326,375 research outputs found
Persistent fluctuations in stride intervals under fractal auditory stimulation
No full textCopyright @ 2014 Marmelat et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Stride sequences of healthy gait are characterized by persistent long-range correlations, which become anti-persistent in the presence of an isochronous metronome. The latter phenomenon is of particular interest because auditory cueing is generally considered to reduce stride variability and may hence be beneficial for stabilizing gait. Complex systems tend to match their correlation structure when synchronizing. In gait training, can one capitalize on this tendency by using a fractal metronome rather than an isochronous one? We examined whether auditory cues with fractal variations in inter-beat intervals yield similar fractal inter-stride interval variability as isochronous auditory cueing in two complementary experiments. In Experiment 1, participants walked on a treadmill while being paced by either an isochronous or a fractal metronome with different variation strengths between beats in order to test whether participants managed to synchronize with a fractal metronome and to determine the necessary amount of variability for participants to switch from anti-persistent to persistent inter-stride intervals. Participants did synchronize with the metronome despite its fractal randomness. The corresponding coefficient of variation of inter-beat intervals was fixed in Experiment 2, in which participants walked on a treadmill while being paced by non-isochronous metronomes with different scaling exponents. As expected, inter-stride intervals showed persistent correlations similar to self-paced walking only when cueing contained persistent correlations. Our results open up a new window to optimize rhythmic auditory cueing for gait stabilization by integrating fractal fluctuations in the inter-beat intervals.Commission of the European Community and the Netherlands Organisation for Scientific Research
CHANGES IN RUNNING GAIT PARAMETERS DURING A 161 KM TRAIL RACE
No full textThe current study examined changes in running speed and technique during a 161 km trail race and their relationship to performance. Sixteen participants were video recorded during continuous running for each of the five 32 km loops of the race. Participant's stride length (SL), stride rate (SR), and speed were calculated. Lap and finish times were also collated from the race results. All variables changed significantly during the race (i.e. Speed↓, Lap time↑, SL↓ and SR↓). Increased consistency in stride rate and length across the five laps, as well as speed, correlated positively with performance. Increased stride length in laps one, two and four correlated positively with performance. Results indicated that fatigue during the race decreased both speed and SL. Better performers ran faster with a longer SL and were able to maintain their initial speed for longer
Subject-specific values for stride-to-stride fluctuations (bit/s) and push-off work (J/kg).
No full textIndividual values for each leg (prosthesis side or sound side) and each condition (High Activity or Low Activity prosthesis) are reported. For stride-to-stride fluctuations, values were calculated at the ankle, knee, and hip. (XLSX)</p
Canals versus horses: political power in the oasis of Samarkand
No full textAt the heart of Central Asia, the Middle Zeravshan Valley and the city of Samarkand are
crisscrossed by a complex system of canals derived from the Zeravshan river (Fig. 1). In agreement
with the traditional theories proposed by soviet scholars and defended, in another context, by
Wittfogel, it is usually assumed that a strong, long-term association exists between the management
of this irrigation system and some form of centralized political power system.
By adopting an integrated approach, we will examine an alternative history of the emergence and
growth of Samarkand and the link between water management and socio-political power. In the first
part we will focus on the archaeological evidence pertaining to the construction of the Dargom, the
primary canal of Samarkand and suggest that it is not necessarily the result of a short-term (or fixed)
master plan or linked to a strong central political power. In the second part we will consider the nonirrigated
grasslands surrounding the oasis and show that the socio-political structures of the oasis
cannot be understood without a more systemic approach.
The paper is based on the results of an ongoing project to survey the Middle Zeravshan Valley
systematically initiated by the Institute of Archaeology of the Academy of Sciences of Uzbekistan in
collaboration with various international teams (see acknowledgements)
Estimation of temporal parameters during sprint running using a trunk-mounted inertial measurement unit
No full textThis research was supported by a grant of the Universit a Italo-Francese (Call Vinci) awarded to E. Bergamini.The purpose of this study was to identify consistent features in the signals supplied by a single inertial measurement unit (IMU), or thereof derived, for the identification of foot-strike and foot-off instants of time and for the estimation of stance and stride duration during the maintenance phase of sprint running. Maximal sprint runs were performed on tartan tracks by five amateur and six elite athletes, and durations derived from the IMU data were validated using force platforms and a high-speed video camera, respectively, for the two groups. The IMU was positioned on the lower back trunk (L1 level) of each athlete. The magnitudes of the acceleration and angular velocity vectors measured by the IMU, as well as their wavelet-mediated first and second derivatives were computed, and features related to foot-strike and foot-off events sought. No consistent features were found on the acceleration signal or on its first and second derivatives. Conversely, the foot-strike and foot-off events could be identified from features exhibited by the second derivative of the angular velocity magnitude. An average absolute difference of 0.005 s was found between IMU and reference estimates, for both stance and stride duration and for both amateur and elite athletes. The 95% limits of agreement of this difference were less than 0.025 s. The results proved that a single, trunk-mounted IMU is suitable to estimate stance and stride duration during sprint running, providing the opportunity to collect information in the field, without constraining or limiting athletes’ and coaches’ activities
