Is a cork a legal shortcut? - A comparison of the measured and assumed amount of rotation in freestyle tricks.

In snowboard freestyle disciplines, the amount of rotation is commonly determined as the sum of rotations around all board axes and is the most important indicator of the trick difficulty across all snowboard freestyle disciplines. Based on the type of rotation, tricks can be classified as flatspins, corks and flips. It is not yet known whether the type of rotation of a trick can influence the actual amount of rotation. Therefore, the aim of this study was to determine the amount of deviation, defined as difference between measured and assumed amount of rotation as a function of trick classification, using kinematic motion analysis. The amount of deviation was positive for flatspins (median: 21°; min: -4°; max: 49°) and negative for corks (median: -25°; min: -89°; max: 12°) and flips (median: -28°; min: -94°; max: 13°). Our results demonstrate that there are ways of execution where riders perform corks and flips with a shortcut and flatspins with a detour. This should be taken into account by judges, coaches and riders. Further research is needed to investigate how the shortcut can be influenced.

A study on the grey relation analysis between the overall performance and individual event scores of international elite trampolinists.

This study applied grey relational analysis to assess the relationship between individual trampoline event scores and overall performance of top male and female athletes in the 2020 Tokyo Olympics. Analyzing execution, horizontal, difficulty, timing of flight, and total scores, results showed males excelled significantly in difficulty, timing, and overall performance, while execution and horizontal scores were comparable. For males, timing of flight (excluding outliers) had the greatest influence on total score, followed by difficulty and execution. In females, difficulty dominated, followed by timing and horizontal, with execution least impactful. The study highlighted the primary roles of timing and difficulty scores in overall trampoline performance, with gender variations in score contributions. The findings illuminated the interplay of score components, offering a theoretical framework for targeted trampoline training. For international athletes, key considerations included boosting height index for a robust trampoline foundation; tailoring difficulty levels to athletes' abilities while adhering to scoring rules, without sacrificing technical prowess; and sustaining training to refine quality and stability of routines.

The Effect of 12 Weeks of Rebound Therapy Exercise Training on Walking Ability of Spinal Cord Injury Patients.

Background: Walking ability is a crucial factor for recovery and rehabilitation of spinal cord injury (SCI) patients. Objectives: The aim of this study was to investigate the effect of 12 weeks of rebound therapy on walking parameters in SCI patients. Methods: Thirty members of Isfahan Spinal Cord Injury Association participated in this experimental study using a convenience sampling method. This study was approved by the ethics committee of the University of Isfahan (IR.UI.REC.1400.118). The participants were randomly assigned to control and rebound groups using a matched randomization method. Data were collected before and after 12 weeks of rebound therapy exercise (three sessions per week) in the walking laboratory, using a seven-camera 3D motion capturing system (Qualisys motion analysis). The final data were analyzed using repeated measures ANOVA in SPSS software (significance level p < .05). Results: Rebound therapy training significantly improved all dependent variables (p < .05) except hip rotation, indicating its effectiveness for enhancing walking ability. Conclusion: Given the importance of walking function, we recommend the use of rebound therapy training as an exercise rehabilitation method for spinal cord injury patients.

Rebound Exercises in Rehabilitation: A Scoping Review.

The term "trampoline" was coined in 1969, introducing a dynamic feedback mechanism for exercise. Rebounding exercise on a mini-trampoline utilizes an elastic surface supported by springs and gravity, potentially reducing cumulative trauma from repetitive loading. This type of physical activity provides enjoyable and engaging exercise for adolescents, especially those who are overweight, thereby reducing the likelihood of injuries associated with exercise. Mini-trampoline exercises enhance blood circulation, oxygen delivery, and bone health, impacting lower limb strength, balance, motor performance, blood glucose levels, executive function, physiological markers, and overall quality of life. The study focused on examining the overall impact of rebounding exercises in the field of rehabilitation. Its main goal was to assess how these exercises affect the rehabilitation process and different health measures. By investigating the comprehensive influence of rebounding exercises, the study aimed to determine their effectiveness in aiding physical and functional recovery, targeting specific rehabilitation goals, and enhancing overall health outcomes. We systematically reviewed medical literature databases such as PubMed, MEDLINE, Scopus, Google Scholar, and EBSCO. We included research articles, systematic reviews, meta-analyses, clinical trials, case studies, and observational studies published in English up to 10 years before the review's cutoff in December 2023. We considered participants across all age groups. Articles not in English were excluded from the review. The outcome measures were body composition, waist-hip ratio, Bruininks-Oseretsky test for motor proficiency, reaction time, insulin resistance, lipid profile, blood cholesterol level, forced expiratory volume in one second, and forced vital capacity, bone health indicators, blood lactate level, balance, strength: repetitive maximum, brief pain inventory (short form). A total of 11 reports met these criteria. In conclusion, this review provides a thorough look into the use, challenges, and future potential of rebound exercises in rehabilitation and fitness. Despite their wide-ranging applications, issues such as insufficient research, equipment variability, and safety concerns persist. Advancement requires more research for evidence-based guidelines, improved equipment design and safety measures, and collaboration among researchers, clinicians, and manufacturers. Overcoming challenges and fostering innovation can establish rebound exercises as a valuable tool in rehabilitation and fitness.

