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D.S. Blaise Williams III, Jonathan H. Cole, and Douglas W. Powell

Running during sports and for physical activity often requires changes in velocity through acceleration and deceleration. While it is clear that lower extremity biomechanics vary during these accelerations and decelerations, the work requirements of the individual joints are not well understood. The purpose of this investigation was to measure the sagittal plane mechanical work of the individual lower extremity joints during acceleration, deceleration, and steady-state running. Ten runners were compared during acceleration, deceleration, and steady-state running using three-dimensional kinematics and kinetics measures. Total positive and negative joint work, and relative joint contributions to total work were compared between conditions. Total positive work progressively increased from deceleration to acceleration. This was due to greater ankle joint work during acceleration. While there was no significant change in total negative work during deceleration, there was a greater relative contribution of the knee to total negative work with a subsequent lower relative ankle negative work. Each lower extremity joint exhibits distinct functional roles in acceleration compared with deceleration during level running. Deceleration is dominated by greater contributions of the knee to negative work while acceleration is associated with a greater ankle contribution to positive work.

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Mohsen Shafizadeh, Nicola Theis, and Keith Davids

, since the capacity of certain tissues to transmit and attenuate shock may be frequency dependent ( Smeathers, 1989 ). The frequency content and signal power of impact shock and tibia acceleration during stance phase of normal running are thought to be governed primarily by movement of the leg and center

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Heidi R. Thornton, Jace A. Delaney, Grant M. Duthie, and Ben J. Dascombe

During the same training camp, 9 a research abstract showed that an increased acceleration/deceleration load (SumAccDec) was associated with very likely small increases in sleep duration (effect size [ES] = 0.27; ±0.16), time in bed (TIB; ES = 0.25; ±0.16), and sleep-onset latency (ES = 0.20; ±0

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Ted Polglaze and Matthias W. Hoppe

demands of brief, nonsteady-state—and often high-intensity—accelerations cannot be directly measured. However, this is possible for steady-state incline running, where energy cost increases with slope but, as per running on level ground, is independent of speed at a given slope. 5 Accordingly

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Aaron T. Scanlan, Robert Stanton, Charli Sargent, Cody O’Grady, Michele Lastella, and Jordan L. Fox

max ]) 4 demands while undertaking extensive physical requirements, including jumping (1.1 per min), accelerations (∼60), and change-of-direction movements (∼180) during game-play. 6 Despite the growing body of descriptive evidence quantifying game demands in basketball, the impact of overtime

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Jessica L. Trapp, Alicja B. Stannard, Julie K. Nolan, and Matthew F. Moran

positions ( Vescovi, 2012 ), the importance of rapid change of speed efforts (i.e., acceleration) and positional demands cannot be understated. With many deceleration efforts performed just prior to change of direction (COD) movements ( Bloomfield et al., 2007 ), the ability to train players appropriately

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Logan A. Lucas, Benjamin S. England, Travis W. Mason, Christopher R. Lanning, Taylor M. Miller, Alexander M. Morgan, and Thomas Gus Almonroeder

3 times an athlete’s body weight. 7 These impact forces generate a transient spike in acceleration which is transmitted throughout the musculoskeletal system from the foot to the head. 8 Although the lower-extremity musculature can help to attenuate these impact accelerations, passive tissues also

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Kevin G. Aubol, Jillian L. Hawkins, and Clare E. Milner

Tibial acceleration is thought to be related to overuse running injuries, particularly tibial stress fractures. 1 , 2 Peak axial tibial acceleration and peak resultant tibial acceleration are common outcome measures in studies of running. These measurements must be reliable so that the

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Garrett M. Hester, Zachary K. Pope, Mitchel A. Magrini, Ryan J. Colquhoun, Alejandra Barrera-Curiel, Carlos A. Estrada, Alex A. Olmos, and Jason M. DeFreitas

peak velocity (PV) and acceleration (sometimes termed rate of velocity development) of the knee extensors are negatively affected by age ( Thompson, Conchola, Palmer, & Stock, 2014 ; Wallace, Power, Rice, & Dalton, 2016 ). Similar to the effect of age on other rapid, time-sensitive measures (e

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Ryu Nagahara, Yohei Takai, Miki Haramura, Mirai Mizutani, Akifumi Matsuo, Hiroaki Kanehisa, and Tetsuo Fukunaga

in SL is caused by increases in height and/or relative vertical impulse. GRFs during the acceleration phase of sprinting largely change as propulsive forces decrease, and braking and vertical forces increase ( 14 ). Moreover, the difference in maximal speed results from the preceding difference in