Tummy Time Tracking: Examining Agreement Between Parent Recall and Direct Observation in Infants.

IMPORTANCE: Parent recall is the primary method for measuring positioning practices such as tummy time in infants. Concerns regarding the accuracy of parent recall have been raised in the literature. To date, no study has examined the agreement of tummy time recall measures with gold-standard methods. OBJECTIVE: To assess the agreement between parental recall versus direct observation of tummy time in infants, and to explore the impact of prematurity on this relationship. DESIGN: Cross-sectional observational study, spanning 1 yr. SETTING: Participants' homes Participants: Thirty-two infant-parent dyads (19 full-term, 13 preterm), with infants ages 3 to 6 mo and caregivers ages older than 18 yr. OUTCOME AND MEASURES: Home-recorded videos of infant play across 3 days were used as a proxy for direct observation of tummy time and compared with a 12-item parent recall survey. RESULTS: Parent recall had a significant moderate correlation (ρ = .54, p = .002) with direct observation in full-term infants but was not correlated (p = .23) with direct observation in preterm infants. On average, parents of preterm infants overestimated tummy time by 2.5 times per day compared with direct observation. CONCLUSIONS AND RELEVANCE: For full-term infants, parent recall measures of tummy time exhibit an acceptable level of agreement with direct observation and can be reliably used over shorter periods. Parents of preterm infants may display a bias in recalling tummy time, leading to overestimations. To accurately assess tummy time in this population, a combination of subjective and objective measures should be explored. Plain-Language Summary: Tummy time is an essential movement experience for infants, especially for preterm infants, who are at a higher risk for motor delays. The most common way to track tummy time is through parent reports, or recall, versus a practitioner directly observing tummy time in the home. Despite the widespread use of parent recall to track tummy time, no study has examined the accuracy of parent recall versus direct observation in the home. Accurately assessing tummy time is crucial for improving and supporting health outcomes for infants. This study found that prematurity may affect the accuracy of parent recall for assessing tummy time in young infants. The authors discuss the implications of this finding and provide suggestions to guide the selection of appropriate methods to measure tummy time in clinical practice and research studies.

Skill-Related Adaptive Modifications of Gaze Stabilization in Elite and Non-Elite Athletes.

The vestibular ocular reflex (VOR) provides gaze stability during head movements by driving eye movements in a direction opposing head motion. Although vestibular-based rehabilitation strategies are available, it is still unclear whether VOR can be modulated by training. By examining adaptations in gaze stabilization mechanisms in a population with distinct visuomotor requirements for task success (i.e., gymnasts), this study was designed to determine whether experience level (as a proxy of training potential) was associated with gaze stabilization modifications during fixed target (VOR promoting) and fixed-to-head-movement target (VOR suppressing) tasks. Thirteen gymnasts of different skill levels participated in VOR and VOR suppression tasks. The gain between head and eye movements was calculated and compared between skill levels using an analysis of covariance. Across experience levels, there was a similar degradation in VOR gain away from -1 at higher movement speeds. However, during the suppression tasks, more experienced participants were able to maintain VOR gain closer to 0 across movement speeds, whereas novice participants showed greater variability in task execution regardless of movement speed. Changes in adaptive modifications to gaze stability associated with experience level suggest that the mechanisms impacting gaze stabilization can be manipulated through training.

A Virtual Reality Game Suite for Graded Rehabilitation in Patients With Low Back Pain and a High Fear of Movement: Within-Subject Comparative Study.