A Review of 13,470 Head and Neck Injuries from Trampoline Jumping.

Study Design: The authors designed a 20-year cross-sectional study using the National Electronic Injury Surveillance System (NEISS) database. Objective: The purpose of the study is to determine the risk factors for hospital admission among individuals who suffer head and neck injuries secondary to trampoline use. Methods: The primary predictor variables were a set of heterogenous variables that were categorized into the forementioned study variable groups (patient characteristics and injury characteristics). The primary outcome variable was hospital admission. Multivariate logistic regression was used to determine independent risk factors for hospital admission. Results: The final sample consisted of 13,474 reports of trampoline injuries to the head and neck. Relative to females, males (OR 1.66, P < .05) were at an increased risk for hospital admissions. Fractures (OR 35.23, P < .05) increased the risk for hospital admissions relative to dental injuries. Concerning anatomical region of injury, neck injuries (OR 30.53, P < .05) were at an increased risk for hospital admissions. Conclusions: Injuries to the neck from trampoline jumping significantly increased the risk for admission. The severity of neck injuries from trampoline jumping is well established in the literature. Additionally, male sex and fractures were each risk factors for hospital admission. Given the rising prevalence of trampoline-related head and neck injuries over the past 2 decades, it is crucial for individuals to take the necessary precautions when jumping on a trampoline.

Changing Sleep Architecture through Motor Learning: Influences of a Trampoline Session on REM Sleep Parameters.

Previous research has shown that learning procedural tasks enhances REM sleep the following night. Here, we investigate whether complex motor learning affects sleep architecture. An experiment in which twenty-two subjects either learned a motor task (trampolining) or engaged in a control task (ergometer) was carried out in a balanced within-group design. After an initial laboratory adaptation night, two experimental nights were consecutive. The results indicate that learning a motor task had an effect on REM sleep parameters and, therefore, support the hypothesis that learning a procedural skill is related to an increase in REM sleep parameters. However, the statistical effect on REM sleep is smaller than found in previous studies. One might speculate that the motor learning was not intense enough compared to other studies. For sports practice, the results suggest that REM sleep, which is particularly rich in the morning, plays an important role in motor memory consolidation. Thus, this phase should not be interrupted after complex motor skill learning sessions. In future studies, other motor tasks should be applied.

Trampoline Stiffness Estimation by Using Robotic System for Quantitative Evaluation of Jumping Exercises.

Trampolines are recognized as a valuable tool in exercise and rehabilitation due to their unique properties like elasticity, rebound force, low-impact exercise, and enhancement of posture, balance, and cardiopulmonary function. To quantitatively assess the effects of trampoline exercises, it is essential to estimate factors such as stiffness, elements influencing jump dynamics, and user safety. Previous studies assessing trampoline characteristics had limitations in performing repetitive experiments at various locations on the trampoline. Therefore, this research introduces a robotic system equipped with foot-shaped jigs to evaluate trampoline stiffness and quantitatively measure exercise effects. This system, through automated, repetitive movements at various locations on the trampoline, accurately measures the elastic coefficient and vertical forces. The robot maneuvers based on the coordinates of the trampoline, as determined by its torque and position sensors. The force sensor measures data related to the force exerted, along with the vertical force data at X, Y, and Z coordinates. The model's accuracy was evaluated using linear regression based on Hooke's Law, with Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and Correlation Coefficient Squared (R-squared) metrics. In the analysis including only the distance between X and the foot-shaped jigs, the average MAE, RMSE, and R-squared values were 17.9702, 21.7226, and 0.9840, respectively. Notably, expanding the model to include distances in X, Y, and between the foot-shaped jigs resulted in a decrease in MAE to 15.7347, RMSE to 18.8226, and an increase in R-squared to 0.9854. The integrated model, including distances in X, Y, and between the foot-shaped jigs, showed improved predictive capability with lower MAE and RMSE and higher R-squared, indicating its effectiveness in more accurately predicting trampoline dynamics, vital in fitness and rehabilitation fields.

