Abstract
ackward running is common in handball defense and relies heavily on proprioceptive control when visual information is limited. Twenty-eight male handball players were allocated to three groups: experimental novice group with blindfold training(n =7), control novice group with the same training without blindfold (n =7), and target pro- fessional group(n =14). Both novice groups completed a 6-week balance program (3×20 min/week ). Lower-limb kinematics during backward running were captured with a 6-camera motion analysis system, and inter-joint coordination was quantified by Mean Absolute Relative Phase (MARP) and Deviation Phase (DP) for ankle–knee and knee–pelvic couplings. At baseline, professionals showed greater ankle–knee MARP than novices (ANOVA F(2,25) = 9.42,p< 0.001). Representative means (mean±SD): ankle–knee MARP novices 1.62–1.79 vs. professionals 3.83. After training, ankle–knee MARP increased in both novice groups (experimental: t(6) = 4.72,p< 0.001; control: t(6) = 5.02,p< 0.001), approach- ing professional values (post-training novices≈3.22–3.26). Post-training between-group differences were non-significant for ankle–knee MARP (ANOVA F(2,25) = 1.24,p= 0.30), while ankle–knee DP showed a group effect (F(2,25) = 5.12,p= 0.01; experimental vs. professionalt(19) = 3.12,p= 0.01). A short-term balance program improved ankle–knee coordination during backward running in novice male players; additional blindfolding did not yield extra benefit over 6 weeks. These findings can inform
(post-training novices≈3.22–3.26). Post-training between-group differences were non-significant for ankle–knee MARP (ANOVA F(2,25) = 1.24,p= 0.30), while ankle–knee DP showed a group effect (F(2,25) = 5.12,p= 0.01; experimental vs. professionalt(19) = 3.12,p= 0.01). A short-term balance program improved ankle–knee coordination during backward running in novice male players; additional blindfolding did not yield extra benefit over 6 weeks. These findings can inform short-term training and rehabilitation planning for handball, while long-term effects require future study. Keywords:bionics; blindfolded balancing; handball; handball action; kinematics; backward running 1. Introduction Handball is a team sport that has been played professionally since 1946. Handball is an energetic and physically challenging sport that needs exceptional agility, strength, and balance. The incidence of injuries in this activity, similar to many other physical sports, is significantly elevated and typically entails substantial financial burdens for organizations and athletes. Recent research indicates that injury rates among youth handball players vary from 9.9 to 41 injuries per 1000 h of competition and from 0.9 to 2.6 injuries per 1000 h of practice [1]. The essential skills for this sport encompass rapid movements, backward running, and coordination under dynamic conditions. Backward running, in particular, is fundamental Biomimetics2025,10, 649 https://doi.org/10.3390/biomimetics10100649
Biomimetics2025,10, 649 2 of 22 for defensive maneuvers, allowing players to retreat quickly while maintaining visual contact with the ball and opponents [2]. In recent years, researchers have been endeavoring to discover efficacious methods to avert the incidence of musculoskeletal injuries, taking into account the expenses and repercussions associated with such accidents in sports [3]. An approach explored in recent studies is the examination of athletes’ gait. Motion analysis can be conducted by employing instruments that quantify movement, mechanics, muscle activity, as well as the ocular and cerebral functions within the human body. Gait analysis is employed to evaluate the locomotion patterns of individuals [4]. Previous studies have applied gait and motion analysis to investigate athletes’ move- ment patterns and to identify factors related to injury risk. These methods provide detailed kinematic data that highlight deficiencies in inter-joint coordination and neuromuscular control. In the context of handball, analyzing gait during backward running is especially relevant, as it can reveal risk factors for knee and ankle injuries and guide the development of preventive training approaches such as blindfolded balance training [5,6]. 1.1. Previous Studies on Backward Running in Handball Among the various movements of handball athletes, backward movements in which the person is forward but runs backwards, and, in this case, does not have enough control over the body and the environment, the probability of injury is very high [7]. For this reason, this topic has been of great importance among researchers in this field in recent years. Chaudhary proved in his field study that backward running in handball increases the probability of injury in athletes [8]. Also, Kaparos et al. [9] proved the possibility of increased risk and injury among basketball athletes who run backward and look forward. This situation occurs when the athlete runs back in a defensive position (when the opposing team is in a counter-attacking position). In this situation, because the athlete wants to have the best reaction in front of the opposing team and track the ball’s route, he avoids looking back and goes backwards due to the depth of the playing field and the placement
