Aaron J. Stegner

Effect of isometric exercise on pain perception and blood pressure in men and women

PURPOSE To examine the influence of isometric handgrip exercise (ISO EX) on pain perception and blood pressure in men and women. METHODS Fifteen men and 16 women completed max and submax ISO EX consisting of squeezing a hand dynamometer with the right hand as hard as possible for the max session, and squeezing between 40% and 50% of max for 2 min for the submax session. Pain thresholds (PT), pain ratings (PR), blood pressure (SBP and DBP), and heart rate (HR) were assessed while a noxious pressure stimulus was applied to the right forefinger for 2 min before and after ISO EX. Data were analyzed with a 2 (gender) x 2 (trials) ANOVA. RESULTS Results indicated a significant trials effect and a significant gender by trials interaction (P < 0.05) for PT for the max and submax sessions. Women had lower PT before ISO EX in comparison with the men. In addition, PT for the women increased significantly after ISO EX but did not change for the men. There were significant gender and trials effects (P < 0.05) for SBP for the submax session. Women had lower SBP before ISO EX, and SBP increased after ISO EX. DBP was also found to be lower (P < 0.05) in women before max and submax ISO EX, with DBP increasing after submax ISO EX in men and women. PR were found to be lower after max ISO EX in men and women, whereas PR were found to be lower in women after submax ISO EX. CONCLUSION It is concluded that: 1) men and women differed in PT, SBP, and DBP before ISO EX; and 2) analgesia after ISO EX is observed more consistently in women.

Are Women with Fibromyalgia Less Physically Active than Healthy Women

PURPOSE The primary purpose was to quantify and compare physical activity in fibromyalgia (FM) patients to age-matched healthy controls using both objective and self-report measures. Secondary purposes were to compare self-reported and objective measurement of physical activity and to evaluate the relationship between physical activity and pain and mood. METHOD Patients with FM (n=39) and healthy controls (n=40) completed the International Physical Activity Questionnaire and wore an accelerometer at the hip for 7 d. Pain and mood were measured using the McGill Pain Questionnaire, Pain Catastrophizing Scale, Beck Depression Inventory, State-Trait Anxiety Inventory, Profile of Mood States, and Fibromyalgia Impact Questionnaire. RESULTS FM patients had significantly lower physical activity than controls measured by both the International Physical Activity Questionnaire and accelerometer (P<0.05). Both groups self-reported significantly greater moderate and vigorous physical activities than were measured by the accelerometer (P < 0.05). Self-reported and objective measures of time spent in different intensities of activity showed significant correlations in healthy controls (r=0.41-0.51, ρ=0.41, P<0.05). No significant correlations between measures were found in FM patients (P>0.05). Finally, physical activity levels were negatively related (r=-0.37, P<0.05) to depressed mood for FM patients and positively related (r=-0.41, P<0.05) to self-reported vigor for healthy controls. CONCLUSIONS This controlled study objectively demonstrates that FM patients are less physically active than healthy controls, thus extending on two earlier investigations that did not show differences in total physical activity levels using wrist-mounted actigraphy methods. Physical activity levels were not predictive of pain in FM but were significantly related to depressed mood. FM patients may also have a greater variability in their manner of self-report than healthy controls. Therefore, physical activity measurement in FM patients should not be limited solely to self-report measures.

Psychological consequences of exercise deprivation in habitual exercisers

Psychological consequences of exercise deprivation in habitual exercisers. The purpose of this investigation was to evaluate the influence of 3 d of exercise deprivation on selected psychological variables. Ten volunteers (4 female and 6 male) who regularly exercised 6-7 d.wk-1 for at least 45 min at a time participated in a 5-d study. Participants completed their regular workout on the first day of the study, refrained from physical activity for the next 3 d, and then resumed their regular exercise on the 5th d of the study. Participants reported to the lab on Monday following their regular workout and completed a series of questionnaires, and these same questionnaires were completed at the same time of day on the next 4 d. The dependent variables consisted of state and trait anxiety (STAI), and tension, depression, anger, vigor, fatigue, confusion, and overall mood (POMS). Increases in total mood disturbance, state anxiety, tension, depression, and confusion across days were significant (P < 0.05), and vigor decreased. The pattern of increasing mood disturbance with exercise deprivation was followed by mood improvement to baseline levels when exercise was resumed. We concluded that a brief period of exercise deprivation in habitual exercisers results in mood disturbance within 24-48 h.

