Is Wheelchair Basketball a Symmetric or Asymmetric Sport?

Giacomo Farì ^{1,2, *}, Enrica Chiaia Noya ², Laura Dell’Anna ², Vincenzo Ricci ³, Francesco Quarta ⁴, Laura Masiero ⁵, Andrea Bernetti ¹, Marisa Megna ², Maurizio Ranieri ²

1. Department of Experimental Medicine (Di.Me.S), University of Salento, 73100 Lecce, Italy

2. Department of Translational Biomedicine and Neuroscience (DiBraiN), Aldo Moro University, Bari, Italy

3. Physical and Rehabilitation Medicine Unit, Luigi Sacco University Hospital, ASST Fatebenefratelli-Sacco, Milan, Italy

4. Department of Biological and Environmental Science and Technologies (Di.S.Te.B.A.), University of Salento, Lecce, Italy

5. Department of Statistical Science, University of Padova, Padova, Italy

* Correspondence: Giacomo Farì

Academic Editor: Virginia Barone

Special Issue: The New Frontiers of Neurological Rehabilitation: Sport, New Technologies and Advancements in Traditional Therapies

Received: January 16, 2024 | Accepted: June 18, 2024 | Published: June 25, 2024

OBM Neurobiology 2024, Volume 8, Issue 2, doi:10.21926/obm.neurobiol.2402227

Recommended citation: Farì G, Chiaia Noya E, Dell’Anna L, Ricci V, Quarta F, Masiero L, Bernetti A, Megna M, Ranieri M. Is Wheelchair Basketball a Symmetric or Asymmetric Sport? OBM Neurobiology 2024; 8(2): 227; doi:10.21926/obm.neurobiol.2402227.

© 2024 by the authors. This is an open access article distributed under the conditions of the Creative Commons by Attribution License, which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is correctly cited.

1. Introduction

Wheelchair basketball (WB) is an increasingly popular sport. Over the last decade, Paralympic sports, particularly WB, have steadily gained interest [1,2]. Born in the USA at the end of the 40s as a rehabilitation activity for veterans of the Second World War [3], WB today represents an excellent opportunity for physical activity, rehabilitation, and integration for people with disabilities [4]. Fundamental to increasing motor skills, WB also improves the emotional state of people who practice it [5]. Moreover, this sport is an excellent occasion for social inclusion and integration since one of its distinctive features is that athletes and amateurs with different disabilities share the playing court thanks to the classification system that assigns each player a score from 1 to 4.5 based on residual functional abilities and trunk stability [6]. In literature, upper limb muscle strength and aerobic and anaerobic capacity play a significant role in athletic performance among WB athletes with different classification scores [7].

Moreover, shoulder pain in WB players is an important topic [8], as it is an ongoing problem when it comes to injuries related to this sport [9]. It is so relevant that Yildirim et al. proposed a rating scale specifically dedicated to shoulder pain assessment in these athletes [10] and also attempted to investigate the connection between shoulder pain and trunk control in this activity [11]. Ultimately, Wilroy et al. created a 6-week intervention program to enhance sports performance and reduce the risk factors that increase susceptibility to pain or shoulder injury [12].

Considering the necessity to move in a wheelchair, in WB, the concept of symmetry of the sporting gesture revolves around the trunk and shoulders, which are also the anatomical districts most affected by sport-related overuse injuries [9]. In fact, during a WB match or training session, shoulders are constantly overloaded due to the need to move quickly, change direction, pass, and throw the ball. The most involved muscles during these gestures are supraspinatus and biceps brachii [13]. The supraspinatus is an abduction starter, while the biceps guarantee the flexion and supination of the forearm. Thus, it is intuitive that these movements are fundamental in the practice of a wheelchair sport and specifically in WB, which is one of the most demanding sports in terms of wheelchair mobility performance compared to other sports such as wheelchair tennis and wheelchair rugby [14]. To better understand the role carried out by these muscles, a deeper explanation of wheelchair propulsion is needed. The propulsion cycle is made up of two phases: the push phase, also called the force production phase, when hands and rims are in contact, and the recovery phase, also called the non-propulsive phase, when the hands and rims are not in contact each other [15]. The push phase synergy is primarily influenced by muscles engaged in external rotation, shoulder flexion, and scapular protraction. The recovery phase is mainly dominated by muscles involving extension, abduction, internal rotation, and scapular retraction. According to a previous study conducted to analyze muscle activity during wheelchair propulsion using EMG, supraspinatus displayed a high peak activity during the push phase. However, its activity is relevant in both phases. Supraspinatus is involved in external rotation during the push phase and abduction during the recovery phase. As previously declared, another critical muscle involved in wheelchair propulsion is the biceps, activated in the late recovery phase and reaching its peak activity during the last part of the backswing. Moreover, the biceps continue activity until the hand reaches the top dead center on the handrail [16].

