Effects of Motion Sickness on Encoding and Retrieval Performance and on Psychophysiological Responses

Background: Motion sickness has previously been found to deteriorate performance. In complex working environments, sustained ability to perform despite motion sickness is crucial. This study focuses on effects of motion sickness on encoding and retrieval of words. In addition, the temporal development of psychophysiological responses and their relationship with perceived motion sickness were investigated. Methods: Forty healthy participants (20 male and 20 female, age 19-51) performed an encoding and retrieval task during exposure to an optokinetic drum and were compared with 20 controls (8 male and 12 female, age 21-47) not exposed to motion sickness. Measurements of heart rate, heart rate variability, skin conductance, blood volume pulse, respiration rate, and skin temperature were made throughout optokinetic drum exposure. Results: Moderate levels of motion sickness did not affect the ability to encode or retrieve words. Perceived motion sickness was positively related to heart rate, blood volume pulse and skin temperature and negatively related to respiration rate. Conclusions: The psychophysiological measurements did not show consistent patterns of sympathetic activation and parasympathetic withdrawal, as could be expected. Subjective reports of progressing symptoms are still likely to be the most reliable way of assessing motion sickness

Neck pain intensity does not predict pressure pain hyperalgesia: Re-analysis of seven randomized controlled trials

© 2014 The Authors. Objectives: To determine factors, including pain intensity, associated with pressure pain sensitivity in chronic non-specific neck pain and with changes after therapeutic interventions. Methods: This re-analysis used pooled data from 7 randomized controlled clinical trials. Pressure pain thresholds were assessed at the hand and at the site of maximal pain in the neck region before and after different non-pharmacological interventions. Age, gender, neck pain intensity and duration, mental health, expectancy and time interval between measurements were used to determine factors influencing pressure pain thresholds as well as pressure pain threshold changes. Results: A total of 346 patients (77 males, 269 females, mean age 52.6 years (standard deviation 12.0 years)) were included in study, 306 of whom provided a complete data-set for analysis. Pressure pain thresholds at the neck area or the hand did not correlate with pain intensity. Changes in pressure pain thresholds correlated with time between measurements, indicating time-sensitive changes. Discussion: No coherent correlations between pressure pain thresholds and pain intensity were found. Further research is needed to evaluate the relationship between pain intensity and pressure pain thresholds before its use as a valid substitute of pain rating can be supported. Until then, the results of trials with respect to using pressure pain thresholds as an outcome variable must be interpreted with care

Оценка взаимосвязи иммунного статуса и холестеринового профиля у пациентов с облитерирующим атеросклерозом артерий нижних конечностей

АРТЕРИОСКЛЕРОЗ ОБЛИТЕРИРУЮЩИЙИММУНИТЕТКОНЕЧНОСТЬ НИЖНЯЯХОЛЕСТЕРИ

Foreword

Background: This study compares the levels of algesic substances between subjects with trapezius myalgia (TM) and healthy controls (CON) and explores the multivariate correlation pattern between these substances, pain, and metabolic status together with relative blood flow changes reported in our previous paper (Eur J Appl Physiol 108: 657-669, 2010). Methods: 43 female workers with (TM) and 19 females without (CON) trapezius myalgia were - using microdialysis - compared for differences in interstitial concentrations of interleukin-6 (IL-6), bradykinin (BKN), serotonin (5-HT), lactate dehydrogenas (LDH), substance P, and N-terminal propeptide of procollagen type I (PINP) in the trapezius muscle at rest and during repetitive/stressful work. These data were also used in multivariate analyses together with previously presented data (Eur J Appl Physiol 108: 657-669, 2010): trapezius muscle blood flow, metabolite accumulation, oxygenation, and pain development and sensitivity. Results: Substance P was significantly elevated in TM (p=0.0068). No significant differences were found in the classical algesic substances (p: 0.432-0.926). The multivariate analysis showed that blood flow related variables, interstitial concentrations of metabolic (pyruvate), and algesic (BKN and K+) substances were important for the discrimination of the subjects to one of the two groups (R-2: 0.19-0.31, pless than0.05). Pain intensity was positively associated with levels of 5-HT and K+ and negatively associated with oxygenation indicators and IL-6 in TM (R-2: 0.24, pless than0.05). A negative correlation existed in TM between mechanical pain sensitivity of trapezius and BKN and IL-6 (R-2: 0.26-0.39, pless than0.05). Conclusion: The present study increased understanding alterations in the myalgic muscle. When considering the system-wide aspects, increased concentrations of lactate, pyruvate and K+ and decreased oxygenation characterized TM compared to CON. There are three major possible explanations for this finding: the workers with pain had relatively low severity of myalgia, metabolic alterations preceded detectable alterations in levels of algesics, or peripheral sensitization and other muscle alterations existed in TM. Only SP of the investigated algesic substances was elevated in TM. Several of the algesics were of importance for the levels of pain intensity and mechanical pain sensitivity in TM. These results indicate peripheral contribution to maintenance of central nociceptive and pain mechanisms and may be important to consider when designing treatments.Funding Agencies|Danish Medical Research Council [22-03-0264]; Danish Rheumatism Association [233-1149-02.02.04]; Swedish Research Council [K2011-69X-21874-01-6]; Swedish Council for Working Life and Social Research [2010-0913]</p

