Biomedical subjects

Pascal Madeleine

Publications and source records attributed to Pascal Madeleine.

27 records · Page 2Linked to original sources

PubMed2004

Sex differences in temporal characteristics of descending inhibitory control: an evaluation using repeated bilateral experimental induction of muscle pain.

Little is known about sex differences in the temporal pattern of descending inhibitory mechanisms, such as descending noxious inhibitory control (DNIC). Sex differences in temporal characteristics of DNIC were investigated by measuring pressure pain thresholds (PPTs) over time in the trapezius muscles (local pain areas) and the posterolateral neck muscles (referred pain areas) following repeated bilateral injection of hypertonic versus isotonic saline into both trapezius muscles. Ten females and 11 males received two consecutive bilateral injections, with 15 min interval, of either 5.8% hypertonic saline (0.5 ml in each side for each bilateral injection) or isotonic saline as a control in a randomized manner. Following hypertonic saline injection, the maximal pain intensities of the first and second bilateral injections were significantly higher in females than in males. The PPTs in the trapezius muscles were significantly lower in females than in males. Significantly higher PPTs (hypoalgesia) in men than in women were shown 15 min after the first bilateral injection, and 7.5 and 15 min after the second bilateral injection in the referred pain areas. Importantly, the second bilateral injection failed to further increase the PPTs for both sexes. These results showed that there were sex differences in temporal characteristics of descending inhibition with long-lasting hypoalgesia in men than in women. Repeated noxious muscular stimuli may inhibit further build-up of DNIC, which may reflect a mechanism of plasticity of the descending inhibitory systems following recurrent nociceptive barrage for both sexes.

Adult↗

PubMed2003

Standardized low-load repetitive work: evidence of different motor control strategies between experienced workers and a reference group.

The purpose of this laboratory study was to evaluate the possible differences in motor strategies to a new standardized low-load repetitive work task in between healthy experienced workers and a reference group. Work task event duration, i.e. working rhythm, cutting forces, surface electromyographic (EMG) activity from four shoulder muscles, postural activity, and arm and trunk movements in 3D were recorded during low-load repetitive work simulation. The experienced group showed lower EMG activity and frequency contents (P<0.05), more abducted position of the upper arm and forward flexion of the trunk prior to work simulation (P<0.05), and increased arm and trunk range of motion (P<0.05) compared with the reference group. The results highlight that experienced butchers have a different motor strategy compared with a reference group, i.e. more variable form of coordination pattern. Furthermore, the initial implementation of a possible protective motor strategy by experienced workers might be a very important prognostic factor.

Adult↗

PubMed2003

Prophylactic tolperisone for post-exercise muscle soreness causes reduced isometric force--a double-blind randomized crossover control study.

The role of tolperisone hydrochloride, a centrally acting muscle relaxant in relieving painful muscle spasm is recently being discussed. The present study hypothesizes that the prophylactic use of tolperisone hydrochloride may effectively relieve post-exercise muscle soreness, based on the spasm theory of exercise pain. Twenty male volunteers, aged 25.2 +/- 0.82 years (mean +/- SEM) participated in 10 sessions in which they received oral treatment with placebo or the centrally acting muscle relaxant tolperisone hydrochloride (150 mg) three times daily for 8 days, in randomized crossover double-blind design. Time course assessments were made for pressure pain threshold, Likert's pain score (0-5), pain areas, range of abduction, isometric force, and electromyography (EMG) root mean square (RMS) during maximum voluntary isometric force on day 1 and 6, immediately after an eccentric exercise of first dorsal interosseous muscle, and 24 and 48 h after the exercise. Treatment with placebo or tolperisone hydrochloride was initiated immediately after the assessments on the first day baseline assessments. On the sixth day baseline investigations were repeated and then the subjects performed six bouts of standardized intense eccentric exercise of first dorsal interosseous muscle for provocation of post-exercise muscle soreness (PEMS). Perceived intensity of warmth, tiredness, soreness and pain during the exercise bouts were recorded on a 10 cm visual analogue pain scale. VAS scores and pressure pain thresholds did not differ between tolperisone and placebo treatment. All VAS scores increased during the exercise bouts 2, 3, 4, 5 and 6 as compared to bout 1. Increased pain scores and pain areas were reported immediately after, 24 and 48 h after exercise. Pressure pain thresholds were reduced at 24 and 48 h after the exercise in the exercised hand. Range of abduction of the index finger was reduced immediately after the exercise and was still reduced at 24 h as compared to the non-exercised hand. The EMG RMS amplitude was also reduced immediately after the exercise, but was increased at 24 and 48 h. Isometric force was reduced immediately after the exercise as compared to days 1, 6, and the 24 and 48 h post-exercise assessments with a greater reduction following the tolperisone hydrochloride treatment and the reduction was more in tolperisone group as compared to the placebo group. The results suggest, that the prophylactic intake of tolperisone hydrochloride provides no relief to pain in course of post-exercise muscle soreness but results in reduction in isometric force.

