Biomechanics of the Jump Shot Kelvin Wang BIOL438 April 15 2014 Technique3 Phases Preparationbalance center of mass over support Executionjump and shoot release Follow Throughlanding balance center of mass over support ID: 771506
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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 Execution Follow Through Source: The Seattle Times Preparation—balance, center of mass over support Execution—jump and shoot, release Follow Through—landing, balance, center of mass over support
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 contractsSlower-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 ballFast-twitch fibers Source: www.endoszkop.com Source: www.rci.rutgers.edu
3 Shots Source: www.lakernation.com Source: wikiHow Source: ESPN
LoggerPro Analysis
Normal Jump Shot—Momentum Before release, triceps extension (assume zero initial momentum): a = ∆v/∆t = 51.39 m/s 2 (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 v y,ball = 5.68 m/sTotal velocity = 7.18 m/sAssume mball = 0.62 kg, then: p = mv = (0.62 kg)(7.18 m/s) = 4.45 kg-m/sThus, 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 = 0.5mv 2 At release: KE = 0.5(0.62 kg)(7.18 m/s) 2 = 15.99 JWork = ∆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/s 2 (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 v y,ball = 6.24 m/sTotal velocity = 7.81 m/sAssume mball = 0.62 kg, then: p = mv = (0.62 kg)(7.81 m/s) = 4.84 kg-m/sThus, 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 = 0.5mv 2 At release: KE = 0.5(0.62 kg)(7.81 m/s) 2 = 18.91 JWork = ∆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/s 2 (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/sTotal velocity = 8.02 m/sAssume m ball = 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 = 0.5mv 2 At release: KE = 0.5(0.62 kg)(8.02 m/s) 2 = 19.94 JWork = ∆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
Normal Pull-up Fadeaway Impulse 3.05 kg-m/s 3.46 kg-m/s4.17 kg-m/sMomentum 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
Normal Pull-up Fadeaway Impulse 3.05 kg-m/s 3.46 kg-m/s4.17 kg-m/s Momentum4.34 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 Pull-up Fadeaway Impulse 3.05 kg-m/s 3.46 kg-m/s4.17 kg-m/s Momentum4.34 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 momentum higher velocity at releasehigher kinetic energy Fadeaway : adjusting for defender shoot ball faster vertically
Normal Pull-up Fadeaway Impulse 3.05 kg-m/s 3.46 kg-m/s4.17 kg-m/s Momentum4.34 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 executePull-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.htmlOkazaki, V. H. A., & Rodacki, A. L. F. (2012). Increased distance of shooting on basketball jump shot. Journal of Sports Science and Medicine, 11, 231-237Valente, R. (2010). Movement Phase. Jump Shot. Retrieved from http:// valentejumpshot.blogspot.com/20 10/10/movement-phase.htmlQuist, 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