Inspiratory muscle training lowers the oxygen cost of voluntary hyperpnea

Abstract

The purpose of this study was to determine if inspiratory muscle training (IMT) alters the oxygen cost of breathing (Vo(2RM)) during voluntary hyperpnea. Sixteen male cyclists completed 6 wk of IMT using an inspiratory load of 50% (IMT) or 15% placebo (CON) of maximal inspiratory pressure (Pi(max)). Prior to training, a maximal incremental cycle ergometer test was performed to determine Vo(2) and ventilation (V(E)) at multiple workloads. Pre- and post-training, subjects performed three separate 4-min bouts of voluntary eucapnic hyperpnea (mimic), matching V(E) that occurred at 50, 75, and 100% of Vo(2 max). Pi(max) was significantly increased (P < 0.05) by 22.5 ± 8.7% from pre- to post-IMT and remained unchanged in the CON group. The Vo(2RM) required during the mimic trial corresponded to 5.1 ± 2.5, 5.7 ± 1.4, and 11.7% ± 2.5% of the total Vo(2) (Vo(2T)) at ventilatory workloads equivalent to 50, 75, and 100% of Vo(2 max), respectively. Following IMT, the Vo(2RM) requirement significantly decreased (P < 0.05) by 1.5% (4.2 ± 1.4% of Vo(2T)) at 75% Vo(2 max) and 3.4% (8.1 ± 3.5% of Vo(2T)) at 100% Vo(2 max). No significant changes were shown in the CON group. IMT significantly reduced the O(2) cost of voluntary hyperpnea, which suggests that a reduction in the O(2) requirement of the respiratory muscles following a period of IMT may facilitate increased O(2) availability to the active muscles during exercise. These data suggest that IMT may reduce the O(2) cost of ventilation during exercise, providing an insight into mechanism(s) underpinning the reported improvements in whole body endurance performance; however, this awaits further investigation.

Effects of a simple prototype respiratory muscle trainer on respiratory muscle strength, quality of life and dyspnea, and oxidative stress in COPD patients: a preliminary study

“…Moreover, four sessions of thirty repeated inspirations and a 3-minute rest period was designed in this training program within a total duration of 20 minutes of exercise. Although a previous report stated that 30 single breaths with moderate load improved endurance significantly in healthy people,38 some studies presented a non-significant controversial improvement from a low 15% of MIP 39–41. Thus, four repeated sessions of 30 breaths per day for 7 days was possibly enough muscle work to gain respiratory muscle strength.…”

The effects of threshold inspiratory muscle training in patients with chronic obstructive pulmonary disease: A randomised experimental study

“…The score of BDI increased by only one point in the control group, while it sharply increased by more than four points in the experimental group after 2 months. The intervention increased inspiratory muscle strength and endurance, which could lower the oxygen cost of voluntary hyperpnoea, and relieve patients degree of perceived dyspnoea (Turner et al., ). According to a 1‐year longitudinal study by Beckerman et al.…”

“Functional” Respiratory Muscle Training During Endurance Exercise Causes Modest Hypoxemia but Overall is Well Tolerated

“…Most notably, reductions in perceived breathing effort (15) and measured breathing work (1,14,31) delay the development of respiratory muscle fatigue (11)(12)(13), contributing to an attenuation of the respiratory muscle metaboreflex (1,(11)(12)(13)29,33) and improvements on both fixed-workload tasks (29) and time trial performance (1,14). Nearly all RMT studies that have been conducted to date have performed RMT at rest (see (15) for review), which is surprising given that the benefits of RMT (in athletes) are all specific to exercise.…”