BACKGROUND: Complex movement pathologies that are biopsychosocial in nature (eg, back pain) require a multidimensional approach for effective treatment. Virtual reality is a promising tool for rehabilitation, where therapeutic interventions can be gamified to promote and train specific movement behaviors while increasing enjoyment, engagement, and retention. We have previously created virtual reality-based tools to assess and promote lumbar excursion during reaching and functional gameplay tasks by manipulating the position of static and dynamic contact targets. Based on the framework of graded exposure rehabilitation, we have created a new virtual reality therapy aimed to alter movement speed while retaining the movement-promoting features of our other developments. OBJECTIVE: This study aims to compare lumbar flexion excursion and velocity across our previous and newly developed virtual reality tools in a healthy control cohort. METHODS: A total of 31 healthy participants (16 males, 15 females) took part in 3 gamified virtual reality therapies (ie, Reachality, Fishality, and Dodgeality), while whole-body 3D kinematics were collected at 100 Hz using a 14-camera motion capture system. Lumbar excursion, lumbar flexion velocity, and actual target impact location in the anterior and vertical direction were compared across each virtual reality task and between the 4 anthropometrically defined intended target impact locations using separate 2-way repeated measures analysis of variance models. RESULTS: There was an interaction between game and impact height for each outcome (all P<.001). Post-hoc simple effects models revealed that lumbar excursion was reduced during Reachality and Fishality relative to that during Dodgeality for the 2 higher impact heights but was greater during Reachality than during Fishality and Dodgeality for the lowest impact height. Peak lumbar flexion velocity was greater during Dodgeality than during Fishality and Reachality across heights. Actual target impact locations during Dodgeality and Fishality were lower relative to those during Reachality at higher intended impact locations but higher at lower intended impact locations. Finally, actual target impact location was further in the anterior direction for Reachality compared to that for Fishality and for Fishality relative to that for Dodgeality. CONCLUSIONS: Lumbar flexion velocity was reduced during Fishality relative to that during Dodgeality and resembled velocity demands more similar to those for a self-paced reaching task (ie, Reachality). Additionally, lumbar motion and target impact location during Fishality were more similar to those during Reachality than to those during Dodgeality, which suggests that this new virtual reality game is an effective tool for shaping movement. These findings are encouraging for future research aimed at developing an individualized and graded virtual reality intervention for patients with low back pain and a high fear of movement.

Distinguishing chronic low back pain in young adults with mild to moderate pain and disability using trunk compliance.

Chronic low back pain (cLBP) rates among younger individuals are rising. Although pain and disability are often less severe, underlying changes in trunk behavior may be responsible for recurrence. We examine the biomarker capacity of a simple Trunk Compliance Index (TCI) to distinguish individuals with and without cLBP. A random subset (n = 49) of the RELIEF RCT were matched to healthy controls for sex, age, height and weight. We measured TCI (as displacement/ weight-normalized perturbation force) using anthropometrically-matched, suddenly-applied pulling perturbations to the trunk segment, randomized across three planes of motion (antero-posterior, medio-lateral, and rotational). Mean differences between cLBP, sex and perturbation direction were assessed with repeated-measures analysis of variance. Discriminatory accuracy of TCI was assessed using Receiver Operator Characteristic (ROC) analysis. Baseline characteristics between groups were equivalent (x̅ [range]): sex (57% female / group), age (23.0 [18-45], 22.8 [18-45]), height, cm (173.0 [156.5-205], 171.3 [121.2-197], weight, kg (71.8 [44.5-116.6], 71.7 [46.8-117.5]) with cLBP associated with significantly lower TCI for 5 of 6 directions (range mean difference, - 5.35: - 1.49, range 95% CI [- 6.46: - 2.18 to - 4.35: - 0.30]. Classification via ROC showed that composite TCI had high discriminatory potential (area under curve [95% CI], 0.90 [0.84-0.96]), driven by TCI from antero-posterior perturbations (area under curve [95% CI], 0.99 [0.97-1.00]). Consistent reductions in TCI suggests global changes in trunk mechanics that may go undetected in classic clinical examination. Evaluation of TCI in younger adults with mild pain and disability may serve as a biomarker for chronicity, leading to improved preventative measures in cLBP.Trial Registration and Funding RELIEF is registered with clinicaltrials.gov (NCT01854892) and funded by the NIH National Center for Complementary & Integrative Health (R01AT006978).

Agreement Analysis between Vive and Vicon Systems to Monitor Lumbar Postural Changes.