Adult↗

PubMed2003

Hypoalgesia to pressure pain in referred pain areas triggered by spatial summation of experimental muscle pain from unilateral or bilateral trapezius muscles.

Animal and human experimental studies have suggested the importance of spatial summation in the nociception processing and in the activation of descending inhibition. However, the relationship between the areas (size) of muscles stimulated and the recruitment of descending inhibition has not been addressed. Consequently, we tested whether bilateral versus unilateral injection of hypertonic saline into trapezius muscles caused hypoalgesia to pressure pain (pressure pain thresholds, PPTs) in the local pain areas (the trapezius muscles) and the referred pain areas (the posterolateral neck muscles). Two groups of volunteers participated. One group received a unilateral injection (one injection) and the other group bilateral injections (two injections). In the bilateral group, hypertonic saline was injected in one trapezius first, and 45 s later, while pain was still present from the first injection, a second injection was performed into the contralateral trapezius muscle. The saline-evoked time to maximal pain was significantly shorter after the second injection than after the first injection. More subjects developed referred pain after the bilateral compared with the unilateral injection. In the referred pain areas, the PPTs 7.5 and 15 min after the second injection were significantly increased compared with the first injection, while no changes in the PPT were observed in local and referred pain areas after unilateral injection. This suggests that the induction of descending inhibition was triggered by spatial summation during the later phase of experimentally induced muscle pain. The present experimental model might be used for further investigation of descending inhibition related to the spatial characteristics of nociceptive stimuli in humans.

Adult↗

PubMed2002

The effects of neck-shoulder pain development on sensory-motor interactions among female workers in the poultry and fish industries. A prospective study.

OBJECTIVES: The purpose of this prospective laboratory study was to follow newly employed workers in the fish or poultry industry for 6 months and investigate possible changes in sensory manifestations and motor performance during low load, repetitive work simulation. It was investigated whether the changes were an effect of employment duration and of development of neck-shoulder complaints. METHODS: Twelve newly employed female filleting employees without any sign of neck-shoulder tenderness/pain at the time of employment of 0 months took part in two laboratory recording sessions planned within 1 month of employment and after 6 months of employment at the plant. After 6 months, six workers out of 12 had developed pain and/or tenderness in the neck-shoulder region. The recording sessions evaluated sensory-motor aspects by measuring pressure pain threshold, work-task timing, cutting forces, surface electromyographic activity of four shoulder muscles, displacement of the centre of pressure, and 3D movements of the arm and trunk during simulation of low load, repetitive filleting. RESULTS: Effects due to the duration of employment were observed in both groups, i.e. decreased sensibility to pressure, decrease in the duration of the work cycle, increased arm starting position with respect to the upright position, and decreased range of motion of the arm and trunk (P<0.05) after 6 months. Among the workers with neck-shoulder complaints, increased sensibility to pressure, lower force level, higher electromyographic activity, decreased amplitude of arm movement, and increased trunk posture and movement amplitude (P<0.05) were observed, compared with workers without complaints. CONCLUSIONS: Differences in terms of sensory manifestations and motor control strategy were seen after 6 months of employment with or without neck-shoulder complaints. In general, changes in sensory manifestations and motor control strategy after 6 months work were most likely of importance, as they underlined a learning process as employment duration increased. Moreover, the present sensory-motor changes observed among workers with neck-shoulder complaints highlighted the potential physical risk factors associated with low load, repetitive work.

