Biomechanics of the Jump Shot Kelvin Wang BIOL438 April 15, 2014
Technique—3 Phases Preparation—balance, center of mass over support Execution—jump and shoot, release Follow Through—landing, balance, center of mass over support Preparation—balance, center of mass over support Execution—jump and shoot, release Follow Through—landing, balance, center of mass over support Source: The Seattle Times Preparation Execution Follow Through
Technique—Muscles Used Hip extension—hamstrings (biceps femoris, semitendinosus, semimembranosus), gluteus maximus Fast-twitch higher vmax, higher power, more efficient at higher velocity Knee flexion/extension— quadriceps muscle eccentrically contracts in preparation, during jump it concentrically contracts Slower-twitch lower vmax, more economical, recruit more motor units Gastrocnemius (fast-twitch) plays role Source: www.oxford174.com
Technique—Muscles Used Shoulder upward rotation— middle and lower trapezius muscles, rhomboids, deltoids Elbow flexion/extension— eccentric contraction of triceps, then concentric to generate force Fast-twitch fibers for greater power Wrist extension/flexion—add spin, velocity to ball Fast-twitch fibers Source: www.rci.rutgers.edu Source: www.endoszkop.com
3 Shots Source: www.lakernation.com Source: ESPN Source: wikiHow
LoggerPro Analysis
Normal Jump Shot—Momentum Before release, triceps extension (assume zero initial momentum): a = ∆v/∆t = 51.39 m/s2 (from LoggerPro) F = ma = (0.62 kg)(51.39 m/s2) = 31.86 N ∆t = 0.096 s, so: J = F∆t = 3.06 kg-m/s At release: vx,ball = 4.40 m/s vy,ball = 5.68 m/s Total velocity = 7.18 m/s Assume mball = 0.62 kg, then: p = mv = (0.62 kg)(7.18 m/s) = 4.45 kg-m/s Thus, the triceps extension motion for shooting the ball imparts 3.06 kg-m/s impulse to the ball from preparation phase to release. Wrist flick motion gives ball extra velocity and could account for the difference in impulsemomentum.
Normal Jump Shot—Work and Energy Kinetic energy = 0.5mv2 At release: KE = 0.5(0.62 kg)(7.18 m/s) 2 = 15.99 J Work = ∆Energy = 15.99 J (assume E0 = 0) From the start of triceps extension to release: Power = Work/∆t = 15.99 J/0.096 s = 166.6 W
Pull-up Jump Shot—Momentum Before release, triceps extension (assume zero initial momentum): a = ∆v/∆t = 139.9 m/s2 (from LoggerPro) F = ma = (0.62 kg)(139.9 m/s2) = 86.74 N ∆t = 0.04 s, so: J = F∆t = 3.47 kg-m/s At release: vx,ball = 4.70 m/s vy,ball = 6.24 m/s Total velocity = 7.81 m/s Assume mball = 0.62 kg, then: p = mv = (0.62 kg)(7.81 m/s) = 4.84 kg-m/s Thus, the triceps extension motion for shooting the ball is quicker, and imparts 3.47 kg-m/s impulse to the ball from preparation phase to release. Wrist flick motion gives ball extra velocity.
Pull-up Jump Shot—Work and Energy Kinetic energy = 0.5mv2 At release: KE = 0.5(0.62 kg)(7.81 m/s) 2 = 18.91 J Work = ∆Energy = 18.91 J (assume E0 = 0) From the start of triceps extension to release: Power = Work/∆t = 18.91 J/0.04 s = 472.75 W
Fadeaway Jump Shot—Momentum Before release, triceps extension (assume zero initial momentum): a = ∆v/∆t = 83.2 m/s2 (from LoggerPro) F = ma = (0.62 kg)(83.2 m/s2) = 51.58 N ∆t = 0.08 s, so: J = F∆t = 4.13 kg-m/s At release: vx,ball = 3.88 m/s vy,ball = 7.02 m/s Total velocity = 8.02 m/s Assume mball = 0.62 kg, then: p = mv = (0.62 kg)(8.02 m/s) = 4.97 kg-m/s Thus, the impulse from triceps extension is similar to a normal jump shot, and imparts 4.13 kg-m/s impulse (more than normal or pull-up) to the ball from preparation phase to release.