Immersive virtual reality has recently developed into a readily available system that allows for full-body tracking. Can this affordable system be used for component tracking to advance or replace expensive kinematic systems for motion analysis in the clinic? The aim of this study was to assess the accuracy of position and orientation measures from Vive wireless body trackers when compared to Vicon optoelectronic tracked markers attached to (1) a robot simulating trunk flexion and rotation by repeatedly moving to know locations, and (2) healthy adults playing virtual reality games necessitating significant trunk displacements. The comparison of both systems showed component tracking with Vive trackers is accurate within 0.68 ± 0.32 cm translationally and 1.64 ± 0.18° rotationally when compared with a three-dimensional motion capture system. No significant differences between Vive trackers and Vicon systems were found suggesting the Vive wireless sensors can be used to accurately track joint motion for clinical and research data.

A Motor Learning Paradigm Combining Technology and Associative Learning to Assess Prone Motor Learning in Infants.

BACKGROUND: Associative learning is the ability to discover a relationship between two or more events. We combined principles of learning and technology to develop a paradigm to assess associative learning in prone. PURPOSE: The purpose of this study was to determine whether 3- to 6-month-old infants can demonstrate: (1) short-term learning of an association between their upper body movements in prone and activation of a toy, and (2) retention of the association learned on day 1, 24 hours later. METHODS: Twenty-eight infants who were 3 to 6 months of age and who were typically developing were tested for 2 consecutive days in an instrumented play gym. Both days of testing had a baseline and 4 acquisition phases (2 minutes each). During the acquisition phase, the toy activated for a maximum of 10 seconds when the infant's head was above a threshold. A criterion was set a priori to distinguish infants as short-term learners and retainers of the association learned on day 1. RESULTS: Of 28 infants, 22 and 14 infants completed all phases of the testing on day 1 and day 2, respectively. Fourteen (50%) of the infants met the criteria for short-term learners. On day 2, there was an analyzable sample of 9 short-term learners. Three of the 12 short-term learners (25%) demonstrated retention on day 2. CONCLUSION: Consistent with prior infant motor learning research, half of the infants demonstrated associative learning in this novel assessment in prone; however, based on study criteria, the infants had limited retention of the association on day 2.

The Geek Perspective: Answering the Call for Advanced Technology in Research Inquiry Related to Pediatric Brain Injury and Motor Disability.

The Academy of Pediatric Physical Therapy Research Summit IV issued a Call to Action for community-wide intensification of a research enterprise in inquiries related to pediatric brain injury and motor disability by way of technological integration. But the barriers can seem high, and the pathways to integrative clinical research can seem poorly marked. Here, we answer the Call by providing framework to 3 objectives: (1) instrumentation, (2) biometrics and study design, and (3) data analytics. We identify emergent cases where this Call has been answered and advocate for others to echo the Call both in highly visible physical therapy venues and in forums where the audience is diverse.

Effects of Real-World Versus Virtual Environments on Joint Excursions in Full-Body Reaching Tasks.

Starting from an upright standing posture and reaching for a target that requires some forward bending of the trunk can involve many different configurations of the trunk and limb segments. We sought to determine if configurations of the limb and trunk segments during our standardized full-body reaching tasks were influenced by the visual environment. This paper examined movement patterns of healthy participants ([Formula: see text], eight female and nine male) performing full body reaching tasks to: 1) real-world targets; 2) virtual targets presented on a 3-D television; and 3) virtual targets presented using a head-mounted display. For reaches performed in the virtual world, the avatar was presented from a third-person perspective for the 3-D television and from a first-person perspective for the head-mounted display. Reaches to virtual targets resulted in significantly greater excursions of the ankle, knee, hip, spine, and shoulder compared with reaches made to real-world targets. This resulted in significant differences in the forward and downward displacements of the whole-body center of mass between the visual environments. Visual environment clearly influences how subjects perform full-body reaching tasks to static targets. Because a primary goal of virtual reality within rehabilitation is often to restore movement following orthopedic or neurologic injury, it is important to understand how visual environment will affect motor behavior. The present findings suggest that the existing game systems that track and present avatars from a third-person perspective elicit significantly different motor behavior when compared with the same tasks being presented from a first-person perspective.

