Orthostatic-induced Hypotension Attenuates Cold Pressor Pain Perception

In recent years, numerous studies have established a connection between blood pressure and nocioception. While this connection is well documented in the literature, its underlying physiological mechanisms have yet to be elucidated. Much attention has focused on the relationship between cardiovascular regulatory centers and nocioception, yet the intricacies of this relationship have not been fully explored. Therefore, the purpose of this investigation was to examine the role of the baroreflex system as a modulator of pain perception. Twenty normotensive males participated in two laboratory sessions. Time to cold pain threshold and pain tolerance was measured at rest during the first visit. On visit two, blood pressure was orthostatically manipulated via tilt table at postures 90o, 120o, and 180o. Orthostatic manipulation significantly lowered systolic blood pressure (SBP), pain threshold, and pain tolerance from seated baseline at 120o and 180o. The regression models for baroreceptor reflex sensitivity (BRS) assessed during seated baseline and at 120o and 180o revealed a significant negative beta weight for the effect of SBP. A significant negative beta weight for the effects of BRS, SBP, and their interaction was observed at 90o. In conclusion, orthostatic baroreceptor activation appears to exert an inhibitory effect on the brain that decreases pain sensitivity

Exercise Intensity as a Determinant of Exercise Induced Hypoalgesia

The purpose of this study was to examine pain perception during and following two separate 30-min bouts of exercise above and below the Lactate Threshold (LT). Pain Threshold (PT) and Pain Intensity (PI) were monitored during (15 and 30 min) and after exercise (15 and 30 min into recovery) using a Cold Pressor Test (CPT) and Visual Analog Scale (VAS) for pain of the non-dominant hand. Significant differences in PT scores were found both during and after exercise conditions. Post hoc analysis revealed significant differences in PT scores at 30 min of exercise (P=0.024, P=0.02) and 15 min of recovery (P=0.03, P=0.01) for exercise conditions above and below LT, respectively. No differences (P=0.05) in PT scores were found at any time point between exercise conditions. No differences were found in PI scores at any time point within each trial (P=0.05) as well as between exercise conditions (p=0.05). Based upon these data, the effects of moderate exercise on PT appear to be similar at exercise intensities just above and below LT. This may indicate that the requisite intensity needed to ellicit Exercise-Induced Hypoalgesia may be lower than previously reported. Because a hypoalgesic effect was not observed in either condition until 30 min of exercise had been completed, total exercise time may be an important factor in the augmentation of pain perception under these conditions

Current Exercise Behaviors of Breast Cancer Patients Diagnosed with Chemotherapy-Induced Peripheral Neuropathy

Introduction: Chemotherapy-induced peripheral neuropathy (CIPN) is a common, dose-limiting effect of cancer therapy. The neuropathic pain associated with CIPN often has negative implications on an individual’s quality of life (QOL) and has long been recognized as one of the more difficult types of pain to treat. Treatment of neuropathic pain due to CIPN often requires a multidisciplinary approach, with much attention focused on the use of pharmacological therapies. However, in most instances, these agents have been shown to have additional negative side effects for cancer patients. Thus, other interventions that address the symptoms of CIPN should be considered. One such possible intervention is exercise rehabilitation, which has previously been reported effective in attenuating numerous cancer treatment-related toxicities and enhancing the QOL of patients. However, to our knowledge, there have been no published clinical trials examining the role of exercise in preserving neurological function following chemotherapy. As such, the purpose of this investigation was to examine the current exercise habits of breast cancer patients who are diagnosed with CIPN and the impact on pain and QOL. Methods: 300 women listed in the Breast Cancer Registry of Greater Cincinnati database were recruited by mail and asked to complete three questionnaires (McGill QOL, Leeds Assessment of Neuropathic Symptoms and Signs, and Current Exercise Behaviors). Data was analyzed at the 0.05 level of significance using a student’s t-test and a Pearson’s product moment correlation. Results: 134 completed surveys were returned and analyzed (44.6% response rate). Overall, QOL and exercise behaviors were moderately correlated (r = 0.56). Patients reported exercising an average of 2.3 d/wk and an overall QOL of 4.7. Of the patients completing the recommended amount of physical activity (EX, n = 21), QOL was 6.3, which was significantly higher than patients who did not meet these recommendations (SED, n = 113, p\u3c0.001). Likewise, only 15% of EX patients reported experiencing pain compared to 72% of SED patients (p\u3c0.001). Conclusions: Based on these data, it seems likely that an exercise intervention would be successful in attenuating symptoms of CIPN and improving the overall QOL of breast cancer patients