Altered neuromuscular control mechanisms of the trapezius muscle in fibromyalgia

<p>Abstract</p> <p>Background</p> <p>fibromyalgia is a relatively common condition with widespread pain and pressure allodynia, but unknown aetiology. For decades, the association between motor control strategies and chronic pain has been a topic for debate. One long held functional neuromuscular control mechanism is differential activation between regions within a single muscle. The aim of this study was to investigate differences in neuromuscular control, i.e. differential activation, between myalgic trapezius in fibromyalgia patients and healthy controls.</p> <p>Methods</p> <p>27 fibromyalgia patients and 30 healthy controls performed 3 minutes bilateral shoulder elevations with different loads (0-4 Kg) with a high-density surface electromyographical (EMG) grid placed above the upper trapezius. Differential activation was quantified by the power spectral median frequency of the difference in EMG amplitude between the cranial and caudal parts of the upper trapezius. The average duration of the differential activation was described by the inverse of the median frequency of the differential activations.</p> <p>Results</p> <p>the median frequency of the differential activations was significantly lower, and the average duration of the differential activations significantly longer in fibromyalgia compared with controls at the two lowest load levels (0-1 Kg) (p < 0.04), but not at the two highest load levels (2 and 4 Kg).</p> <p>Conclusion</p> <p>these findings illustrate a different neuromuscular control between fibromyalgia patients and healthy controls during a low load functional task, either sustaining or resulting from the chronic painful condition. The findings may have clinical relevance for rehabilitation strategies for fibromyalgia.</p

Associations between pain thresholds for heat, cold and pressure, and Pain Sensitivity Questionnaire scores in healthy women and in women with persistent pelvic pain

Background The Pain Sensitivity Questionnaire (PSQ) is a self‐rating instrument developed as a time‐ and cost‐saving alternative to quantitative sensory testing (QST). The aims of the study were to assess (a) the associations between PSQ scores and QST in women with persistent pelvic pain and in pain‐free controls and (b) to what extent demographic variables and psychological distress influenced PSQ scores. Methods Fifty‐five healthy women and 37 women with persistent pelvic pain participated. All filled in the PSQ and Hospital Anxiety and Depression Scale and had QST (heat, cold and pressure pain thresholds) performed on six locations on the body. Information on age, body mass index, smoking habits and pain duration were collected. Principal component analysis and orthogonal partial least square regressions were used. Results The patients scored significantly higher on PSQ than the controls. Significant multivariate correlations between pain thresholds and PSQ scores were found only in the patient group. In the patient group, the heat and cold pain thresholds correlated more strongly with PSQ scores than the pressure pain threshold. Conclusions The PSQ score was significantly higher in pelvic pain patients, and correlations between QSTs and the PSQ were only found for patients. Significance The PSQ reflects pain sensitivity in women with PPP and can be used as a non‐invasive and painless way to assess this condition in clinical practice.Funding Agencies|Medical Research Council of Southeast Sweden; Swedish Research Council; County council of Ostergotland; Linkoping University; IMI Paincare</p

Quantitative EMG Changes During 12-Week DeLorme's Axiom Strength Training

Strength training is one of the most common exercises practiced in the field of physical therapy or sports training. However, limited methodology is available to evaluate its effect on the target muscle. This study aimed to test the hypothesis that surface electromyographic (EMG) data from both isometric and isotonic exercise can express changes within the muscle during a 12-week strength training program. Ten healthy male volunteer students (5 for training, 5 for controls) from Yonsei University were recruited for evaluation in this study. DeLorme's axiom was practiced for 12 weeks in the dominant elbow flexors and knee extensors of the training group. Tension for 1 repetition maximum and maximal voluntary isometric contraction, and surface EMG information such as the integrated EMG and three variables from the regression line of median frequency (MDF) data were measured at weeks 0, 3, 6, 9, and 12. The limb circumference was measured at weeks 0 and 12. During the strength training, which was enough for the increment of muscle strength and limb circumference, the rectified-integrated EMG and initial MDF increased with a significant linear pattern in both types of contraction. The two surface EMG variables were able to monitor the physiologic muscle changes during the training. Based on these results, we propose that these two surface EMG variables can be used for monitoring electrophysiological changes in the specific muscle that is undergoing the training program, under conditions where the contraction mode for EMG data collection is either static or dynamic

Reduced pain thresholds and signs of sensitization in women with persistent pelvic pain and suspected endometriosis

INTRODUCTION: Endometriosis is a gynecological disorder that may cause considerable pelvic pain in women of fertile age. Determining pain mechanisms is necessary in order to optimize the treatment of the disease. The objective of the study was to evaluate pain thresholds in women with persistent pelvic pain with and without confirmed endometriosis, and healthy, unaffected controls, and analyze how pain thresholds in these cohorts related to duration of pelvic pain, quality of life, and symptoms of anxiety and depression. MATERIAL AND METHODS: Pain thresholds for heat, cold and pressure were assessed with quantitative sensory testing on six locations on a reference group of 55 healthy women and on 37 women with persistent pelvic pain who had been admitted for diagnostic laparoscopy on the suspicion of endometriosis. Validated instruments were applied to assess quality of life and symptoms of anxiety and depression. Data were analyzed by means of uni- and multivariate analysis of variance and Spearman's rank-order correlation. RESULTS: The women with persistent pelvic pain had significantly lower pain thresholds compared with the reference women. In the women with pain, no differences were observed in pain thresholds between women with (n = 13) and women without (n = 24) biopsy-proven endometriosis. The duration of pelvic pain correlated significantly positively with reduced pain thresholds, ie, the longer the duration, the more sensitization. In the persistent pelvic pain group, pain thresholds for heat correlated significantly with the Short Form Health Survey 36 dimension of bodily pain, and thresholds for cold correlated with Short Form Health Survey 36 bodily pain and with symptoms of depression. CONCLUSIONS: Our results showed widespread alterations in pain thresholds in women with persistent pelvic pain that are indicative of central sensitization and a time-dependent correlation. Women with pelvic pain and suspicion of endometriosis should probably be treated more thoroughly to prevent or at least minimize the concomitant development of central sensitization.Funding agencies:  Medical Research Council of Southeast Sweden; Region Ostergotland; Linkoping University</p