%0 Journal Article %A Dean Mills %A Graham Sharpe %A Michael Johnson %A Yvonne Barnett %T The effects of inspiratory muscle training on breathing mechanics during fixed load cycling exercise %D 2011 %J European Respiratory Journal %P p2104 %V 38 %N Suppl 55 %X Previous research has found that inspiratory muscle training (IMT) can improve exercise performance and tolerance (McConnell and Romer 2004). Whether these improvements are related to changes in breathing mechanics during exercise is unknown. To investigate this, we tested the hypothesis that IMT would reduce inspiratory muscle strength during cycling exercise. Three physically active males cycled for 60 min at a fixed power output before and after 6 weeks of pressure-threshold IMT. Cycling power corresponded to maximum lactate steady state, estimated using a lactate minimum test (Tegtbur et al. 1993). Transdiaphragmatic pressure (Pdi) was calculated as the difference between gastric and oesophageal pressures (Pe) measured using balloon pressure catheters. Transdiaphragmatic (PTPdi) and oesophageal (PTPe) pressure-time products were calculated as the product of breathing frequency (fR) and the Pdi and Pe inspiratory time integrals respectively. Pdi, Pe and respiratory variables were measured on a breath-by-breath basis. Following IMT, peak Pdi decreased by (mean ± SD) 6.65±4.82 cmH2O and PTPdi and PTPe by 115±31 and 102±28 cmH2O s min-1, respectively. There was no change in the contribution of the diaphragm to total inspiratory force output (PTPdi/PTPe). Minute ventilation and fR were also reduced by 8.73±10.20 l min-1 and 4.06±2.70 breaths min-1, respectively. In conclusion, inspiratory muscle strength is reduced during a 60 min fixed load cycling test following IMT. These findings suggest that one of the potential mechanisms by which IMT increases exercise tolerance may be by reducing the pressures required to sustain ventilation during fixed load cycling exercise. %U