Exercise induced hypoalgesia during different intensities of a dynamic resistance exercise: A randomized controlled trial.

INTRODUCTION: Exercise produces an immediate lessening of pain sensitivity (Exercise-Induced Hypoalgesia (EIH)) in healthy individuals at local and distant sites, possibly through a shared mechanism with conditioned pain modulation (CPM). Dynamic resistance exercise is a recommended type of exercise to reduce pain, yet limited research has examined the effects of intensity on EIH during this type of exercise. Therefore, the primary purpose of this study is to compare changes in PPT at a local and distant site during a leg extension exercise at a high intensity, a low intensity, or a quiet rest condition. A secondary purpose is to examine if CPM changes after each intervention. The final purpose is to examine if baseline pain sensitivity measures are correlated with response to each intervention. METHODS: In a randomized controlled trial of 60 healthy participants, participants completed baseline pain sensitivity testing (heat pain threshold, temporal summation, a cold pressor test as measure of CPM) and were randomly assigned to complete a knee extension exercise at: 1) high intensity (75% of a 1 Repetition Maximum (RM), 2) low intensity (30% 1RM), or 3) Quiet Rest. PPT was measured between each set at a local (quadriceps) and distant (trapezius) site during the intervention. CPM was then repeated after the intervention. To test the first purpose of the study, a three-way ANOVA examined for time x site x intervention interaction effects. To examine for changes in CPM by group, a mixed-model ANOVA was performed. Finally, a Pearson Correlation examined the association between baseline pain sensitivity and response to each intervention. RESULTS: Time x site x intervention interaction effects were not significant (F(5.3, 150.97) = 0.87, p = 0.51, partial eta2 = 0.03). CPM did not significantly change after the interventions (time x intervention F(1,38) = 0.81, p = 0.37, partial eta2 = 0.02. EIH effects at the quadriceps displayed a significant, positive moderate association with baseline HPT applied over the trapezius (r = 0.61, p<0.01) and TS (r = 0.46, p = 0.04). DISCUSSION: In healthy participants, PPT and CPM did not significantly differ after a leg extension exercise performed at a high intensity, low intensity, or quiet rest condition. It is possible pre-intervention CPM testing with a noxious stimuli may have impaired inhibitory effects frequently observed during exercise but future research would need to examine this hypothesis.

Professional Exercise Recommendations for Healthy Women Who Are Pregnant: A Systematic Review.

Background: Exercise in pregnancy favorably affects maternal and fetal outcomes, yet only 50% of women receive exercise guidance during prenatal care and 15% are told to stop exercising. Reasons for clinician reluctance to recommend exercise include safety concerns and ambiguity of recommendations. To better inform clinicians, this systematic review assembled a consensus exercise prescription (ExRx) for healthy pregnant women framed by the Frequency, Intensity, Time, and Type (FITT) principle. Methods: In April 2021, PubMed, Scopus, SPORTDiscus, Cumulative Index of Nursing and Allied Health Literature (CINAHL), and Cochrane databases were searched. Reports were eligible if: (1) targeted healthy pregnant women, (2) framed the ExRx by the FITT, and (3) published by a professional society from 2000 to 2021 in English. The Appraisal of Guidelines for Research and Evaluation II tool assessed risk of bias. Results: Twelve reports of poor to good quality were included. Nine societies conducted systematic reviews, but only three provided a detailed, transparent description of the review conducted. Although the FITT varied, the most common was most days of the week, moderate intensity, 30 minutes/session to accumulate 150 minutes/week, and aerobic, resistance, and flexibility exercise with three societies advising neuromotor exercise. All professional societies specified activities to avoid and eight societies included contraindications to exercise. Conclusions: This systematic review produced a consensus ExRx for healthy pregnant women to better inform clinicians about advising their patients to exercise during pregnancy. Future research is needed to determine the upper limits of exercise while pregnant and provide better informed guidance relating to safety concerns for women who are pregnant.