Effects of Visual Display on Joint Excursions Used to Play Virtual Dodgeball.

BACKGROUND: Virtual reality (VR) interventions hold great potential for rehabilitation as commercial systems are becoming more affordable and can be easily applied to both clinical and home settings. OBJECTIVE: In this study, we sought to determine how differences in the VR display type can influence motor behavior, cognitive load, and participant engagement. METHODS: Movement patterns of 17 healthy young adults (8 female, 9 male) were examined during games of Virtual Dodgeball presented on a three-dimensional television (3DTV) and a head-mounted display (HMD). The participant's avatar was presented from a third-person perspective on a 3DTV and from a first-person perspective on an HMD. RESULTS: Examination of motor behavior revealed significantly greater excursions of the knee (P=.003), hip (P<.001), spine (P<.001), shoulder (P=.001), and elbow (P=.026) during HMD versus 3DTV gameplay, resulting in significant differences in forward (P=.003) and downward (P<.001) displacement of the whole-body center of mass. Analyses of cognitive load and engagement revealed that relative to 3DTV, participants indicated that HMD gameplay resulted in greater satisfaction with overall performance and was less frustrating (P<.001). There were no significant differences noted for mental demand. CONCLUSIONS: Differences in visual display type and participant perspective influence how participants perform in Virtual Dodgeball. Because VR use within rehabilitation settings is often designed to help restore movement following orthopedic or neurologic injury, these findings provide an important caveat regarding the need to consider the potential influence of presentation format and perspective on motor behavior.

Anxiety's Effect on Muscle Activation and Fatigue in Trumpet Players: A Pilot Study.

Due to the high percentage of musicians who suffer from musculoskeletal disorders, there is a need for more research in the field of music and medicine. The purpose of this study was to analyze the possible relationship between anxiety, muscle activation, and muscle fatigue in undergraduate trumpet players. Assessment tools included surface electromyography (sEMG) data, State Trait Anxiety Inventory (STAI), and Visual Analogue Scales (VAS) of perceived anxiety. Data were collected from 27 undergraduate music students across five universities (22 males, 5 females) aged 18 to 24 years. The three muscles targeted by the sEMG were the upper trapezius, sternocleidomastoid, and masseter muscles. Participants were randomly divided into two single-blinded groups: (1) anxiety-induction and (2) control. The anxiety-induction group was instructed to play as accurately as possible and informed that mistakes were being counted and evaluated, while the control group was instructed to play without any concern for possible mistakes. The anxiety-induction group was shown to have more masseter muscle activation than the control; the anxiety-induction group also displayed a higher fatigue rate in all three muscles versus the controls. Subjects with high perceived-anxiety (as measured by VAS) displayed higher masseter activation and higher fatigue rates in the upper trapezius and sternocleidomastoid than non-anxious participants. Despite these notable trends, there was no statistical significance for any of the muscle groups for muscle activation or fatigue.

Thoracic Spine Manipulation in Individuals With Subacromial Impingement Syndrome Does Not Immediately Alter Thoracic Spine Kinematics, Thoracic Excursion, or Scapular Kinematics: A Randomized Controlled Trial.

