title: Respiratory muscle tension as symptom generator in individuals with high anxiety sensitivity.
abstract: OBJECTIVE
  Anxiety and panic are associated with the experience of a range of bodily symptoms, in particular unpleasant breathing sensations (dyspnea). Respiratory theories of panic disorder have focused on disturbances in blood gas regulation, but respiratory muscle tension as a source of dyspnea has not been considered. We therefore examined the potential of intercostal muscle tension to elicit dyspnea in individuals with high anxiety sensitivity, a risk factor for developing panic disorder.
  
  
  METHODS
  Individuals high and low in anxiety sensitivity (total N=62) completed four tasks: electromyogram biofeedback for tensing intercostal muscle, electromyogram biofeedback for tensing leg muscles, paced breathing at three different speeds, and a fine motor task. Global dyspnea, individual respiratory sensations, nonrespiratory sensations, and discomfort were assessed after each task, whereas respiratory pattern (respiratory inductance plethysmography) and end-tidal carbon dioxide (capnography) were measured continuously.
  
  
  RESULTS
  In individuals with high compared to low anxiety sensitivity, intercostal muscle tension elicited a particularly strong report of obstruction (M=5.1, SD=3.6 versus M=2.5, SD=3.0), air hunger (M=1.9, SD=2.1 versus M=0.4, SD=0.8), hyperventilation symptoms (M=0.6, SD=0.6 versus M=0.1, SD=0.1), and discomfort (M=5.1, SD=3.2 versus M=2.2, SD=2.1) (all p values<.05). This effect was not explained by site-unspecific muscle tension, voluntary manipulation of respiration, or sustained task-related attention. Nonrespiratory control sensations were not significantly affected by tasks (F<1), and respiratory variables did not reflect any specific responding of high-Anxiety Sensitivity Index participants to intercostal muscle tension.
  
  
  CONCLUSIONS
  Respiratory muscle tension may contribute to the respiratory sensations experienced by panic-prone individuals. Theories and treatments for panic disorder should consider this potential source of symptoms.
authors: Department of Psychology, Southern Methodist University, PO Box 750442, Dallas, TX 75275-0442, USA. tritz@smu.edu
authors: Thomas
authors: T
authors: Ritz
authors: Alicia E
authors: AE
authors: Meuret
authors: Lavanya
authors: L
authors: Bhaskara
authors: Sibylle
authors: S
authors: Petersen
mesh_terms: D000402:Airway Obstruction / Q000503:physiopathology / Q000523:psychology; D000704:Analysis of Variance; D001007:Anxiety / Q000503:physiopathology*; D001288:Attention; D019296:Capnography; D004198:Disease Susceptibility; D004417:Dyspnea / Q000503:physiopathology* / Q000523:psychology; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology / Q000523:psychology; D007366:Intercostal Muscles / Q000503:physiopathology*; D008297:Male; D009129:Muscle Tonus / Q000502:physiology*; D058765:Neurofeedback / Q000379:methods; D016584:Panic Disorder / Q000503:physiopathology* / Q000523:psychology; D010865:Pilot Projects; D010991:Plethysmography; D011597:Psychomotor Performance / Q000502:physiology; D056152:Respiratory Rate / Q000502:physiology; D012307:Risk Factors; D012677:Sensation / Q000502:physiology; D055815:Young Adult