Isometric Quadriceps Strength Research Articles

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.

#596 The Borg Scale—efficient and safe for exercise prescription in self-administered balance and strength exercise in patients with CKD

Abstract Background and Aims With the continued rise in chronic kidney disease (CKD), there is a critical need for sustainable, home-based exercise interventions. While supervised, centre-based exercise improves physical performance in CKD patients, unsupervised, self-administered exercise poses challenges in ensuring adherence, safety, and efficacy. This study investigates the Borg Rating of Perceived Exertion (RPE) scale, a subjective measure of exertion, as a method for prescribing and monitoring the intensity of balance and strength exercise in non-dialysis dependent CKD patients. The aims of this study were: Method This sub study of the RENEXC-trial included 148 patients with CKD stages 3-5, with a mean age of 66 ± 14 years and mean measured GFR of 22 ± 8 ml/min/1.73 m2. Patients were prescribed 90 minutes/week of balance or strength exercise at a Borg RPE of 13-17 (corresponding to an exercise intensity of somewhat hard to very hard), along with 60 minutes/week of endurance exercise. Exercise programs were individually prescribed by a physiotherapist according to randomization and each patient's baseline performance and were performed at home or in a gym according to the patient's preference. Duration and RPE of the performed exercise were reported in an exercise diary. Progress was monitored by the physiotherapist through phone contact, every week for the first three months of the study and every other week for the rest of the study year. The continuous follow up provided motivation and enabled adjustments of the exercise program to maintain the goal RPE, adapt intensity and the weekly duration of exercise. Outcome measures included the Berg Balance Scale (BBS) and Functional Reach Test (FRT), the 30-second sit-to-stand test (30STS) and isometric quadriceps strength (IQS). Balance and strength measures were evaluated at baseline and after 12 months of exercise. Previous publications of the RENEXC-trial showed no difference between patients who performed balance exercise and patients who performed strength exercise; therefore, this sub-study analysed all included patients as one group. Results Of 148 participants, 112 completed the study. At 12 months, 79% reported performed exercise, with 86% of these patients adhering to the prescribed intensity. The median (25th-75th percentile) exercise intensity was a RPE of 14 (13-15) on the Borg scale, and the median (min-max) exercise duration was 48 (0-241) minutes/week. Only 18% of the patients reached the 90-minute/week target. No exercise-related incidents were reported. Significant improvements were noted in BBS (p = 0.0464), FRT (p = 0.009), 30STS (p = 0.047), and IQS (right/left p = 0.022 / p = 0.049). Conclusion The Borg RPE scale is an effective and safe method for prescribing and monitoring self-administered balance and strength exercise in patients with CKD. Using the Borg scale for prescribing and monitoring exercise intensity during balance and strength exercise resulted in a good level of adherence to the 12-months exercise program and the prescribed exercise intensity. As no exercise related incidents were reported, we conclude that the self-administered exercise was safe to perform. Significant improvements in balance and strength were observed with a moderate to high exercise intensity prescription within a wide range of performed weekly duration of exercise, suggesting the Borg scale's value in exercise prescription in both well- and deconditioned patients with CKD. These findings show that the integration of the Borg scale into routine exercise prescription in people with CKD can promote patient autonomy and efficient resource utilization in healthcare.

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.

Psychological Factors Are Related to Neuromuscular Asymmetries After Anterior Cruciate Ligament Reconstruction.

After an anterior cruciate ligament reconstruction (ACLR), only 47% of military members return to full duty, possibly due to persistent neuromuscular asymmetries. Psychological factors may also contribute to reduced return to duty in military members. Psychological factors and time since surgery would be associated negatively with neuromuscular asymmetries, asymmetries would be greater in cadets postsurgery when compared with healthy controls, and asymmetries would be greater at earlier timepoints after ACLR. Case control. Level 4. This study examined the relationship between psychological factors and time since surgery with neuromuscular asymmetry, compared neuromuscular asymmetries between cadets with and without a history of ACLR, and explored differences in neuromuscular asymmetries at different timepoints in cadets with a history of ACLR. A total of 37 cadets post-ACLR (18.3 ± 9 months) and 28 controls participated. Psychological factors were assessed using the Tampa Scale of Kinesiophobia and Anterior Cruciate Ligament-Return to Sport after Injury scale (ACL-RSI). Participants performed a drop-jump landing, joint positioning sense (JPS), and isometric quadriceps strength testing. Peak vertical ground-reaction forces (vGRF), absolute angle of replication, peak quadriceps torque, rate of torque development (RTD), and RTD time torque interval 200 ms (TTI200) were analyzed. The ACL-RSI score was significantly related to limb symmetry index (LSI) peak quadriceps torque (r = 0.617, P < 0.01), LSI RTD (r = 0.367, P = 0.05), and LSI TTI200 (r = 0.0489, P < 0.01), but not time since surgery, JPS, or LSI peak vGRF. Cadets with a history of ACLR had significantly lesser ACL-RSI scores and greater asymmetries compared with controls. Reduced psychological readiness was associated with increased neuromuscular asymmetries after ACLR. Clinicians should assess psychological readiness during rehabilitation after ACLR.