Adult↗

PubMed2002

Upper trapezius muscle mechanomyographic and electromyographic activity in humans during low force fatiguing and non-fatiguing contractions.

The purposes of this study were firstly to compare and investigate localised fatigue in the upper trapezius muscle in various arm positions as assessed by mechanomyographic (MMG) and surface electromyographic (EMG) signals and secondly to study the effects of different normalisation methods on MMG and EMG signals during non-fatiguing and fatiguing low level isometric contractions. The MMG, EMG and rate of perceived exertion were recorded from 11 subjects in five arm positions (0 degrees abduction and 0 degrees flexion, 45 degrees and 90 degrees flexion, 45 degrees and 90 degrees abduction) with different bilateral arm loads during 3 s for non-fatiguing (0-0.5-1 kg hand-load) and 3 min for fatiguing contractions (1 kg hand-load). The root mean square (RMS), average rectified value (ARV), mean power frequency (MNF), and median power frequency (MDF) of the MMG and EMG signals were computed and normalised with respect to the initial values obtained in the current arm position or in the reference position (0 degrees abduction and 0 degrees flexion) corresponding to the normal postural activity of the trapezius muscle. For fatiguing contractions, differences in magnitude of the increase in the RMS or ARV and decrease in the MNF or MDF were observed for EMG and MMG. The MMG amplitude and spectral changes followed the subjective sensation of fatigue and were not correlated to their EMG counterparts, suggesting that they may reflect different phenomena. For non-fatiguing contractions, normalisation to the current arm position entailed the loss of dynamic amplitude changes suggesting that a single reference contraction in the middle part of the range of movement is enough for proper normalisation of EMG and MMG signals. For fatiguing contractions, normalisation of the EMG and MMG to some extent can lead to a misleading interpretation. Assessment of the upper trapezius muscle by means of MMG may be valuable in ergonomics.

Adult↗

PubMed2002

Development of muscle fatigue as assessed by electromyography and mechanomyography during continuous and intermittent low-force contractions: effects of the feedback mode.

The goal of the present study was to investigate the significance of low-force continuous or intermittent static contraction and feedback mode (visual or proprioceptive) on the development of muscle fatigue as assessed by electromyography (EMG) and mechanomyography (MMG). Visual (force control) and proprioceptive (displacement control) feedback was investigated during intermittent (6 s contraction, 4 s rest) and continuous static contractions at 10% and 30% of the maximum voluntary contraction (MVC). Mean force, force fluctuation, rating of perceived exertion and root mean square (RMS) and mean power frequency (MPF) of the EMG and MMG signals were analysed. The general pattern for MMG RMS and EMG RMS values and the rating of perceived exertion was an increase with contraction time, while the EMG MPF values decreased ( P<0.05). The increase in RMS values was generally more pronounced for the MMG compared with the EMG, while the decrease in MPF values was more consistent for the EMG compared with the MMG signal. During the intermittent contractions, the main effect was on MPF for both EMG and MMG. Lower force fluctuation and larger rating of perceived exertion ( P<0.05), greater slopes of EMG and MMG RMS and MPF values versus time were observed with proprioceptive feedback compared with visual feedback. The findings suggest that (1) the EMG and MMG signals give complementary information about localised muscle fatigue at low-level contraction: they responded differently in terms of changes in the time and frequency domain during continuous contraction, while they responded in concert in the frequency domain during intermittent contractions, and (2) the different centrally mediated motor control strategies used during fatiguing contraction may be dependent upon the feedback modality.