occurs when the athlete runs back in a defensive position (when the opposing team is in a counter-attacking position). In this situation, because the athlete wants to have the best reaction in front of the opposing team and track the ball’s route, he avoids looking back and goes backwards due to the depth of the playing field and the placement of other players in different locations. Scientifically, backward running has different biomechanical characteristics than running forward [10–12]. Proprioception, the sense of movement and joint position, plays a critical role in maintaining coordination during dynamic skills such as backward running. Under conditions of visual deprivation, such as blindfolded training, athletes rely more heavily on proprioceptive cues, making this aspect directly relevant to the present study [13,14]. Effective sensorimotor integration relies on the dynamic interplay of visual, vestibular, and proprioceptive systems. While visual input often guides postural control and move- ment, manipulating or reducing vision can actively encourage the sensorimotor system to re-weight inputs in favor of proprioceptive and vestibular feedback, potentially enhancing motor control strategies. Recent literature highlights the pivotal role of proprioceptive en- hancement within sports science and rehabilitation contexts. An editorial by Rojas-Valverde et al. [15] emphasizes the central function of proprioception for postural regulation, athletic performance, and injury prevention. In addition, a systematic review and meta-analysis by Majelan et al. [16] found that proprioceptive training significantly improves postural balance in athletes recovering from anterior cruciate ligament reconstruction, indicating that proprioceptive-based interventions yield substantial practical benefits. Moreover, research exploring sensory re-weighting mechanisms under visual deprivation has gained momentum. For example, Sung et al. [17] investigated how visual constraints influence postural sway within defined spatial boundaries, offering insight into how sensory input modulations impact stability and motor adaptation. These findings collectively support the theoretical rationale for employing balancing blindfold training in handball. By selectively depriving visual input, athletes are compelled to refine proprioceptive and vestibular
Biomimetics2025,10, 649 3 of 22 coordination, which may enhance dynamic control, adaptability, and resilience during backward running—particularly in scenarios where direct visual feedback is limited. Recently, there have been limited studies on backward running in handball players, which are described below. In a study, Sammoud et al. [18] randomly assigned 29 female handball players to three groups: forward running, backward running, and a control group. After 8 weeks of training, both training groups showed significant improvements in muscle strength, running speed, ability to change direction, and repeated running ability. However, backward running training had slightly greater improvements in 10 m running speed and change direction speed than forward running training. Uthoff et al. [19] showed in a study that backward running training can help improve forward running and vertical jump performance in adolescent athletes. Their training also helped improve running economy and cardiorespiratory function. These studies suggest that backward running training can help improve the physical performance of handball players and may have more benefits than forward running training in some aspects. Abdulrazzaq et al. [20] evaluated the effect of a specific training program on improving motor reaction speed, increasing motor satis- faction, and improving short-term defensive skills in handball players. An experimental method was used to evaluate the effectiveness of the training program in this study. This study showed that a specific training program can effectively improve the motor perfor- mance of handball players. Implementing such programs can be effective in developing defensive skills and increasing the motor satisfaction of players. Hadjisavvas et al. [21] investigated the effect of posture and body composition on stability and motor performance of professional handball players in a study titled The Importance of Posture and Body Composition for Stability and Selected Motor Abilities of Professional Handball Players. The aim of this study was to analyze the body composition, posture, and postural stability of professional male handball players and determine the differences between players with correct and incorrect posture. Also, the effect of these factors on lower limb strength, agility, speed, and directional change deficits was investigated. The researchers concluded that incorporating postural retraining
