This study examines how adults apply forces to regulate new walkers’ body sway directions while assisting them in standing and initiating their first steps. Eight healthy, typically developing young children who could stand independently and walk a few steps with an adult’s support participated in this study and were included for data analyses. Adults wore instrumented force gloves and placed their hands on their child’s hips to assist them in standing, then released glove contact with their child to allow their child to initiate walking. Using the glove force profiles, three phases (Stabilization, Relaxation, and Initiation) of adults’ support were determined. Results showed that adults gradually reduced their assistance in both the antero-posterior (AP) and mediolateral (ML) directions, before releasing their hands. They also influenced the directionality of their child’s center of mass (CoM) so that it was in the AP rather than ML direction. Furthermore, the behavior of the child’s CoM in the ML direction during the Initiation Phase was related to the latency with which the child initiated the first step. These findings support the view that adults play a role in modulating the directionality of the child’s body motion by transforming body sway into gait initiation.
Wen-Hao Hsu, Evelyn J. Park, Daniel L. Miranda, Hani M. Sallum, Conor J. Walsh and Eugene C. Goldfield
Wen-Hao Hsu, Daniel Miranda, Diana Young, Kelly Cakert, Mona Qureshi and Eugene Goldfield
We conducted a longitudinal kinematic study of spontaneous arm and leg motions in 4 supine infants at 3, 4½, and 6 months of age. The study addressed two questions: (a) whether there was a longitudinal change in the synchronization of joint rotations at the hips, knees, shoulders, and elbows, indicating that the arms and legs were moving more independently of each other; and (b) whether, during this period, the spatial location of the hands relative to the shoulders was different from that of the feet relative to the hips, indicating that the infants were beginning to use their upper limbs differently than their lower limbs. We found that, in general, the arms and legs were moving more independently of each other by 6 months of age. At the same time, the infants were more likely to hold their hands away from the body in preparation for making contact with an object in the midline, but they brought their feet close to the body to maximize propulsive kicks. Thus, a reorganization of the relative timing of joint rotations appears to be related to the emergence of different arm and leg functions.
Jenya Iuzzini-Seigel, Tiffany P. Hogan, Panying Rong and Jordan R. Green
Lip shape in adult talkers is primarily driven by vertical opening; however, little is known about how children converge on this highly organized and efficient lip shape pattern. This longitudinal study investigated the development of lip shape control and its relation to speech and vocabulary acquisition in 28 typically developing children between 3 months and 5 years of age. Results suggested that during infancy lip shape was characterized by horizontal spreading of the lips, but that the contribution of vertical opening increased nonmonotonically over time. This change co-occurred with gains in expressive communication. These data suggest that lip shape may represent an important marker of normal oromotor development. Future work is required to determine the functional significance of the observed changes in lip shape control for identifying children at risk for speech and language impairments.
Geoffrey T. Burns, Kenneth M. Kozloff and Ronald F. Zernicke
Movement is essential to the human experience, and efficient biomechanics facilitate effective action across the breadth of tasks one encounters in life. The concept of movement efficiency has been investigated and explored through a variety of means including biomechanical modeling, simulation, and experimental manipulation. Observations of elite performers for a given movement task serve as an additional line of insight into efficiency, as their movements have been driven toward optimization via competitive pressure. The authors first discuss the concept of efficiency in biomechanics from a qualitative perspective and the broad tools with which we explore it. They then highlight biomechanical investigations of elite performers and their contributions to our understanding of efficiency. Examples from various classes of movements illustrate unique insights of the elite performers in informing our understanding of movement efficiency.
Hwang-Jae Lee, Won Hyuk Chang, Sun Hee Hwang, Byung-Ok Choi, Gyu-Ha Ryu and Yun-Hee Kim
The purpose of this study was to examine age-related gait characteristics and their associations with balance function in older adults. A total of 51 adult volunteers participated. All subjects underwent locomotion analysis using a 3D motion analysis and 12-channel dynamic electromyography system. Dynamic balance function was assessed by the Berg Balance Scale. Older adults showed a higher level of muscle activation than young adults, and there were significant positive correlations between increased age and activation of the trunk and thigh muscles in the stance and swing phase of the gait cycle. In particular, back extensor muscle activity was mostly correlated with the dynamic balance in older adults. Thus, back extensor muscle activity in walking may provide a clue for higher falling risk in older adults. This study demonstrates that the back extensor muscles play very important roles with potential for rehabilitation training to improve balance and gait in older adults.
Kelsey Lucca, David Gire, Rachel Horton and Jessica A. Sommerville
standardized measures of behavior. These techniques have led to critical scientific breakthroughs in infant motor development. For example, in an experiment conducted by Thelen et al. ( 1987 ), a 3D motion analysis of 7-month-olds’ leg movements on a treadmill revealed that interlimb coordination is a core
Daniel Leightley, Moi Hoon Yap, Jessica Coulson, Mathew Piasecki, James Cameron, Yoann Barnouin, Jon Tobias and Jamie S. McPhee
the research laboratory at Manchester Metropolitan University Postural Sway and Motion Analysis Data Capture The balance and sit-to-stand assessments (described in more detail below) were selected because they form core parts of the short physical performance test battery commonly used to assess
Christopher J. Nightingale, Sidney N. Mitchell and Stephen A. Butterfield
system can measure changes in foot position, flight time, and movement variations to within 0.001 s. Data are then analyzed by specialized software for the purpose of motion analysis and presented as means, SD s, and variability coefficients for different spatiotemporal parameters of gait. OptoGait has
AmirAli Jafarnezhadgero, Morteza Madadi-Shad, Christopher McCrum and Kiros Karamanidis
successful landings were recorded. Any fatigue effects were mitigated by each subject resting for at least 60 s between each of landing trials ( Niu, Wang, He, Fan, & Zhao, 2011 ). Position coordinate data of the markers were collected using six Vicon cameras at a sampling rate of 200 Hz (Motion Analysis
Harsh H. Buddhadev and Philip E. Martin
calibrated with known gas concentrations (20.99% ± 0.03% O 2 and 5.03% ± 0.03% CO 2 ) and a 3-L calibration syringe. Two passive reflective markers were attached to the lateral face of the left pedal and were subsequently used to distinguish individual crank revolutions using a Vicon motion analysis system