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Andrea Biscarini

The author derived the exact analytical expression of the instantaneous joint power in exercises with single-joint, variable-resistance, selectorized strength-training equipment, taking into account all the relevant geometric, kinematic, and dynamic variables of both the movable equipment elements (resistance input lever, cam–pulley system, weight stack) and of the user’s exercising limb. A numerical algorithm was also designed to express, in the presence of a cam, the rectilinear kinematic variables of the weight stack as a function of the rotational kinematic variables of the resistance input lever, and vice versa. Given that information, one can measure the value of the instantaneous and mean joint power exclusively by means of a linear encoder placed on the weight stack or, alternatively, only by the use of an angular encoder placed on the rotational axis of the resistance lever. The results highlight that, for knee extension exercises with leg extension equipment, the real values of both instantaneous and mean joint power may differ by more than 50% in comparison with the values obtained by taking into account only the mass and velocity of the weight stack. These differences are notable not only in explosive exercises, but also whenever considerable joint velocities/accelerations occur within the range of motion.

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Assane E.S. Niang and Bradford J. McFadyen

The present study investigated the adaptations of specific power bursts during the combined contexts of the proximity (lead vs. trail limb) and height of an obstruction in relation to limb elevation versus progression. Ten young, adult, male subjects walked at their natural speed during unobstructed walking and the bilateral avoidance of moderate and high obstacles. Hip flexor generation power was unaffected by obstacle height for the leading limb and always delayed for the trailing limb. The knee extensor absorption power burst at toe-off was also eliminated for the trailing limb and was found to reappear in mid-swing. Few differences were seen for ankle push-off power. The results suggest that the hip joint is dedicated to limb advancement only, while the knee joint is directly involved in limb elevation and the control of multiarticular effects.

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Alejandro Pérez-Castilla, Belén Feriche, Slobodan Jaric, Paulino Padial and Amador García-Ramos

The force platform is recognized as the ‘gold standard’ for testing vertical jumps. 1 – 3 The force platform estimates the velocity and power of the system center of mass from the directly recorded vertical ground reaction force data using the direct dynamic approach. Due to potential

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Kajetan J. Słomka, Slobodan Jaric, Grzegorz Sobota, Ryszard Litkowycz, Tomasz Skowronek, Marian Rzepko and Grzegorz Juras

& Jaric, 2007 ) but also in routine testing of muscle mechanical capacities ( García-Ramos, Feriche, Pérez-Castilla, Padial, & Jaric, 2017 ; Markovic, Dizdar, Jukic, & Cardinale, 2004 ). A number of studies have assessed the force and power output produced in maximum vertical jumping either through

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Chee-Hoi Leong, Steven J. Elmer and James C. Martin

Researchers and bicycle component designers have sought to increase maximal cycling power by manipulating aspects of the pedaling motion, which include crank length, 1 novel crank-pedal mechanisms, 2 , 3 and chainring shape. 4 – 10 Noncircular chainrings (Figure  1 ) were initially described in

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Jorg Teichmann, Edin K. Suwarganda, C. Martyn Beaven, Kim Hébert-Losier, Jin Wei Lee, Florencio Tenllado Vallejo, Philip Chun Foong Lew, Ramlan Abdul Aziz, Yeo Wee Kian and Dietmar Schmidtbleicher

rehabilitation of anterior cruciate ligament injuries. 5 Specifically, measures of maximal leg strength and power were improved with a 3-week UDP in athletes that had been cleared to return to training following knee injury after having completed 4 phases of a rehabilitation program 4 : mobility; stability

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Mark G.L. Sayers and Stephen Bishop

Upper body power is a key component for success in many sports. Athletes who can generate high power output during throwing, catching, attacking, or defending activities are often capable of superior performance. 1 A common method for assessing upper body power has been via a bench press throw. 1

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Frank E. DiLiberto, Deborah A. Nawoczenski and Jeff Houck

, such as posterior tibialis tendon dysfunction, midfoot arthritis, and diabetes mellitus. 1 – 4 The importance of examining alterations in midfoot function, particularly as they pertain to foot power generation during push-off of forward propulsion, is underscored by the large contribution of ankle

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Frank E. DiLiberto and Deborah A. Nawoczenski

It is important to continue to expand the biomechanical profile of midfoot function beyond kinematics and include kinetic measurements, such as power. As the external measurements of power are representative of internal energy generating mechanisms, 1 incorporating kinetics into the biomechanical

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Harsh H. Buddhadev, Daniel L. Crisafulli, David N. Suprak and Jun G. San Juan

stationary cycling performed over 10 to 12 weeks led to a reduction in knee pain and stiffness, and improvement in walking speed and distance in individuals with knee OA. 8 , 9 Positive benefits of rehabilitation caused by cycling could be attributed to improvements in leg muscular power output and dynamic