The effects of inspiratory muscle training on plasma interleukin-6 concentration during cycling exercise and a volitional mimic of the exercise hyperpnea

Abstract

It is unknown whether the respiratory muscles contribute to exercise-induced increases in plasma interleukin-6 (IL-6) concentration, if this is related to diaphragm fatigue, and whether inspiratory muscle training (IMT) attenuates the plasma IL-6 response to whole body exercise and/or a volitional mimic of the exercise hyperpnea. Twelve healthy males were divided equally into an IMT or placebo (PLA) group, and before and after a 6-wk intervention they undertook, on separate days, 1 h of 1) passive rest, 2) cycling exercise at estimated maximal lactate steady state power (EX), and 3) volitional hyperpnea at rest, which mimicked the breathing and respiratory muscle recruitment patterns achieved during EX (HYPEX). Plasma IL-6 concentration remained unchanged during passive rest. The plasma IL-6 response to EX was reduced following IMT (main effect of intervention, P = 0.039) but not PLA (P = 0.272). Plasma IL-6 concentration increased during HYPEX (main effect of time, P < 0.01) and was unchanged postintervention. There was no evidence of diaphragm fatigue (measured by phrenic nerve stimulation) following each trial. In conclusion, plasma IL-6 concentration is increased during EX and HYPEX and this occurred in the absence of diaphragm fatigue. Furthermore, IMT reduced the plasma IL-6 response to EX but not HYPEX. These findings suggest that the respiratory muscles contribute to exercise-induced increases in plasma IL-6 concentration in the absence of diaphragm fatigue and that IMT can reduce the magnitude of the response to exercise but not a volitional mimic of the exercise hyperpnea.

Inspiratory muscle warm-up does not improve cycling time-trial performance

“…Comparable improvements in Yo-Yo test running performance were also observed following an IMW (13-19%) and inspiratory muscle training (16%). It seems inconceivable that any short-term benefits elicited by an IMW would approach / surpass the benefits that result from the morphological adaptations that probably occur in the inspiratory muscles after inspiratory muscle training (Brown et al 2010;Brown et al 2012;Mills et al 2013) and, therefore, it is difficult to resolve why comparable ergogenic benefits were observed. The notion that IMW-mediated increases in MIP elicit reductions in dyspnoea can also be questioned based on reduced dyspnoea persisting >15 min after the IMW was performed (Lin et al 2007;Tong and Fu.…”

“…Pulmonary function and MIP were assessed according to published guidelines Miller et al 2005) using equipment and techniques described previously Mills et al 2013). Briefly, pulmonary function was assessed using a pneumotachograph (Pneumotrac; Vitalograph, Buckinghamshire, UK) calibrated with a 3 L syringe.…”

“…A hand-held mouth pressure meter (MicroRPM; CareFusion, Hampshire, UK) measured MIP, with manoeuvres initiated from residual volume and sustained for at least 1 s. The axles that secure the front forks and the rear incorporate elastic suspension, which permits a more natural side-to-side movement. Ventilatory and pulmonary gas exchange variables were measured using techniques and equipment described previously Mills et al 2013). Briefly, participants wore a facemask (model 7940; Hans Rudolph, Missouri, USA) connected to a flow sensor (ZAN variable orifice pneumotach; Nspire Health, Oberthulba, Germany) that was calibrated using a 3 L syringe.…”

Reproducibility of the bronchoconstrictive response to eucapnic voluntary hyperpnoea

“…28,29 For the 2 weeks prior to each EVH test, participants were free from any chest or upper respiratory tract infection. 19 On EVH test days participants abstained from caffeine and alcohol as they can influence asthma exacerbations, 30,31 and arrived at the laboratory at least 2 h post-prandial.…”

“…Gas concentrations were measured using fast responding laser diode absorption spectroscopy sensors, which were calibrated using gases of known concentration (5% CO 2 , 15% O 2 , balance N 2 ; BOC, Guilford, UK), and ventilatory and pulmonary gas exchange variables were measured breath-by-breath (ZAN 600USB; Nspire Health) as previously described. 28,29 A two-way non-rebreathing valve (2700 Series; Hans Rudolph) was connected distally to the flow sensor and the inspiratory port was connected via a 1.2 m length of corrugated tubing (internal diameter: 35 mm) to a 150 L capacity Douglas bag. Participants inspired from the Douglas bag which was continuously filled with gases of known concentration (21% O 2 , 5% CO 2 , balance N 2 ; BOC).…”