Fadeaway Jump Shot—Work and Energy Kinetic energy = 0.5mv2 At release: KE = 0.5(0.62 kg)(8.02 m/s) 2 = 19.94 J Work = ∆Energy = 19.94 J (assume E0 = 0) From the start of triceps extension to release: Power = Work/∆t = 19.94 J/0.08 s = 249.25 W
Fadeaway jump shot gives more impulse to shot from triceps extension Normal Pull-up Fadeaway Impulse 3.05 kg-m/s 3.46 kg-m/s 4.17 kg-m/s Momentum 4.34 kg-m/s 4.85 kg-m/s 4.96 kg-m/s Force 31.6 N 89.2 N 52.6 N Energy 16.03 J 19.31 J 19.83 J Power 159.6 W 471.8 W 273.4 W Fadeaway jump shot gives more impulse to shot from triceps extension Higher proportion of momentum is from triceps, less from wrist flick
Pull-up jump shot results in more force in shooting the ball Normal Pull-up Fadeaway Impulse 3.05 kg-m/s 3.46 kg-m/s 4.17 kg-m/s Momentum 4.34 kg-m/s 4.85 kg-m/s 4.96 kg-m/s Force 31.6 N 89.2 N 52.6 N Energy 16.03 J 19.31 J 19.83 J Power 159.6 W 471.8 W 273.4 W Pull-up jump shot results in more force in shooting the ball Running start could have effect
Normal jump-shot results in least kinetic energy to the ball Pull-up Fadeaway Impulse 3.05 kg-m/s 3.46 kg-m/s 4.17 kg-m/s Momentum 4.34 kg-m/s 4.85 kg-m/s 4.96 kg-m/s Force 31.6 N 89.2 N 52.6 N Energy 16.03 J 19.31 J 19.83 J Power 159.6 W 471.8 W 273.4 W Normal jump-shot results in least kinetic energy to the ball Pull-up: running start helps transfer momentumhigher velocity at releasehigher kinetic energy Fadeaway: adjusting for defendershoot ball faster vertically
Pull-up jump shot results in most power Normal Pull-up Fadeaway Impulse 3.05 kg-m/s 3.46 kg-m/s 4.17 kg-m/s Momentum 4.34 kg-m/s 4.85 kg-m/s 4.96 kg-m/s Force 31.6 N 89.2 N 52.6 N Energy 16.03 J 19.31 J 19.83 J Power 159.6 W 471.8 W 273.4 W Pull-up jump shot results in most power greater energy (increase W) and shorter release time (decrease ∆t)
Conclusions Fadeaway jump shot: more triceps used, faster twitch muscles to generate greater impulse Efficient and economical, but difficult to execute Pull-up jump shot: greater force and greater power on shot, due to running start However, relies on running startsudden stop and jump. Slower twitch muscles in leg are less economical at higher contraction speedsfatigue Normal jump shot: least energy, force, and power produced, but not as tiring
References Alexander, M. (1990). The application of biomechanics to basketball skills. CAHPER Journal, 56(3), 4-10. Haefner, J. (2008). Proper Basketball Shooting Technique, Fundamentals, and Form. Retrieved from http://www.breakthroughbasketball.com/fundamentals/shooting- technique.html Okazaki, V. H. A., & Rodacki, A. L. F. (2012). Increased distance of shooting on basketball jump shot. Journal of Sports Science and Medicine, 11, 231-237 Valente, R. (2010). Movement Phase. Jump Shot. Retrieved from http://valentejumpshot.blogspot.com/20 10/10/movement- phase.html Quist, J., VanNostrand, Z., Burns, B. (2012). Science of the 3-Point Shot. Biomechanics of a 3-Point Shot. Retrieved from https://sites.google.com/site/biomechanicszjb/science-of-the-3