Black, CD, Schubert, DJ, Szczyglowski, MK, and Wren, JD. Carbohydrate mouth rinsing does not prevent the decline in maximal strength after fatiguing exercise. J Strength Cond Res 32(9): 2466-2473, 2018-Carbohydrate (CHO) rinsing has been shown to attenuate the decline of maximal voluntary contractions (MVCs) after fatiguing exercise-perhaps through a central mechanism. This study sought to determine the effect of a CHO rinse on MVC, voluntary activation, and contractile properties after fatiguing exercise. Thirteen adults participated in a double-blind, cross-over study. Maximal voluntary contraction of the dominant knee extensors was assessed, and voluntary activation (%VA) was determined using twitch interpolation. Participants then held 50% of MVC until volitional fatigue followed by a 20-second rinse with a solution of 8% maltodextrin (CHO) or placebo (PLA). Maximal voluntary contraction and %VA were reassessed immediately and 5 minutes after exercise. Maximal voluntary contraction did not differ between the CHO and PLA conditions initially (230 ± 90 vs. 232 ± 90 N·m; p = 0.69). Maximal voluntary contraction declined after exercise (p ≤ 0.01), but no differences were found between the CHO and PLA conditions (p ≥ 0.59). %VA did not differ between conditions (91.9 ± 2.9% vs. 91.5 ± 3.8%; p ≥ 0.11) nor did it change after exercise (p = 0.57). Twitch torque, rate of torque development, and rate of torque relaxation were reduced after exercise (p ≤ 0.05) but were unaffected by CHO rinsing (p > 0.05). Unlike a previous study, a CHO rinse did not preserve MVC after fatiguing exercise. This was likely due to a lack of central fatigue induced by the exercise protocol (as %VA was unaffected) as the CHO rinse is thought to work through a central mechanism.
Objective
Athletes are at risk for developing chronic pain conditions, but the role of exercise in the modulation of pain in athletes has not been well established. The aim of this study was to investigate conditioned pain modulation (CPM) and exercise-induced hypoalgesia (EIH) responses between 13 endurance-trained athletes and 13 normally active controls.
Methods
In a cross-sectional, nonrandomized study with two independent groups of college-aged males and females, pressure pain thresholds (PPTs) were assessed in the vastus lateralis (VL) and brachioradialis (BR) using a pressure algometer before and after a conditioning stimulus, an isometric hand grip exercise to failure, and a 30-minute run.
Results
PPTs increased following the conditioning stimulus, indicating a CPM response, to a similar degree in the BR (19.3% ± 26.5% vs 18.6% ± 16.2%, P = 0.93) and VL (18.9% ± 25.9% vs 28.7% ± 27.4%, P = 0.73) in the athletes and controls. PPTs increased following isometric exercise to a similar extent in athletes and controls in the BR (23.9% ± 22.8% vs 28.2% ± 24.0%, P = 0.75) and VL (15.8% ± 14.8% vs 15.5% ± 11.6%, P = 0.94). Following 30 minutes of running, EIH was similar between athletes and controls in the VL (21.2% ± 17.2% vs 13.8% ± 13.3%, P = 0.23) but was attenuated in the BR of the athletes (6.1% ± 16.9% vs 20.9% ± 20%, P = 0.047).
Conclusions
Athletes and controls exhibited similar endogenous pain inhibitory function both locally and systemically following CPM and isometric, upper body exercise. After the 30-minute run, BR EIH was reduced in the athletes compared with controls, suggesting a reduced systemic response following familiar exercise—perhaps due to the exercise being perceived as less painful and/or effortful.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.