A novel biomechanical indicator for impaired ankle dorsiflexion function during walking in individuals with chronic stroke

BACKGROUND

Ankle dorsiflexion function during swing phase contributes to foot clearance and plays an important role in walking ability post-stroke. Commonly used biomechanical measures such as foot clearance and ankle joint excursion have limited ability to accurately evaluate impaired dorsiflexor function.

RESEARCH QUESTION

Can ankle angular velocity and acceleration be used as reliable measurers of dorsiflexion function in post-stroke gait?

METHODS

Using linear regression and Pearson's correlation we retrospectively compared peak ankle angular velocity (AωP), peak ankle angular acceleration (AαP), peak dorsiflexion angle (DFAP) and peak foot clearance (FCLP) as direct measures for swing phase dorsiflexor function in 60 chronic stroke survivors. Intraclass correlation coefficient (ICC) analysis was used for test-retest reliability of AωP and AαP. RESULTS: Linear regression models revealed that AωP, AαP, DFAP, FCLP had a significant relationship (p < 0.05) with impaired dorsiflexion function. AαP and DFAP accounted for the most variance of dorsiflexion function. AωP, AαP, FCLP, correlated significantly with all clinical outcome measures of walking ability. DFAP had a positive correlation only with FMA-LE. Post-hoc William's t-tests, used to compare the magnitude of difference between two non-independent correlations, revealed that the correlation between all clinical measures and DFAP were significantly weaker than with AωP and AαP. Correlation between FMA-LE and FCLP was weaker than with AωP and AαP. Excellent test-retest reliability for both AωP (ICC = 0.968) and AαP (ICC = 0.947) was observed.

SIGNIFICANCE

These results suggest that DFAP may only be associated with dorsiflexion function during non-task specific isolated movements, but not during walking. FCLP is associated with dorsiflexion function and walking ability measures but not as strongly as AωP and AαP possibly because FCLP is influenced by contribution from hip and knee joint movements. Therefore, AωP and AαP are reliable measures and represent dorsiflexion function more accurately than DFAP, and FCLP.

The Functional Balance Ability Measure: A Measure of Balance Across the Spectrum of Functional Mobility in Persons Post-Stroke

Objective

To determine whether the measurement properties of an instrument that combines items from the Berg Balance Scale (BBS) and the Functional Gait Assessment (FGA) called the Functional Balance Ability Measure (FBAM) supports measuring balance across the functional mobility spectrum.

Design

Retrospective cohort.

Setting

Item-level data were from an archival research database.

Participants

Ambulatory individuals (N=93, BBS=50 [29-56], FGA=16 [0-30], Fugl-Meyer Assessment of Lower Extremities=27 [14-34], self-selected walking speed=0.4±0.2 m/s, mean age ± SD, 61.7±11.3y; 30.1% female) with chronic stroke (≥6 months).

Interventions

Not applicable.

Main Outcome Measures

Unidimensionality was evaluated with a principal components analysis (PCA) of residuals. FBAM rating-scale characteristics, item hierarchy, item and person fit, and person separation were investigated using the Andrich Rating Scale Model.

Results

PCA findings indicate the FBAM is sufficiently unidimensional. Rating scale structure was appropriate without modifying the original BBS and FGA scoring systems. Item hierarchy aligned with clinical and theoretical predictions (hardest item: FGA-gait with narrow base of support, easiest item: BBS-sitting unsupported). One item (BBS-standing on 1 foot) misfit, however, removal marginally affected person measures and model statistics. The FBAM demonstrated high person reliability (0.9) and 6 people (∼6%) misfit the expected response pattern. The FBAM separated participants into 4 statistically distinct strata, without a floor or ceiling effect.

Conclusions

The FBAM is a unidimensional measure for balance ability across a continuum of functional tasks. Rating-scale characteristics, item hierarchy, item and person fit, and person separation support the FBAM's measurement properties in persons with chronic stroke. Future work should investigate measurement with fewer items and whether the FBAM addresses barriers to adoption of standardized balance measures in clinical practice.

Conditional Minimal Detectable Change for the Cochlear Implant Quality of Life-35 Profile Associated With Improved Functional Abilities 12 Months After Cochlear Implantation

Importance

It is essential to measure an individual patient's baseline and follow-up abilities to demonstrate changes in clinical outcomes over time. Inherent in this strategy is interpreting whether the measured change is clinically significant and beyond measurement error. Conditional minimal detectable change (cMDC) values are widely used in many disciplines but have rarely been established for outcome measures in otolaryngology or hearing research, and never in cochlear implantation.