Effect of early weight bearing program with conventional physiotherapy on functional outcomes in surgically treated proximal tibia fracture: a pilot randomized controlled trial.

Patients are often instructed to avoid weight bearing on the proximal tibia for 6 - 12 weeks post-surgery to avoid fracture fixation failure. However, delayed weight bearing leads to delayed mobility, causing difficulties in daily activities; problems such as pain, limited knee ROM, reduced quadriceps muscle strength, and impaired functional outcomes are reported in long-term follow-up. This study primarily aimed to evaluate the feasibility and explore the effect size. The secondary aim was to determine the effectiveness of early weight bearing along with conventional physiotherapy on functional outcomes. A single-blinded pilot randomized controlled trial with 30 participants with proximal tibia type I, II, and III fractures were included; they were randomized using computer-based software. Seven patients were lost to follow-up. Group I received early weight bearing along with conventional physiotherapy whereas Group II received restricted weight bearing along with conventional physiotherapy. Assessments were made on post-operative day 3 (POD-03), at discharge, at 6 weeks, and at 12 weeks. Radiographs were recorded immediately after the operation, at discharge, and at 12 weeks. A full-scale RCT is feasible with an effect size between 0.3 - 0.7. A statistically significant difference (p < 0.05) was found within both groups 12 weeks post-surgery in all outcome measures; the difference was more prominent in the intervention group. A statistically significant difference (p < 0.05) was found between both the groups post-12 weeks in all outcome measures except quadriceps isometric muscle strength. A full-scale RCT for early weight bearing along with conventional physiotherapy for patients operated for Type I, II, and III proximal tibia fracture is feasible. Early weight bearing along with conventional physiotherapy could have a positive effect on reducing patient's pain perception and increasing knee joint mobility, quadriceps isometric muscle strength, knee function, and quality of life without any adverse effects. ClinicalTrialsRegistry.gov (CTRI/2022/10/046797).

Validity and Reliability of Handheld Dynamometry to Assess Isometric Hamstrings and Quadriceps Strength at Varying Muscle Lengths.

The hamstrings are the most commonly injured muscle in sports and are especially injury prone in lengthened positions. Measuring knee muscle strength in such positions could be relevant to establish injury risk. Handheld dynamometry has been shown to be a valid, reliable, and practical tool to measure isometric muscle strength clinically. The aim of this study was to assess the validity and reliability of the assessment of isometric knee muscle strength with a handheld dynamometer (HHD) at various muscle lengths, by modifying the hip and knee angles during testing. Concurrent validity and test-retest reliability. Thirty young healthy participants were recruited. Hamstring and quadriceps isometric strength was measured with a HHD and with an isokinetic dynamometer, over 2 testing sessions, in a randomized order. Isometric strength was measured on the right lower limb in 6 different positions, with the hip at either 0° or 80° of flexion and the knee at either 30°, 60°, or 90° of flexion. Pearson and Spearman correlations were used to assess the validity, and intraclass correlation coefficients were calculated to establish the test-retest reliability of the HHD. Good to excellent reliability and moderate to high validity were found in all the tested muscle length positions, except for the hamstrings in a seated position with the knee extended at 30°. The use of a HHD is supported in the clinical setting to measure knee muscle strength at varying muscle lengths in healthy adults, but not for the hamstrings in a lengthened position (hip flexed and knee extended). These results will have to be confirmed in sport-specific populations.

Relationship between intended force and actual force: comparison between athletes and non-athletes.

