Fitts’s law states that movement time (MT) is related to precision (index of difficulty, ID). The introduction of a new effector in a Fitts’s task induces an increase of the MT/ID slopes (Langolf et al., 1976). It is unclear, however, whether kinetics or pure coordinative constraints based on the introduction of new degrees of freedom (at the joint or muscular level) are responsible for this effect. To determine the influence of body kinetics on the MT/ID slope when pointing beyond reach, we compared pointing movements executed within (control) or beyond reach, and in this latter case with (loaded) and without (distant) an additional mass applied to the trunk. Eight subjects were required to point as fast and as accurately as possible to a target (width: 0.5, 1.0, or 2.5 cm; amplitude: 30 cm). The MT/ID slope increased when pointing beyond reach (control versus distant or loaded). This slope did not increase with an additional load applied to the trunk (distant versus loaded). Therefore, we conclude that the MT/ID slope is more likely a function of the number of degrees of freedom introduced in the task rather than a function of the kinetics constraints.
Search Results
Pointing beyond Reach: The Slope of Fitts’s Law Increases with the Introduction of New Effectors Independently of Kinetic Constraints
François Bonnetblanc
Muscle–Tendon Behavior and Kinetics in Gastrocnemius Medialis During Forefoot and Rearfoot Strike Running
Tomonari Takeshita, Hiroaki Noro, Keiichiro Hata, Taira Yoshida, Tetsuo Fukunaga, and Toshio Yanagiya
and RFS, there is little information regarding muscle–tendon kinetics with consideration to the foot strike pattern while running. Based on computer simulations, only Yong et al 17 have reported higher negative work in the GM fascicle while FFS running compared with RFS running. They also revealed
Effect of the Fran CrossFit Workout on Oxygen Uptake Kinetics, Energetics, and Postexercise Muscle Function in Trained CrossFitters
Manoel Rios, Klaus Magno Becker, Ana Sofia Monteiro, Pedro Fonseca, David B. Pyne, Victor Machado Reis, Daniel Moreira-Gonçalves, and Ricardo J. Fernandes
Oxygen uptake ( V ˙ O 2 ) kinetics is a useful noninvasive measure of the integrated capacity to transport and utilize O 2 for increasing the rate of muscular energy turnover. 1 , 2 The scientific community has grouped and described the V ˙ O 2 kinetics during continuous exercise in 3 main
Effects of Hypoxia Severity on Muscle Oxygenation Kinetics Using Statistical Parametric Mapping During Repeated Treadmill Sprints
Clint Hansen, Franck Brocherie, Grégoire P. Millet, and Olivier Girard
the use of running modalities to evaluate RSA under hypoxic conditions, even though many popular sport activities (ie, team and racquet sports) predominantly take place on land. 7 The aim of this study was to examine the impact of different levels of hypoxia severity on oxygenation kinetics in the
A Biomechanical Analysis of Handcycling: A Case Study
Arnaud Faupin, Philippe Gorce, Eric Watelain, Christophe Meyer, and Andre Thevenon
The aim of this study was to investigate muscle activity, kinematic, and handgrip-force pattern generation during handcycling. One able-bodied participant performed a 1-min exercise test on a handcycle at 70 revolutions per minute. This article proposes an original data collection and analysis methodology that gathers synchronized kinematics, kinetics, and electromyography. Such data, which most often appear complex, are easily summarized using this methodology. This preliminary study has an new setup and offers good indications on the biomechanical pattern for handcycling movement analysis.
The Effect of Sex, Maturity, and Training Status on Maximal Sprint Performance Kinetics
Adam Runacres, Kelly A. Mackintosh, and Melitta A. McNarry
and training status. The development of speed throughout adolescence is a nonlinear process with cross-sectional evidence in untrained boys from nonmotorized treadmills suggesting that sprint kinetics (ie, force and power) only significantly increase from prepubertal to pubertal maturity statuses
Sex Differences During an Overhead Squat Assessment
Timothy C. Mauntel, Eric G. Post, Darin A. Padua, and David R. Bell
A disparity exists between the rates of male and female lower extremity injuries. One factor that may contribute to this disparity is high-risk biomechanical patterns that are commonly displayed by females. It is unknown what biomechanical differences exist between males and females during an overhead squat. This study compared lower extremity biomechanics during an overhead squat and ranges of motion between males and females. An electromagnetic motion tracking system interfaced with a force platform was used to quantify peak lower extremity kinematics and kinetics during the descent phase of each squat. Range of motion measurements were assessed with a standard goniometer. Differences between male and female kinematics, kinetics, and ranges of motion were identified with t tests. Males displayed greater peak knee valgus angle, peak hip flexion angle, peak vertical ground reaction forces, and peak hip extension moments. Males also displayed less active ankle dorsiflexion with the knee extended and hip internal and external rotation than females. No other differences were observed. The biomechanical differences between males and females during the overhead squat may result from differences in lower extremity ranges of motion. Therefore, sex-specific injury prevention programs should be developed to improve biomechanics and ranges of motion.
Lower-Extremity Kinetic Response to Activity Program Dosing in Older Adults
George J. Salem, Man-Ying Wang, Stanley P. Azen, Jean T. Young, and Gail A. Greendale
The purpose of this investigation was to determine the effects of two doses of a weighted vest on acute lower-extremity gait kinetics in older adults. Peak ankle, knee, and hip net joint moments were quantified in 56 men and women volunteers (73.8 ± 6.9 years old) enrolled in a 6-month physical activity study. At the initial study visit, participants underwent 6 walking trials (3 with vest, 3 without vest) at their normal pace. During the vest-wearing trials, participants wore a vest loaded with either 0% of body weight (BW) (n = 19), 3% of BW (n = 16), or 5% of BW (n = 21). With acute application of the vests, maximum peak plantarflexion moments increased by 5.7% in the 5% BW group compared to the 0% BW group, p < 0.01. Compared to the 0% vest-weight group, knee extension moments increased by 13.8% when 5% BW was applied, p < 0.01; a marginally significant treatment effect was evident in the 3% BW group, p = 0.04. Despite these acute alterations, knee strength and physical performance did not improve when subjects wore the vests 2 hours a day, 4 days a week for 27 weeks, without additional exercise prescription. These findings suggest that: (a) the acute changes in vest-mediated lower-extremity kinetics are not systemic but joint specific and load dependent, and (b) weighted vest prescription should be greater than 5% BW without prescribed exercise, or should include prescribed exercises, to invoke long-term strength and physical performance gains in older adults.
Intersession Variability of Knee Extension Kinetics Using a Strain Gauge Device With Differing Clinically Practical Physical Constraints
Christopher M. Juneau, Shelley N. Diewald, Jonathan Neville, John B. Cronin, and Dustin J. Oranchuk
the biomechanics and physiology of the musculotendinous 8 and nervous systems. 9 Assessing kinetics requires varying affordability and practicality technologies, contributing to the relative nonuse of rapid force metrics in physical medicine. 2 Gold standard equipment (ie
Long-Term Alterations in Pulmonary V ˙ O 2 and Muscle Deoxygenation On-Kinetics During Heavy-Intensity Exercise in Competitive Youth Cyclists: A Cohort Study
Matthias Hovorka, Bernhard Prinz, Dieter Simon, Manfred Zöger, Clemens Rumpl, and Alfred Nimmerichter
Pulmonary oxygen uptake ( V ˙ O 2 ) on-kinetics during step-transitions from rest to heavy-intensity cycling (ie, between the gas exchange threshold [GET] and critical power) are characterized by the following distinct phases ( 4 , 52 ): (1) the cardiodynamic phase (phase I), typically lasting 15
