Abstract
ecent studies have shown that lower-limb plyometric training can effectively enhance muscle strength and explosiveness, which are particularly important for improving jumping ability. The purpose of this study was to evaluate the effects of plyometric training on vertical, lateral, and horizontal jumping abilities, and their subsequent impact on basketball shooting performance and sports injury prevention. A quasi-experimental design was used, recruiting 30 male college-level basketball players from Taiwan, who were randomly assigned to an experimental group (n= 15) and a control group (n= 15). Both groups participated in 2 h of basketball training daily, while the experimental group additionally engaged in plyometric training twice a week. The results revealed significant improvements in the experimental group in several key areas, including rate of force development (RFD), ground reaction force (GRF), jump height, jump distance, and both horizontal and vertical forces, across vertical, lateral, and horizontal jumps. Specifically, vertical jumps required the highest ground reaction force, followed by lateral jumps, with horizontal (step-back) jumps requiring the least. The optimal angles for the resultant force during take-off were found to be between 66.1 ◦ and 66.8 ◦
(RFD), ground reaction force (GRF), jump height, jump distance, and both horizontal and vertical forces, across vertical, lateral, and horizontal jumps. Specifically, vertical jumps required the highest ground reaction force, followed by lateral jumps, with horizontal (step-back) jumps requiring the least. The optimal angles for the resultant force during take-off were found to be between 66.1 ◦ and 66.8 ◦ for lateral jumps, and between 56.2 ◦ and 57.2 ◦ for step-back jumps, while vertical jumps did not show significant variation in take-off angle. In terms of basketball performance, the experimental group demonstrated significantly better post-test results in all three types of jump shots, with the highest accuracy observed in the vertical jump shot, followed by the lateral jump shot, and the lowest in the step-back jump shot. Furthermore, the experimental group experienced a substantial reduction in sports injury rates, with the injury rate decreasing to 6%. These findings indicate that plyometric training not only enhances jumping performance, but also contributes to injury prevention by strengthening lower-limb muscles. This study provides a theoretical basis for coaches to develop comprehensive training programs that improve athletic performance and reduce injury risk. Keywords:vertical jump; lateral jump; horizontal jump; plyometric training; injury prevention 1. Introduction Jumping is considered an essential movement in basketball skills, because it not only enhances basketball performance, but also helps to strengthen the lower-limb muscles [1]. A successful basketball athlete fundamentally possesses vertical, lateral, and horizontal (backward) jumping abilities, which are crucial for basketball performance. Vertical jump- ing ability is utilized in rebounding, jump balls, dunking, step-forward jump shots, and leaning jump shots (also known as leaners). Lateral jumping ability is applied in drib- bling side-to-side movements and lateral jump shots. Backward jumping ability is used in step-back jump shots. Appl. Sci.2024,14, 12015.
Appl. Sci.2024,14, 12015 2 of 17 Basketball jump shots are directly related to basic jumping movements [2], which also indicates that lower-limb strength, flexibility, and coordination can help basketball athletes to quickly jump on the court [3]. Excellent leg strength allows for higher jumps, quick changes in direction, faster sprints, and better jumping and landing, enabling athletes to maintain smooth movement during dynamic actions [4]. However, for basketball athletes to develop excellent jumping ability, they must engage in lower-limb strength training, in order to activate the muscle power of the lower limbs to counteract ground reaction forces [5]. Additionally, the knees and ankles must handle lateral movements and rotations at different angles, allowing the lower limbs to maximize power output and enhance athletic performance [6]. Research shows that lower-limb injuries are the most common injuries among male and female college basketball players [7]. The most common lower- limb injuries are ankle ligament sprains and knee injuries [8]. The cause of these injuries is the stress from constant jumping, landing, and sudden changes in direction during games and practices. Research also indicates that structural knee joint injuries