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 deg s-1 to 90 deg 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 use of higher eccentric movement velocities, and the addition of active recovery periods, are featured in the proposed theoretical periodization model for isokinetic eccentric strengthening

Interrater reliability of quantitative ultrasound using force feedback among examiners with varied levels of experience

Background. Quantitative ultrasound measures are influenced by multiple external factors including examiner scanning force. Force feedback may foster the acquisition of reliable morphometry measures under a variety of scanning conditions. The purpose of this study was to determine the reliability of force-feedback image acquisition and morphometry over a range of examiner-generated forces using a muscle tissuemimicking ultrasound phantom. Methods. Sixty material thickness measures were acquired from a muscle tissue mimicking phantom using B-mode ultrasound scanning by six examiners with varied experience levels (i.e., experienced, intermediate, and novice). Estimates of interrater reliability and measurement error with force feedback scanning were determined for the examiners. In addition, criterion-based reliability was determined using material deformation values across a range of examiner scanning forces (1–10 Newtons) via automated and manually acquired image capture methods using force feedback. Results. All examiners demonstrated acceptable interrater reliability (intraclass correlation coefficient, ICC = .98, p \u3c .001) for material thickness measures obtained using force feedback. Individual examiners exhibited acceptable reliability with the criterion-based reference measures (ICC \u3e .90, p \u3c .001), independent of their level of experience. The measurement error among all examiners was 1.5%–2.9% across all applied stress conditions. Conclusion. Manual image capture with force feedback may aid the reliability of morphometry measures across a range of examiner scanning forces, and allow for consistent performance among examiners with differing levels of experience

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 deg s-1 to 90 deg 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 use of higher eccentric movement velocities, and the addition of active recovery periods, are featured in the proposed theoretical periodization model for isokinetic eccentric strengthening

The association between musculoskeletal ultrasound measures and knee arthritis status in older Veterans

Background: Radiography is routinely used to assess knee osteoarthritis (OA), a degenerative condition involving articular cartilage and skeletal muscle. However, OA radiographic features do not consistently agree with patient-reported quality of life and other imaging modalities may offer better clinical utility. Diagnostic musculoskeletal ultrasound (MUS) can characterize muscle tissue structure and composition in knee OA. However, less is known about the association between MUS findings and patient symptomology. The purpose of this study is to determine whether quantitative MUS measures of skeletal muscle morphology and morphometry are associated with clinical markers of knee OA. Methods: Male Veterans with knee OA (n=36; age=62.2 ±5.7 yr; BMI=31.2 ±6.5) participated in the study. Self-reported symptoms and physical function were evaluated using the Knee injury and Osteoarthritis Outcome Score (KOOS). Knee OA asymmetry was determined by the Kellgren–Lawrence grade and self-reported pain. B-mode quantitative MUS with a 13-6 MHz linear array transducer were used to obtain tissue echogenicity and muscle thickness values. The primary scanning site was the rectus femoris of the participants more and less involved leg. Additional sites included the trapezius, deltoid, pectoralis major, and brachioradialis. Echogenicity was used as proxy measure of muscle tissue composition, and muscle thickness values were used as a proxy measure of muscle mass. Results: Lower echogenicity (D -3.04 grayscale levels, t=2.70, p=.01) and greater muscle thickness (D .17 cm, t=2.21, p=.03) of the rectus femoris were identified in the less involved limb. Additionally, the summed MUS muscle thickness values were associated with the Symptom and Sports/Recreation KOOS subscales (r=.37–.39, p=.02–.03). When considering individual muscle morphometry in the analyses, the muscle thickness of the deltoid was the only measure associated with all 5 KOOS subscales (r=.36–.45, p=.01–.04). Conclusions: MUS-based measures of muscle morphology and morphometry identified knee OA asymmetries in older adult Veterans. Key upper extremity muscle groups and proxy estimates of lean body mass should not be overlooked as factors that affect the KOOS score. Future work should explore the role of lean body mass in the management of knee OA, and determine if changes in rectus femoris echogenicity and muscle thickness are associated with disease status

The Association of Lower Extremity Strength with Step Ascent and Descent Performance in Men with Knee Osteoarthritis

Background: Knee osteoarthritis (OA) is a chronic disease characterized by articular cartilage damage, pain, and muscle weakness. Ambulating stairs is a leading source of pain in people with OA, and disease progression may be marked by asymmetrical gait abnormalities. The primary objective of this study was to determine the relationship between knee peak torque and Step-Up-and-Over (SUO) test performance in individuals with knee OA. The secondary objective was to assess asymmetries in the study participants based on knee peak torque and OA severity. Methods: Twenty-one male Veterans with knee OA (age = 59.8 yrs. ±4.5) from the Washington DC VA Medical Center enrolled in the study. The severity of knee OA was determined by a radiologist using the Kellgren–Lawrence (K-L) grading system during the assessment of participant x-rays. Functional performance was assessed via the SUO test, which involves ascending/descending an 8-inch box on a force plate. The SUO test outcomes included movement time and force-time parameters representing step-up force (concentric muscle control), step-down force (eccentric muscle control), and force-time curve smoothness (lower-limb motor coordination). Peak torque of the knee extensors and flexors were measured using isokinetic dynamometry (180º/s). Correlation analysis was used to determine the association between strength and SUO test outcomes. Paired t-tests were used to assess bilateral differences in peak torque and the K-L grades. Results: The mean within-participant difference in the K-L score was 0.7 ±0.6. Normalized knee peak torque was not significantly greater in the less involved leg (mean = .32 ±.14) compared to the more involved leg (mean = .27 ±.11; p \u3e .05), but was greater in the dominant leg (mean = .34 ±.13) versus the nondominant leg (mean = .25 ±.11; p = .001). Movement time during the SUO test was associated with knee extensor strength (r = -.41, p = 0.009), but not flexor strength (r = -.30, p = .056). Movement time was the only parameter measured during the SUO test that was associated with peak torque. Conclusions: Preliminary findings suggest that strength and OA severity asymmetries were minimal within the sample. Gross measures of knee extensor strength are associated with the movement time of the step ascent/descent task. However, the SUO force-time parameters may be associated with motor coordination rather than peak torque generation. Future work is needed to determine whether motor coordination improves independently of changes in knee strength over the course of OA treatment

Interrater reliability of quantitative ultrasound using force feedback among examiners with varied levels of experience

Background. Quantitative ultrasound measures are influenced by multiple external factors including examiner scanning force. Force feedback may foster the acquisition of reliable morphometry measures under a variety of scanning conditions. The purpose of this study was to determine the reliability of force-feedback image acquisition and morphometry over a range of examiner-generated forces using a muscle tissue-mimicking ultrasound phantom. Methods. Sixty material thickness measures were acquired from a muscle tissue mimicking phantom using B-mode ultrasound scanning by six examiners with varied experience levels (i.e., experienced, intermediate, and novice). Estimates of interrater reliability and measurement error with force feedback scanning were determined for the examiners. In addition, criterion-based reliability was determined using material deformation values across a range of examiner scanning forces (1–10 Newtons) via automated and manually acquired image capture methods using force feedback. Results. All examiners demonstrated acceptable interrater reliability (intraclass correlation coefficient, ICC = .98, p < .001) for material thickness measures obtained using force feedback. Individual examiners exhibited acceptable reliability with the criterion-based reference measures (ICC > .90, p < .001), independent of their level of experience. The measurement error among all examiners was 1.5%–2.9% across all applied stress conditions. Conclusion. Manual image capture with force feedback may aid the reliability of morphometry measures across a range of examiner scanning forces, and allow for consistent performance among examiners with differing levels of experience