Isokinetic Measurements Research Articles

The examination of relationships between upper extremity joint lengths, reaction time and shoulder strength parameters in youth canoe athletes

The aim of this study was to investigate the relationships between upper extremity joint length, reaction time and shoulder strength in young canoe athletes. The study was carried out with the voluntary participation of 23 young canoe athletes. Within the scope of the research plan, height measurements, body weight measurements, length measurements of the upper extremities (arm and forearm length), arm span length measurements, reaction time measurements and isokinetic strength measurements of the athletes were carried out. The effect of joint length values on reaction time and shoulder strength parameters was examined by multiple linear regression analysis. The results show that joint length values have a significant effect on reaction time and shoulder strength values in canoe athletes (p

Feasibility and Reproducibility of Isokinetic Dynamometry in Children with Neuromuscular Diseases.

Background/Objectives: High-precision measurement tools are needed to measure relevant changes in strength and power in children with neuromuscular diseases. The aim of this study was to determine the feasibility (i), reproducibility (ii), and validity (iii) of isokinetic dynamometry in this population. Methods: Isometric and isokinetic knee and elbow flexion and extension were measured twice on the same day. Feasibility was based on completion rate and acceptability. Acceptability was measured with a 100 mm visual analog scale. We measured reproducibility as the intraclass correlation coefficient (ICC-agreement), standard error of measurement (SEM), and smallest detectable change (SDC). We investigated relationships between isometric strength and isokinetic power with Pearson's correlation coefficient. ROC curves were used to determine the cutoff of isometric strength to conduct isokinetic measurements. Results: Fifty children with NMDs participated with completion rates of 78-90% for isometric and 39-75% for isokinetic measurements. Acceptability was high (mean (SD) = 73 (19) mm). The ICCs for all measurements were over 0.9 (95% confidence interval (CI) = 0.932-0.998). The SEM% ranged from 5 to 14% and the SDC% from 14 to 28%. The correlations of strength and power were high (Pearson's correlation coefficient >0.9 (95% CI: 0.89-0.98)). The isometric strength needed to conduct isokinetic measurements ranged from 11.1 N in elbow flexors to 24.9 N in knee extensors. Conclusions: Isokinetic dynamometry is a feasible and reproducible method for measuring isometric strength in children with neuromuscular diseases with moderate weakness to normal strength, and isokinetic measurements are only feasible in knee extension for children with moderate weakness to normal strength. The convergent validity between isometric strength and power at low velocities is high.

The isometric and isokinetic knee extension and flexion muscle strength profile of elite soccer players

BackgroundThis study aimed to further complete normative data sets for the strength profile of the thigh in soccer players by performing isometric and isokinetic measurements in a large sample per player position.MethodsIn total, 364 soccer players were divided into subgroups according to their pitch position. All players performed isometric and isokinetic strength measurements during active competition period using an isokinetic dynamometer (System 3, Biodex®, ENRAF-NONIUS, New York, USA).ResultsIsokinetic strength of m. Quadriceps was significantly (p = 0.023) higher in strikers compared to central midfielders in both the dominant (+ 9%) and the non-dominant (+ 4%) leg. No further differences were found in isometric or isokinetic strength per playing positions.ConclusionsWe have shown that strength profiles do not differ between playing positions on the field. This is valuable information for elite soccer high performance coaches and medical staffs aiming to improve daily training efficiency and rehabilitation of their players.

Subacromial balloon spacer improves isokinetic performance in patients with massive irreparable rotator cuff tear.

