running speeds, and decreases thereafter until maximal running speed is reached. 9 , 18 In contrast, both braking and propulsive impulses increase with increasing steady running speed, although published data exist only for speeds up to 7 m/s. 12 , 15 These impulses reflect a large decrease and then
Ryu Nagahara, Mirai Mizutani, Akifumi Matsuo, Hiroaki Kanehisa, and Tetsuo Fukunaga
Elizabeth J. Bradshaw and W.A. Sparrow
Adjustments to gait were examined when positioning the foot within a narrow target at the end of an approach for two impact conditions, hard and soft. Participants (6 M, 6 F) ran toward a target of three lengths along a 10-m walkway consisting of two marker strips with alternating black and white 0.5-m markings. Five trials were conducted for each target length and impact task, with trials block randomized between the 6 participants of each gender. A 50Hz digital video camera panned and filmed each trial from an elevated position adjacent to the walkway. Video footage was digitized to deduce the gait characteristics. A linear speed/accuracy tradeoff between target length and approach time was found for both impact tasks (hard, r = 0.99, p < 0.01; soft, r = 0.96, p < 0.05). For the hard-impact task, visual control time increased linearly (r = 0.99, p < 0.05) when whole-body approach velocity decreased. Visual control time was unaffected by whole-body approach velocity in the soft-impact task. A constant tau-margin of 1.08 describes the onset of visual control when approaching a target while running, with the control of braking during visual control described by a tau-dot of –0.85. Further research is needed to examine the control of braking in different targeting tasks.
Gunnar Treff, Kay Winkert, Katja Machus, and Jürgen M. Steinacker
mechanical power output. 1 , 2 These so-called ramp tests are usually performed on cycle ergometers, where mechanical power output is externally controllable, as resistance is induced by, for example, eddy-current or magnetic brakes and furthermore controlled for cadence. In contrast, mechanical power
Pauline Maillot, Alexandra Perrot, Alan Hartley, and Manh-Cuong Do
The purposes of this present research were, in the first study, to determine whether age impacts a measure of postural control (the braking force in walking) and, in a second study, to determine whether exergame training in physically-simulated sport activity would show transfer, increasing the braking force in walking and also improving balance assessed by clinical measures, functional fitness, and health-related quality of life in older adults. For the second study, the authors developed an active video game training program (using the Wii system) with a pretest-training-posttest design comparing an experimental group (24 1-hr sessions of training) with a control group. Participants completed a battery comprising balance (braking force in short and normal step conditions), functional fitness (Senior Fitness Test), and health-related quality of life (SF-36). Results show that 12 weeks of video game-based exercise program training improved the braking force in the normal step condition, along with the functional fitness of lower limb strength, cardiovascular endurance, and motor agility, as measured by the Senior Fitness Test. Only the global mental dimension of the SF-36 was sensitive to exergame practice. Exergames appear to be an effective way to train postural control in older adults. Because of the multimodal nature of the activity, exergames provide an effective tool for remediation of age-related problems.
Rebecca Fernandes, Chris Bishop, Anthony N. Turner, Shyam Chavda, and Sean J. Maloney
was conducted in male academy soccer players, an influence of maturation status cannot be discounted. Where athletes carry greater momentum into a COD, they must exert a larger braking impulse to overcome this. While Young et al 4 proposed the importance of strength to CODS ability, strength may be
Lee N. Burkett, Jack Chisum, Ralph Cook, Bob Norton, Bob Taylor, Keith Ruppert, and Chris Wells
Numerous studies in the past 30 years have researched physiological adaptation to stress by wheelchair-bound subjects. Instrumentation necessary to produce this effect had to be designed and tested prior to obtaining valid data. This study had two main purposes: to design a wheelchair ergometer for physiological testing of spinal cord-injured subjects, and to demonstrate the validity of the maximal stress test when using the wheelchair ergometer. To test the validity of the wheelchair ergometer, 10 disabled subjects (9 paraplegic and 1 quadriplegic) participated in both a maximal field test (FT) and a maximal wheelchair ergometer test (WERG), with each subject serving as his or her own control. A randomly assigned counterbalanced design (5 subjects assigned to complete the FT first, with the second group of 5 subjects completing the WERG first) was used to reduce the learning effect in the study. The results of the t-tests indicated there was no significant difference between V̇O2 and V̇E, (STPD) averages for the WERG and FT for maximal effort with two-tailed significant levels of t = .9016 and t = .7294, respectively. The Pearson product moment correlation level was statistically significant at p < .0001, when the WERG V̇O2 was compared to the FT V̇O2 (r = .94), and was significant at p < .005 when the WERG V̇E was compared to the FT V̇E (r = .82).
Jason Lake, Peter Mundy, Paul Comfort, John J. McMahon, Timothy J. Suchomel, and Patrick Carden
Committee. Participants performed 4 bilateral CMJ, interspersed with 30 seconds of rest. They were instructed to stand still until given the word of command to “jump,” where they performed a rapid countermovement to a comfortable depth that enabled them to perform the transition from braking to propulsion
Prasanna Sritharan, Luke G. Perraton, Mario A. Munoz, Peter Pivonka, and Adam L. Bryant
individuals. 3 Landing from a single-leg hop demands a highly specific neuromuscular control strategy to arrest forward momentum of the body center of mass while preventing the stance limb from collapsing under the body’s weight, 4 , 5 known as center-of-mass braking and support, respectively. During
Christopher Napier, Christopher L. MacLean, Jessica Maurer, Jack E. Taunton, and Michael A. Hunt
braking force may also be an important risk factor for running-related injury, with higher braking forces resulting in risk of injury 5 to 8 times that of lower braking forces. Recently, running gait retraining has become a popular mode of treatment for running injuries, with promising results. 14 , 15