Donna Moxley Scarborough

Quadriceps muscle strength and dynamic stability in elderly persons

Several measures of dynamic stability during two functional activities correlated to quadriceps femoris muscle strength. A total of 34 disabled elders (aged 60-88) living in the Boston area consented to maximum isometric quadriceps muscle strength testing, chair rise and gait analysis. During chair rise, quadriceps strength significantly correlated with maximum upper body vertical linear momentum, r=0.53, P<0.005, anterior posterior linear momentum, r=0. 38, P<0.05, and the time to complete the chair rise, r=-0.48, P<0.05, n=29. Stride length and gait velocity correlated (r=0.56, P<0.001 and r=0.51, P<0.002, n=34) with quadriceps muscle strength. The maximum range of whole body anteroposterior (A/P) linear momentum during gait also correlated with quadriceps strength (r=0.47, P=0. 004, n=31). Dynamic stability during chair rise and gait, at preferred speed, correlates directly with quadriceps femoris muscle strength in functionally limited elderly individuals. In our sample, elders performed one of three movement strategies to arise from a chair, and quadriceps strength did not statistically differ between the chair rise strategy groups. However, persons with the greatest quadriceps strength values were more stable regardless of which chair rise strategy they performed. Our data indicate that clinicians should not suggest that patients use compensatory momentum inducing locomotor strategies unless the patient has sufficient strength to control these induced forces.

Functional vs. strength training in disabled elderly outpatients.

Krebs DE, Scarborough DM, McGibbon CA: Functional vs. strength training in disabled elderly outpatients. Am J Phys Med Rehabil 2007;86:93–103. Objective:To determine whether high-intensity functional training (FT) or strength training (ST) better enables impairment, disability, and functional gains among disabled community-dwelling elders. Design:Randomized, blinded, prospective clinical trial in a large, tertiary care outpatient rehabilitation department. Fifteen elders (62–85 yrs old) referred for physical therapy with one or more impairments, including lower-limb arthritis, participated in 6 wks of FT (weekly outpatient and three to five times per week of home practice in rapid and correct execution of locomotor activities of daily living, including gait, stepping, and sit to stand) or progressive resistive ST using elastic bands with intensity, therapist contact, and home practice similar to those of FT. Results:Both groups significantly improved their combined lower-extremity strength (hip abduction, ankle dorsiflexion, knee flexion, ankle plantarflexion, and knee extension) (P = 0.003), but no statistical difference between the ST and FT group gains (P = 0.203) was found. Subjects in both interventions improved their gait speed, but the FT group improved more than the ST group (P = 0.001). During chair rise, the FT group improved their maximum knee torque more than the ST group (P = 0.033), indicating that they employed a more controlled and efficient movement strategy. Conclusions:These data suggest that an intensive FT intervention results in strength improvements of comparable magnitude as those attained from ST and that FT also confers greater improvements in dynamic balance control and coordination while performing daily life tasks.

Can Tai Chi improve vestibulopathic postural control

OBJECTIVES To evaluate the rationale and scientific support for Tai Chi as an intervention for vestibulopathy and to offer recommendations for future studies. DATA SOURCES A computer-aided search, including MEDLINE and Science Citation Index, to identify original Tai Chi studies published in English; relevant references cited in the retrieved articles were also included. STUDY SELECTION A preliminary screening selected all randomized controlled trials (RCTs), non-RCTs, case-control studies, and case series that included Tai Chi as an intervention and had at least 1 outcome variable relevant to postural stability. DATA EXTRACTION Authors critically reviewed studies and summarized study designs and outcomes in a summary table. DATA SYNTHESIS Twenty-four Tai Chi studies met screening criteria. No studies specifically studying Tai Chi for vestibulopathy were found. Collectively, the 24 studies provide sometimes contradictory but generally supportive evidence that Tai Chi may have beneficial effects for balance and postural impairments, especially those associated with aging. Ten RCTs were found, of which 8 provide support that Tai Chi practiced alone, or in combination with other therapies, can reduce risk of falls, and/or impact factors associated with postural control, including improved balance and dynamic stability, increased musculoskeletal strength and flexibility, improved performance of activities of daily living (ADLs), reduced fear of falling, and general improvement in psychologic well-being. Studies using other designs support the results observed in RCTs. CONCLUSIONS At present, few data exist to support the contention that Tai Chi specifically targets the impairments, functional limitations, disability, and quality of life associated with peripheral vestibulopathy. There are, however, compelling reasons to further investigate Tai Chi for vestibulopathy, in part because Tai Chi appears useful for a variety of nonvestibulopathy etiologic balance disorders, and is safe. Especially needed are studies that integrate measures of balance relevant to ADLs with other psychologic and cognitive measures; these might help identify specific mechanisms whereby Tai Chi can remedy balance disorders.