STUDY DESIGN: Randomized controlled trial. OBJECTIVES: To determine if thoracic spinal manipulative therapy (SMT) alters thoracic kinematics, thoracic excursion, and scapular kinematics compared to a sham SMT in individuals with subacromial impingement syndrome, and also to compare changes in patient-reported outcomes between treatment groups. BACKGROUND: Prior studies indicate that thoracic SMT can improve pain and disability in individuals with subacromial impingment syndrome. However, the mechanisms underlying these benefits are not well understood. METHODS: Participants with shoulder impingement symptoms (n = 52) were randomly assigned to receive a single session of thoracic SMT or sham SMT. Thoracic and scapular kinematics during active arm elevation and overall thoracic excursion were measured before and after the intervention. Patient-reported outcomes measured were pain (numeric pain-rating scale), function (Penn Shoulder Score), and global rating of change. RESULTS: Following the intervention, there were no significant differences in changes between groups for thoracic kinematics or excursion, scapular kinematics, and patient-reported outcomes (P>.05). Both groups showed an increase in scapular internal rotation during arm raising (mean, 0.9°; 95% confidence interval [CI]: 0.3°, 1.6°; P = .003) and lowering (0.8°; 95% CI: 0.0°, 1.5°; P = .041), as well as improved pain reported on the numeric pain-rating scale (1.2 points; 95% CI: 0.3, 1.8; P<.001) and function on the Penn Shoulder Score (9.1 points; 95% CI: 6.5, 11.7; P<.001). CONCLUSION: Thoracic spine extension and excursion did not change significantly following thoracic SMT. There were small but likely not clinically meaningful changes in scapular internal rotation in both groups. Patient-reported pain and function improved in both groups; however, there were no significant differences in the changes between the SMT and the sham SMT groups. Overall, patient-reported outcomes improved in both groups without meaningful changes to thoracic or scapular motion. LEVEL OF EVIDENCE: Therapy, level 1b-.

Immediate changes in pressure pain sensitivity after thoracic spinal manipulative therapy in patients with subacromial impingement syndrome: A randomized controlled study.

BACKGROUND: Thoracic SMT can improve symptoms in patients with subacromial impingement syndrome. However, at this time the mechanisms of SMT are not well established. It is possible that changes in pain sensitivity may occur following SMT. OBJECTIVES: To assess the immediate pain response in patients with shoulder pain following thoracic spinal manipulative therapy (SMT) using pressure pain threshold (PPT), and to assess the relationship of change in pain sensitivity to patient-rated outcomes of pain and function following treatment. DESIGN: Randomized Controlled Study. METHODS: Subjects with unilateral subacromial impingement syndrome (n = 45) were randomly assigned to receive treatment with thoracic SMT or sham thoracic SMT. PPT was measured at the painful shoulder (deltoid) and unaffected regions (contralateral deltoid and bilateral lower trapezius areas) immediately pre- and post-treatment. Patient-rated outcomes were pain (numeric pain rating scale - NPRS), function (Pennsylvania Shoulder Score - Penn), and global rating of change (GROC). RESULTS: There were no significant differences between groups in pre-to post-treatment changes in PPT (p ≥ 0.583) nor were there significant changes in PPT within either group (p ≥ 0.372) following treatment. NPRS, Penn and GROC improved across both groups (p < 0.001), but there were no differences between the groups (p ≥ 0.574). CONCLUSION: There were no differences in pressure pain sensitivity between participants receiving thoracic SMT versus sham thoracic SMT. Both groups had improved patient-rated pain and function within 24-48 h of treatment, but there was no difference in outcomes between the groups.

A novel myoelectric training device for upper limb prostheses.

A training system intended for myoelectric prosthetic hands for upper limb amputees was developed to assist in learning myoelectric control schemes and training muscle isolation. The trainer allowed a user to operate a remote controlled car by use of a control scheme commonly used in myoelectric prosthetic hands. The trainer was designed to be easy for therapists to use and more engaging for the user than current methods of signal training. Preliminary testing of the trainer was conducted with eight nonamputee adult volunteers. The results indicated that the trainer could be a useful tool for myoelectric training in upper limb amputees. All subjects' skill with the myoelectric control scheme improved over the course of testing, with the improvements being greater at the beginning of the training period than at the end. Whereas the individual subjects' performance varied greatly at the beginning of the training, the subjects had achieved a more uniform level of performance by the end of the training, approaching the minimum possible values for the assessments.

Postural-stability tests that identify individuals with chronic ankle instability.

