the intervention to achieve more pronounced results tailored to individual characteristics. Keywords:secondary school; physical fitness; youth; health; school-based setting; plyometric exercises; power; endurance; aerobic; anaerobic 1. Introduction In the context of adolescent health, body composition and cardiovascular and metabolic parameters are often emphasized, with many studies focusing on these as- pects [1–3]. This focus is appropriate, since obesity and hypertension in childhood and adolescence significantly increase prematurely in adulthood [4]. However, it should not be forgotten that health also encompasses physical fitness [5,6], and adolescence is a critical period for developing physical fitness, which can have long-term benefits in adulthood [7]. Physical education (PE) lessons provide a natural setting for implementing various forms of physical activity to enhance physical performance [8]. In recent years, numerous authors have demonstrated that various physical activity programs introduced into physical education programs have favorable effects on health and performance [9,10]. Standard PE programs require the inclusion of substantial physical activity, but the short duration of lessons (typically 45 min) may not be sufficient to promote specific adaptations. Therefore, Sports2025,13, 15 https://doi.org/10.3390/sports13010015
Sports2025,13, 15 2 of 12 there is a need to implement short time interventions that address this issue without negatively impacting the PE curriculum [11,12]. Various exercise protocols have been explored in PE classes, yet no consensus exists on the optimal approach. The adaptability of these programs offers wide-ranging pos- sibilities [13,14]. Achieving wide-ranging effects on physical fitness concurrently is also desirable. Even the development of opposite anaerobic and aerobic abilities is possible; thus, this concept is explored mainly in adults and athletes [15]. There is a gap in the field considering the joint development of power and endurance in adolescents. The topic is relevant, as (previously mentioned) the time of physical education lessons is limited and requires maximal effectiveness. In this context, implementing plyometric activities in the form of high-intensity interval training (HIIT) can be particularly relevant. It was shown that using the interval method is time-saving and effective in training focused on developing both anaerobic and aerobic abilities [15]. However, there is a lack of studies that explore this issue among adolescents. Some promising results were provided by Racil et al. [16], where HIIT with plyometric exercises was effective among young females with obesity in improving their metabolic status, but effects on physical fitness have not been checked to date. Plyometric exercises are based on the stretch-shortening cycle [17]. When training youth and untrained individuals, it is recommended to perform low-intensity exercises with a higher number of repetitions. This approach helps to develop movement proficiency and build tissue capacity for handling higher loads. Such exercises serve as an excellent introduction for individuals unfamiliar with plyometric training for adolescents [18]. In the context of this study, this approach allows for a greater number of repetitions in a shorter period, resulting in more work performed and a greater stimulation of the cardio- vascular system. Thus, concurrent improvements in both anaerobic and aerobic fitness can be expected [15,19]. A plyometric-focused approach aims to perform rapid repetitions to increase total work performed [20]. These explosive movements engage fast-twitch muscle fibers, potentially enhancing muscle power and anaerobic performance due to higher work- loads
resulting in more work performed and a greater stimulation of the cardio- vascular system. Thus, concurrent improvements in both anaerobic and aerobic fitness can be expected [15,19]. A plyometric-focused approach aims to perform rapid repetitions to increase total work performed [20]. These explosive movements engage fast-twitch muscle fibers, potentially enhancing muscle power and anaerobic performance due to higher work- loads in less time. Plyometric training—characterized by quick transitions between muscle lengthening and shortening—has been shown to improve motor functions, strength, and endurance in youth [21]. When combined with HIIT, it effectively engages both the ner- vous and muscular systems, leading to gains in strength, power, and endurance [16,22,23]. Therefore, plyometric HIIT, involving more movements and greater muscle engagement, enhances training effects and meets the criteria for a brief intervention fitted into the physi- cal education lesson. Many studies conducted on various youth populations demonstrate improvements in jump performance following plyometric training. However, there is a lack of research within the physical education context, along with a limited