Objective

To determine cMDC values for the Cochlear Implant Quality of Life-35 (CIQOL-35) Profile instrument to enhance our understanding of the initial and ongoing changes in functional abilities from cochlear implants (CIs).

Design, Setting, and Participants

Item response theory analyses of responses from a multi-institutional cohort of 705 CI users at a tertiary CI center were used to derive standard error (SE) values for each possible CIQOL-35 domain score. Using an iterative approach, these SE values were used to calculate cMDC values for every possible pre-CI and post-CI domain score combination. We then compared pre-CI to 12-month post-CI CIQOL-35 domains scores in an independent cohort of 65 adult CI users to determine whether the measured change exceeded error to be clinically significant. The analysis took place on December 14, 2022.

Interventions

The CIQOL-35 Profile instrument and cochlear implantation.

Results

The cMDC values were smaller for the communication domain, and global measure and cMDC values for all domains were larger at the extremes of the measurement scale. Overall, 60 CI users (92.3%) demonstrated improvement beyond cMDC at 12 months post-CI for at least 1 CIQOL-35 domain, and no patients' scores declined beyond cMDC for any domain. The percentage of CI users demonstrating improvement beyond cMDC varied by domain, with communication (53 [81.5%]) showing the largest number of CI users improving, followed by global (42 [64.6%]) and entertainment (40 [60.9%]). In general, CI users who demonstrated improvement in CIQOL-35 domains had greater improvement in speech recognition scores than patients who did not, but the strength and significance of these associations greatly varied by domain and speech material.

Conclusions and Relevance

This multistep cohort study found that cMDC values for the CIQOL-35 Profile provided personalized thresholds for detecting real changes in patient self-reported functional abilities over time across multiple domains, which may inform clinical decision-making. Moreover, these longitudinal results reveal the domains with more or less improvement, which may aid in patient counseling.

Ultrasound measures of muscle morphology in people with multiple sclerosis are associated with muscle performance and functional mobility

BACKGROUND

Neurologically-based muscle weakness is a common symptom in people with multiple sclerosis MS (MS), who may also exhibit muscle morphology changes and intrinsic muscle dysfunction. Diagnostic ultrasound (sonography) is a non-invasive, inexpensive, and clinically feasible method to measure muscle morphology. The purpose of this study was to investigate possible asymmetries in lower limb muscle morphology and performance in people with MS, and to assess the relationships of muscle morphology measures with individual patient characteristics, muscle performance, and functional mobility.

METHODS

This cross-sectional study was conducted at the Washington, DC Veterans Affairs Medical Center. The study participants were 29 Veterans with MS (52% female, 79% African-American, 48.6 ± 11.2 years old, Mean Expanded Disability Status Scale: 3.6 ± 1.4) who completed seated knee extension isokinetic strength and power tests, functional assessments (Timed 25-Foot Walk - T25FW, 5-Times Sit-to-Stand - 5STS), and quantitative B-mode ultrasound image acquisition of the rectus femoris muscle to derive morphology measures (thickness and echogenicity). The limb with weaker knee extension strength was identified as the more-involved limb. Differences between the more and less-involved limb were quantified using a t-test for all muscle morphology and muscle performance measures. Relationships between muscle morphology and patient characteristics, muscle performance, and functional mobility were evaluated using bivariate and multivariate analyses.

RESULTS

The rectus femoris thickness from the more-involved limb was lower (p<0.001) than that of the less-involved limb, whereas echogenicity was not different between the two limbs (p=0.147). Rectus femoris thickness of the more-involved limb was directly related to age (r=-0.63, p<0.001), muscle strength (r=0.53, p=0.003) and power (r=0.53, p=0.003), and gait speed (r=0.42, p=0.024); whereas its echogenicity was positively associated only with muscle strength (r=-0.46, p=0.013) and power (r=-0.50, p=0.006). Together rectus femoris thickness and echogenicity of the more involved limb explained 44% and 48% of the variance in muscle strength and power, respectively (p<0.001).

