Controversial literature exists concerning the occurrence of inspiratory muscle fatigue during efforts performed outside a laboratory. The purpose of this study was to assess inspiratory muscle strength and endurance time measured as Tlim, the length of time a subject can endure a task before the onset of fatigue, in ultra-marathon runners by simple non-invasive techniques before and after an ultra-marathon (87 km). Ten runners, (8 males and 2 females), who had normal clinical evaluation and lung function underwent inspiratory muscle assessment by measurement of maximal inspiratory mouth pressures and sustained inspiratory mouth pressures at a given target pressure and a given duty cycle. The measurements were performed prior to the race and 3 days after the race. No significant difference was observed in the inspiratory muscle strength 3 days after the race (p > 0.37), but the inspiratory muscle endurance time as measured by Tlim, was significantly lower (p < 0.002), with an overall decrease of 26.5%. Inspiratory muscle strength was normal 3 days after the race, however the inspiratory muscle endurance time as measured by sustained inspiratory pressure was still impaired 3 days after the race.

In developing countries, rheumatoid arthritis (RA) remains a seriously under-prioritised disease, particularly among the underprivileged, often resulting in presentation of patients late in the course of their disease, further complicated by limited therapeutic options and inconsistent follow up. The consequences are often severe with irreversible disability, increased frequency of co-morbidities, especially cardiovascular disease (CVD), and higher mortality rates, relative to developed countries. Despite addressing traditional cardiovascular risk factors, the impact of subclinical or 'residual' inflammation from uncontrolled RA needs to be considered. This narrative review explores the prevalence and pathogenesis of CVD in RA, including the impact of tobacco use. It discusses pitfalls in the risk assessment of CVD in patients with RA, and the effect of disease-modifying anti-rheumatic therapy on cardiovascular co-morbidity.

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Aim To determine if there is a difference between autonomic cardiac control as measured by heart rate variability (HRV) in females with rheumatoid arthritis (RA) compared to a healthy control group. MethodsThe RA group (45) and control group (39) were matched for age and BMI. Three techniques were used: time domain, frequency domain and Poincarè plot analysis. All possible confounding factors were excluded and the test environment strictly regulated.

The objective of this study is to evaluate the effect of exercise on cardiac autonomic function as measured by short-term heart rate variability (HRV) in females suffering from rheumatoid arthritis (RA). Females with confirmed RA were randomly assigned to an exercise group (RAE) and a sedentary group (RAC). RAE was required to train under supervision two to three times per week, for 3 months. Three techniques (time domain, frequency domain and Poincaré plot analyses) were used to measure HRV at baseline and study completion. At baseline, RAC (n018) had a significantly higher variability compared to RAE (n019) for most HRV indicators. At study completion, the variables showing significant changes (p00.01 to 0.05) favoured RAE in all instances. Wilcoxon signed rank tests were performed to assess changes within groups from start to end. RAE showed significant improvement for most of the standing variables, including measurements of combined autonomic influence, e.g. SDRR (p00.002) and variables indicating only vagal influence, e.g. pNN50 (p00.014). RAC mostly deteriorated with emphasis on variables measuring vagal influence (RMSSD, pNN50, SD1 and HF (ms 2 )). Study results indicated that 12 weeks of exercise intervention had a positive effect on cardiac autonomic function as measured by short-term HRV, in females with RA. Several of the standing variables indicated improved vagal influence on the heart rate. Exercise can thus potentially be used as an instrument to improve cardiac health in a patient group known for increased cardiac morbidity.