consideration of its effects on aerobic capacity [24]. A study by Andrade et al. [25] showed positive concurrent effects on both anaerobic and aerobic abilities after plyometric-based interventions in adult participants. Regarding this, the implementation of this approach in adolescents during physical education lessons seems to be relevant. Moreover, plyometric exercises have shown potential not only for enhancing physical fitness but also for addressing health challenges such as obesity in children [16,26–28]. Previous studies have demonstrated its effectiveness in improving body composition, metabolic health, and overall physical well-being in youth populations [16,26–28]. This underscores the broader applicability of plyometric HIIT beyond athletic performance. The aim of this study is to examine the concurrent effects of interval plyometric-based training conducted during physical education lessons on the development of power and endurance in adolescents. Specifically, this research seeks to evaluate how incorporating plyometric exercises within a structured school curriculum impacts physical performance
Sports2025,13, 15 3 of 12 metrics related to jump height and sustained endurance in school-aged individuals. Addi- tionally, this study aims to quantify the prevalence of adolescents who experience significant improvements in measured physical performance parameters. We hypothesize that a sig- nificant proportion of adolescents will demonstrate improvements in power and endurance following an intervention program incorporated into physical education lessons. The findings from this study can inform physical education curriculum designers, coaches, and educators about the effectiveness of integrating plyometric-based training within school settings to enhance adolescents’ physical fitness. By demonstrating improvements in both power and endurance, this approach could become a valuable addition to PE programs, helping students develop critical athletic skills and overall physical capacity. Moreover, this study provides a structured framework for implementing plyometric exercises safely and effectively in classroom environments, promoting long-term health benefits and supporting students’ physical fitness. 2. Materials and Methods 2.1. Participants Participation was voluntary, and students could withdraw at any time. Both stu- dents and their parents or legal guardians were informed about this study’s objectives and procedures. Written informed consent was obtained from school principals, par- ents, and participants prior to the commencement of this study. Sample size estimation was conducted using G*Power software version 3.1 [29]. Based on the adopted study design—four studygroups (boys and girls, each divided into experimental and control groups) and two repeated measurements (baseline and post-intervention)—with an ef- fect size of 0.35, an alpha level of 0.05, and a power of 0.8 [30], the minimum required sample size was determined to be 28 participants. Participants were recruited from one secondary school. Initially, eight classes were enrolled in this project. Group assignments were made using simple cluster (class) randomization without replacement via an online tool (www.randomization.com, accessed on 16 January 2024). To minimize disruption to lesson schedules and the school’s daily operations, randomization was conducted based on the division of students into classes. Initially, 241 students from all classes were identified. Before group allocation, several students were excluded for the following reasons: refusal to participate (n = 16), medical contraindications (n = 4), and engagement in
accessed on 16 January 2024). To minimize disruption to lesson schedules and the school’s daily operations, randomization was conducted based on the division of students into classes. Initially, 241 students from all classes were identified. Before group allocation, several students were excluded for the following reasons: refusal to participate (n = 16), medical contraindications (n = 4), and engagement in additional sports activities within the past six months (n = 12). During the intervention, additional participants were excluded (n = 27) for missing more than 20% of physical education classes. No adverse effects from the intervention were reported. The final sample comprised 179 adolescent students. 2.2. Procedures Assessments were conducted at two time points: before the 8-week intervention (baseline) and immediately after the intervention. All measurements were performed on a single day between 8:00 a.m. and 1:00 p.m. in sports halls under standardized conditions for all groups. First, body morphology measurements were taken. Next, participants completed a warm-up, followed by the jump test and the beep test. During performance tests, participants wore T-shirts, shorts, and shoes; however, anthropometric measurements were conducted barefoot. The study design is illustrated in Figure.
