The step back has been popularized in the recent decade by some of the best basketball players in the world, namely, Steph Curry, James Harden and Kemba Walker. The step back revolves around a sudden change in direction to clear space away from the defensive player for a shot. The kinematics of a change of direction maneuver shown in this particular picture involves a unilateral (Curry’s right leg) support with the ankle in either a neutral or slightly dorsiflexed position (depending on his initial force applied before the change of direction occurs), and the knee and hip in a flexed position. Understanding the kinematics of this move allows professionals to make educational assumptions on possible stresses on the joints (ankle, knee, hip, lumbar spine). For example, ACL stress has been shown to increase with a lower knee flexion angle below 30 degrees due to the increase anterior shear force on the knee from patellar tendon (Utturkar et al., 2013); lateral foot plant position has also been encouraged to maximize braking force (Dos’Santos et al., 2018); both of which are considered as kinematic concepts.
With regards to changing directions, an initial deceleration is required, this means that Curry will have to produce a force eccentrically through his quadriceps and tricep surae, followed by a isometric rate of force development in the same musculatures in order to oppose the initial velocity in the direction towards the basket. Following the successful stoppage, he will then require to initiate a concentric force around 180 degrees away from his initially planned direction, which will dictate his acceleration towards the newly desired position away from the defender. All of which requires sound foot placement, knee flexion angle, body lean posture, and trunk stability in order to achieve (Falch et al., 2019). The forces that are required can be tremendous, and without sound tissue quality, the body can take on large amounts of stress, risking injury. For instance, eccentric hamstring capacity largely dictates braking ability during change of direction tasks, and concentric hamstring capacity dictates the acceleration phase of a change of direction maneuver (Falch et al., 2019). Since change of direction encompasses a change between eccentric to concentric, reactive strength ability such as tendon health and capacity can also contribute kinetically. Plyometric training and linear sprint can both contribute to velocity-based change of direction and also rate of force development ability (Falch et al., 2019).
Overall, the picture demonstrates a typical basketball step back, and Stephen Curry seems to perform it with sound kinematics and although we cannot speak on the exact kinetic readings, the maneuver itself allows us to theorize the possible forces he is required to overcome and project.
Davis, S. (2019). [Basketball Step Back] Business Insider. https://www.businessinsider.com/steph-curry-travel-james-harden-stepback-2019-1
Dos’Santos, T., Thomas, C., Comfort, P., & Jones, P. A. (2018). The effect of angle and velocity on change of direction biomechanics: An angle-velocity trade-off. Sports Medicine, 48, 2235-2253. Doi: https://doi.org/10.1007/s40279-018-0968-3
Falch, H. N., Raedergard, H. G., & Van den Tillaar, R. (2019). Effect of different physical training forms on change of direction ability: A systematic review and meta-analysis. Sports Medicine, 5(1), 53. Doi: https://doi.org/10.1186/s40798-019-0223-y
Maffiuletti, N. A., Aagaard, P., Blazevich, A. J., Folland, J., Tillin, N., & Duchateau, J. (2016). Rate of force development: Physiological and methodological considerations. European Journal of Applied Physiology, 116(6), 1091–1116. https://doi.org/10.1007/s00421-016-3346-6