Differences in Trampoline-Related Knee Injuries Between Children and Adults: A Cross-Sectional Study.

Background: Little is known about the specific risk of knee injuries due to trampoline accidents in adults compared with children. Purpose: To investigate the differences in trampoline-related knee injuries between children and adults and identify risk factors and protective strategies to reduce injury incidence. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Data on 229 consecutive patients treated for trampoline-related knee injuries in a single institution were prospectively collected, analyzed, and included. Risk factors, injury patterns, and clinical treatments were compared between skeletally immature and skeletally mature patients. Logistic regression was used to determine the odds ratios for specific risk factors for trampoline-related injuries-including body mass index (BMI), trauma mechanism, patient age, and accident location. Results: A total of 229 patients met the inclusion criteria; 118 (52%) patients (women, 54.2%; mean age, 8.5 ± 4.1 years) were skeletally immature at the time of injury, and 111 (48%) patients (women, 72%; mean age, 31.9 ± 13.1 years) had closed physes on initial presentation and were classified as skeletally mature. A total of 63 patients (28%) required surgical treatment for their knee injury. Overall, 50 anterior cruciate ligament (ACL) tears, 46 fractures, 39 meniscal tears, 31 ligamentous tears other than ACL, 22 patellar dislocations, and 38 soft tissue injuries, such as lacerations, were recorded. Skeletally mature patients had 7.8 times higher odds (95% CI, 1.6-46.8; P < .05) and 19.1 increased odds (95% CI, 5.5-74.9; P < .05) of an ACL tear or another ligamentous tear, respectively, compared with skeletally immature patients. Patients who described instability and giving way of the knee as relevant trauma mechanisms had odds of 3.11 (95% CI, 0.9-14.8; P < .05) of an ACL tear compared with other trauma mechanisms. Meniscal tears were observed more frequently in the skeletally mature cohort (P < .05). An elevated BMI was associated with a significantly higher relative risk of an ACL tear, a ligamentous tear other than the ACL, and an injury requiring surgery. A third of surgically treated patients were subject to a delayed diagnosis. Conclusion: Adults had a significantly increased risk of ligamentous and meniscal tears and required operative intervention more often than skeletally immature individuals. Elevated BMI, age, and instability events in terms of trauma mechanism conveyed an increased risk of structural damage to the knee.

Mid-Thoracic Vertebral Compression Fracture after Mini-Trampoline Exercise: A Case Series of Seven Patients.

Background and Objectives: Home-based training exercise gained popularity during the coronavirus disease 2019 pandemic era. Mini-trampoline exercise (MTE) is a home-based exercise that utilizes rebound force generated from the trampoline net and the motion of the joints of the lower extremities. It is known to be beneficial for improving postural balance, stability, muscle strength and coordination, bone strength, and overall health. However, we encountered several patients with mid-thoracic vertebral compression fractures (VCFs) following regular MTE, which was never reported previously, despite having no history of definite trauma. This study aims to report mid-thoracic VCFs after regular MTE and arouse public attention regarding this spinal injury and the necessity of appropriate prior instructions about the correct posture. Patients and Methods: All consecutive patients diagnosed with acute VCFs following regular MTE were included. We collected data on patient demographics, history of MTE, characteristics of symptoms, and radiological findings such as the location of fractures and anterior vertebral body compression percentage. Results: Seven patients (one man and six women) and ten fractures (T5 = 1, T6 = 3, T7 = 2, and T8 = 4) were identified. Symptoms started 2.57 ± 1.13 weeks after the beginning of regular MTE. All patients reported that they were never properly instructed on the correct posture. They also stated that they were exercising with a hunchback posture and insufficient joint motion of the lower extremities while holding the safety bar with both hands, which resulted in increased peak vertical force along the gravity z-axis in the mid-thoracic area and consequent mid-thoracic VCFs. Conclusions: Mid-thoracic VCFs can occur following regular MTE even without high-energy trauma in case of improper posture during exercise. Therefore, public attention on mid-thoracic VCFs following MTE and the appropriate prior instructions are imperative.

