Exercise and pain: the neurobiology, measurement, and laboratory study of pain in relation to exercise in humans.
Department of Excercise Science, University of Georgia, Athens, USA.Exercise and Sport Sciences Reviews (Impact Factor: 5.28). 02/1999; 27:119-66. DOI: 10.1249/00003677-199900270-00007
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ABSTRACT: The purposes of this study were to assess corticomotor excitability in people with fibromyalgia during a noxious stimulus before and after fatiguing exercise and examine associations with pain perception. Fifteen women with fibromyalgia completed three sessions: one familiarization and two experimental. The experimental sessions were randomized and involved measurement of pain perception and motor evoked potentials before and after (1) quiet rest and (2) isometric contraction of the elbow flexor muscles. Motor evoked potential amplitude of brachioradialis muscle was measured following transcranial magnetic stimulation delivered before, during, and after a noxious mechanical stimulus. After quiet rest, there was no change in pain perception. After the submaximal contraction, there was considerable variability in the pain response. Based on the changes in the experimental pain, subjects were divided into three groups (increase, decrease, and no change in pain). There was an interaction between pain response and the pain-induced change in motor evoked potentials. Those individuals who had an increase in motor evoked potentials during the pain test had an increase in pain after exercise. Thus, women with fibromyalgia were classified based on their pain response to exercise, and this response was associated with the change in corticomotor excitability during the application of a noxious stimulus.Journal of clinical neurophysiology: official publication of the American Electroencephalographic Society 02/2014; 31(1):94-8. · 1.47 Impact Factor
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ABSTRACT: This study investigated change in the distribution of lumbar erector spinae muscle activity and pressure pain sensitivity across the low back in individuals with low back pain (LBP) and healthy controls. Surface electromyographic (EMG) signals were recorded from multiple locations over the lumbar erector spinae muscle with a 13×5 grid of electrodes from 19 people with chronic non-specific LBP and 17 control subjects as they performed a repetitive lifting task. The EMG root mean square (RMS) was computed for each location of the grid to form a map of the EMG amplitude distribution. Pressure pain thresholds (PPT) were recorded before and after the lifting task over a similar area of the back. For the control subjects, the EMG RMS progressively increased more in the caudal region of the lumbar erector spinae during the repetitive task resulting in a shift in the distribution of muscle activity. In contrast, the distribution of muscle activity remained unaltered in the LBP group despite an overall increase in EMG amplitude. PPT was lower in the LBP group after completion of the repetitive task compared to baseline (average across all locations: pre: 268.0±165.9kPa; post: 242.0±166.7kPa) whereas no change in PPT over time was observed for the control group (320.1±162.1kPa; post: 322.0±179.5kPa). The results demonstrate that LBP alters the normal adaptation of lumbar erector spinae muscle activity to exercise which occurs in the presence of exercise-induced hyperalgesia. Reduced variability of muscle activity may have important implications for the provocation and recurrence of LBP due to repetitive tasks.Pain 02/2014; · 5.64 Impact Factor
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ABSTRACT: A clinical study was undertaken to evaluate the associations between the tissue levels of omega-3 (N3), also known as the Omega-3 Index (N3 Index), on various clinical and quality of life outcomes in healthy young adults after heavy eccentric exercise.. To ensure an adequate number of participants with an elevated N3 index would be available for comparison to those with a lower N3 Index, a subgroup of the study participants received N3 dietary supplementation (2.7 g·d(-1)) for 30 days prior to the performance of the heavy eccentric exercise. The remaining participants received a placebo supplement for the same 30-day period. After 30 days of supplementation, participants performed an eccentric exercise routine and were then measured at baseline (time 0), 24-, 48-, 72-, and 96 hours respectively on the following outcomes; C-reactive protein (CRP) and creatine kinase. Blood lactate levels were analyzed immediately after the exercise. Functional measurements of delayed onset of muscle soreness (DOMS), extension and torque were also analyzed. Quality of life (QOL) was measured by the quantitative questionnaire, the Profile of Mood States Questionnaire (POMS). Safety monitoring and analysis of adverse events was continuous throughout the study. Differences as demonstrated by a reduction in pain following eccentric exercise was experienced at both 72 and 96 hour time points in subjects with a higher N3 Index however there were no differences in extension or strength between the two groups. There was a significant difference in blood lactate levels (p = 0.0309) and improved emotional stability, reflected by the POMS questionnaire, in subjects with a higher N3 Index level. There was a statistically significant difference in CRP levels in subjects with a higher N3 Index level at 24 hours and a trend toward significance over 96 hours. There were no significant differences in creatine kinase levels and no reported adverse events. Subjects with a higher Omega-3 (N3) Index reported less pain related to DOMS following heavy exercise at 72 and 96 hours post-exercise. Reduced pain in the higher N3 Index Group may be due to an increased concentration of omega-3 fatty acids in the muscle cell walls, thus triggering a higher elasticity, flexibility and lower risk of physical damage to muscle tissue during exercise. Serum levels of blood lactate were lower in subjects with a high N3 Index, CRP was reduced at 24 hours and POMS scores were improved in high N3 Index subjects demonstrating better QOL. No serious adverse events were reported further supporting that omega-3 dietary supplementation is safe, bio-available and may improve athletic performance and well being in healthy young adults. Key PointsOmega-3 index (N3) is elevated after supplementation versus placebo in healthy young adultsSubjects with higher N3 index demonstrated reduced DOMS after heavy exerciseSubjects with higher N3 index reported better quality of life.Journal of sports science & medicine 01/2014; 13(1):151-6. · 0.89 Impact Factor
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