frontiers Frontiers in Physiology Q dW = KV + K'a2 sin? (bt) dt + K"a sin3 (bt) dt (4) where this expression can be thought of as three components, the modeling of the elastic work, viscous work, and the work associated with turbulent resistance, respectively. The integration of the Equation 4, produces the equation of work for a single inspired breath using the airflow velocity data, defined by W = >KV,+ 1K'n2fv? + 2K"2f2vp. (5) This model serves its purpose perfectly when estimating the fo Download breath, that is, a breath that has only one frequency, and only The first term of Equation 5, the elastic force, has no direct contribution from the frequency of the instantaneous flow. However, frequency does significantly