CONCLUSION

This study supports the ability of sonography to measure muscle morphology in people with MS, identify asymmetries, and quantify associations with important clinical correlates. Compared with more invasive and costly alternatives, sonography is a clinically feasible, relatively low-cost tool that can be used to assess muscle morphology in people with MS. Further research is warranted to determine the potential clinical utility of sonographic measures of muscle morphology in evaluating changes due to disease progression or therapeutic interventions in this population.

A novel biomechanical indicator for impaired ankle dorsiflexion function during walking in individuals with chronic stroke

Ankle dorsiflexion function during swing phase of the gait cycle contributes to foot clearance and plays an important role in walking ability post-stroke. Commonly used biomechanical measures such as foot clearance and ankle joint excursion have limited ability to accurately evaluate dorsiflexor function in stroke gait. We retrospectively evaluated ankle angular velocity and ankle angular acceleration as direct measures for swing phase dorsiflexor function in post-stroke gait of 61 chronic stroke survivors. Our linear regression models revealed that peak ankle angular velocity (AAV P ), peak ankle angular acceleration (AAA P ), peak dorsiflexion angle (DFA P ) and peak foot clearance (FCL P ) during swing had a significant relationship (p < 0.05) with impaired dorsiflexion function. AAA P and DFA P accounted for the most variance of dorsiflexion function. Additionally, AAV P , AAA P , FCL P during swing, correlated significantly with all clinical outcome measures of walking ability. DFA P during swing had a positive correlation only with FMA-LE. Post-hoc William's t -tests, used to compare the magnitude of difference between two non-independent correlations, revealed that the correlation between all clinical measures and DFA P were significantly weaker than with AAV P and AAA P . We also found that correlation between FMA-LE and FCL P was weaker than with AAV P and AAA P . We found an excellent test-retest reliability for both AAV P (ICC = 0.968) and AAA P (ICC = 0.947). These results suggest that DFA P may only be associated with non-task specific isolated dorsiflexion movement, but not during walking. FCL P is associated with dorsiflexion function and walking ability measures but not as strongly as AAV P and AAA P possibly because FCL P is influenced by contribution from hip and knee joint movements during walking. Therefore, we believe that AAV P and AAA P both can be used as reliable measures of impaired dorsiflexion function in post-stroke gait.

Different aspects of hand grip performance associated with structural connectivity of distinct sensorimotor networks in chronic stroke

Knowledge regarding the neural origins of distinct upper extremity impairments may guide the choice of interventions to target neural structures responsible for specific impairments. This cross-sectional pilot study investigated whether different brain networks explain distinct aspects of hand grip performance in stroke survivors. In 22 chronic stroke survivors, hand grip performance was characterized as grip strength, reaction, relaxation times, and control of grip force magnitude and direction. In addition, their brain structural connectomes were constructed from diffusion tensor MRI. Prominent networks were identified based on a two-step factor analysis using the number of streamlines among brain regions relevant to sensorimotor function. We used regression models to estimate the predictive value of sensorimotor network connectivity for hand grip performance measures while controlling for stroke lesion volumes. Each hand grip performance measure correlated with the connectivity of distinct brain sensorimotor networks. These results suggest that different brain networks may be responsible for different aspects of hand grip performance, which leads to varying clinical presentations of upper extremity impairment following stroke. Understanding the brain network correlates for different hand grip performances may facilitate the development of personalized rehabilitation interventions to directly target the responsible brain network for specific impairments in individual patients, thus improving outcomes.

Variation of body weight supported treadmill training parameters during a single session can modulate muscle activity patterns in post-stroke gait

Evidence supporting the benefits of locomotor training (LT) to improve walking ability following stroke are inconclusive and could likely be improved with a better understanding of the effects of individual parameters i.e., body weight support (BWS), speed, and therapist assistance and their interactions with walking ability and specific impairments. We evaluated changes in muscle activity of thirty-seven individuals with chronic stroke (> 6 months), in response to a single session of LT at their self-selected or fastest-comfortable speed (FS) with three levels of BWS (0%, 15%, and 30%), and at FS with 30% BWS and seven different combinations of therapist assistance at the paretic foot, non-paretic foot, and trunk. Altered Muscle Activation Pattern (AMAP), a previously developed tool in our lab was used to evaluate the effects of LT parameter variation on eight lower-extremity muscle patterns in individuals with stroke. Repeated-measures mixed-model ANOVA was used to determine the effects of speed, BWS, and their interaction on AMAP scores. The Wilcoxon-signed rank test was used to determine the effects of therapist-assisted conditions on AMAP scores. Increased BWS mostly improved lower-extremity muscle activity patterns, but increased speed resulted in worse plantar flexor activity. Abnormal early plantar flexor activity during stance decreased with assistance at trunk and both feet, exaggerated plantar flexor activity during late swing decreased with assistance to the non-paretic foot or trunk, and diminished gluteus medius activity during stance increased with assistance to paretic foot and/or trunk. Therefore, different sets of training parameters have different immediate effects on activation patterns of each muscle and gait subphases.

