The Experts below are selected from a list of 52845 Experts worldwide ranked by ideXlab platform
Philip Riches - One of the best experts on this subject based on the ideXlab platform.
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A comparison of Sprinting kinematics on two types of treadmill and over-ground.
Scandinavian journal of medicine & science in sports, 2007Co-Authors: M Mckenna, Philip RichesAbstract:Conventionally motorized treadmills elicit different Sprinting kinematics to the over-ground condition. Treadmills powered by a torque motor have been used to assess Sprinting power; yet, the kinematics of Sprinting on the torque treadmill are unknown. This study compares the Sprinting kinematics, during the constant velocity phase, between a conventional treadmill, a torque treadmill and the over-ground condition to assess the suitability of each treadmill for Sprinting studies and training. After familiarization, 13 recreationally active males performed multiple sprints at various experimental settings on each surface. Ninety sprints, which attained mean velocities over 7.0 m/s, had their lower-body sagittal plane joint angles during ground contact captured at 250 Hz. These data were low-pass filtered at 10 Hz, and compared with respect to surface, subject and velocity using an ANCOVA statistical model. Sprinting on the conventional treadmill elicited a longer ground contact time, a longer braking phase, a more extended knee at foot strike and a faster extending hip than the torque treadmill and over-ground (all P
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a comparison of Sprinting kinematics on two types of treadmill and over ground
Scandinavian Journal of Medicine & Science in Sports, 2007Co-Authors: M Mckenna, Philip RichesAbstract:Conventionally motorized treadmills elicit different Sprinting kinematics to the over-ground condition. Treadmills powered by a torque motor have been used to assess Sprinting power; yet, the kinematics of Sprinting on the torque treadmill are unknown. This study compares the Sprinting kinematics, during the constant velocity phase, between a conventional treadmill, a torque treadmill and the over-ground condition to assess the suitability of each treadmill for Sprinting studies and training. After familiarization, 13 recreationally active males performed multiple sprints at various experimental settings on each surface. Ninety sprints, which attained mean velocities over 7.0 m/s, had their lower-body sagittal plane joint angles during ground contact captured at 250 Hz. These data were low-pass filtered at 10 Hz, and compared with respect to surface, subject and velocity using an ANCOVA statistical model. Sprinting on the conventional treadmill elicited a longer ground contact time, a longer braking phase, a more extended knee at foot strike and a faster extending hip than the torque treadmill and over-ground (all P<0.05). The torque treadmill obtained an equivalent Sprinting technique to the over-ground condition, with the exception of a less extended hip at toe-off, suggesting that it is more appropriate for laboratory Sprinting analyses and training than the conventional treadmill.
M Mckenna - One of the best experts on this subject based on the ideXlab platform.
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A comparison of Sprinting kinematics on two types of treadmill and over-ground.
Scandinavian journal of medicine & science in sports, 2007Co-Authors: M Mckenna, Philip RichesAbstract:Conventionally motorized treadmills elicit different Sprinting kinematics to the over-ground condition. Treadmills powered by a torque motor have been used to assess Sprinting power; yet, the kinematics of Sprinting on the torque treadmill are unknown. This study compares the Sprinting kinematics, during the constant velocity phase, between a conventional treadmill, a torque treadmill and the over-ground condition to assess the suitability of each treadmill for Sprinting studies and training. After familiarization, 13 recreationally active males performed multiple sprints at various experimental settings on each surface. Ninety sprints, which attained mean velocities over 7.0 m/s, had their lower-body sagittal plane joint angles during ground contact captured at 250 Hz. These data were low-pass filtered at 10 Hz, and compared with respect to surface, subject and velocity using an ANCOVA statistical model. Sprinting on the conventional treadmill elicited a longer ground contact time, a longer braking phase, a more extended knee at foot strike and a faster extending hip than the torque treadmill and over-ground (all P
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a comparison of Sprinting kinematics on two types of treadmill and over ground
Scandinavian Journal of Medicine & Science in Sports, 2007Co-Authors: M Mckenna, Philip RichesAbstract:Conventionally motorized treadmills elicit different Sprinting kinematics to the over-ground condition. Treadmills powered by a torque motor have been used to assess Sprinting power; yet, the kinematics of Sprinting on the torque treadmill are unknown. This study compares the Sprinting kinematics, during the constant velocity phase, between a conventional treadmill, a torque treadmill and the over-ground condition to assess the suitability of each treadmill for Sprinting studies and training. After familiarization, 13 recreationally active males performed multiple sprints at various experimental settings on each surface. Ninety sprints, which attained mean velocities over 7.0 m/s, had their lower-body sagittal plane joint angles during ground contact captured at 250 Hz. These data were low-pass filtered at 10 Hz, and compared with respect to surface, subject and velocity using an ANCOVA statistical model. Sprinting on the conventional treadmill elicited a longer ground contact time, a longer braking phase, a more extended knee at foot strike and a faster extending hip than the torque treadmill and over-ground (all P<0.05). The torque treadmill obtained an equivalent Sprinting technique to the over-ground condition, with the exception of a less extended hip at toe-off, suggesting that it is more appropriate for laboratory Sprinting analyses and training than the conventional treadmill.