Trampoline-Associated Cranial and Spinal Injuries: A 10-Year Study in a Pediatric Neurosurgery Center.

OBJECTIVE:  There has been an increasing use of trampolines for recreation by children in recent years. Many studies have explored the different types of injuries sustained due to falls from trampolines, but so far none have focused specifically on cranial and spinal injuries. In this study, we describe the pattern of cranial and spinal injuries sustained by pediatric patients that were associated with the use of trampolines and their management in a tertiary pediatric neurosurgery unit over a period of 10 years. METHODS:  This is a retrospective study of all children less than 16 years of age with suspected or confirmed trampoline-associated cranial or spinal injuries, managed by a tertiary pediatric neurosurgery unit from 2010 to 2020. Data collected included the patient's age at the time of injury, gender, neurological deficits, radiological findings, management, and clinical outcome. The data were analyzed to highlight any trends in the pattern of injuries. RESULTS:  A total of 44 patients with a mean age of 8 years (ranging from one year and five months to 15 years and five months) were identified. 52% patients were male. 10 patients (23%) had a reduced Glasgow Coma Scale (GCS) score. In terms of imaging findings, 19 patients (43%) had a radiologically positive head injury, nine (20%) had a craniovertebral junction (CVJ) injury, including the first (C1) and second (C2) cervical vertebrae, and six (14%) had an injury involving other parts of the spine. No patient sustained concurrent head and spinal injuries. Eight (18%) patients had normal radiological findings. Two (5%) had incidental findings on radiology that required subsequent surgery. A total of 31 patients (70%) were managed conservatively. 11 patients (25%) underwent surgery for their trauma, of which seven were cranial. Two further patients underwent surgery for their incidental intracranial diagnoses. One child died from an acute subdural hemorrhage. CONCLUSIONS:  This study is the first to focus on trampoline-associated neurosurgical trauma and report the pattern and severity of cranial and spinal injuries. Younger children (less than five years of age) are more likely to develop a head injury, whereas older children (more than 11 years of age) are more likely to develop a spinal injury following the use of a trampoline. Although uncommon, some injuries are severe and require surgical intervention. Therefore, trampolines should be used prudently with the appropriate safety precautions and measures.

Effects of eight week core stability training on stable- and unstable-surface on ankle muscular strength, proprioception, and dorsiflexion in athletes with chronic ankle instability.

BACKGROUND: Chronic ankle instability (CAI) is a common injury among athletes. Research has reported reduced dorsiflexion range of motion, impairment of proprioception, and decreased muscle strength of the ankle in people with CAI. The aim of this research was to examine the effects of 8-week core stability training on stable and unstable surfaces on ankle muscular strength, proprioception, and dorsiflexion range of motion (ROM) in athletes with CAI. METHODS: Thirty-six athletes with CAI (age 22.42 ± 2.76 years; height 169.11 ± 3.52 cm; weight 68.46 ± 2.75 kg) participated in this study. They were divided into three groups: unstable-surface group (UG) (n = 12), stable-surface group (SG) (n = 12), and control group (CG) (n = 12). The UG and SG performed the core stability exercise protocol for 8 weeks, 3 sessions per week. The CG received their usual care and daily activities. Outcomes were measured pre-sessions and post-sessions. RESULTS: The peak torque showed significant increases in the UG and SG compared with the CG during plantar flexion, dorsiflexion, inversion, and eversion (P < 0.05). There were also significant increases in UG compared with SG (P < 0.05). The proprioception showed significant decreases in UG compared with SG and CG (P < 0.05). The dorsiflexion ROM showed significant increases in UG and SG compared with CG. There were also significant increases in UG compared with SG (P < 0.05). CONCLUSIONS: It seems that core stability exercises on trampoline surface helps improve the measured parameters in athletes with ankle instability. Therefore, this type of training is recommended as a therapeutic option for Individuals with CAI.

Road Traffic Accidents, Climbing Frames, or Trampolines: What Harms Children in the 2020s?

