The importance of normalization in the interpretation of surface electromyography: A proof of principle

Lehman, Gregory J; McGill, Stuart M.

doi:10.1016/s0161-4754(99)70032-1

Cited by 200 publications

(138 citation statements)

References 9 publications

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“…The mean RMS value and SD were calculated and used to normalize activation measures during gait. 37 Time of Activation Relative to Initial Contact. We used a total of 9 ground contacts for data processing of time of activation.…”

Section: Data Processingmentioning

confidence: 99%

Lower Extremity Muscle Activation in Patients With or Without Chronic Ankle Instability During Walking

Feger

Donovan

Hart

et al. 2015

Journal of Athletic Training

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Context: Ankle sprains are among the most common musculoskeletal injuries, and many individuals with ankle sprains develop chronic ankle instability (CAI). Individuals with CAI exhibit proprioceptive and postural-control deficits, as well as altered osteokinematics, during gait. Neuromuscular activity is theorized to play a pivotal role in CAI, but deficits during walking are unclear.Objective: To compare motor-recruitment patterns as demonstrated by surface electromyography amplitudes between participants with CAI and healthy control participants during walking.Design: Descriptive laboratory study. Setting: Laboratory.Patients or Other Participants: Fifteen adults with CAI (5 men, 10 women; age ¼ 23 6 4.2 years, height ¼ 173 6 10.8 cm, mass ¼ 72.4 6 14 kg) and 15 matched healthy control adults (5 men, 10 women; age ¼ 22.9 6 3.4 years, height ¼ 173 6 9.4 cm, mass ¼ 70.8 6 18 kg).Intervention(s): Participants walked shod on a treadmill while surface electromyography signals were recorded from the anterior tibialis, peroneus longus, lateral gastrocnemius, rectus femoris, biceps femoris, and gluteus medius muscles.Main Outcome Measure(s): Preinitial contact amplitude, postinitial contact amplitude, time of activation relative to initial contact, and percentage of activation time across the stride cycle were calculated for each muscle.Results: Time of activation for all muscles tested occurred earlier in the CAI group than in the control group. The peroneus longus was activated for a longer duration across the entire stride cycle in the CAI group (36.0% 6 10.3%) than the control group (23.3% 6 22.2%; P ¼ .05). No differences were noted between groups for measures of electromyographic amplitude at either preinitial or postinitial contact (P . .05).Conclusions: We identified differences between the CAI and control groups in the timing of muscle activation relative to heel strike in multiple lower extremity muscles and in the percentage of activation time across the entire stride cycle in the peroneus longus muscle. Individuals with CAI demonstrated neuromuscular-activation strategies throughout the lower extremity that were different from those of healthy control participants. Targeted therapeutic interventions for CAI may need to be focused on restoring normal neuromuscular function during gait.

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Section: Data Processingmentioning

confidence: 99%

Lower Extremity Muscle Activation in Patients With or Without Chronic Ankle Instability During Walking

Feger

Donovan

Hart

et al. 2015

Journal of Athletic Training

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“…This window of raw EMG activity was processed using the Root Mean Square (RMS) procedure. The mean of the RMS was normalised in relation to a maximal isometric contraction, performed after a warm-up consisting of 3 submaximal isometric contractions (Lehman & McGill, 1999). TA and MG maximal isometric contractions (MIC) were measured with the ankle in neutral position.…”

Section: Data Collectionmentioning

confidence: 99%

Influence of wearing an unstable shoe on thigh and leg muscle activity and venous response in upright standing

et al. 2012

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Purpose: To quantify the effect of unstable shoe wearing on muscle activity and haemodynamic response during standing.Methods: Thirty volunteers were divided into 2 groups: the experimental group wore an unstable shoe for 8 weeks, while the control group used a conventional shoe for the same period. Muscle activity of the medial gastrocnemius, tibialis anterior, rectus femoris and biceps femoris and venous circulation were assessed in quiet standing with the unstable shoe and barefoot.Results: In the first measurement there was an increase in medial gastrocnemius activity in all volunteers while wearing the unstable shoe. On the other hand, after wearing the unstable shoe for eight weeks these differences were not verified. Venous return increased in subjects wearing the unstable shoe before and after training. Conclusions:The unstable shoe produced changes in electromyographic characteristics which were advantageous for venous circulation even after training accommodation by the neuromuscular system.

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“…subcutaneous fat, skin impedance, electrode position etc. [31,40,61]. It has been demonstrated experimentally that the subcutaneous fat layer will affect the intensity of the EMG signals and hence absolute values of EMG should not be taken at face value [20].…”

Section: Emg Findingsmentioning

confidence: 99%

EMG activity of trunk muscles and torque output during isometric axial rotation exertion: a comparison between back pain patients and matched controls

Richardson

Parnianpour

et al. 2002

Journal Orthopaedic Research

137

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Abstract.4bnormal patterns of trunk muscle activity could aKect the biomechanics of spinal movements and result in back pain. The present study aimed to examine electromyographic (EMG) activity of abdominal and back muscles as well as triaxial torque output during isometric axial rotation at different exertion levels in back pain patients and matched controls. Twelve back pain patients and 12 matched controls performed isometric right and left axial rotation at 100%, 70%, 50%) and 30% maximum voluntary contractions in a standing position. Surface EMG activity of rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus were recorded bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were measured. Results showed that there was a trend ( P = 0.08) of higher flexion coupling torque during left axial rotation exertion in back pain patients. Higher activity for external oblique and lower activity for multifidus was shown during left axial rotation exertion in back pain group when compared to the control group. In right axial rotation, back pain patients exhibited lesser activity of rectus abdominis at higher levels of exertion when compared with matched controls. These findings demonstrated that decreased activation of one muscle may be compensated by overactivity in other muscles. The reduced levels of activity of the multifidus muscle during axial rotation exertion in back pain patients may indicate that spinal stability could be compromised. Future studies should consider these alternations in recruitment patterns in terms of spinal stability and internal loading. The findings also indicate the importance of training for coordination besides the strengthening of trunk muscles during rehabilitation process.

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The importance of normalization in the interpretation of surface electromyography: A proof of principle

Cited by 200 publications

References 9 publications

Lower Extremity Muscle Activation in Patients With or Without Chronic Ankle Instability During Walking

Lower Extremity Muscle Activation in Patients With or Without Chronic Ankle Instability During Walking

Influence of wearing an unstable shoe on thigh and leg muscle activity and venous response in upright standing

EMG activity of trunk muscles and torque output during isometric axial rotation exertion: a comparison between back pain patients and matched controls

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