Postgraduate M. Tashtarian
Professor, Dr.Hab. A.A. Shalmanov
Associate Professor, PhD E.E. Zhigun
Russian State University of Physical Culture, Sport, Youth and Tourism (UWJKBAR), Moscow

Keywords: biomechanism, whip, ankle joint, smash, knee joint, hip joint, shoulder joint, elbow joint, wrist joint, racket center of mass, badminton smash

Introduction. Smash is a complex motor action that includes two key technical components: leg extension biomechanism and “whip” biomechanism. The efficiency of badminton smash technique depends on player’s physical conditions and individual anatomical characteristics of muscles and joints [2]. It is also very important to find a biomechanical basis for etalon smash technique – a model of motion from elite badminton players.

Biomechanisms are convenient tools for constructing sport technique systems. As defined earlier [3,4], biomechanism is a model (or subsystem) of a human musculoskeletal system that provides energy transformation and transition between parts to achieve the motor action goals.

The objective was to study the “whip” biomechanism in badminton smash.

It is generally accepted, that most striking actions, pitches and throws are performed using a “whip” biomechanism. The essence of this biomechanism is consecutive acceleration and deceleration of body parts, proximal to distal. The proximal part of body segment is accelerated towards hitting point by contracted muscles, while distal part remains behind because of inertia. It results in stretching muscles around proximal joint and accumulation of elastic deformation energy. Then these joint torques decelerate proximal part of body segment and elastic deformation forces combined with muscle contraction forces accelerate distal part of body segment. So, the process of consecutive acceleration and deceleration of kinematic chain parts results in acceleration of terminal (striking) segment.

From kinematic point of view the “whip” biomechanism may be considered as a temporal proportion of linear and angular velocity maxima for body parts.

Methods. A laboratory experiment was set in Sports Scientific Research Institute biomechanics laboratory of Russian State University of Physical Culture, Sport, Youth and Tourism (RSUPCSYT). A group of subjects consisted of male badminton players (age 24-32 years, height 1.68-1.82 m, weight 65-91 kg). Raw data was acquired at 200 Hz from 8 high speed cameras “Oqus 3” using “QualisysTrackManager” software. A 3D miltisegmental model of human body was estimated to acquire spatio-temporal characteristics of a smashing arm with a racket.

Subjects performed two tasks (forehand smash and jump smash) followed by a pass from the assistant. The best trials that gained racket center of mass maximum velocity were considered for analysis. The following points were marked to acquire linear and angle characteristics: ankle joint, knee joint, hip joint, shoulder joint, elbow joint, wrist joint, racket center of mass.

Results and discussion. In this study two groups of badminton smash characteristics were taken under consideration: 1) linear velocity maxima for right leg joints, striking arm joints and racket center of mass; 2) time periods between joints linear velocity maxima and racket center of mass velocity maximum (temporal characteristics).

The linear velocity of right leg joints, striking arm joints and racket center of mass increase from 1,36±0,35 m/s to 22,54±3,09 m/s, on average, when a player performs forehand smash (see Table 1).

Table 1. Linear velocity maxima of marked points and temporal characteristics during forehand smash (n=5)

Figure 1. The linear velocity of shoulder, elbow and racket center of mass in badminton forehand smash

The analysis of leg and arm joints velocity maxima time shows different sequence of body parts acceleration in badminton than that common for most striking actions (proximal to distal segment). Elbow linear velocity maximum occurs significantly earlier (0,111±0,022 s) than shoulder maximum (0,086±0,016 s). Differences are significant at p<0,05 (see fig. 1)

The second feature of consecutive acceleration of body parts is that right hip and knee velocity maxima occur almost simultaneously.

In forehand smash the “whip” biomechanism takes place during support period. In that case, besides internal torques, the athlete’s body is impacted by external torques, mostly by ground reaction forces.

In jump smash the athlete’s body is impacted only by internal torques. Therefore, besides utilization of muscle torques and elastic deformation energy of muscles, the acceleration of body parts is realized according to moment of momentum conservation law.

Table 2 shows that linear velocity maxima increase, starting with right hip joint to racket center of mass. It means that the movement of body, hitting arm and racket center of mass is realized according to “whip” biomechanism. The linear velocity maxima mean values for the following joints were calculated: hip - 3,07±0,47 m/s, shoulder - 3,27±3,33 m/s; elbow - 6,63±1,64 m/s; wrist - 9,00±1,20 m/s, racket center of mass - 21,92±2,08 m/s. Similar to forehand smash, elbow velocity maximum during jump smash occurs 0,044 s earlier, on average, than shoulder maximum (p<0,05).

Table 2. Linear velocity maxima of marked points and temporal characteristics during jump smash (n=5)

Counter movement was observed in hips and waist when a player bends his lower extremities. The following sequence of velocity maxima was observed: hip (3,07±0,47 m/s), knee (2,76±0,88 m/s), ankle (4,46±1,12 m/s).

The results of forehand smash and jump smash comparative analysis of linear velocity characteristics reveal significant differences for lower limb joints and for shoulder only. No significant differences found for elbow, wrist and racket center of mass.

Conclusion. The ”whip” biomechanism in badminton smash has particular feature: elbow velocity maximum occurs significantly earlier than shoulder maximum (p<0,05). The time between elbow and shoulder velocity maxima is 0,044 s for forehand smash, on average, and 0,025 for jump smash.

No significant differences observed for racket center of mass linear velocity maxima between forehand smash (22,54±3,09 m/s) and jump smash (21,92±2,08 m/s). Significant differences between velocity maxima were evaluated only for right leg joins and shoulder joint of the hitting arm. That can be explained by different interaction patterns of these body parts during forehand and jump smash.

Referеnces

1. Agashin F.K. Biomekhanika udarnykh dvizheniy (Biomechanics of shot movements). – Moscow: Fizkul'tura i sport. – 1977. – 207 p.
2. Pomytkin V.P. Kniga trenera po badmintonu. Teoriya i praktika (Badminton coach's guide. Theory and practice) / V.P. Pomytkin. – Moscow: Pervaya Obraztsovaya tipografiya, 2012. – 344 p.
3. Shalmanov Al.A. Osnovnye mekhanizmy vzaimodeystviya s oporoy v pryzhkovykh uprazhneniyakh: Metod. rekom. dlya slushateley Vysshey shkoly trenerov, fakul'tetov usovershenstvovaniya i povysheniya kvalifikatsii (basic mechanisms of interaction with support in jumping exercises: Method. recom. for students of Higher School of coaches, advanced traininf faculties) / Al.A. Shalmanov, An.A. Shalmanov. – Moscow, 1990. – 48 p.