Carol Giuliani

Kinematics and Electromyography of Landing Preparation in Vertical Stop-Jump Risks for Noncontact Anterior Cruciate Ligament Injury

Background Biomechanical analysis of stop-jump tasks has demonstrated gender differences during landing and a potential increase in risk of noncontact anterior cruciate ligament injury for female athletes. Analysis of landing preparation could advance our understanding of neuromuscular control in movement patterns and be applied to the development of prevention strategies for noncontact anterior cruciate ligament injury. Hypothesis There are differences in the lower extremity joint angles and electromyography of male and female recreational athletes during the landing preparation of a stop-jump task. Study Design Controlled laboratory study. Methods Three-dimensional videographic and electromyographic data were collected for 36 recreational athletes (17 men and 19 women) performing vertical stop-jump tasks. Knee and hip angular motion patterns were determined during the flight phase before landing. Results Knee and hip motion patterns and quadriceps and hamstring activation patterns exhibited significant gender differences. Female subjects generally exhibited decreased knee flexion (P = .001), hip flexion (P = .001), hip abduction (P = .001), and hip external rotation (P = .03); increased knee internal rotation (P = .001); and increased quadriceps activation (P = .001) compared with male subjects. Female subjects also exhibited increased hamstring activation before landing but a trend of decreased hamstring activation after landing compared with male subjects (P = .001). Conclusion Lower extremity motion patterns during landing of the stop-jump task are preprogrammed before landing. Female subjects prepared for landing with decreased hip and knee flexion at landing, increased quadriceps activation, and decreased hamstring activation, which may result in increased anterior cruciate ligament loading during the landing of the stop-jump task and the risk for noncontact ACL injury.

The EXCITE trial: attributes of the Wolf Motor Function Test in patients with subacute stroke.

The Wolf Motor Function Test (WMFT) has been used in rehabilitation studies of chronic stroke patients, but until now its psychometric properties have not been evaluated in patients with subacute stroke. Two hundred twenty-nine participants with subacute stroke (3-9 months postinjury) at 7 research sites met inclusion criteria for the EXCITE Trial and were randomized into immediate or delayed (by 1 year) constraint-induced movement therapy treatment. All evaluations were undertaken by assessors standardized in the administration of the WMFT and masked to treatment designation. Participants were also assessed using the Fugl Meyer Motor Assessment (FMA). Delayed group members had measurements repeated 2 weeks following baseline assessment to determine learning or exposure effects. The results demonstrate that the WMFT differentiated higher from lower functioning participants across sites; scores were uninfluenced by hand dominance or affected side. Women exhibited slower performance times than men. The Functional Ability scale (FAS) portion of the WMFT also revealed lower scores among lower functioning participants and women. Minimal changes were observed after repeating the WMFT among delayed group participants 2 weeks later. The FMA revealed similar results when the total group was divided into higher and lower functional levels at its midpoint score of 33. The WMFT discriminates higher from lower functioning participants tested across research sites. Comparable findings using the FMA support the criterion validity of the WMFT.

Physical Activity as a Preventative Factor for Frailty: The Health, Aging, and Body Composition Study

BACKGROUND It is unclear if physical activity (PA) can prevent or reverse frailty. We examined different doses and types of PA and their association with the onset and severity of frailty. METHODS Health, Aging and Body Composition (Health ABC) study participants (N = 2,964) were followed for 5 years, with frailty defined as a gait speed of less than 0.60 m/s and/or inability to rise from a chair without using ones arms. Individuals with one impairment were considered moderately frail and those with both severely frail. We examined PA doses of volume and intensity, activity types (eg, lifestyle vs exercise activities), and their associations with incident frailty and transition to severe frailty in those who became frail. RESULTS Adjusted models indicated that sedentary individuals had significantly increased odds of developing frailty compared with the exercise active group (adjusted odds ratio [OR] = 1.45; 95% confidence interval [CI]: 1.04-2.01), whereas the lifestyle active did not. Number of diagnoses was the strongest predictor of incident frailty. In those who became frail during follow-up (n = 410), there was evidence that the sedentary (adjusted OR = 2.80; 95% CI: 0.98-8.02) and lifestyle active (adjusted OR = 2.81; 95% CI: 1.22-6.43) groups were more likely to have worsening frailty over time. CONCLUSIONS Despite the strong relationship seen between comorbid conditions and onset of frailty, this observational study suggests that participation in self-selected exercise activities is independently associated with delaying the onset and the progression of frailty. Regular exercise should be further examined as a potential factor in frailty prevention for older adults.