Tai Chi and vestibular rehabilitation improve vestibulopathic gait via different neuromuscular mechanisms: Preliminary report

BackgroundVestibular rehabilitation (VR) is a well-accepted exercise program intended to remedy balance impairment caused by damage to the peripheral vestibular system. Alternative therapies, such as Tai Chi (TC), have recently gained popularity as a treatment for balance impairment. Although VR and TC can benefit people with vestibulopathy, the degree to which gait improvements may be related to neuromuscular adaptations of the lower extremities for the two different therapies are unknown.MethodsWe examined the relationship between lower extremity neuromuscular function and trunk control in 36 older adults with vestibulopathy, randomized to 10 weeks of either VR or TC exercise. Time-distance measures (gait speed, step length, stance duration and step width), lower extremity sagittal plane mechanical energy expenditures (MEE), and trunk sagittal and frontal plane kinematics (peak and range of linear and angular velocity), were measured.ResultsAlthough gait time-distance measures were improved in both groups following treatment, no significant between-groups differences were observed for the MEE and trunk kinematic measures. Significant within groups changes, however, were observed. The TC group significantly increased ankle MEE contribution and decreased hip MEE contribution to total leg MEE, while no significant changes were found within the VR group. The TC group exhibited a positive relationship between change in leg MEE and change in trunk velocity peak and range, while the VR group exhibited a negative relationship.ConclusionGait function improved in both groups consistent with expectations of the interventions. Differences in each groups response to therapy appear to suggest that improved gait function may be due to different neuromuscular adaptations resulting from the different interventions. The TC groups improvements were associated with reorganized lower extremity neuromuscular patterns, which appear to promote a faster gait and reduced excessive hip compensation. The VR groups improvements, however, were not the result of lower extremity neuromuscular pattern changes. Lower-extremity MEE increases corresponded to attenuated forward trunk linear and angular movement in the VR group, suggesting better control of upper body motion to minimize loss of balance. These data support a growing body of evidence that Tai Chi may be a valuable complementary treatment for vestibular disorders.

Vestibulopathy and Age Effects on Head Stability During Chair Rise

It is unknown how vestibular dysfunction and age differentially affect balance control during functional activities. The objective of this study was to gain insight into the effects of age and vestibulopathy on head control when rising from a chair. Head relative to trunk (head-on-trunk) sagittal plane angular and linear control strategies were studied in patients with bilateral vestibular hypofunction (BVH) and in healthy subjects aged 30-80 years. A two-way analysis of variance was used to compare head-on-trunk kinematics by age (young vs elderly) and diagnosis (healthy vs BVH) at the time of liftoff from the seat. Angular control strategies differed with age but not diagnosis: young (healthy and BVH) subjects stabilized head rotations in space while elderly (healthy and BVH) subjects stabilized head rotations on the trunk. In contrast, linear control strategies differed by diagnosis but not age: BVH subjects (young and old) allowed a greater rate of head-on-trunk translation while healthy subjects (young and old) inhibited such translations. Young BVH subjects stabilized head-in-space rotations (as did young healthy subjects) without a functioning vestibular system, suggesting cervicocollic reflex and/or other sensory compensation for vestibular loss. Elderly BVH subjects stabilized head rotation with respect to the trunk, as did healthy elders, but did not stabilize head-on-trunk translations, suggesting a reliance on passive mechanical responses of the neck to sense head movements. We conclude that compensation strategies used by patients with vestibulopathy are age-dependent and appear to be more tractable in the younger BVH patient.It is unknown how vestibular dysfunction and age differentially affect balance control during functional activities. The objective of this study was to gain insight into the effects of age and vestibulopathy on head control when rising from a chair. Head relative to trunk (head-on-trunk) sagittal plane angular and linear control strategies were studied in patients with bilateral vestibular hypofunction (BVH) and in healthy subjects aged 30-80 years. A two-way analysis of variance was used to compare head-on-trunk kinematics by age (young vs elderly) and diagnosis (healthy vs BVH) at the time of liftoff from the seat. Angular control strategies differed with age but not diagnosis: young (healthy and BVH) subjects stabilized head rotations in space while elderly (healthy and BVH) subjects stabilized head rotations on the trunk. In contrast, linear control strategies differed by diagnosis but not age: BVH subjects (young and old) allowed a greater rate of head-on-trunk translation while healthy subjects (young and old) inhibited such translations. Young BVH subjects stabilized head-in-space rotations (as did young healthy subjects) without a functioning vestibular system, suggesting cervicocollic reflex and:or other sensory compensation for vestibular loss. Elderly BVH subjects stabilized head rotation with respect to the trunk, as did healthy elders, but did not stabilize head-on-trunk translations, suggesting a reliance on passive mechanical responses of the neck to sense head movements. We conclude that compensation strategies used by patients with vestibulopathy are age-dependent and appear to be more tractable in the younger BVH patient.

