Quadriceps Activation Failure Research Articles

The Effects of Disinhibitory Transcutaneous Electrical Nerve Stimulation on Contralateral Quadriceps Activation in Osteoarthritic Patients

Bilateral quadriceps activation failure has been reported following unilateral knee injuries, suggesting that muscle inhibition may be modulated by central nervous system processes. Transcutaneous electrical nerve stimulation (TENS) applied to the injured knee has been reported to disinhibit ipsilateral quadriceps of patients with tibiofemoral osteoarthritis (TFOA), yet no data exists regarding how the contralateral or uninjured quadriceps are affected. PURPOSE: To determine the effects of disinhibitory TENS and therapeutic exercise applied to the injured knee on the uninjured quadriceps central activation ratio (CAR). METHODS: Thirty-six participants with TFOA were stratified by Kellgren-Lawrence Score and baseline CAR, and randomized into 3 groups (control: 5M, 7F; 58.3 ± 11.8yrs, 28.6± 5.6 BMI,), placebo TENS (4M, 8F; 60.3 ± 12.9yrs, 29.5±9.8 BMI) and TENS groups (6 M,6F; 61 ± 10.9yrs, 28.6± 4.8 BMI). The involved leg was determined as the knee that had the most radiographic evidence of TFOA. All groups participated in 12 supervised, unilateral lower extremity exercise sessions over 4 weeks. TENS and placebo TENS groups wore the intervention on the injured leg during all exercise sessions and for at least 8 hours daily for 4 weeks. Quadriceps CAR was tested on the uninvolved quadriceps prior to the intervention and at 2 and 4 weeks following baseline. A 3x3 repeated measures ANOVA was used to detect differences in CAR and standardized effect sizes calculated to assess effect magnitude. RESULTS: No significant differences were found in CAR score between groups at baseline (TENS 86±10, placebo 84±15, control 84±12), 2 weeks (93±4, 84±13, 86±11) or 4 weeks (94±.07, 82±16, 81±17), yet strong to moderate effect sizes were found at 2 weeks (d =.92; 95% confidence interval.05, 1.73) and 4 weeks (.58; -.26, 1.37) in the TENS group. Weak effect sizes were calculated for both the placebo (0; -.8, 8: -.13; -.93,.68) and the control group (.17; -.63,.97: -.2; -1,.61) at 2 and 4 weeks, respectively. CONCLUSION: Although there were no statistically significant differences between groups in the uninvolved leg following 4 weeks of disinhibitory TENS treatment, effect sizes were strong, suggesting a clinically significant increase in uninvolved quadriceps CAR.

Quadriceps Activation Following Knee Injuries: A Systematic Review

Arthrogenic muscle inhibition is an important underlying factor in persistent quadriceps muscle weakness after knee injury or surgery. To determine the magnitude and prevalence of volitional quadriceps activation deficits after knee injury. Web of Science database. Eligible studies involved human participants and measured quadriceps activation using either twitch interpolation or burst superimposition on patients with knee injuries or surgeries such as anterior cruciate ligament deficiency (ACLd), anterior cruciate ligament reconstruction (ACLr), and anterior knee pain (AKP). Means, measures of variability, and prevalence of quadriceps activation (QA) failure (<95%) were recorded for experiments involving ACLd (10), ACLr (5), and AKP (3). A total of 21 data sets from 18 studies were initially identified. Data from 3 studies (1 paper reporting data for both ACLd and ACLr, 1 on AKP, and the postarthroscopy paper) were excluded from the primary analyses because only graphical data were reported. Of the remaining 17 data sets (from 15 studies), weighted mean QA in 352 ACLd patients was 87.3% on the involved side, 89.1% on the uninvolved side, and 91% in control participants. The QA failure prevalence ranged from 0% to 100%. Weighted mean QA in 99 total ACLr patients was 89.2% on the involved side, 84% on the uninvolved side, and 98.5% for the control group, with prevalence ranging from 0% to 71%. Thirty-eight patients with AKP averaged 78.6% on the involved side and 77.7% on the contralateral side. Bilateral QA failure was commonly reported in patients. Quadriceps activation failure is common in patients with ACLd, ACLr, and AKP and is often observed bilaterally.

Quadriceps Weakness, Atrophy, and Activation Failure in Predicted Noncopers after Anterior Cruciate Ligament Injury

Background Quadriceps weakness is common after anterior cruciate ligament injury, especially in those who do not compensate well for the injury (“noncopers”). Both atrophy and activation failure have been demonstrated in this population but have not been directly related to quadriceps weakness. Hypotheses (1) Quadriceps strength, volumes, and cross-sectional areas of the noncopers would be smaller than those of the contralateral muscles, whereas other muscles would not demonstrate atrophy. (2) Quadriceps muscle activation deficits would be observed. (3) Atrophy and activation failure would account for the quadriceps weakness in these patients. Study Design Cross-sectional study, Level of evidence, 3. Methods Seventeen noncopers with isolated anterior cruciate ligament injury underwent burst-superimposition strength and activation testing of the quadriceps and magnetic resonance imaging of 12 muscles an average of 2 months after injury. Morphological characteristics was described by digitally reconstructing each muscle from the axial images and calculating muscle volume and peak cross-sectional area. Results The quadriceps muscles of the anterior cruciate ligament-deficient limb were significantly weaker (average 25%) than those of the uninjured side; activation failure (8%-10%) was observed for the quadriceps muscles of both limbs. The total quadriceps, vastus lateralis, and vastus intermedius volume and cross-sectional area were significantly smaller in the anterior cruciate ligament-deficient limb. There was no significant atrophy of any other muscle or muscle group. Atrophy and activation failure explained more than 60% of the variance in quadriceps weakness (P =. 004). Conclusion The quadriceps femoris weakens soon after acute anterior cruciate ligament injury. Activation deficits and atrophy occur and affect quadriceps strength. Rehabilitation techniques that address activation deficits as well as atrophy may be necessary to restore quadriceps strength.

