Exercise-induced respiratory muscle fatigue: implications for performance

It is commonly held that the respiratory system has ample capacity relative to the demand for maximal O-2 and CO2 transport in healthy humans exercising near sea level. However, this situation may not apply during heavy-intensity, sustained exercise where exercise may encroach on the capacity of the respiratory system. Nerve stimulation techniques have provided objective evidence that the diaphragm and abdominal muscles are susceptible to fatigue with heavy, sustained exercise. The fatigue appears to be due to elevated levels of respiratory muscle work combined with an increased competition for blood flow with limb locomotor muscles. When respiratory muscles are prefatigued using voluntary respiratory maneuvers, time to exhaustion during subsequent exercise is decreased. Partially unloading the respiratory muscles during heavy exercise using low-density gas mixtures or mechanical ventilation can prevent exercise-induced diaphragm fatigue and increase exercise time to exhaustion. Collectively, these findings suggest that respiratory muscle fatigue may be involved in limiting exercise tolerance or that other factors, including alterations in the sensation of dyspnea or mechanical load, may be important. The major consequence of respiratory muscle fatigue is an increased sympathetic vasoconstrictor outflow to working skeletal muscle through a respiratory muscle metaboreflex, thereby reducing limb blood flow and increasing the severity of exercise-induced locomotor muscle fatigue. An increase in limb locomotor muscle fatigue may play a pivotal role in determining exercise tolerance through a direct effect on muscle force output and a feedback effect on effort perception, causing reduced motor output to the working limb muscles

Juried Art Exhibition: #1

A part of the undergraduate research component of the University of Louisiana System Academic Summit, this exhibition offered students the opportunity to present their work in a gallery setting and experience art installation, the jurying process, and the promotion of a professional show. A select group of 32 entries were chosen from over 400 submissions

Juried Art Exhibition: #1

A part of the undergraduate research component of the University of Louisiana System Academic Summit, this exhibition offered students the opportunity to present their work in a gallery setting and experience art installation, the jurying process, and the promotion of a professional show. A select group of 32 entries were chosen from over 400 submissions

Social isolation, loneliness and physical performance in older-adults: fixed effects analyses of a cohort study

Isolation and loneliness are related to various aspects of health. Physical performance is a central component of health. However, its relationship with isolation and loneliness is not well understood. We therefore assessed the relationship between loneliness, different aspects of social isolation, and physical performance over time. 8,780 participants from the English Longitudinal Study of Ageing, assessed three times over 8 years of follow-up, were included. Measures included physical performance (Short Physical Performance Battery), loneliness (modified UCLA Loneliness Scale), and isolation considered in three ways (domestic isolation, social disengagement, low social contact). Fixed effects regression models were used to estimate the relationship between changes in these parameters. Missing data were imputed to account for variable response and ensure a representative sample. Loneliness, domestic isolation and social disengagement were longitudinally associated with poorer physical performance when accounting for both time-invariant and time-variant confounders (loneliness: coef = - 0.06, 95% CI - 0.09 to - 0.02; domestic isolation: coef = - 0.32, 95% CI - 0.46 to - 0.19; social disengagement: coef = - 0.10, 95% CI - 0.12 to - 0.07). Low social contact was not associated with physical performance. These findings suggest social participation and subjectively meaningful interpersonal interactions are related to physical performance, and highlight additional considerations regarding social distancing related to COVID-19 control measures

Exercise response to oxygen supplementation is not associated with survival in hypoxemic patients with obstructive lung disease

Purpose: Hypoxemia is associated with more severe lung disease and worse outcomes. In some patients with chronic obstructive lung diseases who desaturate on exertion, supplemental oxygen improves exercise capacity. The clinical significance of this exercise response to oxygen supplementation is not known. Patient and methods: We identified chronic obstructive lung disease patients at our center who underwent a six-minute walking test (6MWT) for ambulatory oxygen assessment and who desaturated breathing air and therefore had an additional walk test on supplemental oxygen, between August 2006 and June 2016. Responders were defined as walking >26m further with oxygen. Survival was determined up to 1st February 2017. We compared survival in oxygen responders and non-responders in patients with obstructive lung diseases. Results: 174 patients were included in the study, median age 70 years. 77(44.3%) of the patients were oxygen responders. Borg dyspnea score improved by 1.4(±1.4) units (P<0.0005) on oxygen. Median survival was 66 months with death occurring in 84(48.2%) patients. Kaplan-Meier analysis revealed no survival difference between both responders and non-responders (P=0.571). Cox regression analysis showed that more 6MWT desaturation, lower 6MWD on room air, male gender, lower hemoglobin and BMI were associated with higher mortality risk. Conclusion: Acute exercise response to supplemental oxygen is not associated with long-term survival in patients with obstructive lung disease. This supports the use of ambulatory oxygen treatment for symptomatic purposes only

A Case of Motor Neuron Disease Presenting as Dyspnea in the Emergency Department

Motor neuron disease encompasses a group of progressive neurologic disorders that destroy cells responsible for the control of essential muscles. The disorders are characterized by progressive weakness, muscle atrophy and fasciculation, spasticity, dysarthria, dysphagia, and respiratory compromise. A 66-year-old male presented to the emergency department with progressive dyspnea and, ultimately, respiratory failure. In spite of extensive cardiopulmonary evaluation, a cause could not be identified except aging. After complete history taking, physical and neurologic examination, motor neuron disease was suspected at last. Thus, elderly patients with dyspnea in the emergency department could have hidden diseases beyond the normal aging process