Athletic Assistive Technology for Persons with Physical Conditions Affecting Mobility

ABSTRACT Recent advances in technology have allowed athletes with physical conditions to perform at increasingly high levels. After the ruling that one such athlete had an advantage over “able-bodied” athletes before the 2008 Olympics, many question whether these technological advances have even augmented athletic abilities. Although much progress has been achieved, technology for “disabled” athletes must be far advanced to allow them to reach and surpass the ability level of able-bodied athletes. Here, we review the current state of assistive devices created to assist athletes with physical conditions affecting their mobility. We form a quantitative comparison between athletes with and without physical conditions, lay out recent advancements in the development of sports-related assistive devices, and discuss the implications of these devices. Using the Paralympics as a guide, this work serves as an overview of the current state of assistive technology for athletes with mobility conditions and a tool for future researchers attempting to bridge the gap between athletes with and without physical conditions.

Injuries observed in a prospective transition from traditional to minimalist footwear: correlation of high impact transient forces and lower injury severity

ABSTRACT Objectives: Minimalist running is increasing in popularity based upon a concept that it can reduce impact forces and decrease injury rates. The purpose of this investigation is to identify the rate and severity of injuries in runners transitioning from traditional to minimalist footwear. The secondary aims were to identify factors correlated with injuries. Methods: Fourteen habitually shod (traditional running shoes) participants were enrolled for this prospective study investigating injury prevalence during transition from traditional running shoes to 5-toed minimalist shoes. Participants were uninjured, aged between 22-41 years, and ran at least twenty kilometers per week in traditional running shoes. Participants were given industry recommended guidelines for transition to minimalist footwear and fit with a 5-toed minimalist running shoe. They completed weekly logs for identification of injury, pain using Visual Analogue Scale (VAS), injury location, and severity. Foot strike pattern and impact forces were collected using 3D motion analysis at baseline, 4 weeks, and 12 weeks. Injuries were scored according to a modified Running Injury Severity Score (RISS). Results: Fourteen runners completed weekly training and injury logs over an average of 30 weeks. Twelve of 14 (86%) runners sustained injuries. Average injury onset was 6 weeks (range 1–27 weeks). Average weekly mileage of 23.9 miles/week prior to transition declined to 18.3 miles/week after the transition. The magnitude of the baseline impact transient peak in traditional shoes and in minimalist shoes negatively correlated with RISS scores (r = −0.45, p = 0.055 and r = −0.53, p = 0.026, respectively). Conclusion: High injury rates occurred during the transition from traditional to minimalist footwear. Non-compliance to transition guidelines and high injury rates suggest the need for improved education. High impact transient forces unexpectedly predicted lower modified RISS scores in this population.

Kinematic sequence patterns in the overhead baseball pitch

ABSTRACT Conceptually, an efficient baseball pitch demonstrates a proximal-to-distal transfer of segmental angular velocity. Such a timing pattern (or kinematic sequence) reduces stress on musculoskeletal structures of the throwing arm and maximises ball velocity. We evaluated the variability of kinematic sequences in 208 baseball pitches. 3D biomechanical pitch analyses were performed on 8–10 fastball pitches from 22 baseball pitchers (5 high school, 11 collegiate and 6 professional). The kinematic sequence patterns – time of peak angular velocity of five body segments: pelvis, trunk, arm, forearm and hand – were measured. None of the pitches analysed demonstrated an entirely proximal-to-distal kinematic sequence. Fourteen different kinematic sequence patterns were demonstrated, with the most prevalent sequence being pelvis → trunk → arm → hand → forearm. Fewer than 10% of the pitchers performed only one kinematic sequence pattern across the sampled pitches. The variability of the kinematic sequence was similar in high-school pitchers and professionals. Previous studies report that deviation from the proximal-to-distal kinematic sequence is associated with increased injury risk. As a method of evaluating the efficient transfer of energy to the hand, the kinematic sequence may provide insight to injury risk in the future. The ideal kinematic sequence and ideal variability of the sequence when throwing have yet to be determined.

