Journal of Human Kinetics volume 42/2014, 73‐79 DOI: 10.2478/hukin‐2014‐0062 73 Section I – Kinesiology Biomechanical Analysis of the Jump Shot in Basketball by Artur Struzik1, Bogdan Pietraszewski1, Jerzy Zawadzki1 Basketball players usually score points during the game using the jump shot. For this reason, the jump shot is considered to be the most important element of technique in basketball and requires a high level of performance. The aim of this study was to compare the biomechanical characteristics of the lower limbs during a jump shot without the ball and a countermovement jump without an arm swing. The differences between variables provide information about the potential that an athlete can utilise during a game when performing a jump shot. The study was conducted among 20 second‐league basketball players by means of a Kistler force plate and the BTS SMART system for motion analysis. The variables measured included the take‐off time, mean power, peak power, relative mean power, jump height, maximum landing force and calculated impact ratio. Surprisingly, more advantageous variables were found for the jump shot. This finding suggests a very high performance level in the jump shot in the studied group and a maximum utilisation of their motor abilities. Both types of jumps were characterised by high mean and peak power values and average heights. The high forces at landing, which result in considerable impact ratios, may have prompted the studied group to land softly. Use of the countermovement jump without an arm swing is recommended to assess and predict the progression of player’s jumping ability. Key words: basketball, jump shot, countermovement jump, power, soft landing. Introduction The main objective of each basketball Bartlett, 1996). When a player is covered by an player during a game is to score points. In an aggressive defender, his aim is to perform the attempt to do so, an athlete might perform a jump shot at the highest possible release point. shot, set shot, layup or a free throw. As the Additionally, the shot must reach that release discipline has evolved and more athletic players point in the shortest time frame. These factors have practised this sport discipline, defence has result in an extension of the body in players become increasingly efficient. As a result, the two‐ performing the jump shot (Rojas et al., 2000). legged jump shot has become more frequent, Previous biomechanical studies on shots amounting to over 70% of all the shots during a performed by basketball players have typically game, which necessitates a greater performance measured kinematic variables, such as maximum level for athletes executing the jump shot to angular values and angular velocities in players’ increase the height at which the ball is released individual joints (McClay et al., 1994a), temporal (i.e., the release point) (Oudejans et al., 2012). This profiles of changes in the angular values of movement must be automated so that, regardless individual joints and angular velocities (Kornecki of the external factors, the player achieves and Lenart, 1997), the release angle and velocity maximum repeatability (Kornecki et al., 2002). of the ball, changes in the location and velocity of The factors that affect the height at which a shot is the centre of mass, the rotation of the upper body performed include the shooter body height, jump of a shooter (Miller and Bartlett, 1996), the effect height and arrangement of body parts (Miller and of initial ball rotation (Tran and Silverberg, 2008) 1 ‐ Department of Biomechanics, University School of Physical Education, Wrocław, Poland. Authors submitted their contribution of the article to the editorial board. Accepted for printing in Journal of Human Kinetics vol. 42/2014 on September 2014. 74 Biomechanical analysis of the jump shot in basketball and the foot position when shooting (Spina et al., player is the power generated by the lower limbs, 1996). Therefore, the focus of prior studies was on as the game of basketball is based on explosive the shooting technique rather than the motor movements, such as accelerations, quick cuts and abilities of the shooter. In‐depth analyses of the jumps. free throw have also been conducted (Tran and The arm swing executed prior to take‐off Silverberg, 2008). helps reach greater jump heights in the An analysis of the ground reaction forces countermovement jump (CMJ) (Hara et al., 2006). generated by basketball players during a shot However, when performing a jump shot, provides information concerning the phases of basketball players use their upper limbs in ways take‐off and landing (McClay et al., 1994b), which that do not necessarily enhance their jumping permits the studies to focus on not only the performance, i.e., motions other than arm swings. jumping performance (i.e., the jump height and Additionally, it is not known whether this upper time to reach