This cross-sectional study aimed to investigate whether athletes (ATHL) and non-athletes (NON-ATHL) individuals had similar accuracy in matching intended to actual force during ballistic (BAL) and tonic (TON) isometric contractions. In this cross-sectional study, the subjects were divided into ATHL (n=20; 22.4 ± 2.3 yrs; 73.2±15.7kg; 1.76 ± 0.08 m) and NON-ATHL (n=20; 24.6 ± 2.4 yrs; 68.2 ± 15.0kg; 1.73±0.1 m) groups. The isometric quadriceps strength was measured with a load cell applied to a custom-built chair. For each condition, subjects performed at first three maximal voluntary isometric contractions (MVIC) as reference. Then, subjects had to match three intended force intensities expressed in percentage of the MVIC (i.e., 25%, 50%, and 75%) without any external feedback. Subjects performed three trials for each force intensity. The accuracy (AC) was calculated as the absolute difference in percentage between the intended and the actual force. A Likert scale was administered for each trial to assess the subjective matching between the intended and the actual force. Statistical analysis showed that the ATHL group was more accurate (p<0.001) than the NON-ATHL group. In contrast, the AC (p<0.001) was lower when the force intensities increased independently from the group. Moreover, significantly higher AC (p<0.001) and lower aggregate Likert scores (p<0.001) were found in BAL than TON conditions. These results suggest that (i) sports practice could enhance muscle recruitment strategies by increasing the AC in the isometric task; (ii) differences between intended and actual force appeared to be intensity-dependent with lower AC at high force intensities; (iii) different control systems act in modulating BAL and TON contractions.

The Association between the Level of Ankle-Brachial Index and the Risk of Poor Physical Function in Patients with Cardiovascular Disease.

The progression of atherosclerosis and decline in physical function are poor prognostic factors in patients with cardiovascular disease (CVD). The ankle-brachial index (ABI) is a widely used indicator of the degree of progression of atherosclerosis, which may be used to identify patients with CVD who are at risk of poor physical function. This study examined the association between ABI and poor physical function in patients with CVD. We reviewed the data of patients with CVD who completed the ABI assessment and physical function tests (6-min walking distance, gait speed, quadriceps isometric strength, and short physical performance battery). Patients were divided into five categories according to the level of ABI, and the association between ABI and poor physical function was examined using multiple logistic regression analysis. Additionally, restricted cubic splines were used to examine the nonlinear association between ABI and physical function. A total of 2982 patients (median [interquartile range] age: 71[62-78] years, 65.8% males) were included in this study. Using an ABI range of 1.11-1.20 as a reference, logistic regression analysis showed that ABI ≤ 1.10 was associated with poor physical function. The restricted cubic spline analysis showed that all physical functions increased with an increase in ABI level. The increase in physical function plateaued at an ABI level of approximately 1.1. ABI may be used to identify patients with poor physical function. ABI levels below 1.1 are potentially associated with poor physical function in patients with CVD.

Physiotherapeutic Intervention Techniques for Knee Osteoarthritis: A Systematic Review.

Globally, knee osteoarthritis (KOA) is the leading cause of disability. The most prevalent complaints associated with KOA are knee pain, joint stiffness, and weakness in the muscles of the lower limbs. These symptoms impede movement and result in functional limitations. As a result, people with KOA have a lower quality of life. For all patient groups with knee OA, an effective rehabilitation program focuses on improving knee range of motion, isometric quadriceps strength, and productivity level while reducing discomfort. The American College of Rheumatology (ACR) categorization criteria for KOA, research on KOA physiotherapy, and reviews covering various physical therapy interventions, including exercise, physical modalities, and patient education, were used to narrow down the pool of 180 systematic reviews to 15 articles. Google Scholar, PubMed, the Cochrane Library, and EMBASE were the databases that were used. The following keyword combinations were included in our search: KOA and physiotherapy or interventions or exercises, strengthening and stretching, concentric and eccentric training. Through our analysis, we identified a few methods that, in addition to standard therapy, could be used in clinical settings for people with osteoarthritis in the knee. It has been shown that Mulligan, Pilates, Kinesiotaping, Aquatic Therapy, and other current therapies are effective. The study employed a broad range of results. This review concludes that rather than relying solely on conventional therapy, it is preferable to combine a number of the most current physiotherapy techniques with it.

Knee Offloading by Patients During Walking and Running After Meniscectomy.