Despite the interest in WB in scientific literature increasing in the last few years, the topic of symmetry or asymmetry is still studied exclusively among able-bodied basketball players [17,18]. In WB, symmetry represents a recent and underexplored topic that only a few studies have considered. According to Maloney, sports can be categorized into different groups, with bilateral sports further divided into symmetric or asymmetric sports based on sporting asymmetries, defined as bilateral differences in specific sport-related parameters [19]. Regarding WB, Ferro et al. found asymmetry in wrist peak acceleration during a 20 m sprint test using inertial measurement systems, and this result was not associated with the classification score [20]. Another research aimed to evaluate the interlimb asymmetry of forces developed during an upper limb Wingate aerobic test in a WB player population, finding that forces were asymmetric for most participants [21].

Although these studies provided valuable contributions, there is still a lack of knowledge on this topic, an essential field of interest that could give new perspectives for training and prevention strategies.

2. Materials and Methods

This study aims to investigate whether WB is a symmetrical or asymmetrical sport and, more specifically, to analyze the activity of the shoulder muscles during specific field tests to examine if muscle engagement develops in bilateral differences.

An observational cross-sectional study was carried out.

Ten professional athletes were enrolled in the study. They all belonged to an Italian team competing in the second championship of the Italian Wheelchair Basketball Federation (FIPIC). The tests were conducted during the competitive phase of the same championship when the total training volume ranged from six to eight hours per week. All these players had been practicing WB at a competitive level for at least two years.

Each athlete was asked to read and sign the informed consent containing all the information and objectives of the study. Demographic data, somatic structures’ information (sex, age, height, weight, dominant upper limb), and medical diagnosis for motor impairment were collected. The athletes were homogeneous in terms of disability since they all suffered from paraparesis and predominantly used wheelchairs in daily life activities. None of them had suffered recent injuries or had current musculoskeletal diseases.

To assess muscular activation, a surface electromyograph (mDurance^®-mDurance Solutions SL, Granada, Spain) was simultaneously used to record and analyze the supraspinatus and biceps brachii muscles activation measured as Root Mean Square (RMS) expressed in microvolts [22,23]. Two-channel bipolar sensors for recording the superficial muscle activity were positioned on the proximal 2/3 of the supraspinatus muscle and the distal third of the brachial biceps bilaterally [24].

All participants performed three field tests taken from a field battery of tests considered valid and reliable for WB players [25]. The three tests considered for this assessment, which were already used in previous studies [26], were taken to consider sport-specific gestures of WB, such as speed, wheelchair maneuverability, and wheelchair ball handling. Specifically, the field battery was conducted as follows:

Sprint test: this test consists of a 20-meter sprint in a straight line to evaluate speed. At the starting signal, the athlete sprints, covering a distance of 20 meters in a straight line in the shortest time possible. Two attempts were made, and only the best one was recorded.

Figure 8 test without the ball: this test evaluates the maneuverability of the wheelchair. At the starting signal, the athlete moves between two cones, located 5 meters from each other and equidistant from the halfway line, drawing a figure 8. The number of laps completed in 1 minute was recorded (rpm).

Figure 8 test with the ball: this test evaluates wheelchair maneuverability and WB motor skills. At the starting signal, the athlete moves between the same cones as above, drawing a figure 8 and handling the ball according to the current rules of the International Wheelchair Basketball Federation. The number of laps completed in 1 minute is recorded (rpm).

The tests were explained to the athletes before execution, ensuring each player warmed up for 5 minutes before each test and rested for 5 minutes immediately after. All the WB players were asked to wear the straps to make the test execution safe and homogeneous.

Ethical approval was granted by the Institutional Review Board of the Department of Biological and Environmental Sciences and Technologies of the University of Salento (approval number 2/2023). The principles of the Declaration of Helsinki performed all the procedures. Each athlete was asked to read and sign the informed consent containing all the information and objectives of the study.

2.1 Statistical Analysis

Data were analyzed with RStudio, a free statistical software environment for statistical computing and graphics.

Univariate linear regressions were used to appraise confounders, but none were found. The τ test (Tau test), a non-parametric hypothesis test for statistical dependence based on the τ coefficient (Kendall's τ), was used to assess a possible association between the variables. It is a particular case of a more general correlation coefficient, given that it does not rely on assumptions about the evaluated variables' distributions. This study chose the τ test because of the non-normality of the variables' distributions. Under the null hypothesis of independence between two variables, the sampling distribution of τ has an expected value of zero. The null hypothesis of the absence of correlation cannot be accepted when the p-value associated with τ is <0.05.