The aim of this study was to analyse clinical, functional and shoulder kinematics results using subacromial balloon spacer in nonreparable massive rotator cuff tears. Subacromial balloon spacer was hypothesised to improve shoulder kinematics and increases clinical and functional outcomes scores in nonreparable massive rotator cuff tears. This is a prospective study in massive rotator cuff tears. From October 2021 to October 2022, a total of 127 shoulders suffering massive rotator cuff tears were initially evaluated. All patients were evaluated preoperatively, at 6 and 12 months. Patients' patient-reported outcome measures (PROM) subjective values using visual analogue scale (VAS) and the Spanish Western Ontario Rotator Cuff Index (WORC) version were analysed. We also evaluated objective outcomes: constant score, range of movement and kinematic shoulder analysis (isokinetic test to evaluate internal and external rotation forces). Statistical analysis was conducted using SPSS software; continuous variables were presented as means and standard deviations (SDs). Seventeen nonrepairable massive rotator cuff tears were finally included. Three patients required reverse shoulder arthroplasty before 6 months postoperative. After 1-year follow-up, objective and subjective (PROM) outcome scores and isokinetic measurements improved in 13 patients. Preoperative VAS improved from 6.5 ± 2.1 to 2 ± 1.9 points on average at 1-year follow-up and WORC index from 1603 ± 217.3 to 699 ± 361.6. Constant score from 42.1 ± 13.1 on average and at 1-year follow-up increased to 60.8 ± 14.7. Range of movement also improved in elevation 122.2 ± 39.3 to 166.9 ± 25.8, abduction 120.3 ± 38.6 to 134.6 ± 21.1, external rotation 30.3 ± 19.7 to 86.1 ± 13.8 and internal rotation L4-T12 on average at 1-year follow-up. Isokinetic evaluation showed functional improvement 1 year after implantation. Both internal and external rotation improved compared with their healthy shoulder. External rotation improved from 30.3° ± 19.7° preoperatively to 86.1° ± 13.8° (43.7% in the isokinetic study) and internal rotation from L4 preoperatively to L1 (49.8% in isokinetic study) on average. Among the different alternatives for irreparable rotator cuff injuries surgical treatment, subacromial balloon spacer is an effective alternative in selected patients, both in terms of clinical-functional improvement and short-term isokinetic results. Level II.

Unveiling the influence of hip isokinetic strength on lower extremity running kinematics in male national middle-distance runners: a correlational analysis

BackgroundThe relationship between hip strength deficiency in various planes and musculoskeletal injuries within the movement system has been well-established in numerous studies. The present study sought to explore the relationships between hip strength and specific aspects of lower extremity running kinematics.MethodologyTo achieve this objective, the three-dimensional running kinematics of 21 male elite middle-distance runners (mean age: 19.7 ± 1.2 years; mean experience 6.5 ± 1.0 years) were assessed using nine high-speed cameras on a treadmill at a speed of 16 km·h⁻¹. Concurrently, isokinetic hip strength was measured at a speed of 60 deg·s⁻¹ in both the dominant and non-dominant legs. The Pearson correlation coefficient and Paired Samples t-test were utilized.ResultsWhile no significant differences were found in several isokinetic strength measurements, notable differences in running kinematics were observed. Specifically, pelvic drop at midstance (MS) was significantly lower in the DL (5.79 ± 3.00°) compared to the NDL (8.71 ± 1.39°) with a large effect size (t=-4.04, p < 0.001, Cohen’s d = 1.25). Additionally, knee adduction at maximum showed a moderate effect size difference, with the DL at 2.99 ± 1.13° and the NDL at 3.81 ± 1.76° (t=-2.74, p = 0.03, Cohen’s d = 0.55). Results indicated a moderate to highly positive association between running knee adduction in the dominant leg and hip external rotation (r = 0.67, p < 0.05), concentric extension (r = 0.77, p < 0.05), and concentric abduction (r = 0.78, p < 0.05). Additionally, the running tibial external rotation angle in the dominant leg exhibited an inverse relationship with all strength measurements, with statistical significance observed only for concentric extension force (r=-0.68, p < 0.05). Furthermore, hip internal rotation force demonstrated a highly inverse correlation with foot pronation in the dominant leg (r=-0.70, p < 0.05) and anterior pelvic tilt in the non-dominant leg (r=-0.76, p < 0.05).ConclusionsThese findings underscore the interrelation between hip strength and running kinematics, particularly on the dominant side. In light of these observations, it is imperative to consider hip strength exercises as integral components for correcting running kinematics. Coaches should also be mindful that kinematic deviations contributing to running injuries may manifest unilaterally or specifically in the dominant leg.