Changes in knee loading have been reported after meniscectomy. Knee loading has previously been assessed during jogging and treadmill running rather than overground running, which could give altered results. The purpose of this study was to evaluate knee function during overground running and walking after meniscectomy. It was hypothesized that the affected limb would demonstrate higher external knee adduction moment, lower knee flexion moment (KFM), and lower knee rotation moment (KRM) compared with the contralateral limb and with healthy individuals. Controlled laboratory study. Kinematic and kinetic data were collected during running and walking in individuals after a meniscectomy and healthy individuals. Total knee joint moments (TKJM) were calculated from the sagittal, frontal, and transverse knee moments. Isometric quadriceps strength, perceived knee function, and kinesiophobia were also assessed. A mixed linear model compared differences between the affected leg, the contralateral leg, and the healthy leg. Data were collected on 20 healthy individuals and 30 individuals after a meniscectomy (mean ± SD, 5.7 ± 2.9 months postsurgery), with 12, 16, and 2 individuals who had medial, lateral, and both medial and lateral meniscectomy, respectively. The affected limb demonstrated lower TKJM (P < .001), KFM (P = .004), and KRM (P < .001) during late stance of walking compared with the healthy group. Lower TKJM and KFM were observed during running in the affected limb compared with the contralateral limb and healthy group. No significant differences were observed between contralateral and healthy limbs except for KRM during late stance of walking. Lower quadriceps strength was observed in the affected (P < .001) and contralateral limbs (P = .001) compared with the healthy group. Individuals after a meniscectomy also reported greater kinesiophobia (P = .006) and lower perceived knee function (31.1%; P < .001) compared with the healthy group. After meniscectomy, individuals who sustained a traumatic meniscal injury showed lower TKJM in the affected limb compared with the contralateral limb and healthy individuals. This decrease in TKJM can be attributed to altered knee-loading strategies in the sagittal and transverse planes. Improving movement strategies, quadriceps strength, and kinesiophobia through rehabilitation approaches will allow individuals to load their knee appropriately when returning to sport. NCT03379415 (ClinicalTrials.gov identifier).

Muscle Fiber Cross-Sectional Area Is Associated With Quadriceps Strength and Rate of Torque Development After ACL Injury.

Graham, MC, Thompson, KL, Hawk, GS, Fry, CS, and Noehren, B. Muscle fiber cross-sectional area is associated with quadriceps strength and rate of torque development after ACL injury. J Strength Cond Res XX(X): 000-000, 2023-The purpose of this study was to investigate the relationship between muscle fiber type-specific properties of the vastus lateralis and quadriceps muscle performance in individuals after an anterior cruciate ligament (ACL) tear. 26 subjects (22.0 ± 5.4 years) were included in this cross-sectional study, and all data were collected before ACL reconstruction. Quadriceps peak torque (QPT) and early (0-100 ms) and late (100-200 ms) rate of torque development (RTD) were obtained from maximal voluntary isometric quadriceps strength testing. Muscle fiber cross-sectional area (fCSA) and percent fiber type distribution (FT%) were evaluated through immunohistochemical analysis of a muscle biopsy. Between-limb differences in fiber characteristics were assessed using paired t-tests (with α-level 0.05). Relationships between fiber-specific properties and quadriceps muscle performance were determined using separate multiple linear regression analyses for ACL-injured and noninjured limbs. There were significant differences in fCSA between ACL-injured and noninjured limbs across all fiber types, but no differences in FT%. Type 1 fCSA, type 2a fCSA, and their interaction effect were the explanatory variables with the strongest relationship to all performance outcomes for the ACL-injured limb. The explanatory variables in the ACL-injured limb had a significant relationship to QPT and late RTD, but not early RTD. These findings suggest that QPT and late RTD are more heavily influenced by fCSA than FT% in ACL-injured limbs. This work serves as a foundation for the development of more specific rehabilitation strategies aimed at improving quadriceps muscle function before ACL reconstruction or for individuals electing nonsurgical management.

Hypoxic, blood flow restriction, or eccentric cycling: Which training intervention is the most effective in elderly individuals?