Adult↗

PubMed2002

Standardising surface electromyogram recordings for assessment of activity and fatigue in the human upper trapezius muscle.

The objectives of this work were to determine optimal surface electromyogram (EMG) electrode locations, and inter-electrode distance (IED), when assessing activity and fatigue in the human upper trapezius muscle. Surface EMG signals were recorded from the upper trapezius muscle of 11 healthy male subjects using a linear array of 16 surface electrodes. Five arm positions were investigated (arms at the side of the body, 45 degrees and 90 degrees flexion, 45 degrees and 90 degrees abduction). Fatiguing (1 kg hand load held for 3 min) and non-fatiguing (no load, 0.5 kg and 1 kg hand load held for 3 s) contractions were made. The variabilities of the average rectified value, root mean square, mean and median power spectral frequency and slope over time of these parameters as functions of electrode location and IED (from 5 mm over a range of 35 mm in steps of 5 mm) were quantitatively evaluated. A criterion for selecting the optimal electrode position was applied. This criterion indicated an optimal location measured from the acromion (38% of the distance from the lateral edge of acromion to the spine of the seventh cervical vertebra) which was statistically the same for all the EMG descriptors, arm positions and IED investigated. Finally, it was found that both EMG variables and indexes of muscle fatigue depended on IED which should thus be properly standardised. On the basis of the sensitivity of the EMG descriptors to electrode location and cross-talk reduction, an IED of 20 mm is suggested when a global analysis of activity in the upper trapezius muscle is made using a single pair of electrodes. This study emphasises that a surface EMG analysis of the upper trapezius muscle, following a proper placement of the electrodes and selection of IED, can give reliable indications of muscle activity and fatigue. Data on the myoelectric manifestations of muscle fatigue of the upper trapezius muscle are provided for the optimal electrode location.

Adult↗

PubMed2002

Assessment of postexercise muscle soreness by electromyography and mechanomyography.

Mechanomyography (MMG) and electromyography (EMG) recordings from the first dorsal interosseous muscle of the hand were compared for pre-exercise and immediately after, 24-hour, and 48-hour postexercise muscle soreness. Thirteen healthy male subjects performed progressively increasing number of eccentric contractions from bout 1 (10.34 +/- 1.96) to bout 6 (27.46 +/- 5.01) (P < .03) with 116% maximum voluntary contraction (MVC) for provocation of postexercise muscle soreness. Increased areas of pain, reduced pressure pain threshold, reduced MVC, and reduced range of motion were present immediately after as compared with pre-exercise (P < .05). During intense eccentric exercise, root mean squared amplitude values of MMG increased progressively from bout 1 to bout 6, but EMG root mean squared amplitude decreased as the muscle fatigued (P < .05). Time course changes of MMG and EMG root mean squared amplitude values during single concentric, isometric, and eccentric contractions at 0%, 25%, 50%, 75%, and 100% MVC weights were measured in relation to postexercise muscle soreness. The EMG root mean squared amplitude values showed insignificant changes for concentric, isometric, and eccentric contractions between pre-exercise, immediately after, 24 hours, and 48 hours. MMG root mean squared amplitude values increased during concentric, isometric, and eccentric contractions at immediately after as compared to pre-exercise, 24 hours, and 48 hours. At immediately after, 24 hours, and 48 hours the maximum EMG root mean squared amplitude values were achieved at lower MVC levels as compared with pre-exercise (P < .05). MMG root mean squared amplitude findings suggest changes in viscoelastic properties resulting in significant mechanical muscle vibrations after intense eccentric exercise. This may suggest a role of stimulation of mechanosensitive nociceptors in relation to postexercise muscle soreness. It is concluded that simultaneous recordings of MMG and EMG may serve as an appropriate means of studying the relationship between electrical and mechanical muscle activity occurring with postexercise muscle soreness.

Journal Article↗