Core Function in Adults With Severe Asthma and Its Relationship With Breathing Symptoms.

Background: People with asthma may have skeletal muscle dysfunction but data describing core function in severe asthma are limited.

Objective: To compare core function between people with severe asthma and healthy controls and to determine the difference between males and females. Furthermore, we aimed to investigate the association between core function and breathing symptoms.

Method: Adults with a diagnosis of severe asthma and healthy controls undertook an assessment that included 3 core function tests: partial sit-up, Biering-Sorensen, and side bridge. Breathing symptoms were assessed by the modified Medical Research Council dyspnea scale, modified Borg scale, and Nijmegen questionnaire.

Results: People with severe asthma (n = 136) (38% male, age median [Q1-Q3] 59 y [45-68], body mass index 30 kg/m [26-37]) were compared with 66 people without respiratory disease (47% male, age 55 y [34-65], body mass index 25 kg/m [22-28]). There was no difference between groups in the partial sit-up (P = .09). However, participants with severe asthma performed worse with the Biering-Sorensen (P < .001), and the left and right side bridge test (P < .001 for both) than the healthy comparison group. Similar results were found when comparing males and females separately. Males with severe asthma had increased function compared with their female counterparts in the left side bridge test. Core function tests correlated with the breathing symptom measures, the modified Medical Research Council, modified Borg scale, and Nijmegen questionnaire (-0.51 > r > -0.19; P ≤ .03).

Conclusions: Adults with severe asthma have worse core function than their control counterparts, independent of sex. Furthermore, as core function decreases, breathing symptoms increase.