Introduction&#x0D; The global rise in the elderly population is accompanied by an increased incidence of non-communicable diseases, including cancers, cardiovascular conditions, or sarcopenia. Therefore, it becomes crucial to find effective strategies to delay the onset or slow down the progression of these diseases. Hypoxic (HYP), blood flow restriction (BFR), and eccentric (ECC) training are promising modalities to mitigate the effects of aging. However, these training strategies have never been compared. Thus, this study aimed to evaluate whether moderate-intensity intermittent training (MIIT) combined with HYP, BFR, or ECC can induce similar or greater effects in strength and muscle mass in the elderly, compared to traditional cycling training (CON).&#x0D; Methods&#x0D; Fifty-five elderly participants completed a four-week MIIT protocol on cycle ergometers, divided into HYP, BFR, ECC, and CON groups. The HYP group trained under hypoxic conditions (inspired oxygen fraction ~14%), BFR group used occlusion cuffs applied proximally on thighs (~350 mmHg occlusion pressure), ECC group trained with an eccentric cycle-ergometer, and the CON group underwent standard cycling training. The first week consisted of 3 sets of 5 min exercise followed by 5 min rest and an additional set was added each week. All groups maintained a 60-rpm cadence, with intensity set at a 14-perceived exertion level on the 6-20 Borg scale.&#x0D; Strength parameters were assessed via isokinetic tests at angular velocities of 30°/s, 90°/s, and 180°/s, as well as isometric and endurance tests. Endurance strength was calculated as a percentage decrement score during 30 repetitions at 180°/s and the rate of force development was calculated on the isometric test.&#x0D; Muscle-bone cross-sectional area (CSA) was measured by integrating thigh circumference measured using a measuring tape, and anterior and posterior adipose tissue thickness assessed with a B-mode ultrasound.&#x0D; Results&#x0D; Post-training, all groups showed increased isometric quadriceps strength (14 ± 15%, p &lt; 0.001) and strength at all angular velocities: 18 ± 17% and 15 ± 21% (30°/s), 17 ± 20% and 20 ± 26% (90°/s), 10 ± 14% and 10 ± 16% (180°/s) for quadriceps and hamstrings respectively, all P &lt; 0.001. No significant group interaction effects were noted, except for hamstring strength at 30°/s (P = 0.038), with no improvements in the ECC group. No changes in the rate of force development or dynamic endurance post-training were noted. Thigh circumference increased (1 ± 2%, p = 0.008), without difference between training modalities.&#x0D; No significant variations in adipose tissue thickness or muscle-bone CSA occurred. The ECC group had higher training intensity (173.2 ± 7.5 W) than HYP (169.6 ± 9.8 W), BFR (169.9 ± 11.6 W), and CON (169.6 ± 8.4 W) groups (p &lt; 0.001). Training heart rate was lower in ECC (104.5 ± 6.6 bpm) compared to BFR (117.5 ± 10.5 bpm; p = 0.007) and CON (122.2 ± 12.3 bpm; p = 0.001), but similar to HYP (112.2 ± 9.4 bpm).&#x0D; Discussion/Conclusion&#x0D; MIIT, regardless of modality, effectively improves muscle strength in the elderly. Unexpectedly, no single training method was superior. Power output reduction has been proposed as an advantage of HYP and BFR modalities but was not observed in the present study. These results advocate for a personalized approach to training prescriptions, considering individual preferences and health conditions. Future research should explore longer training durations and impacts on other health outcomes such as cardiovascular and respiratory health.

Concurrent activation potentiation improves lower-limb maximal strength but not dynamic balance control in rugby players.

Concurrent activation potentiation (CAP) increases athletic performance by activating muscles not involved in the performed activity. Among the CAP strategies, jaw clenching is the most practical to implement in sports contexts. Muscle strength and balance control are essential among rugby players to cope tackles. Besides combat sports, mouthguard has become mandatory also in rugby. Therefore, this study aimed to understand whether mouthguard jaw-clenching could improve rugby players' dynamic balance and quadriceps isometric strength. Thirteen rugby players were tested under maximal-bite (MB) and no-bite (NB) conditions. During standing balance tests, an electro-actuated platform with a force plate screwed on it allowed for the perturbation of the support base of the rugby players. A verbal signal warned the subject that the perturbation was coming, mentally recalling an in-field expected collision. In the first 2.5s window after the perturbation, the center of pressure (CoP) displacement and mean velocity were measured. The first peak, the maximal oscillations, and the standard deviation of the anterior-posterior CoP trajectory were calculated within the same time window. In the isometric leg-extension test, a custom-built chair instrumented with a uni-axial load cell allowed to collect the maximal strength and rate of force development (RFD). Mouthguard jaw-clenching did not affect CoP-related parameters but increased maximal strength (p < 0.05) and RFD (0-50ms: p < 0.01; 50-100ms: p < 0.001; 100-150ms: p < 0.05) in the isometric leg-extension test. Mouthguard jaw-clenching alone could be useful to increase lower-limb maximal isometric strength and RFD but did not improve dynamic balance performance in a sport-oriented postural balance test.

Different roles of circulating and intramuscular GDF15 as markers of skeletal muscle health.