The relationship between isokinetic knee flexion andsquat jump performance

BACKGROUND: Explosive power of the lower limbs is considered a powerful diagnostic method of the performance level of athletes. In the past, this issue has not yet been sufficiently explored. In the theoretical part, we tried using the available literature to approach the solved problem from the point of view of other authors. PURPOSE: The work aimed to verify and determine the existence of relationships between the isokinetic strength of the extensor joint and during the entire period in adolescent athletes of the Presov club. MATERIALS and METHODS: This study was carried out on adolescent athletes (n=21) who compete at the national level in the category of junior age. Average age 15.3 years, height 173 cm, weight 56 kg. Individual jumps SJ, CMJ, and CMJ FA were measured on Optojump. Isokinetic measurement of peak force and average force was performed in a bilateral version using a special adapter and IsoForce2 device at angular speeds of 50.s-1, 70.s-1, 90.s-1, 125.s-1, 155. s-1. We determined the relationships between individual variables using the Pearson correlation coefficient (r). RESULTS: Peak force values measured at an angular velocity of 155.s-1 on Izoforce2 correlated with SJ and CMJ jumps at the p &lt; .05000 significance level. With average force values measured on isokinetic equipment, a significant relationship was demonstrated at an angular velocity of 155.s-1 in SJ, CMJ, and CMJ FA jumps at the level of significance p &lt; .05000. The measured average values at an angular velocity of 125.s-1 were correlated at the level of significance p &lt; .05000 only in SJ and CMJ FA jumps. CONCLUSIONS: The results of the work indicate that there is a relationship between vertical jumps and the values measured on isokinetic devices, which strengthens the claim about the importance of these muscle parts during the vertical jump as one of the limiting factors of performance in athletics. Due to the small number of people examined and the high variability of the results of similar studies, we recommend confirming the results that further measurements are also carried out at higher angular velocities of 180.s-1 to 230.s-1, in different periods of the athletes' training.

The relationship between hamstring strength tests and sprint performance in female Gaelic footballers: A correlation and linear regression analysis.

To investigate the relationships between handheld dynamometer (HHD), isokinetic and Nordic hamstrings exercise (NHE) measurements of knee flexor strength and their association with sprinting performance. Cross-sectional. The relationships between HHD (prone isometric, prone break and supine break knee flexor strength tests), isokinetic and NHE peak knee flexor strength measures were examined using Pearson product correlations on 38 female footballers. A linear regression analysis was also performed for each pair of dependent variables (10 and 30 metre sprint times) and independent predictor variables (average relative peak torque for HHD, isokinetic and NHE testing). There were good correlations between HHD tests (r = 0.81-0.90, p < 0.001, R2 = 0.65-0.82), moderate correlations between HHD and isokinetic peak torque, (r = 0.61-0.67, p < 0.001, R2 = 0.37-0.44) and poor association between the HHD peak torques and isokinetic work (r = 0.44-0.46, p = 0.005-0.007, R2 = 0.20-0.21) and average power (r = 0.39-0.45, n = 36, p = 0.006-0.019, R2 = 0.15-0.22). There was a poor association between NHE peak torque and isokinetic total work (r = 0.34, p = 0.04, R2 = 0.12). No associations between knee flexor strength and sprint times were observed (p = 0.12-0.79, r2 = 0.002-0.086). Moderate to good correlations within HHD testing and poor to moderate correlations between HHD and isokinetic testing were observed. HHD knee flexor torque assessment may be useful to regularly chart the progress of hamstring rehabilitation for female footballers. Knee flexor strength assessments were not associated with sprint times in female footballers. Other aspects of knee flexor strength and sprint performance should be investigated to assist clinicians in making return to running and sprinting decisions in this population.

Assessing quadriceps strength in patellofemoral pain patients: A study on the reliability and validity of a low-cost strain-gauge for clinical practice.

Patellofemoral pain (PFP) is a common knee complaint affecting diverse populations both acutely and chronically. Quadriceps muscle weakness is one possible aetiology, but current devices for measuring muscle strength (isokinetic dynamometer [ID] and hand-held dynamometers [HHD]) are frequently too expensive (e.g., ID) or lack reliability (e.g., HHD) for practitioners, especially in under-resourced settings. There is a need to evaluate a low-cost device to manage rehabilitation of people with PFP. Isometric quadriceps strength of participants aged 18-35 years (total [n = 33], control group [n = 17] and PFP group [n = 16]) were evaluated on an isokinetic dynamometer and a commercially available strain gauge at baseline and after an 8-week non-standardised intervention. The strain gauge showed high absolute and relative reliability (intraclass correlation coefficient = 0.89-0.99; typical error of measurement = 3.9-10.4%). Clinically meaningful difference scores (12.2-45 Nm) were greater than the typical error of measurement, implying sufficient sensitivity of the strain gauge to measure true changes in isometric quadricep strength. Strong to very strong correlations were evident between the strain gauge and isokinetic dynamometer torque measurements (r = 0.88-0.90, SEE = 0.05-0.07 Nm), but slope values (β = 0.65-0.77) indicated that torque from the strain gauge was lower than that obtained from the isokinetic dynamometer. An average systematic bias of 16.3-28.8 Nm was evident in favour of the isokinetic dynamometer, with no statistically significant between-group differences apparent between baseline and follow-up testing. The present commercially available strain gauge is reliable and sensitive enough to detect clinically meaningful differences in quadriceps strength of both healthy individuals and those with PFP. However, the strain gauge lacks validity and therefore cannot replace isokinetic dynamometry. Given the low cost and excellent reliability, the strain gauge can be a valuable tool to assess quadriceps muscle deficits and track rehabilitation progress in people with PFP.

