A. Joseph Threlkeld

Temporospatial and kinematic gait alterations during treadmill walking with body weight suspension

Our purpose was to analyze the effects of selected levels of body weight support (BWS) on lower extremity kinematics of normal subjects at a predetermined treadmill speed. Seventeen non-disabled volunteers walked on a treadmill at 1.25 ms(-1). Temporospatial and kinematic data were collected while various support levels were applied (Minimal, 10, 30, 50 and 70% BWS). Compared to 10% BWS, significant temporospatial and kinematic changes were induced by 50 and 70% BWS. Fewer differences were induced by 30% BWS compared to 10% BWS. We concluded that gait patterns of unimpaired subjects are significantly changed by 50 and 70% BWS.

Surface muscle pressure as a measure of active and passive behavior of muscles during gait

While surface electromyography (SEMG) can accurately register electrical activity of muscles during gait, there are no methods to estimate muscular force non-invasively. To better understand the mechanical behavior of muscle, we evaluated surface muscle pressure (SMP) in conjunction with SEMG. Changes in anterior thigh radial pressure during isometric contractions and gait were registered by pressure sensors on the limb. During isometric knee extensions by a single subject, SMP waveforms correlated well with SEMG (r=0.97), and SEMG onsets preceded those of SMP by 35-40 ms. SMP and SEMG signals were simultaneously recorded from the quadriceps of 10 healthy subjects during gait at speeds of 0.4, 0.8, 1.1, 1.4 and 2.2m/s. Muscle activity onset and cessation times were objectively determined for both modalities, and results showed high intra-class correlations. SMP waveforms were highly consistent from stride to stride, while SEMG waveforms varied widely. SEMG waveforms were typically brief, while SMP waveforms tended to be biphasic and outlasted the SEMG by approximately 40% of gait cycle at all speeds. These results are consistent with mechanical models of muscle, and demonstrate the use of SMP to estimate the timing of knee extensor muscle stiffness during gait.

Analysis of interactive effect of stretch reflex and shortening reaction on rigidity in Parkinson’s disease ☆

OBJECTIVE To examine the correlation between rigidity and interaction of stretch reflex and shortening reaction during passive movements of the wrist and to compare this correlation with that between rigidity and stretch reflex alone. METHODS Twelve subjects with Parkinsons disease participated in the study in Off-medication and On-medication states. A servomotor imposed wrist flexion and extension within +/-30 degrees at velocities 50 and 280 degrees/s, while joint torque and EMG of the wrist flexors and extensors were recorded. Rigidity was quantified by integrating torque with joint angle, i.e., objective rigidity (OR) score, for extension and flexion, respectively. The interaction between EMG responses was estimated by calculating a ratio of normalized EMG in stretched to shortened muscles for both movements. RESULTS The OR scores were more strongly correlated with the EMG ratios than with EMG of the stretched muscles alone. The strongest and significant correlation was found between the OR score and EMG ratio during the extension at high velocity in the Off-medication (r=0.792, p=0.002). CONCLUSIONS Both stretch reflex and shortening reaction are important determinants of rigidity. SIGNIFICANCE Study findings provide new insight into mechanistic descriptions of rigidity and have implications for development and evaluation of interventions.

Fibular taping does not influence ankle dorsiflexion range of motion or balance measures in individuals with chronic ankle instability