Sports2025,13, 15 4 of 12Sports 2025, 13, x FOR PEER REVIEW 4 of 12 Figure 1. The study design. 2.3. Anthropometric Measurements Body height was measured to the nearest 0.1 cm using an anthropometer (GPM An- thropological Instruments, DKSH Ltd., Zürich, Switzerland) in a standing position and barefoot, in accordance with the guidelines of the International Society for the Advance- ment of Kinanthropometry (ISAK) [31]. Body weight was assessed using a Tanita In- nerScan V, model BC-601 (Tanita Co., Tokyo, Japan). Prior to the measurements, partici- pants were instructed to empty their bladders, avoid excessive fluid intake, and maintain their usual breakfast routines. During the assessment, participants stood barefoot and shirtless on the scale, with heels placed on the rear electrodes, legs straight at the knees and hips, arms slightly abducted and flexed at the shoulders, elbows straight, and fingers in contact with the manual electrodes. Body mass index (BMI) was calculated as weight in kilograms divided by height in meters squared (kg/m 2 ). 2.4. Multistage Fitness Test To evaluate maximal heart rate and estimate aerobic capacity, the multistage fitness test (MFT) was administered. For the target audience of this study, the test/retest reliabil- ity coefficients were found to be 0.89 for children (139 boys and girls aged 6 to 16) [32,33]. The MFT requires continuous running between two lines set 20 m apart, timed to a series of recorded beeps. Participants begin running at a speed of 8.5 km/h and must turn 180° at each line. The running speed increases by 0.5 km/h every minute, as indicated by audio signals. The test continues until the participant is unable to maintain the required pace. The total distance covered, measured in meters, is analyzed. 2.5. Countermovement Jump Test The countermovement jump (CMJ) test was conducted following the protocol de- scribed by Comfort et al. [34], using a Chronojump contact mat (Chronojump Bosco-sys- tem, Barcelona, Spain), whose reliability has been well-established [35]. Participants stood upright with equal weight distribution on both feet, keeping their hands placed on their hips throughout the test. They performed a rapid downward movement by bending their
jump (CMJ) test was conducted following the protocol de- scribed by Comfort et al. [34], using a Chronojump contact mat (Chronojump Bosco-sys- tem, Barcelona, Spain), whose reliability has been well-established [35]. Participants stood upright with equal weight distribution on both feet, keeping their hands placed on their hips throughout the test. They performed a rapid downward movement by bending their knees to approximately 90 degrees, immediately followed by a maximal vertical jump. Participants were instructed to execute the countermovement as quickly as possible and to maintain a consistent technique across all trials. Adopting their preferred depth of Figure 1.The study design. 2.3. Anthropometric Measurements Body height was measured to the nearest 0.1 cm using an anthropometer (GPM Anthropological Instruments, DKSH Ltd., Zürich, Switzerland) in a standing position and barefoot, in accordance with the guidelines of the International Society for the Advancement of Kinanthropometry (ISAK) [31]. Body weight was assessed using a Tanita InnerScan V, model BC-601 (Tanita Co., Tokyo, Japan). Prior to the measurements, participants were instructed to empty their bladders, avoid excessive fluid intake, and maintain their usual breakfast routines. During the assessment, participants stood barefoot and shirtless on the scale, with heels placed on the rear electrodes, legs straight at the knees and hips, arms slightly abducted and flexed at the shoulders, elbows straight, and fingers in contact with the manual electrodes. Body mass index (BMI) was calculated as weight in kilograms divided by height in meters squared (kg/m 2 ). 2.4. Multistage Fitness Test To evaluate maximal heart rate and estimate aerobic capacity, the multistage fitness test (MFT) was administered. For the target audience of this study, the test/retest reliability coefficients were found to be 0.89 for children (139 boys and girls aged 6 to 16) [32,33]. The MFT requires continuous running between two lines set 20 m apart, timed to a series of recorded beeps. Participants begin running at a speed of 8.5 km/h and must turn 180 ◦ at each line. The running speed increases by 0.5 km/h every minute, as indicated by audio signals. The test continues until the participant is unable to maintain
