Experimentally induced emotions, facial muscle activity, and respiratory resistance in asthmatic and non-asthmatic individuals.

We studied the effects of emotion induction on total respiratory resistance, and their relationship with cardiac vagal activity and facial muscle activity in asthma. Groups of 20 asthmatic and 20 non-asthmatic participants were exposed to series of happy and depressing pictures or self-referent Velten statements. Facial electromyographic activity over corrugator supercilii, orbicularis oculi, and zygomaticus major regions was recorded during periods of presentation and imagery of each stimulus. Following each stimulus series, mood, respiratory resistance, ventilation, and cardiac activity including respiratory sinus arrhythmia (RSA) were recorded. Significant increases of respiratory resistance were observed in asthmatic patients following depressing stimulation. Resistance increases were positively correlated with RSA and heart period. No substantial group differences were found in facial response to emotional stimuli. Changes in facial target muscle sites during positive stimulation were inversely correlated with RSA following stimulation. We conclude that respiratory resistance increases in asthmatics following depressing stimulation are dependent on vagal activity. Greater facial muscle activation during emotional stimulation can reduce vagal activation, which is consistent with claims in the clinical literature of the benefits of emotional expression in asthma.