Background In the modern Western world, activities and the daily routine of children have changed over time. Detailed analyses of the mechanisms of injuries and current fracture patterns in children are rare. The aim of the study was to elicit and investigate the most dangerous leisure and sporting activities leading to fractures in children today. Materials and methods This is a retrospective study focusing on children that were treated in a level-one trauma center in Germany between 2015 and 2020. All children who were 14 years of age or younger and suffered a traumatic injury treated in our emergency department were included in this study. From the database, mechanisms of injury, type of injury, age, and gender were analyzed. Results The study included 12508 patients, including 7302 males and 5206 females. Among the 10 most common mechanisms of injury were collisions (8.6%), falls (7.7%), injuries while playing (6.1%) or while running or walking (5.9%), soccer (5.9%), bicycle accidents (3.8%), and trampoline falls (3.4%). Road traffic accidents involving passengers or pedestrians caused 3.3% of the injuries but were the most common cause of death. The most common mechanisms of injury causing a fracture were falls, playing soccer, and bicycle accidents. Sorting the mechanisms of injury by the percentage that caused a fracture, the most dangerous activities were falling from heights above 2 meters, skiing and snowboarding, climbing and bouldering, skateboarding, and horseback riding. In the five-year study period, four out of six children died due to road traffic accidents. Conclusion Injured children must be provided with the best quality of care 24/7 in orthopedic trauma departments and have to be kept as a focus in the training of orthopedic trauma surgeons. Road traffic accidents are still the main cause of death in children, but they are overall less common. Falls and sports activities are the most likely to cause a fracture.

Partial Remodeling after Conservative Treatment of Trampoline Fractures in Children.

(1) Background: Trampoline fractures (proximal tibia fracture with positive anterior tilt) are increasing. This study represents the first attempt to determine the extent of remodeling in these fractures after conservative treatment (2) Methods: This Swiss prospective multicenter study included children aged 2 to 5 years with a trampoline fracture who were radiologically examined on the day of the accident and after one year. In addition, the anterior tilt angle was compared between the injured and unaffected tibia. Remodeling was defined as complete (final anterior tilt angle ≤ 0°), incomplete (smaller but still >0°), or no remodeling. (3) Results: The mean extent of remodeling was -3.5° (95% CI: -4.29°, -2.66°, p < 0.001). Among the 89 children included in the study, 26 (29.2%) showed complete, 63 (70.8%) incomplete, and 17 patients (19.1%) no remodeling. Comparison of the anterior tilt angles between the fractured and healthy tibia showed that the anterior tilt angle on the fractured leg was, on average larger by 2.82° (95% CI: 2.01°, 3.63°; p < 0.001). (4) Conclusions: Although the anterior tilt angle decreased during the study period, the majority of patients showed incomplete remodeling. In contrast, children with radiological examinations >1 year after the trauma showed advanced remodeling, suggesting that one year is too short to observe complete remodeling.

Lisbon Intensive Falls Trampoline Training (LIFTT) Program for people with Parkinson's for balance, gait, and falls: study protocol for a randomized controlled trial.

BACKGROUND: Falling and gait difficulties in people with Parkinson's disease (PD) are associated with impaired reactive postural adjustments and impairments in attentional resources. Combined intensive balance motor and cognitive exercise can be beneficial. However, uncertainties persist regarding the true effects and safety when applying such training. Using trampoline beds may be a favorable safe environment for a highly intensive, cognitive, and balancing training approach. The primary goal of this randomized controlled trial is to assess the effects of an intensive cognitive-motor training program in a safe trampoline environment in addition to usual care on balance impairment, gait, physical capacity, fear of falling, falls frequency and severity, cognition, and clinical impairments in people with mild or moderate PD. METHODS: Sixty participants diagnosed with idiopathic PD, in stage 2-4 Hoehn and Yahr, with a clinical history of gait deficits and a fall history (at least one fall in the last 6 months) will be recruited and randomly allocated to an intervention group receiving cognitive-motor trampoline training or a control group undergoing their usual care. The intervention will consist of 8-week individual training sessions (1-h training, 3 days per week) led by specialized physiotherapists that will provide progressive, challenging training, and guarantee safety. Assessment will be conducted prior to and immediately after the 8-week intervention and at 3 months follow-up after participating in the study. Primary outcome measures will be balance performance (assessed using the Mini-BEST Test and nonlinear analysis) and change in gait parameters (Motor and Cognitive Timed-Up-Go and nonlinear analysis). Secondary outcomes will be change in clinical improvement (Movement Disorder Society Unified Parkinson's Disease Rating Scale), falls (falls weekly registry), fear of falling (assessed using the Falls Efficacy Scale), physical capacity (6-min walk test), and cognition (Montreal Cognitive Assessment). DISCUSSION: This study will provide new evidence on the benefits of intensive cognitive-motor balance training on a trampoline for people living with PD. Better guidance on how professionals can apply safer dual-task balance and gait training in rehabilitation is needed. TRIAL REGISTRATION: ISRCTN Registry ISRCTN13160409 . Retrospectively registered on February 23, 2022.