among basketball athletes are significantly associated with playing time, usage rate, and prolonged competition [9]. Therefore, incorporating lower-limb exercises into training programs is indispensable, as it helps to improve basketball athletes’ jumping ability and prevent sports injuries [10]. PT is a fast and explosive exercise that can effectively enhance muscle strength and power [11]. Research indicates that jumping ability can be linked to PT [12]. Many studies have shown that PT can significantly improve muscle strength, power, jumping perfor- mance, and overall athletic performance [13–17]. Additionally, evidence suggests that incorporating PT into basketball training can enhance the explosive power and vertical jump ability of players’ lower limbs [18]. Furthermore, other studies have indicated that strength training following these regimens indeed helps in reducing injury rates [19], as increased muscle strength can enhance skeletal stability and reduce the risk of injuries caused by sports activities. Thanks to training interventions, it has been possible to identify the performance of vertical and lateral jumps. However, there are
players’ lower limbs [18]. Furthermore, other studies have indicated that strength training following these regimens indeed helps in reducing injury rates [19], as increased muscle strength can enhance skeletal stability and reduce the risk of injuries caused by sports activities. Thanks to training interventions, it has been possible to identify the performance of vertical and lateral jumps. However, there are currently no studies that explain the differences between vertical, lateral, and horizontal jumps. The kinematic differences among these three types of jumps have not yet been evaluated. Further research is needed to better confirm these differences. Based on an analysis of the existing literature, the purpose of this study was to examine the impact of vertical, lateral, and horizontal jumping abilities on basketball jump shot performance, and to understand how plyometric training aids in injury prevention. The hypothesis of this study was that twelve weeks of PT could significantly enhance three types of jumping abilities, thereby improving jump shot performance and aiding in injury prevention. 2. Materials and Methods The participants of this study were recruited from a university’s college-level male basketball team in Taiwan. The recruits underwent pre-testing. All the participants were required to undergo regular basketball skills training (five times a week, for two hours each session), and were divided into two groups. The experimental group received additional PT twice a week, for 120 min per session. After the experiment, both groups underwent post-testing. A statistical analysis was conducted based on the pre- and post-test data. The research design was quasi-experimental [20]. 2.1. Participants The study population consisted of college-level male basketball athletes from 16 teams from a university in Taiwan, comprising a total of approximately 192 athletes. According to Mills and Gay, the sample size needed to be at least 10% of the population [21]. This study publicly recruited 30 participants, achieving a sample size that represented 10% of the total population. The normality of the sample distribution was examined using a quantile–quantile plot (Q–Q plot), and the 95% confidence interval (CI) was calculated [22].
be at least 10% of the population [21]. This study publicly recruited 30 participants, achieving a sample size that represented 10% of the total population. The normality of the sample distribution was examined using a quantile–quantile plot (Q–Q plot), and the 95% confidence interval (CI) was calculated [22].
Appl. Sci.2024,14, 12015 3 of 17 The results showed that the participants’ ages, heights, weights, years of athletic experience (years of participating in basketball training), and sports injury rates over the previous three months (training five days a week, for two hours per day, totaling 120 h) all followed linear normal distributions. These variables were within the 95% confidence interval (CI) ranges, indicating that the sample demonstrated normality. The 30 samples were randomly divided into an experimental group and a control group.t-tests of the pre-test mean values for the background factors did not show significant differences, indicating homogeneity between the two groups, as shown in Table. The potential risks to participants were not greater than those faced by non-participants, and were considered minimal. The participants’ rights were not affected, as