Transcranial Direct Current Stimulation Electrode Montages May Differentially Impact Variables of Walking Performance in Individuals Poststroke: A Preliminary Study

PURPOSE

Transcranial direct current stimulation (tDCS) has mixed effects on walking performance in individuals poststroke. This is likely the result of variations in tDCS electrode montages and individualized responses. The purpose of this study was to quantify the effects of a single session of tDCS using various electrode montages on poststroke walking performance.

METHODS

Individuals with chronic stroke ( n = 16) participated in a double-blind, randomized cross-over study with sham stimulation and three tDCS electrode montages. Gait speed, paretic step ratio, and paretic propulsion were assessed prestimulation and poststimulation at self-selected and fastest comfortable speeds. Changes in muscle activation patterns with self-selected walking were quantified by the number of modules derived from nonnegative matrix factorization of EMG signals for hypothesis generation.

RESULTS

There was no significant effect of active stimulation montages compared with sham. Comparisons between each participant's best response to tDCS and sham show personalized tDCS may have a positive effect on fastest comfortable overground gait speed ( P = 0.084), paretic step ratio ( P = 0.095) and paretic propulsion ( P = 0.090), and self-selected paretic step ratio ( P = 0.012). Participants with two or three modules at baseline increased module number in response to the all experimental montages and sham, but responses were highly variable.

CONCLUSIONS

A single session of tDCS may affect clinical and biomechanical walking performance, but effects seem to be dependent on individual response variability to different electrode montages. Findings of this study are consistent with responses to various tDCS electrode montages being the result of underlying neuropathology, and the authors recommend examining how individual factors affect responses to tDCS.

The relationship between motor pathway damage and flexion-extension patterns of muscle co-excitation during walking

Background

Mass flexion-extension co-excitation patterns during walking are often seen as a consequence of stroke, but there is limited understanding of the specific contributions of different descending motor pathways toward their control. The corticospinal tract is a major descending motor pathway influencing the production of normal sequential muscle coactivation patterns for skilled movements. However, control of walking is also influenced by non-corticospinal pathways such as the corticoreticulospinal pathway that possibly contribute toward mass flexion-extension co-excitation patterns during walking. The current study sought to investigate the associations between damage to corticospinal (CST) and corticoreticular (CRP) motor pathways following stroke and the presence of mass flexion-extension patterns during walking as evaluated using module analysis.

Methods

Seventeen healthy controls and 44 stroke survivors were included in the study. We used non-negative matrix factorization for module analysis of paretic leg electromyographic activity. We typically have observed four modules during walking in healthy individuals. Stroke survivors often have less independently timed modules, for example two-modules presented as mass flexion-extension pattern. We used diffusion tensor imaging-based analysis where streamlines connecting regions of interest between the cortex and brainstem were computed to evaluate CST and CRP integrity. We also used a coarse classification tree analysis to evaluate the relative CST and CRP contribution toward module control.

Results

Interhemispheric CST asymmetry was associated with worse lower extremity Fugl-Meyer score (p = 0.023), propulsion symmetry (p = 0.016), and fewer modules (p = 0.028). Interhemispheric CRP asymmetry was associated with worse lower extremity Fugl-Meyer score (p = 0.009), Dynamic gait index (p = 0.035), Six-minute walk test (p = 0.020), Berg balance scale (p = 0.048), self-selected walking speed (p = 0.041), and propulsion symmetry (p = 0.001). The classification tree model reveled that substantial ipsilesional CRP or CST damage leads to a two-module pattern and poor walking ability with a trend toward increased compensatory contralesional CRP based control.