The relationship of elbow alignment and kinematics on shoulder torque during the softball pitch: a biomechanical analysis of female softball pitchers

BACKGROUND Female softball pitchers commonly throw more pitches per game and season than their baseball counterparts. The greatest stress to the shoulder during a softball windmill pitch is at ball release (BR). This study investigated shoulder torques at BR among female softball pitchers and identified relationships to the kinematics of the elbow and forearm and alignment of the elbow (carrying angle and elbow extension). METHODS High-speed 3-dimensional biomechanical analyses were performed in 33 pitchers (25 high school, 8 collegiate). Elbow and shoulder biomechanics at BR during fastball pitches and goniometric measures of carrying angle and elbow extension were collected and analyzed. RESULTS Carrying angle correlated positively with shoulder extension torque at BR (rs = 0.371, P = .048) and forearm pronation at BR (rs = 0.370, P = .048). During the windmill pitch, the greater the elbow flexion, the greater shoulder adduction torque at BR (rs = -0.522, P = .007). Multiple regression analysis revealed that the carrying angle, passive elbow extension, and elbow flexion/extension angle at BR predicted shoulder flexion/extension torque at BR (F3,24 = 3.463, R2 = .302, P = .032.) CONCLUSIONS: Our findings demonstrate that shoulder torques during the softball fastpitch are influenced by the carrying angle and the kinematic elbow flexion angle at BR. Sports medicine clinicians and coaches should consider the role that the elbow carrying angle plays in creating shoulder stress when treating and training fastpitch softball players.

Factors Contributing to Pelvis Instability in Female Adolescent Athletes During Unilateral Repeated Partial Squat Activity

Objectives: Unilateral partial squat tasks are often used to assess athletes’ lower extremity (LE) neuromuscular control. Single squat biomechanics such as lateral drop of the non-stance limb’s pelvis have been linked to knee injury risk. Yet, there are limited studies on the factors contributing to pelvic instability during the unilateral partial squat such as anatomical alignment of the knee and hip strength. The purpose of this study was 1) to assess the influence of leg dominance on pelvic drop among female athletes during the repeated unilateral partial squat activity and 2) to investigate the contributions that lower limb kinematics and hip strength have on pelvis drop. Methods: 42 female athletes (27= softball pitchers, 15=gymnasts, avg age=16.48 ± 2.54 years) underwent lower limb assessment. The quadriceps angle (Q angle) and the average of 3 trials for hip abduction and extension strength (handheld dynamometer measurements) were used for analyses. 3D biomechanical analysis of the repeated unilateral partial squat activity followed using a 20 motion capture camera system which created a 15 segment model of each subject. The subject stood on one leg at the lateral edge of a 17.78 cm box with hands placed on the hips and squatted so that the free hanging contralateral limb came as close to the ground without contact for 5 continuous repetitions. One trial for each limb was performed. Peak pelvic drop and ankle, knee and hip angles and torques (normalized by weight) at this time point were calculated using Visual 3D (C-Motion) biomechanical software. Paired T-test, Spearman correlations and multiple regression model statistical analyses were performed. Results: Peak pelvic drop during the unilateral partial squat did not differ significantly on the basis of limb dominance (p=0.831, Dom: -3.40 ± 5.10° , ND: -3.46 ± 4.44°). Peak pelvic drop displayed a Spearman correlation with the functional measure of hip abduction/adduction (ABD/ADD) angle (rs= 0.627, p< 0.001) (Figure 1). No association was noted between peak pelvic drop and anatomical measures of Q angle or isometric hip extension strength. A multiple regression was performed to predict pelvis drop angle from the following 6 variables: isometric hip ABD strength, hip ABD/ADD angle, hip internal/external rotation angle, ankle supination/pronation (S/P) angle, height and weight. These variables statistically predicted pelvis drop, F(6,73) = 17.848, p < .0005, R2 = 0.595. The strongest combined predictor variables for pelvic drop in the female athletes were hip abduction/ adduction angle and strength followed by subject’s weight and ankle S/P angle (Table 1). Conclusion: Peak pelvic drop during the repeated unilateral partial squat activity did not correlate significantly with Q angle and hip extension strength. Instead, peak pelvic drop appears more related to a combination of biomechanical limb positioning, hip ABD strength and subject demographics. The regression model run on the repeated unilateral partial squat demonstrates predictive power of this dynamic assessment tool based on kinematic measures across multiple joints. Results could guide clinician screening for excessive pelvic drop in female athletes and based on the predictive model make recommendations for corrective conditioning to help prevent knee injury and guide return to sport following LE surgery. Table 1: Multivariate linear regression model for pelvic drop, Isometric hip strength and lower extremity kinematics during repeated partial squat activity among female athletes. Variable P Isometric hip abduction strength 0.034* Hip Abduction/Adduction Angle <0.001* Hip Internal/External Rotation Angle 0.936 Ankle Internal/External Rotation Angle 0.072 Height 0.398 Weight 0.011* * Level of significance established at p<0.05