of Professional Handball Players. The aim of this study was to analyze the body composition, posture, and postural stability of professional male handball players and determine the differences between players with correct and incorrect posture. Also, the effect of these factors on lower limb strength, agility, speed, and directional change deficits was investigated. The researchers concluded that incorporating postural retraining exercises into training programs is essential to improve balance and motor performance of handball players. Among the joints of the body, the ankle is of particular importance due to the weight bearing of the body and the variety of movements. This joint provides movement and strength of the ankle joint with the help of soft tissue and ligaments around it. As a result, the current study examines the kinematics of the lower limbs of professional and novice athletes during movement, as backward running, with the help of the degree of coordination of movement between joints based on the phase difference, to determine the effectiveness of balance exercises using blindfolds. In other words, by determining movement indicators such as speed, linear and angular acceleration in looking forward and backward running, the correct model of backward running movement is tried to be presented to handball coaches and athletes. 1.2. Objectives and Hypotheses of the Present Study Based on the theoretical background and previous findings, the following hypotheses were formulated: (1) Blindfold training will significantly enhance motor coordination in novice handball players by increasing reliance on proprioceptive feedback, as reflected in MARP indices. (2) Professional handball players will exhibit smaller improvements, since their coordination and proprioceptive abilities are already well developed. (3) Blind- fold training will not provide additional benefits compared to traditional training when comparing the two novice groups (test vs. control). The aim of this study was to form 3 different groups of novice and professional handball players in the form of experimental, control, and target group to determine the effect of using a balance blindfold and training sessions on the backward movement of
The aim of this study was to form 3 different groups of novice and professional handball players in the form of experimental, control, and target group to determine the effect of using a balance blindfold and training sessions on the backward movement of
Biomimetics2025,10, 649 4 of 22 handball players. Therefore, to carry out this research, the following assumptions can be considered: a. There is a difference between the movement patterns of professional and novice backward running. b. Fatigue affects the movement pattern of professional and novice athletes in back- ward running c. The ability to control and coordinate ankle movements is different in novice athletes. d.The motor neuron system of novice athletes works differently in dealing with the environment. In this study, we aim to answer the following questions: A.Can using a balance blindfold be effective in backward movement? B. Can using training sessions be effective in improving the backward movement of novice handball players? 2. Experimental Procedures and Techniques This section provides a detailed explanation of the research methodology, includ- ing topics such as the statistical sample, statistical sampling, data collection methods, measuring tools, variable measurement techniques, and statistical analysis methods. 2.1. Database The educational data collection was conducted in the laboratory of physiological signal processing, located in the Faculty of Electrical Engineering at the Tehran branch of Islamic Azad University. Prior to the experiment, all participants were required to verify and endorse the informed consent form in order to partake in the experiment. The data registration for this project has received approval from the university’s ethical committee under the code IR.1401.6. According to the Cochran equation, a total of twenty- eight male athletes were involved in this experiment, divided into three distinct groups. The initial and subsequent groups consisted of seven novice handball players, while the third group comprised fourteen skilled handball players. All 28 participants were male handball athletes. To ensure participants’ suitability for the study, all athletes completed a health and in- jury screening questionnaire before enrollment. None of the participants reported a history of orthopedic, neurological, or neuromuscular disorders, nor any musculoskeletal injuries in the six months preceding the study. In addition, athletes with 2–5 years of handball training experience were excluded to ensure a clear contrast between novice (<2 years) and professional (≥5 years) groups. The novice participants were active in recreational or university-level handball teams,
of the participants reported a history of orthopedic, neurological, or neuromuscular disorders, nor any musculoskeletal injuries in the six months preceding the study. In addition, athletes with 2–5 years of handball training experience were excluded to ensure a clear contrast between novice (<2 years) and professional (≥5 years) groups. The novice participants were active in recreational or university-level handball teams, while professional participants were recruited from athletes with continuous competitive training and participation in regional or national leagues. The novice groups (Control group and Test group) consisted of athletes with less than two years of formal training experience, whereas the professional group (Target group) consisted of athletes with at least five years of continuous competitive training. Demographic characteristics, including mean age, height, weight, and body mass index (BMI), are presented in Table. Table 1.Demographic characteristics of study participants. Group n Age (Years) Height (m) Weight (kg) BMI Gender Training Experience Group #1 (Novice) 7 21 1.70 75 25.95 Male <2 years Group #2 (Novice) 7 22 1.75 73 23.83 Male <2 years