Conclusion

Both CST and CRP are involved with control of modules during walking and damage to both may lead to greater reliance on the contralesional CRP, which may contribute to a two-module pattern and be associated with worse walking performance.

Revisiting the Concept of Minimal Detectable Change for Patient-Reported Outcome Measures

Interpreting change is a requisite component of clinical decision making for physical therapists. Physical therapists often interpret change using minimal detectable change (MDC) values. Current MDC formulas are informed by classical test theory and calculated with group-level error data. This approach assumes that measurement error is the same across a measure's scale and confines the MDC value to the sample characteristics of the study. Alternatively, an item response theory (IRT) approach calculates separate estimates of measurement error for different locations on a measure's scale. This generates a conditional measurement error for someone with a low, middle, or high score. Error estimates at the measure-level can then be used to determine a conditional MDC (cMDC) value for individual patients based on their unique pre- and post-score combination. cMDC values can supply clinicians with a means for using individual score data to interpret change scores while providing a personalized approach that should lower the threshold for change compared with the MDC and enhance the precision of care decisions by preventing misclassification of patients. The purpose of this Perspective is to present how IRT can address the limitations of MDCs for informing clinical practice. This Perspective demonstrates how cMDC values can be generated from item-level psychometrics derived from an IRT model using the patient-reported Activities-specific Balance Scale (ABC) commonly used in stroke rehabilitation and also illustrates how the cMDC compares to the MDC when accounting for changes in measurement error across a scale. Theoretical patient examples highlight how reliance on the MDC value can result in misclassification of patient change and how cMDC values can help prevent this from occurring. This personalized approach for interpreting change can be used by physical therapists to enhance the precision of care decisions.

Measurement Precision and Efficiency of Computerized Adaptive Testing for the Activities-specific Balance Confidence Scale in People With Stroke

OBJECTIVE

Administrative burden often prevents clinical assessment of balance confidence in people with stroke. A computerized adaptive test (CAT) version of the Activities-specific Balance Confidence Scale (ABC CAT) can dramatically reduce this burden. The objective of this study was to test balance confidence measurement precision and efficiency in people with stroke with an ABC CAT.

METHODS

We conducted a retrospective, cross-sectional, simulation study with data from 406 adults approximately 2 months post-stroke in the Locomotor-Experience Applied Post-Stroke trial. Item parameters for CAT calibration were estimated with the Rasch model using a random sample of participants (n = 203). Computer simulation was used with response data from the remaining 203 participants to evaluate the ABC CAT algorithm under varying stopping criteria. We compared estimated levels of balance confidence from each simulation to actual levels predicted from the Rasch model (Pearson correlations and mean standard error [SE]).

RESULTS

Results from simulations with number of items as a stopping criterion strongly correlated with actual ABC scores (full item, r = 1, 12-item, r = 0.994; 8-item, r = 0.98; 4-item, r = 0.929). Mean SE increased with decreasing number of items administered (full item, SE = 0.31; 12 item, SE = 0.33; 8 item, SE = 0.38; 4 item, SE = 0.49). A precision-based stopping rule (mean SE = 0.5) also strongly correlated with actual ABC scores (r = 0.941) and optimized the relationship between number of items administrated with precision (mean number of items 4.37, range [4-9]).

CONCLUSION

An ABC CAT can determine accurate and precise measures of balance confidence in people with stroke with as few as 4 items. Individuals with lower balance confidence may require a greater number of items (up to 9) which could be attributed to the Locomotor-Experience Applied Post-Stroke trial excluding more functionally impaired persons.

IMPACT

Computerized adaptive testing can drastically reduce the ABC test's administration time while maintaining accuracy and precision. This should greatly enhance clinical utility, facilitating adoption of clinical practice guidelines in stroke rehabilitation.

LAY SUMMARY

If you have had a stroke, your physical therapist will likely test your balance confidence. A CAT version of the ABC scale can accurately identify balance with as few as 4 questions, which takes much less time.

Rasch Analysis of the Activities-Specific Balance Confidence Scale in Individuals Poststroke

Objective

To examine the psychometric properties of the Activities-specific Balance Confidence (ABC) scale using Rasch analysis for individuals poststroke.

Design

Retrospective cohort.

Setting

Data was extracted from the Locomotor Experience Applied Post-Stroke phase 3, multisite, randomized controlled clinical trial.