this height, indirectly represented by limb movement is a factor that affects the the power of the lower limbs), which is of key utilisation of maximum abilities of the lower importance to the shot, but also on the health‐ limbs during a jump. A classical measure of oriented aspects of this movement. Learning a soft maximum speed‐strength abilities of lower limbs landing technique is essential for basketball when performing a vertical jump is the CMJ players, despite the use of well‐cushioned without an arm swing. Therefore, the lower limb footwear (Brizuela et al., 1997). Hard landing power and the jump height will be smaller in the causes an excessive load on the lower limbs jump shot. Thus, the aim of the present study was (which may potentially exceed the body weight to compare biomechanical characteristics of lower by several times), which in effect can lead to local limbs (in take‐off and landing phases) achieved by overload and injuries. Therefore, it is important a basketball player when performing a jump shot that a player absorbs the shock (by flexing his and the maximum CMJ achieved without an arm lower limbs during landing) and does not land on swing. The potential differences between these extended legs. An earlier contact of the heel with two movements are likely to provide information the ground increases the impact force, which is about the additional potential a player might why midfoot landing is preferred over landing utilise during a game when performing a jump with the whole foot (DeVita and Skelly, 1992; shot. Can a player achieve similar values of lower Bober et al., 2002). limb variables in the jump shot and in the CMJ The shooting techniques of different without an arm swing? If so, that player would basketball players seem similar, although the demonstrate the ability to perform one of the most differences are sufficiently significant to the point important technical elements of basketball. that each player can be considered to have a unique shooting style. This observed Material and Methods phenomenon is due to different length The study was conducted among 20 well‐ proportions between upper body segments trained junior division II basketball players. The (Kornecki et al., 2002). Furthermore, a shooting study group was characterised by the following technique (often resulting from a particularity of mean properties (±SD): body height – 193.1 ± 7.9 external factors, e.g., situation shots) is typically cm, body mass – 84.8 ± 9.8 kg, age – 18.4 ± 1.3 justified by its accuracy. Therefore, it is more years. In all measurements, the subjects wore reasonable to place emphasis on variables professional basketball footwear typically used responsible for the release height than on the during training and competition. The tests were minute technical nuances of the shot. Training performed in a Biomechanical Laboratory. Prior to that focuses on maximising the release height will the tests, the participants were familiarised with allow for coping with a defender and performing the purpose of the study. Additionally, each a shot from a more convenient position. A high participant provided their written consent for level of performance in a jump shot forces players participation in the experiment. The research to utilise their maximum jumping (i.e., speed‐ project was approved by the Senate’s Research strength) and coordination abilities. A motor Bioethics Commission at the University School of ability particularly important to a basketball Physical Education in Wrocław, Poland. Journal of Human Kinetics ‐ volume 42/2014 http://www.johk.pl by Struzik A. et al. 75 To measure ground reaction forces, one Kistler time, and g is the acceleration due to gravity. force plate (model: 9286A; Winterthur, The jump height (hs) was calculated based on Switzerland) with BioWare® software was used the time of the flight phase (tl): for each leg. Displacements of the upper level of . the lower limbs were measured with the BTS The impact ratio (IR) is the quotient of SMART system (BTS Bioengineering, Milan, Italy) maximum values of ground reaction forces during using passive markers that reflect the emitted landing (Fl) and take‐off (Fo) phases: infrared radiation (IR). The markers were located at the greater femoral trochanters on both sides of . the body. The system used 6 cameras to capture at To analyse the differences between individual a frame rate of 120 Hz and 0.2 mm resolution. To variables, the authors used a t‐test to determine synchronise the measurements, the sampling the significance of differences for dependent frequency of the platforms was set at 240 Hz. The variables due to the normality of the distribution BTS‐SMART Analyzer software was used to of the variables. The level of significance was set facilitate the synchronisation of the recorded data. at α = 0.05. Prior to the examination, each subject warmed up for 10 minutes.