Biomimetics2025,10, 649 5 of 22 Table 1.Cont. Group n Age (Years) Height (m) Weight (kg) BMI Gender Training Experience Group #3 (professional) 14 21 1.72 74 24.01 Male ≥5 years Mean - 21.3 1.72 74 24.60 Male - Std. Deviation - - 0.02 0.81 0.95 - - The initial stage (pre-test) involved administering the backward running test to all individuals from the three groups. In addition, the motion analysis system was used to record the movement of markers placed on the athlete’s body. The system then estimated the movement angles of the ankle, knee, and thigh joints of the supporting leg for athletes in all three groups, namely in the sagittal plane. Following the initial test, both the first and second test groups engaged in a standardized balance training program for a duration of six weeks. Each group participated in three sessions per week, with each session lasting approximately 20 min, resulting in a total of 18 sessions (≈360 min). The training content included single-leg stance exercises, tandem walking, and backward running drills performed on stable surfaces. All sessions were carried out in the motion analysis laboratory under the supervision of a certified coach. Throughout the intervention, participants were instructed not to engage in additional structured handball training or resistance exercise programs outside of the prescribed sessions. Moreover, none of the participants sustained injuries or interruptions during the six-week intervention, and adherence to the training sessions was 100% across groups. The test group performed all drills while blindfolded to reduce their reliance on visual cues, whereas the control group completed the same exercises with normal vision. The third group of professional athletes was studied as the target group. To minimize potential confounding factors, participants were instructed to maintain their regular diet, refrain from additional structured physical training, and avoid stimulant consumption 24 h before each testing session. Moreover, all training sessions were conducted at the same time of day to control for circadian influences. Following the completion of the training course for both groups, the backward running test was repeated, and all data recording and index calculation procedures were repeated.
diet, refrain from additional structured physical training, and avoid stimulant consumption 24 h before each testing session. Moreover, all training sessions were conducted at the same time of day to control for circadian influences. Following the completion of the training course for both groups, the backward running test was repeated, and all data recording and index calculation procedures were repeated. In this study, a total of 18 markers were placed on the lower limbs of all athletes during the initial stage (pre-test) and while running in reverse. Figure various body areas of the athletes. Toe Marker Ankle Marker Knee Marker Hip Marker Figure 1.Shows how the markers are placed on different areas of the body.
Biomimetics2025,10, 649 6 of 22 The system calibration operation is necessary to enable the usage of cameras, accurately position individuals, and obtain reliable data from the indicators. In order to calibrate, a T-shaped instrument known as a “wand” is employed, which moves continuously within the areas covered by all six cameras until each camera registers a green calibration mark in the software. For the next step, the wand is placed in the center of the screen until all 6 cameras detect the device. Figure Figure 2.The calibrating equipment utilized throughout the experiment. Following the calibration and marking of the markers on the athlete’s body, a folder named individual was created in the VICON NEXUS software (version 2.9). This software’s measurement section includes the desired items for the lower body, such as height, weight, leg length (from the waist to the heel), and the distance between the lateral bones of the patella and ankle. Following that, the individual is placed on the screen and in front of the camera, and static tests are conducted on him for 15 s. In the calibration phase, the wand is placed on the force plate to precisely calculate the static component without noise. Figure depicts the static test method on one of the athletes. Figure 3.A view of the athlete during the static test. After completing the static tests, the athlete was instructed to run backwards on the force plate, touching the first and second force plates, respectively. This move was repeated several times for each sample to determine the best option. To obtain good samples, novice athletes typically repeat this movement 15 times. However, for professional athletes, this test produced positive results on average in the first five attempts. Because of the large number of statistical samples, the sampling was initially conducted entirely in the
Description
This study examines the effects of blindfold training on backward running in novice and experienced male handball players.