Does It Matter? Isometric or Isokinetic Assessment of Quadriceps Strength Symmetry 9 Months After ACLR in Collegiate Athletes.

Greater quadriceps strength symmetry is associated with better outcomes after anterior cruciate ligament reconstruction (ACLR). Isometric and isokinetic assessments of quadriceps strength inform therapeutic exercise prescription and return-to-sport decisions. It is unclear whether isometric and isokinetic measures provide similar information post-ACLR. Quadriceps strength symmetry is similar between isometric and isokinetic assessments. Isokinetic and isometric strength symmetries have similar associations to functional knee kinetics and self-reported knee function. Cross-sectional study. Level 3. NCAA Division I athletes (N = 35), 8.9 ± 2.5 months post-ACLR completed isometric and isokinetic quadriceps strength assessments, countermovement jumps (CMJs), and treadmill running. Self-reported knee function was assessed using the International Knee Documentation Committee Subjective Knee Form (IKDC). Agreement between isometric and isokinetic strength symmetry was assessed using Bland-Altman analysis, with associations to functional knee kinetics and IKDC assessed using Pearson correlations and linear regressions. Mean difference in quadriceps strength symmetry between isokinetic and isometric assessments was 1.0% (95% limits of agreement of -25.1% to 23.0%). Functional knee kinetics during running and CMJ were moderately to strongly associated with isometric strength symmetry (r = 0.64-0.80, P < 0.01) and moderately associated with isokinetic strength symmetry (r = 0.41-0.58, P < 0.01). IKDC scores were weakly to moderately associated with isometric (r = 0.39, P = 0.02) and isokinetic (r = 0.49, P < 0.01) strength symmetry. Isokinetic and isometric assessments of quadriceps strength symmetry in collegiate athletes 9 months post-ACLR demonstrated strong agreement. Quadriceps strength symmetry is associated with functional knee kinetic symmetry post-ACLR. Considerable individual variation suggests mode of contraction should be consistent throughout postoperative assessment. Isometric strength symmetry may be a better indicator of functional knee kinetic symmetry, while isokinetic strength symmetry may be associated more closely with patient-reported outcomes.

Biceps brachii elastography in well-trained men post eccentric exercise-induced muscle damage.

Recent advancements in elastography techniques, specifically supersonic shearwave elastography (SWE), have enabled non-invasive assessment of muscle stiffness. However, there is limited research on the immediate and short-term effects of eccentric exercise-induced muscle damage (EIMD) in well-trained individuals. This study aimed to follow up on the effects of eccentric training on the biceps brachialis stiffness by supersonic shearwave imaging (SSI) as well as the soreness and elbow flexion maximal voluntary isometric contraction (MVIC), immediately post-intervention, at 10min, 48h, and 96h in well-trained men. Thirteen well-trained males participated in the study. Baseline measurements of elastography images, MVIC of the elbow flexors, and muscle soreness were obtained. The participants performed an eccentric exercise protocol (4 sets X 10 repetitions) on the dynamometer isokinetic and elastography measurements were repeated immediately post-exercise, at 10min, 48h, and 96h. Significant reductions in stiffness (measured by shear modulus (µ)) were observed immediately and at 10min post-exercise. MVIC exhibited significant reductions immediately after, 10min, and 48h compared to baseline measurements. Muscle soreness peaked at 48h, persisting until 96h. The BB stiffness and MVIC reduction immediately post-eccentric exercise in well-trained men, suggest the potential involvement of mechanical stress and sarcomere rupture. Trained individuals may exhibit a distinct response to EIMD compared to untrained individuals, highlighting the applicability of elastography in monitoring acute biomechanical changes following high-intensity exercise.