CONTEXT: Chronic ankle instability (CAI) is characterized by repeated ankle sprains, which have been linked to postural instability. Therefore, it is important for clinicians to identify individuals with CAI who can benefit from rehabilitation. OBJECTIVE: To assess the likelihood that CAI participants will exhibit impaired postural stability and that healthy control participants will exhibit better test performance values. DESIGN: Case-control study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: People with CAI (n = 17, age = 23 ± 4 years, height = 168 ± 9 cm, weight = 68 ± 12 kg) who reported ankle "giving-way" sensations and healthy volunteers (n = 17, age = 23 ± 3 years, height = 168 ± 8 cm, weight = 66 ± 12 kg). INTERVENTION(S): Participants performed 7 balance tests: Balance Error Scoring System (BESS), time in balance, foot lift, single-legged stance on a force plate, Star Excursion Balance Test, side hop, and figure-of-8 hop. MAIN OUTCOME MEASURE(S): Balance was quantified with errors (score) for the BESS, length of time balancing (seconds) for time-in-balance test, frequency of foot lifts (score) for foot-lift test, velocity (cm/s) for all center-of-pressure velocity measures, excursion (cm) for center-of-pressure excursion measures, area (cm2) for 95% confidence ellipse center-of-pressure area and center-of-pressure rectangular area, time (seconds) for anterior-posterior and medial-lateral time-to-boundary (TTB) measures, distance reached (cm) for Star Excursion Balance Test, and time (seconds) to complete side-hop and figure-of-8 hop tests. We calculated area-under-the-curve values and cutoff scores and used the odds ratio to determine if those with and without CAI could be distinguished using cutoff scores. RESULTS: We found significant area-under-the-curve values for 4 static noninstrumented measures, 3 force-plate measures, and 3 functional measures. Significant cutoff scores were noted for the time-in-balance test (≤25.89 seconds), foot-lift test (≥5), single-legged stance on the firm surface (≥3 errors) and total (≥14 errors) on the BESS, center-of-pressure resultant velocity (≥1.56 cm/s), standard deviations for medial-lateral (≤1.56 seconds) time-to-boundary and anterior-posterior (≤3.78 seconds) time-to-boundary test, posteromedial direction on the Star Excursion Balance Test (≤0.91), side-hop test (≥12.88 seconds), and figure-of-8 hop test (≥17.36 seconds). CONCLUSIONS: Clinicians can use any of the 10 significant measures with their associated cutoff scores to identify those who could benefit from rehabilitation that reestablishes postural stability.

Clinical examination results in individuals with functional ankle instability and ankle-sprain copers.

CONTEXT: Why some individuals with ankle sprains develop functional ankle instability and others do not (ie, copers) is unknown. Current understanding of the clinical profile of copers is limited. OBJECTIVE: To contrast individuals with functional ankle instability (FAI), copers, and uninjured individuals on both self-reported variables and clinical examination findings. DESIGN: Cross-sectional study. SETTING: Sports medicine research laboratory. PATIENTS OR OTHER PARTICIPANTS: Participants consisted of 23 individuals with a history of 1 or more ankle sprains and at least 2 episodes of giving way in the past year (FAI: Cumberland Ankle Instability Tool [CAIT] score = 20.52 ± 2.94, episodes of giving way = 5.8 ± 8.4 per month), 23 individuals with a history of a single ankle sprain and no subsequent episodes of instability (copers: CAIT score = 27.74 ± 1.69), and 23 individuals with no history of ankle sprain and no instability (uninjured: CAIT score = 28.78 ± 1.78). INTERVENTION(S): Self-reported disability was recorded using the CAIT and Foot and Ankle Ability Measure for Activities of Daily Living and for Sports. On clinical examination, ligamentous laxity and tenderness, range of motion (ROM), and pain at end ROM were recorded. MAIN OUTCOME MEASURE(S): Questionnaire scores for the CAIT, Foot and Ankle Ability Measure for Activities of Daily Living and for Sports, ankle inversion and anterior drawer laxity scores, pain with palpation of the lateral ligaments, ankle ROM, and pain at end ROM. RESULTS: Individuals with FAI had greater self-reported disability for all measures (P < .05). On clinical examination, individuals with FAI were more likely to have greater talar tilt laxity, pain with inversion, and limited sagittal-plane ROM than copers (P < .05). CONCLUSIONS: Differences in both self-reported disability and clinical examination variables distinguished individuals with FAI from copers at least 1 year after injury. Whether the deficits could be detected immediately postinjury to prospectively identify potential copers is unknown.