Detecting altered postural control after cerebral concussion in athletes with normal postural stability

Objective: To determine if approximate entropy (ApEn), a regularity statistic from non-linear dynamics, could detect changes in postural control during quiet standing in athletes with normal postural stability after cerebral concussion. Methods: The study was a retrospective, case series analysis of centre of pressure (COP) data collected during the Sensory Organization Test (SOT) from NCAA Division I (USA) athletes prior to and within 48 h after injury. Subjects were 21 male and six female athletes from a variety of sports who sustained a cerebral concussion between 1997 and 2003. After injury, athletes displayed normal postural stability equivalent to preseason levels. For comparison, COP data also were collected from 15 male and 15 female healthy non-athletes on two occasions. ApEn values were calculated for COP anterior-posterior (AP) and medial-lateral (ML) time series. Results: Compared to healthy subjects, COP oscillations among athletes generally became more regular (lower ApEn value) after injury despite the absence of postural instability. For AP time series, declines in ApEn values were much larger in SOT conditions 1 and 2 (approximately three times as large as the standard error of the mean) than for all other conditions. For ML time series, ApEn values declined after injury in all sensory conditions (F1,55 = 6.36, p = 0.02). Conclusions: Athletes who demonstrated normal postural stability after concussion nonetheless displayed subtle changes in postural control. Changes in ApEn may have represented a clinically abnormal finding. ApEn analysis of COP oscillations may be a valuable supplement to existing concussion assessment protocols for athletes.

Instruction of jump-landing technique using videotape feedback : Altering lower extremity motion patterns

Background Anterior cruciate ligament injury prevention programs have used videotapes of jump-landing technique as a key instructional component to improve landing performance. Hypothesis All videotape feedback model groups will increase knee flexion angles at initial contact and overall knee flexion motion and decrease peak vertical ground reaction forces and peak proximal anterior tibial shear forces to a greater extent than will a nonfeedback group. The secondary hypothesis is that the videotape feedback using the combination of the expert and self models will create the greatest change in each variable. Study Design Controlled laboratory study. Methods Knee kinematics and kinetics of college-aged recreational athletes randomly placed in 3 different videotape feedback model groups (expert only, self only, combination of expert and self) and a nonfeedback group were collected while participants performed a basketball jump-landing task on 3 testing occasions. Results All feedback groups significantly increased knee angular displacement flexion angles [F(6,70) = 8.03, P =. 001] and decreased peak vertical ground reaction forces [F(6,78) = 2.68, P =. 021] during performance and retention tests. The self and combination groups significantly increased knee angular displacement flexion angles more than the control group did; the expert model group did not change significantly more than the control group did. All feedback groups and the nonfeedback group significantly reduced peak vertical forces across performance and retention tests. There were no statistically significant changes in knee flexion angle at initial ground contact (P =. 111) and peak proximal anterior tibial shear forces (P =. 509) for both testing sessions for each group. Conclusion The use of self or combination videotape feedback is most useful for increasing knee angular displacement flexion angles and reducing peak vertical forces during landing. Clinical Relevance The use of self or combination modeling is more effective than is expert-only modeling for the implementation of instructional programs aimed at reducing the risk of jump-landing anterior cruciate ligament injuries.

Head and shoulder posture affect scapular mechanics and muscle activity in overhead tasks

Forward head and rounded shoulder posture (FHRSP) is theorized to contribute to alterations in scapular kinematics and muscle activity leading to the development of shoulder pain. However, reported differences in scapular kinematics and muscle activity in those with forward head and rounded shoulder posture are confounded by the presence of shoulder pain. Therefore, the purpose of this study was to compare scapular kinematics and muscle activity in individuals free from shoulder pain, with and without FHRSP. Eighty volunteers were classified as having FHRSP or ideal posture. Scapular kinematics were collected concurrently with muscle activity from the upper and lower trapezius as well as the serratus anterior muscles during a loaded flexion and overhead reaching task using an electromagnetic tracking system and surface electromyography. Separate mixed model analyses of variance were used to compare three-dimensional scapular kinematics and muscle activity during the ascending phases of both tasks. Individuals with FHRSP displayed significantly greater scapular internal rotation with less serratus anterior activity, during both tasks as well as greater scapular upward rotation, anterior tilting during the flexion task when compared with the ideal posture group. These results provide support for the clinical hypothesis that FHRSP impacts shoulder mechanics independent of shoulder pain.