Isokinetic strength and experience: Analyzing key attributes in professional soccer players

Soccer is one of the sports where performance is shaped by the coming together of numerous variables. The importance of strength, a physical variable that determines performance, is thought to be as crucial as the experience levels of athletes, which are also considered important for performance. The present study aimed to compare the isokinetic strength characteristics and soccer experience of professional league (PRL) and amateur league (AML) soccer players. After recording variables such as total playing seasons and weekly training sessions, isokinetic strength measurements were conducted at angular velocities of 60°/sec and 180°/sec. The outcomes revealed that PRL players engaged in significantly more weekly training sessions and had accumulated a higher total number of playing seasons than their AML counterparts (p

Is the isokinetic strength of nonparetic lower limb related to fatigue in stroke survivors? A cross-sectional study.

The study aimed to investigate the correlation between nonparetic knee muscle strength and fatigue in a cohort of stroke survivors. Thirty-two stroke survivors (17 females, 15 males; median age 62 (interquartile range [IQR] 51-69), (min: 45, max: 81) years were recruited in this cross-sectional study between January 2012 and September 2012. Sociodemographic, clinical, and stroke-related parameters were recorded. All participants underwent an isokinetic measurement of the nonparetic knee flexion and extension. Functional independence measure, functional ambulation category, and Mini-Mental State Examination scores were used to evaluate the functional status, ambulation, and mental status of the patients. Anxiety, depression, and fatigue severity were measured using the Hospital Anxiety and Depression Scale and fatigue severity scale (FSS), respectively. The median duration of stroke was 3.1 (IQR: 2.5-6.5) months. Stroke survivors with reduced muscle strength were older and had lower motor and total functional independence measure scores than those with normal strength (p=0.026, p=0.034, and p=0.034, respectively). There were more patients with lower functional ambulation category scores in the group with reduced muscle strength (p=0.023). Peak torque values of knee flexors at 60°/sec and 180°/sec correlated negatively with FSS (r= -0.360, p=0.043 and r= -0.452, p=0.009, respectively). There was also a negative correlation between the work of knee extensor and flexors at 180°/sec and FSS (r= -0.398, p=0.024 and r= -0.451, p=0.010, respectively). Anxiety and depression scores were not significantly correlated with fatigue. The lower strength of nonparetic knee extensor muscles was related to greater disability and worse ambulatory scores. The lower strength of knee flexor muscles and the work of both knee muscles in the nonparetic limb were related to higher fatigue levels in stroke survivors. Therefore, fatigue management and strengthening of both knee flexor and extensor muscles in the nonparetic limb is emphasized during stroke rehabilitation.

New hand dynamometer activforce isometric muscle activation on single joint muscle force of volleyball players

Isometric muscle activation of single joint to volleyball players is critic on sport performance to produce potential muscle force, however isometric measurement limited in isokinetic muscle activity measurement of volleyball players. Indeed, hand dynamometers commonly use in various body isometric force. Professional volleyball players age 16.23 ± 0.59 yr, body mass 60.22 ± 4.64 kg, hight 1.69 ± 0.04 m participated to peak and average isometric force measurement over 8 week pre and post test. Accordingly, single joint muscle force production measurement of volleyball players tested on isometric muscle activation using a new hand dynamometer activforce 2. Isometric muscle activation tests consisted of 24 body region from upper and lower compartment. For this isometric muscle action test detected on peak force outcomes (SEM: 37.90; CV: 1.79) and average force outcomes (SEM: 33.62; CV: 1.84). The high isometric muscle action joint loading performing mechanical test application recommended on athletic population to using isometric potential high contraction model by strength training performance separately in-season and off-season measurement modeling. Conclusion, peak and average force production progressive isometric modeling of volleyball athletes worked to current sport–health condition. As out, conclusion must be advanced isometric force measurement proper work in sport-specific tasks. The proper isometric force must be repeat sport performance outcome in different sport modalities.

Testing the Posterior Chain: Diagnostic Accuracy of the Bunkie Test versus the Isokinetic Hamstrings/Quadriceps Measurement in Patients with Self-Reported Knee Pain and Healthy Controls.

