Acute effects of inspiratory pressure threshold loading upon airway resistance in people with asthma

Effect of Inspiratory Muscle Training on Exercise Tolerance in Asthmatic Individuals

“…Emerging evidence suggests that the paradoxical bronchoconstriction occuning in airways of people with asthma after deep inhalation (DI) is nonnalizcd when the DI occurs against a pressure threshold load (14). The modification of airway caliber after DI may be explained by the slow-rate crossbridge cycling in airway smooth muscle, termed the "latched state," which results in increased smooth muscle stiffness (9,12).…”

“…The modification of airway caliber after DI may be explained by the slow-rate crossbridge cycling in airway smooth muscle, termed the "latched state," which results in increased smooth muscle stiffness (9,12). It has been suggested that the chronic application of pressure threshold loading may exert a beneficial influence upon airway smooth muscle by releasing it from its latched state (14). Thus, it is possible that IMT may elicit subtle improvements in airway diameter and airflow litnitation during exercise, thereby reducing dynamic hyperinflation and increasing exercise capacity.…”

Similar Airway Function after Volitional Hyperpnea in Mild-Moderate Asthmatics and Healthy Controls

“…Secondly, maximal decreases in FEV 1 and increases in R5 and X5 were significantly smaller during HYP than responses to mannitol, and maximal declines in FEV 1 during and after HYP were not associated with asthma severity (level of eNO and responsiveness to mannitol) or maximal changes in airway impedance during and after HYP. Thirdly, changes in R5 during HYP 1 were similar in asthmatics and healthy subjects – likely related to the higher flow during assessments [35] resulting from an increased ventilatory drive at HYP termination (rather than bronchoconstriction caused by the preceding period of deep breathing known to increase airway resistance in asthmatics [36]) – in fact, in the combined group (asthmatics and healthy subjects), the higher level of ventilation (HYP 1 bouts 1–5, p < 0.001; HYP 2 , p < 0.005) correlated, although only weakly, with increases in R5 ( r = 0.28, p = 0.002; data not shown). Lastly, the lowest value in FEV 1 was mostly observed immediately after HYP 2 , being back to baseline (±5%) within the first 15 min after the end of HYP in 83% of the asthmatics and 91% of healthy subjects, contrasting the time course of bronchoconstriction induced by exercise where the lowest FEV 1 is observed up to 30 min (or beyond) after exercise [37].…”

Evaluation of the Maximal Respiratory Pressure in Children and Adolescents with Asthma between 7 and 14 Years Old

“…Although controlled, they showed decreased RMS, especially in the group using IC. Perhaps this is due to the fact that bronchial obstruction and lung hyperinflation lead to increased resistance to air flow, which can hamper the respiratory muscles in performing their function in more severe cases [12].…”