Milo M.k. Martin - One of the best experts on this subject based on the ideXlab platform.
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utilizing dark silicon to save energy with computational Sprinting
IEEE Micro, 2013Co-Authors: Arun Raghavan, Laurel Emurian, Lei Shao, Marios Papaefthymiou, Kevin P. Pipe, Thomas F. Wenisch, Milo M.k. MartinAbstract:Computational Sprinting activates dark silicon to improve responsiveness by briefly but intensely exceeding a system's sustainable power limit. This article focuses on the energy implications of Sprinting. The authors observe that Sprinting can save energy even while improving responsiveness by enabling execution in chip configurations that, though thermally unsustainable, improve energy efficiency. Surprisingly, this energy savings can translate to throughput improvements even for long-running computations. Repeatedly alternating between sprint and idle modes while maintaining sustainable average power can outperform steady-state computation at the platform's thermal limit.
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Computational Sprinting on a hardware/software testbed
ACM SIGARCH Computer Architecture News, 2013Co-Authors: Arun Raghavan, Laurel Emurian, Lei Shao, Marios Papaefthymiou, Kevin P. Pipe, Thomas F. Wenisch, Milo M.k. MartinAbstract:CMOS scaling trends have led to an inflection point where thermal constraints (especially in mobile devices that employ only passive cooling) preclude sustained operation of all transistors on a chip --- a phenomenon called "dark silicon." Recent research proposed computational Sprinting --- exceeding sustainable thermal limits for short intervals --- to improve responsiveness in light of the bursty computation demands of many media-rich interactive mobile applications. Computational Sprinting improves responsiveness by activating reserve cores (parallel Sprinting) and/or boosting frequency/voltage (frequency Sprinting) to power levels that far exceed the system's sustainable cooling capabilities, relying on thermal capacitance to buffer heat. Prior work analyzed the feasibility of Sprinting through modeling and simulation. In this work, we investigate Sprinting using a hardware/software testbed. First, we study unabridged sprints, wherein the computation completes before temperature becomes critical, demonstrating a 6.3x responsiveness gain, and a 6% energy efficiency improvement by racing to idle. We then analyze truncated sprints, wherein our software runtime system must intervene to prevent overheating by throttling parallelism and frequency before the computation is complete. To avoid oversubscription penalties (context switching inefficiencies after a truncated parallel sprint), we develop a sprint-aware task-based parallel runtime. We find that maximal-intensity Sprinting is not always best, introduce the concept of sprint pacing, and evaluate an adaptive policy for selecting sprint intensity. We report initial results using a phase change heat sink to extend maximum sprint duration. Finally, we demonstrate that a sprint-and-rest operating regime can actually outperform thermally-limited sustained execution.
