Absent phasing of respiratory and locomotor rhythms in running mice

Examining whether and how the rhythms of limb and breathing movements interact is highly informative about the mechanistic origin of hyperpnoea during running exercise. However, studies have failed to reveal regularities. In particular, whether breathing frequency is inherently proportional to limb velocity and imposed by a synchronization of breaths to strides is still unclear. Here, we examined respiratory changes during running in the resourceful mouse model. We show that, for a wide range of trotting speeds on a treadmill, respiratory rate increases to a fixed and stable value irrespective of trotting velocities. Respiratory rate was yet further increased during escape-like running and most particularly at gallop. However, we found no temporal coordination of breaths to strides at any speed, intensity, or gait. Our work thus highlights that exercise hyperpnoea can operate, at least in mice and in the presently examined running regimes, without phasic constraints from limb movements.

Pulmonary function

Chapter 18 describes important developmental changes in pulmonary structure and function that contribute to changes in the ventilatory response to exercise during growth, describes age and sex differences in the ventilatory response to exercise, provides insights into the developmental aspects of the control of exercise hyperpnoea, explores current issues regarding the ventilatory response to exercise in children, and discusses the potential for training adaptations of pulmonary function during growth.