3. Results

Ten athletes were enrolled in the study, whose demographic characteristics are summarized in Table 1.

Table 1 Demographic characteristics of the sample.

In all three tests, a statistically significant positive correlation was found (p-value < 0.05) in the comparison between the RMS of the right supraspinatus and the RMS of the left supraspinatus. As the right supraspinatus RMS increases, the left supraspinatus RMS (p-value 0.004 for sprint test; p-value 0.016 for figure 8 test without ball 2; p-value 0.009 for figure 8 test with ball). All the RMS scores are expressed in microvolts. These findings are graphically described in Figure 1.

Figure 1 Comparison between left and right supraspinatus RMS in the three tests (RMS is expressed in microvolts).

The same comparison was repeated for the right and left biceps brachii muscles but, in this case, the correlation was weakly positive or negative, therefore not statistically significant (p-value 0.155 for sprint test; p-value 0.291 for figure 8 test without ball, p-value 0.9 for figure 8 test with ball).

Then, a comparison between the right and left supraspinatus RMS and the right and left biceps brachii RMS and the performance of the athletes in the three tests was performed.

There is a negative correlation between the right biceps brachii RMS and the performance in the figure 8 test without the ball and between the right and left supraspinatus RMS and the performance in the figure 8 test with the ball; therefore, when the muscle activation increases the related performance decreases. These findings are graphically described in Figure 2.

Figure 2 Comparison between right and left supraspinatus RMS (microvolts) and performance and between right biceps brachii RMS (microvolts) and performance in WB tests - significant correlations.

No further correlations were highlighted between the RMS of these muscles and the athletes’ performance in the remaining evaluations. No statistically significant association emerged between the symmetry index of the supraspinatus and biceps brachii muscles and the performance in the three tests mentioned above.

4. Discussion

These results show that a more significant asymmetry in shoulder muscle recruitment guarantees a better WB-specific gesture and, therefore, a more effective performance. Thus, a training program focused on improving the refinement and technical precision of the athletic gesture may be the key to enhancing athletic WB players’ performance.

An object showing exact correspondence between its left and right sides is defined as symmetrical [27]. Although to our eyes, the human body may appear symmetrical about a vertical axis because we have two arms, two legs, two eyes, and so on, in reality, it is not. Humans naturally prefer one side of their body when asked to perform a motor task [28,29] and maintain an asymmetric posture for a long time, which can influence phenotypic plasticity [30]. Therefore, asymmetry appears part of human nature, behavior, and sporting activities [31,32].

Practicing a sport is a highly complex activity that requires excellent physical ability and is sometimes characterized by asymmetric muscle activation, which is functional to better athletic sport-specific performance.

Many sports are characterized by rapid sequences of asymmetric gestures that combine strength and motor refinement, such as in football or golf, which are considered intrinsically asymmetric [33,34]. However, WB has never been defined as a symmetrical or asymmetrical sport. It is unknown whether training athletes as if it were symmetrical or not to improve sport-specific performances is more beneficial.

From the analysis of the collected data, it emerged that, both in the sprint and figure 8 tests with and without the ball, the RMS of the right supraspinatus and that of the left one increase together, so the muscle activation seems symmetrical. However, the exact correspondence was not found in the muscular recruitment of the biceps brachii, so it would seem that the muscular activation of the two biceps is not symmetrical.

The difference between the muscle recruitment of the supraspinatus and the biceps could be justified because the supraspinatus is involved in load work, while the biceps are in precision and technical gesture activities. Consequently, the biceps are called to adapt, second by second and in a different way for each side, to perform fine movements [35]. Myers et al. demonstrated that biceps are muscles involved in rapid and precise athletic gestures [36]. Particularly concerning WB, athletes are called to activate the upper limbs differently than able-bodied athletes in carrying out specific gestures such as ball shooting [37]. The need to maintain a functional movement of all the joints of the upper limb despite motor limitations means that the fulcrum of the refined movement is not the shoulder alone but the shoulder-elbow complex, which, therefore, requires a more significant and delicate involvement of the biceps.

On the contrary, in wheelchair sports and the daily living of wheelchair users, the supraspinatus muscles are essential for strength activities, such as the movement of propulsion, since they guarantee the start of abduction and external rotation movements and allow control the shoulder range of motion (ROM) [38]. These muscles play an essential role in shoulder joint stability. Consequently, they are the first target in the rehabilitation protocols dedicated to WB players when they suffer from shoulder pain, primarily aiming to improve shoulder ROM and increase strength in activities such as linear sprinting [39].