The MFT requires continuous running between two lines set 20 m apart, timed to a series of recorded beeps. Participants begin running at a speed of 8.5 km/h and must turn 180 ◦ at each line. The running speed increases by 0.5 km/h every minute, as indicated by audio signals. The test continues until the participant is unable to maintain the required pace. The total distance covered, measured in meters, is analyzed. 2.5. Countermovement Jump Test The countermovement jump (CMJ) test was conducted following the protocol de- scribed by Comfort et al. [34], using a Chronojump contact mat (Chronojump Bosco-system, Barcelona, Spain), whose reliability has been well-established [35]. Participants stood upright with equal weight distribution on both feet, keeping their hands placed on their hips throughout the test. They performed a rapid downward movement by bending their knees to approximately 90 degrees, immediately followed by a maximal vertical jump. Participants were instructed to execute the countermovement as quickly as possible and to maintain a consistent technique across all trials. Adopting their preferred depth of
Sports2025,13, 15 5 of 12 countermovement was encouraged, as this approach enhances consistency and reliability in performance, as noted by Petronijevic et al. [36]. Both feet were required to land simulta- neously, and participants were instructed to ensure symmetrical take-offs and controlled landings to absorb impact. Flexion of the lower limbs during the flight phase was not permitted. Five trials were performed, with adequate rest intervals between them, and the best result was considered for analysis. 2.6. Intervention A plyometric-based interval training program, following the Tabata method (20 s of work, 10 s of rest), was implemented over eight weeks, as it has previously been shown to be an effective approach for physical education lessons [37]. The intervention was conducted twice per week during physical education classes. Students had a total of three hours of physical education weekly, distributed across two days. On one of these days, students had two consecutive hours, which allowed for this specific scheduling. The eight-week duration was selected to ensure continuity of the intervention while avoiding interruptions caused by national holidays, religious observances, or school activities that could lead to missed classes. The training volume increased progressively throughout the intervention. During the first two weeks, students completed four rounds of exercises per session. This increased to six rounds in weeks three and four and to eight rounds in the final four weeks. The target workout intensity was set at 7–8 on the rating of perceived exertion (RPE) scale [11], and participants were familiarized with the RPE scale before the intervention began. Each session started with a standardized 10 min warm-up. The intervention included the following plyometric exercises: ankle hops, burpees, high knees, shoulder taps with hand claps, butt kicks, two-leg mountain climbers, squat jumps, and alternating-leg mountain climbers. Students were instructed to perform as many repetitions as possible during each 20 s work interval. Each 20 s round focused on a single exercise, which was alternated systematically to maintain engagement and prevent stagnation. Exercises were alternated between upper and lower body movements to reduce fatigue in specific muscle groups, allowing for greater overall training intensity