OBJECTIVES To determine the effects of fibular taping on ankle dorsiflexion range of motion (ROM) and dynamic balance in individuals with chronic ankle instability (CAI). DESIGN Single-blind, randomized crossover. METHODS Twenty-three individuals (age=23.4 ± 2.5 years, height=171.6 ± 12.4 cm, mass=71.5±13.1 kg) with CAI were allocated to either a fibular taping intervention or sham taping intervention (tape applied without tension) over the course of two visits. Weight-bearing ankle dorsiflexion ROM and components of the Star Excursion Balance Test (SEBT) were measured before and after intervention. RESULTS There was not a significant change in ankle dorsiflexion ROM when comparing the taping interventions (F1,43=1.03, P=.32), but both interventions resulted in a small increase (F1,43=8.07, P=.007) in dorsiflexion ROM (pre=36.7° ± 6.9°, post=37.7° ± 6.2°). This increase in ROM did not exceed the established minimal detectable change for dorsiflexion ROM. Fibular taping with tension produced an increase (F1,41=5.84, P=.02) (pre=69.0 ± 9.1%, post=70.6±8.6%) in posterolateral reach distance when compared to taping without tension (pre=72.7 ± 11.0%, post=71.4 ± 9.6%), but this increase did not exceed the established minimal detectable change. There was not a significant change in dynamic balance between groups for the anterior (F1,41=2.33, P=.14) and posteromedial (F1,41=.41, P=.53) reach directions. CONCLUSIONS Although small changes in ankle dorsiflexion ROM and posterolateral reach distances were observed, these changes did not exceed established minimal detectable change values for these measures. These results suggest that the benefits of fibular taping are not related to an increase in ankle dorsiflexion ROM or dynamic balance.

Optimal Stimulation Parameters to Detect Deficits in Quadriceps Voluntary Activation

Abstract Grindstaff, TL and Threlkeld, AJ. Optimal stimulation parameters to detect deficits in quadriceps voluntary activation. J Strength Cond Res 28(2): 381–389, 2014—The purpose of this study was to determine optimal stimulation parameters and calculation methods to estimate quadriceps voluntary activation while minimizing participant discomfort. Twelve healthy adults (8 men and 4 women; mean ± SD, age = 36.8 ± 15.6 years, weight = 76.1 ± 12.9 kg, height = 170.2 ± 8.6 cm). Repeated maximal volitional isometric contractions (MVIC) were performed while imposing 4 stimulation combinations (10 or 2 pulses; 400 or 200 V; and variable or standardized current) with the quadriceps in a relaxed state (resting twitch [RT]) and during an MVIC. Quadriceps activation was quantified by calculating the central activation ratio and the percent activation. Discomfort was quantified using the visual analog scale. When comparing calculation methods between the same stimulation parameters, the central activation ratio calculation method produced quadriceps activation values that were significantly greater (p < 0.009) than those derived using the percent activation calculation method. The doublet pulse stimulus produced less discomfort during the RT (p < 0.04) and MVIC (p < 0.001) when compared with all other combinations using a train of stimuli (10 pulses). Correlations for all estimates of quadriceps activation were strong (r = 0.85–0.99, p < 0.001). A doublet pulse stimulus produced discomfort levels that were over 50% lower than a 10-pulse train of stimuli and correlated well (r > 0.88) with activation levels obtained with a 10-pulse train of stimuli. Therefore, the use of a doublet pulse stimulus provides quadriceps activation information equivalent to other methods while minimizing participant discomfort.

Entry-level physical therapist education in the United States of America

Abstract Schools for physical therapist education in the US began in the latter part of the 19th century. The American Physical Therapy Association was formed in 1921 and has assumed a leadership role in fostering the quality and consistency of physical therapist education and practice. Growth in the number and complexity of physical therapist educational programmes during the first half of the 20th century was driven, in large part, by the need for rehabilitation of injured military personnel and by the polio epidemics. Physical therapist education in the US is now firmly embedded in an academic model of higher education and is rapidly converting to the doctoral entry-level degree, similar to other US educational tracks that produce autonomous healthcare practitioners. The future trends in US physical therapist education are seen in the establishment of organised residencies and fellowships. This, in turn, fosters autonomous practice and clinical specialisation.