Quadriceps activation failure as a moderator of the relationship between quadriceps strength and physical function in individuals with knee osteoarthritis.

To determine if quadriceps activation failure (QAF) moderates the relationship between quadriceps strength and physical function in individuals with knee osteoarthritis (OA). Quadriceps strength and QAF were measured in 105 subjects (80 females) with radiographically confirmed knee OA using a burst-superimposition maximum voluntary isometric quadriceps torque test procedure. Subjects performed the Get Up and Go test as a physical performance measure of function and completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) as a self-report measure of function. A principal component analysis was performed to combine the Get Up and Go score and the WOMAC subscores into a single function score. Hierarchical regression analysis was performed to examine the ability of 3 models to predict physical function (strength = function; strength + QAF = function; strength + QAF + [strength x QAF] = function). Partial F tests were used to compare differences in R(2) values between each model. Each model independently predicted the principal component score for function. Adding the strength x QAF interaction term with strength to the model resulted in the highest prediction of function. The strength x QAF interaction indicated that subjects with lower levels of quadriceps strength and higher levels of QAF had lower levels of function than those with comparable levels of weakness but low levels of QAF. The magnitude of QAF serves to moderate the relationship between quadriceps strength and physical function. Physical function may be more severely affected by weakness of the quadriceps muscles in individuals with knee OA who have higher degrees of QAF than those who may have quadriceps weakness, but do not have QAF.

Quadriceps femoris muscle weakness and activation failure in patients with symptomatic knee osteoarthritis

Purpose: Quadriceps weakness is common in patients with knee osteoarthritis (OA), and has been attributed to failure of voluntary activation. Methodological differences may have contributed to previous reports of extensive failure of voluntary activation in patients with osteoarthritis. The purpose of this study was to determine the extent of quadriceps muscle weakness and activation failure in middle aged patients with symptomatic medial knee osteoarthritis using maximum voluntary isometric contractions (MVIC) and a burst superimposition technique. Methods: Measurements of quadriceps MVIC and extent of voluntary activation were made in 12 subjects with knee OA and 12 similarly aged uninjured subjects. Voluntary activation was tested by superimposing a train of electrical stimulation on a maximal effort volitional contraction of the quadriceps muscle. Results: The group of subjects with knee OA had significantly less quadriceps strength relative to body mass index (BMI) than the group of control subjects ( p=0.010). No difference in voluntary activation was observed ( p=0.233), however, 50% of the OA group, and only 25% of the control group failed to fully activate the quadriceps. Discussion: The finding of quadriceps weakness is consistent with past literature. Providing adequate instruction, feedback, and several attempts to maximally contract the muscle likely yielded greater volitional activation (thus less activation failure) than had been reported previously. This finding has implications for the rehabilitation of weakened quadriceps in patients with knee osteoarthritis.

Quadriceps strength and volitional activation before and after total knee arthroplasty for osteoarthritis

Introduction: Patients with osteoarthritis (OA) of the knee have quadriceps weakness and arthrogenous muscle inhibition (AMI). While total knee arthroplasty (TKA) reliably reduces pain and improves function in patients with knee OA, quadriceps weakness persists after surgery. The purpose of this investigation was to assess contributions of AMI to quadriceps weakness before and after TKA and to assess the effect of pain on AMI. Methods: Twenty-eight patients with unilateral, end-stage, primary knee OA were tested an average of 10 days before and 26 days after TKA. The mean age at time of operation was 63 years (range 49–82 years). Measurements on the involved and uninvolved knees were performed using the burst-superimposition technique, where supramaximal electrical stimulation is superimposed on a voluntary contraction. Knee pain during contraction was measured using a numeric rating scale. Results: The involved quadriceps were significantly weaker than the uninvolved prior to TKA ( p<0.05). Quadriceps strength decreased by 60% ( p<0.001) and activation decreased 17% ( p<0.001) after TKA. Changes in muscle activation accounted for 65% of the variability in the change in quadriceps strength ( r 2=0.65) ( p<0.001). Knee pain during muscle contraction accounted for a small, but significant portion of the change in voluntary activation ( r 2=0.22) ( p=0.006). Discussion: Exercise regimens that emphasize strong muscle contraction and clinical tools that facilitate muscle activation like biofeedback and neuromuscular electrical stimulation may be necessary to reverse the quadriceps activation failure and weakness in the patients with knee OA that worsens after TKA. The failure of current rehabilitation regimens to directly address activation deficits within the first months after surgery may explain the persistent quadriceps weakness in patients after TKA.