(1) Background: The isokinetic measurement (IM) of the leg muscles is well established but costly, whereas the Bunkie Test (BT) is a rarely investigated but easy-to-conduct functional test to evaluate the total posterior chain. Although the tests differ in aim and test structures, both have their justification in the assessment process. Therefore, this study evaluated the diagnostic accuracy of the BT and the IM. (2) Methods: 21 participants (9 female, 12 male; age, 26.2 ± 5.26 years; weight 73.8 ± 14.6 kg; height 176.0 ± 9.91 cm) and 21 patients (9 female, 12 male; age, 26.5 ± 5.56 years; weight, 72.6 ± 16.9 kg; height 177.0 ± 10.1 cm) with self-reported pain in the knee performed the IM and the BT. For IM, we calculated the ratio of the knee mean flexor/extensor peak torque (H/Q ratio) for 60°/s and 120°/s, and BT performance was measured in seconds. We classified the IM (<0.6 H/Q ratio) and the BT (leg difference ≥4 s) as binary results according to the literature. We calculated the sensitivity and specificity, which we compared with the Chi-Square test, and the 95% confidence intervals (CI). A p-value of ≤0.05 is considered significant. (3) Results: The sensitivity for the BT was 0.89, 95% CI [0.67, 0.99], and the specificity was 0.52 [0.30, 0.74]. For the IM, the sensitivity was 0.14 [0.03, 0.36] for 60°/s and 0.05 [0.00, 0.24] for 120°/s, and the specificity was 0.70 [0.46, 0.88] for 60°/s and 0.90 [0.68, 0.99] for 120°/s. The results of the Chi-Square tests were significant for the BT (χ2 (1) = 6.17, p = 0.01) but not for the IM (60°/s: χ2 (1) = 0.70, p = 0.40; 120°/s: χ2 (1) = 0.00, p = 0.97). (4) Conclusions: Patients were more likely to obtain a positive test result for the BT but not for the IM.

Evaluation of the ankle function after Achilles tendon resection: a retrospective clinical study

IntroductionThe Achilles tendon is the strongest tendon in the human body and has the function of plantar ankle flexion. When the tendon is exposed, the peritendineum has been breached and the thick avascular tendon colonized with bacteria, a complete resection of the tendon may be indicated to achieve infection control and facilitate wound closure. The Achilles tendon reconstruction is not mandatory, as the plantar flexion of the ankle joint is assumed by the remaining flexor hallucis longus, flexor digitorum longus and tibialis posterior muscles. Our study aimed to evaluate the impact of Achilles tendon resection without reconstruction on leg function and quality of life.Material and methodsWe retrospectively evaluated all patients who were treated with an Achilles tendon resection between January 2017 and June 2022 in our quaternary institution. After evaluating the data, the patients who survived and were not amputated were contacted for re-evaluation, which included isokinetic strength measurement of both ankle joints, evaluation of the ankle range of motion and collection of several functional scores.ResultsThirty patients were included in the retrospective study, with a mean age of 70.3 years, including 11 women and 19 men. The most frequent cause of the infection was leg ulcer (43.3%), followed by open tendon suture (23.3%). No tendon reconstruction was performed. Fifteen patients could be gained for reevaluation. The average difference in ankle flexion torque on the injured side compared to the healthy side at 30 degrees/second was 57.49% (p = 0.003) and at 120 degrees/second was 53.13% (p = 0.050) while the difference in power was 45.77% (p = 0.025) at 30 degrees/second and 38.08% (p = 0.423) at 120 degrees/second. The follow-up time was between 4 and 49 months and a positive correlation could be determined between the time elapsed from surgery and the ankle joint strength. There was a significant loss of range of motion on the operated side compared to the healthy side: 37.30% for plantar flexion, 24.56% for dorsal extension, 27.79% for pronation and 24.99% for supination. The average Lepillhati Score was 68.33, while the average American Orthopedic Foot and Ankle Score was 74.53.ConclusionThe complete Achilles tendon resection leaves the patient with satisfactory leg function and an almost normal gait. Especially in elderly, multimorbid patients, straightforward tendon resection and wound closure provide fast infection control with acceptable long-term results. Further prospective studies should compare the ankle function and gait in patients with and without Achilles tendon reconstruction after complete resection.