Participants

Community-dwelling, ambulatory, older adults (N = 406) (mean age ± SD, 61.97±12.76y; 45.07% female) approximately 2 months poststroke.

Intervention

None.

Main Outcome Measures

We examined unidimensionality, local dependence, rating-scale structure, item and person fit, person-item match, and separation index of the ABC scale.

Results

Confirmatory and exploratory factor analysis showed the ABC scale was adequately unidimensional and 3-item pairs had local dependence. A collapsed 5-category rating scale was superior to the 101-category scale. The hardest item was "walking outside on an icy sidewalk," the easiest item was "getting into or out of a car," and no items misfit. The ABC scale had high person reliability (0.93), despite 10.5% of individuals misfitting the expected response pattern. Mean ability level of the sample was slightly lower (-0.56 logits) than the mean item difficulty indicating that the ABC scale adequately matched our sample's balance confidence. The ABC scale did not have a floor or ceiling effect and separated individuals into 5 statistically distinct strata (separation index = 3.71).

Conclusions

The Rasch model supports the use of the ABC scale to measure balance confidence in individuals poststroke. The consistency of our results with previous Rasch analyses on the ABC scale demonstrates the instrument responds similarly across multiple populations; community-dwelling older-adults, outpatient orthopedic physical therapy, stroke, Parkinson disease, and lower-limb amputation. Recommendations include collapsing the rating scale and developing a computerized-adaptive test version of the scale to enhance clinical utility.

The Effect of Frailty on Discharge Location for Medicare Beneficiaries After Acute Stroke

OBJECTIVE

To examine the effect of frailty on poststroke discharge location with respect to stroke severity and create a risk-adjusted model for understanding the effects of frailty on discharge to an inpatient rehabilitation facility.

DESIGN

Retrospective cohort.

SETTING

A 2014 5% Medicare sample.

PARTICIPANTS

Patients hospitalized for a first-time acute ischemic stroke (N=7258).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

A prehospitalization 6-month baseline was used to calculate a frailty score. Logistic regression to predict odds of discharge to inpatient rehabilitation was used to calculate for 3 levels of baseline frailty, controlling for patient demographics, stroke severity, and comorbidities.

RESULTS

About 1603 patients were discharged to inpatient rehabilitation. Patients who were nonfrail (odds ratio [OR] 1.716; 95% confidence interval [95% CI], 1.463-2.013) or prefrail (OR 1.519; 95% CI, 1.296-1.779) were more likely to be discharged to inpatient rehabilitation. The final logistic regression model had a C-statistic of 0.63. Most of the patients discharged to inpatient rehabilitation were nonfrail (44.2%) and had moderate strokes (38.9%). Individuals who were frail and suffered a moderate (OR 0.78; 95% CI, 0.558-1.091) or severe stroke (OR 0.509; 95% CI, 0.358-0.721) were less likely to be discharged to an inpatient rehabilitation facility.

CONCLUSIONS

A lack of a claims-based measure for prestroke functional ability makes it difficult to understand discharge decision-making patterns for individuals' poststroke. Prestroke frailty was found to have a significant effect on predicating inpatient rehabilitation discharge after an acute stroke when controlling for stroke severity, comorbidities, and age. Further investigation is warranted to examine differences in rehabilitation utilization based on frailty and to quantify the effect of rehabilitation on frailty status in individuals poststroke.

Effect of frailty on resource use and cost for Medicare patients

Aim: The effects of frailty and multiple chronic conditions (MCCs) on cost of care are rarely disentangled in archival data studies. We identify the marginal contribution of frailty to medical care cost estimates using Medicare data. Materials & methods: Use of the Faurot frailty score to identify differences in acute medical events and cost of care for patients, controlling for MCCs and medication use. Results: Estimated marginal cost of frailty was US$10,690 after controlling for demographics, comorbid conditions, polypharmacy and use of potentially inappropriate medications. Conclusion: Frailty contributes greatly to cost of care, but while often correlated, is not synonymous with MCCs. Thus, it is important to control separately for frailty in studies that compare medical care use and cost.