Physical Activity, Sustained Sedentary Behavior, and Pain Modulation in Women With Fibromyalgia

UNLABELLED Fibromyalgia (FM) has been conceptualized as a disorder of the central nervous system, characterized by augmented sensory processing and an inability to effectively modulate pain. We previously reported that physical activity is related to brain processing of pain, providing evidence for a potential mechanism of pain management. The purpose of this study was to extend our work by manipulating pain modulation and determining relationships to both physical activity and sustained sedentary behavior. Eleven women with FM completed accelerometer measures of physical activity and underwent functional magnetic resonance imaging of painful heat, administered alone and during distracting cognitive tasks. Results showed that physical activity was significantly (P < .005) and positively related to brain responses during distraction from pain in regions implicated in pain modulation including the dorsolateral prefrontal cortex (DLPFC), the dorsal posterior cingulate, and the periaqueductal grey. A significant negative relationship occurred in the left anterior insula. For sedentary time, significant negative relationships were observed in areas involved in both pain modulation and the sensory-discriminative aspects of pain including the DLPFC, thalamus, and superior frontal and pre- and post-central gyri. These results suggest that physical activity and sedentary behaviors are related to central nervous system regulation of pain in FM. PERSPECTIVE Our results support a promising benefit of physical activity and highlight the potentially deleterious effects of sustained sedentary behavior for pain regulation in FM. Studies aimed at increasing physical activity or reducing sedentary behavior and determining the impact of these on pain regulation are warranted.

The relationship between physical activity and brain responses to pain in fibromyalgia.

UNLABELLED The relationship between physical activity and central nervous system mechanisms of pain in fibromyalgia (FM) is unknown. This study determined whether physical activity was predictive of brain responses to experimental pain in FM using functional magnetic resonance imaging (fMRI). Thirty-four participants (n = 16 FM; n = 18 Control) completed self-report and accelerometer measures of physical activity and underwent fMRI of painful heat stimuli. In FM patients, positive relationships (P < .005) between physical activity and brain responses to pain were observed in the dorsolateral prefrontal cortex, posterior cingulate cortex, and the posterior insula, regions implicated in pain regulation. Negative relationships (P < .005) were found for the primary sensory and superior parietal cortices, regions implicated in the sensory aspects of pain. Greater physical activity was significantly (P < .05) associated with decreased pain ratings to repeated heat stimuli for FM patients. A similar nonsignificant trend was observed in controls. In addition, brain responses to pain were significantly (P < .005) different between FM patients categorized as low active and those categorized as high active. In controls, positive relationships (P < .005) were observed in the lateral prefrontal, anterior cingulate, and superior temporal cortices and the posterior insula. Our results suggest an association between measures of physical activity and central nervous system processing of pain. PERSPECTIVE Our data suggest that brain responses to pain represent a dynamic process where perception and modulation co-occur and that physical activity plays a role in balancing these processes. Physically active FM patients appear to maintain their ability to modulate pain while those who are less active do not.

Exercise alters pain sensitivity in Gulf War veterans with chronic musculoskeletal pain.

