The evaluation of a vector coding technique to quantify intersegmental coupling within a limb over multiple cycles of walking is described. The angular position of the knee with respect to the hip during walking was examined based on relative motion plots generated from videographic data. Participants included one able-bodied individual and one with spinal cord injury; the latter was assessed before and after participating in an assisted walking program. Vector coding of the frame-to-frame changes in hip/knee relationship was used to quantify the relative motion plots. Vector analysis techniques were then used to produce a single value that represents the overall variability of the hip/knee coupling relationship over multiple cycles. Hypothetical and random data were also used to evaluate the coding algorithm. In addition, the technique was compared to an earlier method in the analysis of this same data. Vector coding provided an easily interpretable method of quantifying the intersegmental coupling relationships and assessing the degree of consistency in the intralimb coordination over multiple cycles. The measure is sensitive to change in the kinematic variables and appears to have good validity. In addition, this technique has advantages over prior techniques as it allows simultaneous comparison of multiple cycles, calculations are performed quickly, and the algorithm is easy to program.
Dejan Tepavac and Edelle Carmen Field-Fote
Bryan C. Heiderscheit, Joseph Hamill and Richard E.A. van Emmerik
The purpose of this investigation was to determine whether individuals with patellofemoral pain (PFP) display a reduction in intralimb joint coordination variability compared to nonimpaired persons. In addition, it was hypothesized that the variability of the stride characteristics would be similar between groups. Eight individuals with unilateral PFP and 8 nonimpaired participants ran on a treadmill at a fixed (2.68 m·s–1) and preferred speed while stride characteristics and 3-D kinematics of the bilateral lower extremities were recorded. Intralimb coordination variability was measured using a vector coding technique applied to relative motion plots of various joint couplings. The PFP group displayed greater stride length variability during running at the preferred speed. However, this was not the case during running at the fixed speed. When averaging across the entire stride cycle, coordination variability for all joint couplings was consistent between the two groups. However, further analysis about heel-strike revealed reduced joint coordination variability for the thigh rotation/leg rotation coupling of the PFP group’s injured limb compared to that of the nonimpaired group. With the exception of the transverse plane rotations at heel-strike, it would appear that the level of pain experienced by the PFP participants may not be great enough to produce a change in the intralimb coordination patterns during running.
Wataru Kawakami, Makoto Takahashi, Yoshitaka Iwamoto and Koichi Shinakoda
midfoot motion during gait. They expressed the forefoot motion as relative motion compared with the rearfoot. However, the forefoot is adjacent to the midfoot, and not adjacent to the rearfoot. Leardini et al 19 suggested a multisegment foot model with definition of the midfoot segment, and they observed
Karine Jacon Sarro, Amanda Piaia Silvatti, Andrea Aliverti and Ricardo M. L. Barros
A novel method based on kinematical analysis is proposed to describe the three-dimensional motion of the ribs during breathing. The three-dimensional coordinates of markers on the ribs and vertebrae were used to calculate the orientation of the ribs as a function of time. A test measured the relative motion between the markers and the ribs using magnetic resonance and the results revealed that the skin motion artifact found for the ribs (absolute mean value 3.9 mm) would induce maximum errors of 4° on rib motion calculation. The method identified a signal coherent with the breathing cycle for the angles of the ribs around the mediolateral axis and was also able to show differences between healthy nonathletes and swimmers, which presented greater angular variation of the ribs (p < .05). In conclusion, this study has shown the reliability of using three-dimensional kinematic analysis to evaluate the movement of the ribs during breathing as well as its potential to identify differences in the behavior of the rib motion in trained swimmers and untrained healthy subjects.
Julia Freedman Silvernail, Richard E.A. van Emmerik, Katherine Boyer, Michael A. Busa and Joseph Hamill
coupling angle represents the relative motion of the segments of interest, initial studies considered all possible coupling angles resulting in a range from 0° to 360°. 1 , 2 , 8 Due to the directionality of the data, they are inherently circular, meaning that a value of 0° is not different from a value
Nicholas J. Smeeton, Matyas Varga, Joe Causer and A. Mark Williams
and textures, have been used to show that intentions can be recognized without this information ( Abernethy, Gill, Parks, & Packer, 2001 ; Ward, Williams, & Bennett, 2002 ). These published reports show that the relative motion profile of the action contains the information upon which intentions can
John M. Rosene, Christian Merritt, Nick R. Wirth and Daniel Nguyen
acceleration, the use of headgear-mounted devices (e.g., SIM) has demonstrated subpar accuracy in recording linear and rotational acceleration and high relative motion of the device while worn on the head. 20 , 21 Finally, at the time this pilot project was conducted we did not have the ability to video
Wen-Hao Hsu, Evelyn J. Park, Daniel L. Miranda, Hani M. Sallum, Conor J. Walsh and Eugene C. Goldfield
the AP or ML direction (Table 3 ). This finding suggests that the range of the child’s CoM movement was not limited by the modulation of the assistance from the adult. However, the analyses on the relative motion between the ML and AP direction revealed that there was a significant difference between
Tzu-Chieh Liao, Joyce H. Keyak and Christopher M. Powers
. As tibiofemoral joint rotation in the transverse plane is the result of relative motion of the femur and tibia, knee external rotation could result from external rotation of the tibia on the femur or internal rotation of the femur on the tibia. Past studies have reported that internal rotation of the
characteristics of relative motion (i.e., coordination), which is the goal of the initial stage of learning. Horn, Williams, and Scott ( 2002 ) suggest the primary role of a demonstration is to convey general strategy-related features of a movement. Similarly, Horn, Williams, Hayes, Hodges, and Scott ( 2007