Characteristics of stepping over an obstacle in community dwelling older adults under dual-task conditions

Previous research suggests that older adults may have difficulty attending to simultaneous tasks. This study was conducted to determine how concurrent performance of a secondary cognitive task influences walking and stepping over an obstacle in community dwelling older adults. Twenty-one men and women with a mean age of 73.4 years (S.D.=5.3) participated in the study. Subjects performed a gait task both alone (single-task condition) and in combination with a cognitive task that involved reciting numbers (dual-task condition). In the gait task, each subject walked at his/her fastest speed along a 10-m walkway and stepped over an obstacle designed to simulate a door threshold. Paired t-tests were used to compare gait parameters (10 m gait speed, gait speed during obstacle approach and negotiation, medial-lateral center of pressure excursion and velocity during obstacle negotiation, foot clearance over the obstacle, step length and foot position relative to the obstacle) and cognitive task performance under single and dual-task conditions. Toe-obstacle distance was greater and obstacle-heel distance was reduced under dual-task conditions. Performance of the remaining gait parameters did not change with the addition of a secondary cognitive task. Cognitive task performance decreased under dual-task conditions. These community dwelling older adults demonstrated minimal or no change in measured gait parameters during simultaneous performance of a cognitive task. The observed decrement in cognitive task performance suggests that subjects may have placed a higher priority on gait performance.

Intrasession and intersession reliability of handheld dynamometry in children with cerebral palsy.

Purpose. The primary purpose of this study was to determine the intrasession and intersession reliability of isometric force measurements using handheld dynamometry of the knee extensors and flexors and hip abductors in 15 children with cerebral palsy. A secondary purpose was to explore the relationships between muscle forces and standing and walking skills among these subjects. Subjects. Fifteen children with spastic diplegic or quadriplegic cerebral palsy (mean age, 11.7 ± 3.6 years) participated. Methods. Two test sessions were separated by four to 14 days. Isometric force production was measured for three muscle groups bilaterally using a handheld dynamometer. Reliability was measured using the intraclass correlation coefficient (ICC 3,1) and the standard error of measurement. The relationship between muscle force values and standing and walking skills [measured with the Gross Motor Function Measure (GMFM), Dimensions D and E] was examined using Pearson’s correlation coefficient. Results. Except for left knee flexion, the intrasession and intersession ICCs were 0.84 or greater. The standard errors of measurement ranged from 6.72 to 25.26 N. GMFM Dimensions D and E were positively related to normalized hip abductor force. GMFM Dimension E and the sum of Dimensions D + E were positively related to normalized knee flexor force. Conclusion. This group of children with cerebral palsy demonstrated primarily good to high reliability coefficients for isometric force measurements of three lower extremity muscle groups using handheld dynamometry. We suggest that physical therapists use the standard error of measurement for individual clients to help them distinguish measurement error from true changes in muscle force production.

Passive compliance and length of the hamstring muscles of healthy men anc women

This study examined the passive compliance and length of the hamstring muscles of 15 healthy men and 15 healthy women (ages 21-37) with passive straight-leg-raising between 65° and 80°. Subjects were positioned on their left sides with the pelvis stabilized and the right thigh fixed at 90° on a horizontal platform. After three practice trials of maximal passive knee extension, subjects received three trials for data collection. Muscle activity was monitored with surface EMG and passive resistance to knee extension was measured with a dynamometer as the limb was photographed at six force-dependent positions. The passive compliance was computed as the ratio of the change in the knee angle (ΔAngle) to the change in passive torque (ΔTorque), (ΔAngle/ΔTorque). Hamstring muscle lengths were measured simultaneously. An ANovA revealed a difference (P = 0·001) between the passive compliance ratios of the men (1·4 ± 0·-03) and women (2·2 ± 0·08) but not between their initial knee angles or their maximal knee angles. Independent t-tests showed a difference (P < 0·001) between the maximal passive torque of the men (41·4 ± 5·7 Nm) and women (27·4 ± 7·7 Nm). The torques were not different when standardized to body mass. Although ANOVAS showed that the absolute hamstring muscle lengths differed between genders, they were not different when standardized as a percentage of the femur length.

Influence of Hippotherapy on the Kinematics and Functional Performance of Two Children with Cerebral Palsy

Therapists use hippotherapy to improve postural control in children with neuromotor dysfunction. Understanding the influence of the horses movement on the child may clarify mechanisms, which influence posture during hippotherapy. This study was conducted in two phases. First measures of the kinemat