Poslednie raboty po sosttavleniyu arkheologicheskikh kart Sredney Azii. Metody, rezultaty, perspektivy [Recent works on the creation of archaeological maps of Central Asia. Methods, Results, Perspectives]
No full textThe article presents an integrated approach used in the creation of the archaeological map of the Samarkand region (Uzbekistan
A floor sensor system for gait recognition
No full textThis paper describes the development of a prototype floor sensor as a gait recognition system. This could eventually find deployment as a standalone system (eg. a burglar alarm system) or as part of a multimodal biometric system. The new sensor consists of 1536 individual sensors arranged in a 3 m by 0.5 m rectangular strip with an individual sensor area of 3 cm2. The sensor floor operates at a sample rate of 22 Hz. The sensor itself uses a simple design inspired by computer keyboards and is made from low cost, off the shelf materials. Application of the sensor floor to a small database of 15 individuals was performed. Three features were extracted : stride length, stride cadence, and time on toe to time on heel ratio. Two of these measures have been used in video based gait recognition while the third is new to this analysis. These features proved sufficient to achieve an 80 % recognition rate
Working Data and Evaluation Data for STRIDE F4 Project (Project O6 uses same datasets)
No full text<p>As our STRIDE O6 project is the extension of F4. F4 and O6 utilized the same data, which composed of two datasets:</p>
<p>1. BSMP1.csv.zip is the working data. This data set was acquired by free download from DATA.GOV at:</p>
<p>https://catalog.data.gov/dataset/safety-pilot-model-deployment-data/resource/4029f4ea-43f6-4b2d-8a33-1c2b690ba416</p>
<p>As the data size is 55.71 GB, which exceeds the upload limit, we can not upload it here. Notice it can be downloaded free from the link above.</p>
<p>2. Export.7z is the evaluation data. This data was purchased from VITT. </p>
<p>Both datasets are in the format of CSV. For detail, please refer to our project final report.</p>
<p> </p>
To jog or to stride: A comparison between two standardised running tests to monitor neuromuscular status in team sport athletes
No full textThis study investigated: 1) monitoring post-match neuromuscular fatigue (NMF) status in rugby union players using two submaximal running tests (SRT); and 2) the sensitivity of each SRT to locomotor variables obtained during match-play. Twenty-three male rugby players (age: 21.0 ± 1.3 years; height: 185.2 ± 6.1 cm; body mass; 97.3 ± 10.3 kg) were monitored across one season (n = 71 player-match and 159 fatigue-players-testing observations). Two different SRTs (SRT-jog [5-minute shuttle run protocol] and SRT-stride [a repeat stride effort protocol]) were used to characterise post-match NMF, with measures taken two days prior to match day (baseline), on MD + 1, and MD + 2. Linear mixed models (±90% CIs) were used to explore differences between measures and match-play locomotor variables. SRT-jog presented a meaningful increase following MD + 1 (ES: 0.63 [0.37 to 0.89]). SRT-Stride showed small increases at MD + 1 (ES: 0.24 [0.02 to 0.49]) and MD + 2 (ES: 0.33 [0.07 to 0.59]) suggesting a potential impairment in running mechanics. SRT-stride was significantly associated with total distance (ES: 0.41 [−0.01 to 0.83]) and collisions (ES: 0.58 [0.18 to 0.99]). While both tests presented small to moderate changes post-match, only the SRT-stride was related to match locomotor variables. Therefore, the SRT-stride may be a more sensitive monitoring tool for monitoring NMF in rugby union players
STRIDE LENGTH/STRIDE FREQUENCY RATIO REMAINS CONSTANT UNDER DIFFERENT RUNNING CONDITIONS
No full textL. Reisch, C. Hixson, S. Ferguson, S. McCloughan, M. Conners, C. Kilborn, A. D. Gidley
Gonzaga University, Spokane, WA
Running kinematics are different when running on a level surface compared to on an incline. Additionally, each individual has his or her own preferred stride frequency, and most often this stride frequency is not energetically optimal but is something close. PURPOSE: The purpose of our study was to quantify the interaction between stride frequency and surface incline at preferred running speeds with natural stride frequencies and at a controlled stride frequency. METHODS: 12 participants of varying running experience (6 males and 6 females; 18-22 years old) participated in this study. Participants ran 5, 20-second trials on both a level and inclined road section. They then repeated these trials with a controlled stride frequency: 5% higher than their average preferred stride frequency. While running, each participant wore small data collection pods (RunScribe) from which several variables were recorded (Pace (PA), Stride Length (SL), Contact Time (CT), Flight Time (FT), Pace, Step Rate (SR), Footstrike (FS), Braking (BR), Impact (IM), Leg Stiffness (LS), Leg Vertical Stiffness (LVS), Vertical GRF Rate (VGRF), Horizontal GRF Rate (HGRF), and pelvic variables: Maximum Rotation (XR), Minimum Rotation (NR), Maximum Obliquity (XO), Minimum Obliquity (NO), Minimum tilt (NT), Maximum tilt (AT)). A repeated measures ANOVA was used to compare preferred and controlled stride frequency trials on the two surfaces for all variables (α=.05). RESULTS: SL, PA, SR, FS, BR, LS, LVS, VGRF, HGRF were all significantly greater in the controlled stride frequency trials than in the preferred stride frequency trials on flat ground (
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