Growth Differentiation Factor 15 (GDF15) is a mitokine expressed in response to various stresses whose circulating levels increase with age and are associated with numerous pathological conditions, including muscle wasting and sarcopenia. However, the use of circulating GDF15 (c-GDF15) as a biomarker of sarcopenia is still debated. Moreover, the role of GDF15 intracellular precursor, pro-GDF15, in human skeletal muscle (SM-GDF15) is not totally understood. In order to clarify these points, the association of both forms of GDF15 with parameters of muscle strength, body composition, metabolism and inflammation was investigated. the levels of c-GDF15 and SM-GDF15 were evaluated in plasma and muscle biopsies, respectively, of healthy subjects (HS) and patients with lower limb mobility impairment (LLMI), either young (<40 years-old) or old (>70 years-old). Other parameters included in the analysis were Isometric Quadriceps Strength (IQS), BMI, lean and fat mass percentage, Vastus lateralis thickness, as well as circulating levels of Adiponectin, Leptin, Resistin, IGF-1, Insulin, IL6, IL15 and c-PLIN2. Principal Component Analysis (PCA), Canonical Discriminant Analysis (CDA) and Receiving Operating Characteristics (ROC) analysis were performed. c-GDF15 but not SM-GDF15 levels resulted associated with decreased IQS and IGF-1 levels in both HS and LLMI, while only in LLMI associated with increased levels of Resistin. Moreover, in LLMI both c-GDF15 and SM-GDF15 levels were associated with IL-6 levels, but interestingly SM-GDF15 is lower in LLMI with respect to HS. Furthermore, a discrimination of the four groups of subjects based on these parameters was possible with PCA and CDA. In particular HS, LLMI over 70 years or under 40 years of age were discriminated based on SM-GDF15, c-GDF15 and Insulin levels, respectively. our data support the idea that c-GDF15 level could be used as a biomarker of decreased muscle mass and strength. Moreover, it is suggested that c-GDF15 has a different diagnostic significance with respect to SM-GDF15, which is likely linked to a healthy and active state.

Transcutaneous Electrical Nerve Stimulation Provides Early Recovery from Arthrogenic Muscle Inhibition Post-Anterior Cruciate Ligament Reconstruction

Abstract Background: Quadriceps weakness that ensues anterior cruciate ligament (ACL) reconstruction, a common procedure done in sportspersons, is a hindrance in the active rehabilitation and delays return to sport. This weakness of quadriceps muscle is a complex neural phenomenon ascribed to arthrogenic muscle inhibition (AMI). Purpose: The purpose of the study was to assess the effectiveness of transcutaneous electrical nerve stimulation (TENS) in AMI post-ACL reconstruction (ACLR). Methods: A prospective randomized study involving 60 patients with isolated ACL injury above 18 years of age were included. Patients with osteoarthritis knee, multiligament injury, previous knee surgery, and inflammatory knee pathology were excluded from the study. Patients were divided into Groups A and B (n = 30, each). Group A received TENS therapy with exercises and ice packs, whereas Group B received only exercise and ice packs post-ACLR. All patients were assessed subjectively using Visual Analog Scale score for pain, Lysholm, and IKDC score for functional outcome pre and postoperatively on day 2, 1 month, 3 months, 6 months, and 1 year. Objective assessment was done by measuring thigh girth (10 cm above knee joint line) and isometric quadriceps strength (using David Biofeedback Strength Evaluation Machine) pre and postoperatively at day 2, 1 week, 2 weeks, 1 month, 3 months, 6 months, and 1 year. Results: Pain decreased in both groups at 1 month, 3 months, and 6 months, but there was significantly lower pain in Group A in comparison to Group B at 1 month (P = 0.003), 3 months (P = 0.001), and 6 months (P ≤ 0.0001). There was no pain at 1 year in both the groups. Lysholm score improved in both groups, but there was statistically significantly better Lysholm score in Group A in comparison to Group B at each follow-up. IKDC score improved in both groups, but the improvement in Group A was significantly higher than Group B at each follow-up. No significant difference in mean thigh girth was observed. Mean quadriceps strength was similar in both groups except at 6 months where Group A was better than Group B (&lt;0.001). Conclusion: Addition of TENS in ACLR rehabilitation decreases pain and provides better clinical outcome.

Leg strength and incidence of heart failure in patients with acute coronary syndrome.