UNLABELLED Since returning from the Persian Gulf, nearly 100,000 veterans of the first Gulf War (GVs) have reported numerous symptoms with no apparent medical explanation. A primary complaint of these individuals is chronic musculoskeletal pain (CMP). CMP symptoms in GVs are similar to those reported by patients with fibromyalgia (FM), but have not received equivalent scientific attention. Exercise research in CMP patients suggests that acute exercise may exacerbate pain while chronic exercise can reduce pain and improve other symptoms. However, the influence of exercise on GVs with CMP is largely unexplored. This study examined the impact of an acute bout of exercise on pain sensitivity in GVs with CMP. Thirty-two GVs (CMP, n = 15; Control, n = 17) were recruited to complete a series of psychophysical assessments to determine pain sensitivity to heat and pressure stimuli before and after exercise. In response to heat-pain stimuli, GVs with CMP reported higher pain intensity and affect ratings than healthy GVs and exhibited a significant increase in ratings following exercise. GVs with CMP rated exercise as more painful and effortful and were generally more sensitive to heat-pain stimuli than healthy GVs. These results are similar to what has been reported for acute exercise in patients with FM. PERSPECTIVE Gulf War veterans with CMP perceive exercise as more painful and effortful than healthy GVs and experience increased pain sensitivity following exercise. These results suggest that similar abnormalities in central nervous system processing of nociceptive information documented in FM may also be occurring in GVs with CMP.

Exercise Strengthens Central Nervous System Modulation of Pain in Fibromyalgia

To begin to elucidate the mechanisms underlying the benefits of exercise for chronic pain, we assessed the influence of exercise on brain responses to pain in fibromyalgia (FM). Complete data were collected for nine female FM patients and nine pain-free controls (CO) who underwent two functional neuroimaging scans, following exercise (EX) and following quiet rest (QR). Brain responses and pain ratings to noxious heat stimuli were compared within and between groups. For pain ratings, there was a significant (p < 0.05) Condition by Run interaction characterized by moderately lower pain ratings post EX compared to QR (d = 0.39–0.41) for FM but similar to ratings in CO (d = 0.10–0.26), thereby demonstrating that exercise decreased pain sensitivity in FM patients to a level that was analogous to pain-free controls. Brain responses demonstrated a significant within-group difference in FM patients, characterized by less brain activity bilaterally in the anterior insula following QR as compared to EX. There was also a significant Group by Condition interaction with FM patients showing less activity in the left dorsolateral prefrontal cortex following QR as compared to post-EX and CO following both conditions. These results suggest that exercise appeared to stimulate brain regions involved in descending pain inhibition in FM patients, decreasing their sensitivity to pain. Thus, exercise may benefit patients with FM via improving the functional capacity of the pain modulatory system.

Influence of exercise intensity for improving depressed mood in depression: a dose-response study

INTRODUCTION Exercise effectively improves mood in major depressive disorder (MDD), but the optimal exercise stimulus to improve depressed mood is unknown. PURPOSE To determine the dose-response relationship of acute exercise intensity with depressed mood responses to exercise in MDD. We hypothesized that the acute response to exercise would differ between light, moderate, and hard intensity exercise with higher intensities yielding more beneficial responses. METHODS Once weekly, 24 women (age: 38.6±14.0) diagnosed with MDD underwent a 30-minute session at one of three steady-state exercise intensities (light, moderate, hard; rating of perceived exertion 11, 13 or 15) or quiet rest on a stationary bicycle. Depressed mood was evaluated with the Profile of Mood States before, 10 and 30 minutes post-exercise. RESULTS Exercise reduced depressed mood 10 and 30 minutes following exercise, but this effect was not influenced by exercise intensity. Participants not currently taking antidepressants (n=10) had higher baseline depression scores, but did not demonstrate a different antidepressant response to exercise compared to those taking antidepressants. CONCLUSIONS To acutely improve depressed mood, exercise of any intensity significantly improved feelings of depression with no differential effect following light, moderate, or hard exercise. Pharmacological antidepressant usage did not limit the mood-enhancing effect of acute exercise. Acute exercise should be used as a symptom management tool to improve mood in depression, with even light exercise an effective recommendation. These results need to be replicated and extended to other components of exercise prescription (e.g., duration, frequency, mode) to optimize exercise guidelines for improving depression.

