The Biceps Brachii Role in the Stabilization of the Cross Punch
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Marco Prenassi et al., IJSMR, 2020 3:13 Research Article IJSMR (2020) 3:13 Internal Journal of Sports Medicine and Rehabilitation (ISSN:2637-5044) The biceps brachii role in the stabilization of the cross punch Marco Prenassi1 , Renato D. Donato2,3 , Simona Mrakic-Sposta4* , Lorenzo Rossi5, Luca Andreoletti3, Alessandra Vezzoli4, and Sara Marceglia6 1UO Neurofisiopatologia, Fondazione IRRCS Ca’Granda Ospedale Maggiore Policlinico, Milan, Italy; 2Heracles Gymnasium SSD s.r.l. Fortitudo ETS, Milan, Italy; 3Dipartimento di Scienze Biomediche per la Salute,Università degli Studi di Milano, Milan, Italy; 4Institute of Clinical Physiology, National Research Council, IFC –CNR, Milan, Italy; 5Newronika s.r.l.;6Dipartimento di Ingegneria e Architettura, Università degli Studi di Trieste, Trieste, Italy ABSTRACT Purpose: starting from an injury background, we assumed that *Correspondence to Author: the biceps brachii’s activations could have an important role in Simona Mrakic-Sposta upper limbs injury. In this work we analyzed whether different Institute of Clinical Physiology, activations of the biceps brachii impact on the power transfer National Research Council, IFC – of the punch and how boxers of different skill levels activate the CNR, Milan, Italy biceps brachii when deliver a punch according to their skill level and efficacy. How to cite this article: Methods: we enrolled, basing on official rankings, 23 skilled Marco Prenassi, Renato D. Donato, (n=6) and unskilled boxers. Subjects were instructed to perform Simona Mrakic-Sposta, Lorenzo three cross punches directed to a fixed elastic target triggered Rossi, Luca Andreoletti, Alessan- by the coach whistling, and were monitored through a surface dra Vezzoli, and Sara Marceglia. electromyography sensor (EMG) on the biceps brachii to The biceps brachii role in the stabi- estimate the muscular activation during the performance, and lization of the cross punch. Internal through an accelerometer placed inside the elastic impact target Journal of Sports Medicine and Re- to estimate the impact energy. We analyzed the oscillatory habilitation, 2020; 3:13. content of the EMG signal in order to assess the muscular activation between skilled and unskilled boxers, and between weak and strong punches. Results: both skilled and unskilled boxers threw strong, medium eSciPub LLC, Houston, TX USA. and weak strikes. Skilled boxers performed better than unskilled Website: https://escipub.com/ boxers (47% vs 25% in the “strong punch” category).The EMG analysis revealed a significant increase of lower and higher frequencies (2-4 Hz and 15-17 Hz) and a decrease on the IJSMR: https://escipub.com/internal-journal-of-sports-medicine-and-rehabilitation/ 1 Marco Prenassi et al., IJSMR, 2020 3:13 medium frequencies (7-9 Hz) in the skilled boxers compared to the unskilled boxers in strong punches. Weak punches had a similar activation patterns in the two groups. Conclusions: our results support the hypothesis that skilled boxers adapt their activation pattern of the biceps to better stabilize the punch delivery (and thus increasing the transfer of force). Keywords: Boxing; Biceps brachii; EMG analysis; Punch; Shoulder injury; Tendon detachment Introduction impact. It is supposed that expert boxers can Boxing discipline is a sport characterized by generate more impact force compared to novice many traumatic phenomena. Indeed, the fighters boxers, and more impact force means an in- have to absorb the impact of the blows, to the creased stress to the throwing arm. head and the body, thrown by the rival but also, These force impacts, generated by the punch they have to absorb the impact of their own when hits the target, stress the upper limb joints. punches. Self-inflicted hand injuries could arise Studies on these impact forces managed to from these latter impacts. demonstrate that, during the impact, the high ac- Many studies investigate direct injuries to the tivation of flexor and extensor muscles, recruited hand and the head caused by the traumatic fist to close the hand, produce a shot with 55% more events. In particular, they focused on concus- strength compared with a shot without clenched sions, in short and long terms [1,2,3] and also on hand. The high muscle activation reduces inju- metacarpal injuries [4,5,6,7]. Not less important, ries, metacarpal joint deformation, and in- however, is the indirect trauma, caused by repet- creased power transfer to the target. [10] The sta- itive training sessions, to the muscles and ten- bilizing muscle action generated by the impact dons. The impact overload can direct the ath- on the target appears to be an involuntary kind, letes to have tendinopathy, muscle tears, and, at where the term “involuntary” is a not reflective worst, tendons detachment. Novice boxers have event in line with the act’s finality. been shown to have fewer shoulder injuries than Exactly as the insights of Eugéne Minkowski experienced boxers; this statistical evidence in ’57 when he described the body muscle