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The zero-velocity update (ZUPT) method has become a popular approach to estimate foot kinematics from foot worn inertial measurement units (IMUs) during walking and running. However, the accuracy of the ZUPT method for stride parameters at sprinting speeds remains unknown, specifically when using sensors with characteristics well suited for sprinting (i.e., high accelerometer and gyroscope ranges and sampling rates). Seventeen participants performed 80-meter track sprints while wearing a Blue Trident IMeasureU IMU. Two cameras, at 20 and 70 meters from the start, were used to validate the ZUPT method on a stride-by-stride and on a cumulative distance basis. In particular, the validity of the ZUPT method was assessed for: (1) estimating a single stride length attained near the end of an 80m sprint (i.e., stride at 70m); (2) estimating cumulative distance from ∼20 to ∼70 m; and (3) estimating total distance traveled for an 80-meter track sprint. Individual stride length errors at the 70-meter mark were within -6% to 3%, with a bias of -0.27%. Cumulative distance errors were within -4 to 2%, with biases ranging from -0.85 to -1.22%. The results of this study demonstrate the ZUPT method provides accurate estimates of stride length and cumulative distance traveled for sprinting speeds. [ABSTRACT FROM AUTHOR]

This study aimed to quantify how ball flight kinematics (i.e., ball speed and movement), release location, and variations therein relate to pitching success in Major League Baseball (MLB). One hundred ninety starting MLB pitchers met the inclusion criteria for this study. Ball trajectory information was collected for 76,000 pitches and averaged across each pitcher before being inserted into a forward stepwise multiple regression model, which examined how (a) pitch selection, (b) ball speed, (c) ball movement (horizontal and lateral), (d) release location (horizontal and lateral), (e) variation in pitch speed, (f) variation in ball movement, and (g) variation in release location related to pitching success (as measured by fielding independent pitching-FIP). Pitch speed, release location variability, variation in pitch speed, and horizontal release location were significant predictors of FIP and, collectively, accounted for 24% of the variance in FIP. These findings suggest that (a) maximizing ball speed, (b) refining a consistent spatial release location, and (c) using varied pitch speeds should be primary foci for the pitching coach. However, between-pitcher variations underline how training interventions should be administered at the individual level, with consideration given to the pitcher's injury history. Finally, despite offering significant predictors of success, these three factors explained only 22% of the variance in FIP and should not be considered the only, or preeminent, indicators of a pitcher's effectiveness. Evidently, traditional pitching metrics only partly account for a pitcher's effectiveness, and future research is necessary to uncover the remaining contributors to success. [ABSTRACT FROM AUTHOR]

Abstract Recent evidence suggests that athletes are at a higher risk of lower-body injuries in the months and years following a concussion. However, little is known about how people modify their movements post-concussion. This study examined kinematics during a jump cut motion in young adults with a concussion history (n = 9; 4 males, 5 females; 3.1 years' post-injury) and 10 controls (6 males, 4 females). Peak center of mass and peak knee angles during the landing phase of a jump-cut maneuver were evaluated. Participants with a concussion history demonstrated decreased knee varus (left: M conc = − 0.5 ± 1.0°, M ctrl = 3.6 ± 1.0°; right: M conc = 5.1 ± 1.2°, M ctrl = 7.8 ± 1.12°) and external rotation (left: M conc = 2.5 ± 1.6°, M ctrl = 13.0 ± 1.5°; right: M conc = 7.7 ± 1.6°, M ctrl = 12.8 ± 1.5°) regardless of whether the cut was oriented towards to the left or right. The kinematic patterns demonstrated in individuals with a concussion history may be suggestive of increased knee injury risk. This study adds to the growing body of literature linking orthopedic injury in those no longer displaying the acute signs and symptoms of concussion. Highlights • A retrospective 3D motion captures evaluation of kinematic changes postconcussion. • Participants with a concussion history showed motor differences compared to controls years post injury. • These differences parallel the most common mechanism of ACL injury. [ABSTRACT FROM AUTHOR]