The risk of developing heart failure (HF) after acute coronary syndrome (ACS) remains high. It is unclear whether skeletal muscle strength, in addition to existing risk factors, is a predictor for developing HF after ACS. We aimed to clarify the relationship between quadriceps isometric strength (QIS), a skeletal muscle strength indicator, and the risk of developing HF in patients with ACS. We included 1053 patients with ACS without a prior HF or complications of HF during hospitalization. The median (interquartile range) age was 67 (57-74) years. The patients were classified into two groups-high and low QIS-using the sex-specific median QIS. The endpoint was HF admissions. During a mean follow-up period of 4.4 ± 3.7 years, 75 (7.1%) HF admissions were observed. After multivariate adjustment, a high QIS was associated with a lower risk of HF [hazard ratio: 0.52, 95% confidence interval (CI): 0.32-0.87]. Hazard ratio (95% CI) per 5% body weight increment increase of QIS for HF incidents was 0.87 (0.80-0.95). Even when competing risks of death were taken into account, the results did not change. The inclusion of QIS was associated with increases in net reclassification improvement (0.26; 95% CI: 0.002-0.52) and an integrated discrimination index (0.01; 95% CI: 0.004-0.02) for HF. The present study showed that a higher level of QIS was strongly associated with a lower risk of developing HF after ACS. These findings suggest that skeletal muscle strength could be one of the factors contributing to the risk of developing HF after ACS.

Which Tests Predict 6-Month Isokinetic Quadriceps Strength After ACL Reconstruction? An Examination of Isometric Quadriceps Strength and Functional Tests at 3 Months.

Restoration of quadriceps strength after anterior ligament reconstruction (ACLR) is a persistent challenge for patients and clinicians. Inadequate recovery of quadriceps strength has been linked to increase risk of re-injury. Developing methods of early identification of strength deficits is essential to allow clinicians to provide more individualized interventions early in the rehabilitation process. To determine whether 3-month isometric quadriceps strength, the Y-Balance Test (YBT), and the anterior step-down test are predictive of isokinetic quadriceps strength at six months in adolescents after ACLR. Retrospective cohort. Thirty-six adolescent patients with primary ACLR (58% female, 36% with concomitant meniscal repair, age: 15.7 ± 1.6 years). At three months post-operative, isometric quadriceps strength via isokinetic dynamometer, YBT-Lower Quarter, and anterior step-down tests were completed. At six months post-operative, an isokinetic knee strength assessment was completed. Regression analysis was used to evaluate the predictive relationship between 3-month isometric tests and 6-month isokinetic knee extension tests. Three-month post operative isometric quadriceps peak torque predicted isokinetic quadriceps peak torque at 6 months, F(1,34) = 19.61, p <0.001. Three-month isometric quadriceps peak torque accounted for 36.6% of the variance in normalized isokinetic quadriceps peak torque at 6 months with adjusted R2 = 34.7%. Including YBT anterior reach (β = 0.157, p = 0.318) in regression added 1.9% of variance when predicting 6-month isokinetic quadriceps peak torque, F (2,33) = 10.32, p <0.001, R2 = 0.385, ΔR2 = 0.019. At three months post-ACLR, isometric strength testing appears more optimal than other functional tests in predicting isokinetic quadriceps peak torque in later stages of rehabilitation for adolescents. Clinicians should use tests at three months that measure quadriceps strength if aiming to predict isokinetic quadriceps peak torque at six months post-ACLR, rather than using functional tests such as the YBT-LQ or anterior step-down. Level 3.

Effects of a Perioperative Blood Flow Restriction Therapy Program on Early Quadriceps Strength and Patient-Reported Outcomes After Anterior Cruciate Ligament Reconstruction.

Quadriceps muscle atrophy remains a limiting factor in returning to activity after anterior cruciate ligament reconstruction (ACLR). Blood flow restriction (BFR) therapy may accelerate quadriceps strengthening in the perioperative period. To evaluate postoperative isometric quadriceps strength in patients who underwent ACLR with a perioperative BFR program. Randomized controlled trial; Level of evidence, 1. Patients indicated for ACLR were randomized into 2 groups, BFR and control, at their initial clinic visit. All patients underwent 2 weeks of prehabilitation preoperatively, with the BFR group performing exercises with a pneumatic cuff set to 80% limb occlusion pressure placed over the proximal thigh. All patients also underwent a standardized postoperative 12-week physical therapy protocol, with the BFR group using pneumatic cuffs during exercise. Quadriceps strength was measured as peak and mean torque during seated leg extension and presented as quadriceps index (percentage vs healthy limb). Patient-reported outcomes (PROs), knee range of motion, and quadriceps circumference were also gathered at 6 weeks, 3 months, and 6 months postoperatively, and adverse effects were recorded. Included were 46 patients, 22 in the BFR group (mean age, 25.4 ± 10.6 years) and 24 in the control group (mean age, 27.5 ± 12.0 years). At 6 weeks postoperatively, the BFR group demonstrated significantly greater strength compared with the controls (quadriceps index: 57% ± 24% vs 40% ± 18%; P = .029), and the BFR group had significantly better Patient-Reported Outcomes Measurement Information System-Physical Function (42.69 ± 5.64 vs 39.20 ± 5.51; P = .001) and International Knee Documentation Committee (58.22 ± 7.64 vs 47.05 ± 13.50; P = .011) scores. At 6 weeks postoperatively, controls demonstrated a significant drop in the peak torque generation of the operative versus nonoperative leg. There were no significant differences in strength or PROs at 3 or 6 months postoperatively. Three patients elected to drop out of the BFR group secondary to cuff intolerance during exercise; otherwise, no other severe adverse events were reported. Integrating BFR into perioperative physical therapy protocols led to improved strength and increased PROs at 6 weeks after ACLR. No differences in strength or PROs were found at 3 and 6 months between the 2 groups. NCT04374968 (ClinicalTrials.gov identifier).