participation was voluntary and non-coercive, and informed consent was obtained from the participants in advance, with signatures and dates. This study was approved by the First Human Research Ethics Review Committee of National Cheng Kung University Hospital, with approval number A-ER-113–165. Table 1.Participant homogeneity analysis. Variable EG (n= 15) M±SD CG (n= 15) M±SD 95% Confidence Interval t-Value p-Value Lower Bound Upper Bound Age (years) 22 ±1.06 22 ±1.08 −0.70 0.69 −0.021 0.984 Height (cm) 177.5 ±3.78 177.6±4.05 −2.65 2.04 −0.281 0.783 Weight (kg) 74.5 ±8.91 74.5±6.90 −6.38 6.32 −0.009 0.993 Years of athletic experience 9.25±1.15 9.28±1.28 −0.74 0.69 −0.080 0.937 Number of sports injuries (%) 22±12.06 26 ±14.73 −8.05 15.83 0.698 0.496 EG represents the experimental group, and CG represents the control group. The mean±standard deviation is expressed as M±SD.t-test values are indicated byt-values (p-values).p< 0.05. 2.2. Intervention Both the experimental and control groups were required to participate in two hours of basketball training each day from Monday to Friday. This training included techni- cal drills and team practice games directed by two basketball coaches, with personnel management overseen by the research team. Additionally, the experimental group under- took a plyometric training program (PTP) twice a week. The intervention measures were as follows. In recent years, many studies have employed plyometric training as a method to en- hance lower-limb
Friday. This training included techni- cal drills and team practice games directed by two basketball coaches, with personnel management overseen by the research team. Additionally, the experimental group under- took a plyometric training program (PTP) twice a week. The intervention measures were as follows. In recent years, many studies have employed plyometric training as a method to en- hance lower-limb strength across various sports [11,23–26]. Based on the existing literature on plyometric training, this study formulated intervention measures for a plyometric train- ing program (PTP). The intervention spanned 12 weeks, as muscle strength adaptations typically require about 12 weeks [27]. The lower-limb plyometric training program, as shown in Table, was conducted twice a week [ 28], and each session lasted 120 min [29]. The lower-limb plyometric training exercises, as listed in Table, were conducted. The experimental group was to undergo PTP twice a week for a total of 12 weeks. Each session was to follow a circuit training format, with each set followed by a 10–30 s rest, and a 3–5 min rest after completing one circuit. A total of three circuits needed to be completed [30]. Each cycle of PTP required a load intensity based on the individual’s maximum strength. Before performing the PTP, each participant in the experimental group was tested for their one-repetition maximum (1RM) for each item, as follows [31]: First circuit: A light load with high repetitions, with each set repeated 12 to 15 times, at 60% to 70% of the 1RM (one-repetition maximum). Second circuit: A moderate load with moderate repetitions, with each set repeated 8 to 10 times, at 70% to 80% of the 1RM (one-repetition maximum). Third circuit: A heavy load with low repetitions, with each set repeated 1 to 5 times, at 80% to 100% of the 1RM (one-repetition maximum).
Appl. Sci.2024,14, 12015 4 of 17 Table 2.Contents of the plyometric training program. Content Reps/Set Warm-up Warm-up with 10 min of aerobic exercise. Dead lift Barbell (10 kg) + weight plates (20 kg) = 30 kg, 15 reps (Set 1) Barbell (10 kg) + weight plates (30 kg) = 40 kg, 10 reps (Set 2) Barbell (10 kg) + weight plates (40 kg) = 50 kg, 1 to 5 reps (Set 3) Skater hops 15 reps each on the left and right (Set 1 to Set 3) Lateral shuffle 15 reps each on the left and right (Set 1 to Set 3) Jumping lunges with dumbbells Dumbbell (6 kg) in each hand, 12 reps (Set 1) Dumbbell (8 kg) in each hand, 8 reps (Set 2) Dumbbell (10 kg) in each hand, 1 to 5 reps (Set 3) Rocket jump 15 reps (Set 1), 10 reps (Set 2), 1 to 5 reps (Set 3) Lateral box jump 6 inches to your side, 10 reps each side (Set 1 to Set 3) The modified single-leg squat (MSLS) Holding a dumbbell in each hand + unilateral (1 leg at a time) training. Dumbbell (6 kg) in each hand, 12 reps (Set 1) Dumbbell (8 kg) in each hand, 8 reps (Set 2) Dumbbell (10 kg) in each hand, 1 to 5 reps (Set 3) The laterally resisted split squat (LRSS) Holding a dumbbell in each hand + laterally split squat (one lunge each to the left and right). Dumbbell (6 kg) in each hand, 12 reps (Set 1) Dumbbell (8 kg) in each hand, 8 reps (Set 2) Dumbbell (10 kg) in each hand, 1 to 5 reps (Set 3) The bilateral back squat (BS) Barbell (10 kg) + weight plates (30 kg) = 40 kg, 12 reps (Set 1) Barbell (10 kg) + weight plates (40 kg) = 50 kg, 8 reps (Set 2) Barbell (10 kg) + weight plates (50 kg) = 60 kg, 1 to 5 reps (Set 3) Box jumps Counter movement jumps Box height: 18 inches, 12 reps (Set 1) Box height: 24 inches, 8 reps (Set
