Persistent Contralateral Pain Compromises Exercise Tolerance but Does not Alter Corticomotor Responses During Repeated, Submaximal Isometric Knee Extensions to Task Failure.

Muscle pain is an important determinant of exercise tolerance, but its relationship with neurophysiological responses during a submaximal exercise trial is unclear. The purpose of this study was to determine the effect of persistent contralateral pain on neurophysiological function and perceptual responses during ipsilateral isometric knee extensions to task failure. Ten participants performed a single-leg repeated submaximal isometric knee extensions with (PAIN) or without (CTRL) constant pain induced by intermittent blood flow occlusion combined with evoked muscle contraction applied to the contralateral, resting leg. Transcranial magnetic stimulation (TMS) applied over the motor cortex was used to assess corticospinal excitability (quantified as motor evoked potentials), corticospinal inhibition (quantified as silent period duration), and short interval intracortical inhibition. Maximal voluntary contractions (MVCs), coupled with femoral nerve stimulation to the exercising leg, were performed every 12 submaximal contractions to assess neuromuscular function. Perceived leg pain and effort were also assessed throughout the exercise. The experimental pain shortened the time to task failure compared to CTRL (P = 0.019). Although time effects were present, no differences appeared between conditions for MVC force, voluntary activation, or potentiated twitch force across both tasks (all P > 0.05). Additionally, no differences between CTRL and PAIN were demonstrated for any TMS-derived measures assessing corticospinal responses. Exercising leg pain was higher in CTRL (P = 0.018), as was perceived exertion (P = 0.030). Overall, when using a persistent, submaximal experimental pain intervention, it appears that although muscle pain compromises exercise tolerance, this phenomenon occurs independently of potential alterations in corticomotor mechanisms.

Changing trends in the profile of rodenticide poisoning.

Background: Deliberate self-poisoning (DSP) is one of the leading causes of mortality and morbidity, with rodenticides being common compounds used by many victims. However, comprehensive data regarding the spectrum and outcome of rodenticide poisoning is scant. Method: This retrospective study was conducted in the Emergency Department (ED) of a large tertiary care hospital in South India between January 2017 and December 2018. All patients with deliberate consumption of rodenticides were included in the analysis. Results: During the study period, 1802 patients presented with DSP, among which 145 (8%) consumed rodenticide compounds. The mean (SD) age was 27.9 (10.7) years. Young adults (16-30 years) comprised 73% (106/145) of the study population. The majority (87%) were triaged as priority 2, while 10% were triaged as priority 1. Common rodenticide compounds consumed were yellow phosphorous (57%: 82/145), coumarins (12%: 17/145), zinc phosphide (19%: 27/145), and aluminum phosphide (1%: 1/145). A significant proportion of patients (18.6%) were under the influence of alcohol. Among the 73 males, 25 (34.2%) gave a history of co-consumption of alcohol. There was a history of previous DSP attempts in 6%. The majority (68%) of the patients were discharged alive from the hospital, and the in-hospital mortality rate was 9%. Age >30 years (adjusted OR: 2.2; 95% CI: 1.00-5.05; p value: 0.04) was an independent predictor of poor outcome. Conclusion: Rodenticide compound consumption for DSP is prevalent in young adults and is associated with significant mortality, especially with yellow phosphorous poisoning. The current trend in our country of the increasing use of highly fatal phosphorous compounds over the innocuous coumarin derivatives is a cause of grave concern.