Botulinum toxin type A for nonsurgical lateral release in patellofemoral pain syndrome: a case study.

SETTING: Outpatient rehabilitation clinic. PATIENT: A 37-year-old physically active male. CASE DESCRIPTION: The patient presented with anterior left knee pain, exacerbated when climbing stairs, sitting, and running. Exam showed lateral tracking patellae and palpable crepitus. One hundred fifty units of botulinum toxin A was injected into his left vastus lateralis. He underwent a 12-week home exercise program targeting the vastus medialis (VM). ASSESSMENT/RESULTS: Visual analog scale decreased from 70 to 0 on a 150-mm scale, from initial until 8 weeks postinjection. Functional Index Questionnaire increased from 5 to 16 over the same period. Knee torque and surface electromyography findings showed increased activity of the VM during knee extension. CONCLUSION: Botulinum injection into the vastus lateralis in conjunction with VM strengthening may provide more effective treatment of patellofemoral pain syndrome. Further study is needed to explore this novel treatment of patellofemoral pain syndrome.

The role of head-in-space stability on stepping reactions in young and elderly adults.

This study compared head kinematic responses and step latency following an anteriorly directed postural perturbation between two groups (Young, mean age 27.39; Elderly, mean age 71.9). We further attempted to demonstrate, for the first time, a positive linear relationship between sagittal plane head angular velocities and stepping responses in both groups. It was hypothesized that the Elderly would demonstrate higher head angular velocities and greater step latencies than the Young. We also hypothesized that a positive linear relationship would show that, following a perturbation, trials where head angular velocity was low yielded quicker step responses. Each participant experienced three perturbations under five different visual conditions designed to alter visual input and head/trunk coordination. Repeated-measures ANOVA was used, with α set at 0.05. For each test condition, the Elderly consistently demonstrated longer step latencies while exhibiting higher head angular velocities. For each group, a positive linear relationship was shown between the two dependent variables (Young: r=0.86; Elderly, r=0.84). During a postural perturbation, as head angular velocity increased, stepping responses were delayed.

Repeatability of the modified Oxford foot model during gait in healthy adults.

BACKGROUND: The Oxford foot model (OFM) is a multi-segment model for calculating hindfoot and forefoot motion. Limited information is available regarding the repeatability and error of this model in adults. Therefore the purpose of this study was to assess the intra-tester reliability of OFM hindfoot and forefoot gait kinematics in adults at initial contact (IC) and toe-off (TO). METHODS: Seventeen healthy adults (age=25.1±4.8 years, height=1.75±0.10m, weight=74.0±12.4kg) were tested on a single visit, during which 1 examiner recorded 2 sessions. For each session, 10 walking trials were recorded using a 12-camera motion analysis system (Vicon, Oxford, UK). Markers were removed and re-applied between sessions. Dynamic hindfoot and forefoot angles were calculated both with and without referencing to neutral stance (assuming neutral stance angles are zero in all planes). Using the 10 trial average, intraclass correlation coefficients (ICC(2,k)) and standard errors of the measurement were calculated for each reference condition, anatomical plane, and joint (hindfoot, forefoot). RESULTS: Referencing to neutral stance resulted in good reliability (ICC≥0.83) and small error (≤2.45°) for hindfoot and forefoot angle in all planes. Without referencing to neutral stance, sagittal and transverse plane reliability were also good (ICC≥0.90) and error small (≤3.14°); however, frontal plane reliability was poor (ICC≤0.77), with large error (≥4.86°). DISCUSSION: Our results show that overall the OFM is reliable during adult gait. Reliability for adults is higher than previously reported in children. Referencing joint angles to neutral stance decreased error by up to 2° from previous reports.