com- supports the idea that indirect trauma injuries, pensation to keep the orthostatic position, which caused by functional overload, are no less im- is in a continuous strain by perturbative force. [11] portant than direct trauma injuries. Shoulder in- The body implements continuous compensation, juries etiology by overload training can be identi- without a real consciousness, intrinsically moti- fied in the defective movement of the blow. In- vated, and intentioned, to reach the aim. As de- correct movement patterns can stress the shoul- scribed by Minkowski E. (1957) and Lacquaniti & der and set movement patterns characterized by Maioli (1989), the researches have shown that scapular dyskinesia with an increase of extra-ro- there are many anticipatory muscle activations, tation [8]. Moreover, it can add an inaccurate con- without the perception of consciousness, to sta- trol of scapular muscle and a bad activation of bilize posture and thus be able to initiate con- the serratus anterior that can create a scious action [11,12]. sub-acromial impingement. [9] Not only imperfect An intentional impact, like a blow or a support- skills are dangerous for athletes' structures; a foot under a jump, produces necessarily an in- perfect shot still increases the overload of the voluntary muscle act to avoid unexpected results. IJSMR: https://escipub.com/internal-journal-of-sports-medicine-and-rehabilitation/ 2 Marco Prenassi et al., IJSMR, 2020 3:13 This unconscious activation must be precisely involving the hips, torso, and upper arm, in which tuned to the gesture to be performed. When the weight is transferred from the rear foot up to there isn’t tuning among anticipatory/compensa- the knuckles of the hand [18]. tor muscle activation and finality act, there is the Nakano et al, (2014) [19] suggests that the im- probability of failure of the qualitative gesture or, pulse of the cross punch to the face is more de- in the worst, injuries.We can have a striking ex- pendent on the final pre-impact momentum of ample in the fright and pain experienced during the punching arm rather than the momentum of the loss of the last step when people go down the other body segments, so its extension before the staircase without attention. The fails of antic- the impact is vital in delivering a “strong” punch. ipatory muscle activation obligate the body to In this complex action, the biceps brachii may be compensate for the surprise of the impact force involved in dampening the extension velocity of with the ground with the massive recruit of an- the arm, limiting the impact force of the punch, tigravitational chains and with a possibility of se- or, after the impact; it may contribute to stiffening vere injuries to the back. Recent studies showed the arm and consequentially increasing the en- that the repeated impact force, arise from the ergy transfer. In this work, we also argue that this foot support on the ground, generates electro- stiffening motion could be linked to the inflamma- myographic variances of the muscle activities to tion of the long head of the biceps brachii. decrease soft tissue vibration [13] and the over- To better understand the role of the correct mod- load tendon muscle. [14] This evidence supports ulation of the biceps brachii activation in the the idea that to the increment of the impact there cross punch stabilization, in this study we aim to: is an increase of muscle recruit to reduce the a) assess whether different activations of the bi- overload of the joint and the tendon muscle ceps brachii impact on the power transfer of the structures. punch; b) analyze how boxers of different skill The constant repetition of massive recruitment levels activate the biceps brachii when deliver a and hard force expression, generated from the punch according to their skill and efficacy. To do repetitive specific workout, could be the principal so, we neurophysiologically analyzed the re- cause of upper arm injuries, including long head sponse of the biceps brachii while boxers of dif- brachii biceps muscle [15,16]. It is not infrequent ferent skill levels were executing a cross punch, that boxers report pain shoulder near the proxi- by measuring the activation of this muscle with a mal attachment and, mostly in the heavyweight bipolar superficial electromyogram (EMG) and class, can suffer the laceration or complete de- an accelerometer inside an elastic target to as- tachment of the distal attachment. In the study sess the impact force between punches. conducted by Siewe et al, (2015) on boxing com- Materials and Methods petition, the most frequent injuries, not including Twenty-three boxers were enrolled in this study the injuries to the head, involve the upper limbs. and divided into two groups (skilled-unskilled) [17] For this reason, it’s important creating fo- using the Italian Boxing Federation (FPI, Feder- cused training programs, that can help the power azione Pugilistica Italiana), Association Interna- increase of muscle groups stressed by impact tionale de Boxe Amateurs (AIBA) Open Boxing force, could extend the boxer’s sports career, (AOB) score system [20].