Unmasking Pain: A Look at the Latest Research

Recent research into the physical and psychological mechanisms of pain in revealing new ways to help ease the hurt without the use of medication

The Physiological Consequences of Bed Rest

Bed rest often is used to treat a wide variety of medical conditions. However, bed rest results in profound deconditioning of the body. Bed rest reduces the hydrostatic pressure gradient within the cardiovascular system, reduces muscle force production, virtually eliminates compression on the bones, and lowers total energy expenditure. This review focuses on the deconditioning that occurs in the cardiovascular, muscular, and skeletal systems following bed rest. Reduction in plasma volume reduces cardiac preload, stroke volume, cardiac output, and ultimately, maximal oxygen consumption. Skeletal muscle volume, muscle cross sectional area, and fiber cross sectional area decrease, which results in diminished muscular strength. These changes are most pronounced in the antigravity muscles. Increased bone resorption leads to a negative calcium balance and eventually decreased bone mass, particularly in the lower limbs. Diminished bone mass coupled with decreased muscular strength increases the risk of bone fractures, even with minor falls. It is important for clinicians to recognize these negative consequences of bed rest, which can be explained independent of disease or disorder. With this in mind, bed rest can be minimized as much as possible and early ambulation and physical activity may be prescribed to limit the deconditioning effects of bed rest

Changes in Pain Perception in Women During and Following an Exhaustive Incremental Cycling Exercise

Exercise has been found to alter pain sensitivity with a hypoalgesic response (i.e., diminished sensitivity to pain) typically reported during and/or following high intensity exercise. Most of this research, however, has involved the testing of men. Thus, the purpose of the following investigation was to examine changes in pain perception in women during and following exercise. Seventeen healthy female subjects (age 20.47±.87; VO2 peak 36.77± 4.95) volunteered to undergo pain assessment prior to, during, and after a graded exhaustive VO2 peak cycling challenge. Heart Rate (HR) and Oxygen Uptake (VO2) were monitored along with electro-diagnostic assessments of Pain Threshold (PT) and Pain Tolerance (PTOL) at: 1) baseline (B), 2) during exercise (i.e., 120 Watts), 3) at exhaustive intensity (VO2 peak), and 4) 10 minutes into recovery (R). Data were analyzed using repeated measures ANOVA to determine differences across trials. Significant differences in PT and PTOL were found across trials (PT, p = 0.0043; PTOL p = 0.0001). Post hoc analyses revealed that PT were significantly elevated at VO2 peak in comparison to B (p = 0.007), 120 Watts (p = 0.0178) and R (p = 0.0072). PTOL were found to be significantly elevated at 120 Watts (p = 0.0247), VO2 peak (p \u3c 0.001), and R (p = 0.0001) in comparison to B. In addition, PTOL were found to be significantly elevated at VO2 peak in comparison to 120 Watts (p = 0.0045). It is concluded that exercise-induced hypoalgesia occurs in women during and following exercise, with the hypoalgesic response being most pronounced following exhaustive exercise

An Investigation of Exercise-Induced Hypoalgesia After Isometric and Cardiovascular Exercise

Exercise-induced hypoalgesia is a well-established phenomenon in the literature. The underlying mechanisms responsible for this augmentation of pain perception are not completely understood. The specific mode and intensity of exercise that creates hypoalgesia remains equivocal. Therefore, the purpose of this study was to identify if any differences existed in the exercise-induced hypoalgesia of isometric gripping exercise (IGE) and treadmill exercise (TE). A repeated measures design was used to determine the differences in pain threshold between acute exposure to IGE and TE. Twelve healthy male volunteers served as our subjects. Subjects were tested on three different days under three different conditions (rest, IGE, TE). The order of the trials was randomized and applied force (AF) was used as the dependent variable. Applied force pain threshold (AFPT) was determined by a handheld dolorimeter used to apply progressive force and pain to the skin and muscles of the wrist flexors before and after exercise. Exercise induced hypoalgesia was found in both exercise conditions by comparing resting PPT values (6.23 ± 2.04) to those measured immediately after IGE (7.24 ± 1.61; p = 0.0058) or TE (8.03 ± 2.03; p = 0.0001). However, TE produced a larger (22.04 %) hypoanalgesic effect in comparison to isometric exercise (14.14 %). Both TE and IGE may have potential as methods of increasing one’s pressure pain threshold. Further investigation into the specific causes of exercise-induced hypoalgesia is warranted