Responses to Exercise Differ For Chronic Fatigue Syndrome Patients with Fibromyalgia

UNLABELLED Chronic fatigue syndrome (CFS) and fibromyalgia (FM) are chronic multisymptom illnesses with substantial clinical and diagnostic overlap. We have previously shown that, when controlling for aerobic fitness and accounting for comorbid FM, CFS patients do not exhibit abnormal cardiorespiratory responses during maximal aerobic exercise compared with healthy controls, despite differences in pain and exertion. PURPOSE The purpose of the present study was to examine cardiac and perceptual responses to steady-state submaximal exercise in CFS patients and healthy controls. METHODS Twenty-one CFS patients (13 CFS with comorbid FM (CFS + FM)) and 14 controls completed 20 min of submaximal cycling exercise. Impedance cardiography was used to determine cardiac responses during exercise. Systolic blood pressure (SBP), RPE, and leg muscle pain were also measured. Data were analyzed using a doubly multivariate, repeated-measures MANOVA to model the exercise response. RESULTS There was a significant multivariate time-by-group interaction (P < 0.05). The CFS + FM group exhibited an exercise response characterized by higher stroke index, ventilatory equivalents for oxygen and carbon dioxide and RPE, lower SBP, and similar HR responses compared to controls. CONCLUSIONS The present results extend on our previous work with maximal exercise and show that CFS and CFS + FM differ in their responses to steady-state exercise. These results highlight the importance of accounting for comorbid conditions when conducting CFS research, particularly when examining psychophysiological responses to exercise.

Neural consequences of post-exertion malaise in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Post exertion malaise is one of the most debilitating aspects of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, yet the neurobiological consequences are largely unexplored. The objective of the study was to determine the neural consequences of acute exercise using functional brain imaging. Fifteen female Myalgic Encephalomyelitis/Chronic Fatigue Syndrome patients and 15 healthy female controls completed 30min of submaximal exercise (70% of peak heart rate) on a cycle ergometer. Symptom assessments (e.g. fatigue, pain, mood) and brain imaging data were collected one week prior to and 24h following exercise. Functional brain images were obtained during performance of: 1) a fatiguing cognitive task - the Paced Auditory Serial Addition Task, 2) a non-fatiguing cognitive task - simple number recognition, and 3) a non-fatiguing motor task - finger tapping. Symptom and exercise data were analyzed using independent samples t-tests. Cognitive performance data were analyzed using mixed-model analysis of variance with repeated measures. Brain responses to fatiguing and non-fatiguing tasks were analyzed using linear mixed effects with cluster-wise (101-voxels) alpha of 0.05. Myalgic Encephalomyelitis/Chronic Fatigue Syndrome patients reported large symptom changes compared to controls (effect size ≥0.8, p<0.05). Patients and controls had similar physiological responses to exercise (p>0.05). However, patients exercised at significantly lower Watts and reported greater exertion and leg muscle pain (p<0.05). For cognitive performance, a significant Group by Time interaction (p<0.05), demonstrated pre- to post-exercise improvements for controls and worsening for patients. Brain responses to finger tapping did not differ between groups at either time point. During number recognition, controls exhibited greater brain activity (p<0.05) in the posterior cingulate cortex, but only for the pre-exercise scan. For the Paced Serial Auditory Addition Task, there was a significant Group by Time interaction (p<0.05) with patients exhibiting increased brain activity from pre- to post-exercise compared to controls bilaterally for inferior and superior parietal and cingulate cortices. Changes in brain activity were significantly related to symptoms for patients (p<0.05). Acute exercise exacerbated symptoms, impaired cognitive performance and affected brain function in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome patients. These converging results, linking symptom exacerbation with brain function, provide objective evidence of the detrimental neurophysiological effects of post-exertion malaise.