Measurement and reproducibility of strength and voluntary activation of lower‐limb muscles

Todd, Gabrielle; Gorman, Robert B.; Gandevia, Simon C.

doi:10.1002/mus.20027

Cited by 138 publications

(138 citation statements)

References 35 publications

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“…Twitch interpolation is a commonly used method to estimate the extent to which a person can voluntarily activate a given muscle or muscle group. [27][28][29][30] Our findings of small activation deficits (B5%) in the quadriceps and ankle plantar flexor muscles of noninjured controls are consistent with those from other laboratories. 30 The activation deficits measured in persons with incomplete-SCI (42-66%) are larger in magnitude compared to those measured in patients early after surgery or long-term immobilization.…”

Section: Discussionsupporting

confidence: 91%

Lower extremity skeletal muscle function in persons with incomplete spinal cord injury

et al. 2005

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Study design: A cross-sectional study design. Objectives: To characterize and specifically quantify impairments in muscle function after chronic incomplete spinal cord injury (SCI). Setting: University of Florida, Gainesville, FL, USA. Methods: Voluntary and electrically elicited contractile measurements were performed and voluntary activation deficits were quantitatively determined in the knee extensor and ankle plantar flexor muscle groups in 10 individuals with chronic incomplete SCI (C5-T8, ASIA C or D) and age-, gender-, height-and body weight matched healthy controls. Results: Persons with incomplete-SCI were able to produce only 36 and 24% of the knee extensor torque and 38 and 26% of the plantar flexor torque generated by noninjured controls in the self-reported less-involved and more-involved limbs, respectively (Po0.05). In addition, both indices of explosive or instantaneous muscle strength, torque 200 (absolute torque reached at 200 ms) and the average rate of torque development (ARTD) were dramatically reduced in the ankle plantar flexor and knee extensor muscle groups in persons with incomplete-SCI. However, the deficit in instantaneous muscle strength was most pronounced in the ankle plantar flexor muscles, with an 11.7-fold difference between the torque 200 measured in the self-reported more involved limb and a 5-fold difference in the less-involved limb compared to control muscles. Voluntary activation deficits ranged between 42 and 66% in both muscle groups. Interestingly, electrically elicited contractile properties did not differ between the groups. Conclusion: The resultant impact of incomplete-SCI is that affected muscles not only become weak, but slow to develop voluntary torque. We speculate that the large deficit in torque 200 and ARTD in the ankle plantar flexors muscles of persons with incomplete-SCI may limit locomotor function. The results presented in this study provide a quantitative and sensitive assessment of muscle function upon which future research examining rehabilitation programs aimed at restoring muscle function and promoting functional recovery after incomplete-SCI may be based.

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Section: Discussionsupporting

confidence: 91%

Lower extremity skeletal muscle function in persons with incomplete spinal cord injury

et al. 2005

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“…An excellent level of reliability was evident for measures of neuromuscular function pre-exercise (Table 2), which is in line with the previous work from our laboratory (Goodall et al 2015b;Thomas et al 2015), and importantly, enabled us to detect significant changes throughout the soccer-specific exercise. Similar reliability coefficients have been demonstrated in unfatigued states for both upper (Lee et al 2008;Madsen 1996;Taylor et al 1996) and lower limb (Amann et al 2013;Bachasson et al 2013;Place et al 2007;Todd et al 2004) muscle groups, but the reliability of the fatigue response following locomotor exercise is unknown. The fatigue response was consistent across repeated trials of the SMS, though the variability in the response tended to increase with exercise duration, with most variable responses found at the ET assessment point.…”