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computational Sprinting on a hardware software testbed
Architectural Support for Programming Languages and Operating Systems, 2013Co-Authors: Arun Raghavan, Laurel Emurian, Lei Shao, Marios Papaefthymiou, Kevin P. Pipe, Thomas F. Wenisch, Milo M.k. MartinAbstract:CMOS scaling trends have led to an inflection point where thermal constraints (especially in mobile devices that employ only passive cooling) preclude sustained operation of all transistors on a chip --- a phenomenon called "dark silicon." Recent research proposed computational Sprinting --- exceeding sustainable thermal limits for short intervals --- to improve responsiveness in light of the bursty computation demands of many media-rich interactive mobile applications. Computational Sprinting improves responsiveness by activating reserve cores (parallel Sprinting) and/or boosting frequency/voltage (frequency Sprinting) to power levels that far exceed the system's sustainable cooling capabilities, relying on thermal capacitance to buffer heat. Prior work analyzed the feasibility of Sprinting through modeling and simulation. In this work, we investigate Sprinting using a hardware/software testbed. First, we study unabridged sprints, wherein the computation completes before temperature becomes critical, demonstrating a 6.3x responsiveness gain, and a 6% energy efficiency improvement by racing to idle. We then analyze truncated sprints, wherein our software runtime system must intervene to prevent overheating by throttling parallelism and frequency before the computation is complete. To avoid oversubscription penalties (context switching inefficiencies after a truncated parallel sprint), we develop a sprint-aware task-based parallel runtime. We find that maximal-intensity Sprinting is not always best, introduce the concept of sprint pacing, and evaluate an adaptive policy for selecting sprint intensity. We report initial results using a phase change heat sink to extend maximum sprint duration. Finally, we demonstrate that a sprint-and-rest operating regime can actually outperform thermally-limited sustained execution.
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computational Sprinting
High-Performance Computer Architecture, 2012Co-Authors: Arun Raghavan, Marios Papaefthymiou, Kevin P. Pipe, Thomas F. Wenisch, Yixin Luo, Anuj Chandawalla, Milo M.k. MartinAbstract:Although transistor density continues to increase, voltage scaling has stalled and thus power density is increasing each technology generation. Particularly in mobile devices, which have limited cooling options, these trends lead to a utilization wall in which sustained chip performance is limited primarily by power rather than area. However, many mobile applications do not demand sustained performance; rather they comprise short bursts of computation in response to sporadic user activity. To improve responsiveness for such applications, this paper explores activating otherwise powered-down cores for sub-second bursts of intense parallel computation. The approach exploits the concept of computational Sprinting, in which a chip temporarily exceeds its sustainable thermal power budget to provide instantaneous throughput, after which the chip must return to nominal operation to cool down. To demonstrate the feasibility of this approach, we analyze the thermal and electrical characteristics of a smart-phone-like system that nominally operates a single core (~1W peak), but can sprint with up to 16 cores for hundreds of milliseconds. We describe a thermal design that incorporates phase-change materials to provide thermal capacitance to enable such sprints. We analyze image recognition kernels to show that parallel Sprinting has the potential to achieve the task response time of a 16W chip within the thermal constraints of a 1W mobile platform.
Nicholas P Linthorne - One of the best experts on this subject based on the ideXlab platform.
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effects of a sand running surface on the kinematics of Sprinting at maximum velocity
Biology of Sport, 2011Co-Authors: Pedro E. Alcaraz, Jose M Palao, Jll Elvira, Nicholas P LinthorneAbstract:Performing sprints on a sand surface is a common training method for improving sprint-specific strength. For maximum specificity of training the athlete's movement patterns during the training exercise should closely resemble those used when performing the sport. The aim of this study was to compare the kinematics of Sprinting at maximum velocity on a dry sand surface to the kinematics of Sprinting on an athletics track. Five men and five women participated in the study, and flying sprints over 30 m were recorded by video and digitized using biomechanical analysis software. We found that Sprinting on a sand surface was substantially different to Sprinting on an athletics track. When Sprinting on sand the athletes tended to 'sit' during the ground contact phase of the stride. This action was characterized by a lower centre of mass, a greater forward lean in the trunk, and an incomplete extension of the hip joint at take-off. We conclude that Sprinting on a dry sand surface may not be an appropriate method for training the maximum velocity phase in Sprinting. Although this training method exerts a substantial overload on the athlete, as indicated by reductions in running velocity and stride length, it also induces detrimental changes to the athlete's running technique which may transfer to competition Sprinting.
