Impact of moderate-severe persistent allergic rhinitis on thoraco-abdominal kinematics and respiratory muscle function.

: To assess thoraco-abdominal kinematics, respiratory muscle strength and electromyographic activity of the diaphragm (EAdi) in moderate-severe allergic rhinitis (AR) patients. : A cross-sectional study involving 40 individuals (20 in the AR group) and 20 in the control group [CG]) was conducted. Ventilatory pattern and chest wall volume distribution (optoelectronic plethysmography), respiratory muscle strength (manovacuometry and sniff nasal inspiratory pressure [SNIP]), and EAdi were assessed in both groups. : The AR patients had impaired thoraco-abdominal kinematics (reduced total chest wall volume) ( = 0.004), lower values of total respiratory cycle time ( = 0.014) and expiratory time ( = 0.006). They also presented an increase of percentage contribution of the abdominal rib cage ( = 0.475) and respiratory rate ( = 0.019). A positive correlation among pulmonary rib cage tidal volume and MIP (r = 0.544;  < 0.001), SNIP (r = 0.615;  < 0.001), and MEP (r = 0.604;  < 0.001) was observed. After adjusting for age, BMI and gender through multivariate analysis, the individuals with AR presented lower values ​​of MIP (β = -24.341; p < 0.001), MEP (β = -0.277;  < 0.001), SNIP (β = -34.687;  < 0.001) and RMS (β = -0.041;  = 0.017). : The individuals with moderate-severe persistent AR had worse respiratory muscle strength, diaphragm activation and chest wall volume distribution with a higher abdominal contribution to tidal volume than the control group. These findings reinforce the notion that the upper and lower airways work in an integrated and synergistic manner.