kg) = 40 kg, 12 reps (Set 1) Barbell (10 kg) + weight plates (40 kg) = 50 kg, 8 reps (Set 2) Barbell (10 kg) + weight plates (50 kg) = 60 kg, 1 to 5 reps (Set 3) Box jumps Counter movement jumps Box height: 18 inches, 12 reps (Set 1) Box height: 24 inches, 8 reps (Set 2) Box height: 32 inches, 1 to 5 reps (Set 3) Cool-down Muscle relaxation can be performed with roller stretching or static stretching Based on the PTP measures outlined above, to control the impact of muscle strength enhancement on athletic performance, this study identified the independent and depen- dent variables. Independent Variables: 1. PTP: This includes training frequency, intensity, duration, and exercises (as shown in Table). 2. Muscle Strength Enhancement: Quantified through indicators of muscle strength growth, such as PTP and maximum repetitions. Dependent Variables: 1. Athletic Performance: Specific performance indicators such as vertical jump reaction force, lateral jump resultant force, step-back resultant force, and jump shot accuracy. 2. Sports injury rate: This evaluates the risks of the training plan, helping to reduce the risk of injuries among athletes and improve overall athletic performance. 2.3. Research Tools and Variables 2.3.1. Research Tools This study used the PASCO PS-3230 wireless dual-axis platform, manufactured in Roseville, California, USA. PASCO SCIENTIFIC is a voltage-sensing force plate with product parameters including four corner force elements with a range of±1100 N, and a vertical resultant force up to 4400 N. Each force element has an overload protection of 1700 N, with a total vertical overload protection force of up to 6600 N. The device’s sampling frequency was set to 1000 Hz, allowing for 1000 force measurements per second. The PASCO force plate was used to analyze human jump dynamics, including vertical, lateral, and horizontal jump analysis [32].
Appl. Sci.2024,14, 12015 5 of 17 2.3.2. Research Variables The variables in the study of vertical jumps in basketball athletes include the rate of force development (RFD), ground reaction force (GRF), duration of passage, and jump height. The variables in the study of lateral jumps include the jump distance, horizontal component of ground reaction force (H-GRF), vertical component of ground reaction force (V-GRF), resultant ground reaction force (R-GRF), and trajectory of the resultant force (T-PRF) (θ). The variables in the study of horizontal jumps include the jump distance, maximum slope of left and right foot take-off, horizontal force of step-back take-off (H-GRF), vertical force of step-back landing (V-GRF), resultant force (R-GRF), step-back resultant force trajectory (T-PRF) (θ), and action time of the step-back. 2.4. Test Method 2.4.1. Vertical Jump Test Each participant had 5 test attempts, with a 10 s rest between each attempt. The best three jumps were recorded and averaged to obtain the final score. The parameters measured by the force plate for the vertical jumps included the rate of force development (RFD), ground reaction force (GRF), duration of passage, and jump height. 2.4.2. Lateral Jump Test The participants first practiced lateral jumps on flat ground to determine the optimal force and distance for left and right jumps. Before testing, each participant adjusted their maximum lateral jump distance (the distance at which they could land stably on one foot, which was considered their maximum reasonable distance) [33]. The participants followed a metronome’s pace to perform lateral jumps on one foot, with arm swings allowed. The jump was repeated four times on each foot, and the task had to be completed within 15 s. Finally, the average force exerted by each foot was calculated. The dynamic analysis of lateral jumps using a force plate includes the following variables: jump distance, H-GRF, V-GRF, R-GRF, and T-PRF (θ) [34]. The angle ofθwas calculated. tanθ= length of opposite side (vertical side)/length of adjacent side (horizontal side). When tanθis larger, the angle ofθis larger. 2.4.3. Horizontal Jump Test Each participant first practiced the step-back movement on flat ground to determine the optimal distance
