Endogenous opioid effects on motoneuron pool excitability: potential analgesic effect of acute exercise

Spinal Manipulation and Select Manual Therapies: Current Perspectives

Touch is fundamental to the doctor-patient relationship. Touch can produce neuromodulatory effects that mitigate pain and put patients at ease. Touch begins with a confident handshake and continues throughout the physical examination. Touching patients where they hurt is a clear indication that a provider understands their complaint. Touch often continues as a function of treatment. This article updates evidence surrounding human touch and addresses mechanisms of action for manual therapy, the impact of manual therapy on pain management, health care conditions for which manual therapy may be beneficial, treatment plans with dose-response evidence, and the impact of manual therapy on the health care system.

Relationships Between Hoffman Reflex Parameters, Trait Stress, and Athletic Performance

This study evaluated the relationships between trait stress, Hoffman reflex, and performance among 36 healthy amateur male athletes. We first obtained a trait stress questionnaire from participants and then assigned them to high- and low-stress groups. We next recorded Hoffman reflex data from the soleus and lateral gastrocnemius muscles and then examined their athletic performance on testing protocols separated by a 72-hour washout period. Performance testing utilized vertical jump height, 20 -m sprint time, and standing stork tests. There were significant correlations between (a) the standing stork test, vertical jump height, and trait stress and (b) H_max/ M_max ratios, threshold intensity ( H_th), the intensity of the H_max, and the intensity of the H_last. H_th, the intensity of H_max, and the intensity of H_last were significantly higher among the low-stress compared with the high-stress participant groups ( p < .05), despite participants' similar training history. We suggest that self-perceived psychological stress affects performance through neural adaptation.

A meta-analytic review of the hypoalgesic effects of exercise

The purpose of this article was to examine the effects of acute exercise on pain perception in healthy adults and adults with chronic pain using meta-analytic techniques. Specifically, studies using a repeated measures design to examine the effect of acute isometric, aerobic, or dynamic resistance exercise on pain threshold and pain intensity measures were included in this meta-analysis. The results suggest that all 3 types of exercise reduce perception of experimentally induced pain in healthy participants, with effects ranging from small to large depending on pain induction method and exercise protocol. In healthy participants, the mean effect size for aerobic exercise was moderate (d(thr) = .41, d(int) = .59), while the mean effect sizes for isometric exercise (d(thr) = 1.02, d(int) = .72) and dynamic resistance exercise (d(thr) = .83, d(int) = .75) were large. In chronic pain populations, the magnitude and direction of the effect sizes were highly variable for aerobic and isometric exercise and appeared to depend on the chronic pain condition being studied as well as the intensity of the exercise. While trends could be identified, the optimal dose of exercise that is needed to produce hypoalgesia could not be systematically determined with the amount of data available.

PERSPECTIVE

This article presents a quantitative review of the exercise-induced hypoalgesia literature. This review raises several important questions that need to be addressed while also demonstrating that acute exercise has a hypoalgesic effect on experimentally induced pain in healthy adults, and both a hypoalgesic and hyperalgesic effect in adults with chronic pain.

Effects of acute exercise on the soleus H-reflex and self-reported anxiety after caffeine ingestion

The effects of moderate intensity cycling exercise on the soleus H-reflex and state anxiety were examined among 16 individuals whose anxiety was experimentally manipulated by consumption of a large dose of caffeine. The soleus H-reflex and state anxiety were measured before and 1 h after consuming caffeine or placebo and then again 10 min after 30 min of either cycling at an intensity of 60% VO(2peak) or quiet rest. We found that (1) caffeine consumption did not influence the amplitude of the soleus H-reflex, but it did increase state anxiety; (2) acute exercise reduced the soleus H-reflex after consumption of either caffeine or placebo, but it reduced state anxiety only after consumption of caffeine; and (3) there was no evidence of a relationship between changes in the soleus H-reflex and state anxiety. Exercise-induced anxiolysis does not appear to underlie the postexercise reduction of the soleus H-reflex.

Effects of cycling exercise on the soleus H-reflex and state anxiety among men with low or high trait anxiety

The present study examined the effects of low- and high-intensity cycling exercise on the H-reflex and state anxiety among men having low (n=20) or high (n=20) trait anxiety. Participants completed measures of state anxiety and underwent elicitation and recording of the H-reflex in the soleus muscle before and 10 min after three 20-min conditions: (1) quiet rest, (2) cycling at 40% VO2peak, and (3) cycling at 70% VO2peak. We found that (1) exercise, but not quiet rest, resulted in a reduction of the H-reflex; the magnitude of the reduction did not differ between men having low or high trait anxiety; (2) exercise and quiet rest resulted in similar reductions of state anxiety, and the magnitude of the reductions was larger for men having high trait anxiety than low trait anxiety; and (3) reductions of the H-reflex were unrelated to reductions of self-reported state anxiety across all three conditions. Contrary to prior opinion, the postexercise reduction in the H-reflex reported by previous researchers and in the present study appears to be unrelated to self-reported anxiety after exercise.

Acute leg-cycling exercise attenuates the H-reflex recorded in soleus but not flexor carpi radialis

The amplitude of the Hoffman reflex (H-reflex) in the soleus muscle is attenuated after acute bouts of leg-cycling exercise. The attenuation has been interpreted as a "tranquilizing" effect of exercise controlled by the central nervous system and generalized beyond a single spinal segmental level. If so, the postexercise depression of the H-reflex should occur in both the soleus and the flexor carpi radialis (FCR) muscle, which is not actively involved during leg cycling. This experiment examined the effect of moderate-intensity cycling exercise on the H-reflex recorded in soleus and FCR among 16 men. The H-reflex was measured immediately before and 10 min after 30 min of either moderate-intensity leg cycling (60% VO(2peak)) or quiet rest. The acute bout of cycling exercise reduced the H-reflex in the soleus but not in the FCR. Thus, the attenuation of the H-reflex after leg cycling does not generalize beyond the spinal segmental level that modulates the involved locomotory muscles; it is likely the result of segmental processes associated with the repetitive stretching or activation of the soleus muscle.

Endogenous opiates and behavior: 2002

This paper is the twenty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2002 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).