alternating-leg mountain climbers. Students were instructed to perform as many repetitions as possible during each 20 s work interval. Each 20 s round focused on a single exercise, which was alternated systematically to maintain engagement and prevent stagnation. Exercises were alternated between upper and lower body movements to reduce fatigue in specific muscle groups, allowing for greater overall training intensity and ensuring variety to sustain participant motivation. This full body approach also aimed to enhance cardiovascular and respiratory system activation by engaging a larger number of muscles. For the remainder of the physical education classes, students in the intervention group followed the standard first-year curriculum, focusing on skill development across various sports. The control group continued with the same standard physical education program throughout the intervention period. This program comprised activities aligned with the first-year curriculum, including team sports such as basketball, soccer, and volleyball, and individual activities like running and gymnastics. The focus was on skill acquisition, teamwork, and general fitness development, with no additional emphasis on plyometric training or structured interval programs. 2.7. Statistics The data were presented as means, standard deviations, and 95% confidence inter- vals. Change values (∆) were calculated by subtracting pre-intervention results from post-intervention results. To assess data characteristics, Shapiro–Wilk’s test was used to check normality, Levene’s test to evaluate homoscedasticity, and Mauchly’s test to assess sphericity. A three-way repeated measures ANOVA (sex×intervention×time) was utilized. Partial eta-square (pη 2) values were calculated and interpreted as small (0.01), moderate (0.13), or large (0.26). When statistically significant differences were obtained, Tukey’s post hoc tests for varying sample sizes were conducted. Cohen’s effect sizes
Sports2025,13, 15 6 of 12 (ESs) were calculated and classified as small (≤0.2), moderate (≤0.5), or large (>0.5) to evaluate detailed differences [38,39]. Responders (Rs) and non-responders (NRs) were identified based on whether they showed significant improvement after the intervention. For classification based on changes in CMJ and MFT results (∆), the typical error (TE) ap- proach was applied, consistent with recent studies [40]. The following equation was used: TE = SDdiff/ √ 2, where TE represents the typical error, and SDdiff denotes the standard de- viation of the difference between post- and pre-intervention values. The chi-square (χ 2) test was applied to assess whether sex differentiated the prevalence of positive effects. An alpha level ofp< 0.05 was established for statistical significance across all tests. All calculations were performed using Statistica 13.0 software (StatSoft Poland, Krakow, Poland). 3. Results Table by groups. Table 1.Study participants’ descriptive statistics. Variable Boys in the Experimental Group n = 52 Boys in the Control Group n = 35 Girls in the Experimental Group n = 51 Girls in the Control Group n = 44 Mean±SD (95%CI) Mean ±SD (95%CI) Mean ±SD (95%CI) Mean ±SD (95%CI) Calendar age [years] 14.54±0.54 (14.39–14.69) 14.57±0.78 (14.3–14.84) 14.55±0.58 (14.39–14.71) 14.52±0.59 (14.34–14.7) Body height [m] 1.76±0.07 (1.74–1.78) 1.78±0.07 (1.75–1.8) 1.65±0.06 (1.63–1.67) 1.65±0.06 (1.63–1.67) Body mass [kg] 63.25±9.59 (60.58–65.92) 66.8±13.74 (62.08–71.52) 57.16±10.18 (54.29–60.02) 55.98±8.11 (53.51–58.44) Body mass index [kg/m 2 ] 20.32±2.65 (19.58–21.06) 21.02±3.08 (19.96–22.08) 20.92±3.41 (19.97–21.88) 20.67±2.99 (19.76–21.58) Pre-CMJ height [cm] 34.00±5.06 (32.59–35.41) 32.93±4.42 (31.41–34.45) 24.13±3.75 (23.08–25.19) 22.34±3.76 (21.2–23.49) Post-CMJ height [cm] 34.91±5.13 (33.48–36.34) 33.09±4.53 (31.54–34.65) 24.58±3.82 (23.5–25.65) 22.18±3.76 (21.03–23.32) ∆-CMJ height [cm] 0.91±1.4 (0.52–1.31) 0.17±1.13 (−0.22–0.55) 0.45±1.11 (0.13–0.76) −0.16±1.01 (−0.47–0.14) Pre-multistage fitness test [m] 1479.23±403.4 (1366.92–1591.54) 1389.71±420.29 (1245.34–1534.09) 772.16±240.5 (704.51–839.8) 826.82±249.8 (750.87–902.76) Post-multistage fitness test [m] 1581.15±403.35 (1468.86–1693.45) 1449.14±475.72 (1285.73–1612.56) 838.82±243.42 (770.36–907.29) 848.64±294.87 (758.99–938.28) ∆-multistage fitness test [m] 101.92±189.95 (49.04–154.81) 59.43±169.74 (1.12–117.74) 66.67±158.48 (22.09–111.24) 21.82±107.04 (−10.72–54.36) Abbreviation: Pre—measures before the intervention; Post—measures after the intervention;∆—difference between post- and pre-measures. Three-way (sex×time×intervention) repeated measures ANOVA revealed that the factors of sex, intervention, and time independently and significantly affected jump height outcomes (allp< 0.01). Additionally, interactions between sex×time and intervention×time were
Description
The study evaluates plyometric training's impact on adolescents' physical fitness.