Molecular and clinical effects of aromatase inhibitor therapy on skeletal muscle function in early-stage breast cancer

We evaluated biochemical changes in skeletal muscle of women with breast cancer initiating aromatase inhibitors (AI), including oxidation of ryanodine receptor RyR1 and loss of stabilizing protein calstabin1, and detailed measures of muscle function. Fifteen postmenopausal women with stage I–III breast cancer planning to initiate AI enrolled. Quadriceps muscle biopsy, dual-energy x-ray absorptiometry, isokinetic dynamometry, Short Physical Performance Battery, grip strength, 6-min walk, patient-reported outcomes, and serologic measures of bone turnover were assessed before and after 6 months of AI. Post-AI exposure, oxidation of RyR1 significantly increased (0.23 ± 0.37 vs. 0.88 ± 0.80, p < 0.001) and RyR1-bound calstabin1 significantly decreased (1.69 ± 1.53 vs. 0.74 ± 0.85, p < 0.001), consistent with dysfunctional calcium channels in skeletal muscle. Grip strength significantly decreased at 6 months. No significant differences were seen in isokinetic dynamometry measures of muscle contractility, fatigue resistance, or muscle recovery post-AI exposure. However, there was significant correlation between oxidation of RyR1 with muscle power (r = 0.60, p = 0.02) and muscle fatigue (r = 0.57, p = 0.03). Estrogen deprivation therapy for breast cancer resulted in maladaptive changes in skeletal muscle, consistent with the biochemical signature of dysfunctional RyR1 calcium channels. Future studies will evaluate longer trajectories of muscle function change and include other high bone turnover states, such as bone metastases.

Reliability and validity of new isokinetic strength assessment for rotator cuff muscles in a muscle architecture-based position.

Isokinetic strength assessment of the rotator cuff muscle is frequently applied in a variety of shoulder postures, but none of these consider muscular architecture, which is one of the most important aspects of improving strength development. This study aimed to examine the test and retest reliability and validity of the muscle architecture-based position (MABP), which is 25° abduction and 20° external rotation, in healthy subjects to be able to select a better isokinetic assessment position for shoulder rotator cuff muscles. A total of 54 healthy males with a mean age of 21.0 ± 1.2 years and mean body mass index of 22.8 ± 1.7 kg/m2 completed an isokinetic measurement session. All of the tests were performed on an IsoMed 2000 isokinetic dynamometer concentrically and eccentrically for both upper limbs at 60°/s angular velocity. All of the participants completed 3 measurement sessions: the first represented the isokinetic testing and was performed in the scapular neutral position (SNP) (45° shoulder flexion and abduction), the second represented the MABP (25° abduction and 20° ER) for shoulder rotator cuff muscles, and the third represented the test and retest of the MABP. The correlations between the 2 techniques for assessing concurrent validity ranged from 0.908 to 0.994. The values obtained from the MABP were higher than those obtained in the SNP. There was no systematic bias for any measurements between the MABP and the retest of the MABP (p > 0.05). The intraclass correlation coefficients representing the test and retest reliability results for each variable measured with the MABP was higher than 0.98 and this value was considered as excellent reliability. In conclusion, the MABP can be used to assess the isokinetic strength of the rotator cuff muscles safely and confidently, with increased quantities of force being released and measurement at optimal muscle tension.

MYOGENIC CONTRIBUTORS TO PHYSICAL FUNCTION IN OLDER ADULTS WITH SYMPTOMATIC KNEE OSTEOARTHRITIS

Abstract Knee osteoarthritis (OA) is a leading cause of mobility disability among middle-aged and older adults, and contributes to significant global disease burden. The impact of knee OA on physical function varies widely across individuals, and the factors contributing to this heterogeneity are poorly understood. Recent compelling research suggests that myogenic factors, including muscle quality (MQ), may underly symptoms in knee OA. While MQ is gaining attention in aging research, the role of MQ on functional outcomes in persons with knee OA remains unknown. This pilot study examined morphological and neuromuscular biomarkers of MQ among adults aged 50 years and older (N=44) who met clinical criteria for symptomatic knee OA. Physical performance was assessed using the Short Physical Performance Battery (SPPB). MQ was quantified using B-mode ultrasound (echo intensity) and isokinetic strength measures (force/body mass). Associations between MQ and physical performance were determined, with consideration for clinical pain, age, sex, and body mass index. Pearson correlation analysis indicated SPPB scores were associated with clinical pain, strength, and MQ (r values ranged -.42 – 0.60, p’s&amp;lt; 0.05). Multivariable backward stepwise linear regression analysis demonstrated that MQ biomarkers contributed 39% to variance for SPPB score independent of clinical pain and strength, after adjustment for age, sex, and BMI (b’s = -0.32 – 0.45; p’s &amp;lt; 0.05). MQ is an important consideration for physical function in older adults with chronic knee OA pain, regardless of pain severity, and represents a potentially potent treatment target for disability prevention.