Eccentric Exercise Program Design: A Periodization Model for Rehabilitation Applications

The applied use of eccentric muscle actions for physical rehabilitation may utilize the framework of periodization. This approach may facilitate the safe introduction of eccentric exercise and appropriate management of the workload progression. The purpose of this data-driven Hypothesis and Theory paper is to present a periodization model for isokinetic eccentric strengthening of older adults in an outpatient rehabilitation setting. Exemplar and group data are used to describe the initial eccentric exercise prescription, structured familiarization procedures, workload progression algorithm, and feasibility of the exercise regimen. Twenty-four men (61.8 ± 6.3 years of age) completed a 12-week isokinetic eccentric strengthening regimen involving the knee extensors. Feasibility and safety of the regimen was evaluated using serial visual analog scale (VAS, 0–10) values for self-reported pain, and examining changes in the magnitude of mean eccentric power as a function of movement velocity. Motor learning associated with the familiarization sessions was characterized through torque-time curve analysis. Total work was analyzed to identify relative training plateaus or diminished exercise capacity during the progressive phase of the macrocycle. Variability in the mean repetition interval decreased from 68 to 12% during the familiarization phase of the macrocycle. The mean VAS values were 2.9 ± 2.7 at the start of the regimen and 2.6 ± 2.9 following 12 weeks of eccentric strength training. During the progressive phase of the macrocycle, exercise workload increased from 70% of the estimated eccentric peak torque to 141% and total work increased by 185% during this training phase. The slope of the total work performed across the progressive phase of the macrocycle ranged from −5.5 to 29.6, with the lowest slope values occurring during microcycles 8 and 11. Also, mean power generation increased by 25% when eccentric isokinetic velocity increased from 60 to 90° s⁻¹ while maintaining the same workload target. The periodization model used in this study for eccentric exercise familiarization and workload progression was feasible and safe to implement within an outpatient rehabilitation setting. Cyclic implementation of higher eccentric movement velocities, and the addition of active recovery periods, are featured in the proposed theoretical periodization model for isokinetic eccentric strengthening.

Ultrasound estimates of muscle quality in older adults: reliability and comparison of Photoshop and ImageJ for the grayscale analysis of muscle echogenicity

Background. Quantitative diagnostic ultrasound imaging has been proposed as a method of estimating muscle quality using measures of echogenicity. The Rectangular Marquee Tool (RMT) and the Free Hand Tool (FHT) are two types of editing features used in Photoshop and ImageJ for determining a region of interest (ROI) within an ultrasound image. The primary objective of this study is to determine the intrarater and interrater reliability of Photoshop and ImageJ for the estimate of muscle tissue echogenicity in older adults via grayscale histogram analysis. The secondary objective is to compare the mean grayscale values obtained using both the RMT and FHT methods across both image analysis platforms. Methods. This cross-sectional observational study features 18 community-dwelling men (age = 61.5 ± 2.32 years). Longitudinal views of the rectus femoris were captured using B-mode ultrasound. The ROI for each scan was selected by 2 examiners using the RMT and FHT methods from each software program. Their reliability is assessed using intraclass correlation coefficients (ICCs) and the standard error of the measurement (SEM). Measurement agreement for these values is depicted using Bland-Altman plots. A paired t-test is used to determine mean differences in echogenicity expressed as grayscale values using the RMT and FHT methods to select the post-image acquisition ROI. The degree of association among ROI selection methods and image analysis platforms is analyzed using the coefficient of determination (R (2)). Results. The raters demonstrated excellent intrarater and interrater reliability using the RMT and FHT methods across both platforms (lower bound 95% CI ICC = .97-.99, p < .001). Mean differences between the echogenicity estimates obtained with the RMT and FHT methods was .87 grayscale levels (95% CI [.54-1.21], p < .0001) using data obtained with both programs. The SEM for Photoshop was .97 and 1.05 grayscale levels when using the RMT and FHT ROI selection methods, respectively. Comparatively, the SEM values were .72 and .81 grayscale levels, respectively, when using the RMT and FHT ROI selection methods in ImageJ. Uniform coefficients of determination (R (2) = .96-.99, p < .001) indicate strong positive associations among the grayscale histogram analysis measurement conditions independent of the ROI selection methods and imaging platform. Conclusion. Our method for evaluating muscle echogenicity demonstrated a high degree of intrarater and interrater reliability using both the RMT and FHT methods across 2 common image analysis platforms. The minimal measurement error exhibited by the examiners demonstrates that the ROI selection methods used with Photoshop and ImageJ are suitable for the post-acquisition image analysis of tissue echogenicity in older adults.