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Hui Ying Wu, Jui Hung Tu, Chin Hsing Hsu and Te Hung Tsao

The effect of low-impact dance on blood metabolites, the joint range of motion (ROM) of the lower extremities, knee extension torque, bone mass density (BMD), the number of falls, and the confidence to perform daily activities (Modified Falls Efficacy Scale [MFES]) was examined in older sedentary women (age: 59 ± 4 years) before and after a 16-week intervention. Results showed that the average score for the MFES, some parameters of blood chemistry, and joint ROM were significantly improved after low-impact intervention. In addition to improvements in blood lipids and body fat percentages, the increases shown in the parameters regarding the lower extremities may contribute to confidence in performing common daily activities in older women, although the number of falls did not significantly differ between the two groups during the 16-week period.

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Ryoji Kiyama, Kiyohiro Fukudome, Toshiki Hiyoshi, Akihide Umemoto, Yoichi Yoshimoto and Tetsuo Maeda

The aim of this study was to examine the dexterity of both lower extremities in patients with stroke. Twenty patients with stroke and 20 age-matched control subjects participated in this study. To determine the dexterity of the lower extremities, we examined the ability to control muscle force during submaximal contractions in the knee extensor muscles using a force tracking task. The root mean square errors were calculated from the difference between the target and response force. The root mean square error was significantly greater in the affected limb of patients with stroke compared with those of the unaffected limb and the control subjects, and in the unaffected limb compared with that of the control subjects. Furthermore, the root mean square error of the affected limb was related significantly to motor function as determined by Fugl-Myer assessment. These results demonstrate impairment of the dexterity of both the affected and the unaffected lower extremities in patients with stroke.

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Felix Stief, Frank I. Kleindienst, Josef Wiemeyer, Florian Wedel, Sebastian Campe and Berthold Krabbe

Compared with walking (W), Nordic walking (NW) exhibits greater cardiopulmonary and cardiovascular benefits. Some authors conjecture that compared with W or running (R), NW imposes smaller mechanical loads on the musculoskeletal system. The purpose of the current study was to quantify any differences in joint loading of the lower extremities among NW, W, and R. Fifteen experienced adults participated. Kinematic and force measurements were combined using an inverse dynamics approach to yield joint moments. The results showed no biomechanical benefit of NW. Instead, NW involved greater knee joint loading just after heel strike compared with W. This was due to the longer steps and the higher sole angle during the first part of the stance phase. The sagittal and frontal plane moments were smaller for NW compared with R, but in the transverse plane, the ankle moments were greater in NW than in W or R. Based on these results, NW is not recommended as an exercise for persons who seek to reduce biomechanical loading of the lower extremities.

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Melissa M.B. Morrow, Wendy J. Hurd, Emma Fortune, Vipul Lugade and Kenton R. Kaufman

This study aimed to define accelerations measured at the waist and lower extremities over a range of gait velocities to provide reference data for choosing the appropriate accelerometer for field-based human activity monitoring studies. Accelerations were measured with a custom activity monitor (± 16g) at the waist, thighs, and ankles in 11 participants over a range of gait velocities from slow walking to running speeds. The cumulative frequencies and peak accelerations were determined. Cumulative acceleration amplitudes for the waist, thighs, and ankles during gait velocities up to 4.8 m/s were within the standard commercial g-range (± 6g) in 99.8%, 99.0%, and 96.5% of the data, respectively. Conversely, peak acceleration amplitudes exceeding the limits of many commercially available activity monitors were observed at the waist, thighs, and ankles, with the highest peaks at the ankles, as expected. At the thighs, and more so at the ankles, nearly 50% of the peak accelerations would not be detected when the gait velocity exceeds a walking velocity. Activity monitor choice is application specific, and investigators should be aware that when measuring high-intensity gait velocity activities with commercial units that impose a ceiling at ± 6g, peak accelerations may not be measured.

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Anne Sofie B. Malling, Bo M. Morberg, Lene Wermuth, Ole Gredal, Per Bech and Bente R. Jensen

standardized testing state with all measurements performed with the participant in an ON-state. The vast majority of the participants completed the tasks within one ON-cycle. Three motor tasks focused on gross motor skills in the lower extremities. The three tasks involved different levels of movement

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Xin He, Hio Teng Leong, On Yue Lau, Michael Tim-Yun Ong and Patrick Shu-Hang Yung

through neuromuscular exercises, 24 , 25 it is essential to understand the muscular strategy adopted by patients with ACLR during landing tasks, as rehabilitation can modify this outcome. The aim of this review was to evaluate the changes in neuromuscular activity of the lower-extremities during landing

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Ronald P. Pfeiffer, Kevin G. Shea, Michael J. Curtin and Peter Apel

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Olivier Seynnes, Olivier A. Hue, Frédéric Garrandes, Serge S. Colson, Pierre L. Bernard, Patrick Legros and Maria A. Fiatarone Singh

The relationship between isometric force control and functional performance is unknown. Submaximal steadiness and accuracy were measured during a constant force-matching task at 50% of maximal isometric voluntary contraction (MVC) of the knee extensors in 19 older women (70–89 years). Other variables included MVC, rate of torque development, and EMG activity. Functional performance was assessed during maximal performance of walking endurance, chair rising, and stair climbing. Isometric steadiness (but not accuracy) was found to independently predict chair-rise time and stair-climbing power and explained more variance in these tasks than any other variable. Walking endurance was related to muscle strength but not steadiness. These results suggest that steadiness is an independent predictor of brief, stressful functional-performance tasks in older women with mild functional impairment. Thus, improving steadiness might help reduce functional limitations or disability in older adults.

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Lars Janshen, Klaus Mattes and Günter Tidow

In sweep-oar rowers, asymmetrical force production of the legs is a known phenomenon. The purpose of this study was to investigate the muscular activity of the legs that may cause this asymmetry even when oarsmen perform a symmetrical endurance task. Seven male young elite oarsmen performed an all-out 2000-m test on a rowing ergometer. During stroke kinematics, myoelectric activity of six muscles of each leg and pressure distribution under both feet were measured. Data were collected over two 30-s time windows starting 1 and 5 min after the test started. No significant differences were observed between legs and time windows for the range of motion of the hip, knee, and ankle joint as well as for the onset/offset timing of muscles. However, in the drive phase, the knee and hip muscles of the leg on the oar side (inside leg) showed 20–45% (both p < .05) higher activation intensities compared with the leg opposite the oar (outside leg). Corresponding to this, 56–91% (both p < .05) higher mean pressure values under the ball of the inside foot compared with the outside foot indicated an asymmetrical force production of the legs even under kinematically symmetrical working conditions.

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Kristof Kipp, Josh Redden, Michelle Sabick and Chad Harris

The purpose of this study was to identify multijoint lower extremity kinematic and kinetic synergies in weight-lifting and compare these synergies between joints and across different external loads. Subjects completed sets of the clean exercise at loads equal to 65, 75, and 85% of their estimated 1-RM. Functional data analysis was used to extract principal component functions (PCF’s) for hip, knee, and ankle joint angles and moments of force during the pull phase of the clean at all loads. The PCF scores were then compared between joints and across loads to determine how much of each PCF was present at each joint and how it differed across loads. The analyses extracted two kinematic and four kinetic PCF’s. The statistical comparisons indicated that all kinematic and two of the four kinetic PCF’s did not differ across load, but scaled according to joint function. The PCF’s captured a set of joint- and load-specific synergies that quantified biomechanical function of the lower extremity during Olympic weightlifting and revealed important technical characteristics that should be considered in sports training and future research.