Body weight supported treadmill training at very low treatment frequency for a young adult with incomplete cervical spinal cord injury

INTRODUCTION Body weight supported treadmill training (BWSTT) using high treatment frequency has been shown to improve gait after spinal cord injury (SCI). This case report describes the use of BWSTT at a very low treatment frequency. SUBJECT The subject was a 19 y.o. female with an incomplete C6 SCI, one year post-injury, with multiple gait deficits. INTERVENTION BWSTT was combined with conventional rehabilitation. Mean treatment frequency was 1.16 days/wk over 28.5 wks. A BWSTT progression algorithm based on observational gait analysis guided progressive changes in support levels, treadmill speed, and session length. OUTCOMES During the first 3 sessions, the subject tolerated an average of 15.7 minutes of BWSTT with 26% BWS at 0.8 m/s, improving to an average of 28 minutes of BWSTT with 10% BWS at 1.6 m/s in the last 3 sessions. Following 28.5 wks of very low frequency BWSTT, the subject displayed improved kinematics, walking speed, endurance, and distance during overground gait. CONCLUSION Very low frequency BWSTT combined with conventional treatment improved quality and endurance of walking for a person with incomplete cervical SCI. Further work is needed to evaluate the long-term outcome of very low frequency BWSTT and the interaction of BWSTT with other interventions.

Describing the clinical reasoning process: Application of a model of enablement to a pediatric case

Background and purpose: Clinical reasoning is a core tenet of physical therapy practice leading to optimal patient care. The purpose of this case was to describe the outcomes, subjective experience, and reflective clinical reasoning process for a child with cerebral palsy using the International Classification of Functioning, Disability, and Health (ICF) model. Case description: Application of the ICF framework to a 9-year-old boy with spastic triplegic cerebral palsy was utilized to capture the interwoven factors present in this case. Interventions in the pool occurred twice weekly for 1 h over a 10-week period. Outcomes: Immediately post and 4 months post-intervention, the child made functional and meaningful gains. The family unit also developed an enjoyment of exercising together. Each individual family member described psychological, emotional, or physical health improvements. Discussion: Reflection using the ICF model as a framework to discuss clinical reasoning can highlight important factors contributing to effective patient management.

Longitudinal gait analysis of a person with a transfemoral amputation using three different prosthetic knee/foot pairs

Using gait analysis, we documented kinetic and temporospatial changes over a 7–year period in a single healthy individual with a transfemoral amputation walking with three different knees and matched foot components. The knee/foot pairs in chronological order were Four Bar Endolite knee/Endolite Dynamic Response foot; Ossur Total Knee 2000/Pathfinder I foot; and C-Leg knee/IC40 C-walk foot. The design of the suspension and socket were unchanged across the three prostheses. We found an increase in the braking component of A-P ground reaction force on the intact limb while using the C-Leg compared to the other two prosthetic fabrications. There was progressive change across the three component combinations, which included increased step length, increased walking velocity, and decreased double limb support time. The subject ranked the C-Leg system as the most stable. The final gait pattern with the C-Leg was faster, less cautious, and more stable than with the other prosthetic components.

Quantifying thigh muscle co-activation during isometric knee extension contractions: Within- and between-session reliability

Muscle co-activation around the knee is important during ambulation and balance. The wide range of methodological approaches for the quantification of co-activation index (CI) makes comparisons across studies and populations difficult. The present study determined within- and between-session reliability of different methodological approaches for the quantification of the CI of the knee extensor and flexor muscles during maximum voluntary isometric contractions (MVICs). Eight healthy volunteers participated in two repeated testing sessions. A series of knee extension MVICs of the dominant leg with concomitant torque and electromyographic (EMG) recordings were captured. CI was calculated utilizing different analytical approaches. Intraclass correlation coefficient (ICC) showed that within-session measures displayed higher reliability (ICC>0.861) and lower variability (Coefficient of variation; CV<21.8%) than between-session measures (ICC<0.645; CV>24.2%). A selection of a 500ms or larger window of RMS EMG activity around the PT delivered more reliable and less variable results than other approaches. Our findings suggest that the CI can provide a reliable measure for comparisons among conditions and is best utilized for within-session experimental designs.