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Effects of Three Types of Resisted Sprint Training Devices on the Kinematics of Sprinting at Maximum Velocity
Journal of strength and conditioning research, 2008Co-Authors: Pedro E. Alcaraz, José Manuel Palao, José Luis López Elvira, Nicholas P LinthorneAbstract:Resisted sprint running is a common training method for improving sprint-specific strength. For maximum specificity of training, the athlete's movement patterns during the training exercise should closely resemble those used when performing the sport. The purpose of this study was to compare the kinematics of Sprinting at maximum velocity to the kinematics of Sprinting when using three of types of resisted sprint training devices (sled, parachute, and weight belt). Eleven men and 7 women participated in the study. Flying sprints greater than 30 m were recorded by video and digitized with the use of biomechanical analysis software. The test conditions were compared using a 2-way analysis of variance with a post-hoc Tukey test of honestly significant differences. We found that the 3 types of resisted sprint training devices are appropriate devices for training the maximum velocity phase in Sprinting. These devices exerted a substantial overload on the athlete, as indicated by reductions in stride length and running velocity, but induced only minor changes in the athlete's running technique. When training with resisted sprint training devices, the coach should use a high resistance so that the athlete experiences a large training stimulus, but not so high that the device induces substantial changes in Sprinting technique. We recommend using a video overlay system to visually compare the movement patterns of the athlete in unloaded Sprinting to Sprinting with the training device. In particular, the coach should look for changes in the athlete's forward lean and changes in the angles of the support leg during the ground contact phase of the stride.
Andrew J. Harrison - One of the best experts on this subject based on the ideXlab platform.
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muscle activity in Sprinting a review
Sports Biomechanics, 2018Co-Authors: Roisin Marie Howard, Richard Conway, Andrew J. HarrisonAbstract:The use of electromyography (EMG) is widely recognised as a valuable tool for enhancing the understanding of performance drivers and potential injury risk in Sprinting. The timings of muscle activations relative to running gait cycle phases and the technology used to obtain muscle activation data during Sprinting are of particular interest to scientists and coaches. This review examined the main muscles being analysed by surface EMG (sEMG), their activations and timing, and the technologies used to gather sEMG during Sprinting. Electronic databases were searched using 'Electromyography' OR 'EMG' AND 'running' OR 'Sprinting'. Based on inclusion criteria, 18 articles were selected for review. While sEMG is widely used in biomechanics, relatively few studies have used sEMG in Sprinting due to system constraints. The results demonstrated a focus on the leg muscles, with over 70% of the muscles analysed in the upper leg. This is consistent with the use of tethered and data logging EMG systems and many sprints being performed on treadmills. Through the recent advances in wireless EMG technology, an increase in the studies on high velocity movements such as Sprinting is expected and this should allow practitioners to perform the analysis in an ecologically valid environment.
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Resisted sprints do not acutely enhance Sprinting performance.
Journal of strength and conditioning research, 2014Co-Authors: Niamh Whelan, Ciaran Oʼregan, Andrew J. HarrisonAbstract:Sprinting speed is a vital component of successful performance in many sports. Long-term resisted sprint training has been shown to improve early acceleration performance, but the acute post-activation potentiation (PAP) effects of resisted Sprinting on subsequent performance remain unclear. The purpose of this investigation was to examine the effects of resisted Sprinting on Sprinting and factors related to sprint performance. Twelve active males participated in a pretest involving ten 10-m sprints through dual-beam timing gates and 10-m Optojump Next System with full recovery. This provided baseline data on step rate, step length, ground contact time, and running speed over the first 6 steps of a maximum effort sprint. One week later, the participants performed three 10-m resisted sprints using a sled loaded to 25-30% body mass followed by a 10-m sprint at 1, 2, 4, 6, 8, and 10 minutes after the final resisted sprint. The data were analyzed using an adapted typical error analysis and repeated measures analysis of variance. The results using analysis of variance provided evidence of significant initial fatigue followed by the enhancement of mean step rate, contact time, reactive strength index, and running speed in 10-m sprints performed after the resisted Sprinting (p > 0.05). By contrast, the typical error analysis showed that this enhancement was limited and unsystematic in nature with little clear evidence of fatigue followed by potentiation. The results using typical error data do not provide strong evidence of PAP in 10-m sprint performance after resisted Sprinting.
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BIOMECHANICAL FACTORS IN SPRINT TRAINING- WHERE SCIENCE MEETS COACHING.
2010Co-Authors: Andrew J. HarrisonAbstract:This paper examines the biomechanics of Sprinting and sprint training. Various biomechanical models of sprint performance are considered with respect to the start ,acceleration and speed maintenance phases of the 100 m sprint event together with the research that underpins those models. The impact of research on strength and conditioning training is discussed with special reference to the control of leg-spring stiffness and the applications of resistance and complex training modalities. Training practises for Sprinting are discussed with respect to scientific evidence. The relevance of commonly used sprint and running drills is evaluated in relation to the kinematics and muscle activation patterns in Sprinting. Finally, a simple coaching related model for the development of Sprinting is presented which is consistent with scientific evidence.