An Investigation of the Tri-Bar Gripping System on Isometric Muscular Endurance

Recently, a new product called the Tri-Bar has been introduced as an alternative to the standard weightlifting bar. The Tri-Bar has the same weight, length, and circumference as a standard weightlifting bar and differs only in that the shape of the bar is formed like a triangle with rounded edges. Theoretically, the shape of the bar will enhance gripping comfort and increase muscular endurance. We studied 32 moderately trained males who were free from upper-body injury or limitation. Each participant completed 4 visits to the lab as part of 2 separate investigations. The first investigation was a comparison of straight-arm hang times while grasping a standard Olympic bar or a Tri-Bar revolving handle attached to a weight equal to half the subject\u27s body weight. In both investigations, time was used as a measure of isometric muscular endurance. Differences were determined using a dependent t-test, and a level of significance was set at p is less than 0.05. Mean hang times were significantly longer when the men hung from the Tri-Bar (107.6 seconds) versus the standard bar (95.4 seconds) (p = 0.015). Conversely, in the investigation using the revolving handles, the round bar produced longer grasping times (71.5 seconds) than the Tri_bar (62.6 seconds) (p = 0.000). The results of this investigation indicate that a fixed and stable Tri-Bar may help to increase hang time, but a Tri-Bar free to rotate within the grasp may decrease grasping time in comparison to a standard round handle. With regard to exercises that require isometric grasping, the Tri-Bar may be an effective alternative to the standard bar for increasing isometric grasping endurance

The effect of caffeine ingestion on perception of muscle pain during a sustained submaximal isometric contraction of the quadriceps

Background: The purpose of this study was to determine the effects of an acute dose of 5 mg/kg of caffeine on perceived pain of the quadriceps during a sustained submaximal isometric contraction. Methods: A total of 15 low caffeine consuming college aged women (20.5 ± 1.4 y, 66.0 ± 9.0 kg; mean ± SD) participated in this study. 2–7 d after a familiarization trial subjects ingested, in a double blind random crossover manner, either 5 mg/kg caffeine (Caf) or a placebo (P), 1 h prior to performing a 2 min isometric leg extension at 45% of peak torque using visual cues to maintain force production. Every 15 s subjects rated their level of pain using the Borg CR10 pain scale. Subjects returned to the lab 2–7 d later to repeat the testing with the other condition. Data were analyzed using a repeated measures ANOVA with a Tukey\u27s HSD post hoc. Results: Caffeine ingestion resulted in a lower pain score at all time points during the 2 min isometric contraction. This difference approached significance at 90 s (Caf = 3.2 ± 1.4, P = 4.1 ± 1.4; p \u3c 0.10), and became significantly different at 105 s (Caf = 3.8 ± 1.2, P = 4.9 ± 1.5; p \u3c 0.05) and at 120 s (Caf = 4.4 ± 1.5, P = 5.4 ± 1.5; p \u3c 0.05). Conclusion: Acute caffeine ingestion attenuates perception of muscle pain in the quadriceps during a sustained submaximal isometric contraction. This effect become

The Effects of Isokinetic Contraction Velocity on the Concentric to Eccentric Strength Relationship of the Biceps Brachii

The purpose of this investigation was to determine the influence of contraction velocity on the eccentric (ECC) and concentric (CON) torque production of the biceps brachii. After performing warm-up procedures, each male subject (n = 11) completed 3 sets of 5 maximal bilateral CON and ECC isokinetic contractions of the biceps at three different speeds on a Biodex System 3 dynamometer. The men received a 3-minute rest between sets and the order of exercises was randomized. Peak torque (Nm) values were obtained for CON and ECC contractions at each speed. Peak torque scores (ECC vs. CON) were compared using a t-test at each speed. A repeated measures analysis of variance was used to determine differences between speeds. ECC peak torque scores were greater than CON peak torque scores at each given speed. No differences were found between the ECC peak torque scores (p = 0.62) at any of the speeds. Differences were found among the CON scores (p = 0.004). Post hoc analysis revealed differences. The data suggests that ECC contractions of the biceps brachii were somewhat resistant to a force decrement as the result of an increase in velocity, whereas CON muscular actions of the biceps brachii were unable to maintain force as velocity increased