A Public Health Review into Two Decades of Domestic Trampoline Injuries in Children within Queensland, Australia.

Trampolining as an activity brings enjoyment and many health benefits, but at the same time it carries an injury risk. Most domestic trampoline users are children who are developing in skill, cognition, risk perception, physical strength and resilience to injury. Several common patterns of child trampoline injuries have been identified and countermeasures outlined in standards have been taken to reduce higher risk injury mechanisms, such as entrapment and falls from the trampoline through design, product and point of sale labelling. In Australia, the first national trampoline standard was published in 2003 which introduced improvements in trampoline design and requirements for labelling and padding. This work investigated the potential impact of these and subsequent changes based on almost two decades of emergency department trampoline injury data collected in Queensland, Australia. These data describe the changing representative proportion and pattern of trampoline injuries in Queensland over time by age, mechanism, gender, severity and nature of injury of injured persons up to the age of 14 years. The interrelationships between different injury characteristics were also analysed to propose the main factors influencing injury occurrence and severity. These findings seem to indicate that safety evolution in the form of enclosure nets, frame impact attenuation and entrapment protection have likely improved domestic trampoline safety. Other factors, such as adult supervision, minimum age and avoidance of multiple users, could further reduce injury but are harder to influence in the domestic setting.

Three-Dimensional Foot Position Estimation Based on Footprint Shadow Image Processing and Deep Learning for Smart Trampoline Fitness System.

In the wake of COVID-19, the digital fitness market combining health equipment and ICT technologies is experiencing unexpected high growth. A smart trampoline fitness system is a new representative home exercise equipment for muscle strengthening and rehabilitation exercises. Recognizing the motions of the user and evaluating user activity is critical for implementing its self-guided exercising system. This study aimed to estimate the three-dimensional positions of the user's foot using deep learning-based image processing algorithms for footprint shadow images acquired from the system. The proposed system comprises a jumping fitness trampoline; an upward-looking camera with a wide-angle and fish-eye lens; and an embedded board to process deep learning algorithms. Compared with our previous approach, which suffered from a geometric calibration process, a camera calibration method for highly distorted images, and algorithmic sensitivity to environmental changes such as illumination conditions, the proposed deep learning algorithm utilizes end-to-end learning without calibration. The network is configured with a modified Fast-RCNN based on ResNet-50, where the region proposal network is modified to process location regression different from box regression. To verify the effectiveness and accuracy of the proposed algorithm, a series of experiments are performed using a prototype system with a robotic manipulator to handle a foot mockup. The three root mean square errors corresponding to X, Y, and Z directions were revealed to be 8.32, 15.14, and 4.05 mm, respectively. Thus, the system can be utilized for motion recognition and performance evaluation of jumping exercises.

Trampoline Use and Retinal Detachment in Stickler Syndrome.

Stickler syndrome is one of the most common inherited causes of retinal detachment in childhood. We present the case of a 6-year-old boy with Stickler syndrome who developed a retinal detachment in his better seeing eye after prolonged trampoline use. We suggest that trampolining should be avoided in all patients at increased risk of retinal detachment, especially in Stickler syndrome, and in those with other risk factors including high myopia and previous retinal detachments.

Investigation into the Trampoline Dynamic Characteristics and Analysis of Double Bounce Vibrations.

Double bounce is an unusual and potentially very hazardous phenomenon that most trampoline users may have experienced, yet few would have really understood how and why it occurs. This paper provides an in-depth investigation into the double bounce. Firstly, the static and dynamic characteristics of a recreational trampoline are analysed theoretically and verified through experiments. Then, based on the developed trampoline dynamic model, double bounce simulation is conducted with two medicine balls released with different time delays. Through simulation, the process of double bounce is presented in detail, which comprehensively reveals how energy is transferred between users during double bounce. Furthermore, the effect of release time delay on double bounce is also presented. Finally, we conducted an experiment which produced similar results to the simulation and validated the reliability of the trampoline dynamic model and double bounce theoretical analysis.