Restitution of EMG spectrum after muscular fatigue

Kuorinka, Ilkka

doi:10.1007/bf00635989

Cited by 61 publications

(38 citation statements)

References 15 publications

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“…From analysis of mean data, they reported the recovery t 1/2 for the mean power frequency to be 1.4 min and for muscle fibre conduction velocity to be 2.1 min. This is somewhat longer than our t 1/2 of about 35 s. Other studies of the parameters of the EMG spectrum have reported that most of the recovery took place during the 1st min (Be´liveau et al 1991;Tho et al 1997;Kuorinka 1988). Kroon and Naeije (1991) made their measurements after 0.75 h; by which time f i had already reached its prefatigued value.…”

Section: Discussionmentioning

confidence: 77%

Recovery of electromyograph median frequency after lumbar muscle fatigue analysed using an exponential time dependence model

Elfving

Liljequist

Dedering

et al. 2002

European Journal of Applied Physiology

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The recovery of the median frequency of the power spectrum of the electromyogram (EMG) after fatigue has been studied to obtain reference data for healthy subjects (n = 55). In a seated position, the subjects performed a 45 s isometric back muscle contraction at 80% of maximal voluntary contraction, followed by 5 s contractions after 1, 2, 3, and 5 min in the recovery phase. In an additional reliability study (n = 11), this was performed six times. Surface EMG was recorded on four sites, namely, bilaterally from the lumbar muscles at the level of the first (L1) and fifth (L5) vertebrae. By non-linear regression, an exponential time dependence model was used to analyse the recovery of median frequency, giving recovery half-time as a resulting measure. Agreement with exponential time dependence was very good (coefficient of determination r(2) = 0.98) in the analysis of mean data (n = 55), with recovery half-times in the range 32-39 s on the four recording sites. Analysis of individual recordings, for which r(2) values in general were lower, revealed further details. Median values of the half-times in general agreed well with the half-times obtained from the analysis of mean data. Recovery half-time and median frequency slope during contraction were not correlated; this is in agreement with what may be expected from an exponential time dependence. Non-significant negative slopes occurred on apparently randomly selected sites, possibly indicating varying muscle coordination in the seated test method. The reliability of the half-time was not sufficient to allow for follow-up measurements on individuals, due to the fluctuations of the recovery data in recordings from individuals.

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Section: Discussionmentioning

confidence: 77%

Recovery of electromyograph median frequency after lumbar muscle fatigue analysed using an exponential time dependence model

Elfving

Liljequist

Dedering

et al. 2002

European Journal of Applied Physiology

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“…The MF decrease of the EMG power spectrum during a fatiguing muscle contraction is mainly attributed to the decrease of the conduction velocity, which reflects the accumulation of metabolic products on the surface area of the muscle fibers (Ducheˆne and Goubel, 1993). However, when complete blood perfusion is allowed, these metabolic products are rapidly washed out so that the muscle membrane function (Miller et al 1987) and the spectral content of EMG signal (Krivickas et al 1996;Kuorinka 1988;Petrofsky 1981) almost completely recovers within the first 5 min of rest.…”

Section: Discussionmentioning

confidence: 97%

Muscle recovery from a short fatigue test and consequence on the reliability of EMG indices of fatigue

et al. 2003

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The purpose of the present study was to evaluate if rest intervals of 10 or 15 min allow the back muscles to recover completely, from an electromyographic (EMG) point of view, after performing a fatiguing contraction. Twelve healthy males stood in a dynamometer with the trunk in a vertical position and performed three trunk extension fatiguing trials (30 s contractions sustained at 75% of the maximal voluntary contraction) separated successively by a 15 min (between trial 1 and 2) and a 10 min (between trial 2 and 3) rest period. The EMG signals from four pairs of back muscles were collected at 2,048 Hz with active surface electrodes. Different EMG indices computed from the temporal and frequency domains of the EMG signal were considered to evaluate muscular fatigue and recovery from trial 1 to trial 2 and from trial 2 to trial 3. No significant differences (one-way ANOVAs between the three trials, alpha=0.05) were obtained for the different EMG indices computed. The percentage of variance explained by the inter-trial effect was none in most cases, corroborating that no systematic error was present between the trials and suggesting that complete muscle recovery was allowed with 10 or 15 min rest periods. These results support the use of rest periods of 10 to 15 min between multiple fatigue tests, at least for back muscles and for high intensity short duration fatigue tasks as the one used in the present study.

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“…Yet most of the recovery process was probably covered. EMG recovery in extremity muscles after an isometric contraction is most rapid within the first minute (Rodriquez et al 1993) and complete after 5 minutes (Kuorinka 1988). Thirdly, the 5 s contractions used to measure fatigue might have been fatiguing themselves, thus affecting the measurement of the recovery process.…”

Section: Discussionmentioning

confidence: 99%

“…When a subject rests after a fatiguing contraction, the median frequency measured from back and extremity muscles recovers to the initial level following an exponential curve function of time (Broman et al 1985;Kuorinka 1988;Vestergaard-Poulsen et al 1995;Alfonsi et al 1999;Elfving et al 2002). An exponential (non-linear) model is superior to models anticipating linearity in the analysis of metabolic changes during muscle contraction and recovery (Simond et al 2001).…”

Section: Introductionmentioning

confidence: 94%

EMG recovery and ratings after back extensor fatigue in patients with lumbar disc herniation and healthy subjects

Dedering

Elfving

Németh

2004

European Journal of Applied Physiology

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This prospective study aimed to examine whether patients with lumbar disc herniation, before and after surgery, showed impaired recovery from fatigue measured with EMG and subjective ratings as compared to healthy subjects. Forty-three patients due for, and after, lumbar disc surgery and 60 healthy subjects were fatigued using a modified Sørensen's test. Recovery of back extensor muscles was assessed using electromyography and the Borg scale ratings at 1, 2, 3, and 5 minutes of recovery, and was further analyzed using an exponential time-dependence model. The patients completed four questionnaires: the Oswestry, the Roland-Morris, a self-efficacy scale and the SF-36. The exponential time-dependence model was successful for 14 of the 43 patients and 57 of the 60 healthy subjects. The patients for whom the model succeeded had significantly better scores on the questionnaires than those for whom the model was unsuccessful. Specific items related to standing and lifting were identified. The patients' recovery was impaired compared to the healthy subjects, as determined by use of the exponential time-dependence model. The combination of fatigue and recovery measures was reflected in the questionnaire scores and is therefore important for evaluating patients with lumbar disc herniation.

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Restitution of EMG spectrum after muscular fatigue

Cited by 61 publications

References 15 publications

Recovery of electromyograph median frequency after lumbar muscle fatigue analysed using an exponential time dependence model

Recovery of electromyograph median frequency after lumbar muscle fatigue analysed using an exponential time dependence model

Muscle recovery from a short fatigue test and consequence on the reliability of EMG indices of fatigue

EMG recovery and ratings after back extensor fatigue in patients with lumbar disc herniation and healthy subjects

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