jumps using a force plate includes the following variables: jump distance, H-GRF, V-GRF, R-GRF, and T-PRF (θ) [34]. The angle ofθwas calculated. tanθ= length of opposite side (vertical side)/length of adjacent side (horizontal side). When tanθis larger, the angle ofθis larger. 2.4.3. Horizontal Jump Test Each participant first practiced the step-back movement on flat ground to determine the optimal distance for the step-back take-off. The step-back movement instructions were as follows: The participants stood firmly between two force plates (optimal force position). To initiate the step-back, they stepped forward with their right foot onto the force plate (their left foot was naturally suspended). Upon landing, their right foot pushed back onto the rear force plate. The left foot landed first on the rear force plate, followed by the right foot quickly retracting to achieve a stable posture (alternating between the left and right foot). Each participant performed the step-back movement three times with each foot. The jump distance was determined based on the individual’s optimal performance. The parameters measured by the force plate for horizontal jumps include the jump distance, maximum slope of left and right foot take-off, horizontal force of step-back take- off (H-GRF), vertical force of step-back landing (V-GRF), resultant force (R-GRF), step-back resultant force trajectory (T-PRF) (θ), and action time of the step-back [35]. The angle of θwas calculated. tanθ= length of opposite side (vertical side)/length of adjacent side (horizontal side). When tanθis larger, the angle ofθis larger. 2.4.4. Sports Injury Rate Test The study recruited healthy participants and recorded sports injuries in both the pre- test and post-test phases. These injuries included leg muscle strains, calf cramps, bruises from falls, mild sprains of the ankle or wrist, tendinitis, knee pain, and muscle tension in the back or neck. Initially, the sports injury rate during basketball training and practice games over the previous three months, for both the experimental group and the control
Appl. Sci.2024,14, 12015 6 of 17 group, was surveyed as the pre-test. During the experiment, the sports injury rate for both groups was recorded as the post-test. The sports injury rates for both the pre-test and post-test were standardized to a 12-week (three-month) period. Both the experimental and control groups received basketball training five times per week, for 2 h per session, totaling 120 h. The experimental group additionally underwent plyometric training program (PTP) interventions twice a week, for 2 h per session, totaling 48 h. Therefore, the total training time for the experimental group was 168 h, while the control group’s total training time was 120 h. The specific calculation formula for the sports injury rate was as follows: Sports injury rate = [Number of sports injuries occurring within a certain period/Total training time (hours)]×1000. It is usually expressed per thousand hours of training. 2.4.5. Sports Performance Test The literature indicates that vertical, lateral, and horizontal jump abilities are related to basketball jump shot performance. Therefore, this study tested three types of jump shots: the step-forward vertical jump shot, dominant-side lateral step-up jump shot, and step-back jump shot. The differences between the pre- and post-tests were compared to understand jump shot performance. 2.5. Control Variables Targeted at college-level male basketball athletes from Taiwanese universities, this study recruited participants and noted background variables including age, weight, height, years of athletic experience, and number of sports injuries. These background variables showed homogeneity, and this study’s control variables included dietary control, recovery control, and consistent training conditions. Dietary control involved posting standardized meal plans and providing verbal dietary guidance at the beginning of and throughout the study, to ensure that each participant’s nutrient intake was similar. Recovery control involved requiring the participants to maintain consistent sleep durations and quality, and to record their daily sleep times. Additionally, after each training session, the participants were instructed to perform stretching, massage, and ice therapy for recovery. Because the control group and the experimental group underwent two hours of basketball training simultaneously in the same location, consistent training conditions were ensured. 2.6. Statistical Analysis Statistical
Description
Plyometric training enhances jumping performance and reduces injury rates in college-level male basketball players.