In particular, the negative correlation between the right biceps brachii RMS and the performance in figure 8 test without ball and between the right and left supraspinatus RMS and the performance in figure 8 test with ball demonstrates that when an athlete is asked to perform a complex and sport-specific gesture, such as in figure 8 tests, shoulder muscles recruitment will be reduced compared to explosive strength tests, such as the sprint test. This further supports the hypothesis that technical gestures in WB require refined and precise movements to the detriment of strength. For this same reason, we consider the absence of correlation between SI of the supraspinatus and biceps brachii muscles and performance in the three exercises. All these findings demonstrate that a symmetrical activation of the shoulder muscles could not influence performance in WB athletes, like in other sports. Haugen et al. investigated possible associations between kinematic asymmetry and injury prevalence. They did not find any correlation [40] with the paper of Exell et al., which stated that strength imbalances are joint and task-specific [41]. Upon a more critical reading of these findings, however, it seems more correct to assume that an increased and symmetrical shoulder muscle recruitment does not translate into a better gesture in WB, which is a sport that requires extreme agility and specific muscle activation, that must change from side to side in every moment of the game. During a match, in a few seconds, a player can be called upon to receive and pass the ball, move quickly in a short space, and attempt to shoot with the greatest possible precision. So, these activities require a remarkable ability to work asymmetrically with the upper limbs and are more frequent than strength activities, which are also essential but less recurring.

So, the question we asked in the title was only intended to spur the curiosity of researchers in the field, and clearly, it is not easy to give a final answer. Nevertheless, our findings may be engaging in promoting new attention to asymmetric training for WB athletes’ upper limbs to improve technique. Traditional training and rehabilitation protocols for WB players are based on shoulder symmetrical exercises that aim at enhancing strength without particular attention to the fluidity and agility of the gesture [12,42]. On the contrary, future protocols should be more personalized and selective in muscle training while also taking advantage of increasingly precise detection tools such as inertial sensors [43] and surface electromyographs [39].

The need to improve an athlete's sporting performance is common to all sports, in which training must simultaneously increase performance and reduce the risk of injury [44,45]. This necessity is even more significant in WB since players are persons with disability and often daily wheelchair users. For them, this sport is primarily an opportunity for rehabilitation. Therefore, training sessions must be aimed at improving performance without running the risk of overloading the musculoskeletal system with symmetrical workloads in the gym, which could be harmful and not very useful and involve unnecessary energy disposal. In fact, by perfecting their movements, athletes can minimize inefficiencies and make their sporting actions more advantageous and practical, enhancing their performance. Knowing the importance of the asymmetry of shoulder muscle activation and making technique prevail over strength could guide future training protocols for WB, as for other wheelchair sports with similar performance demands. This study has some limitations. First, the small sample size is because WB competitive athletes are few and are often busy with sports competitions, so involving them in scientific research isn't easy.

Moreover, the symmetry index and the RMS of only two shoulder muscles were investigated, while WB gestures involve many upper limbs and trunk muscles. This choice was made because supraspinatus and biceps are the most important in WB gestures, according to the available literature [46,47,48]. Finally, we did not distinguish the athletes concerning their essential medical diagnosis. Still, in this specific sample, it was not significant since the disabling outcome of these pathologies was the same for all players, i.e., paraplegia. Consequently, the motor disability was the same for all athletes.

5. Conclusions

Greater and symmetrical muscle recruitment does not translate into a better WB performance. On the contrary, an asymmetrical, rapid, and precise activation of the muscle involved in sport-specific gestures seems more valuable and functional for WB performance. WB is a complex sport in which technical skills may be more important than muscular strength and often imposes asymmetric gestures.

Further studies are necessary to delve into these results, which are still preliminary, aiming for increasingly effective and safe training programs for WB players.

Acknowledgments

The authors would like to thank the Italian Wheelchair Basketball Federation (FIPIC) for the support in the athletes’ enrollment in this study.

Author Contributions

GF: contributed to conception, design of the study, data collection and analysis, and wrote the draft of the manuscript. ECN and LDA: contributed to conception, data collection and design of the study. AB and VR: contributed to manuscript revision. MR and MM: supervised the study. LM: contributed to data analysis. All authors discussed the results and contributed to the final manuscript.

Funding

The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.

Competing Interests

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Data Availability Statement

The datasets used and analysed during the current study will be made available upon reasonable request to the corresponding author, G.F. giacomo.fari@unisalento.it