Section: Discussionmentioning

confidence: 60%

The assessment of neuromuscular fatigue during 120 min of simulated soccer exercise

et al. 2017

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ET, −18%, P ≤ 0.01), and voluntary activation measured with TMS (−11, −15 and −17%, respectively, P ≤ 0.01) were evident. The fatigue response was robust across both trials; the change in MVC at each time point demonstrated a good level of reliability (CV range 6-11%; ICC 2,1 0.83-0.94), whilst the responses identified with motor nerve stimulation showed a moderate level of reliability (CV range 5-18%; ICC 2,1 0.63-0.89) and the data obtained with motor cortex stimulation showed an excellent level of reliability (CV range 3-6%; ICC 2,1 0.90-0.98). Conclusion Simulated soccer exercise induces a significant level of fatigue, which is consistent on repeat tests, and involves both central and peripheral mechanisms. Keywords

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“…16 The coefficients of variation (CV test-retest ¼ SD/mean) for these measures ranged from 0.9%-6.4%.…”

Section: Reliability Assessmentmentioning

confidence: 99%

“…15,16 Self-adhesive electrodes (7.6 Â 12.7) were placed across the width of the proximal portion of triceps surae muscles just below the knee joint line and across the distal portion of the soleus, superior to the Achilles tendon. A Grass S48 stimulator (Quincy, MA) with a Grass Model SIU8T stimulus isolation unit (Grass Instruments, West Warwick, RI) was used to deliver a supramaximal, monophasic, rectangular pulse with a 600-ms pulse duration to the potentiated muscle at rest, as well as during a maximal voluntary isometric contraction of the plantarflexors.…”

Section: Muscle Activation Testingmentioning

confidence: 99%

Relative contributions of muscle activation and muscle size to plantarflexor torque during rehabilitation after immobilization

Stevens

Pathare

Tillman

et al. 2006

Journal Orthopaedic Research

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Muscle atrophy is clearly related to a loss of muscle torque, but the reduction in muscle size cannot entirely account for the decrease in muscle torque. Reduced neural input to muscle has been proposed to account for much of the remaining torque deficits after disuse or immobilization. The purpose of this investigation was to assess the relative contributions of voluntary muscle activation failure and muscle atrophy to loss of plantarflexor muscle torque after immobilization. Nine subjects (ages 19-23) years with unilateral ankle malleolar fractures were treated by open reduction-internal fixation and 7 weeks of cast immobilization. Subjects participated in 10 weeks of rehabilitation that focused on both strength and endurance of the plantarflexors. Magnetic resonance imaging, isometric plantarflexor muscle torque and activation (interpolated twitch technique) measurements were performed at 0, 5, and 10 weeks of rehabilitation. Following immobilization, voluntary muscle activation (56.8 AE 16.3%), maximal cross-sectional area (CSA) (35.3 AE 7.6cm 2 ), and peak torque (26.2 AE 12.7N-m) were all significantly decreased ( p < 0.0056) compared to the uninvolved limb (98.0 AE 2.3%, 48.0 AE 6.8 cm 2 , and 105.2 AE 27.0 N-m, respectively). During 10 weeks of rehabilitation, muscle activation alone accounted for 56.1% of the variance in torque ( p < 0.01) and muscle CSA alone accounted for 35.5% of the variance in torque ( p < 0.01). Together, CSA and muscle activation accounted for 61.5% of the variance in torque ( p < 0.01). The greatest gains in muscle activation were made during the first 5 weeks of rehabilitation. Both increases in voluntary muscle activation and muscle hypertrophy contributed to the recovery in muscle strength following immobilization, with large gains in activation during the first 5 weeks of rehabilitation. In contrast, muscle CSA showed fairly comparable gains throughout both the early and later phase of rehabilitation. ß

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Measurement and reproducibility of strength and voluntary activation of lower‐limb muscles

Cited by 138 publications

References 35 publications

Lower extremity skeletal muscle function in persons with incomplete spinal cord injury

Lower extremity skeletal muscle function in persons with incomplete spinal cord injury

The assessment of neuromuscular fatigue during 120 min of simulated soccer exercise

Relative contributions of muscle activation and muscle size to plantarflexor torque during rehabilitation after immobilization

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