Are voluntary muscle activation deficits in older adults meaningful?

Stevens, Jennifer E.; Stackhouse, Scott K.; Binder‐Macleod, Stuart A.; Snyder‐Mackler, Lynn

doi:10.1002/mus.10279

Cited by 85 publications

(96 citation statements)

References 26 publications

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“…The average voluntary activation for uninvolved side quadriceps was 0.928 (0.103) and ranged from 0.58 to 1.0. These values were lower than our previously published samples of young, active uniiijured subjects (0.978 k 0.005, p < 0.001) [28].…”

Section: Volitional Activationcontrasting

confidence: 77%

“…In our laboratory, incidence of activation failure in young, healthy subjects is approximately 10 per cent [26,28]. Activation failure has been demonstrated in our laboratory using the methods employed in this study in healthy, active, elderly individuals [26]; those with patellar contusion [ 191; those with end-stage knee osteoarthritis and after total knee arthroplasty [27].…”

Section: Introductionmentioning

confidence: 80%

“…We hypothesized that the incidence of quadriceps inhibition would be higher in the anterior cruciate ligament injured limbs than the uninvolved limbs and that the incidence of inhibition in the anterior cruciate ligament deficient limbs would be larger than in our historical sample of healthy young individuals tested in the same manner [28]. We also hypothesized that there would be no difference in inhibition by gender.…”

Section: Introductionmentioning

confidence: 92%

“…Absent the targeting and practice procedures described in our methods, most subjects nalve to the testing demonstrate "failure" of voluntary activation. In 90 per cent of cases in healthy active young subjects, the "failure" resolves during a single testing session [24,25,28]. The fact that a single brief 500 ps, 100 mA pulse activated motor units in a population when a 10-pulse tetanic train of 600 s, 130 V pulses did not suggests that the efforts in the other investigations were submaximal.…”

Section: Relationship Between Voluntary Activation and Quadriceps Indexmentioning

confidence: 99%

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A prospective analysis of incidence and severity of quadriceps inhibition in a consecutive sample of 100 patients with complete acute anterior cruciate ligament rupture

Chmielewski

Stackhouse

Axe

et al. 2004

Journal Orthopaedic Research

Self Cite

127

106

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Background Weakness of the quadriceps femoris muscle after anterior cruciate ligament injury and reconstruction has been attributed to incomplete voluntary activation of the muscle. The literature is conflicting on the incidence of incomplete voluntary quadriceps activation after anterior cruciate ligament injury because of differences in testing methods and population biases. The purpose of this study was to systematically examine the incidence and severity of quadriceps voluntary activation failure in both lower extremities after acute anterior cruciate ligament injury. We hypothesized that the incidence of quadriceps inhibition would be higher in the anterior cruciate ligament injured limbs than the uninvolved limbs, that the incidence of inhibition in the anterior cruciate ligament deficient limbs would be larger than in our historical sample of healthy young individuals tested in the same manner and that there would be no difference in inhibition by gender.Study design: Prospective, descriptive. Methods: One hundred consecutive patients with acute anterior cruciate ligament rupture (39 women and 61 men) were tested when range of motion was restored and effusion resolved, an average of 6 weeks after injury. A burst superimposition technique was used to assess quadriceps muscle activation and strength in all patients. Dependent t-tests were used to compare side-to-side differences in quadriceps strength. Independent t-tests were used to compare incidence of activation failure by gender and make comparisons to historical data on young, active individuals.Results: The average iqvolved side quadriceps activation was 0.92, and ranged from 0.60 to 1.00. The incidence of incomplete activation in the involved side quadriceps was 33 per cent and uninvolved side quadriceps was 31 per cent after acute anterior cruciate ligament rupture. The incidence of incomplete activation bilaterally was 21 per cent. There was no difference in incidence of quadriceps inhibition by gender.Conclusion: The incidence of voluntary quadriceps inhibition on the involved side was three times that of uninjured, active young subjects, but the magnitude was not large. The incidence of quadriceps inhibition on the uninjured side was similar to the injured side.Clinical relevance: Both the incidence and magnitude of quadriceps inhibition after ACL rupture are lower than have previously been reported. The conventional wisdom, therefore, that quadriceps inhibition is a significant problem in this population is challenged by the results of this study. Differences between this study and others include sufficient practice to ensure a maximal effort contraction and rigorous inclusion criteria. The findings have implications for strength testing as well as rehabilitation. The quadriceps index, an assessment of the injured side quadriceps strength deficit may be affected by the presence of voluntary activation failure in the uninvolved side.

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Section: Volitional Activationcontrasting

confidence: 77%

Section: Introductionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 92%

Section: Relationship Between Voluntary Activation and Quadriceps Indexmentioning

confidence: 99%

See 2 more Smart Citations

A prospective analysis of incidence and severity of quadriceps inhibition in a consecutive sample of 100 patients with complete acute anterior cruciate ligament rupture

Chmielewski

Stackhouse

Axe

et al. 2004

Journal Orthopaedic Research

Self Cite

127

106

View full text Add to dashboard Cite

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“…Age-related sensorimotor impairment leads to activation deficit during MVC (Stevens et al, 2003), and this is maximized in PD due to deficits in kinesthesia (Klockgether et al, 1995) (i.e. PD+FOG OFF was hardly capable of recruiting soleus muscle during MVC against an external load).…”

Section: Data Processingmentioning

confidence: 99%

Antagonist muscle co-activation during straight walking and its relation to kinematics: Insight from young, elderly and Parkinson's disease

et al. 2012

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Increased antagonist muscle co-activation of the lower limb during walking seems to be an adaptive process to the physiological changes of aging, in order to gain joint stability. In the healthy subjects this view seems to be reinforced by the fact that the co-activation index (CAI) increases when the gait is faster. The few reports on antagonist coactivation in Parkinson's disease (PD) patients indicate that they have larger co-activation than the healthy elderly, supporting the idea of the stabilization role of CAI during gait, as postural instability is a cardinal feature of PD. However it has also been reported that there is a reduction of the CAI when increasing velocity in PD or normal elderly. This questions the role of coactivation in stabilization during increased velocity. In this study we have analyzed the gait of healthy subjects (young and elderly), and PD patients (with and without freezing of gait, FOG) in order to better understand the relation between co-activation and gait kinematics, and to gain insight into the pathological changes associated with FOG in PD. We used Multiple Linear Regression models to study the relationship in shank muscles between CAI, velocity and cadence. Our results indicate that, for all groups of interest, the relationship between co-activation and the kinematics of gait is poor, due to the high degree of variability, questioning the explanatory value of the index.

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