Strength symmetry after autograft anterior cruciate ligament reconstruction

ObjectiveTo compare postoperative isometric quadriceps strength indices (QI%) and hamstring strength limb symmetry indices (HI%) between partial thickness quadriceps tendon (pQT), full thickness quadriceps tendon (fQT), and bone-patellar-tendon bone (BPTB) autograft anterior cruciate ligament reconstruction (ACLR). MethodsPatients with primary ACLR with pQT, fQT, or BPTB autograft with the documentation of quantitative postoperative strength assessments between 2016 and 2021 were included. Isometric Biodex data, including QI% and HI% (calculated as the percentage of involved to uninvolved limb strength) were collected between 5 and 8 months and between 9 and 15 months postoperatively. ResultsIn total, 124 and 51 patients had 5–8- and 9–15-month follow-up strength data, respectively. No significant difference was detected between groups for sex. However, patients undergoing fQT were found to be older than those undergoing BPTB (24.6±7 vs 20.2±5; ​p = 0.01). There were no significant differences in the number of concomitant meniscus repairs between the groups (pQT vs. fQT vs. BPTB). No significant differences were detected in median (min–max) QI% between pQT, fQT, and BPTB 5–8 months [87 ​% (44%–130 ​%), 84 ​% (44%–110 ​%), 82 ​% (37%–110 ​%) or 9–15 months [89 ​% (50%–110 ​%), 89 ​% (67%–110 ​%), and 90 ​% (74%–140 ​%)] postoperatively. Similarly, no differences were detected in median HI% between the groups 5–8 months or 9–15 months postoperatively. ConclusionThe study was unable to detect differences in the recovery of quadriceps strength between patients undergoing ACLR with pQT, fQT, and BPTB autografts at 5–8 months and 9–15-months postoperatively. Level of evidenceIII.

Association of affected and non-affected side ability with postoperative outcomes in patients undergoing total hip arthroplasty.

Although several reports have examined the association between preoperative function and postoperative outcomes in patients undergoing total hip arthroplasty (THA), it is unclear whether the ability of the affected or non-affected side particularly impacts on outcomes. We aimed to investigate the association between affected and non-affected side ability and walking independence. We prospectively enrolled 721 consecutive patients who underwent THA. Preoperatively, quadriceps isometric strength (QIS) and one-leg standing time (OLST) were measured. The endpoints were walking independence within 3, 5, 7, 10, and 14 days postoperatively. The associations between preoperative abilities and outcomes were examined using multivariate Cox hazard model, and the area under the curves (AUCs) for outcomes were compared. We analysed 540 patients after excluding patients who met the exclusion criteria. Both affected and non-affected QIS predicted walking independence within 3 (p = 0.006 and 0.001, respectively), 5, 7, 10, and 14 (both p < 0.001) days postoperatively. For OLST, only the affected side did not predict walking independence within 3 days postoperatively (p = 0.154 and 0.012, respectively), and both sides did at days 5 (p = 0.019 and <0.001, respectively), 7, 10, and 14 (both p < 0.001). The AUCs of the non-affected side ability for walking independence were significantly greater than those of the affected side on postoperative days 3 (0.66 vs. 0.73; p = 0.021) and 5 (0.67 vs. 0.71; p = 0.040), with no significant difference after day 7. Both sides abilities were associated with walking independence after THA, but non-affected side was found to be particularly crucial for early walking independence.