Multi-site intercostal vibration enhances ventilation through rib cage expansion in healthy adults

Background Vibration applied to the chest wall can activate the tonic vibration reflex (TVR), potentially increasing respiratory muscle activity and ventilation. While single-site intercostal stimulation has shown such effects, it is unclear whether multi-site stimulation provides greater benefits. Objective To investigate whether synchronised multi-site intercostal vibration enhances ventilation through increased rib cage expansion in healthy adults. Methods Thirty healthy adults underwent chest wall vibration under three randomised conditions: 4-point stimulation, 8-point stimulation, and sham control. Vibration was synchronised with resting breathing. Tidal volume (V t ), minute ventilation (V e ), and thoracoabdominal displacement were measured. A linear mixed-effects model was used to compare outcomes across conditions. Results The 8-point stimulation significantly increased V t and V e compared to the 4-point and control conditions ( p < 0.01). Rib cage displacement also increased, while abdominal motion remained unchanged. These findings suggest that enhanced ventilation was primarily due to rib cage expansion. Conclusion Synchronized multi-site intercostal vibration improves ventilation by increasing rib cage expansion in healthy adults and may offer a novel non-invasive respiratory facilitation strategy.