Conservative treatment outcome for Achilles tendon re-rupture occurring in the subacute phase after primary repair.

Until now, a treatment protocol for Achilles tendon re-rupture (ATRR) occurring in the postoperative period 5-12weeks following primary Achilles tendon repair has not been established. We refer to this time frame as the subacute postoperative phase, and the objective of this study was to assess the efficacy of conservative treatment for subacute ATRR in this phase. We conducted a retrospective review of 390 cases (385 patients) who had undergone primary Achilles tendon repair using the 4-strand Krachow method between January 2010 and August 2021. All patients were subjected to more than 12months of follow-up and were categorized into two groups based on the presence of subacute ATRR: Group 1 comprised 370 cases without ATRR, while Group 2 comprised 20 cases with ATRR. Following confirmation of ATRR, we immediately applied a below-knee cast in an ankle plantar flexed position (25°-30°), followed by bracing according to the same rehabilitation plan used for the primary repair. After administering conservative treatment to the patients with ATRR, we compared several outcome parameters between the two groups, including isokinetic plantar flexion power measured using a dynamometer, time required for a single heel raise (t-SHR), time needed for ten repetitive SHRs (t-SHR10), Achilles Tendon Total Rupture Score (ATRS), and Foot and Ankle Ability Measure (FAAM) scores. The baseline timepoints for Groups 1 and 2 were the dates of the primary repair and the re-injury event. After primary Achilles tendon repair, subacute ATRR occurred in 5.1% of patients. There were no significant differences between the groups in terms of t-SHR and t-SHR10 (P = 0.281, 0.486). Similarly, the isokinetic dynamometer measurements revealed no significant differences in peak torque for plantar flexion at angular velocities of 30°/s and 120°/s, both in absolute values and as a percentage of the contralateral side, between the groups (P > 0.05 for each). However, ATRSs were significantly lower in Group 2 compared to Group 1 before 6months (P < 0.05), as were FAAM-Activities of Daily Living scores at 6months (P < 0.05). After 12months, there were no significant differences in these scores between the two groups (both P > 0.05). Conservative treatment for subacute ATRR following primary Achilles tendon repair yields clinical outcomes comparable to those without ATRR. Therefore, we recommend that surgeons consider relying on the patient's natural healing capabilities rather than opting for aggressive surgical interventions, as expediting such operations may be unnecessary for subacute injuries.

Investigating the relationship between pain level and grip and wrist muscles strength in individuals with lateral epicondylitis: is pain a barrier to strength assessment?

This study was carried out to examine the relationship between rest, activity, and nighttime pain and grip and isokinetic muscle strength of the wrist muscles in individuals with lateral epicondylitis. Fifty-six sedentary individuals aged between 18 and 65years diagnosed with unilateral lateral epicondylitis volunteered to participate in the study. The level of rest, activity, and nighttime pain was evaluated with visual analog scale (VAS). The grip strengths of both arms were evaluated by averaging a maximum of three grip strength measurements using a hand dynamometer. The strength of both wrist flexor and extensor muscles were evaluated with isokinetic dynamometer at angular velocities of 60 and 180°/s with five and 15 concentric repetitions respectively. There was no significant relationship found between the affected side's grip strength and isokinetic muscle strength with rest, activity and nighttime pain (all P > 0.05). However, there was a difference observed between the affected and unaffected side in grip strength and isokinetic strength measurements of all wrist muscles (all P < 0.05); the unaffected side values were found to be higher. The result of this study found no correlation between the stated level of pain and the true muscle strength in the affected hand. In line with these findings, we think that assessments involving strength can be made in other musculoskeletal problems where pain is present. However, the findings may not reflect the true muscle strength which will tend to be underrated.